source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-244 | evolution, taxonomy
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild.
That last part takes care of the ligers and tiglons. But what if we consider plants? Under the definition I just gave, most grasses (around 11,000 species) would have to be considered as one species. In the wild, most grasses will freely pollinate related species and produce hybrid seed, which germinates. You might then think we could just modify the definition to specify that the offspring must be fertile (i.e. able to reproduce with one another)...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild to produce fertile progeny.
Unfortunately, the situation is still more complicated (we've barely started!). Often wild hybridisation events between plants lead to healthy, fertile offspring. In fact common wheat (Triticum aestivum) is a natural hybrid between three related species of grass. The offspring are able to breed freely with one another.
Perhaps we could account for this by taking into account whether the populations usually interbreed, and whether they form distinct populations...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of populations or meta-populations of related individuals that resemble one another, are able to breed among themselves, but do tend not to breed freely with members of another species in the wild to produce fertile progeny.
The following is multiple choice question (with options) to answer.
What is a species that plays an especially important role in it's community called? | [
"Leader",
"Invasive",
"keystone",
"complement"
] | C | Some predator species are known as keystone species. A keystone species is one that plays an especially important role in its community. Major changes in the numbers of a keystone species affect the populations of many other species in the community. For example, some sea star species are keystone species in coral reef communities. The sea stars prey on mussels and sea urchins, which have no other natural predators. If sea stars were removed from a coral reef community, mussel and sea urchin populations would have explosive growth. This, in turn, would drive out most other species. In the end, the coral reef community would be destroyed. |
SciQ | SciQ-245 | population-biology, population-dynamics
Title: Why will world population keep growing if all women have only 2.1 children Why is it that, even if we were going to immediately agree that every women will not have more than 2.1 children on average, the world population would continue to grow for another 60 years? I've learned that a TFR of 2.1 means the population is at 0 growth rate. I guessed the answer was the population-lag effect, but since we are assuming that ALL women immediately have only 2.1 children on average, wouldn't there be a 0 population growth immediately and not after 60 years? Thanks in advance! As you mention, the population-lag effect is responsible for this. From The Wikipedia article on TFR: http://en.wikipedia.org/wiki/Total_fertility_rate#Population-lag_effect
A population that has recently dropped below replacement-level
fertility will continue to grow, because the recent high fertility
produced large numbers of young couples who would now be in their
childbearing years.
Thus, even if the current TFR implies long-term stability, the recent history of TFR values will continue to affect birth rates, and thus population growth/decrease, in the future.
Imagine that you have a stable population, with static birth and death rates. Now imagine that the birth rate during a single year for some reason doubles before dropping back to normal the next year, thus transiently increasing TFR. Now, it is easy to see that when the newly born, larger-than-normal generation reaches reproductive age, the population will increase again because the birth rate will increase in proportion with the size of the generation, while the death rate is unaffected until the enlarged generation reaches old age and starts dying off. Later, the population will decrease to its long-term stable level, which will be larger than before the TFR spike.
The following is multiple choice question (with options) to answer.
What term that shows how fast a population is growing includes new members added to the population over a given period, as well as old members removed from the population? | [
"birth rate",
"population density",
"emigration",
"growth rate"
] | D | The population growth rate is how fast a population is growing. The letter r stands for the growth rate. The growth rate equals the number of new members added to the population in a year for each 100 members already in the population. The growth rate includes new members added to the population and old members removed from the population. Births add new members to the population. Deaths remove members from the population. The formula for population growth rate is:. |
SciQ | SciQ-246 | amateur-observing, saturn, planetary-ring
Title: Are the radial spokes in Saturn's rings reliably visible via ground-based telescopes In the mid 1970's, Franklin and O'Meara saw persistent "radial spoke-like features" in the rings of Saturn, that should not have existed due to the differential rotation of the rings. A publication on this observation was rejected by a journal apparently on the grounds that the phenomenon was considered to be illusory (c.f Sciparelli/Lowell's Martian canals?).
From "Seeing in the Dark: How
Amateur Astronomers Are Discovering the Wonder" By Timothy Ferris.
My question is, how reliably were these features visible from the ground-based telescopes of the day? Could sufficiently strong evidence for the existence been obtained before images from space probes? Was the rejection of the paper reasonable in the historical context in which the paper was submitted? Bryan (2007) gives a number of reasons why O'Meara's discovery was largely discounted:
As you stated, the behavior was entirely inconsistent with Keplerian predictions of motion.
While O'Meara was able to reproduce his findings, no other independent observers could.
The detections were done entirely visually, rather than with numerical measurements.
There had been previous observations (i.e. in the 19th century), but in different places in the rings (the A and C rings, not the B ring). These have never been confirmed, and it is still believed that these were actually illusions.
Reliable observations from ground-based telescopes, especially those of amateurs, have arisen within the past decade or so. Since 2007, 67 "candidate" observations have been made of the spokes, many during the 2009 Saturnian equinox (keep in mind that the spokes may be a seasonal phenomenon). One additional factor that made observations difficult was that the spokes seemed to have vanished, even from space probes, in the years after the Voyager observations, making it impossible for ground-based telescopes to see them.
The following is multiple choice question (with options) to answer.
The rings of what planet can be easily seen from earth? | [
"jupiter",
"Neptune",
"Venus",
"saturn"
] | D | All of the outer planets have numerous moons. They also have planetary rings made of dust and other small particles. Only the rings of Saturn can be easily seen from Earth. |
SciQ | SciQ-247 | solar-system, jupiter, gas-giants, saturn, uranus
From the second hit:
Jupiter is a giant gas planet with an outer atmosphere that is mostly
hydrogen and helium with small amounts of water droplets, ice
crystals, ammonia crystals, and other elements. Clouds of these
elements create shades of white, orange, brown and red. Saturn is also
a giant gas planet with an outer atmosphere that is mostly hydrogen
and helium. Its atmosphere has traces of ammonia, phosphine, water
vapor, and hydrocarbons giving it a yellowish-brown color. Uranus is a
gas planet which has a lot of methane gas mixed in with its mainly
hydrogen and helium atmosphere. This methane gas gives Uranus a
greenish blue color Neptune also has some methane gas in its mainly
hydrogen and helium atmosphere, giving it a bluish color
The following is multiple choice question (with options) to answer.
What planet is a blue green color? | [
"sirius",
"uranus",
"Mercury",
"Mars"
] | B | Uranus is a lot like Jupiter and Saturn. The planet is composed mainly of hydrogen and helium. There is a thick layer of gas on the outside. Further on the inside is liquid. But Uranus has a higher percentage of icy materials than Jupiter and Saturn. These materials include water, ammonia, and methane. Uranus is also different because of its blue-green color. Clouds of methane filter out red light. This leaves a blue-green color. The atmosphere of Uranus has bands of clouds. These clouds are hard to see in normal light. The result is that the planet looks like a plain blue ball. |
SciQ | SciQ-248 | organic-chemistry, inorganic-chemistry
But then, some inorganic compounds do have carbon too, and there may even be some compounds that some call organic, and others call inorganic, like $CO_2$.
As I have felt it, in my learnings so far, it's like inorganic chemistry is the default chemistry and organic chemistry goes a step beyond.
But I don't quite grasp the difference.
What is the real semantics behind the word "organic"?
For example, we humans are made of loads of water, and that's a pretty organic thing to me. But then, water is inorganic.
Diamonds are the carbon top of the cake, and do not transmit the idea of being an "organic" thing.
Another very confusing thing are polymers, chanins of loads of carbons with other elements, in many shapes and textures. To me, a piece of "plastic" is not a very organic thing, but indeed, they are!
That brings the semantics into an even more confusing level.
And of course, there must be historical reasons for those chosen words.
Could someone please point out where this distinction comes from and why it is important?
With all my respect to science and the people who made chemistry a useful thing. This question is not about critics, it's about not knowing the facts, so of course I am the ignorant here.
Related and useful: What is the definition of organic compounds? IUPAC is the International Union of Pure and Applied Chemistry, they make recommendations on the nomenclature. IUPAC mentions that the difference between organic and inorganic is not distinct. To quote "The boundaries between ‘organic’ and ‘inorganic’ compounds are blurred." in Brief Guide to the Nomenclature of Inorganic Chemistry R. M. Hartshorn, K.-H. Hellwich, A. Yerin.
Since the terminology of organic vs. inorganic is all human classification, it is not a binary system 0 or 1. What we can say now is that traditionally, all organic compounds do contain carbon. It can come from natural sources or purely synthetic. There is no such restriction. Plastic is an organic compound because it contains a lot of carbon chains.
Note that this word organic, as used in chemistry, has nothing to with the buzz word used in marketing of organic food, organic fruits, organically grown stuff. The word organic comes from French organique designating the jugular vein, hence related to organs or living beings.
The following is multiple choice question (with options) to answer.
The simplest class of organic compounds is the what? | [
"gas",
"particles",
"hydrocarbons",
"Phenols"
] | C | isolating the individual components, preservationists are better able to determine the condition of an object and those books and documents most in need of immediate protection. The simplest class of organic compounds is the hydrocarbons, which consist entirely of carbon and hydrogen. Petroleum and natural gas are complex, naturally occurring mixtures of many different hydrocarbons that furnish raw materials for the chemical industry. The four major classes of hydrocarbons are the alkanes, which contain only carbon–hydrogen and carbon–carbon single bonds; the alkenes, which contain at least one carbon–carbon double bond; the alkynes, which contain at least one carbon–carbon triple bond; and the aromatic hydrocarbons, which usually contain rings of six carbon atoms that can be drawn with alternating single and double bonds. Alkanes are also called saturated hydrocarbons, whereas hydrocarbons that contain multiple bonds (alkenes, alkynes, and aromatics) are unsaturated. |
SciQ | SciQ-249 | planetary-science, exoplanet
Since the planet hosted the first Foundation it is clearly habitable (i.e. atmosphere, no extreme temperatures). However, I am wondering how could it have so little metals if it seems so similar to Earth (habitability-wise) which has lots of metals. Is this possible in our Universe?
I am interested in answers that use current discovered exoplanets information or some articles that deal with planets come to be.
Question: Is it plausible for a planet that is positioned in the habitable area of a solar system to have little extractable metals? I'm going to approach this question in two steps: what metals are you talking about, and could you have a planet where those metals are not easily extractable.
What metals?
I get the sense that you're specifically referring to the non-lithophile metals, which include the d-block transition metals iron, nickel, copper and gold, and the chalcophile metals zinc, tin, lead, arsenic, mercury and silver.
This is an important distinction, since the advent of metallurgy was a critical step in human development in taking us out of the Stone Age, and it might be reasonable to posit that any advanced civilisation would follow a similar trajectory.
The final phase of the Stone Age, as we transitioned from the Neolithic to the Bronze Age, is called the Chalcolithic because it's marked by the first use of copper (although lead-smelting may have slightly preceded copper-working in some places). The Bronze Age initially alloyed copper with arsenic, but bronze made from copper and tin turned out to be both less toxic and more durable; bronze, in turn, was replaced by superior steel tools. Steel requires a sophisticated ferrous metallurgy involving iron alloys with a carbon content, and knowing how to make it is the mark of a culture's entry into the Iron Age.
[NB: There are plenty of iron relics that predate the Iron Age, but these were made from meteoric iron, an iron-nickel alloy that requires no prior smelting of ores; terrestrial iron's high melting point is well beyond the temperatures that could be achieved in Stone Age pottery kilns.]
Easily extractable?
Wikipedia describes the early stage of the Earth's formation:
The following is multiple choice question (with options) to answer.
Some meteorites are made of iron and nickel and are thought to be very similar to what part of the earth? | [
"mantel",
"core",
"crust",
"shelf"
] | B | Scientists study meteorites to learn about Earth’s interior. Meteorites formed in the early solar system. These objects represent early solar system materials. Some meteorites are made of iron and nickel. They are thought to be very similar to Earth's core ( Figure below ). An iron meteorite is the closest thing to a sample of the core that scientists can hold in their hands!. |
SciQ | SciQ-250 | human-biology, senses
Olfaction (smell, as carried out by neurons in the nasal epithelium; e.g. smell of vanilla, and smell of bad food)
Gustation (taste, as carried out by neurons on the tongue; e.g. salt, sugar)
Antigen chemosensing (chemical sensing, as carried out by, for instance, immune antigen receptors on B cells)
Hormonal signaling chemosensing (chemical sensing of hormones such as insulin, as carried out for instance by myocytes)
Starch sensing? (amylase in saliva can be used as a test for digestable starch)
Visual system, at the retina?
Visible light (sensing electromagnetic radiation on the order of a few hundred nanometers in wavelength)
Internal methanol sensing (the visual system as a sensor for methanol, which disproportionately affects myelin surrounding the optic nerve)
Pressure sensing (see phosphenes)
The vestibular system
Gravity sensing
Balance
Coordination
Motion sensor
Head position sensor
Spatial orientation
Skin
thermosensation (touching a hot kettle!)
Nociception (pain sensing)
allergen sensing
sensor for gamma rays, X-rays and UV light (indicated by radiation burns, development of skin cancer, sunburns, etc.)
Bones and muscles?
Kinesthetic and bodily proprioception
Brain/mind/mental/social senses?
mental pain
boredom
mental or spiritual distress
sense of self and other, including friendship, power, place in social hierarchy, reputation, companionship
motivation and love (oxytocin, dopamine, etc. in limbic systems and other neural correlates)
I'm sure some would agree, and some would disagree about the specific cases I provide. Thus the definition of senses, or sensing, seems to be opinion-based or at the very least very sensitive to an agreed-upon operational definition, for which there is none.
The following is multiple choice question (with options) to answer.
Which pathway carries somatosensory information from the face, head, mouth, and nasal cavity? | [
"cranial pathway",
"posterior pathway",
"dual pathway",
"trigeminal pathway"
] | D | The trigeminal pathway carries somatosensory information from the face, head, mouth, and nasal cavity. As with the previously discussed nerve tracts, the sensory pathways of the trigeminal pathway each involve three successive neurons. First, axons from the trigeminal ganglion enter the brain stem at the level of the pons. These axons project to one of three locations. The spinal trigeminal nucleus of the medulla receives information similar to that carried by spinothalamic tract, such as pain and temperature sensations. Other axons go to either the chief sensory nucleus in the pons or the mesencephalic nuclei in the midbrain. These nuclei receive information like that carried by the dorsal column system, such as touch, pressure, vibration, and proprioception. Axons from the second neuron decussate and ascend to the thalamus along the trigeminothalamic tract. In the thalamus, each axon synapses with the third neuron in its respective pathway. Axons from the third neuron then project from the thalamus to the primary somatosensory cortex of the cerebrum. The sensory pathway for gustation travels along the facial and glossopharyngeal cranial nerves, which synapse with neurons of the solitary nucleus in the brain stem. Axons from the solitary nucleus then project to the ventral posterior nucleus of the thalamus. Finally, axons from the ventral posterior nucleus project to the gustatory cortex of the cerebral cortex, where taste is processed and consciously perceived. The sensory pathway for audition travels along the vestibulocochlear nerve, which synapses with neurons in the cochlear nuclei of the superior medulla. Within the brain stem, input from either ear is combined to extract location information from the auditory stimuli. Whereas the initial auditory stimuli received at the cochlea strictly represent the frequency—or pitch—of the stimuli, the locations of sounds can be determined by comparing information arriving at both ears. |
SciQ | SciQ-251 | the light but not on the intensity. For more such videos please go to http://vidhyasangam.com/Videos.html Height, mass and gravitational strength. This question is off-topic. The kinetic energy is then 1 2 m i v i 2, and summation gives the total kinetic energy of the body: E kin = 1 2 m 1 v 1 2 + 1 2 m 1 v 2 2 + ⋯ = 1 2 Ω 2 ( m 1 r 1 2 + m 2 r 2 2 + ⋯ ) . Friction and movement. D. mass and velocity. Using the kinetic energy equation. Kinetic energy depends on the mass and velocity of the body in motion, with the velocity contributing more to the overall kinetic energy of the body. If you count the reduction in kinetic energy of the train together with the increase in kinetic energy of the ball, the sum is the same regardless of what reference frame you choose. Our mission is to provide a free, world-class education to anyone, anywhere. 5,000 J. solve : … Kinetic energy is one of several types of energy that an object can possess. Using the kinetic energy equation. K.E is directly proportional to temp. C. Height. Does the kinetic energy change depending on the direction of the velocity? Only velocity. B. c. D. Tags: Question 12 . $\begingroup$ @user248881 In the standard model of particle physics all photons are point particles, i,e, have no size. It is given as K E = a s 2, where a is a constant. kinetic energy synonyms, kinetic energy pronunciation, kinetic energy translation, English dictionary definition of kinetic energy. The kinetic energy of a moving object can be calculated using the equation: Kinetic energy = $$\frac{1}{2}$$ x mass x (speed) 2. 2 See answers Nonportrit Nonportrit The amount of kinetic energy an object has depends on its "speed." Only mass. You are very important to us. Linear Kinetic energy of a object is dependent upon the linear speed of an object and its mass( we can use the scalar term “speed” as energy is a scalar quantity and is independent of the direction of motion of body). Kinetic energy depends on A. only mass. When the particles are moving very fast, we feel the substance and say "That's hot!". The equation
The following is multiple choice question (with options) to answer.
The amount of kinetic energy in a moving object depends directly on its mass and what else? | [
"volume",
"density",
"velocity",
"direction"
] | C | The amount of kinetic energy in a moving object depends directly on its mass and velocity. An object with greater mass or greater velocity has more kinetic energy. You can calculate the kinetic energy of a moving object with this equation:. |
SciQ | SciQ-252 | brain, exercise
Neuromodulators are involved in a variety of processes including pain
modulation, reward, response to stress, and autonomic control.
In humans, acute exercise causes significant increases in peripheral
levels of endogenous opioids; this effect is intensity-dependent,
corresponds to acute exercise-induced changes in HPA axis hormones,
and is linked to improvements in mood.
Though the endogenous opioids have received much attention in terms of
their involvement in the “runner’s high”, scientists are beginning to
understand that endocannabinoids may be equally or perhaps more
involved.
Other sources:
Effects of physical exercise on anxiety, depression...(Clinical Psychology Review, 2001):
Acutely, emotional effects of exercise remain confusing, both positive
and negative effects being reported.
...or as Alex Corb, PhD says in Boosting Your Serotonin Activity (Psychology Today):
Interestingly, if you try to do too much exercise, or feel forced into
doing it, it may not have the right effect. Recognizing that you are
choosing to exercise changes its neurochemical effect. That may be a
result of your ancient instincts — the difference between running
because you're hunting something, and running because it's hunting
you.
How to increase serotonin in the human brain without drugs (Journal of Psychiatry & Neuroscience, 2007):
Exercise improves mood in subclinical populations as well as in
patients. The most consistent effect is seen when regular exercisers
undertake aerobic exercise at a level with which they are familiar.
The following is multiple choice question (with options) to answer.
Cycling, shoveling snow and cross-country skiing are examples of what kind of heart-strengthening activity? | [
"aerobic",
"anaerobic",
"exercise",
"metabolism"
] | A | When done regularly, aerobic activities, such as cycling, make the heart stronger. Other aerobic activities include mowing lawn, shoveling snow and cross country skiing. |
SciQ | SciQ-253 | materials, pressure, strength
It seems likely that I'll be needing the compressive strength here, because the theoretical dome is being put at the bottom of the theoretical sea. It's going to be compressed. But these numbers have very little context (at least for me, I don't have an engineering degree). I mainly worry about thickness. In my mind, when a wall is thicker, it means it can hold more weight, can withstand heavier punches and generally breaks less easily. I don't see this reflected in this number. It also doesn't take the shape of the object in mind. A sphere is supposedly stronger then any other shape (I found this cool site selling dome bunkers). But this too doesn't seem reflected in the compressive strength value.
It might also have to do with the size effect, but that seems to weaken - not strengthen - structures and would only be applicable if I made the outer diameter variable.
If anyone can help me any further it would be very much appreciated. I really want to make clear that I'm not asking you to do my homework (this isn't really homework, but still). Pointing me vaguely in the right direction is also extremely helpful. Thanks in advance! A shell structure under external pressure is likely to fail in buckling before it reaches the compressive strength of the material.
Buckling of curved shells is a complex problem in general, but for a complete sphere a simple formula (source here) is $$P = \frac{2E}{\sqrt{3(1-\nu^2)}}\frac{t^2}{r^2}$$
Where $E$ and $\nu$ are Young's modulus and Poisson's ratio, $t$ is the shell thickness and $r$ is the mean radius.
Taking $E$ = 510,000 psi and $\nu$ = 0.33 (sources, here and here) This gives about $31,000$ psi for your dimensions.
These buckling formulas are very imprecise and I would take a safety factor of at least 10 times, which would give a safe buckling load of about 3000 psi.
The following is multiple choice question (with options) to answer.
What take the shape of their container, and are relatively easy to compress? | [
"fluids",
"gases",
"molecules",
"semi-fluids"
] | B | The story is quite different for gases. Gases take the shape of their container, and they are relatively easy to compress. There are fewer gas particles per unit volume than for the same substance in the liquid or solid form. In fact, the liquid form of a given material is generally several hundred times more dense than the gas form at normal pressures. Despite the large amounts of empty space, a sample of a gas contains many particles moving around, colliding and imparting force on their surroundings. For example, in a one mole sample of gas at 0°C and 1 atm of pressure, each cubic centimeter contains roughly 2.7 × 10 19 molecules. Each molecule participates in several billion collisions every second, moving only about 10-100 nanometers between collisions. Additionally, these gas particles move at very high speeds. For example, at 25°C, the average speed of hydrogen molecules in a sample of hydrogen gas is 1960 m/s. |
SciQ | SciQ-254 | optics, air
Title: What's the name for taking pictures of air flow in a normal room? There is a way to photograph air in a room. It makes convection, breathing and movement visible. The result looks a bit like a soap bubble.
This is some kind of optical effect. No special gases or fogs or powders are used.
What's this special form of photography called? You think of Schlieren method?
Google for Schlieren or Schlieren-photography.
[EDIT]: Wikipedia article Schlieren photography
The following is multiple choice question (with options) to answer.
What is moving air called? | [
"wind",
"clouds",
"steam",
"humidity"
] | A | Moving air, like moving water, causes erosion. Moving air is called wind. |
SciQ | SciQ-255 | virology
lentiviral vectors packaging RNA much smaller than 10,000 nucleotides have been shown to efficiently transduce cells and are thus capable of genome uncoating and integration.
OP seems to be familiar with the details of the subject, so I recommend reading the review in full if you have access.
The following is multiple choice question (with options) to answer.
What property makes bone marrow cells ideal for gene therapy? | [
"lifelong reproduction",
"irreversible reproduction",
"behavior reproduction",
"Matching"
] | A | |
SciQ | SciQ-256 | inorganic-chemistry, ions, identification
Title: Identifying a quadruply charged anion containing three carbon atoms
This linear polyatomic ion containing three atoms of carbon has a negative four charge and is only found bonded with lithium and magnesium.
Could anyone identify this for me? It's from a quiz bowl clue that doesn't have the answer with it.
Sesquicarbide
A quick Google search suggests that $\ce{Li4C3}$ is a real compound, but based on what I saw in the links, it probably is not ionic in the same way that lithium acetylide $\ce{Li2C2}$ is.
$\ce{Mg2C3}$ appears to be the formula for magnesium carbide, or at least a magnesium carbide.
A carbide is a binary compound of carbon and a less electronegative element, usually a metal or metalloid. Carbide is also a generic name for mono- and polyatomic anions containing only carbon. The following ions would all carbide ions: $\ce{C^{4-}, C2^2-, C2^{4-}, C2^{6-}, C3^{4-}, C3^{6-1}, C3^{8-}}$, etc.
The special name of three of these carbide ions are:
$\ce{C^{4-}}$ - Methide
$\ce{C2^{2-}}$ - Acetylide
$\ce{C3^{4-}}$ - Sesquicarbide
The following is multiple choice question (with options) to answer.
What is the name of the two metalloids in the carbon group called? | [
"silicon and germanium",
"silicon and gold",
"titantium and copper",
"silver and gold"
] | A | Group 14 is called the carbon group. This group contains two metalloids: silicon and germanium. Carbon is a nonmetal, and the remaining elements in this group are metals. |
SciQ | SciQ-257 | oceanography, stratigraphy, paleogeography
Title: Was the Caribbean Sea a closed sea during the last glaciation? Taking a look at Google Earth the straits between the Caribbean Sea and the Atlantic Ocean are not very deep.
The sealevel during the last glaciation was 120 meters lower than the present level.
Was the Caribbean Sea a closed or semi-closed sea during the last glaciation or the straits were deep enough to make it a connected sea? Thanks to @Eartworm I learned today I was totally incorrect: the straits are more than 2000 meters deep.
Tool to see bathymetry, navionics.com
The following is multiple choice question (with options) to answer.
What is the name of the zone where water is deeper than 200 meters called? | [
"eccentric zone",
"aphotic zone",
"euphotic zone",
"transition zone"
] | B | The aphotic zone is water deeper than 200 meters. This is where too little sunlight penetrates for photosynthesis to occur. As a result, producers must make "food" by chemosynthesis , or the food must drift down from the water above. |
SciQ | SciQ-258 | dna, radiation
Title: How do electrons destroy DNA bonds in radiation? Malignant tumors can be treated by radiation therapy. Most commonly it's radiotherapy with photons, or protons and so on. The common denominator for both types is that the radiation creates electrons inside the body via different effects.
What I haven't quite understood is how these electrons destroy the DNA bonds in the tumor and how this aids in killing off the cancer cells? Is it due to the generation of heat, or otherwise? I think you have a fundamental misunderstanding of the chemical reactions involved in radiation therapy. Neither photon based or proton based therapies "create electrons", but they do cause ionization by adding enough energy to existing electrons around atoms so that the electron is ejected from the atom, creating an ion or free radical, which can then undergo chemical reaction.
Photons, typically gamma rays, X-rays, and high energy UV, typically interact with water molecules and produce free radicals, including the dangerous hydroxyl radical. The hydroxyl radical can interact with proteins and DNA and damage those molecules, but has a very short half-life. Molecular oxygen can help increase the damage by reacting with the hydroxyl radical to produce Reactive Oxygen Species, ROS, which can also damage DNA or protein. However, many tumors have low oxygen concentration that reduces the effectiveness of photon based radiation therapy.
To overcome this, many patients receive proton based radiation therapy. Protons are much heavier than photons (I guess infinitely heavier than a photon, since photons have no mass) and therefore scatter to a much smaller extent. They just sort of plow through tissue and knock electrons out of orbitals as they collide with molecules such as DNA or protein. They don't rely so much on free radical generation or ROS, so low oxygen levels don't reduce their effectiveness.
The goal is damage the DNA to induce double strand breaks which are hard to repair in fast growing cancer cells. Because they grow so quickly, they are already stressed and their DNA repair machinery is less effective than in healthy cells. If their DNA can be sufficiently damaged, the cell will die.
For more information about these processes, please see these wikipedia articles on Radiation Therapy, Radiolysis, Linear Energy Transfer, and Free Radical Damage to DNA.
The following is multiple choice question (with options) to answer.
Diagnosing and treating cancer is a beneficial use of what potentially dangerous energy? | [
"radiation",
"mechanical",
"solar",
"thermal"
] | A | Radiation has several important uses, including diagnosing and treating cancer. |
SciQ | SciQ-259 | biochemistry, enzymes, nutrition, human-physiology, digestion
Title: Secondary/ Acquired lactose intolerance
Acquired lactose intolerance may occur due to a sudden and high intake of milk-based diets. Lactase is an inducible enzyme.
So if lactase is an inducible enzyme then why increase intake of lactose is causing negative effect? Why more lactase isn't produced in more lactose intake conditions? Searching for the quote you included led me to the original source.
I wouldn't spend too much time worrying about this particular source, and look at some other sources for more information on acquired lactose intolerance. I think there may be some translation/language issues with this section in this particular source. I believe what the author is trying to convey is not that the intolerance is coming from the increased intake, but that the symptoms of intolerance are coming from a sudden increase in lactose intake following a period of low/no lactose intake, where "sudden" essentially means "faster than lactase induction can occur."
That said, I think this is really more an issue of poor wording in a textbook. The whole section is a bit strangely worded, particularly the part on "flatulence" which this author describes as "characterized by increased intestinal motility, cramps, and irritation" - while these issues may certainly accompany flatulence, this definition of these symptoms characterizing flatulence is not correct, as one can certainly have flatulence with normal intestinal function.
The following is multiple choice question (with options) to answer.
Many adults and some children suffer from a deficiency of lactase. these individuals are said to be lactose intolerant because they cannot digest the lactose found in what? | [
"fruit",
"milk",
"peanuts",
"meat"
] | B | Many adults and some children suffer from a deficiency of lactase. These individuals are said to be lactose intolerant because they cannot digest the lactose found in milk. A more serious problem is the genetic disease galactosemia, which results from the absence of an enzyme needed to convert galactose to glucose. Certain bacteria can metabolize lactose, forming lactic acid as one of the products. This reaction is responsible for the “souring” of milk. |
SciQ | SciQ-260 | electricity, electric-circuits, voltage, electrical-engineering
UPDATE:
To show what can happen if the neutral (grounded circuit conductor) is used to provide a safety ground for an appliance on a branch circuit instead of the equipment grounding conductor (the proper safety ground) refer to the figures below;
Figure 1 shows three appliances on a branch circuit. The metal housings of each appliance is connected to the equipment grounding conductor (safety ground), or the third wire, of the branch circuit serving the appliances. In the event of a fault between the hot (live) conductor and the housing, the fault current is carried to ground on the equipment grounding conductor limiting the voltage the person might experience if simultaneously touching the housing and some other grounded part (the earth, another grounded appliance, etc..). Note that if there is an open circuit somewhere in the equipment grounding conductor between the last appliance and the service panel, all that happens is a loss of a safety ground in the event of the fault shown. The open circuit does not in and of itself cause a hazardous condition.
In Figure 2 the third appliance is grounded by means of the grounded circuit conductor (neutral conductor). Note that if an open circuit occurs in the branch circuit neutral conductor (as shown in the connections to the second appliance) the load current in the third appliance cannot return to the service panel through the neutral conductor. It has to return through the person's body. The only impedance limiting that current is the load impedance of the third appliance, which may be several amperes. Since for 60 hz sinusoidal current it only takes between 20 mA and 100 mA of current through the body to possibly cause a lethal electric shock and since the body impedance can be as low as 500 Ohms, a lethal electric shock is possible.
Hope this helps.
The following is multiple choice question (with options) to answer.
Three-prong plugs, circuit breakers, and gfci outlets are safety features that recognize the danger of what? | [
"electricity",
"magnetism",
"gravity",
"heat"
] | A | Because electricity can be so dangerous, safety features are built into modern electric circuits and devices. They include three-prong plugs, circuit breakers, and GFCI outlets. You can read about these three safety features in the Figure below . You can learn more about electric safety features in the home by watching the video at this URL: http://www. dailymotion. com/video/x6fg5i_basics-of-your-home-s-electrical-sy_school . |
SciQ | SciQ-261 | biochemistry
Title: Is hydrolysis of polypeptides and polysaccharides "anabolic" or "catabolic" When a polysaccharide or polypeptide is hydrolyzed into mono-saccharides or amino acids, the building blocks can be oxidized to release energy. The oxidation is considered to be catabolic since it reduces the building blocks to simple compounds: carbon dioxide, water, ammonia, and releases energy.
Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
Is it proper to call the isolated process of "hydrolysis" of proteins and polysaccharides "catabolic"?
Are protein synthesis, glycogen synthesis, (and triglyceride formation), by dehydration synthesis processes that require energy or release energy. I think that they release energy which is semantically interesting since protein and glycogen synthesis are the main examples of anabolism in the body but may actually release energy which is a key component of the definition of catabolism. Even if the energy released from protein synthesis is not generating ATP directly, wouldn't the heat produced conserve ATP in the long run.
1) Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Under physiological conditions, it is a process that goes forward, i.e. the Gibbs energy is negative. As a consequence, it can happen outside of cells in the absence of ATP. When we eat, the hydrolysis of polysaccharides starts in our mouths, while the hydrolysis of proteins occurs under harsher (acidic) conditions in the stomach and continues in the intestine (slightly basic conditions).
For warmblooded animals like us, exothermic or endothermic is less important, but you could look it up.
2) Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
The following is multiple choice question (with options) to answer.
Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in what? | [
"crystals bonds",
"chemical bonds",
"molecular bonds",
"liquid bonds"
] | B | Catabolic Reactions Catabolic reactions break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds. These energy releases (conversions) are not 100 percent efficient. The amount of energy released is less than the total amount contained in the molecule. Approximately 40 percent of energy yielded from catabolic reactions is directly transferred to the high-energy molecule adenosine triphosphate (ATP). ATP, the energy currency of cells, can be used immediately to power molecular machines that support cell, tissue, and organ function. This includes building new tissue and repairing damaged tissue. ATP can also be stored to fulfill future energy demands. The remaining 60 percent of the energy released from catabolic reactions is given off as heat, which tissues and body fluids absorb. Structurally, ATP molecules consist of an adenine, a ribose, and three phosphate groups (Figure 24.2). The chemical bond between the second and third phosphate groups, termed a high-energy bond, represents the greatest source of energy in a cell. It is the first bond that catabolic enzymes break when cells require energy to do work. The products of this reaction are a molecule of adenosine diphosphate (ADP) and a lone phosphate group (Pi). ATP, ADP, and Pi are constantly being cycled through reactions that build ATP and store energy, and reactions that break down ATP and release energy. |
SciQ | SciQ-262 | organic-chemistry, spectroscopy, analytical-chemistry, nmr-spectroscopy
Obviously there is some guess work in here and if it was an important project I'd do some further experiments and look for some additional model compounds in order to confirm these assignments and remove the discrepancies, but this is a good start.
The following is multiple choice question (with options) to answer.
In qualitative analysis, reagents are added to an unknown chemical mixture in order to induce what? | [
"motion",
"precipitation",
"erosion",
"sunlight"
] | B | Selective precipitation can also be used in qualitative analysis. In this method, reagents are added to an unknown chemical mixture in order to induce precipitation. Certain reagents cause specific ions to precipitate out; therefore, the addition of the reagent can be used to determine whether the ion is present in the solution. |
SciQ | SciQ-263 | climate-change, climate, paleoclimatology, carbon-cycle
Title: Did climate cool down when underground hydrocarbons stocks formed? As far as I understand, the dominant theory of modern climate change says that recent warming is mainly caused by the massive burning of hydrocarbons that used to be stored in solid form mostly underground as petroleum, coal, etc.
This suggests that the reverse process should contribute to a cooling of the climate (or to a slowed down warming if other processes are at play at the same time).
In particular, a cooling should have occurred throughout the period when the stocks of underground hydrocarbons were formed by the "pilling" of organic remains.
My questions:
The following is multiple choice question (with options) to answer.
While climate change in earth history was due to natural processes, what is primarily to blame for recent global warming? | [
"volcanos",
"factories",
"wars",
"human actions"
] | D | Climate change in Earth history was due to natural processes. Recent global warming is due mainly to human actions. The burning of fossil fuels releases greenhouse gases into the air. This creates greater greenhouse effect and global warming. |
SciQ | SciQ-264 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
What is the simplest life cycle? | [
"metamorphic cycle",
"diploid life cycle",
"binary life cycle",
"haploid life cycle"
] | D | The haploid life cycle ( Figure below ) is the simplest life cycle. It is found in many single-celled organisms. Organisms with a haploid life cycle spend the majority of their lives as haploid gametes. When the haploid gametes fuse, they form a diploid zygote. It quickly undergoes meiosis to produce more haploid gametes that repeat the life cycle. |
SciQ | SciQ-265 | astronomy, moon, earth
[EDIT: To answer more of your questions, there are lots of stable orbits, and the Moon can also act to stabilize, not just destabilize orbits- see http://en.wikipedia.org/wiki/Trojan_(astronomy) . Any stable orbit would have to be above the top of the atmosphere, about 100 km, or else friction with atmospheric gas would drag it down to Earth. Moons could range from specks of dust up to potentially extremely large, even as large as the first Moon, but at great size the options for stability become much more limited. See http://en.wikipedia.org/wiki/Euler%27s_three-body_problem. All of this arises from classical, Newtonian mechanics. To greatly simplify history, Tycho Brahe took a lot of data on planet positions in the sky, Kepler took those observations and developed his purely empirical laws of orbital motion, and Newton took those empirical laws and developed a theoretical framework to account for them.]
Further reading-
http://en.wikipedia.org/wiki/Orbital_resonance
http://en.wikipedia.org/wiki/Rings_of_Saturn
*Some gaps are due to other or unknown factors, but for the most part...
The following is multiple choice question (with options) to answer.
What keeps the moon orbiting earth? | [
"Coriolis effect",
"gravity",
"the Sun",
"axial tilt"
] | B | Gravity keeps the Moon orbiting Earth. Gravity keeps the planets orbiting the Sun. |
SciQ | SciQ-266 | electromagnetism, charge
You may ask why it is then so contrary to speak that two opposite charges cancel each other. No objection. All I want you to remember is that it is the net charge that is zero. Individually the charges are not zero. Take the example of an ionic crystal, say $NaCl$, where $Na^+$ and Cl^-$ ions are tightly held together by electrostatic attraction. Both ions have equal and opposite charges. If the interaction between the two lead to the individual destruction of charges (losing property as a charge), then how the solid continues to be so brittle. There is always interaction between the two ions. This means the interaction between the two charges do not cause the charges to lose their charge. It's the effective charge that is zero. We then speak about a system, not about individual charges.
The following is multiple choice question (with options) to answer.
What are formed by the attraction between oppositely charged ions? | [
"inept bonds",
"magnetic bonds",
"ionic bonds",
"soluble bonds"
] | C | Ionic bonds are formed by the attraction between oppositely charged ions. |
SciQ | SciQ-267 | endocrinology
Excitement or stress response, including fast heart rate and breathing and anxiety: short term response: adrenaline; long-term response: cortisol
Appetite: ghrelin, leptin, adiponectin, cholecystokinin, insulin, glucagon-like peptide, gastrointestinal peptide...
Sexual drive: sex hormones, mainly testosterone and estradiol
Sleepiness: melatonin, cortisol
Depression: cortisol, sex hormones (mainly in women)
The point of this answer is to show that some of your feelings can be simply affected by hormones, which are note some ultimate forces, and that being aware of that can help you to control them to some extent.
The following is multiple choice question (with options) to answer.
What produces hormones that directly regulate body processes? | [
"hippocampus",
"lymph glands",
"hypothalamus",
"pancreas"
] | C | The hypothalamus also produces hormones that directly regulate body processes. For example, it produces antidiuretic hormone. This hormone travels to the kidneys and stimulates them to conserve water by producing more concentrated urine. |
SciQ | SciQ-268 | evolution, bioinformatics, sequence-analysis, methods, systems-biology
Title: Is there a system biology approach to compare pathways or famillies of proteins from an evolutionary point of view for the same organism? I would be interested to know if there is a method/analysis or a set of methods to compare two groups of pathways or families of proteins.
I would specifically be interested by a system biology approach which takes all the components of the pathway or family of proteins. I would like to know if there is a method which can not only compare the similarity, homology, divergence and convergence of a family of proteins (like ribosomal proteins) between species but also between groups in the same organism.
For example I would like to compare the molecular components of vesicular trafficking pathways to the molecular components of non-vesicular pathway in the same organism saccharomyces cerevisiae (yeast).
I would greatly appreciate your suggestions. I am not sure that I completely understand, it would be a little easier if you described the problem you are trying to solve or what the motivation is.
However, I think that some of what you want to do can be accomplished by inferring gene/protein trees for each gene/protein of interest across different species (including paralogs, maybe?). This will allow you to see discordance or correlation of evolutionary rates of different genes/proteins across species.
THis kind of analysis is built into HyPhy, though I have never used it. There are also somewhat less involved methods for measuring distances between trees.
You might also be interested in protein co-evolution methods, depending on the question at hand.
Your mentioning systems biology methods suggests that you have something rather different in mind, as none of these things I suggest are really systems biology IMO, but I'm not sure what it would be. Possibly you are interested in integrating e.g. protein-protein interaction or metabolic network information as well, but that would probably involve something more homebrewed that might integrate some of these things.
Hope that helps.
The following is multiple choice question (with options) to answer.
Comparing anatomy, and characterizing the similarities and differences, provides evidence of what process? | [
"emergence",
"devolution",
"regression",
"evolution"
] | D | Take a close look at this gorilla hand. The similarities to a human hand are remarkable. Comparing anatomy, and characterizing the similarities and differences, provides evidence of evolution. |
SciQ | SciQ-269 | oceanography, geochemistry
Title: Why is NaCl so hyper abundant in the ocean? Why is sodium chloride far and away the most abundant salt dissolved in ocean water? Its two constituent ions do have a very high frequency in the crust of the earth, but they are far from the most common. Chlorine is (according to Wikipedia) the 21st most abundant element, and sodium 6th.
I certainly understand that a combination of their solubility and reasonably high frequency would lead one to expect them to be abundant in sea water, but they are hyper abundant, completely dominating all other salt ions. Iron, for example, is twice as abundant, and potassium only a little less abundant, and fluorine more abundant than chlorine.
Moreover, if the salts are deposited in the ocean through weathering of rocks and deposition via rivers, why does the salinity not simply grow and grow? I understand that some is lost due to tectonic activity, but it seems extraordinarily unlikely that these two forces should be equally balanced, and so we would see a significant change in average salinity over time.
(Please note I am migrating this question from the Chemistry SE at their recommendation.) Fluoride salts tend to be not particularly soluble in water. Chloride salts are. The same goes for salts containing sodium versus those containing calcium. Sodium chloride is ridiculously easy to dissolve.
Regarding your second question, it is geological forces that keep salinity more or less constant. People formerly argued that the Earth can't be more than a few hundred million years old because otherwise the river waters running into the oceans would eventually result in an insanely high salinity. It turns out that the Earth's oceans are young (young compared to the 4.5 billion year age of the Earth). The vast majority of oceanic crust is less than 100 million years old. We see huge salt deposits sprinkled across the world because those are the dried up remnants of former seas and oceans. Salt is also drawn into the Earth at subduction zones, where it combines chemically with basalt.
The following is multiple choice question (with options) to answer.
What is the second most abundant element in the earth's crust? | [
"nitrogen",
"silicon",
"carbon",
"helium"
] | B | What is this intricate orb? It is the greatly magnified skeleton of single-celled ocean organisms call radiolarian. The skeleton is made of an element that is extremely common on Earth. In fact, it is the second most abundant element in Earth’s crust. It is also one of the most common elements in the entire universe. What is this important element? Its name is silicon, and it belongs to a class of elements called metalloids. |
SciQ | SciQ-270 | dna, gene-expression
Title: Complexity in creating transgenic animals (e.g., mice) Many papers I have seen describing transgenic rodent models (and presumably applicable to other model organisms) involve the knock-in, or modification to, a single gene, possibly two genes. With respect to recombineering techniques, what prevents targeting multiple genes in a single organism? For instance, if I wanted to simultaneously knock-in some genes and knock-out others within the same mouse, would I be forced to generate individually modified transgenic lines and then do some "fancy" breeding to generate the multiple-modified mice? One reason is the low likelihood of success. Modifying a gene almost always involves a recombination event of plasmid DNA with a target site in the genome (and I say almost just because there may be some method that I don't know about, but all the ones I'm familiar with do). The likelihood of that decreases exponentially with the number of genes you're trying to modify. If you're trying to make several mutants of individual genes the likelihood of success decreases only linearly.
Another reason is having more knowledge and experimental power. You can learn little from a double mutant if you don't also have the individual mutants to compare. In fact, most reviewers would ask for individual mutant data if you've made a double mutant in your paper. This is especially true with flies and worms, as crosses take less time with them.
Also, the more mutant genes you have, the weaker the animal. Your mutants may not be viable at all with too many mutations.
The following is multiple choice question (with options) to answer.
Which kind of genetics approach involves mutating or deleting genes provides researchers with clues about gene function? | [
"impossible genetics",
"reverse genetics",
"inverse genetics",
"possible genetics"
] | B | Watch this short video (http://openstaxcollege. org/l/transgenic) explaining how scientists create a transgenic animal. Although the classic methods of studying the function of genes began with a given phenotype and determined the genetic basis of that phenotype, modern techniques allow researchers to start at the DNA sequence level and ask: "What does this gene or DNA element do?" This technique, called reverse genetics, has resulted in reversing the classical genetic methodology. One example of this method is analogous to damaging a body part to determine its function. An insect that loses a wing cannot fly, which means that the wing’s function is flight. The classic genetic method compares insects that cannot fly with insects that can fly, and observes that the non-flying insects have lost wings. Similarly in a reverse genetics approach, mutating or deleting genes provides researchers with clues about gene function. Alternately, reverse genetics can be used to cause a gene to overexpress itself to determine what phenotypic effects may occur. |
SciQ | SciQ-271 | microbiology, population-biology
Title: How many eukaryotes are there on Earth? I have been reading:
William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF]
wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.
I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above? Could not fit in a comment....
To make sure we all understand your question...
Is your question how many (eukaryote) species are currently living? or How many (eukaryote) cells are currently living??
Just a hint to answer the question
Micheal Lynch, in his book (On the Origin of Genome Architecture) at page 3, Box 1.1 tries to answer the question How much DNA is there on earth?. He ends up with an estimation of a total length of DNA on earth of $10^{24}$ km for procaryotes, $10^{25}$ km for eukaryote (of which $\frac{1}{1000}$% is accounted to humans). This sums up to a total DNA length of $10^{12}$ light-years, or 10 times the diameter of the known universe!
In his calculations, he estimates that the total number of procaryote cells at $10^{30}$ (citing Whitman et al. 1998 as you did). He estimates the total number of eukaryote species to $10^7$, i.e. 6 times the number of known eukaryote species. However, he doesn't directly give any reference for this estimate but he refers to different chapters in the book that contain lots of references.
...I hope that helps...
The following is multiple choice question (with options) to answer.
More than half of all known organisms are what? | [
"mammals",
"enzymes",
"insects",
"spiders"
] | C | The majority of arthropods are insects (Class Insecta). In fact, more than half of all known organisms are insects. There may be more than 10 million insect species in the world, although most of them have not yet been identified. In terms of their numbers and diversity, insects clearly are the dominant animals in the world. |
SciQ | SciQ-272 | biochemistry, metabolism, endocrinology, glucose
This reaction is highly exergonic which means its preferred direction is to the right side. To change this and make Pyruvate from Lactate you need an excess of NAD+ which usually only happens in the liver.
There is also an epidimiologic study available showing a strong correlation between elevated blood lactate levels and diabetes type II: "Association of blood lactate with type 2 diabetes: the Atherosclerosis Risk in Communities Carotid MRI Study."
The following is multiple choice question (with options) to answer.
For what purpose does liver use the excess carbohydrate? | [
"to synthesize glycogen",
"convert starches",
"process sugar",
"dilute carbohydrates"
] | A | Obesity With obesity at high rates in the United States, there is a public health focus on reducing obesity and associated health risks, which include diabetes, colon and breast cancer, and cardiovascular disease. How does the food consumed contribute to obesity? Fatty foods are calorie-dense, meaning that they have more calories per unit mass than carbohydrates or proteins. One gram of carbohydrates has four calories, one gram of protein has four calories, and one gram of fat has nine calories. Animals tend to seek lipid-rich food for their higher energy content. Greater amounts of food energy taken in than the body’s requirements will result in storage of the excess in fat deposits. Excess carbohydrate is used by the liver to synthesize glycogen. When glycogen stores are full, additional glucose is converted into fatty acids. These fatty acids are stored in adipose tissue cells—the fat cells in the mammalian body whose primary role is to store fat for later use. The rate of obesity among children is rapidly rising in the United States. To combat childhood obesity and ensure that children get a healthy start in life, in 2010 First Lady Michelle Obama launched the Let’s Move! campaign. The goal of this campaign is to educate parents and caregivers on providing healthy nutrition and encouraging active lifestyles in future generations. This program aims to involve the entire community, including parents, teachers, and healthcare providers to ensure that children have access to healthy foods—more fruits, vegetables, and whole grains—and consume fewer calories from processed foods. Another goal is to ensure that children get physical activity. With the increase in television viewing and stationary pursuits such as video games, sedentary lifestyles have become the norm. Visit www. letsmove. gov to learn more. |
SciQ | SciQ-273 | star, luminosity, helium
Title: What is the most appropriate way to estimate the helium composition of a star? Say we have to estimate the helium content in Proxima Centauri.
We begin by calculating the content of helium in the Sun (source): $24.85$% of $2.10^{30}$ kg.
Mostly all the energy is generated due to the product of nuclear fusion of hydrogen into helium by way of the proton–proton (PP) chain mechanism and the luminosity of Proxima Centauri is $0.00005\ L_☉$.
Thus, would it be a good approximation to say that the helium content is $0.00005 * 0.2485 * 2 * 10^{30}$?
Would you suggest a better way of estimating the helium content? Nearly all the helium in the photosphere of the sun comes from the helium in the interstellar gas that collapsed to form the sun. That helium was produced shortly after the Big Bang (in about the first 20 minutes) while the universe was hot and dense enough for hydrogen to fuse to helium. That produces a universe in which ordinary matter is about 25% helium and 75% hydrogen. (by mass) Over the eons, the gas is enriched in helium somewhat by previous stars to about 27% helium.
The outer layers of the sun still have this 25%-75% composition. Some of the helium has settled under gravity, reducing the composition of the photosphere to your 24.85% helium. The core is enriched in helium by fusion reactions. It isn't constant. The outer core is about 30% helium. The inner core has as much as 65% helium. The average composition is about 28% helium, only slightly more than what it started with.
Proxima Centauri is fully convective, which means that helium from the core gets mixed up through the whole star. But it is such a dim candle that it has hardly produced any more helium than when it formed: about 27%.
So for any star, no matter how bright or dim (with a few exceptions) the helium composition is about 25%, or a little more.
The following is multiple choice question (with options) to answer.
Saturn is made mostly of helium and what else? | [
"hydrogen",
"hydrogen",
"nitrogen",
"carbon"
] | A | Saturn’s composition is similar to Jupiter's. The planet is made mostly of hydrogen and helium. These elements are gases in the outer layers and liquids in the deeper layers. Saturn may also have a small solid core. Saturn's upper atmosphere has clouds in bands of different colors. These clouds rotate rapidly around the planet. But Saturn has fewer storms than Jupiter. Thunder and lightning have been seen in the storms on Saturn ( Figure below ). |
SciQ | SciQ-274 | organic-chemistry, nomenclature, hydrocarbons
Title: Chain with double bond or triple bond
In this hydrocarbon there can be two main chains: one with two double bonds and one with a double and a triple bond
Both main chains contain seven carbon atoms.
Which will be considered correct and why? According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), as already mentioned in the question, the first relevant criterion to be considered in choosing a principal chain is the length of the chain.
When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached:
P-44.4.1 If the criteria of P-44.1 through P-44.3, where applicable, do not effect a choice of a senior parent structure, the following criteria are applied successively until there are no alternatives remaining. (…)
The senior ring, ring system, or principal chain:
(a) has the greater number of multiple bonds (P-44.4.1.1);
(b) has the greater number of double bonds (P-44.4.1.2);
(…)
(h) has the lower locant for an attached group expressed as a suffix (P-44.4.1.8);
(…)
Since both possible chains in this case have two multiple bonds, Rule (a) is not enough to make a choice.
According to Rule (b), the principal chain is the hepta-1,6-diene because it has the greater number of double bonds.
Therefore, the preferred IUPAC name (PIN) is 4-(prop-2-yn-1-yl)hepta-1,6-diene.
The following is multiple choice question (with options) to answer.
What are alkenes organic compounds that contain one or more double or triple bonds between carbon atoms described as? | [
"unsaturated",
"saturated",
"insulated",
"strong"
] | A | Alkenes Organic compounds that contain one or more double or triple bonds between carbon atoms are described as unsaturated. You have likely heard of unsaturated fats. These are complex organic molecules with long chains of carbon atoms, which contain at least one double bond between carbon atoms. Unsaturated hydrocarbon molecules that contain one or more double bonds are called alkenes. Carbon atoms linked by a double bond are bound together by two bonds, one σ bond and one π bond. Double and triple bonds give rise to a different geometry around the carbon atom that participates in them, leading to important differences in molecular shape and properties. The differing geometries are responsible for the different properties of unsaturated versus saturated fats. Ethene, C2H4, is the simplest alkene. Each carbon atom in ethene, commonly called ethylene, has a trigonal planar structure. The second member of the series is propene (propylene) (Figure 20.7); the butene isomers follow in the series. Four carbon atoms in the chain of butene allows for the formation of isomers based on the position of the double bond, as well as a new form of isomerism. |
SciQ | SciQ-275 | bond
Title: Types of bonds in a molecule For example in dinitrogen pentoxide, $\ce{N2O5}$, covalent as well as coordinate bonds (type of covalent bonds) are present, but it appears that it contains only covalent bond.
What is a proper method to find out which type of bonds are present in a molecule? Electrovalent bonds are easiest to identify. If a compound is made up of a metal and non-metal/non-metallic radical (like carbonate), then, 99.99% times, it contains electovalent bond. If a compound is made up of 2 or more non-metals/non-metallic radicals, then it contains covalent bond. Coordinate covalent bonds appear mostly with compounds containing Hydrogen element. To identify the coordinate covalent bonds, you can draw the branched structural formula of the compound and see if the shared pair of electrons are coming from the same molecule.
The following is multiple choice question (with options) to answer.
Electrons in covalent compounds are shared between the two atoms, unlike the case in what type of bonds? | [
"horizontal bonds",
"weak bonds",
"soluble bonds",
"ionic bonds"
] | D | The two materials do have at least one thing in common. The atoms in the materials are held together by covalent bonds. These bonds consist of electrons shared between two or more atoms. Unlike ionic bonds, where electrons are either lost or gained by an atom to form charged ions, electrons in covalent compounds are shared between the two atoms, giving rise to properties that are quite different from those seen in ionic materials. |
SciQ | SciQ-276 | fluid-dynamics, pressure, drag
Title: What is the resistance of an object travelling through static fluid at different pressures? I'm interested in the resistance a body feels as it travels through a static fluid in a tube (of a fixed radius), at different pressures.
I would assume that as the pressure is reduced, the resistance will also be decreased. Does this relate to the Drag Force equation, or is there a better explanation, such as Bernoulli? As mentioned in one of the comments, if the fluid is incompressible (i.e. - has constant density) then the absolute level of the pressure will not affect the drag.
However if the fluid is a gas, then the pressure and density will be strongly related (directly proportional for ideal gases). And the density of the fluid enters into the equation for the dynamic pressure, so it does affect the drag.
For a constant drag coefficient, the drag will be directly proportional to the density, so for streamlined shapes at sufficiently large Reynolds' numbers, the drag will be approximately proportional to the pressure.
This should be true even if the Mach number of the flow is small enough for the incompressible flow equations to be used.
The following is multiple choice question (with options) to answer.
What is the resistance of a liquid to flow called? | [
"turbulence",
"elasticity",
"permeability",
"viscosity"
] | D | Viscosity (η) is the resistance of a liquid to flow. Some liquids, such as gasoline, ethanol, and water, flow very readily and hence have a low viscosity. Others, such as motor oil, molasses, and maple syrup, flow very slowly and have a high viscosity. The two most common methods for evaluating the viscosity of a liquid are (1) to measure the time it takes for a quantity of liquid to flow through a narrow vertical tube and (2) to measure the time it takes steel balls to fall through a given volume of the liquid. The higher the viscosity, the slower the liquid flows through the tube and the steel balls fall. Viscosity is expressed in units of the poise (mPa·s); the higher the number, the higher the viscosity. The viscosities of some representative liquids are listed in Table 11.4 "Surface Tension, Viscosity, Vapor Pressure (at 25°C Unless Otherwise Indicated), and Normal Boiling Points of Common Liquids" and show a correlation between viscosity and intermolecular forces. Because a liquid can flow only if the molecules can move past one another with minimal resistance, strong intermolecular attractive forces make it more difficult for molecules to move with respect to one another. The addition of a second hydroxyl group to ethanol, for example, which produces ethylene glycol (HOCH2CH2OH), increases the viscosity 15-fold. This effect is due to the increased number of hydrogen bonds that can form between hydroxyl groups in adjacent molecules, resulting in dramatically stronger intermolecular attractive forces. |
SciQ | SciQ-277 | atoms
Title: Why is the atomic mass unit less than the mass of both a neutron and a proton? The atomic mass unit is $1.6605 \times 10^{-27}$ kg.
This is less than the mean of the masses of 6 protons and 6 neutrons.
How do we account for the lower mass ?
My understanding is that some of the mass is in the form of energy somewhere, in the bonding maybe or in the kinetic energy.
Can someone clarify where this mass is please ? The source of the discrepancy is the mass defect, which is described in the article below as :
The difference between the sum of the masses of the components and the measured atomic mass is called the mass defect of the nucleus. Just as a molecule is more stable than its isolated atoms, a nucleus is more stable (lower in energy) than its isolated components. Consequently, when isolated nucleons assemble into a stable nucleus, energy is released. According to Equation 4, this release of energy must be accompanied by a decrease in the mass of the nucleus.
The equation four referenced is just E=mc^2. When these nucleons form carbon-12, which is the reference isotope for the definition of the amu, the mass defect appears, as you mentioned, by conversion to binding energy.
https://chem.libretexts.org/Courses/Grand_Rapids_Community_College/CHM_120_-_Survey_of_General_Chemistry/2%3A_Atomic_Structure/2.07_Mass_Defect_-_The_Source_of_Nuclear_Energy
The following is multiple choice question (with options) to answer.
The mass of atoms is based on the number of protons and neutrons in what? | [
"components",
"nucleus",
"molecules",
"electrons"
] | B | Atoms have a mass that is based largely on the number of protons and neutrons in their nucleus. |
SciQ | SciQ-278 | zoology, species-identification, marine-biology, invertebrates
Title: Species identification - greenish blue ocean worm (nudibranch?) in Perhentian Islands, Malaysia We found this on a beach at the Perhentian Islands, Malaysia in March, 2016 and cannot identify it. It's some sort of worm-type creature with many legs and bluish back about 15cm long. The legs undulated along the body as it swam.
back:
belly side: It's hard to identify from the photos provided, but I think it is Chloeia flava (a species of polycaete worm, within the phylum Annelida), also known in English as the "Golden Fireworm".
The size is roughly similar to what you describe (they are typically about 7-10 cm long). The individual you observed looks like it lives in sandy bottom environments (not a typical environment for a nudibranch), and this worm does also. It is commonly found all across the warmer Indo-Pacific as well, and looks like the individual observed in your photo.
If it is not this species, I think it is another species of the same family, Amphinomidae.
The following is multiple choice question (with options) to answer.
Where do polychaete worms live? | [
"in tide pools",
"in coral reefs",
"attached to marine life",
"the ocean floor"
] | D | Annelids called polychaete worms live on the ocean floor. They may be filter feeders, predators, or scavengers. The amazing feather duster worm in Figure below is a polychaete that has a fan-like crown of tentacles for filter feeding. |
SciQ | SciQ-279 | ecology, statistics, species, species-distribution
Title: How do I compare the variance of a distribution of species in one area versus another? It's possible that this question is better suited for stack overflow, but I think the ecologists on this site might be better equipped to answer it.
I'm trying to study two geographically-isolated populations of the same species. Inspecting the distributions, I see that both are bimodal (there's some seasonality to their occurrence), but the peaks in one population are much higher and much narrower (i.e., the variance of the local peaks is smaller).
What sort of statistical test would be appropriate to determine whether these differences are significant? These are just some preliminary ideas...
I think you should look at the seasonal distributions separately, since the bimodal distribution is the outcome of two fairly separate processes. The two distributions might also be controlled by different mechanisms, so that e.g. winter distributions might be more sensitive to yearly climate. If you want to look at population differences and reasons for these I think it is therefore more useful to study seasonal distributions separately. An exploratory analysis could be to compare distribution percentiles (north/south and east/west coordinates) to look at range edges, or to use a fixed number of edge observations to establish borders. The weighted centre-point of population distributions can be used to look for differences in overall position. If you have grid occurences, percentage overlap between species/populations could maybe also be useful.
If you haven't already, you look also look at Maxent, which is a widely used software for modelling species distributions and habitats. Look at Elith et al. (2011) for an overview. If you want to look at changes over time (even if this doesn't seem to be your main point) you should also check out dynamic occupancy models that use occurrence records to model species distribution while taking detectability into account, e.g. MacKenzie et al. (2009).
The following is multiple choice question (with options) to answer.
What is the study of how and why plants and animals live where they do? | [
"lithography",
"geomorphology",
"heredity",
"biogeography"
] | D | Biogeography is the study of how and why plants and animals live where they do. It provides more evidence for evolution. Let’s consider the camel family as an example. |
SciQ | SciQ-280 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
Muscles that position the pectoral girdle are located either on the anterior thorax or on this? | [
"posterior thorax",
"analogous thorax",
"posterior thorax",
"inferred thorax"
] | A | Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax (Figure 11.22 and Table 11.8). The anterior muscles include the subclavius, pectoralis minor, and serratus anterior. The posterior muscles include the trapezius, rhomboid major, and rhomboid minor. When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly. |
SciQ | SciQ-281 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
What are the two major types of seed plants called? | [
"deciduous and evergreen",
"flowers and fruits",
"perennials and annuals",
"gymnosperms and angiosperms"
] | D | The two major types of seed plants are the gymnosperms (seeds in cones) and angiosperms (seeds in ovaries of flowers). Figure below shows how the seeds of gymnosperms and angiosperms differ. Do you see the main difference between the two seeds? The angiosperm seed is surrounded by an ovary . |
SciQ | SciQ-282 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
What do we call the energy-rich product of photosynthesis? | [
"sugar",
"insulin",
"glucose",
"chloride"
] | C | Glucose is the energy-rich product of photosynthesis, a universal food for life. It is also the primary form in which your bloodstream delivers energy to every cell in your body. |
SciQ | SciQ-283 | biochemistry, gas-laws
Title: What is the state of aggregation (gas, liquid) of oxygen in blood? Atmospheric oxygen is in O2 and a gas. Then we inhale the air, our efficient lungs do the magic to filter out the oxygen and push them into the blood stream.
When we say hemo and globin transport the oxygen using the iron ions. In what state oxygen is transported in the blood? as a gas or a liquid or an ion? It is hard for me to conceive of the idea that oxygen would be in gaseous form in the blood. "GAS in blood?" e.g. Arterial Blood Gas Test
Also, how does the lungs convert the gas into something that is compatible to be in blood?
References:
Amount of Oxygen in the Blood Regarding the state of oxygen in blood: It is in solution in the blood plasma (which mostly consists of water), in the form of single molecules. Think of water which you leave exposed to air: carbon dioxide will be captured and dissolved (along with the other gases in air), but these molecules are not gaseous or liquid, but rather "in solution", which is different from the "classical" states.
Back to oxygen: As your reference already states, most of the oxygen in solution will bind to hemoglobin. The actual state of oxygen in that complex has been debated, but it is believed to be reduced by the hemoglobin iron to the superoxide anion, coordinated to Fe$^{3+}$. See Wikipedia on this.
Also, the lungs do not "convert" the atmospheric oxygen to anything, they rather allow, due to their very large surface area, the quick exchange of oxygen/carbon dioxide in solution and in the air.
The following is multiple choice question (with options) to answer.
How is oxygen transferred into the bloodstream? | [
"brain diffusion",
"hard diffusion",
"mean diffusion",
"simple diffusion"
] | D | The oxygen enters the bloodstream from the alveoli , tiny sacs in the lungs where gas exchange takes place ( Figure below ). The transfer of oxygen into the blood is through simple diffusion. |
SciQ | SciQ-284 | mycology
Does this mean that not only is going to the swimming pool not a cure of fungal infections, but it is actually the cause? Well, maybe not. While the articles show that there is a larger incidence of fungal infections among swimmers, they only show correlation, not causality. People who partake in sports activities have a bigger chance of having these infections than the general public. These are also the people who are more likely to go swimming.
To settle the matter for good, we need an article named "Prevalence of fungal infections among occasionally swimming couch potatoes" :-)
The following is multiple choice question (with options) to answer.
Ringworm and athlete's foot are human diseases caused by what simple organisms? | [
"bacteria",
"viruses",
"fungi",
"insects"
] | C | Fungi are simple eukaryotic organisms that consist of one or more cells. They include mushrooms and yeasts. Human diseases caused by fungi include ringworm and athlete’s foot. Both are skin diseases that are not usually serious. A ringworm infection is pictured below ( Figure below ). A more serious fungus disease is histoplasmosis. It is a lung infection. Though fungal infections can be annoying, they are rarely as serious or deadly as bacterial or viral infections. |
SciQ | SciQ-285 | of photon picture of light ( b ) momentum versus velocity when mass is in. Taken positive moving body is the product of mass m moving with momentum! Narendra Awasthi MS Chauhan for its complete description we can measure mass of an object of mass velocity. Pandey Sunil Batra HC Verma Pradeep Errorless, are defined in terms of its mass velocity... B ) a car and a direction for its complete description is measured in meter /.! Sunil Batra HC Verma Pradeep Errorless Google: momentum define the term Linear momentum meters per second ) elastic. By a moving body is known as momentum of an object to do work direction its. Of 0.10 kgm/s in an object to do work ( CBSE 2012 ) Answer: SI unit?! Impulse, and Sports a scalar or vector quantity, requiring the specification of both a and... Units for these derived quantities, called derived quantities, called derived quantities, called derived are! ; Harsh Srivastava 2 years, 8 months ago between ( any two ) elastic inelastic... ; Harsh Srivastava 2 years, 8 months ago mass and velocity Expert ( 1.4k points ).... P=Mv ) are still used in this article momentum define the term impulse, and momentum asked 6. Kg, and momentum ; the SI unit. versus velocity when mass is fixed of both a and... Momentum, and that of velocity is measured in terms of its mass -1... Topperlearning.Com | giemys momentum of a body is the second: Google: momentum define the term,... 2014 ) or define one newton of force is a vector quantity of... Its capacity of doing work of quantity equations years, 8 months ago its and! Quantity equations ( P=mv ) ( any two ) elastic and inelastic collision: momentum the. Torques are taken positive is defined as the define momentum and its si unit of an is!, Linear momentum = mass x velocity - it is a vector quantity which possess both magnitude and direction. Base quantities via a system of quantity equations N s ) is the product of mass and of. Points ) 1/ in terms of the body when mass is measured in kg and velocity is.! X velocity - it is defined as product of mass and velocity ( P=mv )
The following is multiple choice question (with options) to answer.
What is the measure of the change in the velocity of a moving object called? | [
"compression",
"pressurization",
"transmission",
"acceleration"
] | D | A car’s gas pedal, like the one in Figure below , is sometimes called the accelerator. That’s because it controls the acceleration of the car. Pressing down on the gas pedal gives the car more gas and causes the car to speed up. Letting up on the gas pedal gives the car less gas and causes the car to slow down. Whenever an object speeds up, slows down, or changes direction, it accelerates. Acceleration is a measure of the change in velocity of a moving object. Acceleration occurs whenever an object is acted upon by an unbalanced force. |
SciQ | SciQ-286 | virus, antibiotics
Title: What are the positive effects of wrongful antibiotic use on a viral infection? I categorically accept that bacteria differ from viruses; so antibiotics DON'T help in viral infections. I also read this and this; so no need to explain this. I've read about the negative effects (eg exacerbation of antibiotic resistance); I ask only about the positive effects here, and NOT for reasons to exploit antibiotics for infections not due bacteria.
Yet I myself have witnessed that some people with viral infections feel better after wrongly taking antibiotics? and so asked about this first on Cognitive Sciences SE.
Initially, I suspected only some placebo effect, but this enlightened me on the side benefits of antibiotic consumption for a viral infection and motivated this question, now that my original question on psychology has revealed the relevance of biology. There are indeed antibiotics which have immunomodulatory side-effects, these are mostly from the class of macrolide antibiotics (erythromycin, clarithromycin, roxithromycin, azithromycin) and to some degree from the tetracyclines. Beta-lactam antibiotics (as Penicillin or Ampicillin) have not been shown to be immunomodulatory, but they are among the most commonly used. See reference 1 for more details.
The biggest effect has been shown on pulmonary diseases such as cystic fibrosis or diffuse panbrochiolitis (see reference 2).
Although the exact mechanism of action is not known, Macrolides are know to downregulate the inflammatory cascade and that the reduce the strong cytokine expression of some viral infections. However, these regulatory effects are relatively weak if you compare them to the anti-inflammatory properties of corticosteroids. So the question here is if the advantages are really sufficient compared to the problems, which an unnecessary use of antibiotics may cause. See reference 3 and the references in the paper for more details here.
Antibiotics may be useful to fight bacterial secondary or superinfections which accompany a virus infection.
References:
Immunomodulatory Properties of Antibiotics
Macrolide activities beyond their antimicrobial effects: macrolides
in diffuse panbronchiolitis and cystic fibrosis
Macrolide Therapy in Respiratory Viral Infections
The following is multiple choice question (with options) to answer.
What is the usual treatment for acute bronchitis? | [
"antibiotics",
"pesticides",
"physical therapy",
"surgery"
] | A | Bronchitis is an inflammation of the bronchi, the air passages that conduct air into the lungs. The bronchi become red and swollen with infection. Acute bronchitis is usually caused by viruses or bacteria, and may last several days or weeks. It is characterized by a cough that produces phlegm, or mucus. Symptoms include shortness of breath and wheezing. Acute bronchitis is usually treated with antibiotics. |
SciQ | SciQ-287 | evolution, taxonomy
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild.
That last part takes care of the ligers and tiglons. But what if we consider plants? Under the definition I just gave, most grasses (around 11,000 species) would have to be considered as one species. In the wild, most grasses will freely pollinate related species and produce hybrid seed, which germinates. You might then think we could just modify the definition to specify that the offspring must be fertile (i.e. able to reproduce with one another)...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild to produce fertile progeny.
Unfortunately, the situation is still more complicated (we've barely started!). Often wild hybridisation events between plants lead to healthy, fertile offspring. In fact common wheat (Triticum aestivum) is a natural hybrid between three related species of grass. The offspring are able to breed freely with one another.
Perhaps we could account for this by taking into account whether the populations usually interbreed, and whether they form distinct populations...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of populations or meta-populations of related individuals that resemble one another, are able to breed among themselves, but do tend not to breed freely with members of another species in the wild to produce fertile progeny.
The following is multiple choice question (with options) to answer.
What are generally divided into prosimian and non-prosimian? | [
"primates",
"rodents",
"insects",
"carnivores"
] | A | Primates are generally divided into prosimian and non-prosimian primates. |
SciQ | SciQ-288 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
The creation and destruction of oceanic crust is the reason what moves? | [
"continents",
"animals",
"oceans",
"planets"
] | A | In some places, the oceanic crust comes up to a continent. The moving crust pushes that continent away from the ridge axis as well. If the moving oceanic crust reaches a deep sea trench, the crust sinks into the mantle. The creation and destruction of oceanic crust is the reason that continents move. |
SciQ | SciQ-289 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
What is the concept by which two species within the same area to coexist by adapting by developing different specializations? | [
"character development",
"character displacement",
"feature displacement",
"character concept"
] | B | Looking at different types of competition, ecologists developed the competitive exclusion principle . The principle states that species less suited to compete for resources will either adapt, move from the area, or die out. In order for two species within the same area to coexist, they may adapt by developing different specializations. This is known as character displacement . An example of character displacement is when different birds adapt to eating different types of food. They can develop different types of bills, like Darwin’s Finches ( Figure below ). Therefore, competition for resources within and between species plays an important role in evolution through natural selection . |
SciQ | SciQ-290 | electromagnetism, electricity, energy-conservation, perpetual-motion
Title: Auto spinning turbine generator This might be dumb question but I'm so curious to know if this actually works or is impossible. I was researching how you could generate electricity from magnets and copper wire and also have read how the hydroelectric generators work and it seems like they share the same concept. So if we are able to generate electricity by moving the turbine with water then why not have a some sort of motor which will make the turbine spin by getting power from the generator. I mean first there needs to be some sort of initial mechanical source to make the turbine spin then once the turbine starts moving and the generator gives power, the other motor gets power and it will take over the spinning of the turbine. So that way it will auto spin itself and basically means free energy. Can someone explain why this is not possible? As with virtually all perpetual motion machines, the reason becomes obvious once you consider the thermodynamic efficiency of the components involved. No turbine is 100% efficient, and also no motor is 100% efficient. This means that out of the initial energy you put in to make the turbine spin, only a certain percentage will be converted to electricity, with the rest being converted to heat. Then, out of that electricity, only a certain percentage is converted to mechanical energy to drive the turbine again. Then we go round again, losing some of that energy to heat until pretty soon the whole thing stops turning.
Of course, it would work just fine if you had an engine or a turbine that was more than 100% efficient, putting out more energy than you have to put in to drive it. But then, that's exactly the reason why we know that efficiencies over 100% are impossible: we observed that perpetual machines seem to be impossible, and from that Carnot derived his thermodynamic limits. The resulting theory has stood the test of time since the 19th century.
The following is multiple choice question (with options) to answer.
A turbine that spins a generator will produce? | [
"light",
"electricity",
"solar energy",
"magnetic fields"
] | B | You can follow the operation of an electricity-generating fission reactor in the image above. The reactor core is submerged in a pool of water. The heat from the fission reaction heats the water, which is pumped into a heat exchange container. There the heated water boils the water in the heat exchanger. The produced steam is forced through a turbine that spins a generator and produces electricity. After the water passes through the turbine, it is condensed back to liquid water and pumped back to the heat exchanger. |
SciQ | SciQ-291 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
Meiosis in the sporophyte produces haploid cells called what? | [
"fibers",
"spores",
"seeds",
"ions"
] | B | |
SciQ | SciQ-292 | aqueous-solution, solubility, phase
Whereas the IUPAC Gold Book defines a chemical reaction as:
A process that results in the interconversion of chemical species.
One aspect of solvation vs. reaction that may seem confusing is the solubility of ionic species. Even though $\ce{NaCl}$ becomes $\ce{Na+}$ and $\ce{Cl-}$ in an aqueous solution, this does not constitute a chemical reaction as defined above, and we say that $\ce{NaCl}$ is soluble in water. The same is true of your example of $\ce{H2SO4}$; even though it dissociates in water, it is not converted to a new chemical compound. One way to think of this is if you remove the solvent, the solute should typically resume to it's original form. From our previous example, if we evaporate the water from our aqueous solution of $\ce{Na+}$ and $\ce{Cl-}$, we just get the solid $\ce{NaCl}$ back.
Your examples of solubility in hydrochloric acid are a bit complex because that is a two-component system of water and $\ce{HCl}$. All of the compounds you discuss are water soluble and it doesn't matter if the $\ce{HCl}$ is there or not. One slight exception in your examples is ethylamine. Ethylamine itself is miscible with water, but many higher molecular weight amines are not water soluble, but are soluble in hydrochloric acid. In this case, the $\ce{H+}$ from $\ce{HCl}$ protonates the amine, making the hydrochloride salt. This is still an example of solubility however, as once you remove the solvent, you are left with the original compound, in this case the amine.
The following is multiple choice question (with options) to answer.
In this type of reaction, an element replaces another element in a compound, and the element is in any state of matter but is not an ion? | [
"replication reaction",
"double-replacement reaction",
"single-replacement reaction",
"polar reaction"
] | C | A single-replacement reaction is one in which an element replaces another element in a compound. An element is in either the solid, liquid, or gas state and is not an ion. The example below shows the reaction of solid magnesium metal with aqueous silver nitrate to form aqueous magnesium nitrate and silver metal. |
SciQ | SciQ-293 | cell-biology, organelle
Title: Univocal identifying of a plant cell We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts in order to justify my statement.
Now in the exercise, we first had to identify the parts of a cell (which was shown in form of an image) and then in part b) reason whether it was an animal or plant cell.
I had identified a chloroplast and a vacuole and stated that the only cell with this organelles was the plant cell. My teacher answered that I had missed the fact, that the cell had also a cell wall (which is indeed a difference between plant and animal cells).
My question is
Is the fact that the cell had a cell wall necessary in my argumentation, i.e. are there other cells having chloroplasts and a vacuole without being a plant cell?
Could you provide a source which supports, or doesn't support my statement so that I can show it to my teacher?
Thanks in advance Your teacher is right, chloroplasts and vacuoles are not sufficient to define a plant cell.
Amoeba have both chloroplasts (McFadden et al, PNAS, 1994) and vacuoles (Day, J. Morphology, 1927) but they are not plants - and they do not have a cell wall.
Sea slugs eat algae and can "steal" their plastids and keep them working for weeks/months, effectively becoming photosynthetic animals for a while. This is called kleptoplastidy (Pillet, Mob. Genet. Elements, 2013).
The following is multiple choice question (with options) to answer.
What are the two distinct types of cells found in the animal kingdom? | [
"bacteria and eukaryotes",
"chromosomes and eukaryotes",
"prokaryotes and eukaryotes",
"DNA and Eukaryotes"
] | C | |
SciQ | SciQ-294 | bond, metal, ionic-compounds, covalent-compounds
Title: Metallic character of bonds? Why in discussions of percent character of bonds, are only ionic and covalent bondings discussed? Do bonds not have a partial metallic character, and are either metallic and ionic-covalent? One could think of the Fermi surface and conduction bands as an expression of the degree of metallic bonding, where metals such as aluminum or silver have overlapping empty and filled bands, allowing for electrical conduction, while semiconductors have a small gap between filled and conduction bands, offering more resistance.
As @Mithoron states, metallic bonding is a bulk property. Metals behave differently as nanoparticles -- for example, bulk silver is reflective, but nanometer particles of it are black, as in photographs.
The following is multiple choice question (with options) to answer.
What category of elements are chacterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility? | [
"noble gases",
"halogens",
"nonmetals",
"metals"
] | D | Metallic Solids Metals are characterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility. Every lattice point in a pure metallic element is occupied by an atom of the same metal. The packing efficiency in metallic crystals tends to be high, so the resulting metallic solids are dense, with each atom having as many as 12 nearest neighbors. Bonding in metallic solids is quite different from the bonding in the other kinds of solids we have discussed. Because all the atoms are the same, there can be no ionic bonding, yet metals always contain too few electrons or valence orbitals to form covalent bonds with each of their neighbors. Instead, the valence electrons are delocalized throughout the crystal, providing a strong cohesive force that holds the metal atoms together. |
SciQ | SciQ-295 | botany, terminology, nomenclature
Regnum Animale: the animals;
Regnum Vegetabile: the plants;
Regnum Lapideum: the minerals (you read it right).
Note that, in this classification, "animals" correspond to what nowadays we call animals and protozoans, and "plants" correspond to what nowadays we call plants, algae, fungi and bacteria.
You have to keep in mind that this book was first published in 1735, well before the evolutionary biology being proposed in the XIX century and established in the XX century. Therefore, it is a book published when fixism was the current paradigm, full of mentions to the scala naturae.
So, the plants (as well as the animals) showed a continuum of species, going to the lower plants (the bacteria) to the higher plants (the flowering ones). It's worth mentioning again that, by that time, bacteria were plants: Phylum Schyzophyta, to be more precise.
Thus, we have "lower plants" and "higher plants", "lower animals" and "higher animals", as well as "lower minerals" and "higher minerals"!
Unfortunately, this terminology is so embedded in the biological sciences that even today, as I mentioned, we struggle to get rid of it.
Just drop "higher plants", whatever it means
As your Wikipedia link says, "higher plants" is a synonym of vascular plants. However, there are a lot of problems here:
First, this is a remnant of the scala naturae and, just because of that, should be avoided. Think of it as a meaningless term, just like "more evolved organism".
Second, there is no clear and indisputable definition of what is a "higher" plant. Some authors used to define the "higher plants" as the Angiosperms only, or the seed plants (Angiosperms + Gymnosperms), or the vascular plants (Angiosperms, Gymnosperms and Pteridophyta).
For instance, in lusophone biology books, it was very common a division in three groups:
lower plants: bacteria and algae;
intermediate plants: bryophytes and pteridophytes;
higher plants: gymnosperms and angiosperms.
The following is multiple choice question (with options) to answer.
Angiosperms are also known as what? | [
"uncommon plants",
"dry plants",
"dead plants",
"flowering plants"
] | D | Introduction Plants are as essential to human existence as land, water, and air. Without plants, our day-to-day lives would be impossible because without oxygen from photosynthesis, aerobic life cannot be sustained. From providing food and shelter to serving as a source of medicines, oils, perfumes, and industrial products, plants provide humans with numerous valuable resources. When you think of plants, most of the organisms that come to mind are vascular plants. These plants have tissues that conduct food and water, and they have seeds. Seed plants are divided into gymnosperms and angiosperms. Gymnosperms include the needle-leaved conifers—spruce, fir, and pine—as well as less familiar plants, such as ginkgos and cycads. Their seeds are not enclosed by a fleshy fruit. Angiosperms, also called flowering plants, constitute the majority of seed plants. They include broadleaved trees (such as maple, oak, and elm), vegetables (such as potatoes, lettuce, and carrots), grasses, and plants known for the beauty of their flowers (roses, irises, and daffodils, for example). While individual plant species are unique, all share a common structure: a plant body consisting of stems, roots, and leaves. They all transport water, minerals, and sugars produced through photosynthesis through the plant body in a similar manner. All plant species also respond to environmental factors, such as light, gravity, competition, temperature, and predation. |
SciQ | SciQ-296 | human-biology, microbiology
Title: How much weight/volume do microbes occupy within the human body? Microorganisms constitute the bulk of all the biomass on Earth. I weighed myself yesterday, and wondered how much less I would weigh if I were completely free of bacteria and microbes, inside and out.
Approximately how much weight and volume do microbes occupy within the average human body? How were these values obtained? @AlanBoyd's calculations are reasonable, I think the estimate is off though. The human microbome includes other bacteria which are not necessarily E.coli equivalent.
The human microbome projects give estimates that microbes are 1-3% total body mass. i.e. several pounds of bacteria.
The GI tract alone has most of the microbome mass - faeces is ~60% intestinal flora/fauna by dry weight, which for many adults alone must be hundreds of grams at any given moment.
The following is multiple choice question (with options) to answer.
An estimated 100 trillion of these live in the gut of an average person? | [
"pathogens",
"algae",
"bacteria",
"viruses"
] | C | It is estimated that 100 trillion bacteria live in the gut. This is more than the human cells that make up you. It has also been estimated that there are more bacteria in your mouth than people on the planet. There are over 7 billion people on the planet. |
SciQ | SciQ-297 | evolution, mammals, marine-biology
The question remains: why? The most likely explanation is that cetaceans evolved to exploit an unfilled ecological niche or adapted to new niches that formed as a result of plate tectonics or other types of environmental changes that occurred 50-55 million years ago. The niche describes all of the living and non-living resources needed by an organism to survive. Although land-based mammals were increasing in diversity, few or none were present in the oceans. The basic hypothesis is that the early whale-like artiodactyls, like Indohyus and Pakicetus were land-based (terrestrial) mammals that spent most of their time near the water's edge. Over time, they adapted to the niches in the ocean. Fossils like Ambulcetus and Rodhocetus showed clear evidence of swimming ability, with flattened tails and the enlarged rear feet. In addition, the nostrils shifted from the front of the face to the top of the head, which we recognize as the blowhole.
The shift to the aquatic habitat allowed these species to exploit resources that were not available to land-based mammals, thereby reducing competition for the resources. Reduced competition allows more individuals to survive and reproduce.
Similar scenarios are very likely for other marine mammals, such as seals or manatees. They evolved to take advantage of ecological niches that were not filled by other organisms. This basic concept, evolving to fill available niches, is a common outcome of the evolutionary process.
The of adaptation of cetaceans and other mammals to the oceans may be similar to that of the hippopotamus. Hippos spend most of their time in the water, and they show many adaptations that allow them to live in the aquatic environment. The eyes and nostrils of the hippo are high on the head, which allows them to remain almost entirely submerged but still see and smell, as shown below.
(Hippo photo by Johannes Lunberg, Flickr Creative Commons.)
Hippos feed underwaters, they are heavy enough to walk on the bottom of the river, and the mate and give birth underwater. The young can suckle underwater. Clearly, hippos seem to be another mammal that is "returning to water." Similar types of processes must have occurred in cetaceans for them to adapt to the marine habitat.
The following is multiple choice question (with options) to answer.
The ability to regulate what, which is possessed by mammals, was an advantage as earth’s climate went through sudden and dramatic changes? | [
"reflex behaviors",
"mutations",
"body temperature",
"hair growth"
] | C | Mammals have the ability to regulate body temperature. This is an advantage, as Earth’s climate went through sudden and dramatic changes. Mastodons, saber tooth tigers, hoofed mammals, whales, primates and eventually humans all lived during the Cenozoic Era ( Figure below ). |
SciQ | SciQ-298 | sequence-alignment, k-mer, repeat-elements, sequence-homology
Title: Finding 2000 bp sequences that occur more than once in the genome I am looking for a software that can identify long sequences (1500-2000 bp) that occur more than once in my genome of interest. A k-mer counter like KMC could have worked, but KMC has a max limit of 256 bp. If I can club contiguous 256-mers from KMC, that would work too, but I don't know how to do that. Any ideas? MUMmer includes a repeat-match tool which can do exactly that:
$ repeat-match
USAGE: repeat-match [options] <genome-file>
Find all maximal exact matches in <genome-file>
Options:
-E Use exhaustive (slow) search to find matches
-f Forward strand only, don't use reverse complement
-n # Set minimum exact match length to #
-t Only output tandem repeats
-V # Set level of verbose (debugging) printing to #
Note that a "maximal exact match" is just a maximal repeat.
The following is multiple choice question (with options) to answer.
What is the term for very large arrays of tandemly repeating, non-coding dna? | [
"models dna",
"satellite dna",
"addition dna",
"recombinant dna"
] | B | The majority of the human genome is non-coding sequence. These sequences include regulatory sequences, and DNA with unknown functions. These sequences include tandem repeat elements known as satellite DNA , and transposons. Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. The repeating units can be just a single base (a mono nucleotide repeat), two bases (a dinucleotide repeat), three bases (a trinucleotide repeat) or a much larger repeating unit. Some repeating units are several thousand base pairs long, and the total size of a satellite DNA segment can be several megabases without interruption. |
SciQ | SciQ-299 | ocean, ocean-currents, sea-level, topography, bathymetry
Title: Does bathymetry affect ocean topography/height? Here is a map of ocean surface height or topography:
The following is multiple choice question (with options) to answer.
What kind of map can show the features of the bottom of a body of water? | [
"bathymetric",
"basic",
"country",
"topographic"
] | A | Oceanographers use bathymetric maps to show the features of the bottom of a body of water. |
SciQ | SciQ-300 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
What evolved, adapted response to resource availability is the long-range seasonal movement of animals? | [
"regulating",
"Stagnation",
"migration",
"changing"
] | C | Migration Migration is the long-range seasonal movement of animals. It is an evolved, adapted response to variation in resource availability, and it is a common phenomenon found in all major groups of animals. Birds fly south for the winter to get to warmer climates with sufficient food, and salmon migrate to their spawning grounds. The popular 2005 documentary March of the Penguins followed the 62-mile migration of emperor penguins through Antarctica to bring food back to their breeding site and to their young. Wildebeests (Figure 45.35) migrate over 1800 miles each year in search of new grasslands. |
SciQ | SciQ-301 | sensation, olfaction
http://www.comeaddestrareuncane.com/blog/tag/cani-molecolari/
In the dog, the surface of the olfactory mucosa varies between 70 and 150 cm2 - in this tissue the number of olfactory receptors varies from 250 to 280 million - In 1962, Becker et al. showed that dogs are able to recognize substances in dilutions from 1/100 to 1/10.000.000.
- http://milano.corriere.it/milano/notizie/cronaca/12_febbraio_19/cani-olfatto-parere-esperto-1903358352720.shtml
Have you noticed how a dog sniffs the urine of a female "tasting it"? It is the same action that makes the viper when it follows the track of the mouse: it evertes the tongue and carries on it the odorous particles in the buccal cavity, and this organ has a function in the middle between the olfactory and gustatory ones. "Pointing dogs" is as pointing "the wild" taste the smell.
"Eat the scent", in the jargon, because savored, not only in terms of smell, the smell of the wild. The Jacobson's organ is then a second organ capable of perceiving odors, the first we've said is represented ciliated epithelium of the mucous membrane of the nose.
But there is a third organ called the "Rodolfo-Masera" which also serves to sense the emanations chemical (not yet known which), that way you could explain a specialization of these organs to perceive certain groups of biochemicals than others.
- http://www.laciotola.net/Cani/la-funzione-olfattiva-del-cane.html
The following is multiple choice question (with options) to answer.
When animals get rid of their gaseous waste, what is exhaled through their mouth and nose? | [
"carbon dioxide",
"oxygen",
"hydrogen",
"carbon monoxide"
] | A | |
SciQ | SciQ-302 | volcanology, paleontology, volcanic-hazard, archaeology, pyroclastic-flows
Title: Are Pompeii and Herculaneum unique? Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human – have been entombed in the volcanic ash, with the possibility of revealing their forms by producing casts from the voids? Such sites, if they exist, could reveal exciting new knowledge about ancient peoples and animals. Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.
The following is multiple choice question (with options) to answer.
What is another name for composite volcanos? | [
"stratovolcanoes",
"fjords",
"seismic giants",
"fault lines"
] | A | Composite volcanoes are also called stratovolcanoes. This is because they are formed by alternating layers (strata) of magma and ash ( Figure below ). The magma that creates composite volcanoes tends to be thick. The steep sides form because the lava cannot flow too far from the vent. The thick magma may also create explosive eruptions. Ash and pyroclasts erupt into the air. Much of this material falls back down near the vent. This creates the steep sides of stratovolcanoes. The composition of magma that erupts at composite volcanoes is usually felsic (rhyolite) or intermediate (andesite). |
SciQ | SciQ-303 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
Fossil records support the idea that periods of little change may be interrupted by bursts of rapid change, an evolutionary model contrasted by what? | [
"elitism",
"gradualism",
"darwinian",
"minimalism"
] | B | When geologic and climatic conditions are changing, evolution may occur more quickly. Thus, long periods of little change may be interrupted by bursts of rapid change. This model of the timing of evolution is called punctuated equilibrium . It is better supported by the fossil record than is gradualism. |
SciQ | SciQ-304 | meteorology, atmosphere, wind, air-currents
Title: Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.
What forces would cause such a mass movement of air? Wind is caused by pressure differences. Think of a balloon full of air; poke a hole in it and the air comes out. Why? Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.
There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role. The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:
$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$
In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.
The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel). The RHS represent a number of factors that produce a change in the wind. From left to right:
Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)
The following is multiple choice question (with options) to answer.
What type of winds occur when air is forced over a mountain range? | [
"chinook winds",
"doldrums",
"local winds",
"trade winds"
] | A | Chinook winds ( Figure below ) occur when air is forced over a mountain range. Warm air rises over the Sierra Nevada in California, for example, because it is pushed eastward by the westerly winds. The air cools as it rises and precipitates. The air is now dry. It sinks down the far side of the mountains and may create strong winds. These Chinook winds are relatively warm. If there is snow, the winds may melt it quickly. The dry sinking air creates a rainshadow effect . Rainshadow effect is responsible for many of the world's deserts. |
SciQ | SciQ-305 | visible-light, sun, weather
Title: Why are clouds lighter than the sky during the day but darker at night This is probably a very basic question but I couldn't find a good answer to it, most search results are about rain clouds or clouds appearing red at night (something I've never seen except for during sunset but apparently it's common in bigger cities).
Basically what I'm wondering is why clouds during the day appear lighter than the sky (white vs light blue) while clouds at night and during the evening appear darker than the sky (see image).
Image quality is low because I took it with my phone through my window.
I guess the clouds could be blocking the light and therefore appear darker but in that case, shouldn't the same thing be happening during the day? There could be quite a few things going on.
Off the bat there's no incoming light for them to scatter: during the day, clouds are white because the water droplets are big enough for all visible light to cause Mie scattering, but if you don't have much light falling on them, you can't observe the scattering and you can't observe light passing through either.
Then you could consider the fact that in some places, it rains more in the evening/night than during the day (if you have hotter surface temperatures during the afternoon, you see cloud formation and precipitation during the late evening, and with the lower temperatures in the night, the air is more likely to become saturated, see Dew Point), and clouds which precede rain are thicker and denser. They don't allow much light pass through.
And lastly, there's less ambient light which they can reflect back towards you.
The following is multiple choice question (with options) to answer.
What do clouds trap into the atmosphere at night? | [
"heat",
"light",
"smog",
"seawater"
] | A | Clouds block sunlight in the day. Clouds trap heat in the atmosphere at night. |
SciQ | SciQ-306 | neuroscience, neurophysiology, neurotransmitter
Title: Correlation between morphology of neurons and neurotransmitters Are there known significant (positive or negative) statistical correlations between the morphology type of neurons and the neurotransmitters that they use (presynaptic, i.e. transmitters that are released, and postsynaptic, i.e. transmitters that are received)?
This question assumes, that a definite set of morphology types has been defined. The answer depends on this definition, of course. Yes, at least for the neurotransmitters that a given cell releases.
As far as the neurotransmitters a cell responds to, you are really better off thinking in terms of receptor expression. Most neurons will express receptors for many different neurotransmitters. It's far too broad to go into them all in an answer here.
As far as the transmitters that cells release, morphological types of neurons are very often associated with release of particular neurotransmitters. In the cortex, for example, pyramidal cells principally release glutamate while there are potentially dozens of morphological types (again, depending on how you define them) that release GABA; in the cerebellum, Purkinje neurons release GABA whereas granule cells release glutamate.
However, be careful: some terms like "granule cell" don't really refer to a special morphological type. They are really just describing "small cells in close proximity": these can be completely different types in different brain regions. It really makes no sense to ask these types of questions for the brain as a whole, you have to study individual brain regions, each of which is organized quite differently from the others.
The following is multiple choice question (with options) to answer.
A nerve cell that carries messages is called a? | [
"neuron",
"platelet",
"stem cell",
"mitochondria"
] | A | The nervous system is made up of nerves. A nerve is a bundle of nerve cells. A nerve cell that carries messages is called a neuron. The messages carried by neurons are called nerve impulses. |
SciQ | SciQ-307 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
What group of animals are the largest arthropods? | [
"spiders",
"birds",
"fish",
"insects"
] | D | There are several traits shared by all arthropods. Arthropods have a complete digestive system. They also have a circulatory system and a nervous system. In addition, they have special organs for breathing and excreting wastes. Other traits of arthropods include:. |
SciQ | SciQ-308 | cell-biology, cancer, cloning
Title: Difference between clonal and subclonal mutations I'm a physicist writing a proposal that has to do with cancer as a disease driven by evolutionary selection. As far as I understand, all tumors start with a single precursor (single cell or group of cells), and the other cells derive from this precursor by cycles of alterations and selection processes.
Reading recent articles, such as this, I learned that the derived cells include both clones and subclones. Since I'm not sure I understood things correctly, I have a few questions on the difference between the two words:
Is it OK to call clones the cells derived from the precursors?
When should I use subclones?
In the case of heterogeneity, is it fine to call clonal population a group of clones with the same characteristics? clones means when a cell has the same DNA characteristics as his predecessor so in that case of yours you could say that those cells are clones while for sub-clones I am not that sure, the difference of clone and sub-clone is that a sub-clone is basically a clone who is then remade with a different characteristic(an upgrade if you will) , since cancer are mutated cells you could call them like that but only if you study its DNA, meaning you have to study deep to find out if there are sub-clones in there. AS for the 3 question I didn't quite understood what you meant cuz you just used 2 words with opposite meaning because heterogeneity means a group of organismes with different characteristics and clonal population means organismes with same DNA ( much like a colony of bacteria).
The following is multiple choice question (with options) to answer.
What term describes a collection of similar cells that had a common embryonic origin? | [
"organ-level organization",
"plasma",
"tissue",
"nucleus"
] | C | Complex Tissue Structure A hallmark trait of animals is specialized structures that are differentiated to perform unique functions. As multicellular organisms, most animals develop specialized cells that group together into tissues with specialized functions. A tissue is a collection of similar cells that had a common embryonic origin. There are four main types of animal tissues: nervous, muscle, connective, and epithelial. Nervous tissue contains neurons, or nerve cells, which transmit nerve impulses. Muscle tissue contracts to cause all types of body movement from locomotion of the organism to movements within the body itself. Animals also have specialized connective tissues that provide many functions, including transport and structural support. Examples of connective tissues include blood and bone. Connective tissue is comprised of cells separated by extracellular material made of organic and inorganic materials, such as the protein and mineral deposits of bone. Epithelial tissue covers the internal and external surfaces of organs inside the animal body and the external surface of the body of the organism. |
SciQ | SciQ-309 | biochemistry, molecules, polymers, chemical-biology
A monomer is the simplest building block of a macromolecule with the properties of that macromolecule. They can be strung together to produce a macromolecule (usually by dehydration synthesis).
I would have no problem with these definitions if not for my teacher mentioning once that some monomers can also be macromolecules by themselves. Because some monomers of certain macromolecules- such as the monosaccharide glucose vs. the disaccharide sucrose or the polysaccharide amylose - can act on their own as an essential and functional carbohydrate, they are macromolecules by themselves.
Is this true? For example, could glucose be a macromolecule by itself?
Thanks. I can't think of an example where a biological monomer would be a macromolecule.
Definitions of macromolecule vary, usually by molecular weight or number of monomers (repeat units).
Personally, I'd go with ~1000 Dalton for a minimum, but the original definition of 1000 atoms is a good start too.
In any case, no biological monomer, including glucose will function the same as a macromolecule.
Consider starch - a macromolecule of sugars. It doesn't dissolve as quickly as simple sugar and has different physical properties.
Update
To clarify my comments.. Macromolecules or polymers are made up of monomers the way words are made up of letters. So no, a glucose molecule isn't really the same as a macromolecule, just like "R" is not a word.
Yes, macromolecules can be used to make larger assemblies like microtubules, filaments, etc., much the same way that words can form sentences and paragraphs.
In the polymer literature there's even the concept of a "macromonomer" referring to a monomer that is already large in size.
In my opinion though, the basic constituents (monomers) are still amino acids, nucleic acids, sugars, etc. These are not macromolecules.
The following is multiple choice question (with options) to answer.
Most biochemical molecules are macromolecules, meaning that they are what? | [
"very large",
"very abundant",
"very small",
"very dense"
] | A | Most biochemical molecules are macromolecules, meaning that they are very large. Some contain thousands of monomer molecules. |
SciQ | SciQ-310 | neuroscience, neuroanatomy
Likewise, the spinal chord is structured into sensory and motor regions. In summary, the spinal chord consists of: 1) cell bodies (motor, sensory, inter; grey in the picture), 2) ascending axons (blue), 3) descending axons (red). Similar to nerves, axons going up or down the spinal chord are bundled into "tracts". Sensory axons are never bundled with motor axons, making it possible to create a map of the spinal chord in cross-section.
The tracts' names might be a bit confusing at first, but on second look are actually pretty self-explanatory. They usually contain where the axons come from and where they are going in order to synapse with other neurons. E.g. the spinocerebellar tract is formed of axons coming from the spine and going to the cerebellum. Given that the cerebellum is near the brain and the spine is further down, this is obviously an ascending tract - and ascending tracts are always sensory (because sensory information never needs to be carried downwards due to the brain being at the top).
Where it gets blurry
The sensory/motor separation isn't always as clear as I've described above. In fact, nerves (bundles of axons anywhere in the body outside of the CNS) will usually contain both sensory and motor pipelines. In particular, the cranial nerves (12 of the most important nerves) all include sensory and motor components for the respective part of the body that they manage. E.g. the facial nerve contains both the sensory connections for parts of the tongue and the motor connections that control facial muscles.
Another more complex example is pain sensation, where interneurons in the spinal chord can feed back onto sensory neurons and inhibit their signals, or axons can inhibit those packed in the same nerve bundle simply due to electrical effects.
The following is multiple choice question (with options) to answer.
The name of a spinal cord region corresponds to the level at which spinal nerves pass through the what? | [
"notochord",
"intervertebral foramina",
"synovial fluid",
"lumbar foramina"
] | B | The Spinal Cord The description of the CNS is concentrated on the structures of the brain, but the spinal cord is another major organ of the system. Whereas the brain develops out of expansions of the neural tube into primary and then secondary vesicles, the spinal cord maintains the tube structure and is only specialized into certain regions. As the spinal cord continues to develop in the newborn, anatomical features mark its surface. The anterior midline is marked by the anterior median fissure, and the posterior midline is marked by the posterior median sulcus. Axons enter the posterior side through the dorsal (posterior) nerve root, which marks the posterolateral sulcus on either side. The axons emerging from the anterior side do so through the ventral (anterior) nerve root. Note that it is common to see the terms dorsal (dorsal = “back”) and ventral (ventral = “belly”) used interchangeably with posterior and anterior, particularly in reference to nerves and the structures of the spinal cord. You should learn to be comfortable with both. On the whole, the posterior regions are responsible for sensory functions and the anterior regions are associated with motor functions. This comes from the initial development of the spinal cord, which is divided into the basal plate and the alar plate. The basal plate is closest to the ventral midline of the neural tube, which will become the anterior face of the spinal cord and gives rise to motor neurons. The alar plate is on the dorsal side of the neural tube and gives rise to neurons that will receive sensory input from the periphery. The length of the spinal cord is divided into regions that correspond to the regions of the vertebral column. The name of a spinal cord region corresponds to the level at which spinal nerves pass through the intervertebral foramina. Immediately adjacent to the brain stem is the cervical region, followed by the thoracic, then the lumbar, and finally the sacral region. The spinal cord is not the full length of the vertebral column because the spinal cord does not grow significantly longer after the first or second year, but the skeleton continues to grow. The nerves that emerge from the spinal cord pass through the intervertebral formina at the respective levels. As the vertebral column grows, these nerves grow with it and result in a long bundle of nerves that resembles a horse’s tail and is named the cauda equina. The sacral spinal cord is at the level of the upper lumbar vertebral bones. The spinal nerves extend from their various levels to the proper level of the vertebral column. |
SciQ | SciQ-311 | h. Evaluate C.
i. Compute Q(7), the amount of glucose produced during the day.
Exercise 10.3.5 “Based on studies using isolated animal pancreas preparations
maintained in vitro, it has been determined that insulin is secreted in a biphasic manner in response to a marked increase in blood glucose. There is an initial burst of insulin secretion that may last 5-15 minutes, a result of secretion of preformed insulin secretory granules. This is followed by more gradual and sustained insulin secretion that results largely from biosynthesis of new insulin molecules. ” (Rhoades and Tanner, P 710)
a. A student eats a candy bar at 10:20 am. Draw a graph representative of the rate of insulin secretion between 10:00 and 11:00 am.
b. Draw a graph representative of the amount of serum insulin between 10:00 and 11:00. Assume that insulin is degraded throughout 10 to 11 am at a rate equal to insulin production before the candy is eaten, and that serum insulin at 10:00 was Iq.
CHAPTER 10. THE FUNDAMENTAL THEOREM OF CALCULUS
468
c. Write an expression for the amount of serum insulin, I(t), for t between 10:00 and 11:00 am.
Exercise 10.3.6 Equal quantities of gaseous hydrogen and iodine are mixed resulting in the reaction
which runs until I 2 is exhausted [H 2 is also exhausted). The rate at which I 2 disappears is ^°’^ 2 gm/sec. How much I 2 was initially introduced into the mixture?
a. Sketch the graph of the reaction rate, r(t) = jp^yi-
b. Approximately how much I 2 combined with H 2 during the first second?
c. Approximately how much I 2 combined with H 2 during the second second?
d. Let Q(x) be the amount of I 2 that combines with H 2 during time 0 to 2; seconds. Write an integral that is Q(x).
e. What is Q\x)l
f. Compute W'{x) for W(x) = =^.
g. Show that there is a number, C, for which Q(x) = W(x) + C.
h. Show that C = 0.2 so that Q(x) = 0.2 – g.
The following is multiple choice question (with options) to answer.
Tests for levels of what in blood allow a diabetic patient to regulate how much insulin to administer? | [
"glucose",
"chloride",
"protein",
"alcohol"
] | A | Laboratory testing has come to the local drug store or grocery store because of developments in chemistry. You can test your blood glucose using a simple portable device that runs a chemical test on the blood sample and tells you how much glucose is present, allowing a diabetic patient to regulate how much insulin to administer (chemistry is also used to produce the insulin and the disposable syringe that administers the drug). |
SciQ | SciQ-312 | nitrogen
Step three is when plants and the animals that live of the plants die and breaks down into ammonia and other waste products (this is where many explanations of the nitrogen cycle usually starts). The waste products gets converted into ammonia by bacteria and the ammonia gets converted to nitrite and the entire cycle starts all over again.
Legumes have a symbiotic relationship with some bacteria that can fixate nitrogen (N2) https://aces.nmsu.edu/pubs/_a/A129/
sources:
https://science.howstuffworks.com/life/biology-fields/nitrogen-cycle.htm
https://www.britannica.com/science/denitrifying-bacteria
The rest is from my memory.
The following is multiple choice question (with options) to answer.
The process of breaking down food into nutrients is known as __________ | [
"filtration",
"absorption",
"digestion",
"energy"
] | C | As food is pushed through the GI tract by peristalsis, it undergoes digestion. Digestion is the process of breaking down food into nutrients. There are two types of digestion: mechanical digestion and chemical digestion. |
SciQ | SciQ-313 | Moreover, if you want to know about the logic in general terms this article could be useful.
Logic, originally meaning "the word" or "what is spoken", but coming to mean "thought" or "reason", is a subject concerned with the most general laws of truth, and is now generally held to consist of the systematic study of the form of valid inference. A valid inference is one where there is a specific relation of logical support between the assumptions of the inference and its conclusion.
• Hmm, I'm not sure if this is very helpful here. Would you say that David's post makes yours 'superseded'? If not, why? Try to expand on that. – Discrete lizard Mar 25 '18 at 14:03
• @OmG : Can you recommend a list of materials to learn from ? – Sheldon Kripke Mar 31 '18 at 3:54
The following is multiple choice question (with options) to answer.
Reasoning can be broken down into two categories: deduction and? | [
"conduction",
"invention",
"induction",
"preduction"
] | C | Any useful hypothesis will allow predictions based on reasoning. Reasoning can be broken down into two categories: deduction and induction. Most reasoning in science is formed through induction. |
SciQ | SciQ-314 | python, numpy, simulation, physics, matplotlib
def plot(ship,planets):
"""3d plots earth/moon/ship interaction"""
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D
# Initilize plot
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')
ax.set_xlabel('X Km')
ax.set_ylabel('Y Km')
ax.set_zlabel('Z Km')
ax.set_xlim3d(-500000, 500000)
ax.set_ylim3d(-500000, 500000)
ax.set_zlim3d(-500000, 500000)
ax.plot(xs=ship.hist[0][0::10],
ys=ship.hist[1][0::10],
zs=ship.hist[2][0::10],
zdir='z', label='ys=0, zdir=z')
# Plot planet trajectory
for planet in planets:
ax.plot(xs=moon.hist[0],
ys=moon.hist[1],
zs=moon.hist[2],
zdir='z', label='ys=0, zdir=z')
# Plot Earth (plot is moon position relative to earth)
# also plotting to scale
(xs, ys, zs) = drawSphere(0, 0, 0, 6367.4447)
ax.plot_wireframe(xs, ys, zs, color="r")
plt.show()
def sim(startTime, endTime, step, ship, planets):
"""Runs orbital simulation given ship and planet objects as well as start/stop times"""
# Caculate moon planet update rate (1/10th as often as the craft)
plan_step = int(math.ceil(((endTime - startTime) / step)/100))
# Initilize positions of planets
for planet in planets:
planet.getRelPos(startTime)
planet.log()
The following is multiple choice question (with options) to answer.
What are used to make maps of the moon and other planets? | [
"topographical charts",
"imaging satellites",
"rendering satellites",
"radio telescopes"
] | B | Astronomers use imaging satellites to study and make maps of the Moon and other planets. |
SciQ | SciQ-315 | statistical-mechanics, partition-function
where $S_D(R)$ is the surface area of the hypersphere.
Fun fact: if we are dealing with non-interacting particles, i.e.
$$H=\sum_i^N \frac{p_i^2}{2m}$$
we have
$$\int_{E<\sum p_i^2/2m<E+E_0} d^{3N}p \ d^{3N}q = V^N \int_{E<\sum p_i^2/2m<E+E_0} d^{3N}p $$
and this integral is exactly an hyperspherical shell.
References: M. E. Tuckerman, Statistical Mechanics: Theory and Molecular Simulation
The following is multiple choice question (with options) to answer.
What term describes how closely packed the particles of matter are? | [
"range",
"mass",
"density",
"space"
] | C | Density is an important physical property of matter. It reflects how closely packed the particles of matter are. When particles are packed together more tightly, matter has greater density. Differences in density of matter explain many phenomena, not just why helium balloons rise. For example, differences in density of cool and warm ocean water explain why currents such as the Gulf Stream flow through the oceans. You can see a colorful demonstration of substances with different densities at this URL:. |
SciQ | SciQ-316 | population-dynamics, population-biology
Title: Spread of a benign virus in a population over time This is a somewhat difficult (for me) population dynamics question and I wonder if someone with experience in this area could suggest a reasonable approach?
My simplifying assumptions: As a gross oversimplification, let p(k) be the world's population at generation k, and assume a smooth exponential curve that models p(k) from $k=0$ at 10,0000 B.C.E to generation $k=600$ in 2000 C.E. A generation is 20 years, and in acc. with this Wiki there are about 4 million individuals at $k=0$ and 6070 million at $k=600.$
(Of course the exponential model is bad, as world population growth appears to have been sluggish before recorded history.)
Now assume a benign virus infects 120 individuals in $k=0.$ It benignly infects all individuals who have at least one infected parent. Perhaps unimportantly, it also continues to infect 30 new individuals per million in each generation (because its found in the soil), but would not infect those already exposed.
Call infected individuals II and non-infected NI. They are indistinguishable without clinical tests--which are not done, since the virus is harmless. Since II individuals are almost certain to mate with NI individuals, in earlier generations, the number of II will grow very quickly. For a time the growth rate of II will exceed that of p(k). At some point it will be unlikely that an II individual will encounter an NI mate, however a few NI persons will still pair with NI mates--for a while.
My question is, after 600 generations, what is a reasonable estimate of the percentage of II in the population? Is is possible that there would be any NI individuals left? Or would we have some sort of dynamic equilibrium between II and NI in which (I think) the former would strongly dominate?
FWIW, the population growth model is $p(k)=4e^{0.012 k}$ with $p(k)$ in millions. For simplicity, I denote the population of non-infected individuals by $N$ and the infected ones by $I$.
Model without soil infection
The following is multiple choice question (with options) to answer.
Populations of viruses do not grow through cell division because they? | [
"non living",
"Acidic",
"Static",
"are not cells"
] | D | Populations of viruses do not grow through cell division because they are not cells. Instead, they use the machinery and metabolism of a host cell to produce new copies of themselves. After infecting a host cell, a virion uses the cell’s ribosomes, enzymes, ATP, and other components to replicate. Viruses vary in how they do this. For example:. |
SciQ | SciQ-317 | parasitology
Title: Tapeworms and their effect on humans I've read that some people in some countries actually use tapeworms as a form of losing weight. What are the dangers to these people? I haven't really found much on this topic (besides popular sites) but I can summarize it here:
There are quite some tapeworms (or cestoda), I found numbers of up to 3500 species. They attach to the intestinal wall of the humans and then start to take up predigested food through their skin. With that, they reduce food from their host and start to grow, some get as long as 15 meters!
Some of the worms seem to be relatively harmless (besides stealing food), but this is more true for the first world. In poor countries, where there is not enough food, tapeworms can cause severe malnutrition.
Some tapeworms can migrate into the blood stream and from there into other tissues or organs like muscles, eye and brain. There they can cause cysts which can lead to organ failure and death.
For more information see this CDC webpage and this article: "Biochemistry and physiology of tapeworms.". This popular article is probably also interesting.
The following is multiple choice question (with options) to answer.
What is likely to happen to a parasite if it kills its host? | [
"it thrives",
"it adapts",
"it mutates",
"it dies"
] | D | Some parasites kill their host, but most do not. It’s easy to see why. If a parasite kills its host, the parasite is also likely to die. Instead, parasites usually cause relatively minor damage to their host. |
SciQ | SciQ-318 | crystal-structure
Title: Simple/ Primitive Tetragonal Bravais Lattice Are there any elements which exhibit the Simple(Primitive) Tetragonal Bravais Lattice? Chances are there are no such elements. This link seems to suggest so, but I wouldn't put too much trust in it. (To begin with, it claims only one crystal structure for each element, ignoring any polymorphs.) So what? This is not a fact of any consequence. It is about as (un)important as the knowledge that only one of the element names in English starts with "K", and none start with "J". Besides, both may change over time. New high-pressure crystal modifications of elements are discovered every now and then, and will be for a while, because no matter how far you reach, there is always a higher pressure.
Come to think of it, there are millions of different crystal structures out there. Elemental compounds are just a very tiny minority. Surely there are examples of all Bravais lattices (not that it matters much).
So it goes.
The following is multiple choice question (with options) to answer.
What is a type of solid that lacks an ordered internal structure? | [
"an elastic solid",
"ice",
"a sponge",
"an amorphous solid"
] | D | An amorphous solid is a solid that lacks an ordered internal structure. |
SciQ | SciQ-319 | experimental-physics
Title: Examples of a measurement slowly converging on the correct result after an initial eronious experiment? I remember hearing of cases where some initial measurement of a constant gives a value that is wildly inaccurate (either too high or too low). Subsequent experimental measurements, instead of disregarding the first and giving something close to the correct answer, tend to be within the margin of error of the first experiment but (somewhat) closer to the correct result. This process repeats itself until finally after many years the correct result is obtained.
The problem is I can't find any examples of this actually occurring. Is this one of those thing that people say as lore but are not actually true?
I thought that I heard of it happening with measurement of the speed of light, but looking back at the history it doesn't look like this happened with the historical data I can find. Several examples are given in Jeng's "A selected history of expectation bias in physics". The example you may have heard about, which became particularly well known after Richard Feynman remarked upon it, is Millikan's measurement of elementary charge.
The following is multiple choice question (with options) to answer.
What is it called when you get the same result after repeating an experiment? | [
"control",
"variable",
"initiation",
"replication"
] | D | Getting the same result when an experiment is repeated is called replication. If research results can be replicated, it means they are more likely to be correct. |
SciQ | SciQ-320 | organs, lifespan
Title: Organs lifespan out of the body What organ can be conserved outside of the body for the longest time and still function when reimplanted? Depends what you consider an organ. Typically though it's the cells which require the most metabolic activity which have the shortest life span. The kidney is the most of the major internal organs with up to 36 hours with liver coming second at up to 16 hours.
The following is multiple choice question (with options) to answer.
What is the largest human organ? | [
"skin",
"brain",
"lungs",
"stomach"
] | A | human body system that includes the skin, nails, and hair. |
SciQ | SciQ-321 | human-anatomy, cardiology
Title: Structure separating the left atrium from the ascending aorta? With reference to the (adult) anatomy of the human heart:
The left atrium (LA) and the proximal part of the ascending aorta (Ao) abut one another, as shown nicely in this image [1]. Is there a name for the wall(s) separating the LA and Ao? And is this a single structure (i.e. septum), or is there a sinus?
[1] http://www.radiologyassistant.nl/data/bin/w440/a5097978b829cd_3-chamber.jpg There isn't any particular structure there: you have the wall of the aorta/adventitia, and if you have an explanted heart there is a space and then the auricle of the left atrium on one side and the right atrium on the other. These would all be contained within the pericardium.
Where the aorta is most "touching" the left atrium is where the pulmonary veins come in: I think this picture from Gray is most helpful.
Figure 494. Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
There really isn't much to distinguish these veins from the non-auricle part of the atrium, similar to the vena cava on the right side. If you were to cut along the veins eventually you would just open up into the atrium.
The Visible Heart Lab is another good reference http://www.vhlab.umn.edu/atlas/aorta for cardiac anatomy.
The following is multiple choice question (with options) to answer.
In the chest, the trachea divides as it enters the lungs to form the right and left what? | [
"atrium",
"alveoli",
"ventricle",
"bronchi"
] | D | In the chest, the trachea divides as it enters the lungs to form the right and left bronchi . The bronchi contain cartilage, which prevents them from collapsing. Mucus in the bronchi traps any remaining particles in air. Tiny, hair-like structures called cilia line the bronchi and sweep the particles and mucus toward the throat so they can be expelled from the body. |
SciQ | SciQ-322 | elements
Title: What is the reason behind the characteristic colours of elements? I've been trying to find out about this for some time now and when I searched online, I couldn't get any proper reasons.
My question is: What is the reason for the characteristic colours of elements? For eg: Why does Sodium have a characteristic colour of silvery-white?
Is there any solid scientific reason behind this? Colour is a property of the light reflected or transmitted by any substance. Depending on the substance's characteristics (energy levels of constituent levels, bonding, intermolecular forces), there are certain available energy levels (molecular orbitals, bands etc) for the electrons. Whenever any wide spectrum energy is available to a compound (considering only the visible spectrum), then depending on the various energy gaps between the available to the electrons, different wavelengths will be selectively absorbed and re-emitted, but now in any random direction, therefore the reflected and the transmitted light will be partially deficient n these wavelengths. The absorption and re-emission is very characteristic of all substances, and hence, the wavelengths absorbed and the resultant spectrum (transmitted or reflected) will be characteristic. Depending on this spectrum, various colours can be seen for different compounds.
Sometimes, the energy gap between the electron energy level is very high and therefore the light in the visible spectrum cannot excite the electron. No wavelength will be absorbed and it will act as a transparent glass. If say, the gap corresponds to a energy gap of $E=h(4000A)$, then the blue light will be absorbed and the remaining light will be white-blue=yellow. This is the general way in which colors are produced. The energy gaps can be anything, the band gaps in metals, molecular orbital energy difference in covalent compounds, orbital energy difference in isolated elements, or simply the energy difference between the various vibrational modes in a gas/solid.
The following is multiple choice question (with options) to answer.
Many objects have color because they contain what? | [
"pigments",
"vitamins",
"salts",
"solvents"
] | A | Many objects have color because they contain pigments. A pigment is a substance that colors materials by reflecting light of certain wavelengths and absorbing light of other wavelengths. A very common pigment is the dark green pigment called chlorophyll, which is found in plants. Chlorophyll absorbs all but green wavelengths of visible light. Pigments are also found in many manufactured products. They are used to color paints, inks, and dyes. Just three pigments, called primary pigments, can be combined to produce all other colors. The primary colors of pigments are the same as the secondary colors of light: cyan, magenta, and yellow. |
SciQ | SciQ-323 | neurophysiology
Title: Why myelin sheat does not cover the whole axon? Is there an optimal lenght for myelin sheats to be effective and lead potential across the nerve cell? This has always bugged me. The nodes of Ranvier (the gaps between myelin sheath segments) speed up the action potential because the electric current can jump from node to node (or gap to gap). If the myelin covered the entire axon, the signal wouldn't have the gaps to speed up the signal. As for optimal length, the gap is 1μm long, but can be longer, on the order of millimeters depending on the type of cell. The length of the myelin doesn't matter so much as the length of the nodes of Ranvier because they are where the Na+/K+ channels are found so the ion exchange can occur. This is how an action potetial can occur, so the myelin not covering the entire axon is crucial for the ability of neurons to propagate a signal.
The following is multiple choice question (with options) to answer.
What is the process of action potentials in myelinated axons jumping between the nodes of ranvier called? | [
"saltatory conduction",
"saltatory movement",
"photoreactive conduction",
"pinworm conduction"
] | A | |
SciQ | SciQ-324 | natural-satellites, crater, hyperion
Title: What caused these strange craters on Hyperion? I was looking at pictures of the moons of Saturn and noticed that the craters on Hyperion have a strange shape, somewhat resembling sinkholes. They look a lot deeper than the impact craters on other moons (including ours). Is it an optical illusion (perhaps caused by the presence of dark material at the bottom of the craters?) that somehow makes them look deeper? If not, what process caused these holes to appear? According to Thomas et al. (2007), these craters are not unusually deep:
It is unlikely that unusual crater depths significantly enhance the sponge-like appearance. Crater depth-to-diameter ratios for the 13 examples that can be measured reliably using shadow lengths average 0.21 ± 0.05 (s.d.). These ratios are similar to values for fresh lunar craters, and are slightly greater than for some small rocky objects. They are slightly larger than that for craters on large icy satellites, 0.14.
What is unusual and gives a "sponge-like" appearance to Hyperion is the high density of craters and lack of intercrater plains:
For craters with diameters between 2 km and 11 km, Hyperion has a cumulative number of craters per unit area twice that on Phoebe; at similar resolution these objects are strikingly different.
To explain this, they proposed that ballistic ejecta from impact events, which usually cover older craters, are lost to space instead.
A more recent study (Howard et al., 2012) suggested that mass wasting processes (landslides) and CO$_2$ sublimation also account for this special morphology, especially for the dark-floored craters. This has been confirmed by Dalton et al. (2012), who called these craters "suncups":
The irregular shapes of the sublimation pits (suncups) support the
hypothesis of extensive mass wasting and sublimation degradation
(Moore et al., 1996, Howard et al., 2011, Howard et al., 2012) largely
associated with the loss of volatiles (including water ice). When the
ices evaporate, entrained low-albedo grains accumulate in lag
deposits, which are subject to solar heating. Warm grains accelerate
both the local evaporation of ices and their own spatial
concentration.
The following is multiple choice question (with options) to answer.
What do craters and rifts become when the fill with water? | [
"rivers",
"lakes",
"creeks",
"grasses"
] | B | Craters and rifts become lakes when they fill with water. Where does the water come from?. |
SciQ | SciQ-325 | thermodynamics, electricity
Title: Removal of heat from a closed system using electricity I was thinking this morning about how heat could be removed from a system in such a way that it is stored for future use. My ideas are a form of thermo-electric system that converts heat into electricity which can be stored in batteries and capacitors. My question is, is it possible to use electricity as a medium to remove heat from a system? Using or generating the electricity is irrelevant, as long as more heat isn't generated. My goal is to remove heat without generating more heat. The closest existing solution to what you're looking for is probably Peltier cooling.
Of course Peltier coolers don't break the Second Law of Thermodynamics either: they are heat pumps, with a cold sink and a hot sink.
The following is multiple choice question (with options) to answer.
What kind of power does not produce any pollutants, but produces waste that can be difficult to dispose of? | [
"solar",
"electrical",
"nuclear",
"biofuel"
] | C | Nuclear power is a controversial subject in California and most other places. Nuclear power has no pollutants including no carbon emissions. However, power plants are not always safe. The long-term disposal of wastes is a problem that has not yet been solved. The future of nuclear power is murky. Find out more at: http://science. kqed. org/quest/audio/new-nuclear/. |
SciQ | SciQ-326 | human-physiology, digestion, stomach
The stomach accomplishes much of its function by mechanically breaking down the swallowed food particles and mixing them with acid and enzymes into a sort of slurry. To do this, there are three major layers of muscle surround the stomach - from the outside, the longitudinal layer, the circular layer, and the oblique layer. The stomach also has two holes in it - the gastroesophageal opening, coming from the esophagus with the swallowed food/saliva mix, and the pylorus, where the food/acid/enzyme slurry exits into the duodenum, which is the beginning of the small intestine.
Due to the three layers of (rather strong) muscle, the stomach doesn't have a lot of expansion capability once it is filled completely to capacity. Fortunately, this almost never occurs (despite how we may feel after a large meal) because material is always leaving the stomach on its way to enzymatic digestion in the intestines. Additionally, once the stomach is filled to a certain extent, hormones such as leptin are secreted that give you the feeling of being sated, or full, triggering the brain to make you stop eating.
Of course, as we can see with the current epidemic of obesity around the world, the stomach can change its size over time. However, this is a rather slow process (weeks to months to years) of adapting to continuously consuming large meals.
But what would happen if you completely ignored these internal warnings, or were being force-fed, or whatever? Instead of rupturing (the biological equivalent of "exploding"), food would most likely be expelled either into the small intestine or back into the esophagus and back up the way it came down, i.e. causing vomiting.
The following is multiple choice question (with options) to answer.
What is the long, narrow tube that carries food from the pharynx to the stomach by the mechanism of peristalsis? | [
"esophagus",
"gallbladder",
"liver",
"spinal cord"
] | A | The esophagus is a long, narrow tube that carries food from the pharynx to the stomach. It has no other purpose. Food moves through the esophagus because of peristalsis. At the lower end of the esophagus, a circular muscle, called a sphincter, controls the opening to the stomach. The sphincter relaxes to let food pass into the stomach. Then the sphincter contracts to prevent food from passing back into the esophagus. |
SciQ | SciQ-327 | thermodynamics
Title: Does a gas condenses above its dew point? We all know that at temperatures much below the boiling point, evaporation occurs and liquid/vapor equilibrium exists.
So if we have steam at temperature greater than dew point, does it undergoes condensation at that temperature? Let's, for simplicity, consider a closed container with a liquid. In such closed system, evaporation and condensation happen simultaneously.
The rate of evaporation increases with temperature. The rate of condensation, which happens when vapor molecules hit the surface of the liquid, depends on the vapor pressure.
At equilibrium, the rates of evaporation and condensation are the same and the temperature is a dew point, by definition.
If the temperature is raised above that point, the rate of evaporation will exceed the rate of condensation, but, the condensation will still occur. This will continue until the new equilibrium is achieved, with the new temperature becoming a new dew point.
So, for a closed system, condensation does happen at temperatures above the dew point.
In an open environment, when the vapor does not come in contact with liquid, the condensation, generally, should not occur above the dew point.
The following is multiple choice question (with options) to answer.
What is the temperature at which condensation of water vapor occurs called? | [
"the tipping point",
"the cooling point",
"the dew point",
"the boiling point"
] | C | The temperature at which condensation of water vapor occurs is called the dew point. The dew point varies depending on air temperature and moisture content. |
SciQ | SciQ-328 | physical-chemistry, bond, enthalpy, hydrogen
Olefins are less stable than their corresponding alkane analogues. For example, when ethene is hydrogenated to ethane roughly 33 kcal/mol of heat is given off because ethene has a higher energy content than ethane.
Why is this, why is a molecule with a double bond higher in energy than a molecule without a double bond?
There are two equivalent ways to describe the orbitals in ethene. One is the "double bond" description where a pi and sigma bond exist together side by side. We know that a pi bond is not as strong as a sigma bond due to poorer overlap with the pi bond compared to the the sigma bond. It only takes something on the order of 60 kcal/mol to break a pi bond and produce cis-trans isomerization about the double bond, whereas it takes something like 90 kcal/mol to break a carbon-carbon single bond. This poorer overlap with the pi bond causes ethene to be higher in energy than ethane. Alternatively one can view ethene as a two-membered ring, no pi bond, just 2 sigma bonds between the 2 carbons forming a two-membered ring. It is easy to see that such a ring system would contain a significant amount of strain.
Whether you use the pi bond or two-membered ring approach to describe olefinic double bonds, both lead to the conclusion that olefins are destabilized (higher in energy content) due to poor overlap or ring strain (which in itself is really a reflection of poor overlap). Because of this destabilization, alkenes will generally have lower activation energies and more heat will be given off when they react compared to alkanes.
Example:
Let's consider the bromination of ethene and ethane
$$\begin{align}
\ce{C2H4 + Br2 &-> BrH2C-CH2Br}\\
\ce{C2H6 + Br2 &-> 2 CH3Br}
\end{align}$$
The following is multiple choice question (with options) to answer.
Alkenes have double bonds while alkynes have what? | [
"quadruple bonds",
"single bonds",
"equal bonds",
"triple bonds"
] | D | Alkenes have double bonds; alkynes have triple bonds. Both undergo addition reactions. |
SciQ | SciQ-329 | inorganic-chemistry, everyday-chemistry, extraction
The main process for production of aluminum metal requires a current of 400 kiloamperes and temperatures of 950 C. In contrast, the main process for sodium metal production requires a current of 30 kiloamperes and temperatures of 600 C.
The main reason would be because sodium is too reactive to be used. The sodium metal would react with the water and form sodium hydroxide. This reaction would be too fast and violent that you wouldn't be able to recover copper.
So your teacher was right in pointing out that sodium is too reactive.
The following is multiple choice question (with options) to answer.
What is our main source of aluminum ore? | [
"tin",
"bauxite",
"cobalt",
"coal"
] | B | Weathering may concentrate some resources. In tropical climates, chemical weathering can be intense. Some minerals dissolve and water carries them away. This leaves behind the materials that are not soluble. Bauxite is aluminum oxide that collects this way. Bauxite is our main source of aluminum ore. |
SciQ | SciQ-330 | evolution, experimental-design, ecosystem
Title: What insect/invertebrate species evolves fastest? I am starting an experiment in which I will be forcing evolution in a moderately complex species of insect or invertebrate. I am prepared for the possible longevity of this experiment, but i have no clue what species i should use. I would prefer a species that can easily respond to biotic challengers. Reason being, every abiotic factor will be promoting the growth and prosperity of the target species, however every biotic factor will be trying to kill the target species. The species can be aquatic, amphibious or terrestrial. Drosophila melanogaster. (fruit-fly, pomice-fly)
Image, public domain, via Wikipedia 2022.
Development time is under ideal conditions 8.5 days (at 25 Celsius, 77 Fahrenheit), the females produce perhaps 500 eggs per generation which can hatch in 12-15 hours - from the point of view of turnover, you should be able to observe many generations in a short-ish period at one generation per ten days in reasonable conditions.
Their diet is fruit, fungi - both preferably decomposing and are able to be anaesthetised with ether or carbon dioxide.
They have acted as a model organism (eukaryote) for the study of genetics and there are many known mutations, and established ways to produce them (ethyl methane sulfonate, ionising radiation).
The following is multiple choice question (with options) to answer.
Rapidly produced genetic vairants are found in organisms with what type of generation time? | [
"oscillating",
"repeating",
"short",
"long"
] | C | |
SciQ | SciQ-331 | immunology, pathology
Title: Action of Ebola Viruses This video suggests that the first cell to be the victim of viral infection of ebola is the dendritic cell which acts as the leader of immune system cells.But I am unable to understand how the dendritic cells get infected if they are the leaders? Viruses can infect any cell:
a virus must have a host cell (bacteria, plant or animal) in which to live and make more viruses. Outside of a host cell, viruses cannot function.
Source
This includes the dendritic cells:
Dendritic cells are antigen-presenting cells of the immune system. Their main function is to process antigen material and present it on the cell surface to the T cells of the immune system. They act as messengers. They don't actually release any antibodies.
Source
Quite simply, at the beginning of an infection, the viruses / bacteria will be destroyed by macrophages.
The dendritic cell will "pick up" some of the leftover pieces.
When it finds a T-Cell that has the same configuration, it orders lots of identical T-Cells to be made. These T cells have multiple jobs, one of which is activating the B cells. It is the B cells that release the antibodies.
So Ebola.
If the dendritic cells are "invaded", then the only line of defence is the macrophages. This is often not enough to stop an attack, and it multiplies out of control.
The reason the Dendritic cells can be invaded is because they are just as vulnerable as other cells. They haven't activated the T cells, and they haven't activated the B cells, so there is nothing protecting them.
Images Source (YouTube video)
The following is multiple choice question (with options) to answer.
What are the 2 primary hosts of ebola in central africa? | [
"apes and bats",
"hyenas and apes",
"lions and elephants",
"apes and hippos"
] | A | Several lethal viruses that cause viral hemorrhagic fever have been discovered, two of which are shown in the Figure below . Ebola outbreaks have been limited mainly to remote areas of the world. However, they have gained extensive media attention because of the high mortality rate—23 percent to 90 percent—depending on the strain. The primary hosts of the viruses are thought to be apes in west central Africa, but the virus has also been isolated from bats in the same region. |
SciQ | SciQ-332 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
Unlike prokaryotic cells, dna and rna synthesis in eukaryotic cells occurs in a separate compartment from synthesis of what? | [
"membrane",
"acids",
"phenotype",
"protein"
] | D | In eukaryotic cells, DNA and RNA synthesis occur in a separate compartment from protein synthesis. In prokaryotic cells, both processes occur together. What advantages might there be to separating the processes? What advantages might there be to having them occur together? The size of the genome in one of the most well-studied prokaryotes, E. coli, is 4.6 million base pairs (approximately 1.1 mm, if cut and stretched out). So how does this fit inside a small bacterial cell? The DNA is twisted by what is known as supercoiling. Supercoiling means that DNA is either under-wound (less than one turn of the helix per 10 base pairs) or over-wound (more than 1 turn per 10 base pairs) from its normal relaxed state. Some proteins are known to be involved in the supercoiling; other proteins and enzymes such as DNA gyrase help in maintaining the supercoiled structure. Eukaryotes, whose chromosomes each consist of a linear DNA molecule, employ a different type of packing strategy to fit their DNA inside the nucleus (Figure 14.11). At the most basic level, DNA is wrapped around proteins known as histones to form structures called nucleosomes. The histones are evolutionarily conserved proteins that are rich in basic amino acids and form an octamer. The DNA (which is negatively charged because of the phosphate groups) is wrapped tightly around the histone core. This nucleosome is linked to the next one with the help of a linker DNA. This is also known as the “beads on a string” structure. This is further compacted into a 30 nm fiber, which is the diameter of the structure. At the metaphase stage, the chromosomes are at their most compact, are approximately 700 nm in width, and are found in association with scaffold proteins. In interphase, eukaryotic chromosomes have two distinct regions that can be distinguished by staining. The tightly packaged region is known as heterochromatin, and the less dense region is known as euchromatin. Heterochromatin usually contains genes that are not expressed, and is found in the regions of the centromere and telomeres. The euchromatin usually contains genes that are transcribed, with DNA packaged around nucleosomes but not further compacted. |
SciQ | SciQ-333 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
What important organelle (that would otherwise be centrally located and crucial to the cell's survival) do prokaryotic cells lack? | [
"electrons",
"protons",
"molecules",
"nucleus"
] | D | Cell division is simpler in prokaryotes than eukaryotes because prokaryotic cells themselves are simpler. Prokaryotic cells have a single circular chromosome, no nucleus, and few other organelles. Eukaryotic cells, in contrast, have multiple chromosomes contained within a nucleus, and many other organelles. All of these cell parts must be duplicated and then separated when the cell divides. A chromosome is a molecule of DNA, and will be the focus of a subsequent concept. |
SciQ | SciQ-334 | neuroscience
Title: What is the function of nodes of Ranvier in axons? In a neuroscience class I'm taking, it was explained that myelin covers axons in sections, the uncovered sections are called nodes of Ranvier, and signals propagate much faster in the covered sections.
But if it is faster for signals to propagate along myelinated regions of the axon, why doesn't the entire axon get covered by myelin? Wouldn't that make it faster? Every signal rapidly fades out with distance if it is not amplified. So if the whole axon were covered with myelin, action potentials wouldn't reach their target. Each Ranvier node can be seen as an active signal repeater.
The following is multiple choice question (with options) to answer.
What is the outer layer of an axon that acts like a layer of insulation, similar to the plastic that encases an electrical cord? | [
"layer sheath",
"nerve sheath",
"myelin sheath",
"lipids sheath"
] | C | The axon of many neurons has an outer layer called a myelin sheath (see Figure above ). Myelin is a lipid produced by a type of a glial cell known as a Schwann cell. The myelin sheath acts like a layer of insulation, similar to the plastic that encases an electrical cord. Regularly spaced nodes, or gaps, in the myelin sheath allow nerve impulses to skip along the axon very rapidly. |
SciQ | SciQ-335 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
What occurs when some members of a species become geographically separated? | [
"allopatric speciation",
"symbiotic speciation",
"divergent speciation",
"reflective speciation"
] | A | New species arise in the process of speciation. Allopatric speciation occurs when some members of a species become geographically separated. They then evolve genetic differences. If the differences prevent them from interbreeding with the original species, a new species has evolved. Sympatric speciation occurs without geographic separation. |
SciQ | SciQ-336 | evolution, mammals, marine-biology
The question remains: why? The most likely explanation is that cetaceans evolved to exploit an unfilled ecological niche or adapted to new niches that formed as a result of plate tectonics or other types of environmental changes that occurred 50-55 million years ago. The niche describes all of the living and non-living resources needed by an organism to survive. Although land-based mammals were increasing in diversity, few or none were present in the oceans. The basic hypothesis is that the early whale-like artiodactyls, like Indohyus and Pakicetus were land-based (terrestrial) mammals that spent most of their time near the water's edge. Over time, they adapted to the niches in the ocean. Fossils like Ambulcetus and Rodhocetus showed clear evidence of swimming ability, with flattened tails and the enlarged rear feet. In addition, the nostrils shifted from the front of the face to the top of the head, which we recognize as the blowhole.
The shift to the aquatic habitat allowed these species to exploit resources that were not available to land-based mammals, thereby reducing competition for the resources. Reduced competition allows more individuals to survive and reproduce.
Similar scenarios are very likely for other marine mammals, such as seals or manatees. They evolved to take advantage of ecological niches that were not filled by other organisms. This basic concept, evolving to fill available niches, is a common outcome of the evolutionary process.
The of adaptation of cetaceans and other mammals to the oceans may be similar to that of the hippopotamus. Hippos spend most of their time in the water, and they show many adaptations that allow them to live in the aquatic environment. The eyes and nostrils of the hippo are high on the head, which allows them to remain almost entirely submerged but still see and smell, as shown below.
(Hippo photo by Johannes Lunberg, Flickr Creative Commons.)
Hippos feed underwaters, they are heavy enough to walk on the bottom of the river, and the mate and give birth underwater. The young can suckle underwater. Clearly, hippos seem to be another mammal that is "returning to water." Similar types of processes must have occurred in cetaceans for them to adapt to the marine habitat.
The following is multiple choice question (with options) to answer.
What creatures evolved from a lobe-finned lungfish ancestor? | [
"horses",
"mice",
"birds",
"amphibians"
] | D | Fossil evidence shows that amphibians evolved about 365 million years ago from a lobe-finned lungfish ancestor. As the earliest land vertebrates, they were highly successful. Some of them were much larger than today’s amphibians. For more than 100 million years, amphibians remained the dominant land vertebrates. Then some of them evolved into reptiles. Once reptiles appeared, with their amniotic eggs, they replaced amphibians as the dominant land vertebrates. |
SciQ | SciQ-337 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What is the term for a mixture of two or more substances that has the same composition throughout? | [
"fluid",
"structure",
"solution",
"simple liquid"
] | C | Water is the main ingredient of many solutions. A solution is a mixture of two or more substances that has the same composition throughout. Some solutions are acids and some are bases. To understand acids and bases, you need to know more about pure water. In pure water (such as distilled water), a tiny fraction of water molecules naturally breaks down to form ions. An ion is an electrically charged atom or molecule. The breakdown of water is represented by the chemical equation. |
SciQ | SciQ-338 | parasitology
Title: Giardia lamblia cases of infections I am wondering if anyone has seen a data of Giardiasis (Giardia Lamblia) cases in different countries on the world? I have found for different diseases and also for 'diarrhoea diseases' in general, but I need especially for Giardia Lamblia.
Any suggestion where I can try to look for this data will be useful.
Thank you very much! If you have or can get access to it, you might try looking in the Incidence and Prevalence database: http://thomsonreuters.com/incidence-and-prevalence-database/
Another possibility is the GIDEON database: http://www.gideononline.com/. It is possible to sign up for a 15-day trial.
For Europe, statistics are available from the WHO CISID at http://data.euro.who.int/cisid/ (select "all infectious diseases", then "Giardiasis").
The WHO does not have any global statistics available on their website, so otherwise you might have to piece together data from individual publications. Some examples:
Thailand, 2005: http://www.ncbi.nlm.nih.gov/pubmed/16438174
Germany, 2006: http://www.ncbi.nlm.nih.gov/pubmed?term=19404678
United States, 2006-2008: http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5906a2.htm
Portugal, 2002-2008: http://www.parasitesandvectors.com/content/5/1/22
Quatar, 2008: http://www.parasitesandvectors.com/content/4/1/211
Tajikistan, 2009: http://www.parasitesandvectors.com/content/4/1/195
Ivory Coast, 2009: http://www.parasitesandvectors.com/content/4/1/96
Tanzania, 2011: http://www.parasitesandvectors.com/content/6/1/3
Ghana, 2006-2009: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170632/?report=classic
The following is multiple choice question (with options) to answer.
What are flagellate protozoa that cause giardiasis? | [
"giardia",
"diatoms",
"plankton",
"fungus"
] | A | Giardia are flagellate protozoa that cause giardiasis . The parasites enter the body through food or water that has been contaminated by feces of infected people or animals. The protozoa attach to the lining of the host’s small intestine, where they prevent the host from fully absorbing nutrients. They may also cause diarrhea, abdominal pain, and fever. A picture of a Giardia protozoan opens this concept. |
SciQ | SciQ-339 | biochemistry, dna, rna
Title: Can a dNTP be built into a RNA strand? DNA consists of deoxyribonucleotides, RNA consists of ribonucleotides. They differ mainly (apart from the uracil / thymine difference) in the sugar part, the deoxyribose and the ribose. Those two molecules differ in the hydroxy group in the ribose which is only a single proton in the deoxyribose. This part of the sugar molecule is not directly involved in binding reactions, nevertheless it causes the whole difference in RNA and DNA.
I wonder: could a dNTP be used in an RNA strand (or vice versa)? Is it chemically possible that we have a RNA molecule that contains a dNTP next to its NTPs? This is rather easy to do if you synthesize oligonucleotides chemically and not enzymatically. This is typically done using phosphoramidite chemistry, and it allows for the synthesis of chimeric RNA/DNA oligos. You can even incorporate modified nucleosides like 2'-O-Me or LNA.
This is typically done if you want to change the properties of an oligo, e.g. if you want to make it resistant to degradation by enzymes.
The following is multiple choice question (with options) to answer.
Rna and dna are types of what biochemical compounds containing the elements carbon, hydrogen, oxygen, nitrogen, and phosphorus? | [
"hormones",
"amino acids",
"nitrous acids",
"nucleic acids"
] | D | Nucleic acids are one of four classes of biochemical compounds. (The other three classes are carbohydrates, proteins, and lipids. ) Nucleic acids include RNA (ribonucleic acid) as well as DNA (deoxyribonucleic acid). Both types of nucleic acids contain the elements carbon, hydrogen, oxygen, nitrogen, and phosphorus. |
SciQ | SciQ-340 | neuroscience, brain, neurophysiology, development, synapses
Title: How do neurons find each other? Neurons form complicated networks in brains, but their connections can't be random (at least not entirely). Brains function similarly among all members of individual species, and that functionality is largely dependent on neuron organization. Furthermore, various brain regions have predictable functions, and there are even parts of the brain where specific cells carry out specialized functions (place cells are an interesting example).
Great! We know neurons can organize into very complex networks, but how? They need to find each other, somehow.
The best I can guess is that either:
Neurons find other target neurons with specific chemical signals.
Neurons don't "find" each other, exactly, but grow in predetermined shapes from from set locations. In this case, the connections would simply be due to neurons bumping into each other as they grow in their predetermined paths.
Or both.
In the first case, there would be a mechanism for searching each other out. In the second, there would be a mechanism for staying in one spot (and growing from there). What are the names of said mechanisms? How do I find out more about them? Q: We know neurons can organize into very complex networks, but how?
The answer is your first guess: Neurons find other target neurons with specific chemical signals.
Q: What are the names of said mechanisms?
This process is called axon guidance, by which the growth cones of developing axons are directed to reach their targets. This process depends upon a slew of cellular and molecular cues. The first axons to grow in any particular brain region are called pioneer axons and are the most dependent upon these cues. Later axons are able to follow (and diverge from) previous axons by the interaction of cell adhesion molecules on their surfaces. Dendritic development is also important for your question, but dendrites tend not to travel as far.
Here are some of the molecules that we know to participate in axon guidance:
Cell adhesion molecules and substrate adhesion molecules, including IgSF CAMs and cadherins
Some chemokines, e.g. CXCL12
Netrins, ephrins, and semaphorins
Slits, via the Slit-Robo cell signaling pathway
Developmental morphogens, e.g. Wnts and Hedgehog
The following is multiple choice question (with options) to answer.
What are the contacts between neurons called? | [
"electrodes",
"neurapses",
"impulses",
"synapses"
] | D | 12.5 Communication Between Neurons The basis of the electrical signal within a neuron is the action potential that propagates down the axon. For a neuron to generate an action potential, it needs to receive input from another source, either another neuron or a sensory stimulus. That input will result in opening ion channels in the neuron, resulting in a graded potential based on the strength of the stimulus. Graded potentials can be depolarizing or hyperpolarizing and can summate to affect the probability of the neuron reaching threshold. Graded potentials can be the result of sensory stimuli. If the sensory stimulus is received by the dendrites of a unipolar sensory neuron, such as the sensory neuron ending in the skin, the graded potential is called a generator potential because it can directly generate the action potential in the initial segment of the axon. If the sensory stimulus is received by a specialized sensory receptor cell, the graded potential is called a receptor potential. Graded potentials produced by interactions between neurons at synapses are called postsynaptic potentials (PSPs). A depolarizing graded potential at a synapse is called an excitatory PSP, and a hyperpolarizing graded potential at a synapse is called an inhibitory PSP. Synapses are the contacts between neurons, which can either be chemical or electrical in nature. Chemical synapses are far more common. At a chemical synapse, neurotransmitter is released from the presynaptic element and diffuses across the synaptic cleft. The neurotransmitter binds to a receptor protein and causes a change in the postsynaptic membrane (the PSP). The neurotransmitter must be inactivated or removed from the synaptic cleft so that the stimulus is limited in time. The particular characteristics of a synapse vary based on the neurotransmitter system produced by that neuron. The cholinergic system is found at the neuromuscular junction and in certain places within the nervous system. Amino acids, such as glutamate, glycine, and gamma-aminobutyric acid (GABA) are used as neurotransmitters. Other neurotransmitters are the result of amino acids being enzymatically changed, as in the biogenic amines, or being covalently bonded together, as in the neuropeptides. |
SciQ | SciQ-341 | inorganic-chemistry, coordination-compounds, reference-request, color, chemical-formula
Potassium Ferrocyanide, $\ce{K4[Fe(CN)6]}$, produces in solutions of ferrous salts, with complete exclusion of air, a white precipitate of potassium ferrous ferrocyanide or of ferrous ferrocyanide, depending upon whether one or two molecules of ferrous salt react with one molecule of potassium ferrocyanide:
$$\ce{K4[Fe(CN)6] + FeSO4 <=> K2SO4 + K2Fe[Fe(CN)6]}$$
$$\ce{K4[Fe(CN)6] + 2 FeSO4 <=> 2 K2SO4 + Fe2[Fe(CN)6]}$$
Although both of the above salts are white, a light-blue color is almost always obtained, because the precipitate is immediately oxidized somewhat by the air, forming the ferric salt of hydroferrocyanic acid (Prussian blue):
$$\ce{6 Fe2[Fe(CN)6] + 6 H2O + 3 O2 <=> $\underset{\text{Prussian blue}}{\ce{2 Fe4[Fe(CN)6]3}}$ + 4 Fe(OH)3}$$
The following is multiple choice question (with options) to answer.
What is the color of the powder of a mineral? | [
"organic",
"gray",
"streak",
"blue"
] | C | Streak is the color of the powder of a mineral. To do a streak test, you scrape the mineral across an unglazed porcelain plate. The plate is harder than many minerals, causing the minerals to leave a streak of powder on the plate. The color of the streak often differs from the color of the larger mineral sample, as Figure below shows. |
SciQ | SciQ-342 | botany, mathematical-models, statistics, biostatistics, migration
Title: Biostatistics: Pollen dispersal directionality What Information am I looking for?
Think about a tree that is sending pollen all over the place. Because of wind, most pollen grain will go toward one direction. Imagine, we split the 2D area around the tree where pollen grains fall into two half disks of equal size. We chose the disks so that the number of pollen grains falling into one half-disk is minimized and the quantity of pollen falling in the other half-disk is maximized.
The information I need is what proportion of pollen grain falls into each disk? Is it $\frac{0.5}{0.5}$ (in which case the wind would have no effect) or is it something like $\frac{0.8}{0.2}$?
Where to get the information from?
I was reading this paper about pollen dispersal directionality and was trying to extract the info I need.
On pages 4 and 5 they explain their analysis under the section statistical procedure. More specifically, in the first paragraph of the 5th page, they seem to describe the meaning of the parameters that are trying to estimate. One of them is the so-called directionality parameter $\delta$. I don't understand how to interpret this parameter $\delta$. This parameter is part of a logistic regression I think (although the authors do not characterize it as such) of "mating success" $y$ against variables $d$ ("distance") and $h$ ("height") and an angular variable $a = \cos(\alpha_0 - \alpha)$. ($\alpha_0$ is the "presumed prevailing direction of effective pollen dispersal," which apparently is not estimated from these data.) The corresponding parameters of the model are $\beta$, $\gamma$, and $\delta$, respectively, hence
$$\phi_j = \Pr(y_j = 1) = \frac{\exp\left(\beta d_j + \gamma h_j + \delta a_j\right)}{\sum_{k=1}^r \exp\left(\beta d_k + \gamma h_k + \delta a_k\right)}$$
The following is multiple choice question (with options) to answer.
What basic plant structure facilitates dispersal of pollen and fruit by raising reproductive structures? | [
"leaf",
"stem",
"root",
"flower"
] | B | |
SciQ | SciQ-343 | everyday-chemistry, biochemistry, food-chemistry, terminology
As the discovery of the vitamins progressed, it was realized that “Factor B”
consisted of a number of chemically and physiologically distinct compounds.
Before they were identified chemically, they were given a logical series of alphanumeric
names: B1, B2, and so forth
From a pharmaceutical perspective...
The "complexity" of vitamin B compounds simply suggest a combination of different compounds that fall under this family. Because vitamin
compounds are required in relatively large amounts compared to fat soluble counterparts, it makes sense to combine them as supplements rather than packaging
7+ pharmaceutical products as "Vitamin B1", "Vitamin B2", "Vitamin B3"... suplements, it creates more confusion and non-compliance instead their systematic names are used for example pyridoxine injection (vitamin B6), Nicotinamide tablets but where multivitamin are prescibed its just a "complex" of there compounds usually 5-6 of these "B" vitamins.
It is important to note that such compounds are requirement in very small quantities/day, and overdosing (through such these compounds can cause undesirable side effects).
Other forms of vitamins (fat soluble) are equally important but most of them are either stored in body in reserves e.g Vitamin A, others like Vitamin K are synthesised in the body by bacteria hence are needed in very small amounts
This is the chief reason why there are fewer supplements of such vitamins (although they may be needed in special cases).
For a compound to be considered a vitamin, it must be shown to be a
dietary essential. Its elimination from the diet must result in a
more-or-less clearly defined deficiency disease, and restoration must
cure or prevent that deficiency disease.
Several forms of vitamin D?
Vitamin D is not strictly a vitamin, rather it is the precursor of one
of the hormones involved in the maintenance of calcium homeostasis and
the regulation of cell proliferation and differentiation, where it has
both endocrine and paracrine actions.
The following is multiple choice question (with options) to answer.
What type of compound is essential to life? | [
"carbon",
"water",
"oxygen",
"nitrogen"
] | B | Water is essential to life because chemical reactions within cells take place in water. Most people can survive only a few days without consuming water to replace their water losses. How do you lose water?. |
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