source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-5744 | biochemistry, molecular-biology, cell-biology, physiology
Title: Which organelle synthesizes glycogen phosphorylase and why? I know that glycogen phosphorylase is not synthesized in the rough endoplasmic reticulum of liver cells, unlike many other proteins such as insulin receptor, lysosomal enzyme and serum albumin. I would like to know the organelle where glycogen phosphorylase is made and why it is made there. Protein translation occurs via ribosomes bound to strands of messenger RNA in the cytoplasm; these structures are called polysomes but don't have a membrane surrounding them so you might not want to call them organelles. Polysomes making proteins destined for secretion, for the plasma membrane, or for some organelles (like your examples) are directed to the endoplasmic reticulum via a signal peptide typically near the beginning of the translated sequence. The combination of polysomes and endoplasmic reticulum is what is called rough endoplasmic reticulum. See this Wikipedia page for a more complete explanation of how particular proteins are targeted to their correct locations.
The following is multiple choice question (with options) to answer.
What are small organelles and are the site of protein synthesis? | [
"ribosomes",
"nucleus",
"chloroplasts",
"vacuoles"
] | A | Ribosomes are small organelles and are the site of protein synthesis. Ribosomes are found in all cells. |
SciQ | SciQ-5745 | human-biology, cancer, systems-biology
Title: How does cancer of the larynx (laryngeal cancer) affect the respiratory system? The larynx is part of the respiratory system and is responsible for producing sound (our voices). My question is how cancer in the larynx (voice box) affect the respiratory system overall? I appreciate any answer, but if it's not too inconvenient, please don't use too complex terminology (I'm in grade 10 Canada).
Thanks According to this website:
http://www.spirometry.guru/fvc.html
it causes difficulty with inhalation but exhalation is normal...
"Typically the expiratory part of the F/V-loop is normal: the
obstruction is pushed outwards by the force of the expiration."
"During inspiration the obstruction is sucked into the trachea with
partial obstruction and flattening of the inspiratory part of the
flow-volume loop."
the exact symptoms of a laryngeal tumor depends on where it is located on the larynx... above the vocal cords, on the vocal cords, or below the vocal cords...
but more generally:
anatomy:
mouth/nose-->pharynx-->larynx-->trachea-->bronchi-->lungs
a tracheostomy may be necessary... basically the surgeon makes a connection between the skin outside the throat and the trachea... this bypasses the larynx (as well as pharynx and nose/mouth)...
The following is multiple choice question (with options) to answer.
Lungs, pharynx, larynx, trachea, and bronchi are part of which system? | [
"nervous",
"digestive",
"respiratory",
"neural"
] | C | The organs of the respiratory system include the lungs, pharynx, larynx, trachea, and bronchi. |
SciQ | SciQ-5746 | biochemistry, bioinformatics, homework, growth, systems-biology
Title: Why is it desirable to couple chemical production to growth? I have the following question in systems biology:
a) Draw a graph showing the relationship of growth (Vbio) and Vefni for the system here. (Let the horizontal axis represent Vbio and the vertical axis represent Vefni)
My first thought was that it would simply be straight line from (0.5,0.5) to (1,0). But now I'm thinking that I have to take V4 into account as well.
b) Determine one or more reactions that are such that if they are taken
out the production of M4 is coupled to growth (growth-coupling). Draw a
graph showing the relationship Vbio and Vefni for the mutant.
Here I thought it would be V1 and V4. I'm not sure though because I haven't found a good explanation for what growth-coupling is exactly.
c) Why is it desirable to couple chemical production to growth? i.e. what advantages do those systems have over the ones where no such coupling is present?
Here I have no idea.
Why is it desirable to couple chemical production to growth?
When designing new metabolic pathways for chemical production, one has to keep in mind that the purpose of it is to get scaled up (i.e. to reach industrial size).
From the industrial point of view, the faster/simpler a process is, the better. Growth coupled chemical production means that only one step is necessary in order to produce the desired product (before downstream processes). Otherwise, one would have to produce the biomass first (growth step) and then to proceed to the chemical production step. One step is cheaper and faster than two, not mentioning the intermediary steps that could be necessary (cells washing, centrifugation, filtration ...).
The main drawback of growth coupled chemical production is that the final yield ($mol_{final~product}/mol_{substrate}$) is hindered by biomass production. This can be a real issue if the substrate is expensive.
The following is multiple choice question (with options) to answer.
What is necessary for growth and energy? | [
"nutrients",
"warmth",
"breeding",
"determination"
] | A | |
SciQ | SciQ-5747 | plant-anatomy
Title: Are bryophyte sporangia multicellular? My research on the matter can be summarized in a sentence: "It [sporangium] can be composed of a single cell or can be multicellular" (Source: https://en.wikipedia.org/wiki/Sporangium). Yet there shouldn't be a reply placed between "They are" and "They aren't" test options, speaking of "Are bryophyte sporangia multicellular?". A link to the source where I could ascertain whether the bryophyte sporangia is multicellular (if I could ascertain) is highly appreciated. In Embryophyta (land plants), including bryophytes, the sporangium is usually a multicellular structure.
Perhaps you meant to ask about the number of spore mother cells (SMCs) in each sporangium? That varies across groups. In bryophytes, each sporangium has many SMCs, and accordingly produces a large number of spores. (Contrast this with angiosperms, where a megasporangium [called an ovule] has only one megaspore mother cell.)
References and further reading:
https://courses.lumenlearning.com/boundless-biology/chapter/bryophytes/
https://www.britannica.com/science/plant-development
Image attribution:
By LadyofHats. (Public domain;
https://commons.wikimedia.org/wiki/File:Hornwort_structures.jpg)
The following is multiple choice question (with options) to answer.
Bryophyta is the formal taxonomic name for the phylum that consists solely of what? | [
"grasses",
"mosses",
"trees",
"lichens"
] | B | |
SciQ | SciQ-5748 | dna, dna-sequencing
Except for Red Blood Cells, every somatic cell contains two copies of the autosomal chromosomes and a pair of sex chromosomes, either XX or XY (Assuming an average human being) One set is maternal and one is paternal
Some lymphocytes actually recombine their chromosomes, so their DNA will be functionally different to all of the other somatic cells in the body.
Gametes undergo Meiosis and will be haploid, only containing one copy of each autosomal chromosome and one of the sex chromosomes
Cells accumulate mutations over time. The closest you could probably come to an exact clone of a person is if you harvested one of the cells from the eight-cell stage of development. The other seven are able to go on and produce a viable and healthy person. The harvested cells DNA would be the closest to the DNA that combined in the fertilization of the egg. The next closest would likely be stem cells from cord blood. Then probably neurons, as they tend to divide the least.
As the link you posted said, ATCG can be represented in a two bit code, so for about 6 billion bases, you would need about 1.5GB of storage (You need to capture both sets of chromosomes in order to produce a person).
The following is multiple choice question (with options) to answer.
In humans, how many chromosomes does each somatic cell have? | [
"51",
"36",
"48",
"46"
] | D | |
SciQ | SciQ-5749 | 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.
Like mitochondria, plastids contain their own what? | [
"molecule",
"bacteria",
"riboflavin",
"dna"
] | D | Like mitochondria, plastids contain their own DNA. Therefore, according to endosymbiotic theory, plastids may also have evolved from ancient, free-living prokaryotes that invaded larger prokaryotic cells. If so, they allowed early eukaryotes to make food and produce oxygen. |
SciQ | SciQ-5750 | gravity, water, space, planets
The only detail left is how to get a surface temperature that's in the right range for the surface to be liquid. This depends on the distance from the star, but also on the composition of the atmosphere. On Earth, the atmosphere's composition is mostly due to the action of the biosphere, which keeps the temperature regulated in just the right range for water to be liquid. Perhaps it's possible to imagine life on such a water world, in the form of photosynthesising algae-like organisms, which might play a similar role.
The following is multiple choice question (with options) to answer.
Terrestrial and aquatic are the two basic categories of what, on earth? | [
"dendrites",
"atmospheres",
"biomes",
"substrates"
] | C | 20.3 | Terrestrial Biomes By the end of this section, you will be able to: • Identify the two major abiotic factors that determine the type of terrestrial biome in an area • Recognize distinguishing characteristics of each of the eight major terrestrial biomes Earth’s biomes can be either terrestrial or aquatic. Terrestrial biomes are based on land, while aquatic biomes include both ocean and freshwater biomes. The eight major terrestrial biomes on Earth are each distinguished by characteristic temperatures and amount of precipitation. Annual totals and fluctuations of precipitation affect the kinds of vegetation and animal life that can exist in broad geographical regions. Temperature variation on a daily and seasonal basis is also important for predicting the geographic distribution of a biome. Since a biome is defined by climate, the same biome can occur in geographically distinct areas with similar climates (Figure 20.18). There are also large areas on Antarctica, Greenland, and in mountain ranges that are covered by permanent glaciers and support very little life. Strictly speaking, these are not considered biomes and in addition to extremes of cold, they are also often deserts with very low precipitation. |
SciQ | SciQ-5751 | acid-base
The equilibrium constants for this reaction is
\begin{align}
K &= \frac{a(\ce{A-})\,a(\ce{H3O+})}{a(\ce{HA})\,a(\ce{H2O})}
\approx \frac{c(\ce{A-})\,c(\ce{H3O+})}{c(\ce{HA})\,c(\ce{H2O})}
\approx \frac{K_\mathrm{a}}{c(\ce{H2O})}\\
K_\mathrm{a} &=
\frac{c(\ce{A-})\,c(\ce{H3O+})}{c(\ce{HA})}\\
\mathrm{p}K_\mathrm{a} &= -\lg K_\mathrm{a}.
\end{align}
For a strong acid we can see that the concentration of undissociated acid is (nearly) zero. Therefore we write
\begin{align}
\lim_{c(\ce{HA})\to0} \left(K_\mathrm{a}\right) &= \infty&
&\therefore&
\lim_{c(\ce{HA})\to0}\left(\mathrm{p}K_\mathrm{a}\right) &= -\infty.
\end{align}
Strictly speaking, in aqueous solutions the acidity constants cannot be measured, since the hydronium ion is the strongest acid in this medium.
So in priniciple, the value that separates strong from weak acids would be the $\mathrm{p}K_\mathrm{a}$ of the hydronium ion. With that we arrive at a completely new problem, which is quite efficiently discussed here: What is the pKa of the hydronium, or oxonium, ion (H3O+)?
The following is multiple choice question (with options) to answer.
When dissolved in water, what do strong acids transfer to the solvent completely? | [
"acidic electrons",
"acidic protons",
"acidic proteins",
"acidic neutrons"
] | B | Strong acids completely transfer their acidic protons to the solvent when dissolved in water. When a weak acid is dissolved in water, most of the molecules will retain their acidic protons, and only a small percentage will dissociate. |
SciQ | SciQ-5752 | ionic-compounds
As ionic solids are added to water, water molecules proceed to surround each ion on the surface of the solid, forming a sphere of hydration. In the process, ions are separated from each other.
The $\delta^-$ charge on the oxygen atoms of water are attracted to cations and inversely, repels the $\delta^+$ hydrogen atoms. Thus, for cations, the oxygens of water point inward, and for anions, the hydrogens face inward respectively. The most important thing is that the ion-dipole interactions and separation of ions with little change in energy.
We can relate the potential energy of the ions to the two partial charges of a polar molecule like water:
$$ E_p \propto - \frac{|z|\mu}{r^2}$$
Z is the charge number of the ion and $\mu$ is the dipole moment of the polar molecule. Potential energy is lowered by the interaction between the solvent molecules and the ion. The $r^2$ term indicates that the interaction between ions and dipoles depends more on distance than the charges between two ions.
Thus, for hydration to occur, ion-dipole interactions must occur at the surface of the ion, and thus, ion-dipole interactions are strong for small, highly charged ions such as $\ce{Mg^{2+}}$, $\ce{Li^{2+}}$ etc.
$\ce{AgCl}$ is very slightly soluble in water and will not dissociate into it's ions. $\ce{HF}$ is a weak acid thus it does not deprotonate easily.
The following is multiple choice question (with options) to answer.
On the atomic level, the dissolution of an ionic compound occurs when water interacts with the what in the crystal lattice? | [
"atoms",
"fractals",
"ions",
"particles"
] | C | The last property above requires some additional explanation. We are all familiar with the process of dissolution on a large scale. If you stir a spoonful of salt into a glass of water, the salt crystals are broken down and seem to disappear into the water. On the atomic level, the dissolution of an ionic compound occurs when water interacts with the ions in the crystal lattice, causing the lattice to break apart ( Figure below ):. |
SciQ | SciQ-5753 | observational-astronomy, telescope, amateur-observing, optics, deep-sky-observing
Use the brightest stars on your journey to guide your way. Look for shapes: triangles of stars of a similar brightness make great signposts.
If you find that you can see more stars in the eyepiece than the star map is showing you, then you might want to change to one of the other applications. SkEye is free and has a limited catalogue. The other two are not free but have more extensive catalogues.
A great desktop application for this is KStars: it has a star hopping tool which will generate set of instructions, given a start point, and end point, and an eyepiece.
I find star hopping to be a fun way to hunt down targets in the sky. For me it makes the sense of discovery even sweeter. Other people find it dull and would rather use a Go-To mount to do the work for them.
Give it a try and find out which type of person you are - either way is perfectly valid :-)
Filters
In a comment, D.Halsey suggests using a light pollution filter. Unfortunately these are less useful than they were. These days many cities have 'upgraded' to LED lighting, which has the unfortunate side-effect of casting light which covers the full visible spectrum. Light pollution filters worked by filtering out the yellow light given off by the old sodium street lights. Against modern LED lights they don't do very much. If you're fortunate then you might live in an area which hasn't yet changed the street lighting over from sodium to LED - in which case go ahead with the light pollution filter!
Filters which do work - on certain nebulae at least - are the O-III (doubly ionised oxygen) and Ha (hydrogen alpha) filters, or one of the several "nebula filters" which allow both of these bands through.
They don't make the objects brighter - they work by making everything else darker. But they do work. I've seen several nebulae from the city which were impossible to see without them.
Just bear in mind that, because they work by dimming everything except the nebula, they're best used with your lowest power eyepiece: the one that gives the biggest exit pupil, and therefore the brightest view.
Aperture and/or darker skies
The following is multiple choice question (with options) to answer.
What is one method to observe nebulae? | [
"microscope",
"mirror",
"kaleidoscope",
"telescope"
] | D | Nebulae can be spotted with the naked eye or simple telescopes. |
SciQ | SciQ-5754 | electromagnetism, magnetic-fields, electromagnetic-induction
Title: Usefulness of an iron core in a magnetic coil used to generate current I wish to light a LED by moving a permanent magnet relative to an inductor consisting of a coil of copper wire. Can I increase efficiency (current produced for a given magnet motion) by using an iron or ferrite core in my magnetic coil? Of course, that is what is regularly done in all common AC generators - the coils are wound on special steel poles with high permeability. Well placed ferromagnetic core can increase the induced emf in wires by three and even more orders of magnitude.
The following is multiple choice question (with options) to answer.
When alternating primary current passes through coil p, it does what to the iron core? | [
"creates it",
"electrilizes it",
"heats it",
"magnetizes it"
] | D | As you can see in Figure above , a transformer consists of two wire coils wrapped around an iron core. When alternating primary current passes through coil P, it magnetizes the iron core. Because the current is alternating, the magnetic field of the iron core keeps reversing. This changing magnetic field induces alternating current in coil S, which is part of another circuit. In Figure above , coil P and coil S have the same number of turns of wire. In this case, the voltages of the primary and secondary currents are the same. However, when the two coils have different numbers of turns, the voltage of the secondary current is different than the voltage of the primary current. Both cases are illustrated in Figure below . |
SciQ | SciQ-5755 | thermodynamics, material-science, phase-transition, states-of-matter
Title: Why does matter exist in 3 states (liquids, solid, gas)? Why does matter on the earth exist in three states? Why cannot all matter exist in only one state (i.e. solid/liquid/gas)? The premise is wrong. Not all materials exist in exactly three different states; this is just the simplest schema and is applicable for some simple molecular or ionic substances.
Let's picture what happens to a substance if you start at low temperature, and add ever more heat.
Solid
At very low temperatures, there is virtually no thermal motion that prevents the molecules sticking together. And they stick together because of various forces (the simplest: opposite-charged ions attract each other electrostatically). If you picture this with something like lots of small magnets, it's evident enough that you get a solid phase, i.e. a rigid structure where nothing moves.
Actually though:
Helium won't freeze at any temperature: its ground state in the low-temperature limit at atmospheric pressure is a superfluid. The reason is that microscopically, matter does not behave like discrete magnets or something, but according to quantum mechanics.
There is generally not just one solid state. In the magnet analogy, you can build completely different structures from the same components. Likewise, what we just call “ice” is actually just one possible crystal structure for solid water, more precisely called Ice Ih. There are quite a lot of other solid phases.
Liquid
Now, if you increase temperature, that's like thoroughly vibrating your magnet sculpture. Because these bonds aren't infinitely strong, some of them will release every once in a while, allowing the whole to deform without actually falling apart. This is something like a liquid state.
Actually though:
The following is multiple choice question (with options) to answer.
What state of matter exists if particles do not have enough kinetic energy to overcome the force of attraction between them? | [
"liquid",
"solid",
"plasma",
"gas"
] | B | If particles do not have enough kinetic energy to overcome the force of attraction between them, matter exists as a solid. The particles are packed closely together and held rigidly in place. All they can do is vibrate. This explains why solids have a fixed volume and a fixed shape. |
SciQ | SciQ-5756 | particle-physics, nuclear-physics, atomic-physics, radiation, radioactivity
Title: What is the importance of excited states in the emission of gamma radiation during alpha decay? Let's suppose that during a hypothetical alpha decay of a nucleus X, has two excited states (such as 2.3 mEV and 0.9 mEV) are respectively fed.
The question arises here: what would would be the energy of the gamma rays that could be emitted?
My work: Would the alpha decay energy into the superior excited state (2.3 mEV) be equal to the gamma ray de-exitation from the superior excited state to the inferior excited state (0.9 mEV)?
And then,will the energy when the inferior excited state falls into the ground state be equal to 0.9 mEV?
So, I´m not sure if what we are looking for is a distribution of the energies emitted during this decay, which could vary, OR the total energy of the gamma rays that were emitted, which would be a sum of Excited State 2 -> Excited State 1 and Excited State 1 -> Ground State (1,4 + 0,9= 2,3 mEV)
Thanks for your help. Here's a level scheme for cobalt-60 which I decorated recently to answer another question about gamma emission. The 99.9% decay pathway is highlighted. This is a beta emitter instead of an alpha emitter, but I don't think that's a big deal for your question.
The following is multiple choice question (with options) to answer.
What is the“packet” of energy called that the nucleus emits during gamma decay? | [
"transient particle",
"radioactive particle",
"ultraviolet particle",
"gamma particle"
] | D | Gamma rays are produced during gamma decay of an excited nucleus. During gamma decay, the nucleus emits a “packet” of energy called a gamma particle. |
SciQ | SciQ-5757 | metallurgy, nuclear-chemistry, geochemistry
Title: Why are rare earth metals and platinum group metals are often found clustered together in ores Rare earth and platinum group metals are often found clustered together in the earth's crust. Mining for platinum, for instance, also yields Rhodium and Ruthenium belonging to the same group. Likewise, rare earth elements such as Neodymium, Europium and Samarium also cooccur in the same ore, so much so, that they are difficult to chemically separate.
It could be reasoned that it's the result of nucleogenesis where elements are formed consecutively based on their atomic number. While it might explain the first row and the second row of each group, where each metal is only one atomic number apart, it doesn't explain why metals from both rows are found together which are much further apart.
Alternatively, the similar chemistry of each group could explain the clustering. The two groups are the only group with this property. It fails to explain, however, how these metals found each other in a molten soup of heterogeneous elements. There may be some geological factors in the clustering, but it's unclear.
Why are the two groups of elements found clustered together? The factors that generate mineral concentrations are complex and often only partly known
Introduction: geology is complicated
The one thing we can be very certain about is is that the distribution of minerals in the earth's crust has very little to do with the primordial origins of the component elements (that is where they came from in the early solar system and how they were originally generated). Most "heavy" elements are originally formed in the cores of supernovae and not in either the big bang or in normal stars.
The distribution of elements in the earth is mostly unrelated to the cosmic origins of elements because the earth's crust is not static but is frequently churned up by a variety of processes on a geological timescale. If we go back far enough in the history of the planet, everything was molten and this allowed some of the denser components to separate out before the surface cooled enough to be solid. The led to the core being mostly metallic (and consisting of mostly iron and nickel). Higher layers contain less dense minerals containing a lot of silicate minerals. At the top there is a thin layer, the crust, which is where we find useful minerals and it is even more concentrated in silicate minerals and even less dense.
The following is multiple choice question (with options) to answer.
The movement of molten metal in earth's outer core creates? | [
"earthquakes",
"the stellar field",
"the magnetic field",
"the gravitational field"
] | C | The magnetic field has north and south poles. The magnetic poles do not exactly match the geographic poles. So the North Magnetic Pole is not the same as the geographic North Pole. The same is true of the South Pole. The magnetic field is created by the movement of molten metal in the outer core. |
SciQ | SciQ-5758 | 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.
Mechanical churning of food in what organ serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme? | [
"liver",
"gall bladder",
"kidneys",
"stomach"
] | D | saliva. Although there may be a tendency to think that mechanical digestion is limited to the first steps of the digestive process, it occurs after the food leaves the mouth, as well. The mechanical churning of food in the stomach serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme. Segmentation, which occurs mainly in the small intestine, consists of localized contractions of circular muscle of the muscularis layer of the alimentary canal. These contractions isolate small sections of the intestine, moving their contents back and forth while continuously subdividing, breaking up, and mixing the contents. By moving food back and forth in the intestinal lumen, segmentation mixes food with digestive juices and facilitates absorption. In chemical digestion, starting in the mouth, digestive secretions break down complex food molecules into their chemical building blocks (for example, proteins into separate amino acids). These secretions vary in composition, but typically contain water, various enzymes, acids, and salts. The process is completed in the small intestine. Food that has been broken down is of no value to the body unless it enters the bloodstream and its nutrients are put to work. This occurs through the process of absorption, which takes place primarily within the small intestine. There, most nutrients are absorbed from the lumen of the alimentary canal into the bloodstream through the epithelial cells that make up the mucosa. Lipids are absorbed into lacteals and are transported via the lymphatic vessels to the bloodstream (the subclavian veins near the heart). The details of these processes will be discussed later. In defecation, the final step in digestion, undigested materials are removed from the body as feces. |
SciQ | SciQ-5759 | fluid-dynamics, air
Title: How can a constant mass flow rate of air coming out of a compressed air tank be maintained? If I have an air tank filled with air at, say, 4 bar, how would I be able to maintain a constant mass flow rate coming out of that tank, with the air flowing out into the atmosphere? I would imagine you increase the orifice as the internal pressure of the tank decreases. What equations would I use to describe the increase in orifice area? you can use a pressure regulator, which will automatically choke the flow out of the tank so as to maintain a nearly-constant output pressure as the tank empties itself. These devices are used throughout the engineering world to maintain constant outlet pressure regardless of source pressure.
The following is multiple choice question (with options) to answer.
A constant and plentiful supply of oxygen is required in order to maintain a high rate of what? | [
"digestion",
"cell division",
"magnesium",
"metabolism"
] | D | Keeping the rate of metabolism high takes a constant and plentiful supply of oxygen. That’s because cellular respiration, which produces energy, requires oxygen. The lungs and heart of mammals are adapted to meet their oxygen needs. |
SciQ | SciQ-5760 | botany, plant-physiology, ecology, virology, host-pathogen-interaction
Note about symbiosis - comes in reaction to @Gerhard's comment
Different authors use the word symbiosis differently. From wikipedia:
The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).4 After 130+ years of debate,5 current biology and ecology textbooks now use the latter "de Bary" definition or an even broader definition (i.e. symbiosis = all species interactions), with the restrictive definition no longer used (i.e. symbiosis = mutualism)
The following is multiple choice question (with options) to answer.
Organisms interact with each other and what else? | [
"atmospheric environment",
"outside enviroment",
"physical environment",
"thermal environment"
] | C | |
SciQ | SciQ-5761 | earthquakes, waves, scale
Title: If a very huge Earthquake occured anywhere on Earth could waves emerge to come together again on the opposite side? Suppose that a super-powerful earthquake occurred anywhere on Earth, say one with the value 10 on Richter's scale. The quake can have any value but as can be read in a comment below the highest value ever measured was 32 on a superdense star. In that case, it's much more difficult to tear the star apart. The Earth, in contrast, could be torn apart by a quake with value 10 because she is highly less massive.
Suppose the quake was mainly transversal (in a vertical direction). Could it be that correspondingly waves emerged from the center of the quake, traveling the Earth around to come together and reinforced again on the opposite side of the center, with the effect that the quake was felt more strongly on the opposite side of the center than at places halfway from the center (or halfway to the opposite side of the center), to say it in one long breath? Or would too much energy be absorbed from the waves by the Earth to reach the opposite side? It is called "antipodal focusing". See for example Antipodal focusing of seismic waves observed with the USArray.
We present an analysis of the M-w = 5.3 earthquake that occurred in the Southeast Indian Ridge on 2010 February 11 using USArray data. The epicentre of this event is antipodal to the USArray, providing us with an opportunity to observe in details the antipodal focusing of seismic waves in space and time. We compare the observed signals with synthetic seismograms computed for a spherically symmetric earth model
The above paper deals with "body waves" that travel through the interior of the Earth.
There are also Rayleigh waves that travel on the surface and can travel around the Earth several times before dissipating (Wikipedia). Antipodal focusing of seismic waves due to large meteorite impacts on Earth does numerical simulations of surface waves at the antipode of the Chicxulub impact. The waves do not arrive at the antipode at the same time because of Earth’s ellipsoidal shape and different rock properties along their paths.
Isosurfaces of the norm of the peak displacement vector after a vertical impact for the impact hemisphere (left-hand side) and antipodal hemisphere (right-hand side).
The following is multiple choice question (with options) to answer.
What is the center of an earthquake called? | [
"the epicenter",
"the magnitude",
"the impact",
"the core"
] | A | Where an earthquake takes place is described by its focus and epicenter. |
SciQ | SciQ-5762 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
Calvin cycle reactions can be organized into three basic stages: fixation, reduction, and this? | [
"regeneration",
"transformation",
"demarcation",
"creation"
] | A | The Calvin cycle reactions (Figure 5.15) can be organized into three basic stages: fixation, reduction, and regeneration. In the stroma, in addition to CO2, two other chemicals are present to initiate the Calvin cycle: an enzyme abbreviated RuBisCO, and the molecule ribulose bisphosphate (RuBP). RuBP has five atoms of carbon and a phosphate group on each end. RuBisCO catalyzes a reaction between CO2 and RuBP, which forms a six-carbon compound that is immediately converted into two three-carbon compounds. This process is called carbon fixation, because CO2 is “fixed” from its inorganic form into organic molecules. ATP and NADPH use their stored energy to convert the three-carbon compound, 3-PGA, into another three-carbon compound called G3P. This type of reaction is called a reduction reaction, because it involves the gain of electrons. A reduction is the gain of an electron by an atom or molecule. The molecules of ADP and NAD+, resulting from the reduction reaction, return to the light-dependent reactions to be re-energized. One of the G3P molecules leaves the Calvin cycle to contribute to the formation of the carbohydrate molecule, which is commonly glucose (C6H12O6). Because the carbohydrate molecule has six carbon atoms, it takes six turns of the Calvin cycle to make one carbohydrate molecule (one for each carbon dioxide molecule fixed). The remaining G3P molecules regenerate RuBP, which enables the system to prepare for the carbon-fixation step. ATP is also used in the regeneration of RuBP. |
SciQ | SciQ-5763 | botany, homework, terminology, plant-anatomy, tissue
Interfascicular cambium differentiates from parenchyma or collenchyma cells located between the vascular bundles (mainly in stem)
The following is multiple choice question (with options) to answer.
What type of cells are arranged into tightly packed sheaths around the veins of the leaf? | [
"bundle-sheath cells",
"cell walls",
"pattern - sheath cells",
"cellulose"
] | A | |
SciQ | SciQ-5764 | physical-chemistry, stoichiometry, elemental-analysis
Here is my work:
$$
\begin{array}{cccccc}
& \ce{C_{a}H_{b}} & \ce{->} & \ce{CO2} & + & \ce{H2O} \\
\text{masses (g)} & 1.05 & & 3.30 & & 1.35
\end{array}
$$
\begin{align*}
\ce{CO2} &\rightarrow \ce{C} \\
44~\mathrm{g} &\rightarrow 12~\mathrm{g} \\
3.30~\mathrm{g} &\rightarrow x
\end{align*}
$$
x = 0.9~\mathrm{g},~\text{moles of C} = \frac{0.9}{12} = 0.075
$$
\begin{align*}
\ce{H2O} &\rightarrow \ce{2H} \\
18~\mathrm{g} &\rightarrow 2~\mathrm{g} \\
1.35~\mathrm{g} &\rightarrow y
\end{align*}
$$
y = 0.15~\mathrm{g},~\text{moles of H} = \frac{0.15}{1} = 0.15
$$
$$
\text{empirical formula}~\ce{C_{0.075/0.075}H_{0.15/0.075} -> CH2}
$$
$$
\frac{70}{14} = 5
$$
$$
\text{molecular formula is}~\ce{C5H10}
$$ $$\ce{C_{$a$}H_{$b$} + $\left(a+\frac b4\right)$O2 -> $a$CO2 + $\frac{b}{2}$ H2O}$$
The following is multiple choice question (with options) to answer.
How are the number of moles of carbon dioxide gas calculated? | [
"casuistry",
"stoichiometry",
"phytochemistry",
"relativistic"
] | B | The number of moles of carbon dioxide gas is first calculated by stoichiometry. Then the ideal gas law is used to calculate the volume of CO 2 produced. |
SciQ | SciQ-5765 | 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.
What is the name of the blood protein that carries oxygen from the lungs to the body's assorted tissues? | [
"insulin",
"plasma",
"hemoglobin",
"White Blood cells"
] | C | Anemia is a disease that occurs when there is not enough hemoglobin in the blood to carry oxygen to body cells. Hemoglobin is the blood protein that normally carries oxygen from the lungs to the tissues. Anemia leads to a lack of oxygen in organs. |
SciQ | SciQ-5766 | homework-and-exercises, radiation
Title: light beams of the sun
We receive sunlight on earth surface. What type of light beams are these?
Random/Parallel/Converging/Diverging
I think it should be Diverging as Sun is radiating these beams away. But in one book, answer is given as Random, in another it's Parallel. It is difficult to answer this question. An EM wave is generated by vibrating charges and nuclear reactions. Sun is full of vibrating charges and nuclear fusions. Because of this full range of frequencies are emitted. At distances close to sun we observe the directions of waves to be random. But at far away distances the direction of waves seem parallel. Since only parallel waves can have constant separation between them. Converging and diverging waves become distant at longer distances.
The following is multiple choice question (with options) to answer.
The sun and many other light sources produce waves that are randomly this? | [
"amplified",
"colored",
"polarized",
"obfuscated"
] | C | The Sun and many other light sources produce waves that are randomly polarized (see Figure 27.39). Such light is said to be unpolarized because it is composed of many waves with all possible directions of polarization. Polaroid materials, invented by the founder of Polaroid Corporation, Edwin Land, act as a polarizing slit for light, allowing only polarization in one direction to pass through. Polarizing filters are composed of long molecules aligned in one direction. Thinking of the molecules as many slits, analogous to those for the oscillating ropes, we can understand why only light with a specific polarization can get through. The axis of a polarizing filter is the direction along which the filter passes the electric field of an EM wave (see Figure 27.40). |
SciQ | SciQ-5767 | human-biology, human-anatomy
Title: Difference between the spinal cord and vertebrae column What is the difference between the spinal cord and the vertebrae column, they both run through from the head to the abdomen. Does any one have any idea. The vertebral column is a bony, segmented structure that supports the torso/head and thorax. The spinal cord is a bundle of nerves that runs inside the structure of the vertebral column. So - they run together, but are completely separate.
The following is multiple choice question (with options) to answer.
Each vertebral vein also flows into which vein? | [
"trichina",
"xerophyte",
"spiral",
"brachiocephalic"
] | D | The Superior Vena Cava The superior vena cava drains most of the body superior to the diaphragm (Figure 20.36). On both the left and right sides, the subclavian vein forms when the axillary vein passes through the body wall from the axillary region. It fuses with the external and internal jugular veins from the head and neck to form the brachiocephalic vein. Each vertebral vein also flows into the brachiocephalic vein close to this fusion. These veins arise from the base of the brain and the cervical region of the spinal cord, and flow largely through the intervertebral foramina in the cervical vertebrae. They are the counterparts of the vertebral arteries. Each internal thoracic vein, also known as an internal mammary vein, drains the anterior surface of the chest wall and flows into the brachiocephalic vein. The remainder of the blood supply from the thorax drains into the azygos vein. Each intercostal vein drains muscles of the thoracic wall, each esophageal vein delivers blood from the inferior portions of the esophagus, each bronchial vein drains the systemic circulation from the lungs, and several smaller veins drain the mediastinal region. Bronchial veins carry approximately 13 percent of the blood that flows into the bronchial arteries; the remainder intermingles with the pulmonary circulation and returns to the heart via the pulmonary veins. These veins flow into the azygos vein, and with the smaller hemiazygos vein (hemi- = “half”) on the left of the vertebral column, drain blood from the thoracic region. The hemiazygos vein does not drain directly into the superior vena cava but enters the brachiocephalic vein via the superior intercostal vein. The azygos vein passes through the diaphragm from the thoracic cavity on the right side of the vertebral column and begins in the lumbar region of the thoracic cavity. It flows into the superior vena cava at approximately the level of T2, making a significant contribution to the flow of blood. It combines with the two large left and right brachiocephalic veins to form the superior vena cava. Table 20.11 summarizes the veins of the thoracic region that flow into the superior vena cava. |
SciQ | SciQ-5768 | 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.
Almost all plants make food through what process? | [
"photosynthesis",
"glycolysis",
"evolution",
"hydrolysis"
] | A | Almost all plants make food by photosynthesis. |
SciQ | SciQ-5769 | evolution
Title: How to define "evolution"? The standard answer found in intro course to evolutionary biology to the question:
what is evolution?
is:
It is a change in allele frequency over time!
I believe a complete definition should encompass the following concepts:
mutations
copy number variation (CNV)
codon usage
chromosome numbers
phenotypic change (whether heritable or not)
Complex phenotypic trait such as plasticity and developmental noise
maybe some other things...
My questions are:
Would it be worth it to talk about phenotype in a definition of evolution?
What are the alternative definitions that have been proposed?
What is your definition?
Note: I would rather talk about genetic evolution, but if you think it is worth making one definition for genetic and cultural (and some other stuff maybe) evolution, you're free to suggest it! What is evolution?
In a non-biological sense, evolution means change:
"a process of [...] change"
Biological evolution (seeing as this is Biology stack exchange) then needs to be tweaked to give a biologically specific context. Many textbooks etc. give definitions of evolution and here are a few good ones from across the history of evolutionary biology:
Charles Darwin:
"Descent with modification".
Mark Ridley1:
"Evolution means change, change in the form and behaviour of organisms between generations. ... When members of a population breed and produce the next generation we can imagine a lineage of populations, made up of a series of populations through time. Each population is ancestral to the descendant population in the next generation: a lineage is an ancestor-descendent series of populations. Evolution is then change between generations within a population lineage."
Brian and Deborah Charlesworth2:
"Evolution means cumulative change over time in the characteristics of a population of living organisms. ... All evolutionary changes require initially rare genetic variants to spread among the members of a population, rising to high frequency..."
All of these have a common theme. Biological information is moving through time, descending with a degree of directionality (e.g. parent $\rightarrow$ offspring), and the information is modified with time.
Personally I would define evolution as:
The following is multiple choice question (with options) to answer.
What did darwin call the evolutionary concept of change in populations over generations? | [
"descent with modifications",
"formation with modifications",
"metabolism with modifications",
"reproduction with modifications"
] | A | Wallace and Darwin both observed similar patterns in other organisms and independently conceived a mechanism to explain how and why such changes could take place. Darwin called this mechanism natural selection. Natural selection, Darwin argued, was an inevitable outcome of three principles that operated in nature. First, the characteristics of organisms are inherited, or passed from parent to offspring. Second, more offspring are produced than are able to survive; in other words, resources for survival and reproduction are limited. The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers. Thus, there is a competition for those resources in each generation. Both Darwin and Wallace’s understanding of this principle came from reading an essay by the economist Thomas Malthus, who discussed this principle in relation to human populations. Third, offspring vary among each other in regard to their characteristics and those variations are inherited. Out of these three principles, Darwin and Wallace reasoned that offspring with inherited characteristics that allow them to best compete for limited resources will survive and have more offspring than those individuals with variations that are less able to compete. Because characteristics are inherited, these traits will be better represented in the next generation. This will lead to change in populations over generations in a process that Darwin called “descent with modification. ” Papers by Darwin and Wallace (Figure 11.3) presenting the idea of natural selection were read together in 1858 before the Linnaean Society in London. The following year Darwin’s book, On the Origin of Species, was published, which outlined in considerable detail his arguments for evolution by natural selection. |
SciQ | SciQ-5770 | mountains, geography, paleogeography, isostasy, mountain-building
Title: What were the tallest mountain ranges in Earth's geological past? There have been numerous episodes of mountain building in Earth's geological history, particularly through the super-continent cycle. Many mountains and mountain ranges have been eroded, as mentioned in the similar question Determining the paleoelevation of mountain ranges.
What are believed to be the tallest mountain ranges in Earth's geological past? Additionally, what evidence is there to support these palaeoelevations? Factors determining the maximum possible height of mountains include the rate of uplift versus the rate of erosion[a] and rock strength.
Rock strength is controlled by the type and internal structure of the rock in question. There is some evidence that once mountains extend above the snow line, glacial and periglacial erosion have a stronger control than exhumation/uplift rate (Brozovic et al, 1997; Egholm et al, 2009).
Everest and the Himalaya have reached their maximum possible elevation: the formation of the Tibetan plateau is due to the failure of rocks preventing the maintenance of discrete mountain peaks. The principle of uniformitarianism suggests that - subject to differences in variables discussed by Egholm et al, including crustal composition - the Himalaya and Tibetan plateau are an excellent approximation to the maximum achievable height of mountain ranges. However, identifying which specific palaeoranges were tallest (as opposed to calculating a plausible upper limit on height) is a significantly harder problem to solve.
[a] Though note that the rate of erosion increases as the rate of uplift increases - for more on erosional equilibrium, see e.g. Riebe et al (2000).
The following is multiple choice question (with options) to answer.
Surprisingly, where would you find the earth’s tallest mountains and deepest canyons? | [
"Tibet",
"taiga",
"rain forests",
"ocean floor"
] | D | Scientists have learned a lot about the ocean floor. For example, they know that Earth’s tallest mountains and deepest canyons are on the ocean floor. The major features on the ocean floor are described below. They are also shown in Figure below . |
SciQ | SciQ-5771 | visible-light, scattering, atmospheric-science, sun
It's tricky to figure out what it's a shadow of, but straight lines in the sky like this are almost always shadows of land features.
See this similar photo where the shadows are attributed to a thunderhead, in line with your suggestion about the shadow coming from a cloud.
The following is multiple choice question (with options) to answer.
The part of the shadow in which light is completely blocked is called what? | [
"corona",
"umbra",
"penumbra",
"eclipse"
] | B | The umbra is the part of the shadow in which light is completely blocked. |
SciQ | SciQ-5772 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
What is the name of the period of transition between the beginning of puberty and adulthood? | [
"childhood",
"aging",
"adolescence",
"maturation"
] | C | Adolescence is the period of transition between the beginning of puberty and adulthood. Adolescence is also a time of significant mental, emotional, and social changes. For example:. |
SciQ | SciQ-5773 | physical-chemistry, ionic-compounds
Title: What is Sodium Chloride like in gas state? Since sodium chloride is sodium and chlorine atoms bonded as a lattice and there are no discrete molecules, doesn't that mean in gas state, sodium chloride is simply sodium and chlorine atoms separate from each other, resulting in a mixture of sodium gas and chlorine gas? No, in the gas phase sodium chloride exists as a monomer (the sodium chloride molecule) along with its dimer $\ce{Na2Cl2}$. The dimer has a roughly rectangular shape and is quite floppy with chlorines located diagonally across from each other. The dimer makes up about 27% of the mix. All of the bond lengths, etc. can be found in this thesis. Go to the end and you'll see the full paper that appeared in JACS with all of the data.
Also this paper here (credit to orthocresol for finding that). The abstract mentions "the equilibrium structures of the monomer (NaCl) and the dimer $\ce{Na2Cl2}$"
The following is multiple choice question (with options) to answer.
The formula unit of sodium chloride dissociates into one sodium ion and one? | [
"magnesium ion",
"electron",
"chloride ion",
"oxygen ion"
] | C | The formula unit of sodium chloride dissociates into one sodium ion and one chloride ion. The calcium nitrate formula unit dissociates into one calcium ion and two nitrate ions. This is because of the 2+ charge of the calcium ion. Two nitrate ions, each with a 1− charge are required to make the equation balance electrically. The ammonium phosphate formula unit dissociates into three ammonium ions and one phosphate ion. Note that the polyatomic ions themselves do not dissociate further, but remain intact. |
SciQ | SciQ-5774 | Therefore, the roots are: . $-3,\:-1,\:1,\:3$
• Oct 28th 2006, 10:58 PM
fima2001
i ment
there will be 4 answers and the subtraction of each 2 close
roots will be the same resolt
The following is multiple choice question (with options) to answer.
Fibrous root systems have many small branching roots called what? | [
"fibrous roots",
"tendrils",
"taproots",
"vines"
] | A | Fibrous root systems have many small branching roots, called fibrous roots , but no large primary root. The huge number of threadlike roots increases the surface area for absorption of water and minerals, but fibrous roots anchor the plant less securely. |
SciQ | SciQ-5775 | human-biology, digestive-system, immune-system, microbiome
All of these immune cells also respond to diffused chemical signals called cytokines. These molecules are secreted by some cells and are received by receptors on the host cells. Sometimes the secretion is by another immune cell, sometimes it is from a non-immune system host cell, and sometimes these molecules can be secreted by the bacteria, fungi, or worms themselves.
Depending on the chemical signals that are secreted, and how the cells are interacting at the time of the message, and which cells are receiving the message, will determine the response to the message. It is contextual. Think of the phrase "You're killing me." If someone says it, while laughing, to a good friend who is telling jokes, it means one thing. If it is screamed as someone is being choked by an attacker, it means something very different.
To summarize, the immune cells are surveilling the environment and trying to pick up what is friend and what is foe and they try to respond accordingly.
Over time and coevolution, our microbiomes have developed ways of communicating with our immune system to let it know that these microbes do not mean any harm. They are able to "train" the immune cells using chemical signaling to temper the immune systems response to them (15), and this is how they are able to coexist within our body and with an immune system that is constantly on seek an destroy missions. Also because of the mucus, our microbiome usually isn't in direct contact with our cells, so it is a different kind of interaction than if an infecting pathogen were to breech the barriers and gain access to sterile areas where no bacteria or fungi should be found, and as a result, the immune system reacts differently.
The following is multiple choice question (with options) to answer.
A system of glands secretes what chemical messenger molecules into the blood? | [
"metabolytes",
"hormones",
"acids",
"enzymes"
] | B | system of glands that secrete chemical messenger molecules called hormones into the blood. |
SciQ | SciQ-5776 | 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.
In eukaryotic cells, molecules such as enzymes are usually compartmentalized into different what? | [
"organisms",
"organelles",
"electrons",
"atoms"
] | B | Enzyme Compartmentalization In eukaryotic cells, molecules such as enzymes are usually compartmentalized into different organelles. This allows for yet another level of regulation of enzyme activity. Enzymes required only for certain cellular processes can be housed separately along with their substrates, allowing for more efficient chemical reactions. Examples of this sort of enzyme regulation based on location and proximity include the enzymes involved in the latter stages of cellular respiration, which take place exclusively in the mitochondria, and the enzymes involved in the digestion of cellular debris and foreign materials, located within lysosomes. Feedback Inhibition in Metabolic Pathways Molecules can regulate enzyme function in many ways. A major question remains, however: What are these molecules and where do they come from? Some are cofactors and coenzymes, ions, and organic molecules, as you’ve learned. What other molecules in the cell provide enzymatic regulation, such as allosteric modulation, and competitive and noncompetitive inhibition? The answer is that a wide variety of molecules can perform these roles. Some of these molecules include pharmaceutical and non-pharmaceutical drugs, toxins, and poisons from the environment. Perhaps the most relevant sources of enzyme regulatory molecules, with respect to cellular metabolism, are the products of the cellular metabolic reactions themselves. In a most efficient and elegant way, cells have evolved to use the products of their own reactions for feedback inhibition of enzyme activity. Feedback inhibition involves the use of a reaction product to regulate its own further production (Figure 6.21). The cell responds to the abundance of specific products by slowing down production during anabolic or catabolic reactions. Such reaction products may inhibit the enzymes that catalyzed their production through the mechanisms described above. |
SciQ | SciQ-5777 | redox
Title: Frost diagram and acidic/basic conditions. The Frost diagram for sulfur shows the relative stability (in terms of cell potentials) of the possible aqueous oxidation states. What is the reason for the instability of higher oxidation states in the acidic regime and their stability in the basic regime ? Something I have always noticed but never been able to apply chemical intuition to. Write out the half-reactions and you will see that oxidation of S almost always creates lots of protons. So you can think of Le Chatelier's principle: if there are already lots of protons around, it will be harder to create more of them. Here's the example for complete oxidation of sulfide to sulfate at pH ~7:
$$\ce{HS- + 4 H2O -> 8e- + 9H+ + SO4^{-2} }$$
Conversely, under alkaline conditions, the equilibrium favors the products even more, because of the "removal" of the protons by the alkaline conditions.
The following is multiple choice question (with options) to answer.
What does the stable form of sulfur at room temperature contain? | [
"eight-membered rings",
"four - membered rings",
"six - membered rings",
"electron shell"
] | A | Larger amounts of sulfur also come from hydrogen sulfide recovered during the purification of natural gas. Sulfur exists in several allotropic forms. The stable form at room temperature contains eight-membered rings, and so the true formula is S8. However, chemists commonly use S to simplify the coefficients in chemical equations; we will follow this practice in this book. |
SciQ | SciQ-5778 | solutions
Title: Can the total amount of solution be found as a ratio between molar mass of a component and total mass of solution? I wonder whether the following relation is true:
$$n_\mathrm{solvent} + n_\mathrm{solute} = \frac{M}{m_\mathrm{solvent} + m_\mathrm{solute}},$$
where $M$ is the molar mass of the component, $n$ is the amount of substance and $m$ is the mass.
It was derived assuming $n = m/M,$ $n = n_\mathrm{solvent} + n_\mathrm{solute}$ and $m = m_\mathrm{solvent} + m_\mathrm{solute}.$
I don't think this is true, but I wanted to be sure before doing anything weird on a test. To sum up the comments, only the following relation for the total amount of solution $n_\mathrm{tot}$ is universally true:
$$n_\mathrm{tot} = n_\mathrm{solvent} + n_\mathrm{solute} = \frac{m_\mathrm{solvent}}{M_\mathrm{solvent}} + \frac{m_\mathrm{solute}}{M_\mathrm{solute}}\tag{1}$$
The best you can do is to assume that $n_\mathrm{tot}\approx n_\mathrm{solvent}$ for the diluted solutions of small molecules. Also, if the molar masses are similar $(M_\mathrm{solvent}\approx M_\mathrm{solute}\approx \bar{M}),$ the expression can be lead to a common denominator:
$$n_\mathrm{tot} \approx \frac{m_\mathrm{solvent} + m_\mathrm{solute}}{\bar{M}}\tag{2}$$
The following is multiple choice question (with options) to answer.
What term means the amount of a substance required to form a saturated solution in a given amount of solvent at a specified temperature? | [
"turbidity",
"viscosity",
"concentration",
"solubility"
] | D | The solubility of a substance is the amount of that substance that is required to form a saturated solution in a given amount of solvent at a specified temperature. Solubility is often measured as the grams of solute per 100 g of solvent. The solubility of sodium chloride in water is 36.0 g per 100 g water at 20°C. The temperature must be specified because solubility varies with temperature. For gases, the pressure must also be specified. Solubility is specific for a particular solvent. We will consider solubility of material in water as solvent. |
SciQ | SciQ-5779 | human-anatomy, language
Title: Why are we using upper teeth and lower lip on labiodental sounds? I came to wonder this when studying language (as well as other same theme question posted just few ago). For example the word "fantastic" we use upper teeth and lower lip to produce F sound, instead of using lower teeth and upper lip, which would work as well with a small practice. The alternative articulation, called dentolabial, is more difficult to articulate, so it is very rarely used in human language. However, it apparently is common enough in disordered speech to be allocated an ExtIPA diacritic.
The reason labiodentals are easier: Humans normally have a slight overbite.
When the jaw and lips are in a "neutral" position, the lower lip is close to or touching the upper teeth, so with a small vertical movement of the jaw (together with tensing the lip) one can articulate a labiodental. Articulating a dentolabial requires moving the jaw a fair distance forward, to go around the upper teeth before reaching the upper lip. As Ben pointed out in the comments, front-back jaw movement is unusual, a less "common movement in terms of other vocalisations and eating".
Furthermore, since labial articulations are directly visible to observers, learners are especially likely to imitate others' exact articulation. Thus even though labiodentals and dentolabials sound similar, everyone in the population of speakers uses the same articulation (rather than having both articulations in free variation).
Perhaps dentolabials would instead be more common if most people were like this:
The following is multiple choice question (with options) to answer.
What bone forms the upper jaw and supports the upper teeth? | [
"maxillary bone",
"orbital bone",
"tibular bone",
"subaerial bone"
] | A | Figure 7.14 Maxillary Bone The maxillary bone forms the upper jaw and supports the upper teeth. Each maxilla also forms the lateral floor of each orbit and the majority of the hard palate. |
SciQ | SciQ-5780 | phase, temperature
Title: Why does the distance between molecules increase when the temperature is raised? I have learnt that when we heat ice-like substances it changes to water and when I asked my teacher she said that the distance between molecules increases.
When I thought about it a bit more a question arose: Why does the distance between the molecule increase as we raise the temperature? The answer "the distance between molecules increase" is incomplete if not plain wrong.
Temperature is an effect of energy present. Basically, it's an effect of little movements and vibrations of molecules and atoms due to their energy.
In an crystal, the energy of the molecules is so low, that they don't vibrate and move enough to break the structure. The more energy you put into the system, the more the molecules move. At one point, the movement is too much to keep the molecules in place, the crystal structure breaks apart, the ice melts.
A liquid (NOT WATER, IT IS A SPECIAL CASE) has lower density than the crystal because the molecules are moving around a lot and "need more space".
The following is multiple choice question (with options) to answer.
What does increasing a solute's temperature do? | [
"increases its viscosity",
"decrease its solubility",
"no change",
"increases its solubility"
] | D | If a solute is a solid or liquid, increasing the temperature increases its solubility. For example, more sugar can dissolve in hot water than in cold water. |
SciQ | SciQ-5781 | muscles, lungs, human-physiology
Title: Why is there smooth muscle in our bronchioles? Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just remain open? There are at least two things to consider.
First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good enough source of that)
Secondly, you are incorrect in assuming that normal state is "dilated". Dilation of branchioles is sympathetic ("fight-and-fly") response of the nervous system to something like danger, that requires short-term boost in energy production. That is, by default, your airflow is limited. Probably, to limit amount of energy you effectively burn via oxygenation. But most importantly, you leave yourself a reserve in terms of oxygen supply for critical moments.
Some more information you might find here.
The following is multiple choice question (with options) to answer.
What are the pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi? | [
"stomachs",
"kidneys",
"ovaries",
"lungs"
] | D | Gross Anatomy of the Lungs The lungs are pyramid-shaped, paired organs that are connected to the trachea by the right and left bronchi; on the inferior surface, the lungs are bordered by the diaphragm. The diaphragm is the flat, dome-shaped muscle located at the base of the lungs and thoracic cavity. The lungs are enclosed by the pleurae, which are attached to the mediastinum. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. The cardiac notch is an indentation on the surface of the left lung, and it allows space for the heart (Figure 22.13). The apex of the lung is the superior region, whereas the base is the opposite region near the diaphragm. The costal surface of the lung borders the ribs. The mediastinal surface faces the midline. |
SciQ | SciQ-5782 | zoology, data, information
Title: Estimating the diameter of all earths biomass as a sphere I am working on an educational resource about the relative scales of resources compared to the earth. Attached is an example of the earth compared to various elements contained within, as well as a comparison of the sum of all water and the atmospheric gasses (at standard temperature and pressure).
Such images are great for creating a sense of scale and displaying the fragility if earth's ecosystems.
I want to also include spheres of wet biomass, which I would imagine to be quite small.
However, when I do math I am faced with spheres that seem too small.
I did the math based on 3 methods and got answers of 6km to 14km diameter, based on Metric Ton estimates of 1.57E+12, 1.38E+11, 1.00E+12
Two folks on Quora estimate 10km diameter.
My questions are these:
The following is multiple choice question (with options) to answer.
The global biosphere includes all areas of what? | [
"geography",
"life",
"study",
"science"
] | B | The global biosphere, which includes all areas that contain life, from the sea to the atmosphere. |
SciQ | SciQ-5783 | quantum-mechanics, electrons, atoms
Title: Do orbitals overlap? Yes, as the title states: Do orbitals overlap ?
I mean, if I take a look at this figure...
I see the distribution in different orbitals. So if for example I take the S orbitals, they are all just a sphere. So wont the 2S orbital overlap with the 1S overlap, making the electrons in each orbital "meet" at some point?
Or have I misunderstood something? If you mean to ask "do the orbital radial probability distributions overlap?", the answer is yes:
Image Credit
making the electrons in each orbital "meet" at some point
As you can see from the image, the electron orbitals are not position eigentstates. If you're imagining two point-like electrons in different orbitals colliding, you're not thinking "quantum mechanically".
The following is multiple choice question (with options) to answer.
Atomic orbitals from different atoms overlap to form what? | [
"space orbitals",
"planet orbitals",
"molecular orbitals",
"plasma orbitals"
] | C | Atomic orbitals from different atoms overlap to form molecular orbitals. |
SciQ | SciQ-5784 | toxicity
Cigarette smoke is a complex and dynamic aerosol consisting of at least 5,600 chemicals and toxicants found across two phases, the particulate (tar) and vapour phase.
(I would like to add the gas phase...) so when the product of the combustion of the tobacco are in this physical state you have to look at a different method of administration in this case vapour inhalation, Dust and Mist Inhalation and gas inhalation these are the most potentially dangerous method of administration. It seems that after about 40 minutes the liquid and solid part of the aerosol deposit (of course this depends on the condition, T, wind etc. etc.) so is probable that after this period of time the toxicity of tobacco combustion products decrease considerably. However this is not true for all the combustion products. For example: carbon monoxide is recognize tobacco combustion product and it is a gas so it wont deposit after this time and it will be "removed by reactions with OH radicals (85%), by soils (10%), and by diffusion into the stratosphere" very slowly.
Benzene is a good example of how the toxicity depends on the method of administration. LC50 inhalation value of benzene is 10000 ppm TFLo Dermal is 0.92 mL/kg so it is a big difference if you wait that the areosol deposit or if you inhale it.
If you are interested in rate of decomposition of benzene it seems that biodegradation of benzene can reach 0.95% at day according to Chiang.
Regarding 1-3 butadiene according to William A. McClenny and Donald Whitaker:
i.e., a 10-6 lifetime risk level for cancer due to inhalation exposure
of 0.03 $g/m^{3}$ (12.4 pptv at 20 °C and 1 atm pressure).1 This compound
is very reactive in the ambient atmosphere with a short
atmosphericlifetime, estimated to be 2–3 hr.
The half-life of acrolein is 14.4 hr.
You can also find a very complete EPA report EPA/600/P-98/001F
October 2002.
However determine the half-life of all the compounds is a very complex task because is related to how the ecosystem respond to these compounds so to the actual capability to decompose them through different mechanism is strictly related with thousands of factors.
The following is multiple choice question (with options) to answer.
Particulates cause lung diseases. they can also increase the risk of heart disease and the number of what? | [
"cancer",
"shortness of breath",
"asthma attacks",
"coughing"
] | C | Particulates cause lung diseases. They can also increase the risk of heart disease and the number of asthma attacks. Particulates block sunlight from reaching Earth’s surface. This means there is less energy for photosynthesis. Less photosynthesis means that plants and phytoplankton produce less food. This affects whole ecosystems. |
SciQ | SciQ-5785 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
What reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction? | [
"pores valve",
"moderator band",
"moderator valve",
"pores band"
] | B | The walls of the ventricle are lined with trabeculae carneae, ridges of cardiac muscle covered by endocardium. In addition to these muscular ridges, a band of cardiac muscle, also covered by endocardium, known as the moderator band (see Figure 19.9) reinforces the thin walls of the right ventricle and plays a crucial role in cardiac conduction. It arises from the inferior portion of the interventricular septum and crosses the interior space of the right ventricle to connect with the inferior papillary muscle. When the right ventricle contracts, it ejects blood into the pulmonary trunk, which branches into the left and right pulmonary arteries that carry it to each lung. The superior surface of the right ventricle begins to taper as it approaches the pulmonary trunk. At the base of the pulmonary trunk is the pulmonary semilunar valve that prevents backflow from the pulmonary trunk. |
SciQ | SciQ-5786 | dna, zoology, radiation, entomology
1.-3. Therefore, the only sensitive part of insects is the intestinal epithelium which gets renewed on a regular basis (similar to that of humans, also a known target of radiation), but...
Insects (and generally the arthropodes) are known to have exoskeleton. This potentially serves as a good "armor" for vulnerable intestine cells, filtering out the most heavy particles (like alpha- and in some respect also the beta-particles).
EDIT: This seems not to be real protection, see the discussion in comments.
Therefore it is not a surprise that insects generally show much higher resistance against radiation.
EDIT:
As it was correctly added in the comments, there are also gamets, that are most sensitive to radiation (because they bear only the half of the normal genetic information and cannot repair mutations). Even though the lesions in gamets do not lead to immediate death, the potential sterility can easily cause the extinction.
However, cockroaches (and insects generally) are known to be r-animals, meaning that they favor the quantity (r) over quality (K) of their off-spring. This strategy is optimal when dealing with radiation-induced changes in gametes: the high number of offsprings compensates for the genetic imperfections in gametes.
[a] -- meaning that is has secreted peptides in their hemolymph that protect them
[b] -- there are phagocytes, somewhat similar to tissue magrophages in humans, but the rest of the cell chains in immune response in vertrebrates, like T- and B-cells, are completely missing. Those are responsible for the mediation and amplification of the immune response in vertebrates and are the cells that are most susceptible to radiation damage.
The following is multiple choice question (with options) to answer.
What kind of radiation is observed in honeycreeper birds? | [
"spontaneous",
"adaptive",
"symbiotic",
"destructive"
] | B | Figure 18.13 The honeycreeper birds illustrate adaptive radiation. From one original species of bird, multiple others evolved, each with its own distinctive characteristics. |
SciQ | SciQ-5787 | observational-astronomy, radio-astronomy, radio-telescope, radar
X and Ka band uplink antenna array technology. With the support of the national high-tech development plan, China has also made breakthroughs in the research of uplink antenna array technology, and successfully achieved the C-band communication satellites in geosynchronous geostationary orbit. (Transmit frequency 6 GHz) 3 antenna uplink array technology verification, achieved 80% synthesis efficiency. The follow-up need for higher frequency X and Ka band uplink antenna array, focus on accurate estimation of uplink phase delay changes Research on precise control technology of technology, time delay and phase alignment and large loop system calibration technology.
Rather than build one giant dish for transmitting like Goldstone Solar System Radar which is
...a large radar system used for investigating objects in the Solar system. Located in the desert near Barstow, California, it comprises a 500-kW X-band (8500 MHz) transmitter and a low-noise receiver on the 70-m DSS 14 antenna at the Goldstone Deep Space Communications Complex. It has been used to investigate Mercury, Venus, Mars, the asteroids, and moons of Jupiter and Saturn. The most comparable facility was the radar at Arecibo Observatory, until that facility collapsed. GSSR now stands alone.
...they will use several 35 m transmitting dishes and an even larger number and more widely separated array of receiving dishes.
Table 7, "China asteroid detection multi-bases radar system layout station composition" is a list of transmitting sites. Obviously not all can be coherent and they will be used in a variety of ways.
The following is multiple choice question (with options) to answer.
What do we call the worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations? | [
"compass",
"gps",
"cellular network",
"radio waves"
] | B | You must have a GPS receiver to use the system. You can buy many types of these in stores. The GPS receiver detects radio signals from nearby GPS satellites. There are precise clocks on each satellite and in the receiver. The receiver measures the time for radio signals from satellites to reach it. The receiver uses the time and the speed of radio signals to calculate the distance between the receiver and the satellite. The receiver does this with at least four different satellites to locate its position on the Earth’s surface ( Figure above ). GPS receivers are now being built into many items, such as cell phones and cars. |
SciQ | SciQ-5788 | inorganic-chemistry, solubility, analytical-chemistry
Title: Solubility and wetting of substances in water We have seen that, when we pour salt in water then it gets dissolved, that means it is soluble in water. But when we pour sand into water then it doesn't dissolve in water, that means it is insoluble, but still sand gets wet. But there are certain substances which doesn't get wet by water for example, sulfur particles don't get wet by water but wet in oil, as I was studying about froth floatation method.
My question is that:
What is the difference between solubility and wetting in water ?
What is the reason that the sulfur particle doesn't get wet by water? Polar/hydrophilic soluble substances get dissolved, like table salt or sugar.
Polar/hydrophilic insoluble substances get wet, as they attract water, like sand, or limestone.
Nonpolar/hydrophobic insoluble substances do not get wet, as they repulse water, like wax, teflon or silanized glass.
The following is multiple choice question (with options) to answer.
What substance can be eroded by wind or water? | [
"soil",
"wood",
"sand",
"metal"
] | A | Soil and water are renewable resources but may be ruined by careless human actions. Soil can be depleted of nutrients. It can also be eroded by wind or water. |
SciQ | SciQ-5789 | biochemistry, neuroscience, brain, neuroanatomy
Title: The human brain in numbers I: neurons Even though knowing the number of neurons in a functional unit or with the same function is not of main importance, it may be interesting to know their orders of magnitude, especially in the human brain. For example:
|------------------|------------------|
| cerebellum | 100,000,000,000 |
| cortex | 20,000,000,000 |
| telencephalon | 10,000,000,000 |
| brainstem | 1,000,000,000 |
| sensory neurons | |
| haptic | 500,000,000 |
| visual | 100,000,000 |
| auditory | 2,000 |
| limbic system | |
| amygdala | 10,000,000 |
|------------------|------------------|
The following is multiple choice question (with options) to answer.
What unit of the nervous system consists of a cell body, dendrites, and axon? | [
"neuron",
"ganglion",
"mitochondria",
"Transmitter"
] | A | Neurons are the structural and functional units of the nervous system. They consist of a cell body, dendrites, and axon. |
SciQ | SciQ-5790 | planet, natural-satellites, nomenclature
Title: Is the satellite of a small star in a binary solar system a moon or a planet? What exaclty distinguishes a moon from a planet?
In a binary solar system that has a large star in the center and a smaller star - among some planets - orbiting that large star, and the smaller star has natural satellites - are these satellites called moons or planets?
Or asked in a different way - if Jupiter would ignite and become a star (which it can't because its mass doesn't suffice, but let's assume it was larger and could ignite), would its moons then be considered planets? A planetary mass object (also callled a planemo) is an astronomical object large enough to be pulled into a roughly spherical shape by its gravity compressing its matter. A planetary mass object must also have less than about 13 times the mass of Jupiter or about 4,131.4 times the mass of Earth.
If a planetary mass object orbits around the Sun in our solar system it is called a planet (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, & Neptune) or a dwarf planet (Ceres, Pluto, Eris, Hamaea, and Makemake, plus of number of candidate objects).
If a planetary mass object orbits around a planet in our solar system it is considered to be a natural satellite or a moon. Smaller objects which orbit around planets are also considered to be moons.
Any object smaller than a planetary mass object that orbits the Sun in our solar system is a small solar system body. They include all comets, asteroids, etc. that orbit the Sun ddirectly instead of orbiting one of the planets, moons, asteroids etc. that orbit the sun.
Any astronomical body with a mass greater than about 75 times the mass of Jupiter, or about 23,835 times the mass of the Earth, is a star are the stellar remnant of a star which has completed its "life cycle".
Any planetary mass object which directly orbits a star which is not the Sun, in another star system, is usually considered to be planet. So far there has been no effort to classify exoplanets (planets orbiting other stars) in other star systems as planets or dwarf planets. If they are large enough to be detected they are considered to be explanets. That might possibly change sometime in the future.
The following is multiple choice question (with options) to answer.
What are small planets in our solar system called? | [
"scrub planets",
"dwarf planets",
"Tiny planets",
"light planets"
] | B | Eris is the largest known dwarf planet in the solar system. It is 27 percent larger than Pluto ( Figure above ). Like Pluto and Makemake, Eris is in the Kuiper belt. But Eris is about 3 times farther from the Sun than Pluto. Because of its distance, Eris was not discovered until 2005. Early on, it was thought that Eris might be the tenth planet. Its discovery helped astronomers realize that they needed a new definition of “planet. ” Eris has a small moon, Dysnomia. Its moon orbits Eris once about every 16 days. |
SciQ | SciQ-5791 | quantum-mechanics, condensed-matter, solid-state-physics
Title: Highest occupied orbitals or bands I am not a student of physics, but a student of nano-technology, hence I might sound extremely stupid, but I just want to clarify my doubt even if sounds very trivial.
The no. of free charge carriers, $n$, around an energy $E_{0}$ could be given as
$$n=\int_{E_{0}-\Delta/2}^{E_{0}+\Delta/2}\rho\left(E\right)f(E)\,\mathrm{d}E$$
where $\rho(E)$ is the density of states and $f(E)$ is the Fermi distribution. Now, because of the shape of the Fermi distribution, I would assume that using the integral below, $n$ would be zero only at $E_0=\infty$, and hence at finite temperatures, no state $E_0$ would be completely filled or completely empty and have a non-zero probability distribution value $f(E)\rho(E)$ of being occupied. But at $T=0K$, the story is different, since the fermi distribution becomes a kind of step. Does that mean that at finite temperatures, we cannot logically assign a highest filled orbital and that the concept of Highest or lowest occupied states exist only in context of the zero kelvin story?? As you already said the definition of the highest occupied level does indeed only really exist for T = 0K. For finite temperatures the term of "highest occupation" is still used but what is actually referred to is the position of the Fermi energy, which is mostly defined as the energy where the Fermi-distribution has the value 1/2.
The following is multiple choice question (with options) to answer.
What is electrons in the highest occupied principal energy level of an atom called? | [
"shell electrons",
"gradient electrons",
"valence electrons",
"non-valence electrons"
] | C | In the study of chemical reactivity, we will find that the electrons in the outermost principal energy level are very important and so they are given a special name. Valence electrons are the electrons in the highest occupied principal energy level of an atom. In the second period elements listed above, the two electrons in the 1 s sublevel are called inner-shell electrons and are not involved directly in the element’s reactivity or in the formation of compounds. Lithium has a single electron in the second principal energy level and so we say that lithium has one valence electron. Beryllium has two valence electrons. How many valence electrons does boron have? You must recognize that the second principal energy level consists of both the 2 s and the 2 p sublevels and so the answer is three. In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in s 2 p 6 , has eight valence electrons. |
SciQ | SciQ-5792 | mitochondria, energy-metabolism
Myofibrils are formed of many myofilaments (actin and myosin) organized into contractile (motor) units known as sarcomeres.
Muscles contract when a threshold electrical stimulus depolarises the sarcolemma resulting in an action potential that propagates to T-tubules. At the T-tubules, the reversal of relative charge accross the membrane changes the shape of dihydropyridine receptors so they now allow for the influx of $\ce{Ca^{2+}}$. Consequently, ryanodine receptors on the terminal cisternae of sarcoendoplasmic reticula open and more $\ce{Ca^{2+}}$ diffuse into the sarcoplasm ($\ce{Ca^{2+}}$-induced $\ce{Ca^{2+}}$ release). This increases sarcoplasmic $\ce{Ca^{2+}}$ concentration. $\ce{Ca^{2+}}$ binds to troponin which changes shape. Since troponin is bound to tropomyosin, changing the shape of the former displaces the latter. Tropomyosin consequently exposes myosin-binding sites on actin so myosin can now bind, bend, detach and get back to original conformation to repeat the process (cross-bridge cycling) until $\ce{Ca^{2+}}$ is actively pumped back to where it came from causing tropomyosin to block active sites and relaxation. The magnitude of the response of the muscle to stimulation (whether acetylcholine or depolarisation can elicit an action potential) depends on
strength of the stimulus (amount of acetylcholine or change in membrane potential).
duration of the stimulus (time for which acetylcholine or charge persist).
frequency of stimulation or rise of stimulus intensity (since acetylcholine and charge accumulate).
Muscle fatigue as we know it can be attributed to different mechanisms that happen at different stations.
Neural (central) fatigue
Metabolic (peripheral) fatigue
The following is multiple choice question (with options) to answer.
Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a what? | [
"adipocytes",
"coenocyte",
"syncytium",
"tapetum"
] | C | 10.7 Cardiac Muscle Tissue Cardiac muscle is striated muscle that is present only in the heart. Cardiac muscle fibers have a single nucleus, are branched, and joined to one another by intercalated discs that contain gap junctions for depolarization between cells and desmosomes to hold the fibers together when the heart contracts. Contraction in each cardiac muscle fiber is triggered by Ca++ ions in a similar manner as skeletal muscle, but here the Ca++ ions come from SR and through voltage-gated calcium channels in the sarcolemma. Pacemaker cells stimulate the spontaneous contraction of cardiac muscle as a functional unit, called a syncytium. |
SciQ | SciQ-5793 | crystal-structure
Title: Why shape of diamond is like diamond? I know that in diamond carbon atoms occur in 3d geometry but i want to ask that why it is in shape of diamond not like some other 3d geometrical shape like cube or cuboid? Diamond has the shape of diamond for precisely the same reason why any other crystal has the shape it has. Some crystal faces have lower surface energy than others, so the crystal grows in these directions, as if it wanted to develop these faces and avoid developing others.
This, BTW, is not determined by crystal family alone. Think of pyrite: it also has cubic unit cell, but it mostly develops the face (001) (see Miller indices) and hence makes those nice cubic crystals. On the contrary, diamond prefers the face (111), which together with its symmetry equivalents produces an octahedron. And that's why natural diamonds are typically found in this shape (not counting scratches and fractures).
Because of its low energy, the (111) face is also the hardest face of a diamond, to the point that jewelers deliberately avoid it when cutting brilliants, for it can't be polished quite as good as any other arbitrary plane.
So it goes.
The following is multiple choice question (with options) to answer.
A mineral’s crystal shape is determined by the way what objects are arranged? | [
"particles",
"atoms",
"Electrons",
"molecules"
] | B | The patterns of atoms that make a mineral affect its physical properties. A mineral’s crystal shape is determined by the way the atoms are arranged. For example, you can see how atoms are arranged in halite in Figure above . You can see how salt crystals look under a microscope in Figure below . Salt crystals are all cubes whether they're small or large. |
SciQ | SciQ-5794 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
Unlike prokaryotes, eukaryotes have a what? | [
"cell nucleus",
"flagellum",
"mitochondria",
"cell wall"
] | A | Eukaryotes evolved about 2 billion years ago. Unlike prokaryotes, eukaryotes have a cell nucleus. They have more structures and are better organized. Organelles within a eukaryote can perform certain functions. Some supply energy; some break down wastes. Eukaryotes were better able to live and so became the dominant life form. You can see an example of a eukaryotic cell below ( Figure below ). |
SciQ | SciQ-5795 | evolution
Title: How to define "evolution"? The standard answer found in intro course to evolutionary biology to the question:
what is evolution?
is:
It is a change in allele frequency over time!
I believe a complete definition should encompass the following concepts:
mutations
copy number variation (CNV)
codon usage
chromosome numbers
phenotypic change (whether heritable or not)
Complex phenotypic trait such as plasticity and developmental noise
maybe some other things...
My questions are:
Would it be worth it to talk about phenotype in a definition of evolution?
What are the alternative definitions that have been proposed?
What is your definition?
Note: I would rather talk about genetic evolution, but if you think it is worth making one definition for genetic and cultural (and some other stuff maybe) evolution, you're free to suggest it! What is evolution?
In a non-biological sense, evolution means change:
"a process of [...] change"
Biological evolution (seeing as this is Biology stack exchange) then needs to be tweaked to give a biologically specific context. Many textbooks etc. give definitions of evolution and here are a few good ones from across the history of evolutionary biology:
Charles Darwin:
"Descent with modification".
Mark Ridley1:
"Evolution means change, change in the form and behaviour of organisms between generations. ... When members of a population breed and produce the next generation we can imagine a lineage of populations, made up of a series of populations through time. Each population is ancestral to the descendant population in the next generation: a lineage is an ancestor-descendent series of populations. Evolution is then change between generations within a population lineage."
Brian and Deborah Charlesworth2:
"Evolution means cumulative change over time in the characteristics of a population of living organisms. ... All evolutionary changes require initially rare genetic variants to spread among the members of a population, rising to high frequency..."
All of these have a common theme. Biological information is moving through time, descending with a degree of directionality (e.g. parent $\rightarrow$ offspring), and the information is modified with time.
Personally I would define evolution as:
The following is multiple choice question (with options) to answer.
What term is used to describe major changes in the genetic material? | [
"chromosomal alterations",
"mutational alterations",
"generational alterations",
"eukaryotic alterations"
] | A | Chromosomal Alterations. Chromosomal alterations are major changes in the genetic material. |
SciQ | SciQ-5796 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
What type of rocks form when sediments are compacted and cemented together? | [
"crystalline rocks",
"metamorphic rocks",
"igneous rocks",
"sedimentary rocks"
] | D | Sedimentary rocks form when sediments are compacted and cemented together. Sediments are pieces of rock. They may be gravel, sand, silt, or clay. Some sedimentary rocks form the solid minerals left behind after a liquid evaporates. |
SciQ | SciQ-5797 | condensed-matter
Title: If a liquid is compressed enough, would it become solid? If a liquid were to be compressed so tensely that the particles had no room to move, would it then become a solid?
Also, would the same happen with a gas? It depends on the substance. It is easy to work out though from the relevant phase diagram.
Isothermally increasing the pressure of liquid CO$_2$ will create a solid phase (dry ice). But increasing the pressure of liquid water will not create ice.
A gas-to-solid transition with increasing pressure is a process called deposition. It will happen with most substances if the temperature is sufficiently low.
The following is multiple choice question (with options) to answer.
Processes in which matter changes between liquid and solid states are freezing and? | [
"transpiration",
"steaming",
"boiling",
"melting"
] | D | Processes in which matter changes between liquid and solid states are freezing and melting. |
SciQ | SciQ-5798 | geology, mineralogy, minerals, weathering
To me, supergene has a specific meaning, it may be part of the weathering process in some locations, but weathering involves the breaking down of rocks due to: reactions with atmospheric gasses, water (usually rain), changes brought on by plants, bacteria wind and temperature.
My suggestion to use the term weathering or weathered.
The following is multiple choice question (with options) to answer.
Abrasion is a process of what type of weathering? | [
"mechanical",
"molecular",
"environmental",
"geological"
] | A | Ice wedging and abrasion are two important processes of mechanical weathering. |
SciQ | SciQ-5799 | genetics
Title: Can there be medium height(neither tall nor short) pea plants in Mendel's experiment? Can there be medium height(neither tall nor short) pea plants in Mendel's experiment?
All textbooks I have read seem to imply that pea plants have to be either tall or short, nothing in between. Medium height (like in people) and other traits that seem like a mixture of two extremes are often a result of incomplete dominance. For example, a red and white flower are bred to produce an offspring with pink petals.
Mendelian genetics does not include incomplete dominance (which is classified as, surprisingly, non-Mendelian genetics).
Basically, Mendel got very lucky with his choice of plant. Pea plant height is strictly dominant, meaning one dominant allele results in tall plants, regardless of the identity of the second inherited allele. This is a consequence of the genetic makeup of pea plants. Had he tried a similar experiment with snapdragon flower color, he would be very confused.
(See https://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel2.htm for snapdragon incomplete dominance example.)
The following is multiple choice question (with options) to answer.
Mendel’s observation of pea plants also included many crosses that involved multiple traits, which prompted him to formulate the principle of this? | [
"independent texture",
"independent contain",
"independent assortment",
"dependent evolution"
] | C | Mendel’s observation of pea plants also included many crosses that involved multiple traits, which prompted him to formulate the principle of independent assortment. The law states that the members of one pair of genes (alleles) from a parent will sort independently from other pairs of genes during the formation of gametes. Applied to pea plants, that means that the alleles associated with the different traits of the plant, such as color, height, or seed type, will sort independently of one another. This holds true except when two alleles happen to be located close to one other on the same chromosome. Independent assortment provides for a great degree of diversity in offspring. Mendelian genetics represent the fundamentals of inheritance, but there are two important qualifiers to consider when applying Mendel’s findings to inheritance studies in humans. First, as we’ve already noted, not all genes are inherited in a dominant–recessive pattern. Although all diploid individuals have two alleles for every gene, allele pairs may interact to create several types of inheritance patterns, including incomplete dominance and codominance. Secondly, Mendel performed his studies using thousands of pea plants. He was able to identify a 3:1 phenotypic ratio in second-generation offspring because his large sample size overcame the influence of variability resulting from chance. In contrast, no human couple has ever had thousands of children. If we know that a man and woman are both heterozygous for a recessive genetic disorder, we would predict that one in every four of their children would be affected by the disease. In real life, however, the influence of chance could change that ratio significantly. For example, if a man and a woman are both heterozygous for cystic fibrosis, a recessive genetic disorder that is expressed only when the individual has two defective alleles, we would expect one in four of their children to have cystic fibrosis. However, it is entirely possible for them to have seven children, none of whom is affected, or for them to have two children, both of whom are affected. For each individual child, the presence or absence of a single gene disorder depends on which alleles that child inherits from his or her parents. |
SciQ | SciQ-5800 | species-identification, zoology, marine-biology, ichthyology, bone
Title: Identification of a strange skull My father is a fisherman in the Baltic sea, and he has found this very strange skull. I would like to know to which animal it belonged. Can someone help identify it? Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is indeed a neurocranium.(source of the picture).
Thank you all for your help!
The following is multiple choice question (with options) to answer.
The skull consists of cranial bones and what other type of bones? | [
"superficial",
"subdermal",
"facial",
"nasal"
] | C | The bones of the skull support the structures of the face and protect the brain. The skull consists of cranial bones and facial bones. The cranial bones form the cranial cavity, which encloses the brain and serves as an attachment site for muscles of the head and neck. In the adult they are tightly jointed with connective tissue and adjoining bones do not move. The auditory ossicles of the middle ear transmit sounds from the air as vibrations to the fluid-filled cochlea. The auditory ossicles consist of two malleus (hammer) bones, two incus (anvil) bones, and two stapes (stirrups), one on each side. Facial bones provide cavities for the sense organs (eyes, mouth, and nose), and serve as attachment points for facial muscles. The hyoid bone lies below the mandible in the front of the neck. It acts as a movable base for the tongue and is connected to muscles of the jaw, larynx, and tongue. The mandible forms a joint with the base of the skull. The mandible controls the opening to the mouth and hence, the airway and gut. |
SciQ | SciQ-5801 | zoology, species-identification, entomology
Title: Identification of a segmented black insect in France
Found in the Lot department of southern France. I think this is some sort of soldier fly larva (family Stratiomyidae). That would explain lack of legs. There are thousands of species world wide, with both aquatic and terrestrial larvae, so it might be possible to narrow it down a bit more.
Image from bugguide.net for comparison:
Thanks to @bli for reminding me of dipteran larvae!
The following is multiple choice question (with options) to answer.
Insects are arthropods in which class? | [
"trichina",
"hexapoda",
"xerophyte",
"lexapoda"
] | B | Insects are arthropods in the class Hexapoda. They are the most numerous organisms in the world. Most are terrestrial, and many are aerial. Insects have six legs and a pair of antennae for sensing chemicals. They also have several eyes and specialized mouthparts for feeding. Insects are the only invertebrates that can fly. Flight is the main reason for their success. Insects may live in large colonies and have complex social behaviors. Insects spread disease and destroy crops. However, they are essential for pollinating flowering plants. |
SciQ | SciQ-5802 | marine-biology, vestigial
Title: Modern Whales with Vestigial legs Myth? Is it a myth that modern whales have been found with hind legs sticking out of their sides and full formed tibias, fibias, and toe bones? I keep finding assertions, but no citations. For example, the wikipedia page has no citation for it.
http://en.wikipedia.org/wiki/Whales#Appendages The link you give doesn't mention limbs sticking out of the body wall, but only vestigial hind limb elements. Many whales do retain pelves and femora, as this page at the Bergen Museum shows. Given the variation in limb development across vertebrates, it would not be surprising to find more distal elements (but I would be very surprised if they extended past the body wall).
The following is multiple choice question (with options) to answer.
What is the tail bone an example of? | [
"invertebrate structure",
"vestigial structure",
"primordial structure",
"parasitic structure"
] | B | Some of the most interesting evidence for evolution comes from vestigial structures . These are body parts that are no longer used but are still present in modern organisms. Examples in humans include tail bones and the appendix. |
SciQ | SciQ-5803 | thermodynamics, statistical-mechanics, phase-transition
In this particular question, I am not interested in the critical point but rather an arbitrary position on the coexistence curve; say, the middle inset. In this diagram, Callen seems to be showing that at fixed $T,P,N$, $V$ is variable! But that is of course absurd since there are only 3 DOF.
What I think perhaps is going on is that our system/substance has underlying phases which each have separate nominal fundamental equations (i.e. each phase $i$ has a $G_i(T,P,N)$), but the actual fundamental equation is the minimum over all such phases at the given $T,P,N$ ($G(T,P,N) = \min_i G_i(T,P,N)$). The phase transition happens when we cross over from one $i$ to some other $j$ in this minimum. However, this description does not comport with Callen drawing $V$ as a continuous variable. My picture seems to suggest that there should be discrete points $V_i$ (since $T,P,N$ fix $V_i$ for the given phase) corresponding to the minimums given in the inset.
Since Callen's description in terms of a continuous variable is very much different than mine, it seems I must be missing something? You have hit a point where Callen's explanation of what is going on is not as clear as other parts of his textbook. In Section 9.1, he tries to make the puzzling dependence of the Gibbs free energy on the volume understandable, mentioning fluctuations. Still, there is no explicit argument, and I never found that part convincing.
However, it is possible to give a sound argument based on thermodynamics.
We know that at constant pressure and temperature (and number of molecules), the stable thermodynamic equilibrium corresponds to the absolute minimum of Gibbs' free energy with respect to every variable controlling a possible internal constraint in the system.
The following is multiple choice question (with options) to answer.
What is the intersection point of the critical temperature and the critical pressure called? | [
"basic juncture",
"peak point",
"instance point",
"critical point"
] | D | Refer again to water’s phase diagram ( Figure above ). Notice point E, labeled the critical point . What does that mean? At 373.99°C, particles of water in the gas phase are moving very, very rapidly. At any temperature higher than that, the gas phase cannot be made to liquefy, no matter how much pressure is applied to the gas. The critical pressure (P c ) is the pressure that must be applied to the gas at the critical temperature in order to turn it into a liquid. For water, the critical pressure is very high, 217.75 atm. The critical point is the intersection point of the critical temperature and the critical pressure. |
SciQ | SciQ-5804 | rocketry, nuclear-engineering, nuclear-technology
Title: How does a nuclear powered rocket engine work? Nuclear power always require some way of converting the energy from nuclear to electrical or mechanical to be useful. For example, in a nuclear power generation facility, this is done through heat/steam which drives mechanical generators. What is the mechanism used to convert nuclear energy to rocket power? In Nuclear Thermal Rockets (NTRs)
the heat from a nuclear reaction replaces the chemical energy of the propellants in a chemical rocket. In an NTR, a working fluid, usually liquid hydrogen, is heated to a high temperature in a nuclear reactor and then expands through a rocket nozzle to create thrust. The external nuclear heat source theoretically allows a higher effective exhaust velocity and is expected to double or triple payload capacity compared to chemical propellants that store energy internally.
The following is multiple choice question (with options) to answer.
Nuclear power plants produce electricity through what? | [
"intense fission",
"induced fission",
"High Fission",
"severe fission"
] | B | Nuclear power plants produce electricity through induced fission. |
SciQ | SciQ-5805 | organic-chemistry
Title: What are the minimal chemical requirements for a food which we all can eat? I've been puzzled by the following though experiment for the past few days:
I want to make my own food from scratch, but I do not know where to start from.
I want to be 100% sure that what I eat will never contains something that can damage my body. For example: If you buy something from the local market you can not be 100% sure that it's safe to eat. (99.9 % maybe... but that's not 100%)
I want to ask you to tell me, how can I make a food that I can eat, or should I say - live on it, for the rest of my life, that's 100% safe, I can control every aspect of it's creation and has many combinations of taste because I love diversity.
Thank you for your time : )
Edit:
Because I realized my question is very broad and indeed is a little... too much scientific I want to close it. But before I do so, here's what I had in mind:
I wanted to take some chemical elements, put them in a jar, run some electricity, heat, whatever through it, filter it, do some additional processing and eat it.
I wanted to know if the stomach can take it, because I was going to eat food that's not hard to digest. Considering the three basic biomolecules used by the body are carbohydrates, lipids, and proteins, you would need to consume these three molecules only. Now we can choose three substances.
Glucose, one of the most basic carbohydrates, is needed for ATP production, so that would be a food choice there.
Any oil or butter will provide lipids.
Protein comes from a variety of sources. Meat is typically though of as the best, but nuts are a pretty good source too.
Since nuts satisfy proteins and lipids, I'd say honey roasted peanuts are the most basic food you could live off of, if you replace pure glucose for the honey.
The following is multiple choice question (with options) to answer.
When the body goes into survival mode, it's first priority is to produce enough of which substance for the brain? | [
"insulin",
"blood",
"plasma",
"glucose"
] | D | Starvation When the body is deprived of nourishment for an extended period of time, it goes into “survival mode. ” The first priority for survival is to provide enough glucose or fuel for the brain. The second priority is the conservation of amino acids for proteins. Therefore, the body uses ketones to satisfy the energy needs of the brain and other glucose-dependent organs, and to maintain proteins in the cells (see Figure 24.2). Because glucose levels are very low during starvation, glycolysis will shut off in cells that can use alternative fuels. For example, muscles will switch from using glucose to fatty acids as fuel. |
SciQ | SciQ-5806 | 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 consider the basic building blocks of life? | [
"cells",
"neurons",
"muscles",
"atoms"
] | A | Cells are the basic building blocks of life. They are like tiny factories where virtually all life processes take place. Some living things, like the bacteria in Figure above , consist of just one cell. They are called single-celled organisms. You can see other single-celled organisms in Figure 2.2. Some living things are composed of a few to many trillions of cells. They are called multicellular organisms. Your body is composed of trillions of cells. |
SciQ | SciQ-5807 | optics, refraction
However, this theorem will not tell you how much the ray has deviated from its initial line of travel. Neither will it tell you how much the ray has been attenuated due to absorption in each layer or reflections at the interfaces between layers.
Neither can the theorem tell you whether the ray undergoes total internal reflection at one of the interfaces between layers of material. In that case the ray will emerge from the face which it entered, or a side face if the slab of multi-layer material is not wide enough. To find out if this happens you need to trace the ray through the layers, checking what happens at each boundary.
The following is multiple choice question (with options) to answer.
Which law describes the angle at which the reflected rays leave the surface is equal to the angle at which the incident rays strike the surface? | [
"gravity",
"diffusion",
"velocity",
"reflection"
] | D | One thing is true of both regular and diffuse reflection. The angle at which the reflected rays leave the surface is equal to the angle at which the incident rays strike the surface. This is known as the law of reflection . The law is illustrated in the Figure below and also in this animation: http://www. physicsclassroom. com/mmedia/optics/lr. cfm. |
SciQ | SciQ-5808 | evolution, botany, photosynthesis, speculative, chloroplasts
Title: Why do plants have green leaves and not red? I know plants are green due to chlorophyll.
Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light has more energy than red light.
Is there no alternative to chlorophyll? Or is it something else? Surely it would be even more beneficial for plants to be black instead of red or green, from an energy absorption point of view. And Solar cells are indeed pretty dark.
But, as Rory indicated, higher energy photons will only produce heat. This is because the chemical reactions powered by photosynthesis require only a certain amount of energy, and any excessive amount delivered by higher-energy photons cannot be simply used for another reaction1 but will yield heat. I don't know how much trouble that actually causes, but there is another point:
As explained, what determines the efficiency of solar energy conversion is not the energy per photon, but the amount of photons available. So you should take a look at the sunlight spectrum:
The following is multiple choice question (with options) to answer.
What major pigment in the photosynthetic system is based on a complex molecule and gives plants their green color? | [
"chlorophyll",
"chloroplasm",
"melanin",
"cadmium"
] | A | membrane gradients was known, Mitchell proposed that energy captured through the absorption of light (by phototrophs) or the breakdown of molecules into more stable molecules (by various types of chemotrophs) relied on the same basic (homologous) mechanism, namely the generation of H+ gradients across membranes (the plasma membrane in prokaryotes or the internal membranes of mitochondria or chloroplasts (intracellular organelles, derived from bacteria – see below) in eukaryotes. What makes us think that these processes might have a similar evolutionary root, that they are homologous? Basically, it is the observation that in both light- and chemical-based processes captured energy is transferred through the movement of electrons through a membrane-embedded “electron transport chain”. An electron transport chain involves a series of membrane and associated proteins and a series of reduction-oxidation or redox reactions (see below) during which electrons move from a high energy donor to a lower energy acceptor. Some of the energy difference between the two is used to move H+ ions across a membrane, generating a H+ concentration gradient. Subsequently the thermodynamically favorable movement of H+ down this concentration gradient (across the membrane) is used to drive ATP synthesis, a thermodynamically unfavorable process. ATP synthesis itself involves the rotating ATP synthase. The reaction can be written: H+outside + ADP + Pi ATP + H2O + H+inside, where “inside” and “outside” refer to compartments defined by the membrane containing the electron transport chain and the ATP synthase. Again, this reaction can run backwards. When this occurs, the ATP synthase acts as an ATPase (ATP hydrolase) that can pump H+ (or other molecules) against its concentration gradient. Such pumping ATPases establishes most biologically important molecular gradients across membranes. In such a reaction: ATP + H2O + molecule in low concentration region ADP + Pi + molecule in low concentration region. The most important difference between phototrophs and chemotrophs is how high energy electrons enter the electron transport chain. Oxygenic photosynthesis
Compared to the salt loving archaea Halobium with its purple bacteriorhodopin-rich membranes, photosynthetic cyanobacteria (which are true bacteria), green algae, and higher plants (both eukaryotes) use more complex molecular systems through which to capture and utilize light. In all of these organisms, their photosynthetic systems appear to be homologous, that is derived from a common ancestor, a topic we will return to later in this chapter. For simplicity’s sake we will describe the photosynthetic system of cyanobacterium; the system in eukaryotic algae and plants, while more complex, follows the same basic logic. At this point, we consider only one aspect of this photosynthetic system, known as the oxygenic or non-cyclic system (look to more advanced classes for more details. ) The major pigment in this system, chlorophyll, is based on a complex molecule, a porphyrin (see above) and it is primarily these pigments that give plants their green color. As in the case of retinal, they absorb visible light due to the presence of a conjugated bonding structure (drawn as a series of alternating single and double) carbon-carbon bonds. Chlorophyll is synthesized by a conserved biosynthetic pathway that is also used to synthesize heme, which is found in the hemoglobin of animals and in the cytochromes, within the electron transport chain present in both plants and animals (which. |
SciQ | SciQ-5809 | thermodynamics, enthalpy, entropy
That is, more energy is released by the system than the enthalpy of reaction.
Of course, the extra energy came from heat energy absorbed from the environment as the entropy of the products was greater than that of the reactants by $\Delta S\;.$
The following is multiple choice question (with options) to answer.
If heat is released by the system into the surroundings, a chemical reaction or physical change is called what? | [
"static",
"biochemical",
"endothermic",
"exothermic"
] | D | In the study of thermochemical processes, things are viewed from the point of view of the system. A chemical reaction or physical change is endothermic if heat is absorbed by the system from the surroundings. In the course of an endothermic process, the system gains heat from the surroundings and so the temperature of the surroundings decreases. The quantity of heat for a process is represented by the letter . The sign of for an endothermic process is positive because the system is gaining heat. A chemical reaction or physical change is exothermic if heat is released by the system into the surroundings. Because the surroundings is gaining heat from the system, the temperature of the surroundings increases. The sign of for an exothermic process is negative because the system is losing heat. |
SciQ | SciQ-5810 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
A hydrostatic skeleton is a skeleton formed by a fluid-filled compartment within the body, called what? | [
"coelom",
"clamon",
"endosperm",
"thallus"
] | A | Hydrostatic Skeleton A hydrostatic skeleton is a skeleton formed by a fluid-filled compartment within the body, called the coelom. The organs of the coelom are supported by the aqueous fluid, which also resists external compression. This compartment is under hydrostatic pressure because of the fluid and supports the other organs of the organism. This type of skeletal system is found in soft-bodied animals such as sea anemones, earthworms, Cnidaria, and other invertebrates (Figure 38.2). |
SciQ | SciQ-5811 | zoology, sensation
Title: Can animals that rely heavily on sonar sense colour? Apparently there're species around as rely heavily on sonar to sense the world around them.
E.g. Bat, Dolphin, Whale ...
The humans, and other terrestrial beings in a lighted world are capable of distinguishing colour in varying degrees of acuity. Is this ability to sense colour in our environment applicable to species (terrestrial, avian, and marine) that rely heavily on sonar? Any animal using sound cannot sense color though sonar directly, though these animals are not entirely blind and can probably see colors in the infrared we can't.
Even on the darkest night there is some light around and all bats use this. Old World fruit bats have colour vision, which is useful to them as they are often quite active in daytime, roosting on trees in exposed positions, rather than tucked away in dark crevices like most microbats, which can see only in black-and-white.
Dolphins have additional senses in addition to seeing they can sense electrical fields. So if an animal has its eyes covered, they will seem to be able to do things you would not expect. Its not the same as seeing the color though.
Such animals using sonar can additionally sense density and hardness as well as other material attributes which would cause the acoustic properties of the material as well as movement.
A hard-bodied insect produces a different quality of echo from one with a soft body, so bats can distinguish between some different groups of insects in this way. They can also determine the size of the object.
What's really interesting is that even human beings can experience this unusual sense. Blind people have learned to echolocate by making clicks with their mouth, and there is a movement to teach this skill.
Anyone can try it. In just an hour or two I was able to tell how close I was to a wall, whether the wall was concrete. I couldn't play video games (2:20 on the link) or see colors though.
The following is multiple choice question (with options) to answer.
Sharks are an example of an animal with sharp vision that is nonetheless unable to distinguish what? | [
"contrast",
"shapes",
"depth",
"color"
] | D | |
SciQ | SciQ-5812 | endocrinology, sexuality
Title: why a testosterone pill can't be effective? Why estrogen, progesterone etc. in the contraceptive pills survive the acid environment of the stomach and all the digestive enzymes, while testosterone needs to be injected or spread with a gel on skin?
I have no idea of why this difference in assumption, because I know testosterone and "feminine" hormones have the same steroid based structure...so I can't pick up why testosterone differently from "feminine" hormones can't resist the digestion. As stated in the comments by Eliane B., testosterone can actually be administered orally when an undecanoate ester is attached. The reason regular testosterone cannot be adminstered orally is because it undergoes extensive first pass metabolism (oxidation of the 17b-hydroxyl group to a 17-keto group, catalyzed by 17b-hydroxysteroid dehydrogenase enzymes, which are active in the liver). The undecanoate ester makes the substance lipophilic enough to be transported by the lymphatic system to the circulation after absorption by the intestines. Without the ester it will first reach the liver via the portal vein, thus exposing it to first pass metabolism. Nevertheless, bioavailability of oral testosterone undecanoate is estimated to be less than 10% [1].
Besides that, there are also derivates of testosterone which have a high oral bioavailability. These derivates have an alpha-oriented alkyl group, usually methyl, at position C-17, which retards hepatic metabolism. However, this can lead to hepatotoxicity [2].
https://www.ncbi.nlm.nih.gov/pubmed/3770015 (note, the subjects were women, but in the literature it is assumed that similiar bioavailability is obtained in men)
https://www.ncbi.nlm.nih.gov/pubmed/27372877
The following is multiple choice question (with options) to answer.
What performance-enhancing drugs are synthetic versions of the male sex hormone, testosterone? | [
"anabolic steroids",
"progesterone",
"estrogen",
"catabolic steroids"
] | A | Anabolic Steroids The endocrine system can be exploited for illegal or unethical purposes. A prominent example of this is the use of steroid drugs by professional athletes. Commonly used for performance enhancement, anabolic steroids are synthetic versions of the male sex hormone, testosterone. By boosting natural levels of this hormone, athletes experience increased muscle mass. Synthetic versions of human growth hormone are also used to build muscle mass. The use of performance-enhancing drugs is banned by all major collegiate and professional sports organizations in the United States because they impart an unfair advantage to athletes who take them. In addition, the drugs can cause significant and dangerous side effects. For example, anabolic steroid use can increase cholesterol levels, raise blood pressure, and damage the liver. Altered testosterone levels (both too low or too high) have been implicated in causing structural damage to the heart, and increasing the risk for cardiac arrhythmias, heart attacks, congestive heart failure, and sudden death. Paradoxically, steroids can have a feminizing effect in males, including shriveled testicles and enlarged breast tissue. In females, their use can cause masculinizing effects such as an enlarged clitoris and growth of facial hair. In both sexes, their use can promote increased aggression (commonly known as “roid-rage”), depression, sleep disturbances, severe acne, and infertility. |
SciQ | SciQ-5813 | water, phase, temperature
Title: Why does water evaporate at room temperature? When water temperature reaches $100\ ^\circ \mathrm{C}$, the molecules get so excited that the hydrogen atoms lose the bonds to the oxygen atom and therefore the water starts to become gas. I get that, but at room temperature ($23\ ^\circ \mathrm{C}$), is there no excitation in the atoms or is there? First, I think I should make it clear that when water boils, the bonds in the water molecule linking the hydrogen and oxygen atom are not broken. During boiling, the intermolecular bonds in water are the ones that get broken, that is the bonds that link the water molecules together.
At room temperature, there is evaporation (I wouldn't call it excitation). This is because there are a few molecules of water which can manage to muster enough energy to escape from the large body of molecules and escape into air.
This can be explained through a graph depicting the distribution of speed among water molecules worked out by Maxwell and Boltzmann.
As you can probably see, there are a lot of water molecules with lower kinetic energy than with higher kinetic energy. Those that have the higher kinetic energy are the ones that are able to break through the water surface to become vapour.
Even at low temperatures, there are some water molecules are have enough energy to escape and that's why evaporation in water can occur at any temperature (yes, even if the water is in ice).
When the temperature increases, there are more molecules with higher kinetic energy and thus, more water can evaporate.
The following is multiple choice question (with options) to answer.
What bonds cause water to have a high boiling point, leaving most water on earth in a liquid state rather than in a gaseous state? | [
"hydrogen bonds",
"potassium bonds",
"carbon bonds",
"helium bonds"
] | A | Hydrogen bonds cause water to have a relatively high boiling point of 100°C (212°F). Because of its high boiling point, most water on Earth is in a liquid state rather than in a gaseous state. Water in its liquid state is needed by all living things. Hydrogen bonds also cause water to expand when it freezes. This, in turn, causes ice to have a lower density (mass/volume) than liquid water. The lower density of ice means that it floats on water. For example, in cold climates, ice floats on top of the water in lakes. This allows lake animals such as fish to survive the winter by staying in the water under the ice. |
SciQ | SciQ-5814 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Each root is made of dermal, ground, and what type of tissue? | [
"organic",
"vascular",
"thermal",
"circulatory"
] | B | Each root is made of dermal, ground, and vascular tissues. |
SciQ | SciQ-5815 | 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 velocity of a moving object called? | [
"acceleration",
"stimulation",
"force",
"inclination"
] | A | Acceleration is a measure of the change in velocity of a moving object. It measures the rate at which the change is occurring. It may reflect a change in speed, a change in direction, or both. Like velocity, acceleration is a vector. |
SciQ | SciQ-5816 | cardiology, medicine
Title: What does irregular heartbeat mean in simple language? I bought a blood pressure monitor (A&D UA-851) which has the option to measure irregular heartbeat. I do understand what 'irregular' means, but why do irregular heartbeats happen and what are it's implications short and long term? The normal cardiac cycle is comprised of two distinct phases: the systolic phase in which the heart contracts, ejecting the blood, followed by the the diastolic phase when the cardiac muscle relaxes, refilling the heart with blood.
This cycle is assured by specialised cardiomyocytes (Cardiac muscle cells) that conduct electrical impulses through the heart. When there's interference in this electric activity, the cycle becomes irregular or arrhythmic.
Arrhythmias can be divided by their place of origin:
Atrial (atria are the upper chambers of the heart)
Ventricular (ventricles are lower chambers of the heart)
Junctional (the junction between the two)
Heart blocks (caused by a blockade in the conductivity of the electrical specialised cardiomyocytes)
Some arrhythmias are physiological, such as the Respiratory sinus arrhythmia, a naturally occurring variation in heart rate that occurs during a breathing cycle. Also, in healthy individuals, some extra sistoles might occur without being the translation of a subjacent heart condition and have benign prognosis in individuals without other conditions.
However, some arrhythmias can have a wide range of health implications, from asymptomatic, to a mild intolerance to exercise, to Cerebrovascular Accident (CVA or stroke) or even sudden death due to cardiac arrest.
Therapeutic varies with the underlying cause but can be medical (with drugs such as Na+, K+ and Ca+ channel blockers, beta-blockers and Digoxin) or surgical (ie: Artificial pacemaker).
The following is multiple choice question (with options) to answer.
What is the name for medical doctors that specialize in the diagnosis and treatment of diseases of the heart? | [
"surgeons",
"cardiologists",
"Doctors",
"physicists"
] | B | Cardiologist Cardiologists are medical doctors that specialize in the diagnosis and treatment of diseases of the heart. After completing 4 years of medical school, cardiologists complete a three-year residency in internal medicine followed by an additional three or more years in cardiology. Following this 10-year period of medical training and clinical experience, they qualify for a rigorous two-day examination administered by the Board of Internal Medicine that tests their academic training and clinical abilities, including diagnostics and treatment. After successful completion of this examination, a physician becomes a board-certified cardiologist. Some board-certified cardiologists may be invited to become a Fellow of the American College of Cardiology (FACC). This professional recognition is awarded to outstanding physicians based upon merit, including outstanding credentials, achievements, and community contributions to cardiovascular medicine. |
SciQ | SciQ-5817 | species-identification, zoology, bone-biology, bone
Title: What is this bone from? This object showed up on my fire escape in New York city. It appears to be some kind of bone. It's a bit smaller than an adult human hand. What animal is it from? Given the size and thin/elongated ilia as well as the urban location, I think a domestic cat and/or a raccoon are likely candidates. I'm leaning toward cat.
Cat pelvis:
VCA Hospitals
Ventral view of domestic cat pelvis; Source: BoneID
Raccoon Pelvis
Anterior view of raccoon pelvis; Source: BoneID
I'm not an expert in differentiating these two species' bones. I will note that your specimen is more or less in between the sizes of these two species. Your size is probably closer to the raccoon, but a cat is just more likely given the location.
The most noticeable trait that stands out to me is the size/pointedness of the ischial tuberosity, which better matches that of the cat.
The following is multiple choice question (with options) to answer.
Any place at which two bones are joined is called a what? | [
"constriction",
"modification",
"articulation",
"expression"
] | C | An articulation is any place at which two bones are joined. The humerus is the largest and longest bone of the upper limb and the only bone of the arm. It articulates with the scapula at the shoulder and with the forearm at the elbow. The forearm extends from the elbow to the wrist and consists of two bones: the ulna and the radius. The radius is located along the lateral (thumb) side of the forearm and articulates with the humerus at the elbow. The ulna is located on the medial aspect (pinky-finger side) of the forearm. It is longer than the radius. The ulna articulates with the humerus at the elbow. The radius and ulna also articulate with the carpal bones and with each other, which in vertebrates enables a variable degree of rotation of the carpus with respect to the long axis of the limb. The hand includes the eight bones of the carpus (wrist), the five bones of the metacarpus (palm), and the 14 bones of the phalanges (digits). Each digit consists of three phalanges, except for the thumb, when present, which has only two. The Pelvic Girdle The pelvic girdle attaches to the lower limbs of the axial skeleton. Because it is responsible for bearing the weight of the body and for locomotion, the pelvic girdle is securely attached to the axial skeleton by strong ligaments. It also has deep sockets with robust ligaments to securely attach the femur to the body. The pelvic girdle is further strengthened by two large hip bones. In adults, the hip bones, or coxal bones, are formed by the fusion of three pairs of bones: the ilium, ischium, and pubis. The pelvis joins together in the anterior of the body at a joint called the pubic symphysis and with the bones of the sacrum at the posterior of the body. The female pelvis is slightly different from the male pelvis. Over generations of evolution, females with a wider pubic angle and larger diameter pelvic canal reproduced more successfully. Therefore, their offspring also had pelvic anatomy that enabled successful childbirth (Figure 38.13). |
SciQ | SciQ-5818 | electrostatics
Title: Rubbing of a fur - can the electrons in a fur be ever ran out? As we all know, if we rub ebonite rod with a fur, the rod becomes negatively charged(electrons get passed from fur to rod). But what happens if we will do that many times with the same fur but each time with another ebonite rub? I mean, is it possible that once(at one point) all electrons in this fur will run out? The fur without electrons? And, how can we to restore a previous state of this fur (with balance of protons and electrons)? The reason electrons leave the fur is that there is a favorable potential difference between the electron in the outer shell orbit, and an electron in an outer shell orbit in the rod. (This is a bit of a simplification, but not a misleading one.)
If you were to do this act many times, stealing many electrons (and a lot of negative charge) from the fur, the fur would eventually have a perceptible net positive charge, which could be considered as a charge-per-unit-area $\rho$. This will change the net effective potential for an electron to leave. If $\rho$ becomes big enough, the electrons will stop leaving.
Mind you, at that point, the fur still has plenty of electrons, and even plenty of outer-shell electrons left. It's just that you can't strip any more by rubbing with an ebony rod. However, gradually the fur will regain its electrons from the air, so if you wait long enough, it becomes a good source of electrons again.
The following is multiple choice question (with options) to answer.
In mammals, hair or fur help conserve bodily what? | [
"food",
"water",
"energy",
"heat"
] | D | Conserving heat is also important, especially in small mammals. A small body has a relatively large surface area compared to its overall size. Because heat is lost from the surface of the body, small mammals lose a greater proportion of their body heat than large mammals. Mammals conserve body heat with their hair or fur. It traps a layer of warm air next to the skin. Most mammals can make their hair stand up from the skin, so it becomes an even better insulator. Even humans automatically contract these muscles when they are cold, causing goosebumps (see Figure below ). Mammals also have a layer of fat under the skin to help insulate the body. This fatty layer is not found in other vertebrates. |
SciQ | SciQ-5819 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
Echinoderms are marine organisms that make up which phylum? | [
"chordata",
"echinodermata",
"annelida",
"cnidaria"
] | B | Echinoderms are marine organisms that make up the phylum Echinodermata. They can be found in the ocean from the equator to the poles. There are roughly 6000 living species of echinoderms. They are among the most distinctive organisms within the animal kingdom. Members of the phylum include sea stars (starfish), sand dollars, and feather stars, all shown in Figure below . |
SciQ | SciQ-5820 | 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 kind of membrane do prokaryotic cells have? | [
"cellulose",
"plasma membrane",
"plasma wall",
"cell wall"
] | B | Like other cells, prokaryotic cells have a plasma membrane (see Figure below ). It controls what enters and leaves the cell. It is also the site of many metabolic reactions. For example, cellular respiration and photosynthesis take place in the plasma membrane. |
SciQ | SciQ-5821 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
What is the name of the cell that results when a sperm nucleus fuses with a egg nucleus? | [
"t cell",
"a filament",
"a cytoplasm",
"a zygote"
] | D | When a sperm penetrates the egg, it triggers the egg to complete meiosis. The sperm also undergoes changes. Its tail falls off, and its nucleus fuses with the nucleus of the egg. The resulting cell, called a zygote , contains all the chromosomes needed for a new human organism. Half the chromosomes come from the egg and half from the sperm. |
SciQ | SciQ-5822 | depends on the parameters of the orbit ($$a, \epsilon, \omega$$, i) and the Earth's equatorial radius $$R_E$$ and its $$J_2$$ term.
Let's use 6378137 meters for $$R_E$$ (from this answer) and 1.0826E-03 for $$J_2$$ (from this answer).
The satellite's period $$T$$ in your data table is 15.59029 revolutions per day, or about 5542 seconds. Then use:
$$\omega = \frac{2 \pi}{T} = 0.0011338 \ \text{sec}^{-1}.$$
$$a^3 = \frac{GM}{\omega^2}$$
where GM is Earth's standard gravitational parameter of about 3.986E+14 m^3/s^2. That makes $$a=$$ 6768601 meters, or an altitude of about 390 km.
Plug those all in to the first equation, and we get $$\omega_p = -1.2149 \times 10^{-6} \ \text{sec}^{-1}$$ If we multiply that by 60 days or 5184000 seconds, we get -6.298 which is almost exactly $$-2 \pi$$ or one complete cycle, just what the plot shows!
The argument of perihelion at first looks like it drifts steadily then flips by 180 degrees around day 85, but that's actually a smooth shape change since the eccentricity hits zero and bounces back. That looks like a natural precession as well, and not an orbital maneuver.
The following is multiple choice question (with options) to answer.
What makes a complete orbit around the earth once every 29 1/2 days? | [
"the Sun",
"the moon",
"Gemini",
"Mars"
] | B | |
SciQ | SciQ-5823 | earthquakes, models, mathematics
Title: Is there a general equation to know how big of an area is affected by an earthquake? If you visit USGS earthquakes listing, you get 3 points of information for each earthquake: Location, depth, magnitude. My question is, is there a way to approximate how big of an area is affected? Like if an earthquake happens 20km from San Francisco, how strong does it have to be for someone in SF to be able to feel it? No, there isn't, because the area affected depends on so many factors, some of them unknowable. Magnitude, cause, depth, geology (which may be very variable in different parts of the area) etc. Besides which, the easiest way to tell which areas are affected is to monitor reports from observers. In the final analysis, the data that aid agencies want to know is which areas ARE affected rather than which might theoretically be affected if all relevant factors were known, which they rarely will be.
The following is multiple choice question (with options) to answer.
What general property of an earthquake is used to describe its relative strength? | [
"resonance",
"latitude",
"magnitude",
"amplitude"
] | C | Earthquake magnitude affects how much damage is done in an earthquake. A larger earthquake damages more buildings and kills more people than a smaller earthquake. But that's not the only factor that determines earthquake damage. The location of an earthquake relative to a large city is important. More damage is done if the ground shakes for a long time. |
SciQ | SciQ-5824 | ds.algorithms
Title: Abstract machine or algorithm for line solving a Nonogram I am currently working on a little project where I would like to write an efficient solver for three-dimensional Nonograms.
http://en.wikipedia.org/wiki/Nonogram
So I wanted to ask whether anybody of you know a good way on how to solve a line in a normal 2D Nonogram. The problem is NP-complete btw so finding a robust algorithm that always does it will be quite hard ;-)
But does anybody of you have an idea? It doesn't need to solve everything possible but should do basic checks on a line and see if it can fill out something.
Would be great if anybody could give me tips on how I could achieve this... thanks! ... or if you just want to have fun you can simply grab a lot of useful tips from other (powerful) Nonogram solvers; you can start from here:
http://webpbn.com/pbnsolve.html which will teleport :-) you to:
http://webpbn.com/survey/ and ...
http://www.comp.lancs.ac.uk/~ss/nonogram/ ...
http://www.comp.lancs.ac.uk/~ss/nonogram/list-solvers
You can find detail descriptions of single-line / multi-line solving techniques and descriptions of more complex strategies.
When switching to 3D Nonograms single-line and multi-line strategies are still valid (apply 2D multi-line strategies on each section of your 3D puzzle); but if the 3D puzzle is difficult (or random), an iterated loop with those strategies ends up with many unknown pixels and to proceed you must apply specific 3D strategies.
If your question is more TCS oriented then there are plenty of references in some public downloadable articles: http://www.google.it/search?as_q=nonogram+np&as_filetype=pdf
The following is multiple choice question (with options) to answer.
What is a three dimensional snycline? | [
"a gorge",
"a basin",
"a crust",
"a peak"
] | B | In a syncline, rocks arch downward. A three-dimensional syncline is a basin. |
SciQ | SciQ-5825 | tissue
Title: What are the main differences between lab-grown tissues and natural tissues from living animals? What are the main differences between lab-grown tissues and natural tissues from living animals?
Using a biologist's classic "structure (anatomy) and function (physiology)" idea, I thought about the followings:
Structure:
It might be difficult to recreate the composition of different tissues / cells in living things precisely with artificial methods. This may lead to bad results when the tissue is used for tests of medicines and cosmetics.
Function:
Cells might not function and produce as expected (or is harder to make them function) in artificial compositions, as cells need strictly regulated environments to function correctly.
The following is multiple choice question (with options) to answer.
Rather than being dead, dry, and brittle, what support structures of the human body consist of living tissues and are supplied with blood and nerves? | [
"bones",
"lungs",
"feet",
"hearts"
] | A | Some people think bones are like chalk: dead, dry, and brittle. In reality, bones are very much alive. They consist of living tissues and are supplied with blood and nerves. |
SciQ | SciQ-5826 | biophysics, eyes, human-eye, light, optics
As noted in the comments, the range of human vision almost exactly matches the wavelength region of peak solar irradiance on the Earth's surface. The full width at half maximum range for sunlight is about 300-900 nm.
As noted in the answers to "What is the biological potential for vision of wavelengths outside the human visual range?", shorter wavelengths tend to destroy biological structures and longer wavelength photons don't have enough energy to be easily detected individually.
The human eye doesn't "respond to harmonic frequencies" because it it detects light via quantum processes, which are not the same as the classical resonances such as a vibrating string. Just because a molecule absorbs photons of a given frequency, doesn't mean it will absorb photons of twice that frequency.
Another issue is that if you double the frequency of light, you double its photon energy, which for visible light takes into dangerous wavelengths.
Even for creatures whose eyes work into the ultraviolet, their range doesn't go much below 300 nm, which is not surprising since 300 nm (4 eV) photons can break carbon bonds and 250 nm (4.5 eV) photons can break C-H bonds.
Interestingly, however, the eye has been observed to respond to sub-harmonic frequencies. Intense infra-red light can be seen as green, because two infra-red photons can activate the rhodopsin receptor that normally is activated by a single green photon. This requires very bright infra-red light since such two-photon processes happen rarely.
The following is multiple choice question (with options) to answer.
The entire range of light that can be seen by the human eye without aid is known as what kind of light? | [
"colored light",
"white light",
"infrared light",
"visible light"
] | D | Why is this picture of a cat so colorful? No cat looks like this to the human eye. The picture was taken with a special camera that senses infrared light. This is a form of energy given off by warm objects. Areas that appear yellow are the warmest, and areas that appear purple are the coolest. The picture shows that the cat’s eyes are the warmest part of its head. Why can’t people see images like this without a camera? The answer has to do with the wavelengths of infrared light. Its wavelengths are too long for the human eye to detect. In fact, the human eye can detect light only in a very narrow range of wavelengths, called visible light. You’ll learn more about infrared light, visible light, and other forms of electromagnetic radiation in this chapter. |
SciQ | SciQ-5827 | endocrinology
Title: Abnormal Prolactin Level I want to know what makes the balance of the Prolactin abnormal. Is that related to the presence of a nodule near the pituitary? The main abnormality in prolactin levels is hyperprolactinemia, meaning blood levels of prolactin above the normal range, not during pregnancy or lactation.
The major cause of these abnormal prolactin levels are tumors consisting of pituitary lactotroph cells--called prolactinomas--which secrete prolactin. This is generally corrected with synthetic dopamine analogues, as dopamine negatively regulates secretion of prolactin in lactotroph cells.
Here is a 2010 review with further detail:
http://joe.endocrinology-journals.org/content/206/1/1.full.pdf
The following is multiple choice question (with options) to answer.
An endocrine disease usually involves the secretion of too much or not enough hormone by which gland? | [
"Pituitary",
"endocrine",
"Thyroid",
"Pancreas"
] | B | Diseases of the endocrine system are fairly common. An endocrine disease usually involves the secretion of too much or not enough hormone by an endocrine gland. This may happen because the gland develops an abnormal lump of cells called a tumor. For example, a tumor of the pituitary gland can cause secretion of too much growth hormone. If this occurs in a child, it may result in very rapid growth and unusual tallness by adulthood. This is called gigantism. |
SciQ | SciQ-5828 | states-of-matter, matter
Title: What distinguishes the difference states of matter from solid to BEC and perhaps fermionic condensate? Is it something to do with the behavior of electrons? How many states are there either discovered or predicted? 無
'States of matter' is a question of taxonomy, not of reality, and moreover, it's a result of the conditions surrounding the matter, not its internal properties. Certain combinations of properties give us a hint towards calling something 'solid' or 'liquid', but in truth there are no lines, just a continuous spectrum, and under certain conditions, matter transitions seamlessly through all sorts of states, both mundane and exotic:
Behold: Jupiter
A perfect example of this is Jupiter. Composed primarily of hydrogen, this gas giant consists (conjecturally) of a core of high-temperature hydrogen ice, floating in liquid hydrogen, enveloped in hydrogen gas, moving through interplanetary medium composed of hydrogen plasma.
Except not really: Under these conditions, the classical notions of states of matter break down entirely: Between these states of matter there are no interfaces, just a gradual, continuous transition.
In other words: The distinctive line to separate one state from another you are after doesn't really exist.
The following is multiple choice question (with options) to answer.
What are the four well-known states of matter? | [
"solid, liquid, gas, and wave",
"solid , imine , gas , and plasma",
"solid, liquid, plasma, and metal",
"solid, liquid, gas, and plasma"
] | D | The photo above represents water in three common states of matter. States of matter are different phases in which any given type of matter can exist. There are actually four well-known states of matter: solid, liquid, gas, and plasma. Plasma isn’t represented in the iceberg photo, but the other three states of matter are. The iceberg itself consists of water in the solid state, and the lake consists of water in the liquid state. |
SciQ | SciQ-5829 | botany, terminology, fruit
Title: What is the name of this part in plants, fruits, vegetables? What is the name of this part of the plant, fruit, vegetable? The thing that the plant is connected with the tree and gets nutrients with? The part we usually cut out when eat fruit.
Examples below
Papaya
Banana
Mango 'Stalk' or 'pedicel' would be an appropriate term (see, for example, this paper or this one). Specifically, you could say 'terminal part of the stalk/pedicel', though I don't know if there is a word for that.
Note that the term pedicel is commonly used for the stalk of a flower; it makes sense to use it for fruits too as they are derived from flowers.
The following is multiple choice question (with options) to answer.
What is the term for plants that produce flowers and fruit? | [
"spores",
"angiosperms",
"gymnosperms",
"endosperms"
] | B | Angiosperms are plants that produce flowers and fruit. |
SciQ | SciQ-5830 | organic-chemistry, reaction-mechanism, radicals, fuel, lead
And it wasn't discovered from theory. It was found to work by experimenting with a large variety of alternatives (and, unfortunately, economics, not safety, dominated the choice over other possibilities).
But what is the mechanism? This is harder to determine as there are a large variety of radical reactions possible in air/fuel mixtures. It isn't likely that the key step is the production of oxygen radicals (dioxygen is already a diradical under normal atmospheric conditions). But it is reasonable to assume that highly reactive hydrocarbon radicals play a part (the radicals produced from the linear hydrocarbons in diesel fuel would be more reactive than those from petrol/gasoline fuel). And it is also reasonable that TEL would "mop up" some of the potential radicals produced from heat and compression in a standard spark engine. Inhibiting these, even to a small extent, seems to be enough to reduce the propagation speed of those unwanted early side reactions so that knocking does not initiate early combustion.
BTW, though ethanol does work, it takes about 10% of it in the fuel. Better keep that for drinking and develop other, better and non-toxic, agents.
The following is multiple choice question (with options) to answer.
Why did people stop adding lead to gasoline? | [
"bad smell",
"explosions",
"environmental pollution",
"to expensive"
] | C | Gasoline and oils are complex chemical mixtures designed to burn in a way that will efficiently produce energy while emitting a minimal amount of air pollution. The refining of gasoline has improved engine performance but is much more complicated than simply using the crude products extracted from oil wells, as was common in the late 1800s. Most gasoline contained lead at one time, because this additive helped the engine run more smoothly. However, this caused lead contamination in the environment, so new “unleaded” formulations were created that could be burned smoothly without the addition of poisonous heavy metals. Oils for lubrication have special additives that reduce engine wear. Some special fuel blends have also been created to generate more power in race car engines. |
SciQ | SciQ-5831 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Osseous tissue is the tissue that makes up what? | [
"brain",
"muscle",
"liver",
"bone"
] | D | Bone tissue (osseous tissue) differs greatly from other tissues in the body. Bone is hard and many of its functions depend on that characteristic hardness. Later discussions in this chapter will show that bone is also dynamic in that its shape adjusts to accommodate stresses. This section will examine the gross anatomy of bone first and then move on to its histology. |
SciQ | SciQ-5832 | 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.
What is the initial stage of scienetific investigations? | [
"making predictions",
"observation",
"forming hypothesis",
"asking questions"
] | B | Scientific investigations involve the collection of data through observation, the formation and testing of hypotheses by experimentation, and analysis of the results that involves reasoning. Scientific investigations begin with observations that lead to questions. |
SciQ | SciQ-5833 | electromagnetic-radiation, radio, intensity
There are two factors that determine whether radiation is hamful: flux and frequency.
Flux means roughly the number of photons flowing through a certain area per time.
Frequency means the frequency of each photon.
Power $P$ is related to frequency $\omega$ and flux $\Phi$ via
$$P = \Phi \hbar \omega \, .$$
However, power is not the only thing that determines harmfulness.
It turns out various materials have specific frequencies where they do and do not absorb radiation.
For example, glass does not absorb optical radiation, which is why you can see through it.
The Sun emits power over a range of frequencies but the peak is in the optical (i.e. visible) range.
That comes as no surprise because of course our eyes are evolved to see the radiation light that exists on Earth.
Optical radiation has relatively high energy and because of that it gets readily absorbed by the outer parts of your body (except for clear part of the eyes).
However, we're not usually exposed to enough optical radiation flux to do any harm.
For example, we don't usually encounter strong enough lights to burn us.
A really strong industrial laser would be a counterexample.
On the other hand, the part of the solar spectrum at frequencies just above the optical, known as "ultraviolet", has enough energy to damage your body cells, causing sunburn and skin cancer.
The part of the solar spectrum at frequencies below the optical, known as "infrared", is commonly called "heat".
The infrared is generally too low energy to destroy body cells at the levels coming from the Sun.
Incandescent light bulbs also emit a spectrum of radiation, and the story is relatively similar to the story we told for the Sun.
Now, cell phones, WiFi routers, and microwave ovens all produce microwave radiation, which in the range of 1 GHz frequency.
That's about 100,000 times lower frequency than visible light.
Microwave radiation penetrates your skin and goes through your body.
That's why microwave ovens work; the radiation permeates the food and heats it up.
Compare that to putting food right next to the heating element of a broiler in which case the food's outside cooks very quickly before the whole thing is done.
Anyway, the point is that microwave radiation penetrates your body.
The following is multiple choice question (with options) to answer.
The radiation exposure is determined by the number of what times the quality factor of the radiation? | [
"pounds",
"units",
"rads",
"beacons"
] | C | The radiation exposure is determined by the number of rads times the quality factor of the radiation. |
SciQ | SciQ-5834 | Maybe you should use a different approach.
It can be found that sets with the least number of elements are of the following type:
$$\{0,1,a_1,\dots ,a_m,\frac{n}{2}-a_m,\dots ,\frac{n}{2}-a_1,\frac{n}{2}-1,\frac{n}{2}\}$$
or
$$\{0,1,a_1,\dots ,a_m,\frac{n}{4},\frac{n}{2}-a_m,\dots ,\frac{n}{2}-a_1,\frac{n}{2}-1,\frac{n}{2}\}$$
example $$n \leq 20$$
elements can be found easily with this set
$$\{0,1,3,\dots ,\frac{n}{2}-1,\frac{n}{2}\}$$ number of elements $$2+\frac{n}{4}$$
then
$$\{0,1\}$$ for $$0 \leq n \leq 2$$
$$\{0,1,2\}$$ for $$3 \leq n \leq 4$$
$$\{0,1,3,4\}$$ for $$5 \leq n \leq 8$$
$$\{0,1,3,5,6\}$$ for $$9 \leq n \leq 12$$
$$\{0,1,3,5,7,8\}$$ for $$13 \leq n \leq 16$$
$$\{0,1,3,5,7,9,10\}$$ for $$17 \leq n \leq 20$$
example $$n >20$$
$$\{0,1,3,4,9,10,12,13\}$$ for $$21 \leq n \leq 26$$
The following is multiple choice question (with options) to answer.
What is the smallest class of elements? | [
"halogens",
"noble gases",
"metalloids",
"synthetics"
] | C | Metalloids are the smallest class of elements, containing just six elements. They fall between metals and nonmetals in the periodic table. |
SciQ | SciQ-5835 | fluid-dynamics, friction, drag, flow, viscosity
Title: Friction in a fluid when an object is moving in a fluid(air for example), the air will resist the object's movement: molecules of the air will collide with the surface of the object (no slip condition) and then we will have many layers of fluid "above" the surface of the object due to viscosity of the fluid. My question is: are the layers responsible for the friction between the air and the solid or it is just to the molecules that collide at the surface of the object or both? Tried to comment on question, need 50 rep. (why??)
I believe what you are referring to is viscosity in laminar flow. If I recall correctly, non-laminar flow is a precondition for turbulence, but I believe you can have viscosity which is not turbulent.
Is this the direction you had in mind?
EDIT:
Fluid molecules far away from the object will feel nothing.
Fluid molecules in the object's path will be pushed aside (and exert an equal and opposite force on the object).
As fluid molecules are pushed aside, they come into interaction with fluid close to the object path, and secondary interactions ensue.
So I think the answer to your question is: Both. Particles not in the object's path affect it indirectly, by causing those molecules directly in its path to escape less quickly. Imagine how the fluid density and molecular mass will affect the situation.
The following is multiple choice question (with options) to answer.
What is friction that acts on objects that are moving through a fluid? | [
"mass friction",
"fluid catalyst",
"fluid friction",
"fluid temperature"
] | C | Fluid friction is friction that acts on objects that are moving through a fluid. A fluid is a substance that can flow and take the shape of its container. Fluids include liquids and gases. If you’ve ever tried to push your open hand through the water in a tub or pool, then you’ve experienced fluid friction. You can feel the resistance of the water against your hand. Look at the skydiver in the Figure below . He’s falling toward Earth with a parachute. Resistance of the air against the parachute slows his descent. The faster or larger a moving object is, the greater is the fluid friction resisting its motion. That’s why there is greater air resistance against the parachute than the skydiver’s body. |
SciQ | SciQ-5836 | gravity, general-relativity, newtonian-gravity
Title: Understanding gravity Forgive me if my question has an obvious answer, but I need to know the answer. I always thought that more massive/energetic objects had a stronger force of gravity than less massive ones; that is, the Sun would create a stronger gravitational pull than the Earth does.
Upon looking into Newton's law of universal gravitation, I began to wonder whether I misunderstood this. Does the gravity between the Sun and Earth have an equal force on both? As in, does the Earth pull the Sun with as much force as the Sun does on Earth? If so, would the Sun just resist accelerating to Earth because it is extremely massive? Mass is just an object's resistance toward accelerating from a force, right?
If this is the case, would it apply to GR? Sorry for hypothesizing, I'm honestly trying to get a grasp on it. The magnitude of the force of gravity between two bodies is proportional to the product of their masses:
$$F=G\frac{m_1m_2}{r^2}$$
This doesn't change depending on which body you're applying the force to, i.e. if you interchange the masses. The magnitude is the same.
What does change is the direction of the force. Force is a vector quantity, denoted as $\vec{F}$ or $\mathbf{F}$. If we write the equation for gravity using proper vector notation, we have
$$\mathbf{F}=G\frac{m_1m_2}{|\mathbf{r}_1-\mathbf{r_2}|^2}\frac{\mathbf{r_1}-\mathbf{r_2}}{|\mathbf{r_1}-\mathbf{r_2}|}$$
Here, the positions of the objects are represented by vectors, $\mathbf{r}_1$ and $\mathbf{r_2}$. Additionally, $|\mathbf{x}|$ denotes the norm of a vector $\mathbf{x}$ - its magnitude.
The following is multiple choice question (with options) to answer.
The sun’s gravity is relatively strong because the force of gravity between two objects is directly proportional to their what? | [
"masses",
"tissues",
"Liquids",
"rocks"
] | A | As you can see in this NASA photo, Earth is tiny compared with the massive sun. The sun’s gravity is relatively strong because the force of gravity between two objects is directly proportional to their masses. Gravity between the sun and Earth pulls Earth toward the sun, but Earth never falls into the sun. Instead, it constantly revolves around the sun, making one complete revolution every 365 days. |
SciQ | SciQ-5837 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
What do aquatic arthropods use to exchange gases with the water? | [
"pores",
"lungs",
"nostrils",
"gills"
] | D | Like mollusks and annelids, aquatic arthropods may have gills to exchange gases with the water (discussed below). Terrestrial arthropods, on the other hand, have special respiratory structures to exchange gases with the air. These are described in Figure below . |
SciQ | SciQ-5838 | species-identification, botany, ecology, trees
Title: Identifying a shrub with unusual "many shoots" growth behavior While recently hiking in the southern mountains of New Hampshire, we came across a plant, and some of them were exhibiting what we interpreted to be a disease, or least unusual growth. On some of the nodes, there were a large number of extra stalks:
On each plant, the number and locations of these things varied, and not all of them had it. And we first assumed it was some ivy, or parasite, or separate plant, but it seemed pretty clear to us that it was coming right from the same branch.
We soon saw there were dead versions of this plant, and all of them had this "extra shoot" variation:
So we reasoned that no matter what this thing was -- natural variation or some kind of disease -- it was killing the plants.
Google image search was no help. It possibly identified the plant as a "viburnum", but was unable to help with the growth.
Anyone know what plant this is, or what this growth behavior is the result of? Possibly an example of a "Witch's Broom."
Witch's Broom is a deformity in plants (typically woody species) which typically causes dense patches of stems/shoots to grow from a single point on the plant. The name comes from the broom-like appearance of the stems.1
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas, or viruses.2
Sources:
1. Wikipedia
2. Book of the British Countryside. Pub. London : Drive Publications, (1973). p. 519
Image1. Gardeningknowhow.com
Image2. Iowa state University
The following is multiple choice question (with options) to answer.
How many groups of leaves does poison ivy typically have? | [
"ten",
"three",
"four",
"six"
] | B | Poison ivy plants are wild vines with leaves in groups of three. They grow in wooded areas in most of the United States. Contact with poison ivy may cause a rash in a person allergic to the plant. |
SciQ | SciQ-5839 | electrons, atoms, protons, ionization-energy
Title: How to completely turn a gas into positive or negative ions How would I completely turn a gas into positive ions?
How would I completely turn a gas into negative ions?
Could I simply have a gas in a sealed chamber with an ion generator inside with the power source coming from the outside of said sealed chamber? No one produces a pure gas of ions, because there is no practical way to force
separation of charge that would survive collisions between molecules,
and no way to hold such a gas against repulsion of the like charges.
The only pure ions available for experimentation are in VERY dilute
gasses (vacuum, basically) or in atomic or molecular beams, where tricks are used
to separate out ions with a particular charge-to-mass ratio.
Those tricks require the ions to be in motion, thus commonly make
a beam of ions. The possibility exists of holding ions for long periods
of time in a cyclotron (which directs the beam of ions in a circular path).
Small groups of ions can be held by laser traps, but gas-like random
motion is not really happening there.
The following is multiple choice question (with options) to answer.
This knocks electrons from atoms and turns them into ions? | [
"chemical reactions",
"radiation",
"convection",
"evaporation"
] | B | Long-term or high-dose exposure to radiation can harm both living and nonliving things. Radiation knocks electrons out of atoms and changes them to ions. It also breaks bonds in DNA and other compounds in living things. One source of radiation that is especially dangerous to people is radon. Radon is a radioactive gas that forms in rocks underground. It can seep into basements and get trapped inside buildings. Then it may build up and become harmful to people who breathe it. Long-term exposure to radon can cause lung cancer. |
SciQ | SciQ-5840 | quantum-mechanics, atomic-physics, notation, term-symbols
So how do you know this has happened, instead of the $J_1K$ scheme I showed before? The crucial point is that the inner shell term, $^2\mathrm P$, is written down without a well-defined $J_1$ marked in. This is aided in the NIST notation by the intermediate $\mathrm G$ value for $L$, but this aid may not always be present. This is complicated notation, for sure, but it's mandated by the fact that there are a lot of possible couplings and a lot of states to report, so you need concise notation even if it's a bit obscure.
By the time you're having trouble distinguishing between $LK$ and $J_1K$ schemes, though, you will hopefully be buried deep enough in atomic spectroscopy textbooks that you'll be able to navigate this better than the internet can tell you.
The following is multiple choice question (with options) to answer.
What do you call an incomplete outer shell of an atom? | [
"nucleic shell",
"helium shell",
"motile shell",
"valence shell"
] | D | |
SciQ | SciQ-5841 | taxonomy
Title: Why are sponges sometimes not considered multicellular? I read somewhere (I can't find where) that there is no scientific consensus whether sponges should be considered multicellular organisms.
It seems I don't understand where is the line between unicellular and multicellular life.
I am not able to find a more elaborate explanation of that doubt. What are the reasons for it? Sponges are generally considered as colonial organisms because there is little cell specialization and little separation of function/role. All cells do pretty much the same thing; it looks more like a pile of individual cells than an actual multicellular organism. In reality it is a little bit in between.
In any case, what one wants to call multicellular or unicellular is a matter of definition and preferences. You cannot find the line between unicellular and multicellular because there is no such line that would not be very arbitrary and filled with special cases.
You can study a little more the physiology of sponges and then decide for yourself if it looks sufficiently like a multicellular organism or more like a colony of cells (a colonial organism).
The following is multiple choice question (with options) to answer.
What are the specialized cells of sponges called? | [
"plant cells",
"t cells",
"collar cells",
"helper cells"
] | C | 3. Sponges have specialized cells called collar cells. Describe how collar cells are specialized for the functions they serve. |
SciQ | SciQ-5842 | physiology, cardiology, blood-circulation
Title: What is the quality rate of intrinsic autoregulation in the heart? Autoregulation is the maintenance of constant blood flow to an organ in spite of fluctuations in Blood pressure.
It involves the relaxation of myocardium and contraction.
It is local.
I know that autoregulation is best done in the brain, well in kidneys and badly in skeletal muscle.
I am interested how it is in the heart.
I think it should be at least good.
Brain can be thought more important.
However, I am not sure.
How good is the autoregulation of the blood flow in the heart? My conjecture: Intrinsic regulation is done in the heart the second best, after the brain.
This idea is based on the fact that the brain controls heart's some autonomic functions.
It is an open research question how the autonomic nervous system affects the intrinsic functions of the heart - and the reverse is true too.
To answer this question, we need to understand the autonomic regulation of the heart better i.e. the inner-physiology of the heart's electrical activity.
The following is multiple choice question (with options) to answer.
What organ system is comprised of your heart, blood, and blood vessels all working together? | [
"cardiovascular system",
"thoraxic system",
"nervous system",
"digestive system"
] | A | Your heart pumps blood around your body. But how does your heart get blood to and from every cell in your body? Your heart is connected to blood vessels such as veins and arteries. Organs that work together form an organ system . Together, your heart, blood, and blood vessels form your cardiovascular system . |
SciQ | SciQ-5843 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
What type of cells capture light energy, and use carbon dioxide as their carbon source? | [
"sporozoans",
"chloroplasts",
"blood cells",
"photoautotrophs"
] | D | Photoautotrophs are cells that capture light energy, and use carbon dioxide as their carbon source. There are many photoautotrophic prokaryotes, which include cyanobacteria. Photoautotrophic prokaryotes use similar compounds to those of plants to trap light energy. |
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