source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-6444 | molecular-biology, molecular-genetics, development, sex
Quote from a Review (Yao 2005):
We have just begun to glimpse into the mechanisms underlying ovarian development. Convincing evidence challenges us to reconsider the existing paradigm that describes ovarian development as a default system. The default concept was first proposed in the early 1950s when Jost performed the groundbreaking experiments to demonstrate mechanisms of sex differentiation of reproductive tracts (Jost, 1947, 1953, 1970). The term “default” was not originally intended to describe the developmental status of the ovary. Instead, it is referred to the female reproductive tract or the Mullerian duct based on the fact that the female reproductive tract forms in both XX and XY individuals in the absence of gonads. Indeed, now it has become evident that early ovarian development is an active process involving intrinsic cell fate decisions and complex crosstalks between germ cells and somatic cells. Most intriguingly, the appearance of testicular structures in XX individuals where Sry and its downstream components are absent further raises the improbable question: Could the testicular development be default after all?
The following is multiple choice question (with options) to answer.
The female reproductive organs include the ovaries, fallopian tubes, uterus, and what? | [
"intestines",
"womb",
"vagina",
"bladder"
] | C | The female reproductive organs include the ovaries, fallopian tubes, uterus, and vagina. |
SciQ | SciQ-6445 | genetics
Additional response added as requested:
I see what you are getting at - why do children seem like such individual and unique things sometimes?
In sexual reproduction, the offspring are the product of the shuffling of the parent's genomes through meiosis, where the pairs of chromosomes we have are combined to make a single chromosome that will be half of the children genome.
This process can result in completely novel combinations of genes while conveying many likenesses from the parent. I would guesstimate that this is the major cause of the uniqueness of offspring/children.
Also in mammals there are some cell lines which splice families of genes which will cause offspring to be potentially quite different from either parent. Immune genes for instance are created from scratch from a bunch of genes that the parents give. Making each offspring unique but also the product of the parent's genetic repertoire. This can be significant as it affects health and also to some extent attraction - studies have shown that people who smell attractive to us are immunologically distinct from us.
@David mentions epigenetic variation, which is a more recent significant development. During our life, the germline (sperm/egg) DNA may be chemically labelled depending upon environmental conditions we experience. A famous example is experiencing famine conditions, which caused the children to be born on the small side amongst other effects. More recent studies have shown that this is a widespread mechanism to control cells in our body during our lifetime as well as communicate to our offspring how life is. It is expected that this labeling does not affect us forever - the epigenetic labels change over the course of a generation quite often (we believe).
The following is multiple choice question (with options) to answer.
What do offsprings obtain from their parents in what is called, inheritance? | [
"variations",
"characteristics",
"mutations",
"attributes"
] | B | |
SciQ | SciQ-6446 | human-biology
Title: Why do we sweat after drinking water and running? Why do we sweat after running?
Also we sweat sometime after drinking lots of water. Why it is so?
Can someone please enlighten me in this regard? Exercise, such as running, increases muscle activity. This increases the energy demand of these tissues, which increases the rate of cellular respiration. Respiration releases heat as a by-product, therefore the body is hotter during and after exercise.
Sweating is a homoeostatic mechanism to keep core body temperature constant. It is a response to lower the body temperature. When the body becomes too hot, sweat is released onto the surface of the skin. The water from the sweat then takes some of the excess heat energy from the body and uses it to evaporate. Because water has a relatively large specific heat capacity a lot of heat can be carried away by this method.
The following is multiple choice question (with options) to answer.
Warming up your body before a workout does what to the blood flow? | [
"reduces it",
"stops it",
"increases it",
"minimizes it"
] | C | Sometimes muscles and tendons get injured when a person starts doing an activity before they have warmed up properly. A warm up is a slow increase in the intensity of a physical activity that prepares muscles for an activity. Warming up increases the blood flow to the muscles and increases the heart rate. Warmed-up muscles and tendons are less likely to get injured. For example, before running or playing soccer, a person might jog slowly to warm muscles and increase their heart rate. Even elite athletes need to warm up ( Figure below ). |
SciQ | SciQ-6447 | physical-chemistry, acid-base, equilibrium
You have a solution of weak base. You add a stronger base. The increase in hydroxide concentration leads, by Le Chatelier's principle, to a lower extent of dissociation.*
This is beyond the scope of Ostwald's law, which tacitly assumes the lack of what amounts to a common-ion effect. Ostwald's law holds if the solvent which you're using to dilute your solution does not interfere (or interferes only weakly) with your electrolyte's solubility; the added solvent must serve to decrease the concentration of your electrolyte. Evidently, then, adding a stronger base will interfere with the solubility of your weak base, and is not governed by Ostwald's law.
The following is multiple choice question (with options) to answer.
What is a substance that increases the hydrogen ion concentration of a solution? | [
"base",
"sulfur",
"acid",
"carbon"
] | C | |
SciQ | SciQ-6448 | soft-question, advice-request
Do not depreciate yourself because you are not actively working in theoretical computer science. Most people will not care about your precise background as long as you show that you are curious about their work.
When people are vague about a proof/concept, stay alert and try to guide the conversation by asking a precise question showing your understanding and thus helping your interlocutor to choose which part of the proof he should develop first. This is obviously quite hard and unpredictable because you may not be able to give relevant comments on the go (this happens to everyone even to "theorists"), but if you manage it, then you will likely end up with a very enlightening discussion.
Even "theorists" need time to reload the details of a proof in their head before being able to clearly explain it. Make an appointment by explicitly asking that you are interested in the technical details of X. This will allow for time for your interlocutor and you to prepare, and will ease the discussion. Make sure to have a white board or a piece of paper during the discussion so that you can really go into details.
The following is multiple choice question (with options) to answer.
Scientists ask questions, and then make detailed observations to try to ask more specific questions, in order to develop what? | [
"suggests",
"Tests",
"hypothesis",
"theories"
] | C | A scientist is always trying to find the truth and discover new truths. How can you think like a scientist? Thinking like a scientist is based on asking and answering questions. Though you may not know it, you do this all day long. Scientists ask questions, and then make detailed observations to try to ask more specific questions and develop a hypothesis . They may design and perform an experiment to try to answer their question and test their hypothesis. From the results of their experiment, scientists draw conclusions . A conclusion describes what the evidence tells the scientist. |
SciQ | SciQ-6449 | proteins, translation, mrna, ribosome
Title: What is the advantage of the way eukaryotes initiate translation? The eukaryote and prokaryote mechanism for translation is slightly different. Is there any advantage of the eukaryote translation mechanism ?
Edit : I specifically want to know why eukaryotic ribosome first attaches to tRNA and then to mRNA but prokaryotic ribosome can do this in either order. Is there any advantage of the former ? As far as I understand it (and I'll preface this by saying that initiation is not my strongest point), but prokaryotes utilize the beautiful AGGAGG Shine-Dalgarno sequence. Usually around 8bp upstream of the start codon, it is this sequence that the prokaryotic ribosome seeks out to initiate translation. It does this through a complementary region in the 3' sequence of the ribosomal RNA. Upon complementary binding, the ribosome and mRNA are correctly bound. Convenient!
In eukaryotes, however, there is no consensus SD sequence, so a different mechanism must be used; the complex of 40S and Methionine tRNA serves this purpose. The two together scan the mRNA, looking for an AUG start codon which the tRNA is complementary to. This eventually brings the full ribosome (40S + 60S) together to start translation.
The following is multiple choice question (with options) to answer.
What is the main difference between prokaryotic or eukaryotic cells ? | [
"the type of metabolic waste",
"the presence of a Golgi Apparatus",
"the presence of cell walls",
"the presence of a nucleus"
] | D | The answer depends on if the cell is prokaryotic or eukaryotic. The main difference between the two types of cells is the presence of a nucleus. And in eukaryotic cells, DNA lives in the nucleus. |
SciQ | SciQ-6450 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
Supercontinents have formed at least how many times in earth history? | [
"nine",
"five",
"twenty",
"two"
] | B | The first continents were small but they grew over time. Supercontinents have formed at least five times in Earth history. |
SciQ | SciQ-6451 | atmosphere, clouds, thermodynamics, air-currents
Title: Elevation of Atmosphere differ? Does the atmosphere depth (or how high the air molecules from the ground) of Earth or Mars differ gradually or can there be plumes of atmosphere that reaches into space? If I were able to travel a perfect circle around the equator would the atmosphere differ in elevation? The atmosphere, as a whole, is approximately in hydrostatic equilibrium. This means that the gravity of the earth holds the atmosphere to the earth, preventing its escape, though few molecules may escape every so often.
Mathematically, this can be described by $$\frac{dP}{dr}=-\rho g$$ where P is the pressure, $\rho$ is the density, and $g$ is gravity. Using the Ideal Gas Law $$P=\rho R T$$, where $T$ is temperature and $R$ is the gas constant for air. Assuming that the temperature in the height of a column of the atmosphere is averaged ($\bar{T}$) an equation for the average height of the atmosphere can be found $$P(r,\phi,\lambda)=P_0(\phi,\lambda)exp(-\frac{(r-r_0)g}{R\bar{T}(\phi,\lambda)})=P_0(\phi,\lambda)exp(-\frac{gz}{R\bar{T}(\phi,\lambda)})$$
where $r_0$ is the radius of the earth,$P_0$ is the surface pressure, $r=z+r_0$, where $z$ is the height above the earth's surface, $\phi$ is the latitude, and $\lambda$ is the longitude.
To Summarize:
As the average temperature of the atmosphere increases, the height of the atmosphere will generally increase. This means that the height of the atmosphere will generally be the lowest near the poles, but highest near the equator. There are certainly exceptions to this rule, but this generally works. If you were to go around the equator, it will likely not be a "perfect circle" since the average temperature would have to be exactly the same.
The following is multiple choice question (with options) to answer.
How are layers of the atmosphere divided? | [
"air gradients",
"density gradients",
"color gradients",
"temperature gradients"
] | D | The layers of the atmosphere are divided by their temperature gradients. The lowest layer is the troposphere. All weather takes place in this layer. The next layer is the stratosphere. The stratosphere contains the protective ozone layer. More sunlight strikes at the Equator than at the poles. This is what drives the global winds. Warm air rises, moves poleward, and then sinks when it meets with air moving toward the Equator. The result is six atmospheric circulation cells around the world. There are three cells in each hemisphere. Pollutants enter the atmosphere from a few sources. The most important is fossil fuel burning. Air pollution has bad effects on the environment and on human health. By reducing fossil fuel use we can make the environment cleaner. When ozone depletion was found to be a problem, the world acted. As a result, the ozone hole has stabilized. The hole will be getting smaller over the next decades. |
SciQ | SciQ-6452 | bond
Title: Types of bonds in a molecule For example in dinitrogen pentoxide, $\ce{N2O5}$, covalent as well as coordinate bonds (type of covalent bonds) are present, but it appears that it contains only covalent bond.
What is a proper method to find out which type of bonds are present in a molecule? Electrovalent bonds are easiest to identify. If a compound is made up of a metal and non-metal/non-metallic radical (like carbonate), then, 99.99% times, it contains electovalent bond. If a compound is made up of 2 or more non-metals/non-metallic radicals, then it contains covalent bond. Coordinate covalent bonds appear mostly with compounds containing Hydrogen element. To identify the coordinate covalent bonds, you can draw the branched structural formula of the compound and see if the shared pair of electrons are coming from the same molecule.
The following is multiple choice question (with options) to answer.
What term is used to describe molecules that contain carbon-nitrogen bonds? | [
"compounds",
"nitrites",
"amines",
"ions"
] | C | Amines are molecules that contain carbon-nitrogen bonds. The nitrogen atom in an amine has a lone pair of electrons and three bonds to other atoms, either carbon or hydrogen. Various nomenclatures are used to derive names for amines, but all involve the class-identifying suffix –ine as illustrated here for a few simple examples:. |
SciQ | SciQ-6453 | 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.
Birds have a flow-through respiratory system in which air flows unidirectionally from the posterior sacs into the lungs, then into these? | [
"posterior bronchi",
"anterior air sacs",
"alveoli",
"gills"
] | B | Figure 39.14 (a) Birds have a flow-through respiratory system in which air flows unidirectionally from the posterior sacs into the lungs, then into the anterior air sacs. The air sacs connect to openings in hollow bones. (b) Dinosaurs, from which birds descended, have similar hollow bones and are believed to have had a similar respiratory system. (credit b: modification of work by Zina Deretsky, National Science Foundation). |
SciQ | SciQ-6454 | ocean, ocean-currents, antarctic
Title: Why don't Antarctic waters have more upwellings, when Arctic waters are so rich in upwellings? Formation of ice and hence more dense saltwater sinking happens in both polar regions, creating downwellings. Meanwhile, only a few spots in Antarctica have upwellings
I refer to this image:
https://en.wikipedia.org/wiki/Upwelling#/media/File:Upwelling_image1.jpg First, we might want to distinguish between the different types of upwelling:
Coastal upwelling: It is the best known form of upwelling. Winds in these systems flow parallel to the coast (with the coast to the left in the northern hemisphere or to the right in the southern hemisphere) and generate upwelling dynamics. Surface Ekman balance is setup (in deep enough waters) with water transport being to the right (left) of the wind in the northern (southern) hemisphere. The result is a deficit along the coast that requires a compensating flow in the deeper part of the water column bringing usually colder waters to the surface. If the wind blows in the opposite direction, then downwelling occurs.
The figure from the question refers to coastal upwelling (here in its original website with explaining caption). There is definitely more coastal upwelling in the northern hemisphere because of the abundance of shorelines as a greater amount of landmass is present in that hemisphere.
Source Commons Wikipedia.
Equatorial upwelling: Winds from the east blow and converge along the equator as part of the Intertropical Convergence Zone (ITCZ). While the magnitude of the Coriolis acceleration is zero along the equator, Ekman transport takes place immediately north and south of the equator resulting in surface ocean divergence that requires a compensating flow of denser (nutrient-rich) water upwelled from below.
Source
The following is multiple choice question (with options) to answer.
What are convection currents that occur far below the surface of the ocean called? | [
"flat currents",
"deep currents",
"subsequent currents",
"waves"
] | B | Deep currents are convection currents that occur far below the surface. They are caused by differences in the density of ocean water. |
SciQ | SciQ-6455 | 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.
Cations are attracted to anions, which are ions with what charge? | [
"neutral",
"negative",
"positive",
"similar"
] | B | 2.2 Chemical Bonds Each moment of life, atoms of oxygen, carbon, hydrogen, and the other elements of the human body are making and breaking chemical bonds. Ions are charged atoms that form when an atom donates or accepts one or more negatively charged electrons. Cations (ions with a positive charge) are attracted to anions (ions with a negative charge). This attraction is called an ionic bond. In covalent bonds, the participating atoms do not lose or gain electrons, but rather share them. Molecules with nonpolar covalent bonds are electrically balanced, and have a linear three-dimensional shape. Molecules with polar covalent bonds have “poles”—regions of weakly positive and negative charge—and have a triangular three-dimensional shape. An atom of oxygen and two atoms of hydrogen form water molecules by means of polar covalent bonds. Hydrogen bonds link hydrogen atoms already participating in polar covalent bonds to anions or electronegative regions of other polar molecules. Hydrogen bonds link water molecules, resulting in the properties of water that are important to living things. |
SciQ | SciQ-6456 | 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 non-bony skeleton that forms outside of the body is known as a what? | [
"exoskeleton",
"excitoskeleton",
"endoskeleton",
"exoplate"
] | A | One way early land invertebrates solved these problems was with an exoskeleton. This is a non-bony skeleton that forms on the outside of the body. It supports the body and helps it retain water. As the organism grows, it sheds its old exoskeleton and grows a new one. Figure below shows the discarded exoskeleton of a dragonfly. |
SciQ | SciQ-6457 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
The vagina connects to which internal organ? | [
"artery",
"ovaries",
"valves",
"uterus"
] | D | The vagina is a cylinder-shaped organ found inside of the female body. One end of the vagina opens at the outside of the body. The other end joins with the uterus. During sexual intercourse, sperm may be released into the vagina. If this occurs, the sperm will move through the vagina and into the uterus. During birth, a baby passes from the uterus to the vagina to leave the body. |
SciQ | SciQ-6458 | electromagnetism, electric-circuits, electricity, electric-current
Title: What exactly is AC Amperes In the case of AC, electrons don't go anywhere. So what exactly are amperes in the case of AC current? It is supposed to be the measure of AC current, But obviously, I would argue that since electrons don't really go anywhere in an AC circuit, current as such cannot be measured.
So how do instruments measure amperes in an AC current? I understand that we could measure AC power within a circuit as the force with which the electrons vibrate within a circuit. So, lower the vibration, lower the wattage. All good. It appears that the amperes within an ac circuit are measured simply on the firm belief that voltage input is fixed - which is 110 V or whatever it is expected to be in that region.
So, let's say that I produce an AC current by pedaling a turbine with my legs. Then, how exactly do we measure AC voltage and current? According to me AC power could be measured, but not AC voltage or current. They would simply cancel out, or no? It is easier to measure the intensity and direction of a continuous current by the deflection of a magnet needle like the Oersted experiment.
In the case of AC, we know that something similar is happening in the wire, because of the joule effect and other energy productions. But if we place a compass nearby, the needle doesn't move.
But if we make a coil of wire over a iron core, it works as an electromagnet, that attracts iron with a magnitude that depends on the current. And the attraction is not affected by the change of polarity because what is being attracted is not a permanent magnet, but just an iron object.
That device can be placed inside a clamp meter, where the magnetic field of the wire being measured induces an emf (and a current) on this electromagnet. An iron needle is deflected proportional to induced current, that is proportional to the magnetic field, that is proportional to the wire AC current.
The following is multiple choice question (with options) to answer.
What is the measure of electric current? | [
"volts",
"ampheres",
"watts",
"intensity"
] | B | One advantage of anaerobic respiration is obvious. It lets organisms live in places where there is little or no oxygen. Such places include deep water, soil, and the digestive tracts of animals such as humans (see Figure below ). |
SciQ | SciQ-6459 | physiology, cell-biology
Title: Polarized epithelium and localization of ion channels I'm trying to learn more about polarized epithelial cells of the gut. I am familiar with classic brush border transporters localized to the apical memebrane to facilitate nutrient absorption. I am wondering though, where are ion channels located? I would guess basolaterally since they would be exposed to the extracellular space. I would appreciate a primary reference showing the location of voltage-gated channels in particular as I could not find them myself. Well, that's a first for me. I wouldn't have guessed gut cells would have voltage-gated channels.
This article describes voltage-gated sodium channels on both the luminal and basolateral membranes:
Barshack, I., Levite, M., Lang, A., Fudim, E., Picard, O., Ben Horin, S., & Chowers, Y. (2008). Functional voltage-gated sodium channels are expressed in human intestinal epithelial cells. Digestion, 77(2), 108-117.
http://www.ncbi.nlm.nih.gov/pubmed/18391489
The following is multiple choice question (with options) to answer.
Name a passageway that is shared with the digestive system. | [
"trachea",
"larynx",
"esophagus",
"pharynx"
] | D | Next, air passes through the pharynx, a passageway that is shared with the digestive system. From the pharynx, the air passes next through the larynx, or voice box. |
SciQ | SciQ-6460 | 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 substances function as a long-term energy store in the human body and possess long carbon chains that prevent dissolving in water? | [
"triglycerides",
"steroids",
"hydrocarbons",
"nanoparticles"
] | A | Triglycerides function as a long-term storage form of energy in the human body. Because of the long carbon chains, triglycerides are nearly nonpolar molecules and thus do not dissolve readily in polar solvents such as water. Instead, oils and fats are soluble in nonpolar organic solvents such as hexane and ethers. |
SciQ | SciQ-6461 | thermodynamics, electromagnetic-radiation, terminology, infrared-radiation
Title: Why are only infrared rays classified as "heat rays"? I've often heard that Infrared rays are called "heat rays". However, I feel like this term is a misnomer. Don't all the wavelengths of electromagnetic radiation carry energy?
Judging by how gamma rays are highly penetrating and are dangerous when absorbed by tissues, radiations of lower wavelengths should carry more energy, and should be able to increase the internal energy of the object that absorbed it much more than infrared rays can. This seems consistent with the conservation of energy for an isolated system: $$T_{ER} = \Delta E_{int}$$
where $T_{ER}$ stands for transfer of energy by electromagnetic radiation
Then why are UV rays, X-rays and gamma rays not classified as "heat rays".
Don't all the wavelengths of electromagnetic radiation carry energy?
Yes. And that photon energy $E$ is given by
$$E=h\nu$$
Where $h$ = Planck's constant and $\nu$ = frequency.
But not all frequencies interact with matter in the same way.
Judging by how Gamma rays are highly penetrating and are dangerous
when absorbed by tissues
Very little of the energy of Gamma rays is absorbed by tissue, i.e., tissue is basically transparent to Gamma rays. They can even pass through several inches of lead. But as they pass though human tissue they energy that is absorbed can cause ionizations that damage tissue and DNA. For this reason, it is called ionizing radiation.
...radiations of lower wavelengths should carry more energy, and
should be able to increase the internal energy of the object that
absorbed it much more than Infrared rays can.
The following is multiple choice question (with options) to answer.
Thermal, radiant, electrical, nuclear, and chemical are all types of what? | [
"energy",
"fuel",
"fuel",
"heating"
] | A | The chapter describes thermal energy, radiant energy, electrical energy, nuclear energy, and chemical energy. Which form(s) of energy are represented by each of the following?. |
SciQ | SciQ-6462 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
Coronary arteries ans small in what? | [
"diameter",
"length",
"density",
"height"
] | A | |
SciQ | SciQ-6463 | inorganic-chemistry, redox, combustion
As M. Farooq pointed out a combustion reaction happens quickly, producing heat, and usually light and fire. For example, lets look at combustion reaction of an alkene (a hydrocarbon). If it is a complete combustion, the fire have a blue flame:
$$\ce{C_nH_{2n} + $\frac{3n}{2}$ O2 -> nCO2 + n H2O}$$
If it is a partial combustion, it can have a multiple $\ce{C}$ compounds as products, and have a yellow flame due to presence of elemental $\ce{C}$:
$$\ce{C_nH_{2n} + x O2 -> m C + p CO + $(n-m-p)$CO2 + n H2O}$$
where $x = \frac{2(n-p-m) +p}{2} = \frac{2n-2p-2m +p}{2} = \frac{2n-p-2m)}{2}$. In your reaction would not produce fire and it didn't use either oxygen or other oxidants ($\ce{CuO}$ is not that type of oxidant). It is true that the reaction is a redox reaction.
The following is multiple choice question (with options) to answer.
What occurs when a substance reacts quickly with oxygen? | [
"oxidation",
"convection",
"catalytic conversion",
"combustion reaction"
] | D | A combustion reaction occurs when a substance reacts quickly with oxygen (O 2 ). You can see an example of a combustion reaction in Figure below . Combustion is commonly called burning. The substance that burns is usually referred to as fuel. The products of a combustion reaction include carbon dioxide (CO 2 ) and water (H 2 O). The reaction typically gives off heat and light as well. The general equation for a combustion reaction can be represented by:. |
SciQ | SciQ-6464 | evolution, theoretical-biology, evolutionary-game-theory
Title: Proof of the equivalence between two ways of defining ESS Background
Two common ways of defining what an Evolutionary Stable Strategy (ESS) are:
First definition:
Consider a population composed of populations playing two strategies, $\mathbf{p}$ and $\mathbf{q}$.
Let us denote $W(\mathbf{p})$ the average fitness of the
strategy $\mathbf{p}$. A population consisting of individuals playing $\mathbf{p}$ will be an ESS if, whenever a small amount of deviant individuals playing $\mathbf{q}$, the old type $\mathbf{p}$ fares batter than the newcomers $\mathbf{q}$. This means that for all
$\mathbf{p}\neq \mathbf{q}$,
\begin{equation}
W(\mathbf{p}) > W (\mathbf{q})
\end{equation}
Second definition: $E(\mathbf{p},\mathbf{q})$ is the payoff for $\mathbf{p}$-strategist against a $\mathbf{q}$-strategist. The strategy $\mathbf{p}$ is an ESS if and only if the following conditions are satisfied:
$E(\mathbf{p},\mathbf{p})\geq E(\mathbf{q},\mathbf{p}) \quad \forall
\mathbf{q}$
If $\mathbf{q}\neq \mathbf{p}$ and $E(\mathbf{p},\mathbf{p}) = E(\mathbf{q},\mathbf{p})$, then
$E(\mathbf{p},\mathbf{q})> E(\mathbf{q},\mathbf{q})$
The following is multiple choice question (with options) to answer.
What are the two basic types of competition called? | [
"weak and strong",
"interference and interaction",
"exploitative and beneficial",
"instraspecifc and interspecific"
] | D | Aggressive behavior often occurs when individuals compete for the same resources. Animals may compete for territory, water, food, or mates. There are two basic types of competition: intraspecific and interspecific. |
SciQ | SciQ-6465 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
Algae are much simpler than protozoa. they are aquatic and contain this? | [
"chlorophyll",
"sporozoa",
"cloning factor",
"testes"
] | A | 22.11 Algae Algae are much simpler than protozoa. They are aquatic and contain chlorophyll. Algae can exist as a single cell or as giant seaweeds 60 m in length. Formerly, algae were classified as plants but this was incorrect as algae lack parts of true plants: leaves, stems, roots, xylem, and phloem. Since algae belong in the kingdom Protista, algae is a broad term used to denote all aquatic eukaryotes which photosynthesise; algae can differ in size and shape as well. There are six phyla of algae:chlorophytes (green algae), phaeophytes (brown algae), rhodophytes (red algae), chrysophytes (diatoms), pyrrophytes (dinoflagellates), and euglenophytes (euglenoids). |
SciQ | SciQ-6466 | materials, measurements, sensors, optics, spectrometry
Title: How can I detect black spots? I am researching about ways to continuously determine black spots (size 50+ micron) in our product stream. This stream consists of imperfect spherical polymer beads (size 3 mm) of different materials (ABS, SEBS, etc.) and colors (opaque and transparent). I want to be able to count them as well as characterize them (size).
I have been looking into a couple of options:
Visual observation using computer vision
NIR spectroscopy:
What other options do I have and which one is most effective (preferably also least expensive)?
Update:
In our production plant we produce at 500 kg/hr and the pellets are transported along a conveyor as a monolayer of around 50 cm width at around 5 cm/s. However i can imagine that is simply too complex to begin with and i am not opposed to having a secondary stream with much lower massflow and then upscale in a later stage or just have labscale setup to check samples taken of the productstream. I am ok with an approximate count as long as it is reproducible. I would also be ok with initially only detecting 100+ micron black spots. The simplest method will be a multi-step approach. The first step will be a defective product detection, that gathers general data about the product stream and quarantines defective products. On a parallel path, a small batch of samples will be also sequestered from the main line to be analyzed continuously for detectable defects. A laboratory analysis could then confirm size and count using digital tools.
Recognizing that these are, for the most part, polarized plastics, they should have a fairly consistent low to modest relative permittivity, double to triple the value of air. Regardless of opacity and/or material, a product line with high amount of defects will be unpolymerized or coked plastics, consisting primarily of carbon, which has a detectable higher relative permittivity, nearly five times the value of even the most polar plastics. A static (ultra low frequency) dielectric detector can detect these defects, and quarantine the offending batch.
The following is multiple choice question (with options) to answer.
What is a gram stain used to identify ? | [
"different types of liquids",
"radioactivity",
"acids or bases",
"different types of bacteria"
] | D | Different types of bacteria stain a different color when Gram stain is applied to them. This makes them easy to identify. Some stain purple and some stain red, as you can see in Figure below . The two types differ in their outer layers. This explains why they stain differently. |
SciQ | SciQ-6467 | atmospheric-chemistry
But some researchers have argued it does make a notable contribution in the lower atmosphere, but indirectly. There doesn't appear to be a consensus on how big this effect is (and the Wikipedia reference is old and obsolete). The argument for ozone being a notable contributor is based on the following. Hydrocarbon pollution in the lower atmosphere (often from vehicle emissions) leads to a variety of undesirable reactions some of which lead to the production of ozone (as well as many other irritating components of smog). We really don't want too much smog or ozone in the lower atmosphere because it is bad for health. Some have estimated that it also adds to the warming caused by hydrocarbon emissions (exacerbating the warming potential of methane, for example).
It is hard to judge the estimates of its contribution to warming not least because they rely on models of complex reactions caused indirectly by other pollutants. Also, the big issue with emissions leading to ozone are not its contribution to warming but its contribution to pollution which causes direct harm to people in the short term. In fact regulations around emissions has been striving to reduce those emissions since before we started worrying about global warming. And, many countries have sharply reduced them (this is a major reasons why most western countries insist on catalytic converters in their vehicles). We should reduce ozone pollution by reducing the other emissions that cause it and we have been doing that for decades.
I would argue that ozone is essentially irrelevant to global warming. We should strive to reduce it in the lower atmosphere even if we were not worried by global warming. So even if we can't agree on how big its contribution to warming is (which the literature isn't clear on) we should be reducing it as much as we can for more direct reasons.
And, even if we wanted to report its contribution to warming, the best place to account for it is to add it to the contribution of other emissions (eg methane) rather than to account for it separately as we don't directly emit it from anything.
The following is multiple choice question (with options) to answer.
Burning gas to run our cars is an example of how human activity is contributing to what global event? | [
"ozone change",
"climate change",
"metamorphic change",
"carbon change"
] | B | Flickr:futureatlas. com (http://futureatlas. com/blog/). Human activities like burning gasoline in cars are contributing to a global change in our climate . CC BY 2.0. |
SciQ | SciQ-6468 | periodic-table, history-of-chemistry
Title: Why lanthanides and actinides are shown separate from standard Periodic Table layout? In the standard Periodic Table layout , all the elements up to 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in this layout:
What is the reason behind this structure?
Is this standard layout or can I represent it like this too? The Periodic Table arranges elements in blocks as each type of orbital fills with electrons - $s,p,d,f,g,h$. Alkali metals and alkaline earths are $s$-block filling (but could be one $s$-block slot). $p$-block six electrons to fill are trelides, tetralides, pnticides, chalcogenides, halides, inert gases (but could be one $p$-block slot). Transition metal $d$-block is ten elements (but could be one $d$-block slot). Filling the $f$-block are 14 elements, lanthanoids and actinoids. That gets sloppy to print and the elements are (or at least were) overall obscure. They get condensed.
Representing the Periodic Table has become an an art form. The plain vanilla variety is terse and useful.
http://en.wikipedia.org/wiki/Alternative_periodic_tables
The following is multiple choice question (with options) to answer.
The periodic table of elements is divided into what? | [
"spheres",
"squares",
"groups",
"patterns"
] | B | Each element has its own square in the periodic table. The square contains the chemical symbol for the element, the atomic number, and the atomic weight . The atomic weight of an element is a weighted average of its isotopes. |
SciQ | SciQ-6469 | waves, displacement
$$
u = A\cos(\kappa x - \omega t)
$$
would give $u=A$. On the other hand, you could ask "what is the amplitude of the wave at the origin but at time $t_0>0$?" This would correspond to $x=0$ and $t=t_0$ which would give amplitude
$$
u = A\cos(\omega t_0)
$$
The following is multiple choice question (with options) to answer.
Wave amplitude of a transverse wave is the difference in height between what and the resting position? | [
"a cascade",
"a magnitude",
"a crest",
"a valley"
] | C | Wave amplitude of a transverse wave is the difference in height between a crest and the resting position. Wave amplitude of a longitudinal wave is the distance between particles of the medium where it is compressed by the wave. |
SciQ | SciQ-6470 | organic-chemistry, physical-chemistry, biochemistry, alcohols
Title: Storage of Urine Not all may be favorable to this project, but I will explain what I am trying to do. I work at home, and instead of walking a moderate distance to the bathroom and loosing my focus, I've been, at times, peeing in a 3 Quart Poland Springs water bottle. If you take offense at this, please do not continue reading except to be helpful in the scientific goal. I know this subject won't suit many types of people, so just ignore it if that is your case.
I noticed first of all that urine is not at all as sterile as people say that it is. The rate of growth of bacteria is relatively slow, but as a precaution, I found the need to use additional measures to prevent the growth of bacteria. I settled on the following method: I have two bottles and I add to each bottle about enough salt as can be soluble in the urine and sometimes maybe a little more. The one bottle then fills up throughout the day and is emptied, washed, and refilled with salt. The salt helps to kill the bacteria which would be lingering in the empty bottle. The next day, the bottle stays empty and the other is used.
I would add that I discovered that the bacteria (without the salt) does not usually grow unless the bottle is left with urine for two days. After this, however, that same bottle (without the salt) would retain the bacteria and immediately grow, if used again.
This system works relatively well, so long as it is done every day. It will even withstand 2 days with only moderate growth. (If I should leave it by mistake for longer it can get ugly). Nevertheless, I am still looking to improve upon this. One reason is that, if I drink less water or relieve myself normally, the bottle does not fill in one day. I am looking for someone with knowledge of chemistry to help me find a substance that can be added to this solution which fits a number of common sense criteria. I will also add a list of the substances that I have tried or already considered.
Necessary qualities
The following is multiple choice question (with options) to answer.
What is secreted before ejaculation to neutralize acidic urine remaining in the urethra? | [
"semen",
"pre-cum",
"clear mucus",
"sperm"
] | C | |
SciQ | SciQ-6471 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
Because conifers carry both male and female sporophylls on the same mature sporophyte, they are considered what type of plant? | [
"monoecious",
"bioecious",
"siliceous",
"dioecious"
] | A | Life Cycle of a Conifer Pine trees are conifers (cone bearing) and carry both male and female sporophylls on the same mature sporophyte. Therefore, they are monoecious plants. Like all gymnosperms, pines are heterosporous and generate two different types of spores: male microspores and female megaspores. In the male cones, or staminate cones, the microsporocytes give rise to pollen grains by meiosis. In the spring, large amounts of yellow pollen are released and carried by the wind. Some gametophytes will land on a female cone. Pollination is defined as the initiation of pollen tube growth. The pollen tube develops slowly, and the generative cell in the pollen grain divides into two haploid sperm cells by mitosis. At fertilization, one of the sperm cells will finally unite its haploid nucleus with the haploid nucleus of a haploid egg cell. Female cones, or ovulate cones, contain two ovules per scale. One megaspore mother cell, or megasporocyte, undergoes meiosis in each ovule. Three of the four cells break down; only a single surviving cell will develop into a female multicellular gametophyte, which encloses archegonia (an archegonium is a reproductive organ that contains a single large egg). Upon fertilization, the diploid egg will give rise to the embryo, which is enclosed in a seed coat of tissue from the parent plant. Fertilization and seed development is a long process in pine trees: it may take up to two years after pollination. The seed that is formed contains three generations of tissues: the seed coat that originates from the sporophyte tissue, the gametophyte that will provide nutrients, and the embryo itself. |
SciQ | SciQ-6472 | 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.
Who lack some of the defining traits of chordates? | [
"Childern",
"Adult Mammals",
"Reptiles",
"adult humans"
] | D | Adult humans lack some of the defining traits of chordates. Why are humans still classified in the chordate phylum?. |
SciQ | SciQ-6473 | climate-change, geothermal-heat, crust, thermodynamics, fossil-fuel
Title: Do fossil fuels insulate the crust from the Earth's interior? I was doing a project for my English class, and I came upon the article Energy conservation in the earth's crust and climate change. I can't view the full text of the article, but the abstract piqued my interest:
Do long hydrocarbons in the earth actually have a significant effect in insulating the surface? Also, has the lack of these hydrocarbons resulted in any significant warming of the Earth thus far? Quoting from John Russell's response to this article, "This is arrant nonsense!"
Russell concludes with
How did this paper get through the peer-review and editorial review processes? What technical standards were applied to determine the apparent merit of its contents so as to justify its inclusion in a reputable journal?
Just because something is published in a scientific journal does not mean it is fact. Publication is where science starts rather than ends. Sometimes, pure garbage manages to slip through peer review and get published, even in reputable journals. This is one of those times. Moreover, the publisher of the underlying journal, Taylor & Francis, has had issues with shoddy peer review.
The Earth's energy imbalance is 0.6±0.17 W/m2. The Earth's internal energy budget, the amount of energy that escapes from the interior of the Earth, is 0.087 W/m2, about half the uncertainty in the Earth's energy imbalance. (That largish uncertainty is because the imbalance is a difficult quantity to measure.) Even if all of that 0.087 W/m2 is due to humans removing the Earth's insulating layer of hydrocarbons (it isn't), it does not come close to accounting for the 0.6±0.17 W/m2 imbalance. The numbers don't add up.
Or as John Russell put it in his response to the referenced article, "This is arrant nonsense!"
The following is multiple choice question (with options) to answer.
What does convection within the earth's mantel cause? | [
"hurricanes",
"microorganisms to move",
"volcanos",
"plates to move"
] | D | Convection within the Earth’s mantle causes the plates to move. Mantle material is heated above the core. The hot mantle rises up towards the surface ( Figure below ). As the mantle rises it cools. At the surface the material moves horizontally away from a mid-ocean ridge crest. The material continues to cool. It sinks back down into the mantle at a deep sea trench. The material sinks back down to the core. It moves horizontally again, completing a convection cell. |
SciQ | SciQ-6474 | immunology, immune-system, autoimmune
As for why autoimmunity occurs you also understood the basics, however the devil is in the details: wikipedia does have a much longer list of mechanistically different causes. While its often sufficient to explain immune recognition using 'keys' (T cell receptor / B cell receptor = antibody) and their respective 'locks' (peptides bound to MHC / antigens), the exact process of immune cell activation becomes important in autoimmunity, where cells are wrongly activated. This means that there are many possible points at which the 'security system' of the immune cell maturation can (or rather has to) fail to allow autoimmunity.
As for the cross-reactivity of cells: the difference between the binding of B cells (via antibody/B cell receptor to protein surfaces) and T cells (via T cell receptor to peptide sequences) means that in general T cells are much more likely to show cross reactivity - just because the possibility space of a 10-12aa peptide is much smaller than that of a protein surface (even though the probability is still very low).
Additionally - as stated in the comments to your question - both the immune activation pathway and the issue of cross reactivity, while principally understood, are not 'completely solved'. The immune system is insanely complex just by itself and the addition of interactions with both almost all human proteins AND proteins any kind of pathogen, mean that it will take quite a lot of time until researchers can figure out all the weird quirks caused by the 'wrong' combinations.
The following is multiple choice question (with options) to answer.
Autoimmunity can develop with time, and its causes may be rooted in this? | [
"spontaneous mutation",
"molecular mimicry",
"resistance",
"inheritance"
] | B | Autoimmunity can develop with time, and its causes may be rooted in molecular mimicry. Antibodies and TCRs may bind self antigens that are structurally similar to pathogen antigens, which the immune receptors first raised. As an example, infection with Streptococcus pyogenes (bacterium that causes strep throat) may generate antibodies or T cells that react with heart muscle, which has a similar structure to the surface of S. pyogenes. These antibodies can damage heart muscle with autoimmune attacks, leading to rheumatic fever. Insulin-dependent (Type 1) diabetes mellitus arises from a destructive inflammatory TH1 response against insulin-producing cells of the pancreas. Patients with this autoimmunity must be injected with insulin that originates from other sources. |
SciQ | SciQ-6475 | meteorology, temperature, barometric-pressure
Title: Why do tropical areas have low air pressure? From the question Why are pressure levels raised on warm days?, my understanding is that the air pressure at surface level is not affected by temperature, as the mass of the imagined air column stays the same (even though it's extended higher due to lower density). Then, at any given true altitude, warmer temperatures would correspond to higher pressure. The air column analogy makes a lot of sense to me.
However, I was reading NOAA's explanation of atmospheric circulations, which says "This region would become very hot, with hot air rising into the upper atmosphere. This would create a constant belt of low pressure around the equator". That seems to contradict the concept above.
My guess is, in the air column analogy, when the air column is extended higher, it's "leveled out" with the surrounding air, just like water. So we end up with the column with the same original height but lower density, meaning that the total weight at the bottom is lower than before (which means lower pressure). However, if this is true, then the pressure would be lower at any altitude, not just at the surface.
I'm confused now. Please help, thank you! Your guess is correct. As the column of air gets heated, it expands, and that results in a higher pressure in the upper troposphere.
As a result, the air from this warm column flows outwards along the tropopause. This outflow of air is what causes a reduction in the net air mass within the column, and a subsequent reduction in the surface pressure. Therefore at the surface, the air will flow towards the column; so the air moves in a cyclonic sense:
However, if this is true, then the pressure would be lower at any altitude, not just at the surface.
The surface pressure has indeed reduced, but so has the pressure lapse rate (since the air has expanded upwards). Therefore, in the upper atmosphere, the pressure will actually be higher above the warm surface (as can be seen in the first image).
(Images source: Meteorology by Oxford)
The following is multiple choice question (with options) to answer.
Why does warm air rise higher in the troposphere? | [
"it is more dense than cool air",
"It contains hydrogen",
"it is less flourishing than cool air",
"it is less dense than cool air"
] | D | Air in the troposphere is warmer closer to Earth’s surface. Warm air is less dense than cool air, so it rises higher in the troposphere. This starts a convection cell. Convection mixes the air in the troposphere. Rising air is also a main cause of weather. All of Earth’s weather takes place in the troposphere. |
SciQ | SciQ-6476 | Side doubt: Even though the first experiment (truth and lying) is different from the second experiment, can we still apply total probability theorem? In my book the dependent experiment lies inside the sample space associated with the mutually and exhaustive events.
## marked as duplicate by r.e.s., Henning Makholm, Graham Kemp probability StackExchange.ready(function() { if (StackExchange.options.isMobile) return; $('.dupe-hammer-message-hover:not(.hover-bound)').each(function() { var$hover = $(this).addClass('hover-bound'),$msg = $hover.siblings('.dupe-hammer-message');$hover.hover( function() { $hover.showInfoMessage('', { messageElement:$msg.clone().show(), transient: false, position: { my: 'bottom left', at: 'top center', offsetTop: -7 }, dismissable: false, relativeToBody: true }); }, function() { StackExchange.helpers.removeMessages(); } ); }); }); Nov 20 '17 at 8:47
The following is multiple choice question (with options) to answer.
Getting the same result when an experiment is repeated is called what? | [
"replication",
"mutation",
"initiation",
"repetition"
] | A | Scientists also have to “check their work. ” The results of an investigation are not likely to be well accepted unless the investigation is repeated—usually many times—and the same result is always obtained. Getting the same result when an experiment is repeated is called replication . If research results can be replicated, it means they are more likely to be correct. Repeated replication of investigations may turn a hypothesis into a theory. On the other hand, if results cannot be replicated they are likely to be incorrect. |
SciQ | SciQ-6477 | biochemistry, biophysics, cell-membrane, literature
Title: How does membrane potential vary between intraceullar membranes and the cellular membrane? Question
Does each type of membrane have a different membrane potential? I'm especially interested in answers that can cite academic papers that have attempted to measure membrane potentials.
Discussion
I've asked about the composition of membranes before , and although I recieved some information, I didn't get all the information I was after. This isn't a problem with our community but rather with the field at large: the popular thinking is membranes are membranes are membranes (mostly due to the difficulties in studying membrane biophysics experimentally).
This is how wikipedia defines membrane potential:
Membrane potential (also transmembrane potential or membrane voltage)
is the difference in electric potential between the interior and the
exterior of a biological cell. - Wikipedia
This isn't strictly true. Intracellular membranes also have membrane potentials as one can imagine, and there is some unverified information regarding compartmental pH values. This is why I am interested to find out if there have been studies attempting to quantify this across the cell membrane, and across different subcellular membranes. Yes, various intracellular membranes do have potential differences, but as you can imagine they are more difficult to measure experimentally, so in general data on this is scarce.
Summary
Mitochondrial membrane: 150mV-180mV with negativity on the matrix side. Seth et al 2011
Endoplasmic reticulum membrane: 75-95mV with negativity in the ER. Qin et al 2011, Worley et al 1994
Golgi: No notable membrane potential. Schapiro & Grinstein 2000
Lysosomal: 20mV with more negativity on the cytosolic side. Koivusalo et al 2011
The following is multiple choice question (with options) to answer.
Some membranes have what kind of surfaces exposed to the cytoplasm? | [
"outer",
"bilayer",
"hydrophobic",
"obstructionary"
] | C | |
SciQ | SciQ-6478 | 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.
Plants and fungi cells have what basic cell structure, which animals do not have? | [
"Cell Membrane",
"Lysosomes",
"cell wall",
"Cytoskeleton"
] | C | Plants and fungi cells both have a cell wall, which animals do not have. |
SciQ | SciQ-6479 | 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 way in which the sun produces light is called what? | [
"rays",
"tumescence",
"incandescence",
"photosynthesis"
] | C | Most of the visible light on Earth comes from the sun. The sun and other stars produce light because they are so hot. They glow with light due to their extremely high temperatures. This way of producing light is called incandescence . Incandescent light bulbs also produce light in this way. When electric current passes through a wire filament inside an incandescent bulb, the wire gets so hot that it glows. Do you see the glowing filament inside the incandescent light bulb in the Figure below ?. |
SciQ | SciQ-6480 | spectroscopy
Title: Why does the tungsten filament in a lightbulb produce a full(ish) spectrum instead of tungsten's emission spectrum? I only roughly understand how a spectroscope works, so that may be part of the problem. I don't understand what is different about what causes the materials to emit light. The light emitted by a tungsten filament light bulb is due to heating the tungsten filament to a very high temperature. Tungsten has a high melting temperature so the filament can get very hot. The light is like heating a piece of metal till it glows, and then keep heating it until it is 'white' hot. The light is not due to atomic transitions.
The melting point of Tungsten is around 3410°C (6170°F) and the temperature reached in a light bulb is around 3,000°C
The following is multiple choice question (with options) to answer.
What kind of light bulb contains a thin wire filament made of tungsten that gets hot and glows? | [
"black light",
"LED",
"fluorescent",
"incandescent"
] | D | An incandescent light bulb produces visible light by incandescence. The bulb contains a thin wire filament made of tungsten. When electric current passes through the filament, it gets extremely hot and glows. You can learn more about incandescent light bulbs at the URL below. |
SciQ | SciQ-6481 | solutions, molecules, structural-formula, mixtures, colloids
Title: Is there a way to find the mixture type with just the molecular formulas and masses of the solute and solvent? If you had the molecular formula and molar mass of a solvent and a solute and no other specific information about the two, could one deduce the type of mixture (suspension, colloid, solution) they would create? Formula alone does not give you the structure. But if you have the structure of the molecules, there are molecular/thermodynamic models which take into account group contributions for every section of a molecule. These can help calculate and predict phase behaviour and mixture type. See PC-SAFT as an example.
The following is multiple choice question (with options) to answer.
What do you call a mixture in which some particles settle out of it when it is left standing? | [
"alloy",
"homogenous",
"suspension",
"emulsion"
] | C | A suspension is a heterogeneous mixture in which some of the particles settle out of the mixture upon standing. The particles in a suspension are far larger than those of a solution and thus gravity is able to pull them down out of the dispersion medium (water). The typical diameter for the dispersed particles (the sand) of a suspension is about 1000 times greater than those of a solution (less than approximately two nanometers for particles in solution, compared to greater than 1000 nanometers for particles in suspension). Unlike in a solution, the dispersed particles can be separated from the dispersion medium by filtering. Suspensions are heterogeneous because at least two different substances in the mixture can be identified. |
SciQ | SciQ-6482 | thermodynamics, phase-transition, metals, liquid-state
A correct microscopic picture of the melting transition
The different behavior of many observables characterizes crystalline solids and liquids. However, we should not forget that amorphous solids exist, blurring many possible characterizations of the transition based on the concept of spatial order or, on average static quantities. Dynamical properties remain a much clearer indication of the passage from a solid to a liquid phase. In particular, the apparently simple concept that liquid flow and solid don't is a good starting concept to build intuition on the melting process.
Here, I'll try to underline a few (correct) ideas one can connect to the fact that liquids flow.
The following is multiple choice question (with options) to answer.
What do you call the process of a solid becoming a liquid? | [
"boiling",
"melting",
"vaporizing",
"freezing"
] | B | Substances can change phase—often because of a temperature change. At low temperatures, most substances are solid; as the temperature increases, they become liquid; at higher temperatures still, they become gaseous. The process of a solid becoming a liquid is called melting (an older term that you may see sometimes is fusion). The opposite process, a liquid becoming a solid, is called solidification. For any pure substance, the temperature at which melting occurs—known as the melting point—is a characteristic of that substance. It requires energy for a solid to melt into a liquid. Every pure substance has a certain amount of energy it needs to change from a solid to a liquid. This amount is called theenthalpy of fusion (or heat of fusion) of the substance, represented as ΔHfus. Some ΔHfus values are listed in Table 10.2 "Enthalpies of Fusion for Various Substances"; it is assumed that these values are for the melting point of the substance. Note that the unit of ΔHfus is kilojoules per mole, so we need to know the quantity of material to know how much energy is involved. The ΔHfus is always tabulated as a positive number. However, it can be used for both the melting and the solidification processes as long as you keep in mind that melting is always endothermic (so ΔH will be positive), while solidification is always exothermic (so ΔH will be negative). Table 10.2 Enthalpies of Fusion for Various Substances Substance (Melting Point). |
SciQ | SciQ-6483 | 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.
Once a plant cell becomes specialized, what can they no longer do? | [
"divide",
"cellular respiration",
"osmosis",
"photosynthesis"
] | A | As plant cells grow, they also become specialized into different cell types. Once cells become specialized, they can no longer divide. So how do plants grow after that? The key to continued growth is meristem. Meristem is a type of plant tissue consisting of undifferentiated cells that can continue to divide. |
SciQ | SciQ-6484 | physical-chemistry, nanoscience
Title: What Makes Diamonds Difficult to Produce? Having seen an answer over on Worldbuilding about very strong/dense wood that suggested artificially creating some enzymes that would manufacture diamond/graphene as the cellular binding materials in the tree, I said to myself, "Hold on, I know this won't work: creating diamonds requires high temperature and/or pressures...doesn't it?"
But I was unable to locate any information as to why this is the case: that is, what physical property of the bonds or arrangement of the carbon atoms dictates the intense pressures needed to cause the formation of the crystal lattice? Or is there really nothing standing in the way of a chemical process (i.e. an enzyme constructing it a few atoms at a time, albeit with large energy expenditures and slow timescales) that would do it other than "we don't know how to make that."
The covenant bond energy between two carbon atoms seems pretty high, I'll admit, at 348 kJ/mol, but it's less than some other bonds, say Carbon and Hydrogen at 419 kJ/mol (source). So it doesn't seem like that's the limiting factor. I do know that there is energy stored in the organization of the lattice itself, but I don't know how much that contributes; Wikipedia only helpfully notes that the energy is "greater in materials like diamond than sugar."
The following is multiple choice question (with options) to answer.
The hardest natural substance, diamond is a form of what element? | [
"zirconium",
"carbon",
"zenon",
"hydrogen"
] | B | Diamond is a form of carbon in which each carbon atom is covalently bonded to four other carbon atoms. This forms a strong, rigid, three-dimensional structure (see Figure below ). Diamond is the hardest natural substance, and no other natural substance can scratch it. This property makes diamonds useful for cutting and grinding tools as well as for rings and other jewelry (see Figure below ). |
SciQ | SciQ-6485 | thermodynamics, electromagnetic-radiation, earth, climate-science
Title: When sunlight bounces off the Earth, why isn't the entire spectrum reflected rather than just the infrared portion? I've read that greenhouse gases absorb and reemit sunlight, and that the infrared portion is what bounces off Earth back to space. When sunlight bounces off the Earth, why isn't the entire spectrum reflected rather than just the infrared portion? The reflectivity of the atmosphere, and of the surface itself, is strongly wavelength-sensitive. So while some percentage of any given wavelength is reflected -- and some percentage is absorbed rather than transmitted, the variation over wavelength is what leads to the somewhat misleading statement you refer to. Here's an example of atmospheric absorption, as can be seen at wikipedia
There are also curves of reflectance. $transmittance+absorptance+reflectance = 1$, in case you were wondering :-) .
The reason all this matters is that shorter-wave energy, e.g. visible and some UV, that is absorbed either in the atmosphere or by the ground, is re-emitted at different wavelengths in accordance with black-body theory. In general this leads to a lot of IR-radiation, so if the atmosphere is reflective at these wavelengths, the energy is retained rather than re-emitted to space.
The following is multiple choice question (with options) to answer.
Much of what type of radiation that strikes the planet is reflected back into space? | [
"microwaves",
"magentic radiation",
"gamma rays",
"solar radiation"
] | D | |
SciQ | SciQ-6486 | quantum-mechanics, radiation
Title: Where are the photons coming from? Particles and Antiparticles can annihilate, and they are completely destroyed in the process, which creates photons.
From wikipedia:
An unstable atomic nucleus with an excess of neutrons may undergo β− decay
n → p + e− + -νe
neutron decays into proton, electron, and electron antineutrino.
Unstable atomic nuclei with an excess of protons may undergo β+ decay
p → n + e+ + νe
proton decays into neutron, positron, and electron neutrino.
So, combining these two reactions gives us
n → n + e- + e+ + -ve + ve
neutron decays into neutron, electron, positron, electron antineutrino, and electron neutrino.
When the electron and the positron or the electron antineutrino and the electron neutrino collide and are annihilated, photons are produced. So, taking it a step further
n -> n + ?γ
neutron decays into neutron and ? photons.
So my question is, sorry for the long lead-up, where are these photons are coming from? Also sorry if I broke physics :P
(Note: I know that in β− decay, the neutron actually emits a virtual W- particle which decays into an electron and an electron antineutrino, but thought that wouldn't be relevant. It's here if it is, though!)
(Another note: Sorry for the bad symbolization, SE doesn't seem to be accepting all of the characters) I had similar stupid doubt.
It's coming from binding energy.
The equation you give:
Unstable atomic nuclei with an excess of protons may undergo β+ decay
$$p → n + e^{+} + \nu_{e}$$
proton decays into neutron, positron, and electron neutrino.
How do you think a proton can be converted to neutron which has greater mass?
+ you get positron and neutrinos.
The energy comes from binding energy of nucleons in an multi-proton atom.
When you sum up to
n→ n + $\gamma$
You are actually showing energy released from binding energy.
The following is multiple choice question (with options) to answer.
What particles are formed from a neutron in beta decay? | [
"rust and proton",
"electron and a proton",
"mucus and a proton",
"atom and proton"
] | B | In beta decay, an electron and a proton form from a neutron (another unusual particle, called an antineutrino, is also produced). Only the electron is emitted from the nucleus. How does this change the atomic number and atomic mass of the atom?. |
SciQ | SciQ-6487 | organic-chemistry, nomenclature
Title: Nomenclature of alkenoic acids - which group has priority: the alkene or the acid? Right, how do you systematically name them? Also, do you number them from the double bond end or the Carboxyl end?
Ie would it be something like. 2-methyl Hept-3-enoic acid?
Scuse the bad question and I made up the example, sorry! I'm really confused!
Thanks!! The carboxylic acid moiety takes precedence over the alkene moiety, so the molecule has to be numbered starting from the carboxylic acid carbon. Hence, methacrylic acid, for example, has the systematic IUPAC name of 2-methylpropenoic acid.
The following is multiple choice question (with options) to answer.
What class of acids do carboxylic acids fall under? | [
"carbolic acids",
"inorganic acids",
"organic acids",
"hydrochloric acids"
] | C | Common acids and the polyatomic anions derived from them have their own names and rules for nomenclature. The nomenclature of acids differentiates between oxoacids, in which the H+ ion is attached to an oxygen atom of a polyatomic ion, and acids in which the H + ion is attached to another element. Carboxylic acids are an important class of organic acids. Ammonia is an important base, as are its organic derivatives, the amines. |
SciQ | SciQ-6488 | botany
Title: Do plants absorb toxins from the soil? Consider a plant like Aloe Vera that grows up in a toxic environment where the concentration of pesticides, and materials like lead, mercury, cadmium, arsenic etc is very high(e.g. Marshland dumping yard ). Would that mean that the extract from these plants would contain all these toxic elements. Not "all of them". But yes, plants suck up water from the soil, with everything dissolved in this water - nutrients, heavy metals, poisons. And also they breathe air, and absorb stuff via this route.
There probably are some toxins which will not enter the plant, because their molecules are too large and/or fragile. For example, should a plant root come in contact with snake venom, I cannot imagine that any venom will end up stored in the plant leaves.
Plants also have their own metabolism, so they will change/deactivate some toxins. I've seen claims that some plants "purify" formaldehyde, although I don't trust the sources enough to be sure of that.
But the smaller the poison molecule, and the less similar to stuff which is usually digested in nature, the more likely that it will enter the plant and stick around instead of being broken down. The heavy metals you mentioned are prime candidates. If they are present in the groundwater - or also lead from air pollution, before we banned leaded gasoline - they end up in plants, including food plants. And mushrooms are even more at risk.
Growing food near waste dumps is a known problem in farming, and sometimes makes the news, for example here:
http://bigstory.ap.org/article/mafia-toxic-waste-dumping-poisons-italy-farmlands
The following is multiple choice question (with options) to answer.
Plants can absorb inorganic nutrients and water through their root system, and what gas from the environment? | [
"carbon dioxide",
"chemical dioxide",
"hydrogen dioxide",
"nitrogen dioxide"
] | A | CHAPTER SUMMARY 31.1 Nutritional Requirements of Plants Plants can absorb inorganic nutrients and water through their root system, and carbon dioxide from the environment. The combination of organic compounds, along with water, carbon dioxide, and sunlight, produce the energy that allows plants to grow. Inorganic compounds form the majority of the soil solution. Plants access water though the soil. Water is absorbed by the plant root, transports nutrients throughout the plant, and maintains the structure of the plant. Essential elements are indispensable elements for plant growth. They are divided into macronutrients and micronutrients. The macronutrients plants require are carbon, nitrogen, hydrogen, oxygen, phosphorus, potassium, calcium, magnesium, and sulfur. Important micronutrients include iron, manganese, boron, molybdenum, copper, zinc, chlorine, nickel, cobalt, silicon and sodium. |
SciQ | SciQ-6489 | parasitology
Title: Giardia lamblia cases of infections I am wondering if anyone has seen a data of Giardiasis (Giardia Lamblia) cases in different countries on the world? I have found for different diseases and also for 'diarrhoea diseases' in general, but I need especially for Giardia Lamblia.
Any suggestion where I can try to look for this data will be useful.
Thank you very much! If you have or can get access to it, you might try looking in the Incidence and Prevalence database: http://thomsonreuters.com/incidence-and-prevalence-database/
Another possibility is the GIDEON database: http://www.gideononline.com/. It is possible to sign up for a 15-day trial.
For Europe, statistics are available from the WHO CISID at http://data.euro.who.int/cisid/ (select "all infectious diseases", then "Giardiasis").
The WHO does not have any global statistics available on their website, so otherwise you might have to piece together data from individual publications. Some examples:
Thailand, 2005: http://www.ncbi.nlm.nih.gov/pubmed/16438174
Germany, 2006: http://www.ncbi.nlm.nih.gov/pubmed?term=19404678
United States, 2006-2008: http://www.cdc.gov/mmwr/preview/mmwrhtml/ss5906a2.htm
Portugal, 2002-2008: http://www.parasitesandvectors.com/content/5/1/22
Quatar, 2008: http://www.parasitesandvectors.com/content/4/1/211
Tajikistan, 2009: http://www.parasitesandvectors.com/content/4/1/195
Ivory Coast, 2009: http://www.parasitesandvectors.com/content/4/1/96
Tanzania, 2011: http://www.parasitesandvectors.com/content/6/1/3
Ghana, 2006-2009: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170632/?report=classic
The following is multiple choice question (with options) to answer.
Giardia is an example of a protozoa that uses flagella for what purpose? | [
"light",
"movement",
"reproduction",
"nutrients"
] | B | type of protozoa, such as Giardia, that moves with flagella. |
SciQ | SciQ-6490 | geophysics, earthquakes, plate-tectonics, geography
Title: Why is the Ring of Fire there? The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else?
Any help would be appreciated! This question is very similar to: Why does the "Ring of Fire" pretty much define "Pacific Rim"
The high levels of volcanoes and earthquakes are primarily due to subduction. So why is the Pacific surrounded by subduction zones?
Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it. This destruction of the ocean plate(s) occurs at subduction zones.
This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.
The following is multiple choice question (with options) to answer.
Nearly all earthquakes occur where? | [
"in large cities",
"plate centers",
"plate boundaries",
"in Asia"
] | C | Nearly all earthquakes occur at plate boundaries, and all types of plate boundaries have earthquakes. |
SciQ | SciQ-6491 | zoology, invertebrates, sensory-systems
Regarding the ethics of your "investigation", I'd recommend to just not do it.
Sources:
https://de.wikipedia.org/wiki/Blindschnecke
http://www.animalbase.uni-goettingen.de/zooweb/servlet/AnimalBase/home/species?id=1286
https://en.wikipedia.org/wiki/Cecilioides
http://www.molluscs.at/gastropoda/index.html?/gastropoda/morphology/eyes.html
The following is multiple choice question (with options) to answer.
Conotoxins released by certain marine snails can bring about paralysis in humans, indicating that this toxin attacks what system? | [
"neurological",
"cerebral",
"cardiovascular",
"circulatory"
] | A | Can Snail Venom Be Used as a Pharmacological Painkiller? Marine snails of the genus Conus (Figure 28.25) attack prey with a venomous sting. The toxin released, known as conotoxin, is a peptide with internal disulfide linkages. Conotoxins can bring about paralysis in humans, indicating that this toxin attacks neurological targets. Some conotoxins have been shown to block neuronal ion channels. These findings have led researchers to study conotoxins for possible medical applications. Conotoxins are an exciting area of potential pharmacological development, since these peptides may be possibly modified and used in specific medical conditions to inhibit the activity of specific neurons. For example, these toxins may be used to induce paralysis in muscles in specific health applications, similar to the use of botulinum toxin. Since the entire spectrum of conotoxins, as well as their mechanisms of action, are not completely known, the study of their potential applications is still in its infancy. Most research to date has focused on their use to treat neurological diseases. They have also shown some efficacy in relieving chronic pain, and the pain associated with conditions like sciatica and shingles. The study and use of biotoxins—toxins derived from living organisms—are an excellent example of the application of biological science to modern medicine. |
SciQ | SciQ-6492 | planetary-formation, size, brown-dwarf, red-dwarf, hot-jupiter
Title: Existence of planets larger than their host star? The mass region of objects between ~ 0.5 Jupiter masses and 80 Jupiter masses (gas giants through to brown dwarfs and red dwarfs) is typified by an almost flat relationship with object diameter. There are planets out there which are larger in diameter than some of the smallest stars.
The smallest (currently fusing) star known, EBLM-J0555-57, is estimated to be slightly larger than Saturn (at about 59000 km radius with 85 times Jupiter's mass).
One of the largest planets known that isn't a suspected brown dwarf, WASP-79b is estimated to be twice Jupiter's diameter at 0.9 times Jupiter's mass. Many Hot jupiters and puffy planets with similar measurements are known.
How likely are there to be systems where a planet is larger in diameter than its host star? Are there any examples known?
I am looking for currently fusing stars only, which rules out pulsar planets, etc. The answer to the question depends on the exact definition of planet that is used.
A possible example is the L dwarf 2M 0746+20 (2MASS J07464256+2000321) and its planet 2M 0746+20 b.
The radius of the planet is 12% greater than the radius of the star.
$$\begin{array}{lll}
\hline
\text{} & \text{Mass} & \text{Radius}\\
\hline
\text{Planet} & 12.21 \cdot M_J & 0.970 \cdot R_J\\
\text{Star} & 83.79 \cdot M_J & 0.089 \cdot R_{Sun} = 0.866 \cdot R_J\\
\hline
\end{array}$$
Note: The reported planet mass of $12.21 (± 0.4) \cdot M_J$ is slightly below the deuterium burning limit of 13 Jupiter masses.
The following is multiple choice question (with options) to answer.
What is the second largest planet in the solar system? | [
"Mars",
"Venus",
"saturn",
"jupiter"
] | C | Saturn is the second largest planet in the solar system ( Figure below ). Saturn’s mass is about 95 times Earth's mass. The gas giant is 755 times Earth’s volume. Despite its large size, Saturn is the least dense planet in our solar system. Saturn is actually less dense than water. This means that if there were a bathtub big enough, Saturn would float! In Roman mythology, Saturn was the father of Jupiter. Saturn orbits the Sun once about every 30 Earth years. |
SciQ | SciQ-6493 | 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.
Fruit comes from the ovaries of what types of plants? | [
"deciduous",
"flowering",
"sprouting",
"perennial"
] | B | Although flowers and their components are the major innovations of angiosperms, they are not the only ones. Angiosperms also have more efficient vascular tissues. Additionally, in many flowering plants the ovaries ripen into fruits. Fruits are often brightly colored, so animals are likely to see and eat them and disperse their seeds (see Figure below ). |
SciQ | SciQ-6494 | electric-circuits, potential, electrical-resistance, conductors
These analogies are not exact and are only intended to give you a better feel as to what is happening.
Hope this helps.
The following is multiple choice question (with options) to answer.
Resistors connected end to end are said to be in what? | [
"series",
"lines",
"groups",
"parallel"
] | A | Resistors in Series: All resistors are connected end to end. There is only one river, so they all receive the same current. But since there is a voltage drop across each resistor, they may all have different voltages across them – the sum of the voltage drops will equal the total voltage of the circuit. The more resistors in series the more rocks in the river, so the less current that flows. |
SciQ | SciQ-6495 | inorganic-chemistry, physical-chemistry, concentration, molecular-structure, density
Title: Relationship between molar mass and density in solids In ideal gases, it's pretty clear that 1 mole of gas occupies 22.4 L at STP. By knowing this, it's easy to calculate density given molar mass. However, this isn't true for solids. If I know molar mass of a solid, I cannot derive it's density.
I want to clarify whether my understanding of why we can't derive density in case of solids is correct. For solids, since each solid has its own lattice structure, knowing how the molecules are arranged is necessary, because if there is more space between molecules, it will have a lower density, which isn't really an issue in (ideal) gases where the arrangement of molecules/atoms is uniform. If your sample is solid and crystalline, knowledge of the unit cell's dimension and symmetry (e.g., fcc) and density allows you to determine the molecular mass of your compound.
In fact, in crystallography, you may determine the macroscopic density of your sample (e.g., find a liquid which i) wets your crystals and ii) lets your crystals float) in first place. If you then know the dimensions of the unit cell by the diffraction experiment, knowledge of the chemical formula per unit cell may tell you the number of formula units per unit cell. See e.g, this demonstration about Ne.
The following is multiple choice question (with options) to answer.
Molar mass is equal to density multiplied by what? | [
"molar energy",
"molar weight",
"molar volume",
"molar gravity"
] | C | Molar mass is equal to density multiplied by molar volume. |
SciQ | SciQ-6496 | cell-biology, organelle
Title: Univocal identifying of a plant cell We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts in order to justify my statement.
Now in the exercise, we first had to identify the parts of a cell (which was shown in form of an image) and then in part b) reason whether it was an animal or plant cell.
I had identified a chloroplast and a vacuole and stated that the only cell with this organelles was the plant cell. My teacher answered that I had missed the fact, that the cell had also a cell wall (which is indeed a difference between plant and animal cells).
My question is
Is the fact that the cell had a cell wall necessary in my argumentation, i.e. are there other cells having chloroplasts and a vacuole without being a plant cell?
Could you provide a source which supports, or doesn't support my statement so that I can show it to my teacher?
Thanks in advance Your teacher is right, chloroplasts and vacuoles are not sufficient to define a plant cell.
Amoeba have both chloroplasts (McFadden et al, PNAS, 1994) and vacuoles (Day, J. Morphology, 1927) but they are not plants - and they do not have a cell wall.
Sea slugs eat algae and can "steal" their plastids and keep them working for weeks/months, effectively becoming photosynthetic animals for a while. This is called kleptoplastidy (Pillet, Mob. Genet. Elements, 2013).
The following is multiple choice question (with options) to answer.
What plastid makes and stores other pigments? | [
"sporozoans",
"pores",
"chromoplasts",
"pores"
] | C | Chromoplasts are plastids that make and store other pigments. The red pigment that colors the flower petals in Figure above was made by chromoplasts. |
SciQ | SciQ-6497 | meteorology, atmosphere, wind, air-currents
Title: Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.
What forces would cause such a mass movement of air? Wind is caused by pressure differences. Think of a balloon full of air; poke a hole in it and the air comes out. Why? Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.
There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role. The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:
$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$
In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.
The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel). The RHS represent a number of factors that produce a change in the wind. From left to right:
Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)
The following is multiple choice question (with options) to answer.
What effect causes global winds to blow on a diagonal over the earth's surface? | [
"centrifugal effect",
"dopler effect",
"coriolis effect",
"resonant effect"
] | C | Global winds occur in belts around the globe. They are caused by unequal heating of Earth’s surface. The Coriolis effect causes global winds to blow on a diagonal over the surface. Unequal heating also causes jet streams high in the troposphere. |
SciQ | SciQ-6498 | evolution, life-history
the relatedness of the actor to the recipient (note a relatedness is not necessarily symmetric)
The competition this recipient causes on the actor
The cost (energy cost, risk of being injured or killed) of killing
Many species (ants, wolves) might kill or injured individuals of the same species, when for example there is competition for reaching a status in the hierarchy.
I think that the definition of k-selected species is not very accurate. First because there are limit cases. But also because r and k can relate to the function that describes the population growth of a species or might describe the amount of energy the parents spend into one offspring which is not necessarily the same thing. If we think of the parental care, we can think of the lions. When a male win the right to access to the females of another male, he will kill the babies that might be potential competitors to his progeny (because they take energy from the females or because females are not fertile before having lost their babies).
Killing its own offsprings is certainly not less common in k-selected species. You might think it is such a big cost to kill one of its own offspring when one has few offspring but what is important is to think in percentage. Killing 50% of the progeny has the same cost of an r-selected species than for a k-selected species.
If one has a probability of 10% to be able to raise its offspring to adult age. But this probability raised to more than 20% if it accepts to kill an offspring to save energy for the next offspring, then it wins by doing so. THen we might ask: "so would one make an offspring if it intends to kill it?"
Well it does not necessarily intend to kill it. It might need to decide late in the season whether or not it has better to kill its own offspring.
Then, maybe offspring might be used as a reserve of energy and matter for its siblings or for its parents.
The following is multiple choice question (with options) to answer.
When members of the same species compete for the same resources, it is called what? | [
"natural selection",
"intraspecific competition",
"interspecies competition",
"extinction"
] | B | Intraspecific competition happens when members of the same species compete for the same resources. For example, two trees may grow close together and compete for light. One may out-compete the other by growing taller to get more available light. As members of the same species are usually genetically different, they have different characteristics, and in this example, one tree grows taller than the other. The organism that is better adapted to that environment is better able to survive. The other organism may not survive. In this example, it is the taller tree that is better adapted to the environment. |
SciQ | SciQ-6499 | cell-biology, pharmacology, translation, antibiotics, ribosome
Title: Why does azithromycin not affect human mitochondria? Drugs like tetracyclines, macrolides and aminoglycosides bind to prokaryotic ribosomes. It is interesting that our body too having mitochondria, which have prokaryotic ribosomes, there is little(?) effect seen. It can not be ruled out that the effect may be lesser due to them being organelles. Azithromycin's effect on parasites like Toxoplasma and Plasmodium is due to its effect on the plastid that these Apicomplexans have (Castro-Filice et al. 2014). There are two general points that should be appreciated in relation to this question:
Your statement that mitochondria “have prokaryotic ribosomes” is a misleading simplification. Although mitochondria and plastids are thought to be derived from eubacteria — and their ribosomes have some similarities in antibiotic sensitivity — the structures of their large rRNAs differ (as indeed do those of their small rRNAs and their ribosomal proteins). This is important because the large rRNA (the equivalent of 23S rRNA in E.coli) is the target of many antibiotics, including the macrolide antibiotics, of which azithromycin is a member.
Experiments in vitro have shown that human mitochondrial ribosomes are not sensitive to some of the macrolide antibiotics that inhibit eubacterial ribosomes, whereas those of some lower eukaryotes are.
The following is multiple choice question (with options) to answer.
Antibiotics only target prokaryotic cells - they do not affect fungi, which are not prokaryotic, but instead what? | [
"chloroplasts",
"eukaryotic",
"mammals",
"plants"
] | B | Animal and Human Parasites and Pathogens Fungi can affect animals, including humans, in several ways. Fungi attack animals directly by colonizing and destroying tissues. Humans and other animals can be poisoned by eating toxic mushrooms or foods contaminated by fungi. In addition, individuals who display hypersensitivity to molds and spores develop strong and dangerous allergic reactions. Fungal infections are generally very difficult to treat because, unlike bacteria, fungi are eukaryotes. Antibiotics only target prokaryotic cells, whereas compounds that kill fungi also adversely affect the eukaryotic animal host. Many fungal infections ( mycoses) are superficial and termed cutaneous (meaning “skin”) mycoses. They are usually visible on the skin of the animal. Fungi that cause the superficial mycoses of the epidermis, hair, and nails rarely spread to the underlying tissue (Figure 13.26). These fungi are often misnamed “dermatophytes” from the Greek dermis skin and phyte plant, but they are not plants. Dermatophytes are also called “ringworms” because of the red ring that they cause on skin (although the ring is caused by fungi, not a worm). These fungi secrete extracellular enzymes that break down keratin (a protein found in hair, skin, and nails), causing a number of conditions such as athlete’s foot, jock itch, and other cutaneous fungal infections. These conditions are usually treated with over-the-counter topical creams and powders, and are easily cleared. More persistent, superficial mycoses may require prescription oral medications. |
SciQ | SciQ-6500 | botany, plant-physiology, plant-anatomy
*No others are known, but could definitely exist.
Bibliography
Crafts, A. S. “Phloem Anatomy, Exudation, and Transport of Organic Nutrients in Cucurbits.” Plant Physiology 7, no. 2 (1932): 183–225.
Fischer, A. “Das Siebröhrensystem von Cucurbita.” Berichte Deutsche Botanische Gesell 1 (1883): 276–279.
Fischer, A. “Neue Beiträge Zur Kenntniss Der Siebröhren.” Berichte Über Die Verhandlungen Der Königlich-Sächsischen Gesellschaft Der Wissenschaften Zu Leipzig, Mathematisch-Physische Klasse 38 (1886): 291–336.
Fischer, A. Untersuchungen Über Das Siebröhren System Der Cucurbitaceen. Berlin, 1884.
Turgeon, R. and Oparka, K. “The Secret Phloem of Pumpkins.” Proceedings of the National Academy of Sciences 107, no. 30 (2010): 13201 –13202.
Walz, C. and Giavalisco, P. and Schad, M. and Juenger, M. and Klose, J. and Kehr, J. “Proteomics of Curcurbit Phloem Exudate Reveals a Network of Defence Proteins.” Phytochemistry 65, no. 12 (2004): 1795–1804.
Zhang, B. and Tolstikov, V. and Turnbull, C. and Hicks, L. M. and Fiehn, O. “Divergent Metabolome and Proteome Suggest Functional Independence of Dual Phloem Transport Systems in Cucurbits.” Proceedings of the National Academy of Sciences 107, no. 30 (2010): 13532.
The following is multiple choice question (with options) to answer.
What do bees carry from one plant to another to facilitate plant growth and development? | [
"nutrients",
"pollen",
"spores",
"fungi"
] | B | Bees are beautiful creatures that help plants flourish. They carry pollen from one plant to another to facilitate plant growth and development. But, they can also be troublesome when they sting you. For people who are allergic to bee venom, this can be a serious, life-threatening problem. For the rest of us, it can be a painful experience. When stung by a bee, one first-aid treatment is to apply a paste of baking soda (sodium bicarbonate) to the stung area. This weak base helps with the itching and swelling that accompanies the bee sting. |
SciQ | SciQ-6501 | opencv
There exist many methods to tune the gains. In your case, my suggestion is to start with $K_I=0$ and play with $K_P$ up to the point when you'll get small $e_x$ at steady-state and a residual drift. Only then, slowly increase $K_I$ until the small difference in velocities is brought to zero.
Analogous reasoning applies to the elevation velocity.
The following is multiple choice question (with options) to answer.
Why is the drift velocity negligible? | [
"shows free charges",
"many free charges",
"less free charges",
"need free charges"
] | B | Good conductors have large numbers of free charges in them. In metals, the free charges are free electrons. Figure 20.6 shows how free electrons move through an ordinary conductor. The distance that an individual electron can move between collisions with atoms or other electrons is quite small. The electron paths thus appear nearly random, like the motion of atoms in a gas. But there is an electric field in the conductor that causes the electrons to drift in the direction shown (opposite to the field, since they are negative). The drift velocity v d is the average velocity of the free charges. Drift velocity is quite small, since there are so many free charges. If we have an estimate of the density of free electrons in a conductor, we can calculate the drift velocity for a given current. The larger the density, the lower the velocity required for a given current. |
SciQ | SciQ-6502 | volcanology, measurements, volcanic-hazard, field-measurements
Title: How are data from tiltmeters used to monitor volcanic activity? I've just learned in this answer that tiltmeters (which I assume measure changes in tilt) are used near active volcanos. (Saw a mention in item 4. here also.)
What kind of geological (volcanological?) information can be learned from tilt data? Can it also offer predictive benefits, trigger evacuation warnings? Tiltmeters placed on the flanks of an active volcano can measure changes in the slope angle of the flank. These changes are often inferred to be related to changes in the shape and activity of the magma chamber.
This article provides a quick and dirty example of how these instruments can be used, as well as their limitations.
In this case, the tiltmeters were able to capture the deflation of an erupting magma chamber, but not the precursory inflation. This leads to some inferences about the nature of the magma's ascent through the subsurface.
The article also references studies that were able to detect magma chamber inflation as well.
These kinds of observations definitely add to the body of evidence volcanologists use to assess risk of an eruption, but it's far from a slam dunk.
Here are some examples from that paper, both the long-term trend, and a higher time resolution display during a small eruption:
Fig. 2. Tiltmeter data from V-net (KRMV, KRHV) and Hi-net (MKNH, SUKH) stations during the period from January 23 to February 2, 2011. From here.
Fig. 10. Enlarged view of tiltmeter data during the period from 0:00 to 21:00 on January 26, 2011. Vertical line shows the occurrence time of the small eruption at 7:31 and the beginning of the sub-Plinian eruption, when the amplitude of the seismic tremor increased at 14:49. From here.
The following is multiple choice question (with options) to answer.
Instruments that measure the angle of the slope of a volcano are called what? | [
"velocity meters",
"tilt meters",
"aberration meters",
"angle meters"
] | B | All that magma and gas pushing upward can make the volcano’s slope begin to swell. Ground swelling may change the shape of a volcano or cause rock falls and landslides. Most of the time, the ground tilting is not visible. Scientists detect it by using tiltmeters, which are instruments that measure the angle of the slope of a volcano. |
SciQ | SciQ-6503 | climate-change, oceanography, paleoclimatology, paleontology, climatology
As abundant as they are in living form, diatoms are generally poorly (and unreliably) preserved in an older oceanic fossil record. Importantly, they evolve rather quickly making tracking chemical changes in a single species over time and space impossible. Bulk chemistries may be obtained from fossilized silicic masses and serve as rough indicators of overall diatom abundance and thus system health.
They are, however, used in novel ways: some diatoms live exclusively in sea ice and can be used to assess duration and distribution of that sea ice, itself a record of sea surface temperature (SST):
Diatoms in Arctic regions: Potential tools to decipher environmental changes
SIDEBAR. Diatoms as Sea Ice Proxies
By contrast, forams are well preserved in the fossil record, have a well calibrated evolutionary record, and as carbonates, contain important isotopes whose ratios are sensitive to SST.
The following is multiple choice question (with options) to answer.
What is the term for preserved remains or traces of organisms that lived in the past? | [
"deposits",
"remains",
"bones",
"fossils"
] | D | Fossils are preserved remains or traces of organisms that lived in the past. Most fossils form in sedimentary rock. Fossils can also be preserved in other ways. Fossilization is rare. It’s very unlikely for any given organism to become a fossil. |
SciQ | SciQ-6504 | entomology, habitat
Title: Do hornets return to the same nest after winter each year? I have what I think is a hornet nest on the soffit of my house.
The nest has been removed, however, the hornets keep rebuilding. Also, they have started to swarm the sewer vent pipe (not shown in photo).
If fail to get rid of the hornets this fall, will they return to the same nest next year (or overwinter and continue to live there)?
I'm not sure if this is relevant or not:
To give you an idea of what kind of winters I am dealing with, I am near Toronto, Ontario; the temperature goes down to -25 degrees Celsius.
If fail to get rid of the hornets this fall, will they return to the same nest next year (or overwinter and continue to live there)?
No. The nest, likely made of wood pulp (and maybe mud), will/should degenerate to unusable over the winter, though the bulk could remain for a couple of years. All wasps die, except for the new queens (fertile, mated females) who overwinter in sheltered crevices somewhere.
In spring, it is a single wasp that starts a hive: the new queen. She builds a new, small hive in which to lay eggs, which is added to initially by the queen and then by workers who have hatched.
While she will not return to an old hive, the conditions which appeared advantageous to one queen (shelter from rain, intense sunlight, winds, etc.) will also seem advantageous to other queens, which is why nests appear in the same places year after year.
Edited to add: It appears most likely that the queens that overwinter are "new queens", that is, mated female offspring of the queen. H/T @Brian Krause.
The following is multiple choice question (with options) to answer.
Birds flying thousands of miles south in the winter, then returning to their homes in spring, is a familiar example of what? | [
"emigration",
"evacuation",
"hibernation",
"migration"
] | D | One type of migration that you are probably familiar with is the migration of birds. Maybe you have heard that birds fly south for the winter. In the fall, birds fly thousands of miles to the south where it is warmer. In the spring, they return to their homes. ( Figure below ). |
SciQ | SciQ-6505 | organic-chemistry, alcohols
Title: Does ethanol react with potassium to form potassium ethanolate and hydrogen gas? I'm finding information in Google with the keyword (C2H5OH + K) to find the reaction between $\ce{C2H5OH}$ and $\ce{K}$ and found very little information about it. Just 2-3 related results with contradictory pieces of information.
The first one gave
$$
\ce{K + C2H5OH -> KOH + C2H5},
$$
the second one gave
$$
\ce{2C2H5OH + 2K -> 2C2H5OK + H2},
$$
and the third one gave
$$
\ce{C2H5OH + KOH -> C2H5OK + H2O}
$$
There are no trusted public sources so I'm very baffled. I think that $\ce{C2H5OH}$ will react with $\ce{K}$ to form $\ce{C2H5OK}$ because it looks like the reaction with $\ce{Na}$. But I'm not sure and just want to find a trusted source. Can anyone confirm the true result for this reaction? You can view water as the simplest alcohol, and indeed, water reacts with all of the Group 1 metals to form hydrogen gas and the corresponding metal hydroxide according to the following equation
$\ce{2M + 2HOH -> 2MOH + H2}$
where $\ce{M}$ is the metal.
The same reaction occurs with simple alcohols to produce the corresponding metal alkoxide and hydrogen gas
$\ce{2M + 2ROH -> 2MOR + H2}$
As you increase the hydrocarbon portion of the alcohol, or reduce accessibility to the $\ce{OH}$ portion of the alcohol (e.g. make the alcohol less like water), you slow down the rate of the reaction.
Here is a nice link that compares and discusses the relative reactivities of the Group 1 metals with water.
The following is multiple choice question (with options) to answer.
The hydration of what is what makes many alcohols? | [
"alkenes",
"enzymes",
"malts",
"lipids"
] | A | Many alcohols are made by the hydration of alkenes. |
SciQ | SciQ-6506 | inorganic-chemistry, decomposition
Title: Why doesn't CaO decompose into Ca and O2? Many metal oxides decompose into the free metal and oxygen gas at high temperatures, but why doesn't $\ce{CaO}$ do that? What happens to $\ce{CaO}$ at high temperatures?
This is from problem 2 of the 2011 USNCO local exam:
Oxygen gas can be produced by the decomposition of all
of the following substances EXCEPT
(A) calcium oxide. (B) hydrogen peroxide.
(C) mercury(II) oxide. (D) ozone.
The following is multiple choice question (with options) to answer.
What causes oxides to decompose? | [
"acidity",
"precipitation",
"humidity",
"heat"
] | D | Found as a pure element in nature; oxides decompose with heating. |
SciQ | SciQ-6507 | evolution, mathematical-models, population-biology, population-dynamics, population-genetics
Title: Heterozygosity and overdominance Consider $m$ loci with heterozygote advantage (overdominance) such that the fitness of the two homozygotes is $1-\frac{s}{2}$ and the fitness of the heterozygotes is $1+\frac{s}{2}$, where $s>0$. We'll assume that the fitness of an individual is given by the multiplication of the fitness component on each locus. In consequence, the fitness of the best possible genotype is given by $\left(1+\frac{s}{2}\right)^m$.
According to this book, an individual is heterozygote at $j$ of these $m$ loci with probability
$${m\choose j}\left(\frac{1}{2}\right)^m$$
and the equilibrium population mean fitness $\hat w$ is
$$\hat w = \sum_{j=0}^m {m\choose j}\left(\frac{1}{2}\right)^m \left(1+\frac{s}{2}\right)^j \left(1-\frac{s}{2}\right)^{m-j} = 1$$
I don't understand any of these two equations! Can you help me to understand how they have been calculated?
The following is multiple choice question (with options) to answer.
With codominance, both alleles are expressed equally in what? | [
"prokaryotes",
"heterozygotes",
"homozygotes",
"gametes"
] | B | With codominance, both alleles are expressed equally in heterozygotes. The red and white flower in Figure below has codominant alleles for red petals and white petals. |
SciQ | SciQ-6508 | classical-mechanics
the other car hits you and starts compressing your car's crumple zone.
the collision force exceeds your braking force and your car starts accelerating. Your car's crumple zone is still being compressed.
the crumple zone is fully compressed so both cars are now moving at the same speed and your brakes are slowing both cars.
During phase 1 your car is stationary so you feel no force. If the collision is low speed the other car may come to rest before your car starts to skid, and you feel no force at all.
However all but the most trivial collisions are likely to apply more force than your brakes can resist, and you enter phase 2. To calculate the force you feel in phase 2 is quite involved as you'd have to know the force distance curve for compression of the crumple zone. I did Google to see if I could find this data, but without success. Anyhow, it should be obvious that the force during phase two will be less than you'd feel if the brakes weren't on.
Phase three is interesting because it's where you get the whiplash. Assuming your headrest is properly adjusted your head won't move much in phase two. However when you enter phase three your own brakes will jerk you forward. To reduce this (and as above assuming there are no 18 wheelers around) you should release the brakes.
So for low speed collisions you should leave the brakes off, but for high speed collisions hit the brakes during the collision and release them as soon as the two cars have stopped moving relative to each other.
Having said all this, the collision you describe happened to me a few years ago (I'm sure it's hapened to lots of us) and I hit the brakes and held them on. I'm happy to report I suffered no harm, though my car was a write-off. I would advise my children to always hit the brakes and leave them on. Risking whiplash is better than being pushed across the junction or into the back of the car in front of you.
The following is multiple choice question (with options) to answer.
When hit from behind in a car crash, a passenger can suffer a neck injury called what? | [
"inflammation",
"necklash",
"whiplash",
"twisted neck"
] | C | When hit from behind in a car crash, a passenger can suffer a neck injury called whiplash . Explain in terms of inertia how this occurs, and how headrests can prevent the injury. |
SciQ | SciQ-6509 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
When a species always migrates, what is this type of migration called? | [
"obligate migration",
"genus migration",
"emigration",
"mass migration"
] | A | Although migration is thought of as innate behavior, only some migrating species always migrate (obligate migration). Animals that exhibit facultative migration can choose to migrate or not. Additionally, in some animals, only a portion of the population migrates, whereas the rest does not migrate (incomplete migration). For example, owls that live in the tundra may migrate in years when their food source, small rodents, is relatively scarce, but not migrate during the years when rodents are plentiful. Foraging Foraging is the act of searching for and exploiting food resources. Feeding behaviors that maximize energy gain and minimize energy expenditure are called optimal foraging behaviors, and these are favored by natural section. The painted stork, for example, uses its long beak to search the bottom of a freshwater marshland for crabs and other food (Figure 45.36). |
SciQ | SciQ-6510 | biochemistry
Title: Bradford Reagent Disposal I am a graduate student volunteering in a professor's lab being tasked with finding out how to dispose of certain hazardous materials. I have encountered a problem with disposing of Bradford's Reagent. I have checked online, but am running into problems due to the methanol component of this compound. Can someone help me with the proper disposal procedure? Thank you in advance. I would strongly suggest to ask someone in your lab about this, they will have a better idea about the different waste disposal methods you have available.
In general you would dispose anything that contains organic solvents like methanol in a waste container for generic solvent waste. You should have something like that somewhere in the lab.
One thing you always have to keep in mind is to never put anything still reactive into your waste container. A popular example would be a strong oxidizing agent, putting that into a solvent waste container is dangerous and could e.g. ignite the waste. This is not an issue in this case, but you should always keep that in mind.
Another aspect is the pH of the waste, in many cases the waste disposal facility will only accept reasonably neutral waste, so you should neutralize your waste before putting it into a container. Neutralizing it inside the container can be much more annoying. This might not be necessary if you have a dedicated acidic waste, you'll have to ask someone in your lab about that. The Bradford reagent is strongly acidic, so you'll have to pay attention to this aspect.
The following is multiple choice question (with options) to answer.
How are valuable metabolites recovered? | [
"osmosis",
"metabolism",
"replication reaction",
"reabsorption"
] | D | Flame Cells of Planaria and Nephridia of Worms As multi-cellular systems evolved to have organ systems that divided the metabolic needs of the body, individual organs evolved to perform the excretory function. Planaria are flatworms that live in fresh water. Their excretory system consists of two tubules connected to a highly branched duct system. The cells in the tubules are called flame cells (or protonephridia) because they have a cluster of cilia that looks like a flickering flame when viewed under the microscope, as illustrated in Figure 41.10a. The cilia propel waste matter down the tubules and out of the body through excretory pores that open on the body surface; cilia also draw water from the interstitial fluid, allowing for filtration. Any valuable metabolites are recovered by reabsorption. Flame cells are found in flatworms, including parasitic tapeworms and free-living planaria. They also maintain the organism’s osmotic balance. |
SciQ | SciQ-6511 | evolution
Title: Homologous structures under Lamarck I've read that Lamarck's theory doesn't explain homologous structures.
But, what about the following hypothetical under Lamarck's theories:
A population develops an adaptation to its environment
Part of the adapted population moves away
The adaptation is passed onto the population's offspring
All offspring of the original population have the adaptation, regardless of whether or not their ancestors moved away
Isn't this adaptation a homologous structure? I agree with you that I can't see why Lamarck's hypothesis could not explain the presence of homologous structures.
The link you offer also claim that Larmarck's hypothesis would fail to explain "Biogeographical diversity patterns". While this expression is a little vague, I would fail to understand why Lamarck's hypothesis would fail to explain patterns of biogeographical diversity.
The phrasing of your scenarios (absence of the term allopatric speciation, usage of the term "develops" instead of "evolves" of just "adapts") suggests that you may take advantage of an intro course to evolutionary biology such as the short and good course by UC Berkeley called Understanding Evolution
The following is multiple choice question (with options) to answer.
Structures that have lost their use through evolution are called _______ | [
"vestigial structures",
"residual structures",
"symbiotic structures",
"primordial structures"
] | A | Some of the most interesting kinds of evidence for evolution are body parts that have lost their use through evolution ( Figure below ). For example, most birds need their wings to fly. But the wings of an ostrich have lost their original use. Structures that have lost their use through evolution are called vestigial structures . They provide evidence for evolution because they suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose. |
SciQ | SciQ-6512 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What does continental crust grade into at continental margins? | [
"oceanic crust",
"ocean floor",
"remnants crust",
"storm crust"
] | A | Think of a continent, like North America. Surrounding the continent are continental margins . Continental crust grades into oceanic crust at continental margins. Continental margins are under water. Almost all of North America sits on the North American Plate ( Figure below ). Both sides of the continent have continental margins, but each is very different. One continental margin of North America is an active margin. The other is a passive margin. Can you guess which is which?. |
SciQ | SciQ-6513 | organs, lifespan
Title: Organs lifespan out of the body What organ can be conserved outside of the body for the longest time and still function when reimplanted? Depends what you consider an organ. Typically though it's the cells which require the most metabolic activity which have the shortest life span. The kidney is the most of the major internal organs with up to 36 hours with liver coming second at up to 16 hours.
The following is multiple choice question (with options) to answer.
What body system consists of organs that break down food, absorb nutrients, and eliminate waste? | [
"lymphatic system",
"hormonal system",
"skeletal system",
"digestive system"
] | D | The digestive system consists of organs that break down food, absorb nutrients, and eliminate waste. |
SciQ | SciQ-6514 | 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.
Some samples of matter appear to have properties of solids, liquids, and/or gases at the same time. this can occur when the sample is composed of many what? | [
"small pieces",
"turn pieces",
"large pieces",
"few pieces"
] | A | Some samples of matter appear to have properties of solids, liquids, and/or gases at the same time. This can occur when the sample is composed of many small pieces. For example, we can pour sand as if it were a liquid because it is composed of many small grains of solid sand. Matter can also have properties of more than one state when it is a mixture, such as with clouds. Clouds appear to behave somewhat like gases, but they are actually mixtures of air (gas) and tiny particles of water (liquid or solid). The mass of an object is a measure of the amount of matter in it. One way to measure an object’s mass is to measure the force it takes to accelerate the object. It takes much more force to accelerate a car than a bicycle because the car has much more mass. A more common way to determine the mass of an object is to use a balance to compare its mass with a standard mass. Although weight is related to mass, it is not the same thing. Weight refers to the force that gravity exerts on an object. This force is directly proportional to the mass of the object. The weight of an object changes as the force of gravity changes, but its mass does not. An astronaut’s mass does not change just because she goes to the moon. But her weight on the moon is only one-sixth her earth-bound weight because the moon’s gravity is only one-sixth that of the earth’s. She may feel “weightless” during her trip when she experiences negligible external forces (gravitational or any other), although she is, of course, never “massless. ” The law of conservation of matter summarizes many scientific observations about matter: It states that there is no detectable change in the total quantity of matter present when matter converts from one type to another (a chemical change) or changes among solid, liquid, or gaseous states (a physical change). Brewing beer and the operation of batteries provide examples of the conservation of matter (Figure 1.8). During the brewing of beer, the ingredients (water, yeast, grains, malt, hops, and sugar) are converted into beer (water, alcohol, carbonation, and flavoring substances) with no actual loss of substance. This is most clearly seen during the bottling process, when glucose turns. |
SciQ | SciQ-6515 | 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.
Stimuli in the brain, stomach, and small intestine activate or inhibit production of what secretion? | [
"metabolic juice",
"sweat",
"gastric juice",
"digestive juice"
] | C | Gastric Secretion The secretion of gastric juice is controlled by both nerves and hormones. Stimuli in the brain, stomach, and small intestine activate or inhibit gastric juice production. This is why the three phases of gastric secretion are called the cephalic, gastric, and intestinal phases (Figure 23.17). However, once gastric secretion begins, all three phases can occur simultaneously. |
SciQ | SciQ-6516 | 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.
What is the term for a symbiotic relationship in which one species benefits while the other species is not affected? | [
"parasitism",
"mutualism",
"commensalism",
"pollenation"
] | C | Commensalism is a symbiotic relationship in which one species benefits while the other species is not affected. An example is the relationship between birds called cattle egrets and cattle (see Figure below ). Cattle egrets feed on insects. They follow cattle herds around to take advantage of the insects stirred up by the feet of the cattle. The egrets get ready access to food from the relationship, whereas the cattle are not affected. |
SciQ | SciQ-6517 | h. Evaluate C.
i. Compute Q(7), the amount of glucose produced during the day.
Exercise 10.3.5 “Based on studies using isolated animal pancreas preparations
maintained in vitro, it has been determined that insulin is secreted in a biphasic manner in response to a marked increase in blood glucose. There is an initial burst of insulin secretion that may last 5-15 minutes, a result of secretion of preformed insulin secretory granules. This is followed by more gradual and sustained insulin secretion that results largely from biosynthesis of new insulin molecules. ” (Rhoades and Tanner, P 710)
a. A student eats a candy bar at 10:20 am. Draw a graph representative of the rate of insulin secretion between 10:00 and 11:00 am.
b. Draw a graph representative of the amount of serum insulin between 10:00 and 11:00. Assume that insulin is degraded throughout 10 to 11 am at a rate equal to insulin production before the candy is eaten, and that serum insulin at 10:00 was Iq.
CHAPTER 10. THE FUNDAMENTAL THEOREM OF CALCULUS
468
c. Write an expression for the amount of serum insulin, I(t), for t between 10:00 and 11:00 am.
Exercise 10.3.6 Equal quantities of gaseous hydrogen and iodine are mixed resulting in the reaction
which runs until I 2 is exhausted [H 2 is also exhausted). The rate at which I 2 disappears is ^°’^ 2 gm/sec. How much I 2 was initially introduced into the mixture?
a. Sketch the graph of the reaction rate, r(t) = jp^yi-
b. Approximately how much I 2 combined with H 2 during the first second?
c. Approximately how much I 2 combined with H 2 during the second second?
d. Let Q(x) be the amount of I 2 that combines with H 2 during time 0 to 2; seconds. Write an integral that is Q(x).
e. What is Q\x)l
f. Compute W'{x) for W(x) = =^.
g. Show that there is a number, C, for which Q(x) = W(x) + C.
h. Show that C = 0.2 so that Q(x) = 0.2 – g.
The following is multiple choice question (with options) to answer.
What does the a1c test measure over the past two to three months? | [
"blood-glucose levels",
"RBC levels",
"cholesterol levels",
"albumin levels"
] | A | Endocrinologist An endocrinologist is a medical doctor who specializes in treating endocrine disorders. An endocrine surgeon specializes in the surgical treatment of endocrine diseases and glands. Some of the diseases that are managed by endocrinologists include disorders of the pancreas (diabetes mellitus), disorders of the pituitary (gigantism, acromegaly, and pituitary dwarfism), disorders of the thyroid gland (goiter and Graves’ disease), and disorders of the adrenal glands (Cushing’s disease and Addison’s disease). Endocrinologists are required to assess patients and diagnose endocrine disorders through extensive use of laboratory tests. Many endocrine diseases are diagnosed using tests that stimulate or suppress endocrine organ functioning. Blood samples are then drawn to determine the effect of stimulating or suppressing an endocrine organ on the production of hormones. For example, to diagnose diabetes mellitus, patients are required to fast for 12 to 24 hours. They are then given a sugary drink, which stimulates the pancreas to produce insulin to decrease blood-glucose levels. A blood sample is taken one to two hours after the sugar drink is consumed. If the pancreas is functioning properly, the blood-glucose level will be within a normal range. Another example is the A1C test, which can be performed during blood screening. The A1C test measures average blood-glucose levels over the past two to three months. The A1C test is an indicator of how well blood glucose is being managed over a long time. Once a disease such as diabetes has been diagnosed, endocrinologists can prescribe lifestyle changes and medications to treat the disease. Some cases of diabetes mellitus can be managed by exercise, weight loss, and a healthy diet; in other cases, medications may be required to enhance insulin’s production or effect. If the disease cannot be controlled by these means, the endocrinologist may prescribe insulin injections. In addition to clinical practice, endocrinologists may also be involved in primary research and development activities. For example, ongoing islet transplant research is investigating how healthy pancreas islet cells may be transplanted into diabetic patients. Successful islet transplants may allow patients to stop taking insulin injections. |
SciQ | SciQ-6518 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
What is the term for liquid waste formed by kidneys? | [
"blood",
"sperm",
"urine",
"feces"
] | C | Urine is a liquid waste formed by the kidneys as they filter the blood. If you are getting plenty of fluids, your urine should be almost clear. But you might have noticed that sometimes your urine is darker than usual. Do you know why this happens? Sometimes your body is low on water and trying to reduce the amount of water lost in urine. Therefore, your urine gets darker than usual. Your body is striving to maintain homeostasis through the process of excretion. |
SciQ | SciQ-6519 | thermodynamics, solid-state-physics, electric-current, conductors, metals
Title: Why is the heat flow in metals slower than the current flow? When we apply a voltage across a metallic conductor, the current starts to flow almost instantaneously. But when a temperature difference is established across the same conductor, the flow of heat is much slower. It takes larger time for the heat to reach from one end to the other than the current. Why is this so? The current flows almost instantaneously because it is driven by an electric field which appears across the conductor almost instantaneously (near the speed of light). All electrons in the conductor are set into motion by a chain reaction. Collectively they all move through the conductor at what is called the drift velocity at the same time.
By contrast, heat transfer by conduction requires the transfer of energy by collisions between particles in the material that starts at the high temperature end of the conductor and progresses gradually to the low temperature end of the conductor. In the case of metals, the particles are primarily electrons.
Hope this helps.
The following is multiple choice question (with options) to answer.
Why does metal conduct heat and electricity so well? | [
"electromagnetism",
"free flowing photons",
"free flowing electrons",
"insulation"
] | C | The metallic bonding model explains the physical properties of metals. Metals conduct electricity and heat very well because of their free-flowing electrons. As electrons enter one end of a piece of metal, an equal number of electrons flow outward from the other end. When light is shone on to the surface of a metal, its electrons absorb small amounts of energy and become excited into one of its many empty orbitals. The electrons immediately fall back down to lower energy levels and emit light. This process is responsible for the high luster of metals. |
SciQ | SciQ-6520 | botany, entomology
Title: What is this small white insect on my plants? Environment
I have a large amount of plants in an old industrial loft apartment.
I live in Rochester, New York.
I ship plants in from across the US, often exotic ones.
Observations
A few months ago, I noticed that two of my Sarracenia plants in my carnivorous plant bog were not growing anymore. Upon cutting them out as to not disrupt the live sphagnum moss grow medium, I noted that one of the insects in question had burrowed its way down into the core of the plant. I assume this to be the cause of the growing issue.
Today I noticed that one of my grape plants and Colocasia plants were covered in these bugs at different stages of growth. They range from white specs to ~3mm with the tail thing.
These insects appear sedentary. I have never seen one move, except when I cut the one out of the center of the plant.
Here is a picture of the bug, which was difficult to get due to the size.
Research
I looked through a variety of different "common insect" sites as well as some insect identification sites but I was unable to find anything remotely similar.
I have only elementary knowledge of insects. Any pointers in the right direction would be appreciated. Mealybug; don't know much about them.
The following is multiple choice question (with options) to answer.
Liverworts are small plants that grow close to what? | [
"tree tops",
"houses",
"ground",
"beaches"
] | C | Liverworts are small plants that grow close to the ground. |
SciQ | SciQ-6521 | nuclear-physics, radioactivity, quantum-chemistry
Title: What happens to covalent bonds after the nuclear transmutation of an atom in a molecule? What happens when we have a decaying atom in a molecule, which has covalent bonds with other atoms? I assume some of the bonds will cease to exists, but I did not manage to find any rule about which bonds will be affected.
For example we have radiocarbon: ${^{14}_{6}C}$ with 4 bonds: -H, =O, -OH (so the molecule is HCOOH) and the carbon transmutates into ${^{14}_{7}N^{+}} + \beta^-$. What will be the new molecule or at least the intermediate after the decay?
edit:
I have very good stable candidates: https://en.wikipedia.org/wiki/Nitrosonium
${HONO + H^+<=>NO^+ + H_2O}$
It is almost certain that $HONO$ will be the final product, since it is more stable than the $NO^+$. The question is how will the molecule rearrange after the transmutation, so after $HCOOH \rightarrow [HN^+OOH] + \beta^-$. The transmutation is interesting as well, since the nitrogen has smaller atomic radius, so all of the electrons will move closer to the nucleus. Does somebody have any clue what exactly happens with the valence shell of the atom and with the other electron shells right after the transmutation?
(Sorry if the question appears to be off-topic here, but I don't think it belongs to chemistry either, it involves both topics.) The energy of the decay has little to say about whether the covalent bond will remain after the decay. The reason is because the $\beta$-decay electron (or positron since the question doesn't specify) will be moving so fast (compared to the orbital electrons that the cross-section for scattering will be quite small. Since scattering off the orbital electrons is the only mechanism for transfer of the decay energy to the molecule (aside from a minuscule recoil of the decaying nucleus to conserve momentum), the most likely consequence is that the rearrangement of orbitals in response to the increase or decrease of nuclear charge of the decaying atom will decide the question.
The following is multiple choice question (with options) to answer.
What do atoms make by rearranging their chemical bonds in a reactant? | [
"compounds",
"solutions",
"products",
"minerals"
] | C | When a chemical reaction occurs, the atoms in the reactants rearrange their chemical bonds to make products. The new arrangement of bonds does not have the same total energy as the bonds in the reactants. Therefore, when chemical reactions occur, there will always be an accompanying energy change. In some reactions, the energy of the products is lower than the energy of the reactants. Thus, in the course of the reaction, the substances lose energy to the surrounding environment. Such reactions are exothermic and can be represented by an energylevel diagram like the one in http://catalog. flatworldknowledge. com/bookhub/reader/2547 gob-ch07_s04_f01. In most cases, the energy is given off as heat (although a few reactions give off energy as light). Figure 7.3 Exothermic Reactions. |
SciQ | SciQ-6522 | molecular-biology, chromosome, meiosis, mitosis
Which flags are used by the enzymes in the process of making the
centromere to tell them that it is the right spot
There are some centromere associated repeats in the DNA which mark the site for centromere assembly. There is no particular consensus sequence of this repeat. However, this study says that in certain cases stable chromosomes are formed in the absence of centromeric repeats.
are the sister chromatids physically intertwined around each other for
the purpose of joining, or are they simply adjacent?
They are joined by proteins called cohesins. Cohesins looks like rings which form around the sister chromatids. During anaphase, the anaphase promoting complex (APC) activates an enzyme called separase, which in turn degrades cohesin.
what in the centromeres do the spindle fibres attach to, and how do
the tips of the growing fibres notice it to head it its general
direction?
Centromeres serve as a site for the assembly of kinetochore. Kinetochore is a multi-protein complex which forms contact with the spindle fibres (specifically, K-fibres. Refer this previous post). An essential component of kinetochore is the motor protein dynein which makes the kitetochore to crawl along the spindle fibres, towards the pole. The wikipedia article on kinetochore is quite descriptive and you can refer that for details.
The following is multiple choice question (with options) to answer.
Spindle fibers pull what apart in anaphase i? | [
"known chromosomes",
"True Chromosomes",
"risk chromosomes",
"linked chromosomes"
] | D | In anaphase I, the spindle fibers pull the linked chromosomes apart. The sister chromatids remain tightly bound together at the centromere. It is the chiasma connections that are broken in anaphase I as the fibers attached to the fused kinetochores pull the homologous chromosomes apart (Figure 7.5). In telophase I, the separated chromosomes arrive at opposite poles. The remainder of the typical telophase events may or may not occur depending on the species. In some organisms, the chromosomes decondense and nuclear envelopes form around the chromatids in telophase I. Cytokinesis, the physical separation of the cytoplasmic components into two daughter cells, occurs without reformation of the nuclei in other organisms. In nearly all species, cytokinesis separates the cell contents by either a cleavage furrow (in animals and some fungi), or a cell plate that will ultimately lead to formation of cell walls that separate the two daughter cells (in plants). At each pole, there is just one member of each pair of the homologous chromosomes, so only one full set of the chromosomes is present. This is why the cells are considered haploid—there is only one chromosome set, even though there are duplicate copies of the set because each homolog still consists of two sister chromatids that are still attached to each other. However, although the sister chromatids were once duplicates of the same chromosome, they are no longer identical at this stage because of crossovers. |
SciQ | SciQ-6523 | mutations, extinction, genetics
Title: Could random male-only-offspring mutation wipe out a species? If we can engineer the extinction of a whole species of mosquitos with male-only-offspring genetic mutation, how come such scenario never happened naturally in the past to other species? Or has it? It has happened the R2D2 mutation in mice is famous for it, the mutation prevents or drastically reduces female offspring. It can wipe out entire populations when it shows up, it doesn't wipe out the species becasue there are frankly too many mice, separated by too much distance, while breeding too fast for the gene to spread fast enough before the population crashes. If mice happened to live on only one island however they would be gone. These events are called selfish sweeps or selective sweeps that result from a transmission bias in a gene.
the opposite can also occur (female only) however this is slighly less likely to lead to instant extinction since a possible out exists. Lepidodactylus lugubris(a gecko) being a famous example and is a female only species that reproduced through parthenogenesis. These types of species are exceedingly rare and have problems however as they are very vulnerable to disease since they have low diversity. Species like this are driven extinct indirectly by the mutation that led to a female only species as their diversity sufferers drastically so disease or environmental change can wipe them out more easily.
The following is multiple choice question (with options) to answer.
What type of mutations cannot be passed on to offspring? | [
"instructional mutations",
"symbiotic mutations",
"somatic mutations",
"functional mutations"
] | C | Somatic mutations occur in other cells of the body. These mutations may have little effect on the organism because they are confined to just one cell and its daughter cells. Somatic mutations cannot be passed on to offspring. |
SciQ | SciQ-6524 | biochemistry, metabolism
The second system, glycolysis, simply refers to the breakdown of carbohydrates (e.g. glucose) to resynthesize ATP from the energy stored in those carbohydrates. Your muscles contain a buffer of glycogen, approx. 300~ gr for the average Joe (give or take). The glycogen can be broken down to glucose-6-phosphate, which can then enter glycolysis. The glucose-6-phosphate is broken down to 2 pyruvate and yields 3 ATP netto (2 when derived from glucose, rather than glycogen, due to a first enzymatic step which requires 1 ATP). The enzymatic steps of glycolysis are controlled by ATP, AMP, ADP and other factors, factually integrating the energy status of the muscle (primarly through allosteric regulation of enzymes, especially phosphofructokinase).
The third system, the oxidative system, refers to the breakdown of carbohydrates and fatty acids, requiring oxygen to 'burn' them (citric acid cycle). The yield of this is much higher than for glycolysis, but the process is way slower.
In essence, all are regulated by the concentration of substrates and products, as well as through allosteric regulation (binding of a molecule at a different site, inhibiting or activating the enzyme, often by intermediates of the pathways themselves). Additionally, there is some long-term regulation through gene expression (e.g. up- or down-regulating expression of genes involved in these pathways), mostly by hormones.
Edit:
Well, I guess this is described in any basic biochemistry book (I'm very fund of the book 'Fundamentals of Biochemistry: Life at the Molecular Level'). If you want to see a description of these energy systems in a more exercise related context (since you were aiming at myocytes) I suggest reading Strength and Condition: Biological Principles and Practical Applications from Marco Cardinale et al., and the NSCA book Essentials of Strength and Conditioning.
The following is multiple choice question (with options) to answer.
What is the process in which cells break down glucose, release the stored energy, and use it to make atp | [
"photosynthesis",
"electromagnetic respiration",
"reproduction",
"cellular respiration"
] | D | Cellular respiration is the process in which cells break down glucose, release the stored energy, and use it to make ATP. The process begins in the cytoplasm and is completed in a mitochondrion. |
SciQ | SciQ-6525 | thermodynamics
Title: Does a gas condenses above its dew point? We all know that at temperatures much below the boiling point, evaporation occurs and liquid/vapor equilibrium exists.
So if we have steam at temperature greater than dew point, does it undergoes condensation at that temperature? Let's, for simplicity, consider a closed container with a liquid. In such closed system, evaporation and condensation happen simultaneously.
The rate of evaporation increases with temperature. The rate of condensation, which happens when vapor molecules hit the surface of the liquid, depends on the vapor pressure.
At equilibrium, the rates of evaporation and condensation are the same and the temperature is a dew point, by definition.
If the temperature is raised above that point, the rate of evaporation will exceed the rate of condensation, but, the condensation will still occur. This will continue until the new equilibrium is achieved, with the new temperature becoming a new dew point.
So, for a closed system, condensation does happen at temperatures above the dew point.
In an open environment, when the vapor does not come in contact with liquid, the condensation, generally, should not occur above the dew point.
The following is multiple choice question (with options) to answer.
Dew point is the temperature at which what occurs? | [
"precipitation",
"combustion",
"fermentation",
"condensation"
] | D | When air is very humid, it doesn’t have to cool very much for water vapor in the air to start condensing. The temperature at which condensation occurs is called the dew point. The dew point varies depending on air temperature and moisture content. It is always less than or equal to the actual air temperature, but warmer air and moister air have dew points closer to the actual air temperature. That’s why glasses of cold drinks “sweat” more on a hot, humid day than they do on a cool, dry day. For more details on the dew point, read the short article at this URL: http://www. kidsgeo. com/geography-for-kids/0108-dew-point. php. |
SciQ | SciQ-6526 | endocrinology, glucose, homeostasis, insulin, hypothalamus
Title: Role of the Hypothalmus in the control of Blood Sugar In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process? Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
The following is multiple choice question (with options) to answer.
In what type of diabetes can the pancreas still make insulin, but the cells of the body cannot use it efficiently? | [
"type 1 diabetes",
"type 3 diabetes",
"type A diabetes",
"type 2 diabetes"
] | D | Type 2 diabetes occurs when body cells are no longer sensitive to insulin. The pancreas may still make insulin, but the cells of the body cannot use it efficiently. Being overweight and having high blood pressure increase the chances of developing type 2 diabetes. Type 2 diabetes usually develops in adulthood, but it is becoming more common in teens and children. This is because more young people are overweight, due to a high sugar and fat diet, now than ever before. |
SciQ | SciQ-6527 | meteorology, climate-change, gas, pollution
If you are interested in Greenhouse Gases (e.g. methane, carbon dioxide, CFCs, nitrous oxide), the EPA has a separate site for those emissions since they are not part of the same regulatory framework http://www.epa.gov/climatechange/ghgemissions/ . Greenhouse gases typically do not cause adverse health effects for plants or animals on land. However, they have long-term radiative effects (e.g. the greenhouse effect) because they stay in the atmosphere for many years and trap infrared light. These long-term radiative effects are what can change climate and consequently land cover. Furthermore, most of the excess carbon is absorbed by the ocean, which creates carbonic acid. Increased acidity of the ocean causes severe problems for marine ecosystems.
The EPA states that in 2012 the CO2 equivalent GHG emissions for the USA by sector was:
The following is multiple choice question (with options) to answer.
What are the two classifications of factors in the environment that affect organisms? | [
"Antibiotick and abiotic",
"biotic and abiotic",
"rotational and abiotic",
"shear and abiotic"
] | B | Organisms depend on their environment to meet their needs, so they are greatly influenced by it. There are many factors in the environment that affect organisms. The factors can be classified as either biotic or abiotic. |
SciQ | SciQ-6528 | thermodynamics, planets, atmospheric-science, rocket-science, fusion
Adding ever more CO2 to an atmosphere has a logarithmic effect. Adding more CO2 to Mars' already saturated atmosphere won't have much of an effect.
Mars low gravitational acceleration means the dry adiabatic lapse rate on Mars is less than half that on Earth. Greenhouse gases move an atmosphere away from an isothermal atmosphere toward an adiabatic atmosphere. Mars thin atmosphere and low lapse rate alone explain most of why the greenhouse effect on Mars is significantly less than that on Earth.
There are two bands in the thermal infrared where CO2 is a very good absorber/emitter of radiation. One peaks at Earth equatorial temperatures (Mars doesn't get anywhere near that hot), the other peaks at Earth polar temperatures (that's Mars). That lower peak means that, except for polar regions, Earth's middle troposphere to upper stratosphere are extremely opaque to infrared radiation. Mars atmosphere on the other hand gets increasingly more transparent in the infrared with increased altitude.
Nukes could help warm Mars. Mars' energy budget varies considerably with Mars' weather. Mars occasionally suffers planet-wide dust storms. While those dust storms increase Mars' albedo, they change the energy flux to and from the surface by more than enough to compensate for this lost incoming energy. If the goal is to heat Mars up, it would make a lot more sense to nuke Mars' equatorial regions instead of its poles. We'd have to do this on a regular basis to have any effect. Whether or not this is a good idea is a different question.
The following is multiple choice question (with options) to answer.
What do increasing greenhouse gas concentrations in the air do to the earth's temperature? | [
"stable it",
"Lower it",
"raise it",
"Pollute"
] | C | |
SciQ | SciQ-6529 | population-genetics, molecular-evolution, microbiome, quantitative-genetics
Microbiome members are often interdependent
As hinted at in the question update, bacteria display a type of community altruism, where an individual cell with a specific gene can influence the fitness of neighboring cells that lack the gene. For an example, see my answer to Will all bacteria become resistant against all antibiotics in the long term? concerning secreted β-lactamases.
Therefore, spatial association is an added factor when considering population dynamics of a genetically heterogeneous bacterial species. Some methods that address cell-cell spatial proximity in microbiomes include sequencing of cryofractured fragments 17 and probe-based spectral imaging.18 Even if microbes are not spatially associated, different microbes may play complementary roles in the iterative metabolism of large carbohydrates into small metabolites.19,20
Surely, this discussion is incomplete, though I hope my answer has given you the footing you need to continue your own exploration to find the appropriate resources for your research. For a more in-depth discussion of the points I've addressed here, see What Is Metagenomics Teaching Us, and What Is Missed?,21 particularly the sections titled Strain-Level Analyses and Ecoevolutionary Modeling.
The following is multiple choice question (with options) to answer.
What is the name of a microorganism that is considered important for living resources in all ecosystem? | [
"bacteria",
"protozoa",
"archaea",
"pathogens"
] | A | Microorganisms such as bacteria are important living resources in all ecosystems. They recycle nutrients and other matter. |
SciQ | SciQ-6530 | 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.
What bone cell is responsible for forming new bone and is found in the growing portions of bone, including the periosteum and endosteum? | [
"epithelial",
"congenial",
"osteoblast",
"fibroblasts"
] | C | The osteoblast is the bone cell responsible for forming new bone and is found in the growing portions of bone, including the periosteum and endosteum. Osteoblasts, which do not divide, synthesize and secrete the collagen matrix and calcium salts. As the secreted matrix surrounding the osteoblast calcifies, the osteoblast become trapped within it; as a result, it changes in structure and becomes an osteocyte, the primary cell of mature bone and the most common type of bone cell. Each osteocyte is located in a space called a lacuna and is surrounded by bone tissue. Osteocytes maintain the mineral concentration of the matrix via the secretion of enzymes. Like osteoblasts, osteocytes lack mitotic activity. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi (singular = canaliculus), channels within the bone matrix. If osteoblasts and osteocytes are incapable of mitosis, then how are they replenished when old ones die? The answer lies in the properties of a third category of bone cells—the osteogenic cell. These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide. Immature osteogenic cells are found in the deep layers of the periosteum and the marrow. They differentiate and develop into osteoblasts. The dynamic nature of bone means that new tissue is constantly formed, and old, injured, or unnecessary bone is dissolved for repair or for calcium release. The cell responsible for bone resorption, or breakdown, is the osteoclast. They are found on bone surfaces, are multinucleated, and originate from monocytes and macrophages, two types of white blood cells, not from osteogenic cells. Osteoclasts are continually breaking down old bone while osteoblasts are continually forming new bone. The ongoing balance between osteoblasts and osteoclasts is responsible for the constant but subtle reshaping of bone. Table 6.3 reviews the bone cells, their functions, and locations. |
SciQ | SciQ-6531 | human-biology, cell-biology, tissue, tissue-repair
Shining light on skin pigmentation: the darker and the brighter side
of effects of UV radiation.
Melanocyte biology and skin pigmentation.
Melanosome Degradation: Fact or Fiction
The following is multiple choice question (with options) to answer.
Individuals with what condition experience depigmentation that results in lighter colored patches of skin? | [
"dementia",
"psoriasis",
"vitiligo",
"eczema"
] | C | Figure 5.10 Vitiligo Individuals with vitiligo experience depigmentation that results in lighter colored patches of skin. The condition is especially noticeable on darker skin. (credit: Klaus D. Peter). |
SciQ | SciQ-6532 | meteorology, atmosphere, carbon, co2, rain
Bear in mind that this assumes an enormous rainfall intensity, 100% CO2 saturation of the water and equilibrium chemical dynamics. After the raindrops hit the ground at least half of it will immediately re-evaporate back into the air, leaving, at absolute most, about 3% of the atmospheric CO2 leached out of the atmosphere that will be available to react with the soil, rock or biosphere. Also consider that this is but one of several important processes affecting CO2 transience, such as photosynthesis, respiration, volcanism, industrial pollution, etc. So the CO2 estimates that you read about are average values. Advection and turbulent air mixing should ensure that the CO2 regains approximately normal concentration within an hour or two after rainfall.
The following is multiple choice question (with options) to answer.
What do decomposers release back to the environment after they break down the remains and other wastes? | [
"carbon monoxide",
"nematodes",
"simple inorganic molecules",
"unrefined waste"
] | C | When organisms die, they leave behind energy and matter in their remains. Decomposers break down the remains and other wastes and release simple inorganic molecules back to the environment. Producers can then use the molecules to make new organic compounds. The stability of decomposers is essential to every ecosystem. Decomposers are classified by the type of organic matter they break down:. |
SciQ | SciQ-6533 | 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 are the areas between cells that either allow or prevent the movement of materials called? | [
"junctions",
"corners",
"sections",
"receptors"
] | A | Junctions are areas between cells that either allow or prevent the movement of materials. Junctions are usually composed of numerous proteins, forming a large molecular complex. Gap junctions, desmosomes and tight junctions are three examples of junctions. |
SciQ | SciQ-6534 | metabolism, nutrition, digestive-system
Title: Do I have to chew for digestion to kick in? Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"? If you had to chew to digest, then beverages like sugary sodas would never be digested or provide calories or nutrients, as you (generally) don't chew when you drink them. No, chewing is not required for digestion or nutrient absorption. Chewing is important when eating solid foods, as the chewing action breaks down and begins to solublize the food, and stimulates the production of saliva, which contains enzymes that begin to break down the food prior to digestion in the stomach and intestines.
The following is multiple choice question (with options) to answer.
Arguably the most important ingredient in saliva for digestion is a type of what, which initiates the breakdown of carbohydrates? | [
"genes",
"enzyme",
"amino",
"fatty"
] | B | Saliva Saliva is essentially (95.5 percent) water. The remaining 4.5 percent is a complex mixture of ions, glycoproteins, enzymes, growth factors, and waste products. Perhaps the most important ingredient in salvia from the perspective of digestion is the enzyme salivary amylase, which initiates the breakdown of carbohydrates. Food does not spend enough time in the mouth to allow all the carbohydrates to break down, but salivary amylase continues acting until it is inactivated by stomach acids. Bicarbonate and phosphate ions function as chemical buffers, maintaining saliva at a pH between 6.35 and 6.85. Salivary mucus helps lubricate food, facilitating movement in the mouth, bolus formation, and swallowing. Saliva contains immunoglobulin A, which prevents microbes from penetrating the epithelium, and lysozyme, which makes saliva antimicrobial. Saliva also contains epidermal growth factor, which might have given rise to the adage “a mother’s kiss can heal a wound. ” Each of the major salivary glands secretes a unique formulation of saliva according to its cellular makeup. For example, the parotid glands secrete a watery solution that contains salivary amylase. The submandibular glands have cells similar to those of the parotid glands, as well as mucus-secreting cells. Therefore, saliva secreted by the submandibular glands also contains amylase but in a liquid thickened with mucus. The sublingual glands contain mostly mucous cells, and they secrete the thickest saliva with the least amount of salivary amylase. |
SciQ | SciQ-6535 | organic-chemistry, bond, lewis-structure
Title: How do I draw a Lewis diagram after drawing the orbital diagram The question says "Oxygen can form compounds with every period 3 element except argon. Determine which would be ionic or covalent compounds, and draw Lewis diagrams to represent each one." I started with oxygen and fluorine and I'm having a hard time. I don't know if there should be lone pairs, double bonds, or even lone electrons.Here's my attempt at it: First of all, oxygen follows "the octet rule", which states that certain elements are stable when they have 8 electrons around them. Now this rule is by no means absolute, does not work with d orbitals onward, and should only be used in very elementary chemistry, unless you actually know its cause. In the case of that picture, you are missing 2 non-bonding electrons on the oxygen.
Remember that a covalent bond means that electrons are being shared by the 2 atoms. In the case of O and F, the pauling electronegativities are quite similar, so the electrons are actually "shared".
However, when you try to put oxygen together with group 1 or group 2 elements, you will find very different electronegativity values. What this means is that oxygen has much more affinity to electrons than Na or Mg. The rule I was taught at school was that a difference of 2 or more in electronegativity between the elements results in ionic compounds, meaning the oxygen "steals" the electrons, becoming a negative anion, whereas Na for example becomes a positive one.
The last guideline you should take into account, is that an atom tends to lose or gain electrons because it "likes" to have its most outer shell full. So when you look at the principal quantum number ($n$) of the most outer shell, you should create compounds where it is full. In the case of oxygen, that quantum number is $2$, which can have 8 electrons, hence the octet rule. For Na, you have 1 electron in $n=3$, so if the atom looses that electron, it will become more stable, therefore we have $\ce{Na+}$.
The following is multiple choice question (with options) to answer.
What element can form two different compounds with oxygen? | [
"carbon",
"dioxide",
"H20",
"hydrogen"
] | A | Carbon can form two different compounds with oxygen. |
SciQ | SciQ-6536 | biochemistry, chemical-biology
Title: pH effect in the hydrophobic interactions between two polypeptide chains The rise in pH can change the protein conformation by changing the ionic interactions and hydrogen bonds between two polypeptide chains. This is a fact that I understand very well because the change in amino-acid ionization with pH. I would like to know if by changing the pH value the hydrophobic interactions between two chains can also be changed. If yes, what is the mechanism?
Article: a pH Induced increase in hydrophobicity... Here is one possible mechanism:
In tightly folded, compact, "globular" protein structures, the most hydrophobic bits of the protein tend to be in the core of the structure, away from the surface.
If the pH changes, then by mechanisms you mention in your question, this structure can be disrupted. If it is side chain interactions among surface-oriented, polar residues that "hold together" the globular structure, then a pH change can disrupt those interactions, allowing the previously isolated hydrophobic "core" to become exposed. This core can now bind more surfactant molecules, aggregate with itself, or do any number of other "hydrophobic" things.
The following is multiple choice question (with options) to answer.
Each protein has its own unique sequence and shape held together by chemical interactions. if the protein is subject to changes in temperature, ph, or exposure to chemicals, the protein structure may change, losing its shape in what is known as this? | [
"extraction",
"gastrulation",
"fermentation",
"denaturation"
] | D | Each protein has its own unique sequence and shape held together by chemical interactions. If the protein is subject to changes in temperature, pH, or exposure to chemicals, the protein structure may change, losing its shape in what is known as denaturation as discussed earlier. Denaturation is often reversible because the primary structure is preserved if the denaturing agent is removed, allowing the protein to resume its function. Sometimes denaturation is irreversible, leading to a loss of function. One example of protein denaturation can be seen when an egg is fried or boiled. The albumin protein in the liquid egg white is denatured when placed in a hot pan, changing from a clear substance to an opaque white substance. Not all proteins are denatured at high temperatures; for instance, bacteria that survive in hot springs have proteins that are adapted to function at those temperatures. |
SciQ | SciQ-6537 | evolution, mycology
Title: Why are some fungi poisonous? There are many poisonous fungi in nature. For example Amanita Phalloides.
What reasons could a fungus need poison for? Some species, like venomous snakes, use poison to kill other species as prey. But what about fungi? I can't think of any purpose for poison in fungi. If poison has no real function in fungi shouldn't evolution get rid of it? The same reason some plants are poisonous: to stop animals from eating them.
The visible part of the fungus is called, rather misleadingly, the fruiting body. It exists to produce and spread spores and thus produce the next fungal generation. Getting eaten, rather obviously, inhibits its ability to do this. Being poisonous discourages animals from eating the fruiting body and thus permits it to complete its life cycle.
The following is multiple choice question (with options) to answer.
Because they can cause diseases in plants, some parasitic fungi are considered what? | [
"toxic",
"pathogenic",
"bacterial",
"viral"
] | B | |
SciQ | SciQ-6538 | units, viscosity
Title: A viscosity unit Does the viscosity unit "$\mathrm{ps}$" exist or is it a misprint and refers to poise "$\mathrm{P}$"? Thank you
A liquid of $0.014\,\mathrm{ps}$ viscosity and $1.4\,\mathrm{g/cm^3}$ density circulates through a $3.14\,\mathrm{cm^2}$ section pipe with a flow rate of $0.352\,\mathrm{liters/s}$. Determine the Reynolds number of the flow and decide if the liquid is flowing in laminar or turbulent regime. Sun: $Re = 22415$; turbulent regime The two common units for viscosity are the poise (symbol $\rm{P}$) and the Pascal second (symbol $\rm{Pa.s}$). The poise is the cgs unit while the Pascal second is the SI unit.
Given that the question appears to be using the cgs system I would guess that ps is being used as an abbreviation for poise.
The following is multiple choice question (with options) to answer.
What is another common term for single-unit smooth muscle? | [
"lateral muscle",
"energies muscle",
"visceral muscle",
"abnormal muscle"
] | C | Smooth muscle is organized in two ways: as single-unit smooth muscle, which is much more common; and as multiunit smooth muscle. The two types have different locations in the body and have different characteristics. Single-unit muscle has its muscle fibers joined by gap junctions so that the muscle contracts as a single unit. This type of smooth muscle is found in the walls of all visceral organs except the heart (which has cardiac muscle in its walls), and so it is commonly called visceral muscle. Because the muscle fibers are not constrained by the organization and stretchability limits of sarcomeres, visceral smooth muscle has a stress-relaxation response. This means that as the muscle of a hollow organ is stretched when it fills, the mechanical stress of the stretching will trigger contraction, but this is immediately followed by relaxation so that the organ does not empty its contents prematurely. This is important for hollow organs, such as the stomach or urinary bladder, which continuously expand as they fill. The smooth muscle around these organs also can maintain a muscle tone when the organ empties and shrinks, a feature that prevents “flabbiness” in the empty organ. In general, visceral smooth muscle produces slow, steady contractions that allow substances, such as food in the digestive tract, to move through the body. Multiunit smooth muscle cells rarely possess gap junctions, and thus are not electrically coupled. As a result, contraction does not spread from one cell to the next, but is instead confined to the cell that was originally stimulated. Stimuli for multiunit smooth muscles come from autonomic nerves or hormones but not from stretching. This type of tissue is found around large blood vessels, in the respiratory airways, and in the eyes. |
SciQ | SciQ-6539 | -plane. The horizontal distance the projectile travels is called the range. The projectile covers the same horizontal distance reaching its maximum height as it does falling from its maximum height back to the ground. Sqrt((x * x) + (y * y)); This is the equation of a parabola which is symmetric about the y-axis. 80665 m/s²). 95m (the intial horizontal displacement is 0), the angle of release is 35 degrees and the range of the projectile (or the horizontal displacement at impact) is 90. However, this takes advantage of the fact that horizontally, acceleration is Characteristics of a Projectile's Trajectory · Horizontal and Vertical Components The above equations work well for motion in one-dimension, but a projectile is A projectile is an object that is given an initial velocity, and is acted on by gravity. Note: Use g = 9. However, the distance it travels vertically (on the Y-axis) is given as y = vtsinΦ – (½)gt². The time for projectile motion is completely determined by the vertical motion. Trajectory of projectile motion when u is intial speed inclined Ф angle with horizontal the equation of projectile is : y = xTanФ - gx²/ 2u²Cos²Ф and the given equation is : y = √3x - gx²/2 on comparing both the equations ,we get TanФ = √3 so, Ф = 60° HENCE, the angle of projectile is 60° and 2u²Cos²Ф = 2 so u²Cos²Ф = 1 u²cos²60° = 1 Horizontal distance traveled Horizontal range = OR = s x (t = t f) g u g u u θ θ θ sin2 cos 2 sin 2 = = (8) Half horizontal range = OA = g u 2 2sin2θ (9) By using different angle of projectile θ, we can change the horizontal distance OR. Objects such as a basketball are released into the air at an angle and as such have vertical and horizontal velocity. Equation 9 thus becomes: Equation 10: Now we can use Equations 8 and 10 to plot the motion of a projectile in the (x,y) plane. Air Resistance. Projectile motion is considered here with the following approximations: 1. x = distance travelled by the object in horizontal direction in time t y = distance travelled by the object in vertical direction in time t Now the velocity
The following is multiple choice question (with options) to answer.
What is the term for the horizontal displacement of a projectile from its starting point? | [
"type",
"produce",
"Distance",
"range"
] | D | In projectile motion, the horizontal displacement of an object from its starting point is called its range. |
SciQ | SciQ-6540 | endocrinology
Excitement or stress response, including fast heart rate and breathing and anxiety: short term response: adrenaline; long-term response: cortisol
Appetite: ghrelin, leptin, adiponectin, cholecystokinin, insulin, glucagon-like peptide, gastrointestinal peptide...
Sexual drive: sex hormones, mainly testosterone and estradiol
Sleepiness: melatonin, cortisol
Depression: cortisol, sex hormones (mainly in women)
The point of this answer is to show that some of your feelings can be simply affected by hormones, which are note some ultimate forces, and that being aware of that can help you to control them to some extent.
The following is multiple choice question (with options) to answer.
What types of stimuli control endocrine activity? | [
"temperature and light",
"chemical and neural",
"light and pressure",
"pressure and chemical"
] | B | Role of Endocrine Gland Stimuli Reflexes triggered by both chemical and neural stimuli control endocrine activity. These reflexes may be simple, involving only one hormone response, or they may be more complex and involve many hormones, as is the case with the hypothalamic control of various anterior pituitary–controlled hormones. Humoral stimuli are changes in blood levels of non-hormone chemicals, such as nutrients or ions, which cause the release or inhibition of a hormone to, in turn, maintain homeostasis. For example, osmoreceptors in the hypothalamus detect changes in blood osmolarity (the concentration of solutes in the blood plasma). If blood osmolarity is too high, meaning that the blood is not dilute enough, osmoreceptors signal the hypothalamus to release ADH. The hormone causes the kidneys to reabsorb more water and reduce the volume of urine produced. This reabsorption causes a reduction of the osmolarity of the blood, diluting the blood to the appropriate level. The regulation of blood glucose is another example. High blood glucose levels cause the release of insulin from the pancreas, which increases glucose uptake by cells and liver storage of glucose as glycogen. An endocrine gland may also secrete a hormone in response to the presence of another hormone produced by a different endocrine gland. Such hormonal stimuli often involve the hypothalamus, which produces releasing and inhibiting hormones that control the secretion of a variety of pituitary hormones. In addition to these chemical signals, hormones can also be released in response to neural stimuli. A common example of neural stimuli is the activation of the fight-or-flight response by the sympathetic nervous system. When an individual perceives danger, sympathetic neurons signal the adrenal glands to secrete norepinephrine and epinephrine. The two. |
SciQ | SciQ-6541 | asteroids, comets, extinction
This is somewhat doable, but quickly get complex (different populations, orbits are not actually evenly distributed, etc.) A better approach may simply be to look at the past impacts causing extinctions! Depending on how you count, there has been one known mass extinction due to impacts since the Cambrian 538.8 mya, so the rate might be on the order of $2\cdot 10^{-9}$ per year. But that likely leaves out a fair number of minor extinctions. If we assume all Big 5 were due to impacts the rate becomes $9\cdot 10^{-9}$ per year.
Incidentally, to get these values in the above formula for the assumed values, $N$ should be in the range 0.2 to 1.
Obviously this can be improved: we can use statistical modelling to get error bars, we can use the known size distribution of asteroids (a power law) to estimate the fraction of Earth-crossers and long-periodic comets that could be bad and their inflow rate, and so on. But that misses the Drake equation approach of trying to find a quick-and-dirty model that shows the key variables we care about and might want to estimate.
The following is multiple choice question (with options) to answer.
What events, resulting in death of over half of animal species, have occurred on earth at least five times in the past 540 million years? | [
"mass migrations",
"spontaneous mutations",
"mass extinctions",
"microevolutions"
] | C | Since life began on Earth, there have been several major mass extinctions. If you look closely at the geological time scale, you will find that at least five major mass extinctions have occurred in the past 540 million years. In each mass extinction, over 50% of animal species died. The total number of mass extinctions could be as high as 20. |
SciQ | SciQ-6542 | agriculture
The primary cereals for making bread are wheat and rye, while barley and oats may be mixed in. Historically significant portions of the rural population of Europe were sustained by cereal-based food in the form of gruel and porridge rather than by bread, especially prior to the introduction of the potato. Barley can be consumed in the form of pearl barley and groats and oats in the form of oatmeal. Especially in cool and humid climates not very suitable for cultivating wheat and rye, oats were once commonly cultivated and consumed. When Samuel Johnson wrote his dictionary, he famously defined oats as: "A grain which in England is generally given to horses, but in Scotland supports the people." A major historical and modern use of barley has been as malted barley, the main ingredient in beer brewing.
In the case of Finland it is interesting to note how late the transition from slash-and-burn agriculture to the use of permanent fields occurred. According to Teija Alenius, Environmental change and anthropogenic impact on lake sediments during the Holocene in the Finnish − Karelian inland area, Ph.D. thesis, University of Helsinki, 2007 (online)
The following is multiple choice question (with options) to answer.
What is most of the water used in agriculture used for? | [
"cleaning",
"sowing",
"construction",
"irrigation"
] | D | Many crops are grown where there isn’t enough rainfall for plants to thrive. For example, crops are grown in deserts of the American southwest. How is this possible? The answer is irrigation. Irrigation is any way of providing extra water to plants. Most of the water used in agriculture is used for irrigation. Livestock also use water, but they use much less. |
SciQ | SciQ-6543 | cholesterol
Some LDL cholesterol circulating through the bloodstream tends to deposit in the walls of arteries. This process starts as early as childhood or adolescence.
White blood cells swallow and try to digest the LDL, possibly in to digest the LDL, possibly in an attempt to protect the blood vessels.
In the process, the white blood cells convert the LDL to a toxic (oxidized) form.
More white blood cells and other cells migrate to the area, creating steady low steady low-grade inflammation in the artery wall.
Over time, more LDL cholesterol and cells collect in the area. The ongoing process creates a bump in the artery wall called a plaque. The plaque is made of cholesterol, cells, and debris.
The process tends to continue, growing the plaque and slowly blocking the artery.
There is a good overview of the general physiology here in Robbins The Pathologic Basis of Disease. Chapter 5, Genetic Disorders, reviews the physiology, and the relevance to disease, in the section on Familial Hypercholesterolemia. The review is relevant to hypercholesterolemia in general.
The following is multiple choice question (with options) to answer.
What is a collection of fibrin, platelets, and erythrocytes that has accumulated along the lining of a blood vessel called? | [
"clots",
"embolus",
"atherosclerosis",
"thrombus"
] | D | thrombosis, can be caused by excessive numbers of platelets. A thrombus is a collection of fibrin, platelets, and erythrocytes that has accumulated along the lining of a blood vessel, whereas an embolus is a thrombus that has broken free from the vessel wall and is circulating in the bloodstream. |
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