source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-4644 | centrifugal-force, centripetal-force
Similarly, a centripetal force is needed to make you go in a circle. If you sit there, you have to apply a force outwards which we call centrifugal force, to use Newton's laws.
Centripetal force is a force which provides acceleration towards centre, say, Tension while moving the object round with string. So if, you apply $F=ma$ from the revolving object, you have to add centrifugal force as the object is at rest wrt itself.
You can explain what you experience while turning due to you inertia which resists you change in motion.
The following is multiple choice question (with options) to answer.
Forces which cause objects to turn around continuously in a circle are known as? | [
"centripetal forces",
"frictional forces",
"hydrodynamic forces",
"tension forces"
] | A | In the absence of a net force, objects move in a straight line. If they turn — that is, if their velocity changes, even only in direction — there must be an applied force. Forces which cause objects to turn around continuously in a circle are known as centripetal forces. When an object moves in a circle its velocity at any particular instant points in a direction tangent to the circle. The acceleration points towards the center of the circle, and so does the force acting on it. This is only natural, when you think about it — if you feel a force pushing you towards your left as you walk forward, you will walk in a circle, always turning left. |
SciQ | SciQ-4645 | 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.
Why is a synthetic diamond not considered a mineral? | [
"interactions must be created naturally",
"fluctuations must be created naturally",
"Minerals must not occur naturally.",
"minerals must be created naturally"
] | D | Could a mineral be made by a process that was not natural? People make gemstones in a laboratory. Synthetic diamond is a common one. But that stone is not a mineral. That's because a mineral must be created by natural processes. This is part of the definition of a mineral. |
SciQ | SciQ-4646 | electrical-engineering, heating-systems, heat-treatment
Title: Heating tape that has leads like picture below Does anyone know where I can find Heating tape that has these same leads or know what they are called? It is meant to be plugged into the second picture attatched. When searching for 1100 watt heating tape, a number of returns match almost exactly the image you've provided. A few of the manufacturers provide NEMA separable molded plugs and also offer bare leads. The bare leads would be useful in this case, as you can add your own 90° banana plugs.
To locate the correct plug, I used "right angle enclosed banana plug" as the search term. The image and source information came from Zoro online. I had better returns using shrouded in place of enclosed. Many sources. Be sure to check the current draw for the tape you'll use and the connector you'll select.
The following is multiple choice question (with options) to answer.
What type of plug is generally used on metal appliances? | [
"5 prong",
".2 prong",
"4 prong",
"3 prong"
] | D | A three-prong plug is generally used on metal appliances. The two flat prongs carry current to and from the appliance. The round prong is for safety. It connects with a wire inside the outlet that goes down into the ground. If any stray current leaks from the circuit or if there is a short circuit, the ground wire carries the current into the ground, which harmlessly absorbs it. |
SciQ | SciQ-4647 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What term describes the ability of matter to combine chemically with other substances? | [
"reactivity",
"oxidation",
"permeability",
"Diffusion"
] | A | Reactivity is the ability of matter to combine chemically with other substances. For example, iron is highly reactive with oxygen. When it combines with oxygen, it forms the reddish powder called rust (see Figure below ). Rust is not iron but an entirely different substance that consists of both iron and oxygen. |
SciQ | SciQ-4648 | waves
Title: Is wave motion the combined motion of the disturbance and the medium? Using a textbook slinky as an example, if the disturbance propagates through the slinky from left to right and the particles of the slinky vibrate up and down, does that mean 'wave motion' is also associated with the medium? Since the motion of the wave that we perceive is the combined motion of the disturbance and the medium? This answer is maybe not the most straightforward satisfactory answer to your stated question, but I think it anticipates ways of thinking that are used in more advanced areas of physics.
There are two pictures of what a wave is.
A wave is coherent motion in a medium; as time progresses energy moves through the medium and vibrations occur in different locations.
A wave is a propagating disturbance. It is not made of anything, the word "wave" refers a disturbance which propagates energy from one place to another.
Your question kind of implies that a wave is some combination of 1 and 2. I would say that either 1 or 2 are valid pictures, but you should treat them as distinct pictures of the same physical phenomenon and not reason about both simultaneously.
The advantage of the first picture is that it gives you a clear mechanical model of what is going on at a fundamental level; if you zoom in there are particles in the material, and the particles are oscillating back and forth in tandem -- that coherent motion is a wave. However, the disadvantage is that wave phenomena occur in many circumstances, and there are features of any particular example that will not generalize and can lead you astray if you take them too seriously. For example, light traveling in vacuum cannot be accurately visualized as motion of particles.
The advantage of the second picture is that it is more abstract and general -- wave phenomena occur in all kinds of materials, and so there is no need to specify which specific material you are thinking of, because we can make very general statements about waves that apply to any material. The disadvantage is that it can be hard to wrap your head around a disturbance without a medium, and also sometimes trying to be too general means you miss special aspects of the particular situation you might be interested in (for example, cool behavior like solitons can occur in water but not in light propagating in vacuum).
The following is multiple choice question (with options) to answer.
What occurs when waves interact with other waves? | [
"frequency",
"vibration",
"resurgence",
"interference"
] | D | Wave interference occurs when waves interact with other waves. Constructive interference increases wave amplitude. Destructive interference decreases wave amplitude. |
SciQ | SciQ-4649 | forces, pressure, continuum-mechanics, stress-strain
Title: Why is a force distributed over an area? Why couldn't the stress be directly equal to the force? So, my question might seem silly. I know in real life when we apply a force with our hand and push on lets say a cylinder , we know the force will be distributed over the cross section of the area, so if we had a wider area, we need more force, and if we had smaller area, then we need less force to push the cylinder a certain distance.
So its intuitive. The stress will be the force divided by the given area.
But why? like what happens at the micro-scale, and what makes the force be divided?
Thanks. Actually as @trula said the external force you apply acts only at the contact point but since all atoms are connected to each other via "interatomic forces" , your external force gets distributed all along the surface and so we need to define force per unit area viz. Stress.
The spring model of atomic structure is quite self explanatory about the interatomic force distribution.
The following is multiple choice question (with options) to answer.
What is defined in physics as the amount of force pushing against a given area? | [
"resistance",
"pressure",
"gravity",
"energy"
] | B | Particles of gas are constantly moving in all directions at random. As a result, they are always bumping into each other and other things. This is modeled in the Figure below . The force of the particles against things they bump into creates pressure. Pressure is defined in physics as the amount of force pushing against a given area. How much pressure a gas exerts depends on the number of gas particles in a given space and how fast they are moving. The more gas particles there are and the faster they are moving, the greater the pressure they create. To learn more about gas pressure and how to measure it, go to this URL: http://www. wisc-online. com/objects/ViewObject. aspx?ID=GCH5004 . |
SciQ | SciQ-4650 | thermodynamics, energy, earth, thermal-radiation
@Benjohn has given you the correct answer. Here is my take.
The ultimate heat provider of the earth ( except a small percentage of heat from the magma at the center of the earth) is the sun. It pours down at the surface about 1.2 kilowatts of energy per meter square ( which btw is directly used by solar panels). The same energy falls on the surface of the moon whose surface burns up during its daytime and freezes by black body radiation at night.
The earth is fortunate to have a gas atmosphere which mitigates the extremes of the possible temperatures that the ground would reach otherwise. An example of mitigation is what happens at the sea floor. Most of the energy is picked up by the water and the floor is kept at a steady temperature with small changes day and night in the first meters from the surface, depending on the season, radiating away with the black body radiation, but the body of water has such large heat capacity that variations are small.
The gas atmosphere is a more temperamental "blanket", its heat capacity depends on several gases , called green house gases from the bad impression that agricultural green houses work that way ( they do not, they work by inhibiting heat exchange by convection but that is another story, on which there is no controversy).
The main green house gas is water , H2O. It is worth contemplating this figure :
Solar irradiance spectrum above atmosphere and at surface. Extreme UV and X-rays are produced (at left of wavelength range shown) but comprise very small amounts of the Sun's total output power.
We see that H2O has the most absorption spectrum for infrared wavelengths, (which are the wavelengths of heat )and then comes CO2. Green house gases absorb both incoming and reflected from the surface of the earth infrared, and as most of the reflected wavelengths are in the infrared they act as a slowing down of the black body radiation that would finally leave the earth. As a blanket keeps a person warmer green house gases by playing ball with infrared radiation ( the wavelengths where heat is really transferred) keep the surface of the earth into a reasonable temperature for life, lucky us.
The following is multiple choice question (with options) to answer.
What do you call the heat below earth’s surface that can be used to produce electricity? | [
"inert energy",
"renewable energy",
"natural energy",
"geothermal energy"
] | D | Heat below Earth’s surface—called geothermal energy— can be used to produce electricity. A power plant pumps water underground where it is heated. Then it pumps the water back to the plant and uses its thermal energy to generate electricity. On a small scale, geothermal energy can be used to heat homes. Installing a geothermal system can be very costly, however, because of the need to drill through underground rocks. |
SciQ | SciQ-4651 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
How do most plants create food? | [
"electrolysis",
"photosynthesis",
"glycolysis",
"atherosclerosis"
] | B | Plants are multicellular eukaryotes. They have organelles called chloroplasts and cell walls made of cellulose. Plants also have specialized reproductive organs. Almost all plants make food by photosynthesis. Life as we know it would not be possible without plants. |
SciQ | SciQ-4652 | organic-chemistry, redox
As you can see, the ketone gets oxidised, more precisely the carbonyl carbon gets oxidised as increases its oxidation state. On the other side, the peroxide oxygens get reduced as they decrease their oxidation state.
The following is multiple choice question (with options) to answer.
In a ketone, two of which kind of groups are attached to the carbonyl carbon atom? | [
"carbon groups",
"nitrogen groups",
"ions",
"oxygen groups"
] | A | Note The carbonyl group is ubiquitous in biological compounds. It is found in carbohydrates, fats, proteins, nucleic acids, hormones, and vitamins—organic compounds critical to living systems. In a ketone, two carbon groups are attached to the carbonyl carbon atom. The following general formulas, in which R represents an alkyl group and Ar stands for an aryl group, represent ketones. |
SciQ | SciQ-4653 | parasitology
Title: Tapeworms and their effect on humans I've read that some people in some countries actually use tapeworms as a form of losing weight. What are the dangers to these people? I haven't really found much on this topic (besides popular sites) but I can summarize it here:
There are quite some tapeworms (or cestoda), I found numbers of up to 3500 species. They attach to the intestinal wall of the humans and then start to take up predigested food through their skin. With that, they reduce food from their host and start to grow, some get as long as 15 meters!
Some of the worms seem to be relatively harmless (besides stealing food), but this is more true for the first world. In poor countries, where there is not enough food, tapeworms can cause severe malnutrition.
Some tapeworms can migrate into the blood stream and from there into other tissues or organs like muscles, eye and brain. There they can cause cysts which can lead to organ failure and death.
For more information see this CDC webpage and this article: "Biochemistry and physiology of tapeworms.". This popular article is probably also interesting.
The following is multiple choice question (with options) to answer.
Tapeworms are what type of flatworms? | [
"parasitic",
"single-celled",
"symbiotic",
"endogenous"
] | A | Flatworms can be free-living or parasitic. Tapeworms are parasitic flatworms. |
SciQ | SciQ-4654 | evolution, zoology, anatomy
Title: Are the transverse septum in sharks and the diaphragm in mammals homologous structures? Are the transverse septum in sharks and the diaphragm in mammals homologous structures?
I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim. A beginning of answer here below, I hope. Please first consider that many structures are involved in the question here, the diaphragm (UBERON:0001103), the diaphragmaticus muscle (UBERON:0036071) and the septum transversum (UBERON:0004161). At Bgee (bgee.org) we aim annotating relations of similarity between anatomical structures, please have a look at our GitHub
https://github.com/BgeeDB/anatomical-similarity-annotations
We already annotated 'diaphragm' as a mammalian structure, not homologous in Amniota (please see https://raw.githubusercontent.com/BgeeDB/anatomical-similarity-annotations/master/release/similarity.tsv). In our next release, you will see the annotation for the 'diaphragmaticus muscle' which is an analog organ in Crocodylians (and Turtles) but not homologous to the mammalian diaphragm either. See here for more details about this new Uberon class:
https://github.com/obophenotype/uberon/issues/1229.
Based on the comments here above, I would say that currently we can argue that there is no evidence for a homologous relationship between the 'septum transversum' in sharks and the mammalian diaphragm. Please note that UBERON:0004161 septum transversum describes the (mammalian) embryonic structure that will give rise to the central tendon of the diaphragm, while here you are talking about a adult structure closer to a 'diaphragmaticus muscle'-like septum, as far as I understand.
But anyway thank you for your interesting question that points out a very exciting and rapidly evolving evo-devo field, as this recent paper also suggests
The following is multiple choice question (with options) to answer.
In most crustaceans, what two structures fuse to form a cephalothorax? | [
"head and thorax",
"foot and toes",
"body and shoulders",
"wing and legs"
] | A | Unlike that of the Hexapoda, the head and thorax of most crustaceans is fused to form a cephalothorax (Figure 28.40), which is covered by a plate called the carapace, thus producing a body structure of two tagma. Crustaceans have a chitinous exoskeleton that is shed by molting whenever the animal increases in size. The exoskeletons of many species are also infused with calcium carbonate, which makes them even stronger than in other arthropods. Crustaceans have an open circulatory system where blood is pumped into the hemocoel by the dorsally located heart. Hemocyanin and hemoglobin are the respiratory pigments present in these animals. |
SciQ | SciQ-4655 | evolution, neuroscience
This paper's abstract says all I was saying about the development of neurons and synapses relying on pre-existing molecules and structures:
https://pubmed.ncbi.nlm.nih.gov/2830635/
"Evolution of Neurotransmitter Receptor Systems"
What I'm looking for to find how close science is to answering your question (or if it already has) is papers looking at the phylogenetic relationships of different neurotransmitters and related molecules. That might say a lot about which ones have been used as neurotransmitters the longest. I haven't found this yet but I'll try more tomorrow when I'm not on mobile.
ETA: will re-edit this comment later, but this paper answers your question I believe, or as well as any could at present at least:
https://cichlid.biosci.utexas.edu/sites/default/files/evoneuro/files/liebeskind_et_al_2017.pdf?m=1511200627
"Evolution of Animal Neural Systems"
This paper, which is available in full and is a review paper from 2017, looks at the evolution of every aspect of animal neural systems (i.e. nervous systems mediated by neurons, a concept the paper also defines because the line is apparently blurry). One interesting aspect of it is that while you point to Cnidarians as the most "primitive" nervous systems, the paper points out the latest evidence suggests Ctenophores are the earliest branch off the animal tree, meaning nervous systems either evolved convergently, or sponges lost their nervous systems secondarily, in which case Cnidarians would lose this special status.
The paper has a section about neurotransmitters, which says the following:
The following is multiple choice question (with options) to answer.
What class of animal, including hydras and jellies, is considered the simplest to contain a nervous system? | [
"prokaryotes",
"cnidarians",
"fish",
"sponges"
] | B | |
SciQ | SciQ-4656 | everyday-chemistry, toxicity
Such oxidation reactions are catalyzed both by soluble metals such as iron and by light. Hydrogen sulfide also can combine with metals such as iron (Fe++) to precipitate as black iron sulfide (Figure 1 bottom; FeS and FeS2).
The following is multiple choice question (with options) to answer.
When iron and sulfur are mixed together in a certain ratio and heated, what do they become? | [
"iron sulfide",
"iron oxide",
"sulfuric acid",
"rust"
] | A | When iron and sulfur are mixed together in a certain ratio and heated, a chemical reaction occurs. This results in the formation of a unique new compound, called iron sulfide (FeS). A magnet cannot be used to mechanically separate the iron from the iron sulfide because metallic iron does not exist in the compound. Instead, another chemical reaction is required to separate the iron and sulfur. |
SciQ | SciQ-4657 | microbiology, population-biology
Title: How many eukaryotes are there on Earth? I have been reading:
William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF]
wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.
I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above? Could not fit in a comment....
To make sure we all understand your question...
Is your question how many (eukaryote) species are currently living? or How many (eukaryote) cells are currently living??
Just a hint to answer the question
Micheal Lynch, in his book (On the Origin of Genome Architecture) at page 3, Box 1.1 tries to answer the question How much DNA is there on earth?. He ends up with an estimation of a total length of DNA on earth of $10^{24}$ km for procaryotes, $10^{25}$ km for eukaryote (of which $\frac{1}{1000}$% is accounted to humans). This sums up to a total DNA length of $10^{12}$ light-years, or 10 times the diameter of the known universe!
In his calculations, he estimates that the total number of procaryote cells at $10^{30}$ (citing Whitman et al. 1998 as you did). He estimates the total number of eukaryote species to $10^7$, i.e. 6 times the number of known eukaryote species. However, he doesn't directly give any reference for this estimate but he refers to different chapters in the book that contain lots of references.
...I hope that helps...
The following is multiple choice question (with options) to answer.
What do many scientists think are the oldest eukaryotes? | [
"protists",
"plants",
"prokaryotes",
"arthropods"
] | A | Scientists think that protists are the oldest eukaryotes. If so, they must have evolved from prokaryotic cells. How did this happen? The endosymbiotic theory provides the most widely-accepted explanation. That’s because it is well supported by evidence. |
SciQ | SciQ-4658 | immunology, virology
Title: Why do people dying of immune deficiency diseases appear sick? Please forgive the obviously silly appearance of this question, and/or of the tenor which may come across as flippant or dismissive of real world suffering. My intention is none of the above.
As a layperson, I have always understood that the expression of our various colds/flus etc, while frequently mis-understood as being caused by the virus, are actually just manifestations of our own immunity fighting same. In other words, all the snot, and fever and inflammation are not caused *by the virus, they are a reaction *to the virus, as we fight it off.
My question then is why do people with AIDS (or similar immunity destroying affliction) appear sick? If they have weak or non-existent immune systems, following the above logic, would one expect to see them passing away while looking entirely healthy? Many of the symptoms of disease are indeed related to inflammation, but inflammation depends heavily (though not solely) on the innate immune response. Patients with AIDS and some of the other immunodeficiencies lose their adaptive immune response, not their innate response. Therefore they are capable of mounting an inflammatory response that is not effective in clearing pathogens (because it doesn't have help from the adaptive immune system) but can still cause symptoms.
More importantly, many symptoms of disease are not caused by the inflammatory response, but are related to organ and tissue damage caused by the infection. A patient with pneumonia may have a reduced inflammatory response but will still have difficulty breathing and signs of reduced oxygen supply simply because the lung tissue has been damaged by the pathogen.
The following is multiple choice question (with options) to answer.
Culprits in the common cold and aids, what infectious agents are far smaller and simpler than bacteria? | [
"pathogens",
"viruses",
"poisons",
"parasites"
] | B | Infectious diseases caused by viruses include the common cold, influenza, and acquired immunodeficiency syndrome (AIDS) and are among the most significant health problems in our society. Viruses are infectious agents far smaller and simpler than bacteria that are composed of a tightly packed central core of nucleic acids enclosed in a protective shell. The shell consists of layers of one or more proteins and may also have lipid or carbohydrate molecules on the surface. Because of their simplicity, viruses must invade the cells of other organisms to be able to reproduce. Viruses are visible only under an electron microscope. They come in a variety of shapes, ranging from spherical to rod shaped. The fact that they contain either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)—but never both—allows them to be divided into two major classes: DNA viruses and RNA viruses (Figure 19.17 "Viruses"). Figure 19.17 Viruses. |
SciQ | SciQ-4659 | rocks, remote-sensing, archaeology, ground-truth
Together, #1, #2, and #3 tell us that it's probably early summer just after the river ice has broken up.
The tooth-like features in the left image are simply erosional remnants sticking out of the riverbank. They could be bedrock (not likely), ice wedges, unmelted permafrost, or simply dirt. They are on the outside of a meander, so the river is actively cutting into them, and so the river-facing faces are quite sheer and high compared to the slopes in between. The right side might be white because the conditions there had left the snow unmelted when the image was taken. And of course their shadows are longer because the river channel is at the bottom of the bluff.
If you use Google Maps or Earth to go downriver a bit (up and to the left), you will see similar features sticking out of the riverbank, but because they're at a different angle from the features in your image, the fact that they're natural is more readily apparent.
Although the terrain is much less regular on the right side of the image, again the long shadows tell the tale. There are some round lumps that may be pingoes. The shadow that looks like a man is just a coincidental jumble of shadows from the broken terrain. If you look closely at the lump that is supposed to be the "man" (which would technically be an inunnguaq) does not have any protrusions that correspond to the "arms". The "arms" are the shadow of a little cliff or shelf past the lump, which is overlapped by the lump's larger shadow.
It's similar in effect to the infamous misinterpretation of a Viking orbiter image of a natural feature on Mars as a "Face on Mars".
This is a good example of the complications of image interpretation, specifically, understanding the conditions under which the image was taken. It's also a good time to emphasize the importance of doing ground truth when interpreting images. So when you go there, let us know what you find.
The following is multiple choice question (with options) to answer.
What triangular feature is formed when a river empties into a large body of still water? | [
"delta",
"flow",
"region",
"confluence"
] | A | Deposition also occurs when a stream or river empties into a large body of still water. In this case, a delta forms. A delta is shaped like a triangle. It spreads out into the body of water. An example is shown in Figure above . |
SciQ | SciQ-4660 | dna, human-genetics, dna-sequencing, genomics
Title: Is it possible to deduce facts about a person's parents just by studying his/her genome? As an example, suppose Anne had abusive parents. Is it theoretically possible to deduce this from her genome even if she didn't inherit this quality (of being an abusive parent)? It might seem pernickety but you often can't deduce from a genome; you can only infer from it. For many characteristics about a person, there are only rough, probabilistic associations between genotype and phenotype. Not one-to-one relationships.
You can take an educated guess that someone with a certain genotype could be a social person of European ethnicity with a low risk of psychosis, which might suggest things about their parents. But there are likely many genes that influence those characteristics and still more non-genetic factors. So you couldn't be certain.
For a factor like whether the persons parents had abusive personalities, I think the genetic differences would be so subtle (if existent) and there would be so many other factors (such as the habits and choices of the parents) that you would be very unlikely to be able to draw any conclusive associations. Articles and studies about linking human genetics with a person's characteristics are listed below. If any of the genes in question are linked with those characteristics then the parents of someone with the gene could possibly have those genes and characteristics too.
Personality types including belligerence, charisma, cynicism, housekeeping, lack of personality, obsessive-compulsive behaviour and gullibility.
Psychosis and Schizophrenia risks.
Ethnicity and European ethnicity, which in turn correlate with geographical location, language and certain phenotypes.
Height.
If anyone would like to suggest additions to that list, I'll happily add them.
The following is multiple choice question (with options) to answer.
Professionals known as genetic counselors can help them understand the risks of? | [
"contagion",
"infection",
"children being affected",
"disease"
] | C | A genetic disorder that is caused by a mutation can be inherited. Therefore, people with a genetic disorder in their family may be concerned about having children with the disorder. Professionals known as genetic counselors can help them understand the risks of their children being affected. If they decide to have children, they may be advised to have prenatal (“before birth”) testing to see if the fetus has any genetic abnormalities. One method of prenatal testing is amniocentesis. In this procedure, a few fetal cells are extracted from the fluid surrounding the fetus, and the fetal chromosomes are examined. |
SciQ | SciQ-4661 | climate-change, climate
In this case, as it is an area that it is almost constantly cloudy with high humidity, temperature is varying just a little bit, and except the first day of the period, it seems that there is no relationship. In fact, on the second day there was a storm (I am living now at Singapore) and it is reflected in a quick change in temperature (both) and solar radiation.
Conclusion: It is not as simple as it seems.
Hope it helps!
The following is multiple choice question (with options) to answer.
What type of fronts often bring sudden changes in the weather, including different types of precipitation, depending on the season? | [
"warm fronts",
"stationary fronts",
"occluded fronts",
"cold fronts"
] | D | As the fast-moving cold air mass keeps advancing, so does the cold front. Cold fronts often bring sudden changes in the weather. There may be a thin line of storms right at the front that moves as it moves. In the spring and summer, the storms may be thunderstorms and tornadoes. In the late fall and winter, the storms may bring snow. After a cold front passes, the cold air mass behind it brings cooler temperatures. The air is likely to be less humid as well. Can you explain why?. |
SciQ | SciQ-4662 | 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.
Similarity in biochemicals, like the glucose used by virtually all living things for energy, provides evidence of what? | [
"gravity",
"variation",
"DNA",
"evolution"
] | D | Virtually all living things use glucose for energy, but glucose is just one of many examples of biochemical compounds that are found in most or all living things. In fact the similarity in biochemical compounds between living things provides some of the best evidence for the evolution of species from common ancestors. A classic example is the biochemical compound called cytochrome c. It is found in all living organisms because it performs essential life functions. Only slight variations in the molecule exist between closely related species, as you can see in the Figure below . The molecule is identical in humans and their closest relatives, the chimpanzees. And even between humans and the single-celled tetrahymena (pictured in the Figure below ), the cytochrome c molecule is nearly 50 percent the same. |
SciQ | SciQ-4663 | cell-culture
Title: Which human cell lines do not express the GLP-1 receptor? I need a human cell line that does not express the GLP-1 (glucagon like peptide-1) receptor.
I'm working with HeLa cells, do those express the GLP-1 receptor? Which other cell lines exist that don't express this specific receptor?
Are there any general resources where I could find this kind of information? AbCam suggests HeLa cells as positive controls for their antibody to GLP1R. They provide the following pictures of HeLa cells labeled with their antibody:
(The image of the right is treated with synthesized peptide.)
According to Wikipedia, GLP1R is also expressed in pancreatic beta cells and the brain.
The following is multiple choice question (with options) to answer.
In type 2 diabetes, body cells do not respond to normal amounts of what hormone? | [
"estrogen",
"insulin",
"hemoglobin",
"glucose"
] | B | In some cases, an endocrine gland secretes a normal amount of hormone, but target cells do not respond to the hormone. Often, this is because target cells have because resistant to the hormone. Type 2 diabetes is an example of this type of endocrine disorder. In Type 2 diabetes, body cells do not respond to normal amounts of insulin. As a result, cells do not take up glucose and the amount of glucose in the blood becomes too high. This type of diabetes is not generally treated with insulin injections. Instead, it is usually treated with medication and diet. |
SciQ | SciQ-4664 | neuroscience, physiology, human-physiology, reflexes
Title: Are there neuron mediated reactions faster than reflexes? I'm interested in how fast the human body can respond to a stimulus. I know the fastest reflex, the blink reflex, operates around 100ms from stimulus to reaction. I also know that the blink reflex is known as the fastest reflex in the human body. My interest is in the fastest responses to stimuli I can find in the body.
Are there any faster responses to stimuli within the human body which use neurons but are not categorized as a reflex (due to some technicality), meaning they could be faster than the fastest reflex? To the best of my understanding a reflex is defined by the use of neurons to convey the information, I'm just wondering if there are any grey areas which don't qualify as a reflex but may be faster. I don't want to potentially write off an entire class of neurological behavior in my research simply because I stopped at the blink reflex. A reflex as fast as the blink in a neural circuit:
I would consider suppression of outer hair cells in the cochlea to be a reflex; the faster component of this reflex is about the same as the blink reflex, around 100 ms. The hair cells themselves aren't considered neurons, but the pathway that suppresses their motility certainly is.
A much much faster non-neuronal "reflex":
That said, the outer hair cells themselves also dance along quite fast in response to sensory input, even faster than the typical hearing range for humans, faster than 20kHz! In some ways, this is a reflex because you are taking sensory (specifically, auditory) information and turning it into a motor response, but all the "action" is taking place within one cell, and it isn't a neuron.
A more classical reflex that is substantially faster than 100 ms
Reflexes in the periphery can be much faster than 100 ms. The myotatic reflex, or stretch reflex, can be as fast as 30 ms in the knee - this is the reflex that is tested when a physician smacks you on the knee with a hammer (used as a test of spinal and peripheral nerve function, not as a punishment). It's likely there are other stretch reflexes that are faster just because distances to the spinal cord are shorter, but these might be more difficult to test (in this paper they report latencies as fast as 20 ms).
The following is multiple choice question (with options) to answer.
What fibres are seen in some vertebrates that twitch at rates far faster than any human muscle? | [
"skeletal muscle fibers",
"fast oxidative fibres",
"slow twitch fibres",
"fast glycolytic fibres"
] | A | |
SciQ | SciQ-4665 | cell-biology, development, embryology
Title: What is cytoplasmic localization? I was studying development of chick but didn't understand what is cytoplasmic localization. My book says:
After third cleavage , the rest of the cleavages are irregular and completely delimited cells are formed all over the germinal disc which is termed as blastoderm. This outcome of cleavage called cytoplasmic localization helps seal the developmental fate of each cell's descendants. "Cytoplasmic localization" is a very general term and it means that something is present in the cytoplasm. For instance (hypothetical but there are known examples), you can say protein-X is localized to cytoplasm or the cytoplasmic localization of protein-Y is reduced upon phosphorylation. Similarly, there are terms like "nuclear localization", "ER localization", "mitochondrial localization" etc.
The usage mentioned in your excerpt is actually unclear and misleading. There is no process called cytoplasmic localization. What it actually means is that there are proteins/RNA inside the cytoplasm of the embryo that are asymmetrically distributed. When the cell divides, these molecules are therefore asymmetrically sorted to the daughter cells. Depending on what (and how much of) molecules the daughter cells receive, different cells adopt different phenotypes. Also note that the axis of division also plays a role; if lets say the distribution of a given molecule is asymmetric only about the anteroposterior axis and the division happens along that axis then both daughter cells receive the same amount of molecule and both the cells would be similar (w.r.t that molecule). This won't be the case if the division is along left-right axis. See the figure below.
From: Berika et al., 2014
I am not sure which book you are following but Developmental Biology by Scott F Gilbert is a good book and explains these processes nicely.
The following is multiple choice question (with options) to answer.
The cytoplasm divides during what process? | [
"cytokinesis",
"genesys",
"metamorphosis",
"osmosis"
] | A | During mitosis , the nucleus divides as the chromosomes are equally separated. One nucleus becomes two nuclei, each with an identical set of chromosomes . Mitosis is followed by cytokinesis , when the cytoplasm divides, resulting in two cells. After cytokinesis, cell division is complete. The one parent cell (the dividing cell) forms two genetically identical daughter cells (the cells that divide from the parent cell). The term "genetically identical" means that each cell has an identical set of DNA, and this DNA is also identical to that of the parent cell. If the cell cycle is not carefully controlled, it can cause a disease called cancer in which the cells divide out of control. A tumor can result from this kind of growth. |
SciQ | SciQ-4666 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
Where do birds store and moisten food that is waiting to be digested? | [
"nest",
"crop",
"gullet",
"tree"
] | B | Birds have a sac-like structure called a crop to store and moisten food that is waiting to be digested. They also have an organ called a gizzard that contains swallowed stones. The stones make up for the lack of teeth by grinding food, which can then be digested more quickly. Both structures make it easier for the digestive system to produce a steady supply of nutrients from food. |
SciQ | SciQ-4667 | meteorology, geomorphology, climatology, atmospheric-circulation
Source Commons Wikipedia.
The cold waters near the ocean surface results in a cool, stable coastal atmosphere. In this region, evaporation from the ocean is reduced and produces extremely low rainfall over land. Precipitation is limited to morning fog and produces some of the driest ecosystems on Earth. The Atacama desert is the best example of such environment with average rainfalls of 15 mm/year (the driest non-polar region). In some areas, they are trying to take advantage of the little moisture the fog (Camanchaca) brings to establish some agricultural zones. The fog droplets are too small (1-40 micrometers) to form water drops and precipitate, so they use fog-catchers to collect moisture from the fog.
Source: newatlas.com
The following is multiple choice question (with options) to answer.
Where can you find humid subtropical climates? | [
"between 40 and 60 degrees latitude",
"between 40 and 60 degrees longitude",
"between 20 and 40 degrees latitude",
"between 20 and 40 degrees longitude"
] | C | Humid subtropical climates are found on the eastern sides of continents between about 20° and 40° latitude. The southeastern U. S. has this type of climate. Summers are hot and humid, but winters are chilly. There is moderate rainfall throughout the year. Pine and oak forests grow in this climate ( Figure below ). |
SciQ | SciQ-4668 | optics, refraction, lenses, vision
Title: Refractive screen for myopia Is it possible to create a screen for a computer monitor to allow a Myopic person to see the screen without glasses? Myopia shortens the maximum focus length of an eye, i.e., the converging action of a myopic eye is too strong and, as a result, the image of a distant object is formed in front of the retina - not on the retina.
Nearsighted vision is corrected by placing a corrective concave lens in front of the eye - its diverging action compensating the excessive converging action of the eye. We can also say that, by its diverging action, the concave lens brings distant objects closer to the eye - to some short distance from which a myopic eye can focus them properly.
The stronger the myopia, the stronger the required concave lens action, the shorter that "clear vision" distance.
For this paradigm to work, the corrective lens has to be located closer to the eye than the clear vision distance and a distant object, which requires correction, has to be located further from the eye than the clear vision distance.
Obviously, under these conditions, the monitor and its corrective lens would have to be separated in space, which means that the corrective lens cannot be built into the screen.
Of course, we could have a giant magnifying glass built into the screen, like it was done in early TV's with tiny screens. This would magnify the image and make it easier to make out the details, but the image would still be out of focus.
The following is multiple choice question (with options) to answer.
What type of lenses can correct myopia? | [
"diffusion lenses",
"polarized lenses",
"convex lenses",
"concave lenses"
] | D | Nearsightedness, or myopia, is the condition in which nearby objects are seen clearly, but distant objects appear blurry. The eyeball is longer than normal, focusing images front of the retina. Concave lenses can correct the problem. |
SciQ | SciQ-4669 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
Photoautotrophs including (a) plants, (b) algae, and (c) cyanobacteria synthesize their organic compounds via photosynthesis using sunlight as this? | [
"fuel source",
"light source4",
"heating source",
"energy source"
] | D | Figure 8.2 Photoautotrophs including (a) plants, (b) algae, and (c) cyanobacteria synthesize their organic compounds via photosynthesis using sunlight as an energy source. Cyanobacteria and planktonic algae can grow over enormous areas in water, at times completely covering the surface. In a (d) deep sea vent, chemoautotrophs, such as these (e) thermophilic bacteria, capture energy from inorganic compounds to produce organic compounds. The ecosystem surrounding the vents has a diverse array of animals, such as tubeworms, crustaceans, and octopi that derive energy from the bacteria. (credit a: modification of work by Steve Hillebrand, U. Fish and Wildlife Service; credit b: modification of work by "eutrophication&hypoxia"/Flickr; credit c: modification of work by NASA; credit d: University of Washington, NOAA; credit e: modification of work by Mark Amend, West Coast and Polar Regions Undersea Research Center, UAF, NOAA). |
SciQ | SciQ-4670 | glaciology, ice-sheets, glaciation
It should be added the the understanding of the variations of the last ice sheet come from a series of indirect sources such as sea-level changes, paleo-climate records e.g., (ice cores) and interstadial paleoclimate reconstructions. This means that as our understanding of these indirect records are improved, we can also improve our ice sheet forcing. Add to that uncertainties about basal conditions beneath past ice sheets that affect their dynamics and it is easy to see that past ice thickness values are uncertain. We can, however, obtain reasonable estimates from the models which could be accurate to within, perhaps 500 m (my guestimate).
The following is multiple choice question (with options) to answer.
Glaciers modify the landscape by what? | [
"erosion",
"sediment",
"silt",
"truncation"
] | A | Glaciers modify the landscape by erosion. They also modify the landscape by deposition. Glaciers carry an enormous amount of material and dump it. The features they leave behind show where they were and what happened as they were melting away. |
SciQ | SciQ-4671 | reproduction
Excerpts from the references that lead to the short answer above:
In the developing female fetus, oogonia become primary oocytes that begin the first division of meiosis. However, this division is not completed and the primary oocytes remain “frozen” in the prophase stage of the first meiotic division.
At birth, oogonia are no longer present. Each primary oocyte is surrounded by a single layer of squamous epithelial cells called follicular cells. The primary oocyte together with its follicular cells is called a primordial follicle. There are about two million primordial follicles with their primary oocytes in the ovaries at birth suspended in the first division of meiosis.
As the female grows, primary oocytes begin to die and disappear with their follicular cells. This process continues until puberty when there are only about 400,000 primordial follicles left in the ovaries. The primary oocytes continue the process of oogenesis after puberty begins.[Source]
The total number of primary oocytes at birth is estimated to vary from 700,000 to2 million. During childhood most oocytes become atretic; only approximately400,000 are present by the beginning of puberty, and fewer than 500 will be ovulated.[Source]
Primary oocytes reach their maximum development at ~20[6] weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million.Recently, however, two publications have challenged the belief that a finite number of oocytes are set around the time of birth.[Source]
In the human embryo, the thousand or so oogonia divide rapidly from the second to the seventh month of gestation to form roughly 7 million germ cells.[Source]
REFERENCES:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008772
The following is multiple choice question (with options) to answer.
The cells in the follicle undergo physical changes and produce a structure called a what? | [
"primordial follicle",
"secondary ovum",
"corpus luteum",
"liberated ovum"
] | C | Following ovulation, the ovarian cycle enters its luteal phase, illustrated in Figure 43.15 and the menstrual cycle enters its secretory phase, both of which run from about day 15 to 28. The luteal and secretory phases refer to changes in the ruptured follicle. The cells in the follicle undergo physical changes and produce a structure called a corpus luteum. The corpus luteum produces estrogen and progesterone. The progesterone facilitates the regrowth of the uterine lining and inhibits the release of further FSH and LH. The uterus is being prepared to accept a fertilized egg, should it occur during this cycle. The inhibition of FSH and LH prevents any further eggs and follicles from developing, while the progesterone is elevated. The level of estrogen produced by the corpus luteum increases to a steady level for the next few days. If no fertilized egg is implanted into the uterus, the corpus luteum degenerates and the levels of estrogen and progesterone decrease. The endometrium begins to degenerate as the progesterone levels drop, initiating the next menstrual cycle. The decrease in progesterone also allows the hypothalamus to send GnRH to the anterior pituitary, releasing FSH and LH and starting the cycles again. Figure 43.17 visually compares the ovarian and uterine cycles as well as the commensurate hormone levels. |
SciQ | SciQ-4672 | earthquakes, seismology, instrumentation, in-situ-measurements, diy
Title: Using accelerometer as a seismograph I'm using ADXL345 accelerometer with Raspberry Pi to build a seismograph. I've successfully hooked it up and can plot the accelerometer data in three axis. Is there any way to express these data in the form of the magnitude of an earthquake, of course, at the point of sensing? I know that it might be imprecise, but any representation would be helpful (e.g. Richter scale), and how to accomplish that. The magnitude of an earthquake is related to the total energy released, therefore to estimate it from a seismogram you need to know the distance to the source. In the case of the Richter scale for example, the relationship between magnitude and seismogram amplitude is defined for a standard distance.
If you have only one seismograph, you can not triangulate the location of the source (hypocenter). Therefore, you can not estimate the magnitude of a seismic event (Richter or moment magnitude).
But you can estimate the local seismic intensity of the event at the particular location of your instrument. With the accelerometer data you can easily measure the peak ground acceleration, that can be used to estimate the intensity in any of the existing scales. For example, the peak ground accelerations associated to each intensity level in the commonly used Mercalli intensity scale are:
Those g values would be easy to calculate with the accelerometer data and proper calibration constants.
Table taken from the Wikipedia page for peak ground acceleration
You might want to have a look at this question. There are some nice answers and references that you might find useful.
The following is multiple choice question (with options) to answer.
Scientists can use what tool to determine an earthquake's strength? | [
"telescope",
"kilocalorie",
"seismogram",
"geiger counter"
] | C | Seismograms record earthquake strength. Scientists can use them to determine the distance to an earthquake. Using at least three seismograms, they can locate the earthquake's epicenter. Scientists measure earthquake intensity in several ways. So far no one has found a way to predict earthquakes. |
SciQ | SciQ-4673 | jupiter, natural-satellites
Title: Why does Jupiter have so many moons? Jupiter has a great many moons - in the hundreds, and they're still being discovered.
What is the current theory for where all these moons came from? Are they rocks flying through space captured by Jupiter's gravity? Mass.
The more massive a body, the larger the gap between its lowest and highest orbit; the range of speeds at which a random body entering its gravity is likely to remain as its satellite. Sun has millions of satellites if you count all the asteroids; smaller planets tend to have one or two moons at most (Pluto with five being a notable and not fully explained exception)
To a lesser degree there's a matter of shape too. A regularly round body will have more regular and stable orbit than a potato-shaped one. Jupiter, being a gas giant is perfectly round. This doesn't play that much of a role though, especially with higher orbits.
And last but not least, no destabilizing influence of other bodies. It's very hard to maintain a lunar orbit - artificial satellites around our Moon last only a couple years each, because relatively close neighborhood of Earth tends to destabilize orbit of anything orbiting the Moon. Jupiter being a single massive planet with relatively tiny (relatively to its mass) moons doesn't have them influence each other all that much.
The following is multiple choice question (with options) to answer.
How many moons does pluto have? | [
"six",
"two",
"four",
"three"
] | D | Pluto has three moons of its own. The largest, Charon, is big compared to Pluto. The Pluto-Charon system is sometimes called a double dwarf planet ( Figure above ). Two smaller moons, Nix and Hydra, were discovered in 2005. |
SciQ | SciQ-4674 | geophysics, hydrology, geysers
Are the 65 minute and 91 minute values given for the eruption times simply a byproduct of needing more time for the steam to "recharge" after a larger eruption, or is there a deeper interplay between the underground cavity and the main channel that causes some sort of a vortex that has a (somewhat) regular periodicity? First I would like to say this is not my area of expertise, so this should perhaps be a comment but I am not allowed yet to comment on this site.
In a simplistic view a geyser has heated water chamber with a column of water above it. The water is heated above the normal boiling temperature but is kept liquid by the pressure of the water column above it. When the water eventually starts to vaporize this reduces the pressure on the water in the chamber resulting in more rapid vaporization of the water in the chamber resulting in the eruption.
For Old Faithful assume two chambers, one chamber is lower than the other. If the temperatures in both chambers are high enough the vaporization in the upper chamber would also reduce the pressure in the lower chamber allowing it to vaporize resulting in both chambers emptying, resulting in a longer eruption. Assuming the infill and heating rates are essentially constant then the time before the next eruption would take longer because both chambers are "empty". On the other hand if the upper chamber vaporizes and but the lower one does not, either because it is not hot enough or the pressure hasn't dropped enough or back pressure from the upper chamber keeps the lower chamber liquid, then only the upper chamber will empty resulting in less time to infill and reheat.
Again not my area.
The following is multiple choice question (with options) to answer.
Huge calderas form when the mountain above an empty chamber of what collapses? | [
"magma",
"gas",
"coal",
"mercury"
] | A | During a massive eruption, all of the material may be ejected from a magma changer. Without support, the mountain above the empty chamber may collapse. This produces a huge caldera . Calderas are generally round, bowl-shaped formations ( Figure below ). |
SciQ | SciQ-4675 | atomic-physics
Title: What gives covalent bond its strength? I came across the following passage from Structure and Properties chapter of Morrison-Boyd Organic Chemistry:
What gives the covalent bond its strength? It is the increase in electrostatic attraction. In the isolated atoms, each electron is attracted by-and attracts-one positive nucleus;in the molecule, each electron is attracted by two positive nuclei.
However, I don't think it refers to the force holding each atom together. It rather, merely describes the increase in the electrostatic force of attraction between the electrons and the nuclei. I believe that bond strength is a measure of the difficulty in pulling apart the component atoms, not the electrons from the positive nuclei.
What exactly is the pattern or picture of the forces on the nuclei and the electrons, due to one another, that holds the component atoms together? (I am aware that the decrease in overall energy or increase in stability is definitely not a reason to account for the strength of covalent bond, but rather a consequence of the action of such forces.) It probably helps to define what a covalent bond really is. Covalent bonds occur when one or more Atomic Orbitals (AO) of the participating atoms constructively interact and form a (bonding) Molecular Orbital (MO). The figure below schematises the formation of a $\sigma_{ss}$ MO when two hydrogen atoms combine to form a dihydrogen molecule:
The following is multiple choice question (with options) to answer.
What type of bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms? | [
"covalent",
"reactive",
"gravitational",
"active"
] | A | Note that there is a system for naming some polyatomic ions; -ate and -ite are suffixes designating polyatomic ions containing more or fewer oxygen atoms. Per- (short for “hyper”) and hypo- (meaning “under”) are prefixes meaning more oxygen atoms than -ate and fewer oxygen atoms than -ite, respectively. For example, perchlorate is ClO 4 − , chlorate is ClO 3 − , chlorite is ClO 2 − and hypochlorite is ClO−. Unfortunately, the number of oxygen atoms corresponding to a given suffix or prefix is not consistent; for example, nitrate is NO 3 − while sulfate is SO 4 2−. This will be covered in more detail in the next module on nomenclature. The nature of the attractive forces that hold atoms or ions together within a compound is the basis for classifying chemical bonding. When electrons are transferred and ions form, ionic bonds result. Ionic bonds are electrostatic forces of attraction, that is, the attractive forces experienced between objects of opposite electrical charge (in this case, cations and anions). When electrons are “shared” and molecules form, covalent bonds result. Covalent bonds are the attractive forces between the positively charged nuclei of the bonded atoms and one or more pairs of electrons that are located between the atoms. Compounds are classified as ionic or molecular (covalent) on the basis of the bonds present in them. |
SciQ | SciQ-4676 | atoms
Title: Conversion atom to another One child has claimed to have find a solution to all physical problems. On asking for details, he said that all periodic elements has common components, i.e. electrons, protons, neutrons.
The child has suggested a solution: convert atom to another by adding electron. This way one can get substance like $\ce{H2O, Au, He}$ in abundance.
How can it be done? While what you suggest may sound nice on paper, it has some serious problems.
Getting the elements. Let's say that we're talking about purifying water to remove toxic elements such as Hg or Cd. Extracting the elements out of the water is a feat by itself, for example using reverse osmosis methods. This is a method used for seawater desalination - to turn them from salt water filled with all kinds of elements into drinkable water. This process is very expensive, and a very polluting one as well. Desalination just the amount of water you need for drinking water is complicated, so desalinating an entire reservoir is simply not going to happen.
Let's say you did somehow manage to extract the element in question. Now you need nuclear reactions to transmute one element to another. Not all are possible. For some elements, like Tc or Am this is the only way you can produce them. However, you are going to end up with radioactive nuclear waste.
To sum it up, even if it was possible, you would need so much power and to do it and you will produce some much pollution that it's simply not worth it. Just going and mining the gold will be orders of magnitude cheaper (and probably cleaner) than producing it using nuclear reactions.
If you do manage to somehow extract the the polluting elements, you usually do something else with them (aka recycling) and you do not attempt being an alchemist. Another example is soils contaminated with lead. The solution is to just dig it up, put it somewhere where it is not hazardous to anyone and replace it with clean soil.
The following is multiple choice question (with options) to answer.
Chemical elements and water are constantly recycled in the ecosystem through what? | [
"greenhouse gases",
"geothermal cycles",
"inorganic cycles",
"biogeochemical cycles"
] | D | Chemical elements and water are constantly recycled in the ecosystem through biogeochemical cycles. |
SciQ | SciQ-4677 | neuroscience, neuroanatomy
Likewise, the spinal chord is structured into sensory and motor regions. In summary, the spinal chord consists of: 1) cell bodies (motor, sensory, inter; grey in the picture), 2) ascending axons (blue), 3) descending axons (red). Similar to nerves, axons going up or down the spinal chord are bundled into "tracts". Sensory axons are never bundled with motor axons, making it possible to create a map of the spinal chord in cross-section.
The tracts' names might be a bit confusing at first, but on second look are actually pretty self-explanatory. They usually contain where the axons come from and where they are going in order to synapse with other neurons. E.g. the spinocerebellar tract is formed of axons coming from the spine and going to the cerebellum. Given that the cerebellum is near the brain and the spine is further down, this is obviously an ascending tract - and ascending tracts are always sensory (because sensory information never needs to be carried downwards due to the brain being at the top).
Where it gets blurry
The sensory/motor separation isn't always as clear as I've described above. In fact, nerves (bundles of axons anywhere in the body outside of the CNS) will usually contain both sensory and motor pipelines. In particular, the cranial nerves (12 of the most important nerves) all include sensory and motor components for the respective part of the body that they manage. E.g. the facial nerve contains both the sensory connections for parts of the tongue and the motor connections that control facial muscles.
Another more complex example is pain sensation, where interneurons in the spinal chord can feed back onto sensory neurons and inhibit their signals, or axons can inhibit those packed in the same nerve bundle simply due to electrical effects.
The following is multiple choice question (with options) to answer.
What system is the spinal cord related to? | [
"digestive system",
"lymphatic system",
"circulatory system",
"nervous system"
] | D | Some people recover from spinal cord injuries. But many people are paralyzed for life. Thanks to the work of Christopher Reeve ( Figure below ), more research is being done on spinal cord injuries now than ever before. For example, scientists are trying to discover ways to regrow damaged spinal cord neurons. |
SciQ | SciQ-4678 | homework-and-exercises, radiation, earth, sun
Title: How much radiation does the Earth receive from the Sun's total radiation? I was thinking how to solve this problem. $1\,\mathrm{AU}$ is roughly the distance from the Earth to the Sun, $1.4960 \times 10^{11}\,\mathrm{m}$.
The radius of Earth is approximately $6.4 \times 10^{6}\,\mathrm{m}$, and the radius of the Sun is approximately $6.96 \times 10^{8}\,\mathrm{m}$.
How could we estimate the percent of radiation which the Earth receives, ignoring astrophysical "noise" like dust?
The radiation emitted by the Sun roughly follows the Stefan-Boltzmann law and the radiation emitted is roughly $\propto T^4$, and the surface area of the Earth is roughly $\propto r^2$.
Would you simply take the ratio between the Sun's surface area divided by the Earth's surface area?
All the Sun's power $P$ passes uniformly through a sphere with radius of 1 AU. Calculate the total surface area of this sphere and call it $S$.
The Earth's disc also has a surface area that can be calculated from its radius. Call this surface $S_E=\pi R_E^2$.
The fraction of the Sun's power received by the Earth is thus:
$f=P\frac{S_E}{S}$.
The following is multiple choice question (with options) to answer.
What is the total range of the energy from the sun called? | [
"solar spectrum",
"electromagnetic spectrum",
"measured spectrum",
"molecular spectrum"
] | B | Energy from the Sun has a wide range of wavelengths. The total range of energy is called the electromagnetic spectrum ( Figure below ). |
SciQ | SciQ-4679 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
Plants have specialized organs that help them survive and reproduce in a great diversity of habitats. major organs of most plants include roots, stems, and what? | [
"leaves",
"clusters",
"lungs",
"sacs"
] | A | Plants have specialized organs that help them survive and reproduce in a great diversity of habitats. Major organs of most plants include roots, stems, and leaves. |
SciQ | SciQ-4680 | evolution, anatomy, organs
Title: Why Is Most Life Symmetrical Externally But Not Internally? Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance.
Take a human for instance, make a line from the top of our head right down the middle. However, internally it is not the same. Our organs excluding the kidneys, lungs, reproductive organs, etc are not symmetrically placed in our body.
The following is multiple choice question (with options) to answer.
The lungs of mammals are unique in having what? | [
"glands",
"acini",
"alveolar",
"alveoli"
] | D | The lungs of mammals are unique in having alveoli . These are tiny, sac-like structures. Each alveolus is surrounded by a network of very small blood vessels (see Figure below ). Because there are millions of alveoli in each lung, they greatly increase the surface area for gas exchange between the lungs and bloodstream. Human lungs, for example, contain about 300 million alveoli. They give the lungs a total surface area for gas exchange of up to 90 square meters (968 square feet). That’s about as much surface area as one side of a volleyball court!. |
SciQ | SciQ-4681 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
The organs of female mammals that that produce eggs are called what? | [
"fallopian tubes",
"ovaries",
"testes",
"Uterus"
] | B | Like other female vertebrates, all female mammals have ovaries. These are the organs that produce eggs (see Figure below ). Therian mammals also have two additional female reproductive structures that are not found in other vertebrates. They are the uterus and vagina. |
SciQ | SciQ-4682 | amateur-observing, supernova
It is a star cluster in the constellation of Taurus which is inspired from a popular Greek mythology of Seven Sisters. You can read more about it here.
EDIT: One of the great softwares, free and open source, for amateur level observational astronomy, though professionals use it as frequently is Stellarium. It's easy to use and should clear all your doubts.
The following is multiple choice question (with options) to answer.
What do you call the patterns and groups of stars in the sky that ancient people observed and made stories about? | [
"constellations",
"asteroid fields",
"planets",
"meteors"
] | A | The stars that make up a constellation appear close to each other from Earth. In reality, they may be very distant from one another. Constellations were important to people, like the Ancient Greeks. People who spent a lot of time outdoors at night, like shepherds, named the constellations. They told stories about them. Pictured below is one of the most easily recognized constellations ( Figure below ). The ancient Greeks thought this group of stars looked like a hunter. They named it Orion, after a great hunter in Greek mythology. |
SciQ | SciQ-4683 | equilibrium, enzyme-kinetics
[OP] I based the kinetics for these reactions on Michaelis-Menten kinetics, so every enzyme has a $V_{max}$ and $K_M$, and has velocity $v=V_{max}x /(K_M+x)$
The product $P$ has a maximum rate of $r_\mathrm{P,max}$, not the enzyme. This value is obtained when the substrate is so abundant that $[S] \gg K_\mathrm{M}$.
[OP] I use the Reaction Quotient $Q$ at any point in time to determine in which direction a reaction would proceed. E.g. would (net/overall) $A$ be converted to $B$ or vice versa. Each reaction is defined with a reaction energy which is used to calculate Equilibrium constant $K_e$.
You have as many reaction quotients $Q$ as reversible chemical reactions. You can do this for $\text{R1}$ because this step is reversible. However, you cannot do this for $\text{R2}$, because for the M-M mechanism this step is irreversible. Thus, once any quantity of $\ce{ES}$ complex has been formed, $\text{R2}$ will proceed, independently if you had a lot of $\pu{P}$ at $t=0$.
My understanding is that Miachelis-Menten kinetics only describe the case in which $Q<<K_e$. What happens if $Q→K_e$?
A reaction quotient is not defined for irreversible reactions.
Intuitively I would assume that the overall reaction velocity slows down as $Q$ approaches $K_e$. Is there a term that I can add to the Michaelis-Menten equation which would describe this decreasing $v$?
The following is multiple choice question (with options) to answer.
Each enzyme has an optimal what at which its reaction rate is greatest? | [
"temperature",
"precipitation",
"weight",
"size"
] | A | |
SciQ | SciQ-4684 | life, extremophiles
Title: How close to Earth's core can organisms live? We don't to know much about organisms living deep below the Earth's crust. Recently a team led by S. Giovanni discovered some microbes 300 m below the ocean floor. The microbes were found to be a completley new and exotic species and apparently they feed off hydrocarbons like methane and benzene. Scientists speculate that life may exist in our Solar System far below the surface of some planets or moons. This raises some questions:
What is the theoretical minimum distance from Earth's core where life can still exist. Please explain how you came up with this number. For example, there are temperature-imposed limits on many biochemical processes.
Is there the potential to discover some truly alien life forms in the Earth's mantle (by this I mean, life which is not carbon based, or life which gets its energy in ways we have not seen before, or non DNA-based life, or something along these lines)?
What is the greatest distance below the Earth's crust that life has been discovered? I believe it is the 300 m I cited above, but I am not 100% sure. There's a lot we don't know about life in deep caves, but we can bound the deepest living organism to at least 3.5 kilometers down, and probably not more than 30 kilometers down.
The worms recovered from deep mining boreholes are not particularly specifically adapted to live that far down: they have similar oxygen/temperature requirements as surface nematodes.
The Tau Tona mine is about 3.5 kilometers deep and about 60˚ C at the bottom. Hydrothermal vent life does just fine up to about 80˚C, and the crust gets warmer at "about" 25˚C per kilometer. It's entirely reasonable to expect life to about 5 kilometers down, but further than that is speculation.
Increasing pressure helps to stabilize biological molecules that would otherwise disintegrate at those temperatures, so it's not impossible there could be life even deeper. It may even be likely, given that the Tau Tona life breathes oxygen.
I am certain no life we might recognize as life exists in the upper mantle.
The following is multiple choice question (with options) to answer.
What type of prokaryotes live in habitats without oxygen? | [
"phosphoric",
"anaerobic",
"aerobic",
"enzymatic"
] | B | Anaerobic prokaryotes live in habitats without oxygen. |
SciQ | SciQ-4685 | physical-chemistry, metals
Title: Why is quicksilver (mercury) liquid at room temperature? This is a nice question when you find it out, and I am really looking for a proper answer.
Take quicksilver (Hg) in the periodic table. It has one proton more than Gold (melting point 1337.33 K), and one less than Thallium (melting point 577 K). It belongs to the same group as Zinc (692.68 K) and Cadmium (594.22 K). All not very high melting points, but still dramatically higher than quicksilver (234.32 K). When his neighbors melt, quicksilver vaporizes (at 629.88 K).
What is the reason for this exceptional behavior of quicksilver ? Although the question has been partially answered, there is a superb reference on this topic which will certainly give you some of the deep, and not so deep insights needed to understand the answer to this question.
http://pubs.acs.org/doi/abs/10.1021/ed068p110
Nevertheless, both the contraction of the s(1/2) orbitals predicted by the Dirac equation, and the filled valence shell of Hg are the major causes for the odd physical properties of Hg. However, there are other effects that should be considered and the paper above is pretty clear on those.
Let me reformulate in order to make things clearer and more specific:
The reason for liquid Hg can be stated simply: the outer electrons of Hg (6s2) that participate in metallic bonds are "less available" to bonding (which might be observed for example by looking at binding energies of clusters of Hg, dimers, etc) then in other common metals, and hence the interaction between Hg atoms is much weaker compared to other metal-metal bonds. The explanation for the "less availability" of the 6s electrons is the contraction of the 6s orbitals, caused by the high speeds achieved by those electrons. This effect is promptly predicted by the Dirac equation.
The following is multiple choice question (with options) to answer.
What is the only metal that is liquid at room temperature? | [
"mercury",
"hydrogen",
"gas",
"water"
] | A | A familiar liquid is mercury metal. Mercury is an anomaly. It is the only metal we know of that is liquid at room temperature. Mercury also has an ability to stick to itself (surface tension) – a property all liquids exhibit. Mercury has a relatively high surface tension, which makes it very unique. Here you see mercury in its common liquid form. |
SciQ | SciQ-4686 | biochemistry, plant-physiology, plant-anatomy
Title: Why do plants store energy as carbohydrates and not as fats? In my introductory biology class, we are learning about biomolecules. The textbook says fats are a more efficient energy store than carbohydrates.
So my question is - why would plants store their energy as carbohydrates and not as fats, if fats are a more efficient energy store? There are quite some reasons for why plants prefer carbohydrates for energy storage rather than fats. I will reach some of them one at a time.
The following is multiple choice question (with options) to answer.
What do animals store with the help of saturated fatty acids? | [
"energy",
"protein",
"oxygen",
"sugar"
] | A | In saturated fatty acids , carbon atoms are bonded to as many hydrogen atoms as possible. This causes the molecules to form straight chains, as shown in Figure below . The straight chains can be packed together very tightly, allowing them to store energy in a compact form. This explains why saturated fatty acids are solids at room temperature. Animals use saturated fatty acids to store energy. |
SciQ | SciQ-4687 | the-moon, moon-phases
Title: Red cresent moon Yesterday night i witnessed something very strange when i looked outside the window. I saw the moon (crescent) but it was dull red and right on the horizon ,which is strange considering that it is usually on the upper right of the night sky and white in colour. On further inspection with my binoculars i noticed it was lowering down until it was hidden by the mountain range (5km away) next to my building, this all occurred within a few minutes (about 5).
Tonight i saw the moon (crescent) had again returned to its normal position.
Please explain the cause for this, i'm completely baffled!
(Sorry for the poor wording, i'm not familiar with all the astronomical terms!) The dull red color has been due to atmospheric causes, like the reddish sun close to sunset. There hasn't been an astronomical reason for the reddish color.
A few days after New Moon moonset occurs short after sunset, so you won't see the Moon high over the horizon at those evenings. With each day the Moon is a little higher above the horizon after sunset. It's hence less close to the horizon at the same time of the day. Less close to the horizon means less atomospheric absorption/scattering responsible for the dull red color, assuming the same weather conditions.
At Full Moon the Moon is at the opposite side of the Sun relative to Earth. Moon is then rising shortly after sunset.
The following is multiple choice question (with options) to answer.
What are the dark areas of the moon called? | [
"hollow space",
"laura",
"maria",
"craters"
] | C | The Moon has dark areas, called maria, surrounded by lighter colored highland areas, called terrae. |
SciQ | SciQ-4688 | water, mountains
Title: How do mountain springs get their water? I am curious how do mountain springs get their water. The water flowing from them eventually forms rivers.
Is it only from rain and snow? Or does water also come from underground-below the mountain (if so, then how does it "climb" to the spring which is at a high altitude)? Ultimately, it comes from precipitation. Ordinarily we think of rain as coming from low-level clouds, but Putkonen[1] has compiled rainfall data in the Himalayas showing significant rains up to several thousand meters altitude, covering the range where practically everyone lives. It is this precipitation that fills the underground tables mentioned by Jean-Marie Prival in a comment to the question.
Such a source is subject to the effects of climate change, which accordingly has led to significant environmental issues. See Ref [2].
References:
1.
Jaakko K. Putkonen, "Continuous Snow and Rain Data at 500 to 4400 m Altitude near Annapurna, Nepal, 1999–2001", Arctic, Antarctic, and Alpine Research, 36:2, 244-248 (2004)
2.
Sandeep Tambe, Ghanashyam Kharel, ML Arrawatia, Himanshu Kulkarni, Kaustubh Mahamuni, Anil K Ganeriwala,
"Reviving dying springs: climate change adaptation experiments from the Sikkim Himalaya",
Mountain Research and Development 32 (1), 62-72 (2012)
The following is multiple choice question (with options) to answer.
What do people use from aquifers from springs or wells? | [
"fresh water",
"soil",
"oxygen",
"salt"
] | A | People use fresh water from aquifers from springs or wells. |
SciQ | SciQ-4689 | evolution, mammals
Title: Why haven't land animals evolved beyond urination? It occurred to me (while urinating) that this would seem to be selected against because water is a scarce resource. Why are we constantly losing water we don't need to through urination? What is it about the chemistry of urine and the waste products eliminated that make urination necessary as opposed to eliminating them through defecation and recovering the water on the way out? It is probably true that toilets and other resting-ish area are always a great place to think about biology, I agree $\ddot \smile$.
Why do we urinate?
In short, urine contains the waste from our blood while defecation is just the stuff that we haven't digested. Kidneys are the organs responsible for draining wastes (mostly nitrogen-containing, or nitrogenous, wastes) from our blood.
Trade-off: energy cost vs. water loss
You're correct that the loss of water through urination is a considerable cost for an organism (especially those living in dry environments). But the amount of water used to excrete nitrogenous wastes is negatively correlated with the energy it costs to perform this excretion. In other words, there is a trade-off between water and energy loss during nitrogen excretion. Also, the question of toxicity is important.
Three ways to excrete nitrogenous wastes
Animals basically have three choices to excrete nitrogenous wastes:
Uric acid (excreted by uricotelic organisms)
Solid (crystal) with low water solubility
Low toxicity
Little water is needed
Lots of energy is needed
Ammonia (excreted by aminotelic organisms)
Highly soluble in water
High toxicity
Lots of water is needed to dilute it because of the toxicity
Not much energy is needed
Urea (excreted by ureotelic organisms)
Solid but highly soluble in water
"medium" amount of water is needed
"medium" toxicity
"medium" amount of energy is needed
The following is multiple choice question (with options) to answer.
What item lost by diffusion and in the urine are replenished by eating? | [
"sugar",
"protein",
"salt",
"yeast"
] | C | |
SciQ | SciQ-4690 | 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 is the primary cause of air movement in the troposphere? | [
"the ozone layer",
"differences in heating",
"solar winds",
"asteroids"
] | B | Air movement takes place in the troposphere. Air moves because of differences in heating. The differences create convection currents and winds. |
SciQ | SciQ-4691 | biochemistry
Alright so this is the oxidation of one mole of glucose equation (Without the ATPs) but till now I don't exactly know the correct answer for this question, but to not create any confusion this question is related to the Aerobic respiration (Glycolysis, Krebs Cycle and Electron transport chain).
Here's how I approached this question:
(a) is obviously not correct because the products of glycloysis are 2 pyruvate molecules and 2 ATP molecules so I checked off this choice.
(b) However seems correct because the products of 2 Krebs cycle is 4 CO2 and there is already 2CO2 when the pyruvate acid formed the 2 acetyl CoA molecules so in total that's 6CO2, but still what about the 6 Water molecules?
(c) is a very debating choice because when there is a "Complete occurrence of oxidative phosphorylation process" so that means 2 Krebs cycles had already occurred and formed the 6CO2, and during the oxidative phosphorylation process Water molecules are formed. and ATPs too? I don't exactly know about the ATPs, but aren't they supposed to be in the equation's products in order for this choice to be correct?
(d) This choice indicates to Krebs cycle but the water molecules only are formed during oxidative phosphorylation only.
So basically all the choices seems very debating and confusing and if I were to choose then I'll go with (C) because it's the only choice that makes sense for the water molecules (and the question asks for water), but I want someone to please answer this question with a brief explanation to why he chose this answer,
Thanks :) This reaction only means complete oxidation of glucose to 6 molecules of carbon dioxide and 6 molecules of water.
Reaction presented in question is very generalized, but the presence of six water molecules only means complete cellular respiration. Check out the actual biochemical pathways which take place to oxidize one glucose molecule.
And other options do not represent the complete cellular respiration, so there will not be formation of six water molecules, only option C means complete oxidation of glucose.
The following is multiple choice question (with options) to answer.
In cellular respiration, glucose is broken down and what is made? | [
"simple sugars",
"rna",
"chlorophyll",
"atp"
] | D | The flow of energy through living organisms begins with photosynthesis. This process stores energy from sunlight in the chemical bonds of glucose. By breaking the chemical bonds in glucose, cells release the stored energy and make the ATP they need. The process in which glucose is broken down and ATP is made is called cellular respiration . |
SciQ | SciQ-4692 | thermodynamics, energy, free-energy, molecular-dynamics
I think "total energy" would be the internal energy. It would be great if someone could please confirm/debunk that--I don't know if the situation is distinct for distinct ensembles, for example. Whatever the case, I don't know how it relates to the free energy. I would like to know if I have enough information to calculate the free energy.
If anyone could please point me in the right direction, I would appreciate it. I can't find anything online and maybe that's because I don't even know where to start looking. The sum of the potential and kinetic energies is the internal energy, E (or U).
However, you don't necessarily need to know the entropy to calculate the free energy. If you perform an equilibrium molecular dynamics simulation, you can derive the free energy from the equilibrium constant.
See, for instance:
https://onlinelibrary.wiley.com/doi/full/10.1002/jcc.21776
If you are modeling a constant T and V system, where there is no work done, the equilibrium constant would give you the Helmholtz free energy:
$$\Delta A = - R T ln K^{'}_{eq}$$
where A = E - TS
If you are modeling a constant T and p system, where you have no non-pV-work, the equilibrium constant would give you the Gibbs free energy:
$$\Delta G = - R T ln K^{''}_{eq}$$
where G = H - TS = E + pV - TS
The reason for this is that, at constant T and V, with no work term, minimizing A_sys corresponds to a maximization of S_univ, and thus determines the equilibrium condition. By contrast, at constant T and p, with pV-work only, minimizing G_sys corresponds to a maximization of S_univ, and thus determines the equilibrium condition.
I've marked the equilibrium constants as prime and double-prime to indicate that these would be numerically different.
The following is multiple choice question (with options) to answer.
The sum of the kinetic and potential energies of a system’s atoms and molecules is called what? | [
"internal energy",
"used energy",
"stored energy",
"mechanical energy"
] | A | Internal energy—the sum of the kinetic and potential energies of a system’s atoms and molecules. Can be divided into many subcategories, such as thermal and chemical energy. Depends only on the state of a system (such as its P , V , and T ), not on how the energy entered the system. Change in internal energy is path independent. |
SciQ | SciQ-4693 | thermodynamics, energy, energy-conservation, phase-transition, physical-chemistry
Title: Why is Energy change occurring during the reaction at constant temperature and constant volume given by internal energy change? When volume and temperature are kept constant, shouldn't internal energy remain constant (as it's a state function depending on state variables)? When heat is supplied, why does the internal energy increase if state variables are kept constant? For a system likely to be the seat of a chemical reaction, the variables of state are not limited to the temperature and the volume: it is necessary to add the extent of reaction.
The following is multiple choice question (with options) to answer.
After what state is reached, the concentrations of all reaction components remain constant unless a change is made to the system? | [
"equilibrium",
"homeostasis",
"equality",
"level"
] | A | After equilibrium has been reached, the concentrations of all reaction components will remain constant unless a change is made to the system. Because the concentrations are no longer changing, it may appear that the reaction has "stopped. " This is incorrect; both the forward and reverse reactions are still going on, even at equilibrium. However, because the two reactions are proceeding at the same rate, no net change is observed. |
SciQ | SciQ-4694 | evolution, reproduction, natural-selection, sex, gamete
Title: Are there multicellular isogamous species? Are there multicellular isogamous species?
Seeking through the examples of wikipedia I would tend to think that there are no multicellular isogamous species.
Our knowledge about the sexual transmission of mitochondria and
plastids (hereafter organelles) in isogamous eukaryotes comes mostly
from studies of the yeast Saccharomyces cerevisiae and the green alga
Chlamydomonas reinhardtii which are both unicellular species. To
investigate organelle inheritance in a multicellular organism with
morphological isogamy, we studied the filamentous brown alga
Ectocarpus siliculosus, in which each gamete contributes one plastid
and at least one mitochondrion to the zygote. ...
2004 - Inheritance of organelles in artificial hybrids of the isogamous multicellular chromist alga Ectocarpus siliculosus (Phaeophyceae)
So it is possible, but it seems like very rare.
The following is multiple choice question (with options) to answer.
What type of reproduction is exemplified by starfish and yeasts? | [
"sexual reproduction",
"asexual reproduction",
"bacteria reproduction",
"microscopic reproduction"
] | B | Starfish: Flickr:amanderson2; Yeast: Zappy's. Starfish and yeasts are examples of organisms that reproduce asexually . Starfish: CC BY 2.0; Yeast: CC BY-NC 3.0. |
SciQ | SciQ-4695 | energy, electrostatics, potential-energy
Title: where is electrostatic potential energy stored?
Potential energy can be defined as the capacity for doing work which arises from position or configuration.In the electrical case, a charge will exert a force on any other charge and potential energy arises from any collection of charges.
Where is this potential energy stored and how? That actually gets a bit tricky at the advanced level, but at the basic level, you should find somewhere in your textbook the equation $U = \int d^3x \left(\frac{1}{2} |\vec{E}|^2 \right)$ (maybe with a different constant up front, depending on what system of units the book is using). So at any point in space, the electric field $\vec{E}(\vec{x})$ at that point "stores" an amount of potential energy $\frac{1}{2} |\vec{E}|^2$.
The following is multiple choice question (with options) to answer.
What is the scientific term for stored energy an object has due to its position or shape? | [
"potential energy",
"new energy",
"repeat energy",
"mechanical energy"
] | A | Why do charges flow in an electric current? The answer has to do with electric potential energy. Potential energy is stored energy that an object has due to its position or shape. An electric charge has potential energy because of its position in an electric field. For example, when two negative charges are close together, they have potential energy because they repel each other and have the potential to push apart. If the charges move apart, their potential energy decreases. Electric charges always move spontaneously from a position where they have higher potential energy to a position where their potential energy is lower. This is similar to water falling over a dam from an area of higher to lower potential energy due to gravity. |
SciQ | SciQ-4696 | electricity, electric-circuits, electric-current, semiconductor-physics
Title: Why does current have to flow in the same direction? If current is just the movement of charged particles, why do the all have to move in the same direction?
For example, if you reverse-bias a diode (connect the positive terminal to the n-type side and the negative terminal to the p-type side), the positive "holes" are attracted to the negative terminal and the electrons are attracted to the positive terminal.
Firstly, if positive holes moving towards the negative terminal corresponds to electrons moving the opposite way (since "holes" aren't real, they're just a lack of electrons). So on both sides of the diode, electrons are moving in the same direction. I don't quite understand how this doesn't correspond to a current flowing.
Not even looking that deep into it, if positive charges are moving one way and negative charges the other, why does it matter if they cross the PN junction? Moving charges = electricity, right?
On top of all this, the battery creates an electric field that goes through all the wires, so why is there no current in the circuit? Electrons don't even move that fast (I've heard drift speed is on the order of cm/s), so "current" is localized in the sense that an electron on one side of a circuit may never even reach the other side. So why aren't localized electric fields enough to create a circuit? All charges don't move in the same direction. It's the net effect that we see. I think you're missing the fact that conventially current was thought to be the flow of positive charges.
Let's consider an example (something less complex than the diode example you've mentioned)
Consider an area element of a conductor and view it in a direction along its plane.
Let there be both positive and negative charges (yes, these are electrons (for a metallic conductor) but for the time being let them be positive and negative charges) to the left and right of the element.
The following is multiple choice question (with options) to answer.
What kind of current flows in just one direction? | [
"direct current",
"Alternating current",
"physical current",
"slow current"
] | A | When current flows in just one direction, it is called direct current (DC) . The diagram below shows how direct current flows through a simple circuit. An example of direct current is the current that flows through a battery-powered flashlight. In addition to batteries, solar cells and fuel cells can also provide direct current. |
SciQ | SciQ-4697 | (vii) Similarly as $0<\alpha<1$ rivers are horizontal.
Remark. Note the similarity to pendulum (see f.e. http://weyl.math.toronto.edu/MAT244-2011S-forum/index.php?topic=126.msg450#msg450) where there are "normal" oscillations and fast rotations when pendulum goes over top point.
« Last Edit: March 30, 2013, 05:22:58 AM by Victor Ivrii »
#### Alexander Jankowski
• Full Member
• Posts: 23
• Karma: 19
##### Re: Easter challenge
« Reply #9 on: March 29, 2013, 09:20:39 PM »
That is a good explanation. I also noted another of my mistakes... The equations of the separatrices are $$y = ±x + n\pi,$$ not $y = ±\pi x + n\pi$. Thank you!
The following is multiple choice question (with options) to answer.
Most motions in nature follow ________ rather than straight lines? | [
"sharp paths",
"vertical paths",
"horizontal paths",
"curved paths"
] | D | Introduction to Two-Dimensional Kinematics The arc of a basketball, the orbit of a satellite, a bicycle rounding a curve, a swimmer diving into a pool, blood gushing out of a wound, and a puppy chasing its tail are but a few examples of motions along curved paths. In fact, most motions in nature follow curved paths rather than straight lines. Motion along a curved path on a flat surface or a plane (such as that of a ball on a pool table or a skater on an ice rink) is two-dimensional, and thus described by two-dimensional kinematics. Motion not confined to a plane, such as a car following a winding mountain road, is described by three-dimensional kinematics. Both two- and threedimensional kinematics are simple extensions of the one-dimensional kinematics developed for straight-line motion in the previous chapter. This simple extension will allow us to apply physics to many more situations, and it will also yield unexpected insights about nature. |
SciQ | SciQ-4698 | energy, rotational-dynamics, work
Title: Work Done on a rotating body Hello so I am having an issue with a question I am trying to solve.
The following is multiple choice question (with options) to answer.
An object's energy due to motion is known as? | [
"thermodynamic energy",
"inertia",
"residual energy",
"kinetic energy"
] | D | An object’s kinetic energy is the energy due to motion. Kinetic energy can be defined mathematically as. |
SciQ | SciQ-4699 | mathematical-models, population-dynamics
Title: Range of feasible coefficients in an unlimited growth model If you are given an unlimited growth model in the form:
$\frac {dP(t)}{dt} = k P(t)$
Obviously the population growth would never be unlimited, but let's presume for the moment that we are introducing a species into an environment where there is the possibility for unlimited growth, at least on for a given time -- i.e. invasive species.
$k$ is some rate of growth of the population at time $t$, denoted by $P(t)$
What are some feasible values of $k$? In other words, if a number is way above or way below $k$, where would I know that the research I am reading is preposterously off-base?
I am sure it is different for different types of animals, including mammals, birds, bacteria, etc. A solid limit: k must be greater than zero. Unless you're talking about some cannibalistic species or something that isn't suited to the model at all.
As long as the species is productive in the new environment: k is greater than 1. The population is probably growing or again you probably won't be using an exponential growth model.
As mentioned before you would need to know the species for more information. But if you look at generation times and litter sizes:
Some bacterial generation times (from here) range from 10 to
2000 minutes (33 hours). So that is $k=2$ per generation time. Per
day you're looking at a lower bound of 2 per day and an upper bound
of $k=2^{14}=10^{43}$ per day.
Mice are something like 12 week generation time and a litter of 10
giving something like $k=10^{10}$ per year.
Elephants are one young every 25 years. So $k=16$ per century or so.
Of course this is all based on gross assumptions. But you're looking for guidelines for a unrealistic model so hopefully they'll do.
The following is multiple choice question (with options) to answer.
While populations with unlimited resources grow exponentially, the population of a species will level off when what limit of its environment is reached? | [
"reproduction",
"carrying capacity",
"niche",
"extinction"
] | B | 45.3 Environmental Limits to Population Growth Populations with unlimited resources grow exponentially, with an accelerating growth rate. When resources become limiting, populations follow a logistic growth curve. The population of a species will level off at the carrying capacity of its environment. |
SciQ | SciQ-4700 | group-theory
Title: Can you form a group with assembly instructions under the MIPS-32 architecture? Would it be possible to form such a group using the ADD instruction and the NOT instruction? Sure. The integers modulo $2^{32}$ form a group. The group operation is addition modulo $2^{32}$, which can be implemented by the ADD instruction. You don't need the NOT instruction.
There are other groups you could form, such as the integers modulo 2, and many more. I recommend you read the definition of a group and play around with some examples.
The following is multiple choice question (with options) to answer.
Group 16 is called what? | [
"noble gases",
"the oxygen group",
"metalloids",
"the acid group"
] | B | Group 16 is called the oxygen group. The first three elements in this group are nonmetals. They are followed by one metalloid and one metal. All the elements in the oxygen group have six valence electrons, and all are reactive. Oxygen (O), for example, readily reacts with metals to form compounds such as rust. Oxygen is a gas at room temperature. The other four elements in group 16 are solids. |
SciQ | SciQ-4701 | telescope, optics
Title: Shouldn't this cause a fire? This website shows a telescope projecting the sun onto a blackboard: https://astronomyconnect.com/forums/articles/2-three-ways-to-safely-observe-the-sun.21/
Why isn't the board catching fire? You can easily start a fire on a sunny day by targeting the focal point of a magnifying glass onto something flammable. Why isn't the telescope in this picture doing the same thing?
Photo by Luis Fernández García It could start a fire if the screen is at the focal point of the optical system. That is how you light fires with a magnifying glass.
Here, the blackboard is likely away from the focal point, so you can see the shape of the eclipse (and you get a bigger image) without setting things on fire.
Although this is fairly safe, there are a few things to pay attention to:
If you do this, make sure nobody can walk between the telescope and the screen, because if they go near the focal point, they could get very hot.
Doing this will cause your telescope to heat up. If there are any plastic parts, they can melt.
The telescope in the picture seems to have a small opening. Don't do this with a big telescope. You don't need to collect a lot of light.
Not an answer to the question, but an important note: Observing the Sun is the most hazardous thing you can do in astronomy. Make sure you know what you are doing before you try.
The following is multiple choice question (with options) to answer.
What type of temperatures increase the likelihood of fires? | [
"reduced",
"lower",
"freezing",
"higher"
] | D | |
SciQ | SciQ-4702 | co2, ocean-models, carbon-capture
Title: Can phytoplankton growth be stimulated in oceans to sequester CO2? Casual learner only.
Decades ago, I read, one ocean scientist stated, jokingly, probably, "Give me half a shipload of iron filings and I will give you another ice age." This was in response to the fact of iron being the only deficit in the southern ocean holding back phytoplankton growth. Some experiments did take place since then revealing a danger of toxic blooms and that the iron did not stay long enough in the upper ocean to have significant effect. But I find no continued investigations into stimulating phytoplankton growth despite it being such a major source of carbon absorption. Research into the topic has been intermittent for a variety of reasons. Ocean iron fertilization experiments – past, present, and future looking to a future Korean Iron Fertilization Experiment in the Southern Ocean (KIFES) project reviewed the status of research on the topic in 2018 and recommended ways the concept could be tested.
The "iron hypothesis" put forth by John Martin in 1990 was that iron dust carried into the ocean accelerated historic ice ages by fertilizing phytoplankton which then captured enormous volumes of carbon dioxide, reducing the greenhouse effect -- iron being a key nutrient for phytoplankton. The suggestion followed that one could combat modern global warming by artificially fertilizing oceans with iron filings.
The KIFES paper linked above and other sources suggest no credible scientific organization has wanted to conduct the large-scale experimentation and risk the potential ecological impacts and public disapproval to test out whether iron fertilization will have the desired sequestration effects, though some startups such as Blue Dot Change plan to try on their own, according to MIT Technology Review.
The following is multiple choice question (with options) to answer.
Fertilizer runoff can create what type of zones in the ocean? | [
"dead zones",
"barren zones",
"fresh zones",
"hot zones"
] | A | Fertilizer runoff can create dead zones in the ocean. |
SciQ | SciQ-4703 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
What kind of electricity can you generate with the energy found in flowing water? | [
"electrical power",
"transient power",
"hydroelectric power",
"wind energy"
] | C | The mechanical energy of rapidly flowing water can turn a turbine and generate electricity. Electricity produced in this way is called hydroelectric power. The water may flow over a waterfall or through a dam. You can see a picture of a dam in the Figure below . A drawback of dams is that they flood land upstream from the dam and reduce water flow downstream from the dam, and this can destroy ecosystems. At the following URL, you can learn more about hydroelectric power and see an animation of a hydroelectric power plant. |
SciQ | SciQ-4704 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
At the time of birth, bones of the brain case are separated by what wide areas of fibrous connective tissue, which later become sutures? | [
"fluctuations",
"sporozoans",
"fontanelles",
"cerebellum"
] | C | 7.5 Embryonic Development of the Axial Skeleton Formation of the axial skeleton begins during early embryonic development with the appearance of the rod-like notochord along the dorsal length of the early embryo. Repeating, paired blocks of tissue called somites then appear along either side of notochord. As the somites grow, they split into parts, one of which is called a sclerotome. This consists of mesenchyme, the embryonic tissue that will become the bones, cartilages, and connective tissues of the body. Mesenchyme in the head region will produce the bones of the skull via two different mechanisms. The bones of the brain case arise via intramembranous ossification in which embryonic mesenchyme tissue converts directly into bone. At the time of birth, these bones are separated by fontanelles, wide areas of fibrous connective tissue. As the bones grow, the fontanelles are reduced to sutures, which allow for continued growth of the skull throughout childhood. In contrast, the cranial base and facial bones are produced by the process of endochondral ossification, in which mesenchyme tissue initially produces a hyaline cartilage model of the future bone. The cartilage model allows for growth of the bone and is gradually converted into bone over a period of many years. The vertebrae, ribs, and sternum also develop via endochondral ossification. Mesenchyme accumulates around the notochord and produces hyaline cartilage models of the vertebrae. The notochord largely disappears, but remnants of the notochord contribute to formation of the intervertebral discs. In the thorax region, a portion of the vertebral cartilage model splits off to form the ribs. These then become attached anteriorly to the developing cartilage model of the sternum. Growth of the cartilage models for the vertebrae, ribs, and sternum allow for enlargement of the thoracic cage during childhood and adolescence. The cartilage models gradually undergo ossification and are converted into bone. |
SciQ | SciQ-4705 | inorganic-chemistry, bond, coordination-compounds
$^{[1]}$ More information can be found on Wikipedia and at RFW Bader's page at McMaster University. A more readable (but unfortunately paywalled) description is provided in Ref. [2].
$^{[2]}$Bader & Matta, Found Chem 15: 253 (2013). doi:10.1007/s10698-012-9153-1.
The following is multiple choice question (with options) to answer.
What are inorganic compounds that take the form of discrete molecules called? | [
"magnetic compounds",
"molecular compounds",
"ionic compounds",
"functional compounds"
] | B | Molecular compounds are inorganic compounds that take the form of discrete molecules . Examples include such familiar substance as water (H 2 O) and carbon dioxide (CO 2 ). These compounds are very different from ionic compounds like sodium chloride (NaCl). Ionic compounds are formed when metal atoms lose one or more of their electrons to nonmetal atoms. The resulting cations and anions are electrostatically attracted to each other. |
SciQ | SciQ-4706 | inorganic-chemistry, ions
Once you added a proton to the neutral ammonia molecule, you disturbed that original charge balance. There is a shortage of a single electron in the new molecule so formed and this denoted by the plus sign on the ammonium ion.
The following is multiple choice question (with options) to answer.
The other ammonium ions are changed into nitrogen gas by what? | [
"fluctuations bacteria",
"accompanying bacteria",
"fungi",
"denitrifying bacteria"
] | D | The other ammonium ions are changed into nitrogen gas by denitrifying bacteria. |
SciQ | SciQ-4707 | thermodynamics, climate-science
Title: Where does all the heat go during winter? I do not understand where actually the heat in our surroundings go during the winter season. Is it radiated out into space? I know it cannot coz global warming would not be a issue then. It might get absorbed but where? I tried figuring it myself but couldn't please help.
Where does all the heat go during winter?
There is less energy coming from the sun in the form of electromagnetic radiation impinging on the land during winter.
Depending on the latitude, in regions where there is winter , the difference is large.
The closer to the equator the smaller the effect of "winter".
So it is not where the energy goes, but why it does not fall , and this is explained to first order by the inclination and the distance to the sun during the orbit of the earth.
In general , a body in space radiates energy away the rate depending on various conditions, like green house gases, cloud cover, convection , albedo ...the numbers change . It is the continuous radiation from the sun that keeps replenishing the energy so that the earth does not freeze. During winter at high lattitutes , less energy comes and cold settles.
The following is multiple choice question (with options) to answer.
What is typical weather for chicago in winter? | [
"cold & snow",
"dry and windy",
"rain and wind",
"ice and humidity"
] | A | Cold and snow are typical for Chicago in the winter. |
SciQ | SciQ-4708 | redox
Footnotes:
Actually, you could also compare the standard reduction potentials of the reactions $\ce{Fe -> Fe^{2+} + 2e-}$ and $\ce{Cl- -> Cl^{.} + e-}$. The one that has the lower standard reduction potential is the winner (because the energy of a system is always minimized). This is also what you would usually do, but in this example it wasn't necessary because you could get to the solution via chemical concepts.
The following is multiple choice question (with options) to answer.
What works by providing a lower energy pathway from reactants to products? | [
"hormones",
"catalyst",
"magnetism",
"thermodynamics"
] | B | A catalyst works by providing a lower energy pathway from reactants to products. The use of a catalyst involves intermediate reactions which have lower activation complexes than the original reaction. On a simplified reaction energy diagram, this can be thought of as lowering the activation energy for a given transformation. If the activation energy of a reaction is decreased, more collisions will have enough energy to overcome this lower barrier, so the reactant-to-product transformation will occur more frequently. As a result, the overall reaction rate will be higher than for an identical reaction with a larger activation energy barrier. |
SciQ | SciQ-4709 | organic-chemistry
Title: find minimum value of p1+p2+p3+p4 where pi represents position of substituent and functional group in iupac name p1-bromo-p2-chloro-pent-p3-en-p4-one I have tried all I could for this question the answer I reached is 7 as in the attached pic but the book says 6 You can put Br and Cl in the same carbon. In 1-bromo-1-chloro-pent-1-en-3-one , p1+p2+p3+p4 is equal to 6. I think this is the smallest p1+p2+p3+p4 which can be reached according to IUPAC rules of nomenclature.
The following is multiple choice question (with options) to answer.
What is the smallest part of a compound? | [
"electron",
"dna",
"nucleus",
"molecule"
] | D | A compound is a substance that consists of two or more elements. A compound has a unique composition that is always the same. The smallest particle of a compound is called a molecule. |
SciQ | SciQ-4710 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
What layer of skin is located right beneath the epidermis? | [
"humus",
"cusps",
"dermis",
"scars"
] | C | The dermis is the lower layer of the skin, located directly beneath the epidermis (see Figure below ). It is made of tough connective tissue and attached to the epidermis by collagen fibers. The dermis contains blood vessels and nerve endings. Because of the nerve endings, skin can feel touch, pressure, heat, cold, and pain. The dermis also contains hair follicles and two types of glands. |
SciQ | SciQ-4711 | evolution, mammals, marine-biology
The question remains: why? The most likely explanation is that cetaceans evolved to exploit an unfilled ecological niche or adapted to new niches that formed as a result of plate tectonics or other types of environmental changes that occurred 50-55 million years ago. The niche describes all of the living and non-living resources needed by an organism to survive. Although land-based mammals were increasing in diversity, few or none were present in the oceans. The basic hypothesis is that the early whale-like artiodactyls, like Indohyus and Pakicetus were land-based (terrestrial) mammals that spent most of their time near the water's edge. Over time, they adapted to the niches in the ocean. Fossils like Ambulcetus and Rodhocetus showed clear evidence of swimming ability, with flattened tails and the enlarged rear feet. In addition, the nostrils shifted from the front of the face to the top of the head, which we recognize as the blowhole.
The shift to the aquatic habitat allowed these species to exploit resources that were not available to land-based mammals, thereby reducing competition for the resources. Reduced competition allows more individuals to survive and reproduce.
Similar scenarios are very likely for other marine mammals, such as seals or manatees. They evolved to take advantage of ecological niches that were not filled by other organisms. This basic concept, evolving to fill available niches, is a common outcome of the evolutionary process.
The of adaptation of cetaceans and other mammals to the oceans may be similar to that of the hippopotamus. Hippos spend most of their time in the water, and they show many adaptations that allow them to live in the aquatic environment. The eyes and nostrils of the hippo are high on the head, which allows them to remain almost entirely submerged but still see and smell, as shown below.
(Hippo photo by Johannes Lunberg, Flickr Creative Commons.)
Hippos feed underwaters, they are heavy enough to walk on the bottom of the river, and the mate and give birth underwater. The young can suckle underwater. Clearly, hippos seem to be another mammal that is "returning to water." Similar types of processes must have occurred in cetaceans for them to adapt to the marine habitat.
The following is multiple choice question (with options) to answer.
Some terrestrial species breathe through their skin and oral cavity because they lack what? | [
"nose",
"mouth",
"windpipe",
"lungs"
] | D | |
SciQ | SciQ-4712 | neuroscience, brain
Title: What is in the space between neurons in a brain? When neuron animations are displayed, there are frequently seen neurons, axons arranged in a lattice with a lot of empty space between. I'm interested if there is indeed empty space in the brain, or if it is filled with some sort of fluid? I've checked an article on cerebrospinal fluid but am not sure that it is present all throughout the brain.
The reason I'm asking is that I'm thinking of neurotransmitters- they are released in synapses, but I'm not sure how they stay there - are they suspended in some liquid as well? Not so empty, actually.
The human brain has a mass of ~1.5kg, and volume ~1200cc (a little bigger for men, a little smaller for women). So is heavier than water by a good margin.
While it has Cerebrospinal fluid, that only occupies the subarachnoid space (the space below the skull and above the cortex, contained between two layers: pia matter and arachnoid membrane) and the ventricular system (several spaces inside the brain, remnants of the embryological development of the brain).
Neuron density may vary widely, depending mainly on the particular characteristics of neuron cell types and their interconnections. But besides neurons, there's a lot of infrastructure inside the brain. For example:
Astroglia: They are a type of glial cells which participate in the formation of the blood-brain barrier (supporting the endothelial cells), nourishing of neurons, maintenance of ion and neurotransmitter concentrations, among others. They also keep in place most of the tissue.
Microglia: Small cells with immune (phagocitic) functions inside the brain.
Radial glia: A more specialized precursor cell, that also participates in neuronal migration in the brain.
Oligodendrocites: Cells responsible for the insulation (myelination) of axons.
Neuroepithelial cells: The stem cells in the brain.
The following is multiple choice question (with options) to answer.
What is the main type of cell in the nervous system called? | [
"sensory",
"conduction",
"axon",
"neuron"
] | D | Nervous Tissues Nervous tissues are made of cells specialized to receive and transmit electrical impulses from specific areas of the body and to send them to specific locations in the body. The main cell of the nervous system is the neuron, illustrated in Figure. |
SciQ | SciQ-4713 | 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.
Many ionic compounds occur as hydrates, compounds that contain specific ratios of loosely bound water molecules, called waters of hydration. waters of hydration can often be removed simply by doing this? | [
"melting",
"cooling",
"observing",
"heating"
] | D | Hydrates Many ionic compounds occur as hydrates, compounds that contain specific ratios of loosely bound water molecules, called waters of hydration. Waters of hydration can often be removed simply by heating. For example, calcium dihydrogen phosphate can form a solid that contains one molecule of water per Ca(H2PO4)2 unit and is used as a leavening agent in the food industry to cause baked goods to rise. The empirical formula for the solid is Ca(H 2PO4)2·H2O. In contrast, copper sulfate usually forms a blue solid that contains five waters of hydration per formula unit, with the empirical formula CuSO 4·5H2O. When heated, all five water molecules are lost, giving a white solid with the empirical formula CuSO 4 (Figure 2.9 "Loss of Water from a Hydrate with Heating"). |
SciQ | SciQ-4714 | neuroscience, brain, pain
Let's take stabbing as another cause of pain. One stab in a less dangerous place missing all important structures may be not that harmful but may be painful. However multiple small stabs into important structures like arteries or spinal cord could be horribly destructive.
Then let's look at headaches or nerve pain. Here it is only the pain and usually there isn't any destructive or harmful process. Most individuals would take one really, really bad headache followed by never having a headache then chronic daily "tension" headaches.
Psychologically though usually the chronic daily pain is the worst. Particularly as without adequate pain management from the start, it is less responsive to painkillers (analgesia). It frequently adds to depression if it does not cause it itself and can lead to suicide. Also painkillers themselves may cause chronic pain which does not help.
In summary, acute severe pain suggests something is seriously wrong and needs to be dealt with immediately biologically as there is likely a damaging process underlying it. However if this event is survived, it may be linked with high disability from any biological process that underpinned the pain. Chronic daily pain suggests a long continuing process. The cause of this may be life threatening, such as cancers, but is usually less dangerous at least compared to acute severe pain biologically. However the psychological aspects of this pain are seriously important as they can be particularly detrimental.
The following is multiple choice question (with options) to answer.
When blood vessels in the head dilate, what kind of severe headache can occur? | [
"malignant",
"chronic headache",
"migraine",
"tension headache"
] | C | A migraine is a more severe type of headache. It occurs when blood vessels in the head dilate, or expand. This may be triggered by certain foods, bright lights, weather changes, or other factors. People with migraines may also have nausea or other symptoms. Fortunately, migraines can often be relieved with prescription drugs. |
SciQ | SciQ-4715 | human-biology, cancer, medicine
Title: Why are only few cigarette smokers prone to cancer? It's tacit that only a few populace of smokers get cancer. What spares the others from it or what specifically cause cancer in those populace? See this Washington Post Article Cigarette smokers are most certainly prone to cancer. See Cecil Medicine, Chapter 183, on the epidemiology of cancer, exposure to tobacco is the most important environmental risk factor for cancer development, at least in the US:
Exposure to tobacco is the single largest cause of cancer in the United States... All forms of tobacco can cause cancer. Cigarette smoking causes cancer of the lip, oral cavity, nasal cavity, paranasal sinuses, pharynx (nasal, oral, and hypopharnyx), larynx, lung, esophagus (squamous cell and adenocarcinoma), stomach, colorectum, pancreas, liver, kidney (adenocarcinoma and renal pelvis), urinary bladder, uterine cervix, and myeloid leukemia.
Cancer may be identified or the cause of death in fewer smokers than might be expected, though, because smoking is an even greater risk factor for cardiovascular disease, and death due to cardiovascular disease.
Cancer is an unlikely phenomenon in an individual cell, but becomes more likely at the organism level, and even more likely over time. Though tobacco may be the most important environmental risk factor for cancer, age is actually a stronger predictor of cancer (see again, Cecil Chapter 183. Autopsy studies give us a quite remarkable example, this one shows incidental prostate cancer in nearly 60% of men over 80 who died from other causes. That figure is not out of the ordinary. Live long enough and you are likely to develop cancer.
Death due to heart disease may account for the lower than expected rates of cancer diagnoses and deaths in smokers. Nothing prevents cancer as well as dying from something else. And as discussed in the blog in the Washington Post you linked to, up to 2/3 of smokers die from smoking related causes
The following is multiple choice question (with options) to answer.
Acne and different types of cancer can affect what large organ? | [
"skin",
"liver",
"brain",
"lungs"
] | A | Common skin problems include acne and skin cancer. |
SciQ | SciQ-4716 | transcription, translation
Ralston, A. (2008) Operons and prokaryotic gene regulation. Nature Education
From Genes to Genomes: Concepts and Applications of DNA Technology
Molecular cell biology
Analysis of Genes and Genomes
The following is multiple choice question (with options) to answer.
Prokaryotic cells can only regulate gene expression by controlling the amount of what? | [
"RNA processing",
"folding",
"translation",
"transcription"
] | D | Evolution of Gene Regulation Prokaryotic cells can only regulate gene expression by controlling the amount of transcription. As eukaryotic cells evolved, the complexity of the control of gene expression increased. For example, with the evolution of eukaryotic cells came compartmentalization of important cellular components and cellular processes. A nuclear region that contains the DNA was formed. Transcription and translation were physically separated into two different cellular compartments. It therefore became possible to control gene expression by regulating transcription in the nucleus, and also by controlling the RNA levels and protein translation present outside the nucleus. Some cellular processes arose from the need of the organism to defend itself. Cellular processes such as gene silencing developed to protect the cell from viral or parasitic infections. If the cell could quickly shut off gene expression for a short period of time, it would be able to survive an infection when other organisms could not. Therefore, the organism evolved a new process that helped it survive, and it was able to pass this new development to offspring. |
SciQ | SciQ-4717 | equilibrium
Title: Why doesn't the ocean gradually turn into hydrogen and oxygen gas? Maybe I'm wrong about this, but I thought I remembered from high school chemistry that all reactions are in equilibrium. Some equilibria are extremely far to the right or left, so they appear to react 100% or not at all, but even in those reactions there is a tiny amount on the unfavored side.
If that's not true, then the answer to this question will be short. But if it is true, then I have a question about the following reaction, and bodies of water like lakes and oceans.
$$
\ce{2H2O (liquid) <=> 2H2 (g) + O2 (g)}
$$
If I remember right, the energy change ($\Delta{H}$ or $\Delta{G}$) in that reaction strongly favors the left side, so water molecules are not breaking apart into gas in large numbers. However, it's a gas on the right side, so I imagine that if a water molecule at the surface of the ocean breaks into gas, those products will escape, and the $\ce{H2}$ and $\ce{O2}$ gas molecules are no longer in physical contact and have no chance to react again.
That makes me think that gradually the ocean would turn into hydrogen and oxygen gas, even if the left side of that equation were favored. That doesn't seem to be happening, so what am I missing? I don't normally think there is hydrogen gas floating around in the air, but perhaps there actually is enough that some of it is colliding with $\ce{O2}$ at the ocean surface and balancing the equilibrium.
Maybe I'm wrong about this, but I thought I remembered from high school chemistry that all reactions are in equilibrium. Some equilibria are extremely far to the right or left, so they appear to react 100% or not at all, but even in those reactions there is a tiny amount on the unfavored side.
The following is multiple choice question (with options) to answer.
Where do oceans absorb gases from? | [
"wind",
"stratosphere",
"sunlight",
"atmosphere"
] | D | Oceans are an important part of the water cycle. They absorb gases from the atmosphere. They evaporate and supply water vapor to the atmosphere. |
SciQ | SciQ-4718 | human-biology, immunology
Title: Are there any viruses or bacteria which have evolved to withstand higher temperatures due to fever My question was raised after receiving this information:
The primary reason the body raises its temperature (via the Hypothalamus in this case) is that bacteria and viruses tend to optimally thrive at 98.6F, which is also your body's optimal operating temperature.
I am just wondering if there are any viruses or bacteria that have gained the ability to prosper under fever temperatures through evolution? If not, why not? Is there any biological restriction stopping such viral evolution?
Update:
I will try to explain my question. As far as I know, evolution helps species to adapt to their environment. For example, when people started using antibiotics we got new bacteria resistant to those antibiotics.
If fever is part of the innate immune reaction to viruses and bacteria, why hasn't this resulted in selection for fever-resistant variants? Why has evolution apparently stopped in this case? Fever is just one of the many ways of the body's defense mechanism work. Under infection, human body can raise body temperature, release cytokins and activate white blood cells etc. Sometimes the bacteria can evade immune suppression or immune complement fixation so that they can stay inside a "fever-ish" body like they just don't care. Example: Pseudomonas aeruginosa. They can grow in 42 degree Celsius which surpass the normal fever temperature.
My answer may not be the best for your question. All I'm trying to say is that fever acts as a supportive role during an infection. Human body relies on heavy artilleries such as white blood cells and cytokin to clear the infection. That's why it will be more beneficial for the bacteria to evolve abilities to evade immune suppression and immune complement fixation. And bacteria know how to do those.
The following is multiple choice question (with options) to answer.
Engaging in relatively simple behaviors helps maintain a nearly constant body temperature for organisms classified as what? | [
"placoderms",
"photophores",
"endotherms",
"ectotherms"
] | D | |
SciQ | SciQ-4719 | pharmacology
Title: Why is Benzylpenicillin better in Bacterial Meningitis than Amoxicillin? Both are beta lactams.
However, benzylpenicillin, which is also called penicillin G i.e. narrow group antibiotic.
I have now in both the following as a mechanism of action
Binds to PBP in bacterial cell wall, causing deficit in the cell wall and causing cell death.
where I would like to differentiate clearly benzylpenicillin from amocillin.
How is benzylpenicillin better in bacterial meningitis than amoxicillin? Amoxicillin is just penicillin with a hydroxyl group off the ring and an extra amine group..
Their mechanisms of action are the same. Their ability to cross the blood-brain barrier are the same. They can both cause seizures.
Both are used to treat to meningitis. The selection of one over the other would be based on the sensitivity of the infecting organism, and the ability to cross the blood-brain barrier in inflamed meninges.
There are better drugs to treat meningitis.
Penetration of Drugs through the Blood-Cerebrospinal Fluid/Blood-Brain Barrier for Treatment of Central Nervous System Infections
The following is multiple choice question (with options) to answer.
Meningitis is an infection of the membranes that cover the brain and what else? | [
"umbilical cord",
"notochord",
"liver",
"spinal cord"
] | D | Meningitis is an infection of the membranes that cover the brain and spinal cord. If you have meningitis, you are likely to have a fever and a headache. Another telltale symptom is a stiff neck. Meningitis can be caused by viruses or bacteria. Viral meningitis often clears up on its own after a few days. Bacterial meningitis is much more serious ( Figure below ). It may cause brain damage and death. People with bacterial meningitis need emergency medical treatment. They are usually given antibiotics to kill the bacteria. |
SciQ | SciQ-4720 | bacteriology, antibiotic-resistance, research-process
Title: How do scientists kill the bacteria they themselves made resistant? I was reading this article on researching bacteria resistance to silver by removing some of their genes.
Researchers then used "colony-scoring" software to measure the differences in growth and size of each plate's bacterial colony. E. coli strains with genes deleted involved in producing sensitivity, or toxicity, to silver grew larger colonies. Strains with genes deleted involved with resistance grew smaller colonies.
Once you end up with some resistant bacteria and you're done researching it, you can't just flush it down the toilet. How do you safely dispose those colony plates in a way that ensures those bacteria don't get out into the wild and reproduce? You are absolutely right, flushing down the toilet (or the sink) or simply throwing them into the normal waste doesn't work for biosafety reasons. And it is also not allowed, depending on the country you would do this in, this can lead to hefty fines.
Biologically contaminated lab waste can be inactivated (=all potential dangerous organisms are destroyed) by two ways: Either by heat or chemically. Which ways is used, depends on the kind of waste.
The most commonly used way is autoclaving, meaning treating the waste with steam at high temperatures at higher pressure. The temperature used here is usually 121°C, the exposure time depends on the volume of the waste, since the temperature needs to be reached and kept for at least 20 minutes. See the references for more details.
Liquid wastes (like culture media) can also be inactivated chemically by adding chlorine bleach to decompose the cells. Bleach can also be used to decontaminate surfaces, although here more often alcoholic solutions (70% Ethanol or Isopropanol) are used. After chemical inactivation, the remaining solutions should not be autoclaved as the emerging fumes are either unhealthy (bleach) or explosive (alcoholic solutions) and this is unnecessary, too.
Liquid wastes can also be autoclaved to inactivate them.
Autoclaving has the main advantage that it is rather simple (put the waste into the autoclave, close it and run a appropriate program), the waste can afterwards simply be discarded as normal waste, which may not be the case for chemically inactivated waste, which may need special precaution for disposal.
References:
The following is multiple choice question (with options) to answer.
What use enzymes to break down foreign matter and dead cells? | [
"lysosomes",
"lipids",
"hormones",
"lymphocytes"
] | A | Lysosomes, which use enzymes to break down foreign matter and dead cells. |
SciQ | SciQ-4721 | newtonian-mechanics
Title: What is the ratio of the acceleration in the two cases (a) and (b) What is the ratio of the acceleration in the two cases (a) and (b)?
I thought that the ratio would be 1:1 but it my textbook says its 1:3, so can someone explain to me how that's possible. $1)$ Let's make all the forces that would be acting on the blocks, in the first case.
Now we apply newtons' laws of motion assuming that block of mass 2m accelerates downward with $a_1$ acceleration and the block of mass m accelerates upward with same magnitude of $a_1$ acceleration( because they are constrained to have same acceleration till the string is tight).
So,
\begin{align}
&2mg-T=2ma_1\qquad\quad\cdots (1)\\
&T-mg=ma_1\qquad\qquad\cdots (2)\\
\end{align}
adding (1) and (2),
$$\implies(2mg-T)+(T-mg)=2ma_1+ma_1$$
$$\implies mg=3ma_1$$
$$\implies a_1=\frac{g}{3}\qquad\qquad\cdots(3)$$
Thus, acceleration of block of mass m would be $\frac{g}{3}$ in upward direction.
$2)$ Now making the forces for the second one:
The following is multiple choice question (with options) to answer.
What is indicated by the ratio of the output force to the input force in a machine? | [
"mechanical advantage",
"magnetic force",
"man hours",
"momentum"
] | A | The mechanical advantage of a machine is the factor by which the machine changes the input force. It equals the ratio of the output force to the input force. A wheel and axle may either increase or decrease the input force, depending on whether the input force is applied to the axle or the wheel. |
SciQ | SciQ-4722 | biochemistry, physiology, endocrinology
Title: What is the physiological difference between cortisone and cortisol? There is only hydrogen bond different.
Cortisol is synthesized by our body, while cortisone is given to the patient.
Why you cannot give cortisol directly to the patient?
I think the reason is metabolism that cortisol will break (probably in liver) and not be useful.
Or expansive to produce.
Cortisone however can be given.
What is the physiological difference between cortisone and cortisol? Cortisol is directly given to the patient - it is then called Hydrocortisone. I don't know why this is done but probably to avoid confusion because both names are too similar.
The difference between both forms is one hydrogen atom at the C11 position of the molecule in Cortisol (or Hydrocortison) (image from here):
Otherwise is Cortisol (or Hydrocortisone) the active version, while Cortisone isn't very active in the human body.
Both forms can enzymatically turned into the other form (from active to inactive and vice versa). Since Cortisone needs to be activated in the liver, it can only be used for oral uptake. Most of the uses which are colloquially called Cortisone in fact contain Hydrocortisone.
The following is multiple choice question (with options) to answer.
Glucocorticoids and mineralocorticoids are the two main types of what in humans? | [
"carotenoids",
"metabolites",
"hormones",
"corticosteroids"
] | D | |
SciQ | SciQ-4723 | solar-system, history
Earth at the center.
Moon orbiting the Earth.
Mercury orbiting the Earth farther than the Moon.
Venus orbiting the Earth farther than Mercury.
Sun orbiting the Earth farther than Venus.
Mars orbiting the Earth farther than Sun.
Jupiter orbiting the Earth farther than Mars.
Saturn orbiting the Earth farther than Jupiter.
The celestial sphere of stars rotating around the Earth, being the outermost sphere.
The following is multiple choice question (with options) to answer.
What keeps the earth orbiting the sun? | [
"magnetic force",
"weak nuclear force",
"strong nuclear force",
"gravity"
] | D | Earth and Moon orbit each other. This Earth-Moon system orbits the Sun in a regular path ( Figure below ). Gravity is the force of attraction between all objects. Gravity keeps the Earth and Moon in their orbits. Earth’s gravity pulls the Moon toward Earth’s center. Without gravity, the Moon would continue moving in a straight line off into space. |
SciQ | SciQ-4724 | communication, sociobiology, bees
Title: Waggle dance in the dark Karl von Frisch discovered waggle dance [1] as communication system when bees talk about feed resources;
Long story short, using a polar coordinate system, bees dance to reveal flowers to sisters.
My question is simple: how can this be possible since bees are in hives, which are dark?
That is, how can a bee sees its sister dancing in a dark hive?
[1] https://en.wikipedia.org/wiki/Waggle_dance In bees that dance in the dark (not all do, some dance in the light) they don't watch the dance, they participate. The follow the dancer using their antenna and sound to keep track of them.
Beehives are often dark, so instead of watching the scout dance, the recruit bees follow the dancer using their antenna and the sounds produced during the dance to determine the directions to the food source.
https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/waggle-dance#:~:text=The%20dance%20conveys%20information%20about,directions%20to%20the%20food%20source.
The following is multiple choice question (with options) to answer.
How do bees communicate to tell other bees where food is located? | [
"wing flapping",
"high pitch noise",
"waggle dance",
"mating dance"
] | C | Animals may communicate by sight with gestures, body postures, or facial expressions. Look at the cat in Figure below . There’s no mistaking the meaning of its arched back, standing hair, and exposed fangs. It’s clearly saying “stay away, or else!” Bees communicate with a waggle dance. They use it to tell other bees where food is located. |
SciQ | SciQ-4725 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Along with nerve tissue, what kind of tissue are lecithins and cephalins important constituents of? | [
"skin tissue",
"brain tissue",
"lung tissue",
"heart tissue"
] | B | (a) Amino alcohols are commonly found in phosphoglycerides, which are evident in its structural formula (b). There are two common types of phosphoglycerides. Phosphoglycerides containing ethanolamine as the amino alcohol are called phosphatidylethanolamines orcephalins. Cephalins are found in brain tissue and nerves and also have a role in blood clotting. Phosphoglycerides containing choline as the amino alcohol unit are called phosphatidylcholines or lecithins. Lecithins occur in all living organisms. Like cephalins, they are important constituents of nerve and brain tissue. Egg yolks are especially rich in lecithins. Commercial-grade lecithins isolated from soybeans are widely used in foods as emulsifying agents. An emulsifying agent is used to stabilize an emulsion—a dispersion of two liquids that do not normally mix, such as oil and water. Many foods are emulsions. Milk is an emulsion of butterfat in water. The emulsifying agent in milk is a protein called casein. Mayonnaise is an emulsion of salad oil in water, stabilized by lecithins present in egg yolk. Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-4726 | electromagnetic-radiation, radioactivity, x-rays
Title: Can one see radioactive substances with an X-ray detector? I was wondering the other day an X-ray detector (like the ones used at airports) can detect gamma-rays lets say from a sample of uranium. I know its all electro-magnetic waves but I'm really unsure about how it works in practical terms.
Edit
Now out of curiousity, if you got an beta-radiator, might that go unnoticed? Short answer to the title question: yes.
They are both species of ionizing photons, and you use the same set of mechanism to detect either band. Typically hodoscopes (perhaps based on fiber and high gain photo-diodes), multi-channel plates, or silicon strip detectors.
That said, I suspect that anna is right when she says that the machines used to scan luggage at the airport are not designed, or tuned to detect low levels of radioactivity (say kBq) in the baggage. The geometry that is most favorable for fast planar scanning will not be good at imaging a point source, and the designed flux is probably pretty high, meaning that weak sources only tweak the results by a little bit.
I have seen colloquia from people involved in designing large scale scanning machines for (shipping containers), and they but a great deal of thought and effort into the matter. Hand luggage is surely easier, but still non-trivial.
The following is multiple choice question (with options) to answer.
Metal detectors used for airport security work on which principle? | [
"inductance",
"electricity",
"inertia",
"conductivity"
] | A | One common application of inductance is used in traffic lights that can tell when vehicles are waiting at the intersection. An electrical circuit with an inductor is placed in the road under the place a waiting car will stop over. The body of the car increases the inductance and the circuit changes sending a signal to the traffic lights to change colors. Similarly, metal detectors used for airport security employ the same technique. A coil or inductor in the metal detector frame acts as both a transmitter and a receiver. The pulsed signal in the transmitter coil induces a signal in the receiver. The self-inductance of the circuit is affected by any metal object in the path. Such detectors can be adjusted for sensitivity and also can indicate the approximate location of metal found on a person. (But they will not be able to detect any plastic explosive such as that found on the “underwear bomber. ”) See Figure 23.43. |
SciQ | SciQ-4727 | botany, ecology, digestion, climate-change
The timing of residence times and flux rates (i.e., movement from one place to another) dictate whether a reservoir acts as a source or sink.
CO2 (carbon dioxide) and CH4 (methane) are quite different in the reactions from which they are generated (see Would fewer cows mean less methane emission?), the rate at which they are generated, and ultimately in their chemistry. This last point has drastic impacts on residence times, flux rates, and ultimately their their climate warming impacts:
Both molecules differ in their residence times in the atmosphere as well as their magnitude of radiative forcing. From MIT:
methane immediately begins to trap a lot of heat—at least 100 times as much as the CO2. But the methane starts to break down and leave the atmosphere relatively quickly. As more time goes by, and as more of that original ton of methane disappears, the steady warming effect of the CO2 slowly closes the gap. Over 20 years, the methane would trap about 80 times as much heat as the CO2. Over 100 years, that original ton of methane would trap about 25 times as much heat as the ton of CO2.
Note, also, that some of the atmospheric methane will eventually be chemically converted to carbon dioxide. From here.
Methane enters the atmosphere and eventually combines with oxygen (oxidizes) to form more CO2. Methane converts to CO2 by this simple chemical reaction.
Regarding methane production of cows and rates of release of greenhouse gasses, please see my other recently-answered BIO.SE post: Would fewer cows mean less methane emission?
Regarding carbon storage:
As stated above, understanding the carbon cycle requires both an understanding of residence times and flux rates. To determine the carbon storage ability of one biome or environment vs another, we typically measure the biomass of the organic matter (with interest in determining the C:N ratio) as well as flux rates in/out of our target carbon reservoir (e.g., plants such as crops or trees). Regarding flux rates, of particular interest are rates of carbon sequestration.
Ultimately, any community of plants that is capable of sequestering more carbon into large amounts of high-C:N biomass will result in larger carbon storage. The longer-lived those plants (i.e., the less labile their carbon), the longer that community of plants acts as a carbon sink.
The following is multiple choice question (with options) to answer.
Methanogens in their gut enable what process in cows? | [
"absorption",
"digestion",
"regeneration",
"excretion"
] | B | Cows are able to digest grass with the help of the methanogens in their gut. |
SciQ | SciQ-4728 | 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.
The skeleton of lampreys is made of what? | [
"collagen",
"chitin",
"ligament",
"cartilage"
] | D | |
SciQ | SciQ-4729 | reproduction
Title: Why are so many species reproducing late this year? Hope this question is OK for this site, couldn't see where else to ask it.
We've spent a few days out in the countryside recently, and have been very surprised at how many species appear to have very young offspring so late in the season. I was always under the impression that the vast majority of animals and fish produced young in the spring (March/April).
For example, we saw tadpoles, fluffy (ie obviously very young) coots and weeny minnows. I would have expected that all of these would have been born/laid a good 3 or 4 months ago, and so would be more mature by now.
Caveat: We didn't do a scientific study, this is just a strong impression we got from days out in north west England. It's hard to say without more information, but one substantial possibility is that you are mistaken that species are reproducing late - that's a problem with anecdotal rather than scientific data!
Additionally, species you mention like the common coot can attempt multiple broods where the season is long enough. Wikipedia specifically mentions Britain:
Eurasian coots normally only have a single brood each year but in some areas such as Britain they will sometimes attempt a second brood
The same could be true for species of frogs/toads and fish, so without knowing specific species it can't be known whether these are species reproducing again or species reproducing late.
The following is multiple choice question (with options) to answer.
How do amphibians reproduce? | [
"sexually",
"asexually",
"they don't",
"biologically"
] | A | Amphibians reproduce sexually. Fertilization may take place inside or outside the body. Amphibians are oviparous. Embryos develop in eggs outside the mother’s body. |
SciQ | SciQ-4730 | meteorology, weather-forecasting, united-states
Title: How is a weather forecast really done? I am trying to understand the concrete process of how a meteorologist at a weather forecast office produces the different types of weather forecasts.
I understand how numerical weather models work, but I would like to learn how the model output is turned into a forecast and to what extend it is improved by a skilled meteorologist.
I have found an older reference from 1993 that has some information on the workflow,
https://esrl.noaa.gov/gsd/eds/gfesuite/pubs/AWIPS-Forecast-Preparation-System.pdf
but this is probably outdated and doesn't talk about the meteorological side.
There are a lot of different forecast products from text to graphical products, so my question might be an overly broad one, but I haven't found much information so far, so I don't want to be too restrictive.
What concrete model outputs do forecasters look at and to what extend do they use local observations and experience? The National Weather Service actually has a nice forecast summary page that answers your question:
Our scientists thoroughly review current observations using technology such as radar, satellite and data from an assortment of ground-based and airborne instruments to get a complete picture of current conditions. Forecasters often rely on computer programs to create what’s called an “analysis,” which is simply a graphical representation of current conditions. Once this assessment is complete and the analysis is created, forecasters use a wide variety of numerical models, statistical and conceptual models, and years of local experience to determine how the current conditions will change with time. Numerical modeling is fully ingrained in the forecast process, and our forecasters review the output of these models daily. Often, the models yield different results, and in these circumstances, forecasters will determine which models perform best for the given situation or seek a blended solution.
They also have a good "About Page" that discusses the regional offices and a Virtual Tour of the Forecast Process.
The following is multiple choice question (with options) to answer.
What are scientists called who study the weather and give forecasts? | [
"climatologists",
"geologists",
"botanists",
"meteorologists"
] | D | People often complain when the weather forecast is wrong. Weather forecasts today, however, are much more accurate than they were just 20 years ago. Scientists who study and forecast the weather are called meteorologists. How do they predict the weather?. |
SciQ | SciQ-4731 | biochemistry, molecular-biology, receptor
Title: If a cell has two different GPCRs, how does the cell differentiate between the phosphorylation cascade caused by each? In my biochem course, we learned that GPCR receptors trigger a phosphorylation cascade, with the end result being a large amplification of the signal in the form of cAMP. We never studied any particular GPCR individually, but we were told that GPCRs always end in the formation of a large amount of cAMP, which will go on to phosphorylate key targets that achieve the end result.
My question is as follows: If there are two GPCRs on the same cell membrane (let's say GPCR-A and GPCR-B triggered by substrates A and B respectively), how does the cell "know" which GPCR triggered the phosphorylation cascade if the end result is the same (large amount of cAMP). In theory, couldn't substrate B bind to GPCR-B and cause a phosphorylation cascade identical to that of GPCR-A, thus triggering GPCR-A's cellular response?
Is there some deeper specialization/uniqueness to each type of GPCR receptor that we didn't cover in my course? Does each GPCR produce a slightly different cascade that ends in something similar, but not exactly cAMP? Or is there some restriction, like each cell limited to only one GPCR (I would find this surprising, if this is the case)? First, it would be an oversimplification to say that GPCRs act only through increases in cytosolic cAMP. This is true for receptors coupled to Gs proteins, but there are other G proteins like Gi, Go and Gq which act differently [1].
Now, a cell can have receptors coupled to many different G proteins. Vascular smooth muscle, for instance, has Gs, Gi and Gq-coupled receptors [2]. Further, a cell can have different receptors coupling to G proteins of the same type (e.g., hepatocytes have glucagon and beta adrenergic receptors [3], which both couple to Gs).
The following is multiple choice question (with options) to answer.
Autocrine signaling takes place within the same what? | [
"tissue type",
"organ",
"proteins",
"cell"
] | D | Other Types of Chemical Signaling In endocrine signaling, hormones secreted into the extracellular fluid diffuse into the blood or lymph, and can then travel great distances throughout the body. In contrast, autocrine signaling takes place within the same cell. An autocrine (auto= “self”) is a chemical that elicits a response in the same cell that secreted it. Interleukin-1, or IL-1, is a signaling molecule that plays an important role in inflammatory response. The cells that secrete IL-1 have receptors on their cell surface that bind these molecules, resulting in autocrine signaling. Local intercellular communication is the province of the paracrine, also called a paracrine factor, which is a chemical that induces a response in neighboring cells. Although paracrines may enter the bloodstream, their concentration is generally too low to elicit a response from distant tissues. A familiar example to those with asthma is histamine, a paracrine that is released by immune cells in the bronchial tree. Histamine causes the smooth muscle cells of the bronchi to constrict, narrowing the airways. Another example is the neurotransmitters of the nervous system, which act only locally within the synaptic cleft. |
SciQ | SciQ-4732 | dna, rna, virus, virology, gene
Title: Is there any virus that contains both DNA and RNA in its genome? It is known that viruses contain DNA or RNA- either one and not both.
I came across a question: Which virus contains both DNA and RNA? Here is the results summary of the study that describes the discovery of DNA:RNA hybrid virus:
Results
Bioinformatic analysis of viral metagenomic sequences derived from a hot, acidic lake revealed a circular, putatively single-stranded DNA virus encoding a major capsid protein similar to those found only in single-stranded RNA viruses. The presence and circular configuration of the complete virus genome was confirmed by inverse PCR amplification from native DNA extracted from lake sediment. The virus genome appears to be the result of a RNA-DNA recombination event between two ostensibly unrelated virus groups. Environmental sequence databases were examined for homologous genes arranged in similar configurations and three similar putative virus genomes from marine environments were identified. This result indicates the existence of a widespread but previously undetected group of viruses.
And here is the link to the paper:
https://biologydirect.biomedcentral.com/articles/10.1186/1745-6150-7-13
The following is multiple choice question (with options) to answer.
Both dna and rna are what type of acids? | [
"synthesize acids",
"fatty acids",
"nucleic acids",
"proteins acids"
] | C | DNA and RNA are nucleic acids. DNA stores genetic information. RNA helps build proteins. Proteins, in turn, determine the structure and function of all your cells. Proteins consist of chains of amino acids. A protein’s structure and function depends on the sequence of its amino acids. Instructions for this sequence are encoded in DNA. |
SciQ | SciQ-4733 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
What kind of a resource is soil, for human purposes? | [
"guarana resource",
"emanates resource",
"nonrenewable resource",
"renewable resource"
] | C | Although renewable, soil takes a very long time to form—up to hundreds of millions of years. So, for human purposes, soil is a nonrenewable resource. It is also constantly depleted of nutrients through careless use, and eroded by wind and water. For example, misuse of soil caused a huge amount of it to simply blow away in the 1930s during the Dust Bowl (see Figure below ). Soil must be used wisely to preserve it for the future. Conservation practices include contour plowing and terracing. Both reduce soil erosion. Soil also must be protected from toxic wastes. |
SciQ | SciQ-4734 | resources, soil
Title: Is soil a renewable resource? My geology textbook tells me that soil is not renewable, and I agree with this, but there was some question in my class as to whether this is true.
Some soils take more than a human lifetime to regenerate. However, in crop production, it seems as if soil can be regenerated with additives.
In the scientific community of soil scientists, is soil considered a renewable resource by most of those scientists? Is there strong evidence to support this? Soil is an interesting case because although it is non-renewable (at any useful rate) as a 'bulk material' once removed from the ground, the nutrient content of soil can be renewed with fertilizers.
What a soil-scientist would understand as 'soil' is ultimately produced from the physical and chemical breakdown of solid bedrock at the base of the soil horizon. The rate at which this happens for natural soil production can vary substantially depending on the climatic conditions and other factors, but typically could range from 0.1 to 2.0 mm/yr.
In many intensively farmed regions, (top)soil is being removed by erosion much faster than it is being replaced by natural process. Removal of vegetation cover is enough to expose bare soil to rainsplash erosion at rates much greater than it is renewed. Once soil is bare, it becomes much more susceptible to erosion.
I think the additives you are referring to replenish the nutrient content of the soil, and not the the bulk material that would be produced by bedrock decomposition. With careful management, the fertility of existing soil can be maintained. But if the soil is allowed to be washed off or erode, for all practical purposes, the rate of replenishment is not fast enough for it to be classed as renewable in that sense.
This site has links to more aspects surrounding this issue.
The following is multiple choice question (with options) to answer.
A natural resource that is consumed or used up faster than it can be made by nature is termed what? | [
"renewable",
"energy-inefficient",
"fossil fuel",
"non-renewable"
] | D | A nonrenewable resource is a natural resource that is consumed or used up faster than it can be made by nature. Two main types of nonrenewable resources are fossil fuels and nuclear power. Fossil fuels , such as petroleum, coal, and natural gas, formed from plant and animal remains over periods from 50 to 350 million years ago. They took millions of years to form. Humans have been consuming fossil fuels for less than 200 years, yet remaining reserves of oil can supply our needs only until around the year 2055. Natural gas can only supply us until around 2085. Coal will last longer, until around the year 2250. That is why it is so important to develop alternate forms of energy, especially for our cars. Today, electric cars are becoming more and more common. What would happen if we ran out of gasoline? Alternative use of energy, especially in transportation, must become a standard feature of all cars and trucks and planes by the middle of the century. |
SciQ | SciQ-4735 | electromagnetism, energy, electric-circuits, integration
Title: Electromagnetic converters, differentials and integrals In the context of electromagnetic converters, a converter can be modeled by a system that receives electrical energy and outputs mechanical energy. At some point in my textbook, the authors present the following differential that represents a small change in the co-magnetic energy of the system:
$$ \mathrm dW_\mathrm{cmag} = \sum_{k=1}^n \phi_k di_k$$
where $\phi_k = \phi_k(i_1,i_2,...,i_n)$ the total flux generated by the currents $i_1,...,i_n$ in the $k$th winding/coil that is part of the system. $W_\mathrm{cmag}$ represents a co-magnetic energy of the system (state function). $\mathrm dW_\mathrm{cmag}$ is then simply a small change in the system's co-magnetic energy. They then do something that I'm not sure I understand, that is how they integrate $dW_\mathrm{cmag}$ in order to get $W_\mathrm{cmag}$:
$$W_\mathrm{cmag} = \int_{0,0,\ldots,0}^{i_1,i_2,\ldots,i_n} \sum_{k=1}^n \phi_k \mathrm di_k$$
The following is multiple choice question (with options) to answer.
An electrical motor changes electrical energy into what? | [
"chemical energy",
"thermal energy",
"solar energy",
"mechanical energy"
] | D | Electrical motors change electrical energy into mechanical energy. The motor consists of an electrical circuit with part of the wires inside a magnetic field. This can be seen below. Positive charges move through the circuit in the direction of the light purple arrows. When the charges move up through the part of the coil that is right next to the north pole, the right hand rule tells us that the wire suffers the force, F , pushing the wire in the direction of the blue arrow, toward the back of the sketch. On the other side of the coil, where the charges are moving down through the field, the right hand rule shows the force would push this side of the coil toward the front. These two forces are working together, rotating the coil in the direction of the circular red arrow. |
SciQ | SciQ-4736 | pathology
Title: Are abrasions considered closed wounds? A closed wound is one where skin is intact and underlying tissue is not exposed to the environment.
Abrasion is an erosion of skin usually due to sheering force. In most cases the dermis is intact and the injury is superficial limited to epidermis. Abrasions heal without scarring by epithelialization.
Are abrasions considered closed wounds? I would think they are open wounds as the underlying tissue (which would be dermis in this case) are exposed to the environment. Please state the reason why they are classified into whatever group. The definition of closed and open wounds is variable. In histopathological terms (i.e. looking under a microscope) it is usually defined that a wound where the dermis is affected is open. In this case an abrasion is an open wound. This puts it in the same class as cuts (incisional/lacerations), tears and punctures. Closed wounds on the other hand are when the dermis isn't affected, such as in a haematoma (blood collection under the skin) or crush injury (extreme force typically for a long period of time) and contusions (i.e. bruises).
Medically they may be divided by management. Where open wounds are wounds which are likely to be contaminated and need thorough cleaning and may need antibiotic cover whereas closed wounds are ones that are very unlikely to be. In this case, abrasions may be considered a relatively closed wound as not all the protective layers of the skin have been breached (the dermis is not completely breached). Thus the physical barriers are relatively intact and continue to offer us defense against bacteria and organisms.
The following is multiple choice question (with options) to answer.
What is name for a piece of collagen-rich skin formed after the process of wound healing that differs from normal skin? | [
"tissue",
"scar",
"Sore",
"size"
] | B | Scars and Keloids Most cuts or wounds, with the exception of ones that only scratch the surface (the epidermis), lead to scar formation. A scar is collagen-rich skin formed after the process of wound healing that differs from normal skin. Scarring occurs in cases in which there is repair of skin damage, but the skin fails to regenerate the original skin structure. Fibroblasts generate scar tissue in the form of collagen, and the bulk of repair is due to the basket-weave pattern generated by collagen fibers and does not result in regeneration of the typical cellular structure of skin. Instead, the tissue is fibrous in nature and does not allow for the regeneration of accessory structures, such as hair follicles, sweat glands, or sebaceous glands. Sometimes, there is an overproduction of scar tissue, because the process of collagen formation does not stop when the wound is healed; this results in the formation of a raised or hypertrophic scar called a keloid. In contrast, scars that result from acne and chickenpox have a sunken appearance and are called atrophic scars. Scarring of skin after wound healing is a natural process and does not need to be treated further. Application of mineral oil and lotions may reduce the formation of scar tissue. However, modern cosmetic procedures, such as dermabrasion, laser treatments, and filler injections have been invented as remedies for severe scarring. All of these procedures try to reorganize the structure of the epidermis and underlying collagen tissue to make it look more natural. |
SciQ | SciQ-4737 | cell-biology, gene-expression, development, embryology
I'm reluctant to go into too much detail on this because you're asking about a complex process that is still under active study and I'm unclear as to how much information you actually want. A book could be written on this subject alone, and many review papers have been published. Here's a recent one:
Development: Do Mouse Embryos Play Dice?
I suggest you read that and then if you have further, more specific questions, we can try and answer them for you.
The following is multiple choice question (with options) to answer.
Young eutherians complete their embryonic development within what? | [
"ovaries",
"uterus",
"spores",
"pollen grains"
] | B | |
SciQ | SciQ-4738 | thermodynamics, nuclear-physics, nuclear-engineering, binding-energy
Title: How is energy actually extracted from fission? Every source I can find right now just says something like 'energy/ heat is released by nuclear fission' but I can't find a description of the specific mechanism.
I know that the energy 'conversion' so to speak is from 'nuclear' [in the mother nucleus] to 'thermal' [in the coolant (water)], but I'm looking for an understanding of what's happening on a fundamental level.
I know that the daughter nuclei and free neutrons will have kinetic energy. Is this then transferred to the water via atomic collisions?
Do the gamma rays help to heat the water? If so, how? When an isotope fissions, it releases somewhere between 2-3 fast neutrons, prompt gamma rays, and usually two fission products. The fission products are radioactive, and some of the fission product decay releases additional energy in the form of beta rays, gamma rays, and neutrinos.
Most of the energy (about 80 percent) is released as kinetic energy of the fission products, which causes the nuclear fuel to heat up. In most commercial reactors, water flows through the core to remove the heat from the fuel, and the water is used to produce steam for a turbine.
There are several different sources for exactly how much energy is released. In the book "Nuclear Reactor Theory", by J. R. Lamarsh (1966), the following table is given:
Fission fragments 168 MeV
Fission product decay
beta rays 8 MeV
gamma rays 7 MeV
neutrinos 12 MeV (this energy cannot be recovered)
prompt gamma rays 7 MeV
Fission neutrons 5 MeV
Total 207 MeV
More up-to-date data can be found in the ENDF/B data, but it is fairly close to the table shown above.
The following is multiple choice question (with options) to answer.
Nuclear reactors use fission reactions to vaporize water, producing steam to drive a turbine and generate what? | [
"light",
"electricity",
"fuel",
"oil"
] | B | Nuclear reactors use fission reactions to vaporize water. The resulting steam is used to drive a turbine, which generates electricity. |
SciQ | SciQ-4739 | plant-physiology, botany
Title: Do plants produce any heat? Many plants (e.g. roses, palms) can be protected from frost during the winter if shielded with an appropriate coat that can be bought in garden shops. Do plants produce any heat that can be kept inside with these "clothes"? Cellular respiration in plants is slightly different than in other eukaryotes because the electron transport chain contains an additional enzyme called Alternative Oxidase (AOX). AOX takes some electrons out of the pathway prematurely - basically the energy is used to generate heat instead of ATP.
The exact purpose of AOX in plants is still unclear. Plants will make more AOX in response to cold, wounding, and oxidative stress. We know of at least one plant (skunk cabbage) that exploits this pathway to generate enough heat to melt snow. This link gives a pretty good overview.
(AOX is dear to my heart, since my first 3 years working in a laboratory were spent studying this gene <3)
The following is multiple choice question (with options) to answer.
What type of air do plants take in and use? | [
"oxygen",
"carbon dioxide",
"liquid dioxide",
"carbon"
] | B | |
SciQ | SciQ-4740 | spectroscopy
Even here there are a few caveats. You definitely don't want giant stars (too much turbulence and distortions), but luckily, most of them are in the main sequence.
Lastly, be warned, automatic processing of spectra (extracting lines and so on) is not as simple as one may wish, or think.
Edit:
If you want to avoid reducing spectra all together, you can just query for the redshifts of stars (say they are brighter than a certain magnitude). You will need accuracy of $10^{-4}$, and it seems to be provided.
Problem: you need to write a SQL query, but there are several examples that you can just copy and strip down to your need (most astronomers are not advanced programmers anyway and they mange), or just as at SO.
A very nice project idea! I wonder how far can you push it.
The following is multiple choice question (with options) to answer.
How long can a large star be on the main sequence stage? | [
"3 million years",
"200.4 million years",
"10 million years",
"60.11 million years"
] | C | Large stars burn through their supply of hydrogen very quickly. These stars “live fast and die young!” A very large star may only be on the main sequence for 10 million years. A very small star could remain on the main sequence for tens to hundreds of billions of years—far longer than the current age of our Universe. |
SciQ | SciQ-4741 | optics, geometric-optics
Title: Dispersion of light by triangular prism A glass prism is able to produce a spectrum when white light passes through it but a glass slab does not produce any spectrum.Explain the reason.
now in a glass slab light passes normally and i think so there is no dispersion. The main reason you can see a spectrum in the prism is that light of different wavelength will go in different directions.
For a glass plate, any refraction caused to the light as it goes into the glass will be reverted when it goes out, causing all wavelength to travel in the same direction again.
The following is multiple choice question (with options) to answer.
What do you call the pattern of lines formed when light passes through a prism to separate it into the different frequencies of light it contains? | [
"atomic emission spectrum",
"light emission spectrum",
"kaleidoscope effect",
"prismatic rainbow"
] | A | Scientists studied the distinctive pink color of the gas discharge created by hydrogen gas. When a narrow beam of this light was viewed through a prism, the light was separated into four lines of very specific wavelengths (and frequencies since and are inversely related). An atomic emission spectrum is the pattern of lines formed when light passes through a prism to separate it into the different frequencies of light it contains. The Figure below shows the atomic emission spectrum of hydrogen. |
SciQ | SciQ-4742 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
What is the term for a watertight seal between two adjacent animal cells? | [
"cell wall",
"cell membrane",
"placental barrier",
"tight junction"
] | D | A tight junction is a watertight seal between two adjacent animal cells (Figure 3.17b). Proteins hold the cells tightly against each other. This tight adhesion prevents materials from leaking between the cells. Tight junctions are typically found in the epithelial tissue that lines internal organs and cavities, and composes most of the skin. For example, the tight junctions of the epithelial cells lining the urinary bladder prevent urine from leaking into the extracellular space. Also found only in animal cells are desmosomes, which act like spot welds between adjacent epithelial cells (Figure 3.17c). They keep cells together in a sheet-like formation in organs and tissues that stretch, like the skin, heart, and muscles. Gap junctions in animal cells are like plasmodesmata in plant cells in that they are channels between adjacent cells that allow for the transport of ions, nutrients, and other substances that enable cells to communicate (Figure 3.17d). Structurally, however, gap junctions and plasmodesmata differ. |
SciQ | SciQ-4743 | cell-biology
Title: Structure of Cell Are cells spheres or ovals/circles bound by phospholipidbilayer?
If they are spherical how are we able to see the nucleus through the phospholipid bilayer under a microscope? Not exactly. That is a stereotype of cells. Muscle cells are not round nor oval, but rather elongated rods. If you were to look up epithelia cells, you can quickly see that cells are grouped based on their physical characteristics; simple (round/oval & single layer), columnar, and cuboidal to name a few. Cells come in many shapes and sizes. As Hans stated, stains are vital in viewing cellular components. There is a diverse amount of stains used - which all carry a purpose and benefit in a specific application.
The following is multiple choice question (with options) to answer.
What is at the surface of a cell, arranged in similar bilayer? | [
"fats",
"phospholipids",
"eukaryotes",
"pigments"
] | B |
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