source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3544 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
What are the three types of rocks? | [
"igneous, sedimentary, mixed",
"opaque , sedimentary , metamorphic",
"igneous, sedimentary, metamorphic",
"igneous, orbital, metamorphic"
] | C | You learned about the three rock types: igneous, sedimentary, and metamorphic. You also learned that all of these rocks can change. In fact, any rock can change to become any other type of rock. These changes usually happen very slowly. Some changes happen below Earth’s surface. Some changes happen above ground. These changes are all part of the rock cycle. The rock cycle describes each of the main types of rocks, how they form, and how they change. |
SciQ | SciQ-3545 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
How do yeasts reproduce asexually? | [
"by synchronizing",
"by outcropping",
"by merging",
"by budding"
] | D | Yeasts do not produce spores. Instead, they reproduce asexually by budding. Budding is the pinching off of an offspring from the parent cell. The offspring cell is genetically identical to the parent. Budding in yeast is pictured in Figure below . |
SciQ | SciQ-3546 | python, pybedtools, pyranges
# | chr1 | 749686 | 749697 | 180.0 | + | 749277 | 759277 | - | 6395 |
# | ... | ... | ... | ... | ... | ... | ... | ... | ... |
# | chrY | 59060667 | 59060767 | 196.0 | - | 59052942 | 59062942 | - | 99957 |
# | chrY | 59060667 | 59060767 | 196.0 | - | 59059904 | 59069904 | + | 98401 |
# | chrY | 59063570 | 59063576 | 105.0 | - | 59059904 | 59069904 | + | 98401 |
# | chrY | 59269010 | 59269085 | 152.0 | - | 59264704 | 59274704 | - | 99499 |
# +--------------+-----------+-----------+-------------+------------+-----------+-----------+--------------+-----------+
# Stranded PyRanges object has 106,643 rows and 9 columns from 25 chromosomes.
# For printing, the PyRanges was sorted on Chromosome and Strand.
The following is multiple choice question (with options) to answer.
How many chromosomes are in each set? | [
"13",
"22",
"21",
"23"
] | D | Human cells normally have two sets of chromosomes, one set inherited from each parent. There are 23 chromosomes in each set, for a total of 46 chromosomes per cell. Each chromosome in one set is matched by a chromosome of the same type in the other set, so there are actually 23 pairs of chromosomes per cell. Each pair consists of chromosomes of the same size and shape that also contain the same genes. The chromosomes in a pair are known as homologous chromosomes . |
SciQ | SciQ-3547 | inorganic-chemistry, electrochemistry, corrosion
Title: Does iron rust because of impurities found in it (ex. carbon)? If we, theoretically, get a piece of ideally 100% pure iron and it is left in moist air? Will it rust? My understanding of iron rust is that the Iron itself becomes the ANODE and carbon impurities (as an example of impurities) are CATHODE, so if this cathode is not there will iron itself become anode and cathode and rust? Three substances are required to transform iron into rust : air (oxygen), water, and a impurity at the surface of the metal. If one of these substances is missing, iron will not rust. The whole operation occurs at the contact of the impurity and iron and it has an electric origin. The reduction occurs at the impurity working as a cathode. It is well described in N. N. Greenwood and E. Earnshaw, Chemistry of the Elements, Pergamon 1983, p.1250
The following is multiple choice question (with options) to answer.
Iron is oxidized to fe2+(aq) at an anodic site on the surface of the iron, which is often an impurity or this? | [
"lattice defect",
"displacement defect",
"ladder complex",
"spontaneous mutation"
] | A | Iron is oxidized to Fe2+(aq) at an anodic site on the surface of the iron, which is often an impurity or a lattice defect. Oxygen is reduced to water at a different site on the surface of the iron, which acts as the cathode. Electrons are transferred from the anode to the cathode through the electrically conductive metal. Water is a solvent for the Fe2+ that is produced initially and acts as a salt bridge. Rust (Fe2O3·xH2O) is formed by the subsequent oxidation of Fe2+ by atmospheric oxygen. In the corrosion process, iron metal acts as the anode in a galvanic cell and is oxidized to Fe2+; oxygen is reduced to water at the cathode. The relevant reactions are as follows:. |
SciQ | SciQ-3548 | dna, chromosome
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
But Why does DNA need to be coiled tightly into chromosomes?
DNA double helix is like a telephone wire. If length is to be measured, it will go beyond 60 miles. Some even say it can make a trip to the moon more than 150,000 times. Such a long DNA molecule is not only the part of each organism's cell nucleus but also it's invisible to the naked eye. This happens just because of the high packaging and coiling of this long DNA molecule.
Let's see the diagram to get an idea.
At the bottom of the diagram there is a sequence of nucleotides (ATGC) in different combinations. This can be considered as a gene if it codes for certain protein which is required for the growth or any other function of the body.
Returning back to your question, Complimentary base pairs are not genes.
Genes are the segments of DNA which is a long sequence of nucleotide base pairs that code for any protein or RNA transcript that contributes to any trait/phenotype/function of an individual.
With the tight packaging of DNA double helix along with help of packaging proteins(Histones and Non-histones), the chromatid and chromosomes are made. The packaging of DNA to chromosomes is highly controlled and is a whole different topic in itself.
The following is multiple choice question (with options) to answer.
Each species has a characteristic number of what coiled structures made of dna and proteins? | [
"chromosomes",
"prokaryotes",
"ribosomes",
"genes"
] | A | Each species has a characteristic number of chromosomes. Chromosomes are coiled structures made of DNA and proteins called histones ( Figure below ). Chromosomes are the form of the genetic material of a cell during cell division. See the "Chromosomes" section for additional information. |
SciQ | SciQ-3549 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What is the name for tiny animals that feed on phytoplankton? | [
"jellyfish",
"krill",
"zooplankton",
"larvae"
] | C | Plankton are tiny aquatic organisms that cannot move on their own. They live in the photic zone. They include phytoplankton and zooplankton. Phytoplankton are bacteria and algae that use sunlight to make food. Zooplankton are tiny animals that feed on phytoplankton. |
SciQ | SciQ-3550 | human-biology, physiology, metabolism
Thus, carbon dioxide (in the form of bicarbonate) is an obligate requiement for mammalian fatty acid biosynthesis, but no CO2-derived carbon is incorporated into fatty acids.
Carbon dioxide is also required for oxaloacetate formation from pyruvate. This reaction may be though of a method of 'filling up' a key Krebs Cycle intermediate (a so-called anapleurotic reaction). The enzyme here is pyruvate carboxylase and the substrates for the reaction are pyruvate, bicarbonate and ATP, with oxaloacetate being a key product. This enzyme also contains biotin and (like acetyl CoA carboxylase), CO2 becomes covalently bound to biotin during the reaction cycle.
Pyruvate-CoA carboxylase was discovered by Harland.G Wood and C. Werkman in bacteria (See here for a good reference on the early work on pyruvate carboxylase). Its discovery was very controversial because at the time it was thought that animal/bacterial cells could not 'fix' CO2; that is it was though that CO2 is only 'fixed' in photosynthesis. This discovery disproved that piece of dogmatism.
A third enzyme that requires CO2 as substrate (in the form of bicarbonate) is propionyl-CoA carboxylase. This enzyme occurs in mitochondria and functions in odd-chain fatty acid metabolism. It also contains biotin.
I have concentrated on some biochemical aspects of your question. The three enzymes mentioned, acety-CoA carboxylase, pyruvate carboxylase and propionyl-CoA carboxylase all require CO2 in the form of bicarbonate as substrate, all contain biotin, and (as far as I am aware) all play very central roles in mammalian metabolism. (They also all require ATP as substrate).
The following is multiple choice question (with options) to answer.
What do marine autotrophs acquire in carbonic acid, its dissolved form? | [
"carbon monoxide",
"chlorine dioxide",
"silicon dioxide",
"carbon dioxide"
] | D | The Biological Carbon Cycle Living organisms are connected in many ways, even between ecosystems. A good example of this connection is the exchange of carbon between heterotrophs and autotrophs within and between ecosystems by way of atmospheric carbon dioxide. Carbon dioxide is the basic building block that autotrophs use to build multi-carbon, high-energy compounds, such as glucose. The energy harnessed from the Sun is used by these organisms to form the covalent bonds that link carbon atoms together. These chemical bonds store this energy for later use in the process of respiration. Most terrestrial autotrophs obtain their carbon dioxide directly from the atmosphere, while marine autotrophs acquire it in the dissolved form (carbonic acid, HCO3–). However the carbon dioxide is acquired, a byproduct of fixing carbon in organic compounds is oxygen. Photosynthetic organisms are responsible for maintaining approximately 21 percent of the oxygen content of the atmosphere that we observe today. The partners in biological carbon exchange are the heterotrophs (especially the primary consumers, largely herbivores). Heterotrophs acquire the high-energy carbon compounds from the autotrophs by consuming them and breaking them down by respiration to obtain cellular energy, such as ATP. The most efficient type of respiration, aerobic respiration, requires oxygen obtained from the atmosphere or dissolved in water. Thus, there is a constant exchange of oxygen and carbon dioxide between the autotrophs (which need the carbon) and the heterotrophs (which need the oxygen). Autotrophs also respire and consume the organic molecules they form: using oxygen and releasing carbon dioxide. They release more oxygen gas as a waste product of photosynthesis than they use for their own respiration; therefore, there is excess available for the respiration of other aerobic organisms. Gas exchange through the atmosphere and water is one way that the carbon cycle connects all living organisms on Earth. The Biogeochemical Carbon Cycle The movement of carbon through land, water, and air is complex, and, in many cases, it occurs much more slowly geologically than the movement between living organisms. Carbon is stored for long periods in what are known as carbon reservoirs, which include the atmosphere, bodies of liquid water (mostly oceans), ocean sediment, soil, rocks (including fossil fuels), and Earth’s interior. |
SciQ | SciQ-3551 | reproduction, asexual-reproduction
Title: can self-fertilization in flowers be called asexual reproduction? Suppose a flower having both male and female reproductive parts is self-fertilized then can this be called asexual reproduction...?I'm quite confused cause in this case the fusion of male and female gametes do take place but again the gametes are from the same parent....please help. According to this article from Berkeley, asexual reproduction is:
Any reproductive process that does not involve meiosis or syngamy
Using this definition of asexual reproduction and knowing self-fertilization involves meiosis and syngamy, it is not asexual.
The following is multiple choice question (with options) to answer.
Asexual, sexual, budding, and parthenogenesis are all forms of what? | [
"reproduction",
"photosynthesis",
"hibernation",
"absorption"
] | A | REVIEW QUESTIONS 4. Which form of reproduction is thought to be best in a stable environment? a. asexual b. sexual c. budding d. parthenogenesis 5. Which form of reproduction can result from damage to the original animal? a. asexual b. fragmentation c. budding d. parthenogenesis 6. Which form of reproduction is useful to an animal with little mobility that reproduces sexually? a. fission b. budding c. parthenogenesis d. hermaphroditism 7. Genetically unique individuals are produced through ________. |
SciQ | SciQ-3552 | thermodynamics
Title: Enthalpy change for exothermic and endothermic reactions I understood the concept behind endothermic and exothermic but finding it hard to understand it numerically.Let me describe my confusion through example.
Suppose for a reaction,
reactants require energy=$\rm40~J$
which on forming product give energy=$\rm50~J$ (so yes it is exomthermic)
where change in enthaply=$\rm10~J$
But as per the equation:
"Enthalpy change=Enthalpy of products- Enthalpy of reactants."
since enthalpy at constant pressure is Total heat content.
So I should have
Change in enthalpy=[U(internal energy)-50]-[U+40]=-90J
Could You explain it where I am getting this wrong? Is my understanding of enthalpy correct? According to the definition,
Enthalpy = Enthalpy(products) - Enthalpy(reactants), this should be followed.
When you are saying that 40 J are used up it means that 40 J are used in transforming the reactants to an activated complex(reaction intermediate) and when you say that 50J are released then it means that 50J is liberated when this activated complex is transformed to the product.
Assume that the energy of the activated complex be 0, then the energy of the reactant must be -40J(because 40J are required to convert reactant to the activated complex) , and the energy of the products should be -50J( because energy is released in converting the complex to the product)
Enthalpy(products)=-50J
Enthalpy(reactants)=-40J
Therefore,
Enthalpy = (-50)-(-40) J = -10J.
The following is multiple choice question (with options) to answer.
For an exothermic chemical reaction, energy is given off as reactants are converted to what? | [
"imports",
"forms",
"exports",
"products"
] | D | For an exothermic chemical reaction, energy is given off as reactants are converted to products. In chemical reactions where the products have a higher energy than the reactants, the reactants must absorb energy from their environment to react. These reactions are endothermic and can be represented by an energy-level diagram like the one shown in http://catalog. flatworldknowledge. com/bookhub/reader/2547 - gob-ch07_s04_f02. Figure 7.4 Endothermic Reactions. |
SciQ | SciQ-3553 | dna, mammals, eggs
Title: In what circumstances does a mammalian egg copy its DNA? In the 2nd episode of the new Cosmos series, the host Neil deGrasse Tyson shows how the white-furred bear could have evolved (reasonable scientific speculation, of course).
If you haven't seen that episode, here's the link. Great show, by the way.
So, it shows the bears eggs, and then goes on to show how there can happen an error in the DNA copying, that leads to the brown pigment production malfunction. Here's an excerpt from the subtitles text:
- great bears roamed the frozen wastes of Ireland.
- This might look like an ordinary bear,
- but something extraordinary is happening inside her.
- Something that will give rise to a new species.
- In order to see it, we'll need to descend down to a much smaller scale, to the cellular level, so that we can explore the bear's reproductive system.
..
- Those are some of her eggs.
- To see what's going on in one of them,
- we'll have to get even smaller.
- We'll have to shrink down to the molecular level.
..
- When a living cell divides in two,
- each one takes away with it a complete copy of the DNA.
- A specialized protein proofreads to make sure
- that only the right letters are accepted
- so that the DNA is accurately copied.
- But nobody's perfect.
- Occasionally, a proofreading error slips through,
- making a small, random change in the genetic instructions.
- A mutation has occurred in the bear's egg cell.
- A random event as tiny as this one can have consequences on a far grander scale.
- That mutation altered the gene that controls fur color.
- It will affect the production of dark pigment in the fur
- of the bear's offspring.
The following is multiple choice question (with options) to answer.
Which is the ultimate energy source in a bear's food chain? | [
"decomposers",
"plants",
"sun",
"heat"
] | C | Bears get their energy from their food. Brown bears eat a varied diet, from nuts and berries to fish and other animals. When bears eat a berry, they are obtaining energy that the plant originally captured from the sun. Even when a bear eats another animal, the energy in that animal ultimately came from eating a producer that captured the sun's energy. |
SciQ | SciQ-3554 | zoology, entomology
Title: How do insects know what is edible? What is the current scientific consensus on how insects innately know what is food and not food? If they are introduced to new food sources do they experiment with eating the new food? Could you teach a preying mantis to eat beef? Insect feeding behaviour is generally triggered by one or more conditions which may include colour, shape, chemical traces or temperature.
Insects generally locate food based on some combination of olfactory, thermal and visual queues (colour and shape). If their minimum criteria are met to specified tolerance, they will attempt to feed on whatever is nearby using their usual feeding method.
When these conditions appear on the 'wrong' target, it attracts insects and triggers feeding attempts. Insects can be triggered to feed on atypical food sources if the relevant aspects of their environment match those of their normal feeding environments. For example, here is a report from a professor of entomology recollecting his observations of being bitten by pea aphids while handling plants, which he assumes is because of the scent on his hands.
We can exploit this in various ways for research. One is for artificial blood-feeding of insects: most systems, like the Hemotek membrane feeding system, warm blood to the body temperature of the host. They do not normally resemble a target host in any other way. Some blood-feeding insects have very specific requirements for temperature (for example they will only feed on blood if it is heated to the body temperature of birds; the same blood heated to mammalian body temperature will be ignored) but we do not need to make the target look or smell like the natural host. Other species may need olfactory cues, which can be provided by researchers rubbing the membranes on their forearms before placing them on the feeding system, or by breathing on cages as you add the food.
A second way we exploit this is for insect traps. Although not all traps work this way, some work by mimicking the host and attracting insects that are looking for a meal. This can be via olfactory/chemical mimicry (for example carbon dioxide baited traps - try Googling "CO2-baited traps") or visual. Different degrees of visual 'deception' may be needed; for instance to attract tsetse flies, colour is important but shape is not:
The following is multiple choice question (with options) to answer.
Insect's antennae are useful for sensing what? | [
"sunlight",
"microorganisms",
"chemicals",
"contaminants"
] | C | Insects have six legs and a pair of antennae for sensing chemicals. They also have several eyes and specialized mouthparts for feeding. |
SciQ | SciQ-3555 | endocrinology, enzymes
Title: Renin - enzyme or hormone? Wikipedia says :
The kidneys secrete a variety of hormones, including erythropoietin,
and the enzyme renin.
Can a substance be both an enzyme and a hormone ? Why is renin both an enzyme and a hormone ? Yes, something can be both a hormone and an enzyme. There are a group of hormones known as peptide hormones. These are proteins (such as enzymes) that act as hormones indirectly (and maybe directly too?). A hormone is a chemical secreted by a cell that has some effect on another cell elsewhere in the body. In this case, the chemical just happens to be an enzyme. You can read about them on Wikipedia
Renin is secreted by the kidney, but its involved in arterial vasoconstriction (outside of kidney cells), so it is a hormone. And its also a peptide/enzyme, so it is considered both a hormone and an enzyme
The following is multiple choice question (with options) to answer.
"endocrine" and "exocrine" are two types of what? | [
"glands",
"organs",
"cells",
"fluids"
] | A | The ductless endocrine glands are not to be confused with the body’s exocrine system, whose glands release their secretions through ducts. Examples of exocrine glands include the sebaceous and sweat glands of the skin. As just noted, the pancreas also has an exocrine function: most of its cells secrete pancreatic juice through the pancreatic and accessory ducts to the lumen of the small intestine. |
SciQ | SciQ-3556 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
What is the term for the movement of molecules from an area of high concentration to an area of low concentration? | [
"passive transport",
"Osmosis",
"diffusion",
"concentration"
] | C | Diffusion is the movement of molecules from an area of high concentration to an area of low concentration. |
SciQ | SciQ-3557 | # New paper on genomics
James Lee and I have a new paper out: Lee and Chow, Conditions for the validity of SNP-based heritability estimation, Human Genetics, 2014. As I summarized earlier (e.g. see here and here), heritability is a measure of the proportion of the variance of some trait (like height or cholesterol levels) due to genetic factors. The classical way to estimate heritability is to regress standardized (mean zero, standard deviation one) phenotypes of close relatives against each other. In 2010, Jian Yang, Peter Visscher and colleagues developed a way to estimate heritability directly from the data obtained in Genome Wide Association Studies (GWAS), sometimes called GREML. Shashaank Vattikuti and I quickly adopted this method and computed the heritability of metabolic syndrome traits as well as the genetic correlations between the traits (link here). Unfortunately, our methods section has a lot of typos but the corrected Methods with the Matlab code can be found here. However, I was puzzled by the derivation of the method provided by the Yang et al. paper. This paper is our resolution. The technical details are below the fold.
# Paper on compressed sensing and genomics
New paper on the arXiv. The next step after the completion of the Human Genome Project, was the search for genes associated with diseases such as autism or diabetes. However, after spending hundreds of millions of dollars, we find that there are very few common variants of genes with large effects. This doesn’t mean that there aren’t genes with large effect. The growth hormone gene definitely has a large effect on height. It just means that variations of genes that are common among people have small effects on the phenotype. Given the results of Fisher, Wright, Haldane and colleagues, this was probably expected as the most likely scenario and recent results measuring narrow-sense heritability directly from genetic markers (e.g. see this) confirms this view.
The following is multiple choice question (with options) to answer.
What factors determine the effect of a gene? | [
"ribosomes",
"alleles",
"metabolites",
"genomes"
] | B | For example, remember that for the height gene in pea plants there are two possible factors. These factors are alleles. There is a dominant allele for tallness (T) and a recessive allele for shortness (t) . |
SciQ | SciQ-3558 | zoology, terminology, nomenclature, invertebrates, etymology
Urochorda
Cephalochorda
Craniata
which is more or less the accepted division today, with Urochorda being called Urochordata now.
In this essay, Lankester says:
The evidence of degeneration is admitted as conclusive in the case of the parasitic Crustacea and Cirrhipedes. It is equally incontestable in that very large and varied group of non-parasitic organisms, the Tunicata (Urochordate Vertebrata).2
(in the above 'Vertebrata' is what we call 'Chordata'). He adds this footnote:
2The whole argument as to the Tunicates of course rests on the view- supported by many arguments, that the larval urochord, which many of
them possess, is not a larval organ acquired by larval adaptation, but is hereditary and transmitted from adult ancestors.
The term 'urochord' seems to be established and used without comment there, and probably is taken as simple neo-Latin for 'tail chord', although that may be somewhat loose, perhaps meaning the notochord is present but does not extend into the head. A 1913 Webster's Dictionary defines urochord as:
(Zool.) The central axis or cord in the tail of larval ascidians and of certain adult tunicates.
In 1882, Lankester futher discussed the anatomy of the tunicates in the context of the division of the chordata in a paper called "The Vertebration of the Tail of Appendiculariæ". This paper includes an illustration of a larval tunicate with the "notochord (urochord)" indicated.
The following is multiple choice question (with options) to answer.
What type of craniates have backbones? | [
"vertebrates",
"juveniles",
"larva",
"invertebrates"
] | A | 34.3 Vertebrates are craniates that have a backbone. |
SciQ | SciQ-3559 | immunology, lab-techniques, flow-cytometry, cell-sorting
Without lysis, the RBCs overwhelm the cytometer, as they make up around 95% of the cells in human whole blood. White blood cells (leukocytes), on the other hand, only make up 0.1-0.2% of cells, and lymphocytes between about 15 to 50% of leukocytes.
The cell mixture is then analyzed on a cell sorter such as a BD FACSAria.
From: https://commons.wikimedia.org/wiki/File:Fluorescence_Assisted_Cell_Sorting_%28FACS%29_B.jpg
The cells pass in single file past one or more laser beams, which excite the dyes and cause them to fluoresce at a certain wavelength. The user can then use gating to select the combination and intensity of colors they are interested in, and when a cell meets the criteria, it is given an electrical charge, and electro magnets direct it into a collection container.
The following is multiple choice question (with options) to answer.
What are the most numerous blood cells? | [
"neutrophils",
"white blood cells",
"platelets",
"red blood cells"
] | D | |
SciQ | SciQ-3560 | 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.
How do autotrophs get food? | [
"From Plant matter",
"From Water",
"make their own",
"Soak up from host cell"
] | C | Autotrophs make their own food. Heterotrophs get food by eating other living things. |
SciQ | SciQ-3561 | neural-networks, machine-learning, deep-learning, training
Title: Training an AI to recognize my voice (or any voice) I want to start a project for my artificial intelligence class about speaker recognition. Basically, I want to train my AI to detect if it's me who's speaking or somebody else. I would like some suggestions or libraries to work with. The human voice is based on the neural muscular control of vocal apparatus made up of many parts.
Diaphragm
Vocal cords
Throat (constrictors and anti-constrictors)
Nasal cavity
Cheek
Jaw
Tongue
These coordinated muscular manipulations produce envelopes (controlling) of audio that can be characterized by periodic and transient wave forms.
Volume
Pitch
Tone (relative volume of harmonics)
Consonant transients
Voices are unique to the learning state of neural activity and anatomic attributes, which is a way of saying that vocal habits and the physical attributes of the voice supports the distinguishing of vocal identity.
Strength of vocal muscles
Connectivity of muscles to bone, tendons, and cartilage
Shape of inner surface of vocal pathways
Neural coordination of those muscles
Neural production of phonetic control to produce linguistic elements
Neural serialization of semantic structures (ideas)
The following is multiple choice question (with options) to answer.
In boys, what hormone stimulates the growth of the larynx and thickening and lengthening of the vocal folds, which causes the voice to drop in pitch during puberty? | [
"Endocrine",
"Petuitary",
"testosterone",
"Sexual"
] | C | years or more. During this time, a girl’s height can increase 3 inches a year. The next step in puberty is menarche, the start of menstruation. In boys, the growth of the testes is typically the first physical sign of the beginning of puberty, which is followed by growth and pigmentation of the scrotum and growth of the penis. The next step is the growth of hair, including armpit, pubic, chest, and facial hair. Testosterone stimulates the growth of the larynx and thickening and lengthening of the vocal folds, which causes the voice to drop in pitch. The first fertile ejaculations typically appear at approximately 15 years of age, but this age can vary widely across individual boys. Unlike the early growth spurt observed in females, the male growth spurt occurs toward the end of puberty, at approximately age 11 to 13, and a boy’s height can increase as much as 4 inches a year. In some males, pubertal development can continue through the early 20s. |
SciQ | SciQ-3562 | acid-base, ph
Title: When an acid is added to water, why does the hydroxide ion concentration decrease? At equilibrium in pure water, we have
$$\ce{[H_3O+][OH-]} = 10^{-14}$$
Since $\ce{H3O+}$ and $\ce{OH-}$ ions are produced in pairs, we may conclude
$$\ce{[H_3O+]}=\ce{[OH-]} = 10^{-7}$$
So far so good. But shouldn't things change when we introduce a new substance into water ? I mean why does the first equation above hold no matter what ?
Also when I introduce $\ce{H2SO4}$ into the water, it doesn't just give a $\ce{H+}$ ion, it also gives $\ce{HSO4-}$ ion. Shouldn't these new negative ions change the behavior of water? Why does my textbook never talk about these new negative ions? Help appreciated. Thanks! Your question title is a bit misleading, but i try to answer all the small questions in you question text.
The equation $[\ce{H3O^+}][\ce{OH^-}]$ holds true, if other parameters (like T) are constant. Keep in mind, the power of hydroxide decreases, whereas the power oxonium increases. Being equal in the equation and considering how logs are being computed,bthey will add up to 14 every time.
Regarding the introduced $\ce{HSO4^-}$, they don't contribute to pH by definition. On the other hand, they alter the behaviour of the water, by increasing its conductivity.
Your textbooks don't talk about the other negative ions in acidic or alkaline solutions, because they don't directly contribute to the values of pH or pOH by definition. In cases of polyacids like sulfuric acid, ions like $\ce{HSO4^-}$ are accounted for by using a different formula to calculate the actual pH value, but the "not-hydrogen" part is largely irrelevant in the behaviour of the solution itself.
The following is multiple choice question (with options) to answer.
What is an ionic compound that produces negative hydroxide ions when dissolved in water | [
"isomer",
"acid",
"catalyst",
"base"
] | D | A base is an ionic compound that produces negative hydroxide ions when dissolved in water. Bases taste bitter and turn red litmus paper blue. |
SciQ | SciQ-3563 | cell-division
Title: Why doesn't cellular, replicative senescence (or the hayflick limit) constrain the normal development of an organism? The wikipedia article on cellular senescence states:
Cellular senescence is the phenomenon by which normal diploid cells cease to divide. In culture, fibroblasts can reach a maximum of 50 cell divisions before becoming senescent. This phenomenon is known as "replicative senescence", or the Hayflick limit.
The following is multiple choice question (with options) to answer.
What is the name for the disease in which cells divide out of control? | [
"mutation",
"cancer",
"angina",
"diabetes"
] | B | Knowledge gained by this basic research on yeast cells has been applied to practical problems. Scientists have developed drugs to treat cancer based on knowledge of the cell cycle. Cancer is a disease in which cells divide out of control. The new drugs interfere with the cell cycle of cancer cells, so the cells stop dividing. This is an example of applied science. The aim of applied science is to find solutions to practical problems. Applied science generally rests on knowledge gained by basic science. |
SciQ | SciQ-3564 | physiology
Title: How does a nerve cell adjust if O2 diffusion is interrupted? What effects would it have on a nerve if the oxygen supply is cut off? Is there any data on this?
Does the nerve conductance velocity increase? What about the Amplitude and receptor-channels on/in the nerve?
Funnily enough it's insanely hard to come by an answer to this question, or maybe I'm just searching at the wrong places.... If Oxygen diffusion is interrupted, there is a serious problem. Neurons inside of the brain slowly start to die, many other things like change in personality or the inability to process pain impulses occur if the brain is deprived of oxygen.If this is not fixed within 15 minutes it is impossible to survive.
The actual effects on the neurons are as follows:
Like in most cells the first solution to this kind of circumstance is anaerobic metabolism, the same happens in neurons but it does not last long and it is inefficient. As far as i'm concerned nerve conductance decreases in this kind of scenario and the receptors shrivel.
Well if the receptors are shriveling, they shouldn't be able to transfer impulses meaning that nerve conductance should stop.
This link to an article on the effects on the brain from oxygen deprivation.
https://www.livestrong.com/article/106179-effects-lack-oxygen-brain/
The following is multiple choice question (with options) to answer.
The period immediately following the transmission of an impulse in a nerve or muscle, in which a neuron or muscle cell regains its ability to transmit another impulse, is called the ______ period. | [
"activation",
"refractory",
"interstitial",
"extraction"
] | B | The deadly nerve gas Sarin irreversibly inhibits acetycholinesterase. What effect would Sarin have on muscle contraction? After depolarization, the membrane returns to its resting state. This is called repolarization, during which voltagegated sodium channels close. Potassium channels continue at 90% conductance. Because the plasma membrane sodium–potassium ATPase always transports ions, the resting state (negatively charged inside relative to the outside) is restored. The period immediately following the transmission of an impulse in a nerve or muscle, in which a neuron or muscle cell regains its ability to transmit another impulse, is called the refractory period. During the refractory period, the membrane cannot generate another action potential. The refractory period allows the voltage-sensitive ion channels to return to their resting configurations. The sodium potassium ATPase continually moves Na+ back out of the cell and K+ back into the cell, and the K+ leaks out leaving negative charge behind. Very quickly, the membrane repolarizes, so that it can again be depolarized. |
SciQ | SciQ-3565 | magnetic-fields, neutron-stars, superfluidity, pulsars
Title: Do neutron stars emit stellar flares? Since stellar flares are formed from the magnetic energy of a star, is it probable to assume that neutron stars can emit stellar flares as well? If so, how would the super fluid material of the star behave? Would there be anyway to observe such phenomena? There are classes of neutron star called soft gamma ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs), which emit bursts of high energy radiation that last (usually) from less than a second to maybe 100s.
It is thought that these objects have extremely strong fields of up to $10^{11}$ T, which is produced during a core collapse supernova when some sort of dynamo action augments the usual field amplification by flux conservation.
These "magnetars" are thought to have a strong magnetic field that powers the high energy radiation. Magnetic energy may be stored in the interior of the neutron star or in the magnetosphere by twisting the field into configurations with a lot of potential energy. This is then stochastically released as the field relaxes again, producing "flares". See for example Link (2014).
To some extent this process is a little bit like the magnetically powered flares on stars, but unlike stars, where the field is regenerated by an internal dynamo, it is thought that magnetar magnetic fields decay on timescales of 10,000 years.
The following is multiple choice question (with options) to answer.
What kinds of neutron stars emit radiation in pulses? | [
"quasars",
"dwarf stars",
"pulsars",
"red giants"
] | C | A pulsar is a rotating neutron star that emits radiation in pulses. A pulsar can only be seen when the beam is pointing toward Earth. Pictured below is a nebular that looks like a cosmic hand ( Figure below ). There is a bright swirl of gas in the wrist of the hand. A very tiny but bright neutron star is in the center of that swirl. |
SciQ | SciQ-3566 | machine-learning, reinforcement-learning, q-learning, experience-replay
Also, it is likely that following a policy which is derived from $Q_t$ would lead to $a_{t}$, whereas following a policy which is derived from $Q_{t+x}$ would not.
Yes that is correct. However, you don't care about that for a single step, you just care about calculating a better estimate for $Q(s,a)$ regardless of whether you would choose $a$ in state $s$ with the current policy. That is what an action value measures - the utility of taking action $a$ in state $s$ and thereafter following a given policy.
This is a strength of experience replay, that you are constantly refining your estimates of off-policy action values to determine which is the best.
This does become more of an issue when you want to use longer trajectories in the update step (which you may want to do to reduce bias of your TD target estimate). A series of steps in history $s_t,a_t,r_t ... s_{t+1}, a_{t+1},r_{t+1}...s_{t+n}$ may not have the same chance of occurring under the latest policy as it did when it was stored in memory. For the first step $s_t,a_t$ again you don't care if it is one you would currently take because the point is to refine your estimate of that action value. However, if you want to use $r_{t+1}, r_{t+2}$ etc plus $s_{t+n}$ to create a TD target, then you have to care whether your current policy and the one used to populate the history table would be different.
It is a problem if you want to use more sophisticated estimates of TD target that use multiple sample steps along with experience replay. There are some approaches you can take to allow for this, such as importance sampling. For a single step update mechanism you don't need to worry about it.
I don't see in the experience replay algorithm that the Q value $Q_t(s_t, a_t)$ is saved, so I must assume that is is not.
The following is multiple choice question (with options) to answer.
What is the change in behavior based on experience? | [
"applying",
"observing",
"learning",
"analyzing"
] | C | |
SciQ | SciQ-3567 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
Competition with what emerging animal group may have led to extinction of cynodonts about 200 million years ago? | [
"insects",
"amphibians",
"mammals",
"reptiles"
] | C | Cynodonts probably gave rise to mammals about 200 million years ago. However, they are not considered to be mammals themselves. In fact, competition with early mammals may have led to their extinction. They went extinct sometime during the Jurassic or Cretaceous Period. |
SciQ | SciQ-3568 | physical-chemistry, bond, water, atoms, molecules
Title: Why does matter have spaces between them? If you mix sugar Crystal in a glass of water and mix it well, the level of water will not rise.The reason they say is that matter have spaces between them.If matter have spaces between them , How come that empty space is not visible to our eyes.If I look at a glass of water , I see all the molecules mixed up well.Not like there are some areas where there is no H20 molecule and some they’re are.
What does it exactly mean and how does it look like and what is happening there?
My thinking:
Is it like there are intermolecular forces between H20 molecules but they are at a separation from each other and still have the bond.Why does level inc if I put my finger. Note that there is the law of mass and energy conservation, but there is no law about volume conservation.
Molecules of matter are in eternal motion. Molecules of gases move freely by flying between collisions. Nitrogen or oxygen molecules of air have an average speed of a supersonic fighter, colliding at rate typically 10 billions collisions per second, with the mean free flight distance typically 70 nm. Such motion creates space between them. ( Try to keep a sworm of vivid children in tight packed formation. )
Molecules of liquids and solids are held together by attractive forces. Loosely for the former, so they continuously separate and rejoin. Tightly for the latter, so they just vibrate.
Another reason for space between molecules is electrostatic repulsion of their electrons, if they get too close. If you hit a wall, you did not really touch it. The wall started to repulse you by the mighty electrostatic force, when your and it's electrons got too close.
If you mix 1 L of ethanol and 1 L of water and let it cool down ( because it warms up ), the total volume will not be 2 L, but about 1.96 L. It is due the fact the average energy of bonds water-ethanol (via hydrogen bonds) is greater than the average energy of bonds water-water and ethanol-ethanol. This leads to shorter average distance between molecules ( fractions of nanometre ), as stronger bonds are shorter, and to the volume contraction.
The following is multiple choice question (with options) to answer.
Within a bud, what is spaced close together because the internodes are very short? | [
"roots",
"stems",
"leaves",
"chordae"
] | C | |
SciQ | SciQ-3569 | muscles, lungs, human-physiology
Title: Why is there smooth muscle in our bronchioles? Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just remain open? There are at least two things to consider.
First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good enough source of that)
Secondly, you are incorrect in assuming that normal state is "dilated". Dilation of branchioles is sympathetic ("fight-and-fly") response of the nervous system to something like danger, that requires short-term boost in energy production. That is, by default, your airflow is limited. Probably, to limit amount of energy you effectively burn via oxygenation. But most importantly, you leave yourself a reserve in terms of oxygen supply for critical moments.
Some more information you might find here.
The following is multiple choice question (with options) to answer.
What controls the opening to the airway and gut? | [
"teeth",
"tongue",
"mandible",
"electrons"
] | C | Although it is not found in the skull, the hyoid bone is considered a component of the axial skeleton. The hyoid bone lies below the mandible in the front of the neck. It acts as a movable base for the tongue and is connected to muscles of the jaw, larynx, and tongue. The mandible articulates with the base of the skull. The mandible controls the opening to the airway and gut. In animals with teeth, the mandible brings the surfaces of the teeth in contact with the maxillary teeth. The Vertebral Column The vertebral column, or spinal column, surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and muscles of the back and neck. The adult vertebral column comprises 26 bones: the 24 vertebrae, the sacrum, and the coccyx bones. In the adult, the sacrum is typically composed of five vertebrae that fuse into one. The coccyx is typically 3–4 vertebrae that fuse into one. Around the age of 70, the sacrum and the coccyx may fuse together. We begin life with approximately 33 vertebrae, but as we grow, several vertebrae fuse together. The adult vertebrae are further divided into the 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar vertebrae (Figure 38.8). |
SciQ | SciQ-3570 | mass, density, volume
Title: Confused about volume, density and mass, help! I got into an argument with my friend, which cast confusion on my understanding of density and its relationship to volume. I'm hoping to get some clarity. The argument involved describing density in terms of volume. Let's say you define a sphere in empty space. You choose a point, apply the formula for a sphere, and now you have a sphere. Not a sphere OF anything other than space, just a spacial, theoretical sphere. No particles, massless or otherwise (this is a thought experiment). What is the density of that sphere? Is it zero, or is it undefined? I know density can be defined as p = m/v. But in a theoretical sphere, which HAS volume, should we call mass zero, because there is none? Or is it undefined because a theoretical sphere really isn't related to mass at all? If it IS undefined, does that mean it makes no sense to relate density to volume because density is only a property of mass?
The answer, to me, seems to be that in fact it makes no sense to talk about the density of a massless object. Sorry if I answered my own question, but I would still like clarity. If someone could help guide me through the assumptions I'm making about reality and math and how they relate, I'd really appreciate it. Theoretically speaking, in order for something (usually particles) to be massless, it has to be travelling in the speed of light. In quantum theory, uncertainty principle states that the position and momentum of such particle cannot be accurately determined, therefore it is not possible to measure the volume of the particle. So it is generally assumed that the volume is too small and/or insignificant.
Regarding your question, I think that the simple answer would be; a massless object would have no volume nor density, or immeasurable. Take your pick.
The following is multiple choice question (with options) to answer.
When there is no mass in a volume of space, the space is not what? | [
"curved",
"straight",
"timed",
"flat"
] | A | When there is no mass in a volume of space, the space is not curved. An object passing through such space would follow a straight line in our normal way of thinking of a straight line. |
SciQ | SciQ-3571 | sensation, olfaction
http://www.comeaddestrareuncane.com/blog/tag/cani-molecolari/
In the dog, the surface of the olfactory mucosa varies between 70 and 150 cm2 - in this tissue the number of olfactory receptors varies from 250 to 280 million - In 1962, Becker et al. showed that dogs are able to recognize substances in dilutions from 1/100 to 1/10.000.000.
- http://milano.corriere.it/milano/notizie/cronaca/12_febbraio_19/cani-olfatto-parere-esperto-1903358352720.shtml
Have you noticed how a dog sniffs the urine of a female "tasting it"? It is the same action that makes the viper when it follows the track of the mouse: it evertes the tongue and carries on it the odorous particles in the buccal cavity, and this organ has a function in the middle between the olfactory and gustatory ones. "Pointing dogs" is as pointing "the wild" taste the smell.
"Eat the scent", in the jargon, because savored, not only in terms of smell, the smell of the wild. The Jacobson's organ is then a second organ capable of perceiving odors, the first we've said is represented ciliated epithelium of the mucous membrane of the nose.
But there is a third organ called the "Rodolfo-Masera" which also serves to sense the emanations chemical (not yet known which), that way you could explain a specialization of these organs to perceive certain groups of biochemicals than others.
- http://www.laciotola.net/Cani/la-funzione-olfattiva-del-cane.html
The following is multiple choice question (with options) to answer.
Cells selective for different odorants are interspersed in what anatomical cavity? | [
"mucus",
"facial",
"nasal",
"abdominal"
] | C | |
SciQ | SciQ-3572 | evolution, natural-selection
In fact since civilization has started feeding the hungry, making the hunting of wild beasts less important, causing the shrinkage of the male physique (we used to be much more muscular), inventing medicine and schools where smarts can be selected for, and giving us all more choice when it comes to mates, evolution has accelerated for human beings. The authors specifically cite social factors as being more important in our evolution now.
The following is multiple choice question (with options) to answer.
What has revolutionized human society over the past several decades? | [
"food technology",
"computer technology",
"flight technology",
"travel technology"
] | B | Over the past several decades, computer technology has revolutionized human society. Watch this video interview about ways computers have changed people’s lives. Then answer the questions below. |
SciQ | SciQ-3573 | particle-physics, elements
Title: Is it possible to create a new element that doesn't exist in the universe? When I say something new I do not refer to something already made like H,O etc and when I mean something new I do not refer to a transformation like tritium to helium and gold.
If so how ?(I mean is there a specific way to do that ?) Yes, so far, 20 synthetic elements have been created, with atomic numbers 99 (Einsteinium) to 118 (Ununoctium). All these elements are unstable, with half-lives ranging from a year to a few milliseconds.
You can find a list on wikipedia. These elements are produced in specialized nuclear reactors, by bombarding heavy elements like Uranium and Plutonium with neutrons or other elements.
The following is multiple choice question (with options) to answer.
What do you call the set of seventeen chemical elements possessing particular importance for a variety of industrial processes, used frequently in modern technology? | [
"base chemicals",
"reactive elements",
"rare earth metals",
"fossil fuel"
] | C | The rare earth metals are a set of seventeen chemical elements (the lanthanide series plus scandium and yttrium) that have particular importance for a variety of industrial processes and are used frequently in modern technology. Despite their name, rare earth metals are actually relatively abundant in the earth’s crust. However, the extraction of many of these metals is quite difficult and has made their supply somewhat limited. They are highly sought after for this reason. Figure below shows the rare earth metals. |
SciQ | SciQ-3574 | brain, terminology, neuroanatomy, etymology
anterior to or involving the anterior part of a frontal structure
Anterior meaning
situated before or toward the front
Indeed Siddiqui et al (2008) mention:
The anterior part of the frontal lobe referred in the literature as ‘pre’-frontal lobe has been simultaneously referred to as ‘frontal granular cortex’ and ‘frontal association cortex.’ The anterior most portion of the frontal lobe is occupied by the PFC...
Reference
- Siddiqui et al., Indian J Psychiatry (2008); 50(3): 202–8
Fig. 1. The frontal lobe includes the prefrontal cortex (PFC). source: Socratic
The following is multiple choice question (with options) to answer.
Broca’s area, responsible for the production of language or controlling movements responsible for speech, is nearly always located on what side of the brain? | [
"half",
"Hand",
"back",
"left"
] | D | are responsible for establishing long-term memory, but the ultimate location of those memories is usually in the region in which the sensory perception was processed. The main sensation associated with the parietal lobe is somatosensation, meaning the general sensations associated with the body. Posterior to the central sulcus is the postcentral gyrus, the primary somatosensory cortex, which is identified as Brodmann’s areas 1, 2, and 3. All of the tactile senses are processed in this area, including touch, pressure, tickle, pain, itch, and vibration, as well as more general senses of the body such as proprioception and kinesthesia, which are the senses of body position and movement, respectively. Anterior to the central sulcus is the frontal lobe, which is primarily associated with motor functions. The precentral gyrus is the primary motor cortex. Cells from this region of the cerebral cortex are the upper motor neurons that instruct cells in the spinal cord to move skeletal muscles. Anterior to this region are a few areas that are associated with planned movements. The premotor area is responsible for thinking of a movement to be made. The frontal eye fields are important in eliciting eye movements and in attending to visual stimuli. Broca’s area is responsible for the production of language, or controlling movements responsible for speech; in the vast majority of people, it is located only on the left side. Anterior to these regions is the prefrontal lobe, which serves cognitive functions that can be the basis of personality, short-term memory, and consciousness. The prefrontal lobotomy is an outdated mode of treatment for personality disorders (psychiatric conditions) that profoundly affected the personality of the patient. |
SciQ | SciQ-3575 | genetics
Additional response added as requested:
I see what you are getting at - why do children seem like such individual and unique things sometimes?
In sexual reproduction, the offspring are the product of the shuffling of the parent's genomes through meiosis, where the pairs of chromosomes we have are combined to make a single chromosome that will be half of the children genome.
This process can result in completely novel combinations of genes while conveying many likenesses from the parent. I would guesstimate that this is the major cause of the uniqueness of offspring/children.
Also in mammals there are some cell lines which splice families of genes which will cause offspring to be potentially quite different from either parent. Immune genes for instance are created from scratch from a bunch of genes that the parents give. Making each offspring unique but also the product of the parent's genetic repertoire. This can be significant as it affects health and also to some extent attraction - studies have shown that people who smell attractive to us are immunologically distinct from us.
@David mentions epigenetic variation, which is a more recent significant development. During our life, the germline (sperm/egg) DNA may be chemically labelled depending upon environmental conditions we experience. A famous example is experiencing famine conditions, which caused the children to be born on the small side amongst other effects. More recent studies have shown that this is a widespread mechanism to control cells in our body during our lifetime as well as communicate to our offspring how life is. It is expected that this labeling does not affect us forever - the epigenetic labels change over the course of a generation quite often (we believe).
The following is multiple choice question (with options) to answer.
Which theory is the idea that the characteristics of living organisms are controlled by genes, which are passed from parents to their offspring? | [
"evolution theory",
"gene theory",
"species theory",
"fossil theory"
] | B | The gene theory is the idea that the characteristics of living organisms are controlled by genes, which are passed from parents to their offspring. A gene is a segment of DNA that has the instructions to encode a protein. Genes are located on larger structures, called chromosomes , that are found inside every cell. Chromosomes, in turn, contain large molecules known as DNA (deoxyribonucleic acid). Molecules of DNA are encoded with instructions that tell cells what to do. To see how this happens, click on the animation titled Journey into DNA at the following link: http://www. pbs. org/wgbh/nova/genome/dna. html . |
SciQ | SciQ-3576 | zoology, terminology, nomenclature, invertebrates, etymology
Urochorda
Cephalochorda
Craniata
which is more or less the accepted division today, with Urochorda being called Urochordata now.
In this essay, Lankester says:
The evidence of degeneration is admitted as conclusive in the case of the parasitic Crustacea and Cirrhipedes. It is equally incontestable in that very large and varied group of non-parasitic organisms, the Tunicata (Urochordate Vertebrata).2
(in the above 'Vertebrata' is what we call 'Chordata'). He adds this footnote:
2The whole argument as to the Tunicates of course rests on the view- supported by many arguments, that the larval urochord, which many of
them possess, is not a larval organ acquired by larval adaptation, but is hereditary and transmitted from adult ancestors.
The term 'urochord' seems to be established and used without comment there, and probably is taken as simple neo-Latin for 'tail chord', although that may be somewhat loose, perhaps meaning the notochord is present but does not extend into the head. A 1913 Webster's Dictionary defines urochord as:
(Zool.) The central axis or cord in the tail of larval ascidians and of certain adult tunicates.
In 1882, Lankester futher discussed the anatomy of the tunicates in the context of the division of the chordata in a paper called "The Vertebration of the Tail of Appendiculariæ". This paper includes an illustration of a larval tunicate with the "notochord (urochord)" indicated.
The following is multiple choice question (with options) to answer.
Phylum chordata consists of two subphyla of invertebrates, as well as the hagfishes and what else? | [
"lipids",
"vertebrates",
"organs",
"cells"
] | B | |
SciQ | SciQ-3577 | inorganic-chemistry
Title: Do nitrogen and oxygen react to form nitric oxide or nitrous oxide? Various sources claim different products for the reaction between nitrogen and oxygen:
$$
\begin{align}
\ce{N2 + O2 &-> 2 NO} \tag{R1} \\
\ce{2 N2 + O2 &-> 2 N2O} \tag{R2}
\end{align}
$$
Which nitrogen oxide is actually formed? Are nitric and nitrous oxides formed in variable amounts, but depending on certain reaction conditions one is produced predominantly? Oxygen and nitrogen react to form nitric oxide. Following is from Wikipedia:
The uncatalyzed endothermic reaction of oxygen ($\ce{O2}$) and nitrogen ($\ce{N2}$), which is effected at high temperature ($\pu{>2000 °C}$) by lightning has not been developed into a practical commercial synthesis (see Birkeland–Eyde process):
$$\ce{N2 + O2 -> 2 NO}$$
The following is multiple choice question (with options) to answer.
What forms when nitrogen and oxygen combine at high temperatures? | [
"oxygen oxide",
"carbon dioxide",
"nitrogen oxide",
"ammonia oxide"
] | C | Nitrogen oxides form when nitrogen and oxygen combine at high temperatures. This occurs in hot exhausts from vehicles, factories, and power plants. |
SciQ | SciQ-3578 | structural-variation
Title: What is the exact definition of "breakend"? I'm reading the Manta User Guide
→ it is a method to discover structural variants and indels from next generation sequencing data.
The word 'breakend' is used in several contexts
I have searched for a definition in duckduckgo, qwant and google but have not found a concise definition.
Thanks for you help A structural variant is an inversion, deletion, duplication, or translocation. A "breakend" is one endpoint of a structural variant. This paper (Alkan et al. Nature Review Genetics 2011) may help you understand: https://www.nature.com/articles/nrg2958
The Manta paper and documentation seem sparse on diagrams. DELLY, another structural variant caller, has diagrams in their publication. Their paper may be more of use: https://academic.oup.com/bioinformatics/article/28/18/i333/245403
Specific example: Say you're sequencing a chronic myeloid leukemia (CML) tumor. You will likely find reads that half map to the ABL1 gene on chr9 and half map to the BCR gene on chr22 (https://en.wikipedia.org/wiki/Philadelphia_chromosome). The genomic position of the location where chr9 turns to chr22 is called the breakpoint. The positions on chr9 and chr22 are the breakends.
The following is multiple choice question (with options) to answer.
The posterior end of a typical rib is called what? | [
"bottom",
"head",
"chest",
"neck"
] | B | Parts of a Typical Rib The posterior end of a typical rib is called the head of the rib (see Figure 7.27). This region articulates primarily with the costal facet located on the body of the same numbered thoracic vertebra and to a lesser degree, with the costal facet located on the body of the next higher vertebra. Lateral to the head is the narrowed neck of the rib. A small bump on the posterior rib surface is the tubercle of the rib, which articulates with the facet located on the transverse process of the same numbered vertebra. The remainder of the rib is the body of the rib (shaft). Just lateral to the tubercle is the angle of the rib, the point at which the rib has its greatest degree of curvature. The angles of the ribs form the most posterior extent of the thoracic cage. In the anatomical position, the angles align with the medial border of the scapula. A shallow costal groove for the passage of blood vessels and a nerve is found along the inferior margin of each rib. |
SciQ | SciQ-3579 | human-biology, food, lungs
Title: What happens to the food you accidentally aspire? I'm well aware of the health effects of aspirating solid food and liquids, but I'm interested in the reaction of the body on the biological level to the strange body on our lungs.
After I almost aspirated corn, I started to wander: what does the body do when food got on our lungs?
Will it be eventually absorbed? Destroyed by our white cells? Or just lie there forever until it fully decomposes?
The body has mechanisms to prevent food to get into the lungs, so the body is aware that eventually some food will get into the lungs. As a result, it makes sense to believe that our body would have a mechanism to deal with such issue if all other mechanisms fail ( coughing and etc.,) yet I couldn't find anything on Google. People can drown because of aspired food. If they don't then it can cause diseases, for example pneumonia. In extreme cases a tree can grow in the lungs. There are other aspiration/inhalation related diseases like silicosis or asbestos lung cancer. So it depends on the composition of the object (or liquid or powder) and other factors whether it causes a disease or not. I did not find anything about what exactly happens with these objects in the lungs. Probably the lung tries to get rid of them mechanically, if there is no success in that, then they cause a local inflammation, which can lead to diseases if it becomes chronic and/or the object contains pathogens.
Common presenting symptoms (information available in 36 cases)
included dyspnea (14), fever (9), and cough (6). A history of
recurrent pneumonia was present in 9.
2007 - Pulmonary Disease due to Aspiration of Food and Other Particulate Matter: A Clinicopathologic Study of 59 Cases Diagnosed on Biopsy or Resection Specimens
The annual overall inpatient cost associated with pediatric bronchial
foreign-body aspiration is approximately $12.8 million. Combined, the
rate of death or anoxic brain injury associated with pediatric foreign
body is approximately 4%.
2014 - The national cost burden of bronchial foreign body aspiration in children
The following is multiple choice question (with options) to answer.
What is the name of the process in which solid food waste is passed out of the body? | [
"evaporation",
"extinction",
"regurgitation",
"elimination"
] | D | Some substances in food cannot be broken down into nutrients. They remain behind in the digestive system after the nutrients are absorbed. Any substances in food that cannot be digested and absorbed pass out of the body as solid waste. The process of passing solid food waste out of the body is called elimination. |
SciQ | SciQ-3580 | human-biology, cell-biology
Title: What kinds of cells does human saliva contain? I have heard that our saliva contains cells. What cell types can be found in human saliva? It contains white blood cells (leukocytes) and cells from the inner lining of the mouth (buccal epithelial cells). The DNA obtained from these cells is the basis of DNA profiling based on saliva samples.
Source: Salimetrics
The following is multiple choice question (with options) to answer.
The epidermis consists mainly of what type of cells? | [
"cytoplasm",
"blood cells",
"crystalline",
"epithelial"
] | D | Cell Layers of the Epidermis. The epidermis consists mainly of epithelial cells. |
SciQ | SciQ-3581 | cell-biology, fluorescent-microscopy, cytoskeleton
Other images for a more wholesome appreciation of the cytoskeleton.
Here follow a few micrographs of HeLa cells.
In green, actin.
In red, intermediate filaments stained with vimentin:
And now here you can see a microtubule stain in HeLa cells, in pink. Notice that some microtubules do actually make it around and across the nucleus.
The following is multiple choice question (with options) to answer.
What is the microtubule-organizing center found near the nuclei of animal cells? | [
"lysosome",
"entrosome",
"centrosome",
"spliceosome"
] | C | Animal Cells versus Plant Cells At this point, you know that each eukaryotic cell has a plasma membrane, cytoplasm, a nucleus, ribosomes, mitochondria, peroxisomes, and in some, vacuoles, but there are some striking differences between animal and plant cells. While both animal and plant cells have microtubule organizing centers (MTOCs), animal cells also have centrioles associated with the MTOC: a complex called the centrosome. Animal cells each have a centrosome and lysosomes, whereas plant cells do not. Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not. The Centrosome The centrosome is a microtubule-organizing center found near the nuclei of animal cells. It contains a pair of centrioles, two structures that lie perpendicular to each other ( Figure 4.15). Each centriole is a cylinder of nine triplets of microtubules. |
SciQ | SciQ-3582 | human-biology, biochemistry, metabolism, food
Absorption in the gut is different for glucose and fructose, as is transport into cells.
Both glucose and fructose are (or can be) metabolised to pyruvate. However fructose is first metabolised to fructose 1-phosphate, and only enters glycolysis at the triose phosphate stage. A consequence of this is that it by-passes any regulation that occurs for the metabolism of glucose after conversion to glucose 6-phosphate. (In addition, glucose 6-phosphate has alternative metabolic possibilities not shown).
Postscript
This provides the framework for considerations of the consequences of dietary intake of sucrose, which are not part of the question and off-topic here, as already mentioned. Despite that, this topic has been addressed in questions in SE Biology, as well as elsewhere on the internet. I try not to offer advice to others (nor to take it from strangers). However my wife, whose advice I am sometimes obliged to take, professes the following:
“All things in moderation, and moderation in all things.”
The following is multiple choice question (with options) to answer.
Glucose and fructose are considered this type of sugar? | [
"alcohols",
"monosaccharides, or simple",
"polysaccharides",
"complex carbohydrates"
] | B | Glucose and fructose are monosaccharides, or simple sugars. |
SciQ | SciQ-3583 | Emeritus
PF Gold
P: 5,196
Quote by I like Serena Hi cepheid! Trying to keep track in dealing with unordered stuff usually gives me a head ache. What I have learned to do, is first count the ordered stuff, and then divide by the number of duplicate countings. In your case you can order the objects in ##n!## ways, yielding ##m## ordered pairs. However, since the pairs are supposed to be unordered, we are counting each pair twice. So we need to divide by ##2^m##. Furthermore, the m pairs can be ordered in m! ways, so we need to divide by ##m!## to eliminate the duplicate countings. I believe the general formula is: $$N_{pairings}={n! \over m! 2^m}$$ I didn't try to brute force count and verify though... To illustrate with n=6, the first ordering is: (1,2),(3,4),(5,6) However, (2,1),(3,4),(5,6) is the same pairing which we would be counting separately. We need to divide by 2 for each pair in the pairing. That is, by 23. Furthermore, (3,4),(1,2),(5,6) is again the same pairing which we would also be counting separately. We need to divide by 3! to compensate.
The following is multiple choice question (with options) to answer.
How many orders can flying birds be divided into? | [
"29",
"44",
"19",
"31"
] | A | Flying birds are divided into 29 orders. The most common orders include landfowl, waterfowl, shorebirds, diurnal and nocturnal raptors, parrots, and perching birds. |
SciQ | SciQ-3584 | optics, waves, electric-fields, interference, diffraction
Title: Does constructive interference automatically imply bright fringes at all times? Suppose two waves interfere constructively at some point, in a double slit experiment set-up. This essentially means that the two waves have their peaks and troughs in sync with each other, and there is a phase difference of $2n\pi$. However, it is said that, we obtain bright fringes where waves interfere constructively.
However, this seems to be somewhat of an approximation to me. At constructive interference, if a wave has a peak at some point on the screen, the other wave would also have a peak. Similarly, if one wave has a trough, then the other wave also has a trough. However, how can we be sure that the first wave would definitely have a peak or a trough at that point ? Why not any other point in between ?
As the wave is moving forward, we can think of the screen as some point $x_0$ along the direction in which the wave moves. As the wave moves forward, the point $x_0$ on the wave, can be the peak, trough or any other point depending on time. So, the amplitude at any point on the screen oscillates too.
Since the displacement of the field at the screen oscillate, shouldn't we get an oscillating or 'flickering' intensity fringe pattern, instead of a constant bright-dark pattern ? Shouldn't the bright regions flicker extremely fast ?
Will this be true, even in case of double slit diffraction ? A detector, such as your eye, does not respond at the rate of oscillation of the optical or RF frequency, instead it responds to the variation of its peaks or to variation of its average power (energy per cycle). These variations are many orders of magnitude slower than the oscillation rate. For example your eyes can tell the difference of brightness but only at the rate of few hundred hertz. In an ideal double-slit experiment the nulls are completely zero non-oscillating in intensity, there really is no energy; at the intensity peaks those do fluctuate at the rate of the oscillation (optical or RF) frequency but the detector ignores that and responds to the peaks or rms energy.
The following is multiple choice question (with options) to answer.
Two types of interference found in waves are constructive and what else? | [
"destructive",
"primitive",
"conductive",
"osmotic"
] | A | Discussion The intensity goes up by a factor of 4 when the amplitude doubles. This answer is a little disquieting. The two individual waves each have intensities of 1.00 W/m 2 , yet their sum has an intensity of 4.00 W/m 2 , which may appear to violate conservation of energy. This violation, of course, cannot happen. What does happen is intriguing. The area over which the intensity is 4.00 W/m 2 is much less than the area covered by the two waves before they interfered. There are other areas where the intensity is zero. The addition of waves is not as simple as our first look in Superposition and Interference suggested. We actually get a pattern of both constructive interference and destructive interference whenever two waves are added. For example, if we have two stereo speakers putting out 1.00 W/m 2 each, there will be places in the room where the intensity is 4.00 W/m 2 , other places where the intensity is zero, and others in between. Figure 16.45 shows what this interference might look like. We will pursue interference patterns elsewhere in this text. |
SciQ | SciQ-3585 | homework, reproduction, embryology
Title: Which process is needed to complete male reproductive development? In order to properly complete male reproductive development:
A. primordial germ cells must begin Meiosis I in utero.
B. Sertoli cells must produce testosterone.
C. Dihydrotestosterone must masculinize Wolffian duct derivatives
D. the paramesonephric ducts must degenerate
E. the metanephros must form the genital epithelium
My attempt: I think the answer is C because testosterone turns into DHT which then masculinzing the wolffian duct. Other people I am studying with claim the answer is D (which is true) except that I dont think the loss of the paramesonephric duct is needed to complete male repro development. Regarding option C:
Although it is correct that testosterone is converted into DHT, it is the former, not the latter, which is responsible for differentiation of the mesonephric (a.k.a. Wolffian) ducts:
Between 8 and 12 weeks, the initial secretion of testosterone stimulates mesonephric ducts to transform into a system of organs—the epididymis, vas deferens, and seminal vesicle—that connect the testes with the urethra.*
DHT (dihydrotestosterone) is produced in the Leydig cells by the 5α-Reductase enzyme. It is required for induction of the external male genitalia (urethra, penis, and scrotum) and prostate from the embryonic ureteral groove, and for testicular descent into scrotum.
Regarding option D:
Sertoli cells secrete Anti Müllerian Hormone (AMH), which causes degeneration of the müllerian (a.k.a. paramesonephric) ducts between weeks 8 and 10. It is normal to speak about degeneration of the müllerian ducts as a defining aspect of male embryology, and thus I believe answer D is correct. Your point is taken, however:
Nevertheless, small müllerian duct remnants can be detected in the adult male, including a small cap of tissue associated with the testis, called the appendix testis, and an expansion of the prostatic urethra, called the prostatic utricle.*
The following is multiple choice question (with options) to answer.
What is the name of the tube that carries sperm from the epididymis to the urethra? | [
"prostate gland",
"fallopian tube",
"vas deferens",
"ureter"
] | C | The vas deferens is a tube that carries sperm from the epididymis to the urethra. |
SciQ | SciQ-3586 | population-dynamics, population-biology
Title: Spread of a benign virus in a population over time This is a somewhat difficult (for me) population dynamics question and I wonder if someone with experience in this area could suggest a reasonable approach?
My simplifying assumptions: As a gross oversimplification, let p(k) be the world's population at generation k, and assume a smooth exponential curve that models p(k) from $k=0$ at 10,0000 B.C.E to generation $k=600$ in 2000 C.E. A generation is 20 years, and in acc. with this Wiki there are about 4 million individuals at $k=0$ and 6070 million at $k=600.$
(Of course the exponential model is bad, as world population growth appears to have been sluggish before recorded history.)
Now assume a benign virus infects 120 individuals in $k=0.$ It benignly infects all individuals who have at least one infected parent. Perhaps unimportantly, it also continues to infect 30 new individuals per million in each generation (because its found in the soil), but would not infect those already exposed.
Call infected individuals II and non-infected NI. They are indistinguishable without clinical tests--which are not done, since the virus is harmless. Since II individuals are almost certain to mate with NI individuals, in earlier generations, the number of II will grow very quickly. For a time the growth rate of II will exceed that of p(k). At some point it will be unlikely that an II individual will encounter an NI mate, however a few NI persons will still pair with NI mates--for a while.
My question is, after 600 generations, what is a reasonable estimate of the percentage of II in the population? Is is possible that there would be any NI individuals left? Or would we have some sort of dynamic equilibrium between II and NI in which (I think) the former would strongly dominate?
FWIW, the population growth model is $p(k)=4e^{0.012 k}$ with $p(k)$ in millions. For simplicity, I denote the population of non-infected individuals by $N$ and the infected ones by $I$.
Model without soil infection
The following is multiple choice question (with options) to answer.
What effect occurs when a population suddenly gets much smaller, due to natural disaster or other cause? | [
"limitation effect",
"bottleneck effect",
"convergence effect",
"extinction effect"
] | B | Bottleneck effect occurs when a population suddenly gets much smaller. This might happen because of a natural disaster such as a forest fire. By chance, allele frequencies of the survivors may be different from those of the original population. |
SciQ | SciQ-3587 | c
Title: Match blood types in C I have written a solution to the blood-type matching problem, as described at https://projectlovelace.net/problems/blood-types/. The problem is to determine whether a given recipient (in this case, argv[1]) will find a match for a blood transfusion in an array of available donors (argv + 2).
Input blood type: B+
Input list of available blood types: A- B+ AB+ O+ B+ B-
Output: match
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
typedef struct {
enum { O, A, B, AB } abo;
enum { P, M } rh;
} Blood;
const int abo[4][4] = {
{ O, O, O, O }, // O
{ O, A, O, A }, // A // *
{ O, B, O, B }, // B // *
{ O, A, B, AB }, // AB
};
const int rh[2][2] = {
{ P, M }, // P
{ M, M }, // M // *
};
Blood
parse(char *s){
char rh0 = s[strlen(s)-1];
char *abo0 = strdup(s);
abo0[strlen(s)-1] = '\0';
Blood b = {
!strncmp(abo0, "O", 1) ? O
: !strncmp(abo0, "A", 1) ? A
: !strncmp(abo0, "B", 1) ? B
: !strncmp(abo0, "AB", 2) ? AB
: -1,
rh0 == '+' ? P
: rh0 == '-' ? M
: -1,
};
return b;
}
The following is multiple choice question (with options) to answer.
Matching donor and recipient blood types is important because different blood types have different types of what? | [
"antigens",
"charges",
"coagulants",
"antibodies"
] | D | The ABO blood group system is important if a person needs a blood transfusion. A blood transfusion is the process of putting blood or blood products from one person into the circulatory system of another person. The blood type of the recipient needs to be carefully matched to the blood type of the donor. That's because different blood types have different types of antibodies, or proteins, released by the blood cells. Antibodies attack strange substances in the body. This is a normal part of your immune response, which is your defense against disease. |
SciQ | SciQ-3588 | hydrology, meteorology, runoff
The results seem somewhat inconclusive. This topic needs more comprehensive and robust research.
Take-aways
15-20% is the range given by the most recent studies in the intermountain USA.
Solar
radiation was the most closely correlated with trends in sublimation and condensation.
Vegetation impacts sublimation rates.
The following is multiple choice question (with options) to answer.
Heavily vegetated lands are less likely to experience what? | [
"drought",
"expansion",
"flooding",
"rains"
] | C | Heavily vegetated lands are less likely to experience flooding. Plants slow down water as it runs over the land, giving it time to enter the ground. If the ground is too wet to absorb more water, plants still slow the water’s passage. Slower water keeps all the water from entering the stream at once. Wetlands play a key role in minimizing the impacts of floods. Wetlands act as a buffer between land and high water levels. Flooding is often more severe in areas that have been recently logged. |
SciQ | SciQ-3589 | 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.
Unlike fibrous or cartilaginous joints, the articulating bone surfaces at what joint type are not directly connected to each other with fibrous connective tissue or cartilage? | [
"knee joint",
"polymeric joint",
"synovial joint",
"proximal joint"
] | C | which the articulating surfaces of the bones contact each other. Also unlike fibrous or cartilaginous joints, the articulating bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility. |
SciQ | SciQ-3590 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
What do you call the relationship in which members of one species consume members of another species? | [
"competition",
"parasitism",
"exploitation",
"predation"
] | D | Predation is a relationship in which members of one species consume members of another species. The consuming species is called the predator. The species that is consumed is called the prey. In Figure below , the wolves are predators, and the moose is their prey. |
SciQ | SciQ-3591 | 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.
In vertebrates, a system of what structures attached to the endoskeleton enables movement? | [
"muscles",
"tendons",
"tissues",
"nerves"
] | A | Vertebrates have a system of muscles attached to the endoskeleton to enable movement. Muscles control movement by alternately contracting (shortening) and relaxing (lengthening). Generally, muscles work together in opposing pairs. |
SciQ | SciQ-3592 | genetics, cell-biology, embryology, meiosis, gamete
Title: Fertilization of the human egg- where does our centrosome come from? Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can have a centrosome? If this is so, then how did oogenesis happen? ? To answer the first part of your question. The sperm actually introduces two centrosomes. The centrosome then nucleates the new microtubule assembly to form the sperm aster — a step essential for successful fertilization. You can visit these sites Simerly, et al as well as Paweltz, et al
The following is multiple choice question (with options) to answer.
What does the central cell develop into after double fertilization? | [
"endocell",
"exosperm",
"xygote",
"endosperm"
] | D | |
SciQ | SciQ-3593 | electrochemistry, electrolysis
edit: I'm asking about the mechanism when an electrochemical cell is linked to an electrolytic cell, not about the reactions taking place in the electrochemical cell itself, so the question suggested doesn't quite fit the bill.
edit 2: Added a picture to better show my doubts. If the galvanic cell is linked to an electrolytic one as shown here, the galvanic anode and the electrolytic cathode are linked and seemingly acts as a separate cell. The same thing can be said about the other two electrodes. If this is the case, doesn't the galvanic anode and cathode each act independently of one another, and therefore the electrode potential of the individual half cell must be considered? If they are actually linked, how? You seem to be mixing a couple of things. One important clarification regarding
The following is multiple choice question (with options) to answer.
What device is an electrochemical cell or series of cells that produces an electric current? | [
"generator",
"reactor",
"battery",
"magnet"
] | C | A battery is an electrochemical cell or series of cells that produces an electric current. In principle, any galvanic cell could be used as a battery. An ideal battery would never run down, produce an unchanging voltage, and be capable of withstanding environmental extremes of heat and humidity. Real batteries strike a balance between ideal characteristics and practical limitations. For example, the mass of a car battery is about 18 kg or about 1% of the mass of an average car or light-duty truck. This type of battery would supply nearly unlimited energy if used in a smartphone, but would be rejected for this application because of its mass. Thus, no single battery is “best” and batteries are selected for a particular application, keeping things like the mass of the battery, its cost, reliability, and current capacity in mind. There are two basic types of batteries: primary and secondary. A few batteries of each type are described next. |
SciQ | SciQ-3594 | metabolism, nutrition, digestive-system
Title: Do I have to chew for digestion to kick in? Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"? If you had to chew to digest, then beverages like sugary sodas would never be digested or provide calories or nutrients, as you (generally) don't chew when you drink them. No, chewing is not required for digestion or nutrient absorption. Chewing is important when eating solid foods, as the chewing action breaks down and begins to solublize the food, and stimulates the production of saliva, which contains enzymes that begin to break down the food prior to digestion in the stomach and intestines.
The following is multiple choice question (with options) to answer.
Where does digestion begin? | [
"stomach",
"tongue",
"esophogus",
"mouth"
] | D | Figure 23.28 Digestion and Absorption Digestion begins in the mouth and continues as food travels through the small intestine. Most absorption occurs in the small intestine. |
SciQ | SciQ-3595 | gazebo
Title: What are the various joint types available in gazebo?
Revolute, prismatic, continuous and what else?
Could somebody point me to the right resource to look at to get such information.
Thanks.
Originally posted by pmaini on Gazebo Answers with karma: 33 on 2014-12-09
Post score: 3
You can find the joint types supported by SDF in the SDF documentation:
The type of joint, which must be one
of the following: (revolute) a hinge
joint that rotates on a single axis
with either a fixed or continuous
range of motion, (gearbox) geared
revolute joints, (revolute2) same as
two revolute joints connected in
series, (prismatic) a sliding joint
that slides along an axis with a
limited range specified by upper and
lower limits, (ball) a ball and socket
joint, (universal), like a ball joint,
but constrains one degree of freedom,
(piston) similar to a Slider joint
except that rotation around the
translation axis is possible.
Originally posted by NickDP with karma: 186 on 2014-12-09
This answer was ACCEPTED on the original site
Post score: 6
The following is multiple choice question (with options) to answer.
What kind of joints are capable of a wide range of movements, classified as gliding, angular, rotational, or special? | [
"synovial",
"glandular",
"locking",
"fibrous"
] | A | Movement at Synovial Joints The wide range of movement allowed by synovial joints produces different types of movements. The movement of synovial joints can be classified as one of four different types: gliding, angular, rotational, or special movement. Gliding Movement Gliding movements occur as relatively flat bone surfaces move past each other. Gliding movements produce very little rotation or angular movement of the bones. The joints of the carpal and tarsal bones are examples of joints that produce gliding movements. Angular Movement Angular movements are produced when the angle between the bones of a joint changes. There are several different types of angular movements, including flexion, extension, hyperextension, abduction, adduction, and circumduction. Flexion, or bending, occurs when the angle between the bones decreases. Moving the forearm upward at the elbow or moving the wrist to move the hand toward the forearm are examples of flexion. Extension is the opposite of flexion in that the angle between the bones of a joint increases. Straightening a limb after flexion is an example of extension. Extension past the regular anatomical position is referred to as hyperextension. This includes moving the neck back to look upward, or bending the wrist so that the hand moves away from the forearm. Abduction occurs when a bone moves away from the midline of the body. Examples of abduction are moving the arms or legs laterally to lift them straight out to the side. Adduction is the movement of a bone toward the midline of the body. Movement of the limbs inward after abduction is an example of adduction. Circumduction is the movement of a limb in a circular motion, as in moving the arm in a circular motion. |
SciQ | SciQ-3596 | biochemistry, endocrinology, chemical-communication
Title: Single hormone opposite effects Often, a smooth response to a hormone means that some processes must be sped up and others must be slowed down.
How can a single hormone have opposite effects like this? An hormone is not different from most other molecules. To have an effect on a cell it binds to a (more or less specific) receptor, located either on the plasma membrane or inside the cell, and it initiates an intracellular cascade of events1.
There are several ways an hormone can have different effects:
there can be multiple receptors for the same hormone. For instance, prolactin can bind to two receptors, called prolactin receptor (PRL-R) short and long form. The short form of the receptor has been shown to lack the ability to promote milk protein genes transcription (See Lesueur et al., PNAS - 1991).
the same receptor can be coupled to different intracellular pathways in different cell types / physiological conditions, thus resulting in different effects.
each cell type/tissue expresses a set of protein that will interact in a different manner with the intracellular cascade promoted by the hormone.
an hormone can interact with receptors for other molecules. For instance allopregnanolone, a metabolite of progesterone, is a potent agonist of the GABA-A receptor, giving it anxiolitic properties.
The following is multiple choice question (with options) to answer.
Hormones vary widely in molecular size and type as well as? | [
"simple regulators",
"local regulators",
"foreign regulators",
"strange regulators"
] | B | |
SciQ | SciQ-3597 | 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 kingdom of organisms constitutes up to 20 percent of all living things on earth in mass? | [
"vertebrates",
"sporozoans",
"archaeans",
"protists"
] | C | Not all archaeans live in extreme conditions. In fact, archaeans are now known to live just about everywhere on Earth. They make up as much as 20 percent of Earth's total mass of living things. |
SciQ | SciQ-3598 | classification, image-recognition, pattern-recognition, clustering
Title: How do we know the classification boundaries of the data? Consider an image classification problem. Conceptually, we then have some high dimensional space where all the images can be represented as points, and having large enough labeled data set we can build a classifier. But how do we know that our data in this space has some structure? Like this one in two-dimensional case:
If we have a data set with images of, say, cats and dogs, why these two classes are not just uniformly mixed with each other but have some distribution or shape in appropriate space? Why it cannot be like this: This is the classic question of what structure is or can be. It relates directly to the concepts of generalization, pattern recognition, over-fitting in surface fitting strategies, and learning tabula rasa, Latin for blank slate. The underlying questions are these:
How can it be determined whether the organization of data in a set, which appears to correlate well with model $\mathbb{A}$, isn't just a random data set that merely appears to have $\mathbb{A}$ organization.
How can it be determined whether the organization of data in a set, which appears to correlate well with model $\mathbb{A}$, isn't generated by a phenomenon that generally exhibits organization that correlates well with $\mathbb{B}$?
How can we determine the interrelationship between $\mathbb{A}$ and $\mathbb{B}$, especially since inclusion and overlap relates to the above question?
The following is multiple choice question (with options) to answer.
Scientists often classify or organize different objects based on their what? | [
"experimental properties",
"behavioral traits",
"physical properties",
"independent variables"
] | C | |
SciQ | SciQ-3599 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
The primary substance that human cells, and ultimately human beings, are made up of is what? | [
"gas",
"oil",
"air",
"water"
] | D | The Water (Hydrologic) Cycle Water is the basis of all living processes. The human body is more than 1/2 water and human cells are more than 70 percent water. Thus, most land animals need a supply of fresh water to survive. However, when examining the stores of water on Earth, 97.5 percent of it is non-potable salt water (Figure 46.12). Of the remaining water, 99 percent is locked underground as water or as ice. Thus, less than 1 percent of fresh water is easily accessible from lakes and rivers. Many living things, such as plants, animals, and fungi, are dependent on the small amount of fresh surface water supply, a lack of which can have massive effects on ecosystem dynamics. Humans, of course, have developed technologies to increase water availability, such as digging wells to harvest groundwater, storing rainwater, and using desalination to obtain drinkable water from the ocean. Although this pursuit of drinkable water has been ongoing throughout human history, the supply of fresh water is still a major issue in modern times. |
SciQ | SciQ-3600 | genetics, molecular-genetics, mutations, genetic-code, trna
The genetic code is nearly universal, and the arrangement of the codons in the standard codon table is highly non-random. The three main concepts on the origin and evolution of the code are the stereochemical theory, according to which codon assignments are dictated by physico-chemical affinity between amino acids and the cognate codons (anticodons); the coevolution theory, which posits that the code structure coevolved with amino acid biosynthesis pathways; and the error minimization theory under which selection to minimize the adverse effect of point mutations and translation errors was the principal factor of the code’s evolution. These theories are not mutually exclusive and are also compatible with the frozen accident hypothesis, i.e., the notion that the standard code might have no special properties but was fixed simply because all extant life forms share a common ancestor, with subsequent changes to the code, mostly, precluded by the deleterious effect of codon reassignment.
They then review a variety of evidence for each theory, from which I will present one example.
Is the genetic code optimal?
They note a 1991 paper that used biophysical properties of amino acids and estimated that a randomly selected genetic code was ~0.01% likely to be at least as robust as the existing genetic code. In other words, the code seems to have at least somewhat minimized possible errors. So, the existing code is at least well above-average in terms of possible codes, and it's possible that the reason no better codes have been explored is that it's trapped in a local minimum of the code landscape (see Figure 3 from that paper here).
They go on to discuss this in more detail. I personally find other evidence about the "coevolution" and "collective evolution" theories interesting, but obviously it is hard to repeat a multibillion year experiment.
The following is multiple choice question (with options) to answer.
The genetic code is universal, unambiguous, and what else? | [
"functional",
"novel",
"efficient",
"redundant"
] | D | 6. The genetic code is universal, unambiguous, and redundant. Explain what this means and why it is important. |
SciQ | SciQ-3601 | homework-and-exercises, electromagnetism
Title: Force on a charged particle in a field of an EM wave For example if there is a charge q with mass m travelling with a velocity v "in the field" of a plane electromagnetic wave that is travelling in the z direction (in free space). My question is what would the force and direction (if any) be if the particle was travelling in the same direction as the wave? If it's a positive charge, the particle moves in the direction of the electric field and vice versa for a negative charge.
However, there also exists another force called the Lorentz force. It essentially states that, if a particle is moving with a velocity perpendicular to a magnetic field, a force is produced in a direction mutually perpendicular to the velocity and magnetic field.
To sum up the forces acting on a moving particle by an electric and magnetic field:
$$ {\vec F} = q({\vec E} + {\vec v}\times{\vec B}) $$
Use this image to deduce the motion of a proton and electron that is travelling in the same direction as the propagation of an electromagnetic wave:
The following is multiple choice question (with options) to answer.
An electromagnetic wave begins with what movement by an electrically charged particle? | [
"momentum",
"diffusion",
"acceleration",
"vibration"
] | D | An electromagnetic wave begins when an electrically charged particle vibrates. This causes a vibrating electric field, which in turn creates a vibrating magnetic field. The two vibrating fields together form an electromagnetic wave. |
SciQ | SciQ-3602 | neuroscience, brain, neurophysiology, development, synapses
Title: How do neurons find each other? Neurons form complicated networks in brains, but their connections can't be random (at least not entirely). Brains function similarly among all members of individual species, and that functionality is largely dependent on neuron organization. Furthermore, various brain regions have predictable functions, and there are even parts of the brain where specific cells carry out specialized functions (place cells are an interesting example).
Great! We know neurons can organize into very complex networks, but how? They need to find each other, somehow.
The best I can guess is that either:
Neurons find other target neurons with specific chemical signals.
Neurons don't "find" each other, exactly, but grow in predetermined shapes from from set locations. In this case, the connections would simply be due to neurons bumping into each other as they grow in their predetermined paths.
Or both.
In the first case, there would be a mechanism for searching each other out. In the second, there would be a mechanism for staying in one spot (and growing from there). What are the names of said mechanisms? How do I find out more about them? Q: We know neurons can organize into very complex networks, but how?
The answer is your first guess: Neurons find other target neurons with specific chemical signals.
Q: What are the names of said mechanisms?
This process is called axon guidance, by which the growth cones of developing axons are directed to reach their targets. This process depends upon a slew of cellular and molecular cues. The first axons to grow in any particular brain region are called pioneer axons and are the most dependent upon these cues. Later axons are able to follow (and diverge from) previous axons by the interaction of cell adhesion molecules on their surfaces. Dendritic development is also important for your question, but dendrites tend not to travel as far.
Here are some of the molecules that we know to participate in axon guidance:
Cell adhesion molecules and substrate adhesion molecules, including IgSF CAMs and cadherins
Some chemokines, e.g. CXCL12
Netrins, ephrins, and semaphorins
Slits, via the Slit-Robo cell signaling pathway
Developmental morphogens, e.g. Wnts and Hedgehog
The following is multiple choice question (with options) to answer.
What are the sharp projections that specialized cells grow called? | [
"spicules",
"ossicles",
"antlers",
"cilia"
] | A | Some of the specialized cells grow short, sharp projections called spicules. Spicules make up the sponge’s internal skeleton, or endoskeleton. The endoskeleton helps to support and protect the sponge. |
SciQ | SciQ-3603 | thermodynamics, water, phase-transition, surface-tension
Title: Formation of water droplets Suppose several small water droplets are formed from a big blob of water at room temperature. Will the temperature of resultant water droplets or the surrounding air decrease? Consider it as an isolated system. (I understand that when water droplets are formed from the big blob the surface area increases and so the molecules have to work against cohesive forces since more molecules come to the surface due to increase in area. But I can't get what happens after that.) You're nearly at the answer. Forcing the system to have more surface area requires energy (because some bonds are relatively unsatisfied) that initially comes from the thermal energy. The water thus cools down until heat transfer with the environment brings it back to room temperature. (During that process, the surrounding air necessarily cools down temporarily as well.)
The surface energy of water is about 0.072 J/m² at room temperature, which—in conjunction with the heat capacity—can help you estimate the magnitude of the resulting cooling.
The following is multiple choice question (with options) to answer.
What is formed when water vapor in the air condenses into tiny droplets? | [
"hail",
"rain",
"smoke",
"fog"
] | D | Rock bands often use special stage effects, like the fake fog in this picture. Real fog forms when water vapor in the air condenses into tiny droplets of water. The fake fog shown here formed when solid carbon dioxide changed directly to carbon dioxide gas. |
SciQ | SciQ-3604 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
The main components of the circulatory system are the heart, blood vessels, and what else? | [
"brain",
"blood",
"lungs",
"nerves"
] | B | The circulatory system can be compared to a system of interconnected, one-way roads that range from superhighways to back alleys. Like a network of roads, the job of the circulatory system is to allow the transport of materials from one place to another. As described in Figure below , the materials carried by the circulatory system include hormones, oxygen, cellular wastes, and nutrients from digested food. Transport of all these materials is necessary to maintain homeostasis of the body. The main components of the circulatory system are the heart, blood vessels, and blood. |
SciQ | SciQ-3605 | thermodynamics, thermal-radiation, physical-chemistry, biophysics, solar-cells
Title: Extreme life - energy source for living tens of kilometers underground? Living cells were found up to at least 12 miles underground (article), and in other extreme places (BBC survey article), for which beside the problem of just surviving in such extreme conditions, a basic physics thermodynamical question is: what energy source it is based on?
And in such extreme temperatures there is needed a lot of energy just to fight 2nd law of thermodynamics - actively protect cell's structures against thermalization.
Such energy source needs to be relatively stable for past billions of years - what seems to exclude chemical energy sources (?)
One stable energy source in such high temperatures are thermal IR photons, and thermophotovoltaics is generally able to harvest energy from them. However, cell living in such extreme conditions would rather have the same temperature, hence 2nd law seem to forbid harvesting energy from such IR photons? Chemical.
As the Wikipedia entry on Lithoautotroph puts it (restricting ourselves to the deep underground forms):
derives energy from reduced compounds of mineral origin
which they do through inorganic oxidation (see, e.g., Lessons from the Genome of a Lithoautotroph: Making Biomass from Almost Nothing) or other reactions, such as the reaction of formate (HCOO-) and water, to form bicarbonate and hydrogen (Extremophile microbes survive only on energy from formate oxidation).
The following is multiple choice question (with options) to answer.
From what do tubeworms found deep in the galapagos rift get their energy from? | [
"chemosynthetic plants",
"chemosynthetic fish",
"chemosynthetic bacteria",
"chemosynthetic viruses"
] | C | Tubeworms deep in the Galapagos Rift get their energy from chemosynthetic bacteria. Tubeworms have no mouth, eyes or stomach. Their survival depends on a symbiotic relationship with the billions of bacteria that live inside them. These bacteria convert the chemicals that shoot out of the hydrothermal vents into food for the worm. |
SciQ | SciQ-3606 | # Mathematical Physics: Differential equation of a raindrop
I hope this is a suited question for this site since it contains a mix of physics and mathematics. In case I should post this on the physics stackexchange site, please let me know.
A spherical raindrop is falling from the sky. Because of the humid atmosphere the raindrop will gain mass during his fall. The increase in mass per time is proportional to the current surface area.
1. Find an equation for the radius of the drop as a function of time ($r(t)$). ($r(0) =r_0$)
2. Find and solve the equation of motion for the raindrop. The equation of motion should depend on $r_0$
My work so far:
Mass: $m(t)=\frac{4}{3} \pi r(t)^3 \rho$
Sufrace Area: $A(t)=4\pi r(t)^2$
\begin{aligned} & \implies \frac{dm(t)}{dt}=\frac{d}{dt}(\frac{4}{3}\pi r(t)^3 \rho)=4 \pi r(t)^2 r'(t)\rho\\ & \iff 4 \pi \rho r(t)^2 r'(t)=\lambda 4 \pi r(t) ^2 \iff r'(t)=\frac{\lambda}{\rho} \iff \frac{dr}{dt}=\frac{\lambda}{\rho} \\ & \iff \int dr = \frac{\lambda}{\rho} \int dt \iff r(t)=\frac{\lambda}{\rho}t+c \\ & \color{blue}{\implies r(t)=\alpha t+r_0} \space \space \space \space \space \space \space \space \space \space \space \text{where}\space \space\alpha=\frac{\lambda}{\rho} \end{aligned}
Equation of motion:
Gravitational Force: $mg$
The following is multiple choice question (with options) to answer.
What is water falling from the sky called? | [
"temperature",
"snow",
"precipitation",
"acid"
] | C | |
SciQ | SciQ-3607 | fracking, clathrates
Title: Do we know how large deposits of methane clathrates were formed in permafrost regions? We can see that there are large buildups of methane clathrates in permafrost regions. This seems different to the buildups of natural gas which fracking releases, which appear to have just come from escaped gases from oil/coal deposits.
My question is: Do we know how large deposits of methane clathrates were formed in permafrost regions? Rotting vegetation generates methane, or marsh gas as it is sometimes called. The most obvious method by which clathrates were formed in Arctic regions is that many years ago during summer and autumn, rotting vegetation produced methane, which combined with water at cold temperatures to produce methane ice, otherwise known as clathrates. Extremely cold temperatures are not necessary to form clathrates. They form at the bottom of deep seas, where the temperature even in the tropics is a constant 4 or 5 C. There are huge deposits of clathrates on the deep ocean floor, and there has been talk of exploiting them commercially.
A theory to explain the Permo-Triassic extinction event of 250 million years ago hypothesises that super-eruptions in the Siberian Traps super-volcano raised temperatures enough to release vast quantities of methane from tundras and ocean beds, so that with the additional greenhouse gas the average temperature rose by about 10 C, causing the extinction of nearly 90 percent of all large animals, a greater mass extinction than the better known event at the end of the Cretaceous.
The following is multiple choice question (with options) to answer.
Coal, oil and natural gas are types of what formed from the remains of once living organisms? | [
"fossil compounds",
"crop fuels",
"living fossils",
"fossil fuels"
] | D | Coal, oil and natural gas are all fossil fuels formed from the remains of once living organisms. |
SciQ | SciQ-3608 | heat, physical-chemistry
Title: Why does burning magnesium explode when sprinkled with water? Magnesium powder burns extremely well and reaches temperatures of 2500°C. However, attempts to extinguish such a magnesium fire with conventional water (e.g. from a garden hose) only make it worse: the flame grows astronomically and the whole thing gets even hotter. Why is this? Magnesium reacts with water to produce hydrogen and a lot of heat. Metallic magnesium reacts only slowly, but magnesium vapour, produced when Mg burns, reacts extremely quickly due to the high temperature and efficient mixing, and produces heat very rapidly. Hence the explosion when water is added to burning magnesium.
The following is multiple choice question (with options) to answer.
In a hot water heater, burning fuel causes the water to get hot because combustion is what type of reaction? | [
"biochemical",
"geothermal",
"exothermic",
"endothermic"
] | C | A: A hot water heater increases the temperature of water in most homes. Many hot water heaters burn a fuel such as natural gas. The burning fuel causes the water to get hot because combustion is an exothermic reaction. |
SciQ | SciQ-3609 | forces, newtonian-gravity
Title: A misconception in an application of Newton's laws When a body is kept in ground, and is at rest, the downward gravitational pull is balanced exactly by the Normal Reaction if we assume the earth to be an inertial frame. But this would mean that any external force provided to that body would lead to its motion. if this was the case, moving things both heavy and light would be same. what is the external force that abstains it from happening? I think the apparent paradox is driven by a misunderstanding of the very nature of reaction forces. A reaction force is a force $F_N$ perpendicular to a surface which counterbalance the gravitational pull, or any other force perpendicular to the surface.
This is because reaction force are basically what prevent two bodies to occupy the same volume, and their microscopically origin is the electrostatic (Coulomb) repulsion.
They are always normal to the surface and with outward direction.
Imagine now that the body on the ground has mass $m$ and one applies an external force $F_E$ perpendicular to the ground, pulling upwards. We have
$$F_E-m g+F_N=m a,$$
where we choose our $x$ axis perpendicular to the ground and directed upwards.
The force $F_N$ is perpendicular to the ground (outward direction), i.e., $F_M\ge0$ for our axis choice.
Now there are two cases:
1) $F_E<mg$
in this case the normal reaction is $F_N=mg - F_E>0$, and the body does not move ($a=0$). Intuitively, the force $F_E$ is not enough to lift the body.
2) $F_E>mg$
in this case one would have $F_N=mg - F_E<0$, i.e., the normal force would push the body to the ground. But this contradicts the assumption since $F_N<0$. Therefore in this case $F_N=0$ and $F_E-m g=m a\neq 0$, i.e., the body has a finite acceleration.
The following is multiple choice question (with options) to answer.
What is a force that opposes motion? | [
"momentum",
"friction",
"thrust",
"tension"
] | B | Friction is a force that opposes motion. Any two objects in contact have what is called a mutual coefficient of friction. To find the force of friction between them, we multiply the normal force by this coefficient. Like the forces above, it arises due to electromagnetic interactions of atoms in two objects. There are actually two coefficients of friction: static and kinetic. Static friction will oppose initial motion of two objects relative to each other. Once the objects are moving, however, kinetic friction will oppose their continuing motion. Kinetic friction is lower than static friction, so it is easier to keep an object in motion than to set it in motion. There are some things about friction that are not very intuitive:. |
SciQ | SciQ-3610 | electromagnetism, magnetic-fields, electric-fields, classical-electrodynamics, geometric-optics
See Einzel lens: http://en.wikipedia.org/wiki/Einzel_lens
See Quadrupole: http://en.wikipedia.org/wiki/Quadrupole
The following is multiple choice question (with options) to answer.
What is another term for a hand lens? | [
"seeing glass",
"magnifying glass",
"traversing glass",
"projecting glass"
] | B | An example of a lens is a hand lens, also called a magnifying glass. This type of lens makes objects look bigger than they really are. How do you think this happens?. |
SciQ | SciQ-3611 | human-biology, human-anatomy, terminology, anatomy, etymology
Title: Why is the opposite of plantar flexion called "dorsiflexion"? Why is the action of flexing the foot so that the toes move anteriorly/superiorly (i.e. in the direction opposite that which they move during plantar flexion) described as "dorsiflexion?" In the same vein, why is the top surface of the foot called the "dorsal surface?"
If anything, the action opposite to plantar flexion moves the foot in the ventral direction, doesn't it? And surely if you've ever seen a human in the anatomical position, you can see that there's nothing dorsal about the top surface of the foot - it's superior, perhaps, but by no means dorsal. Anatomical terms must be able to fit a wide variety of organisms, from insects to fish, dogs, horses, chimpanzees to humans. That's why the terms are sometimes confusing to people who are thinking only of bipedal humans.
In anatomy, the dorsum is the upper side of animals that typically run fly, swim or crawl in a horizontal position. In vertebrates the dorsum contains the backbone. In such an animal the "ground side" is the ventrum.
Due to varied orientation on quadrupedal mammals (where the term is more appropriately used) the "back"-side of the hand, the "top"-side of the foot and the upper surface of the tongue are referred to by the term dorsum.
Does this picture help? Note the dorsal surfaces of the body, muzzle, feet.
In anatomy, the sole of the foot is called the plantar surface. The top of the foot is called the dorsum of the foot. (Imagine us walking on all fours like apes.) Therefore when you extend your foot, it's called plantar flexion; when you flex your foot upwards towards your head, it's called dorsiflexion.
Similarly, the arteries feeding the bottom of your foot form the plantar arch. Those feeding the top are the dorsal artery (or the dorsalis pedis).
Because anatomy must describe other animals than ourselves with other orientations, it must be consistent. In a quadruped, the dorsum of the tongue and the feet do actually point to it's "back" surface. See the picture below:
The following is multiple choice question (with options) to answer.
The anterior half of the foot is formed by the five what type of bones? | [
"conidia bones",
"metatarsal bones",
"malignancy bones",
"conidia bones"
] | B | Metatarsal Bones The anterior half of the foot is formed by the five metatarsal bones, which are located between the tarsal bones of the posterior foot and the phalanges of the toes (see Figure 8.19). These elongated bones are numbered 1–5, starting with the medial side of the foot. The first metatarsal bone is shorter and thicker than the others. The second metatarsal is the longest. The base of the metatarsal bone is the proximal end of each metatarsal bone. These articulate with the cuboid or cuneiform bones. The base of the fifth metatarsal has a large, lateral expansion that provides for muscle attachments. This expanded base of the fifth metatarsal can be felt as a bony bump at the midpoint along the lateral border of the foot. The expanded distal end of each metatarsal is the head of the metatarsal bone. Each metatarsal bone articulates with the proximal phalanx of a toe to form a metatarsophalangeal joint. The heads of the metatarsal bones also rest on the ground and form the ball (anterior end) of the foot. |
SciQ | SciQ-3612 | kinematics, terminology, velocity, inertial-frames
Title: Is there a word to describe when things are moving individually, but have a net velocity of zero? I know this is a strange question, but I know there must be a word for it.
So imagine a case where, taken as a whole, the net velocity of all particles equals zero, but each individual particle is moving. Here is what I am picturing:
For root words, I tried quasistatic, but it doesn't seem to have the same meaning since it is emphasizing the stability rather than the movement. I have thought of metastatic, using *meta- meaning change and *sta- which has the same root in stasis, but that one has the unfortunate connotation of cancer. As you can see, I am not at all well versed in linguistics or etymology, so help would be much appreciated. It might be described as pedesis or as random motion.
The picture shows the velocities of many particles (as in a gas the molecules all move around). Velocity is a vector: it has a speed and it has direction. In 3 dimensions this means that it has three components mutually at right angles: for present convenience, call them up/down, left/right, towards/away.
The net velocity in this case is the average velocity of all particles. To say it is zero is to say that the averages of each component of the vectors is zero. There is as much motion left as right, up as down, towards as away.
vector = a representation of something that has both direction and size
Cambridge
Note that the average velocity is zero although the average speed is not. The particles are all bouncing around in the box with various speeds but as a group they are going nowhere, so the average velocity is zero.
The group of particles is showing "random motion".
Brownian motion, or pedesis (from Ancient Greek: πήδησις /pɛ̌ːdɛːsis/ "leaping"), is the random motion of particles suspended in a medium (a liquid or a gas).
Wikipedia
The following is multiple choice question (with options) to answer.
What adjective describes the movements that propel the feces during elimination? | [
"convulsive",
"peristaltic",
"enzymatic",
"hyperplastic"
] | B | The rectum (Figure 16.6) stores feces until defecation. The feces are propelled using peristaltic movements during elimination. The anus is an opening at the far-end of the digestive tract and is the exit point for the waste material. Two sphincters regulate the exit of feces, the inner sphincter is involuntary and the outer sphincter is voluntary. Accessory Organs The organs discussed above are the organs of the digestive tract through which food passes. Accessory organs add secretions and enzymes that break down food into nutrients. Accessory organs include the salivary glands, the liver, the pancreas, and the gall bladder. The secretions of the liver, pancreas, and gallbladder are regulated by hormones in response to food consumption. The liver is the largest internal organ in humans and it plays an important role in digestion of fats and detoxifying blood. The liver produces bile, a digestive juice that is required for the breakdown of fats in the duodenum. The liver also processes the absorbed vitamins and fatty acids and synthesizes many plasma proteins. The gallbladder is a small organ that aids the liver by storing bile and concentrating bile salts. The pancreas secretes bicarbonate that neutralizes the acidic chyme and a variety of enzymes for the digestion of protein and carbohydrates. |
SciQ | SciQ-3613 | inorganic-chemistry, redox, mole
Regarding the above question, how would one solve it?
Would it be valid to simply say that I know that 6 electrons are being transferred because we have this skeleton equation (balanced for charge):
$$\ce{Al -> Al(OH2)6^3+ + 6 e-}$$
And given that 6 electrons are being transferred and that hydrogen is a reduction product, we must obtain hydrogen from some source in this system. The source would probably be hydronium ion, since hydronium ion is less stable than water. Plus abstracting protons from water to form hydrogen gas wouldn't make much sense in strongly acidic solution (we'd be forming hydroxide ions as well)! And knowing the following reaction:
$$\ce{2 H+ + 2 e- -> H2}$$
Can we just say since we know that 6 electrons are being moved, and that hydrogen gas is a product, we know that the immediately above reaction is occurring, and according to its stoichiometry, 2 moles of electrons yields 2 moles of hydrogen gas? You simply build the half reactions and add them up so you can see how many moles of hydrogen gas are produced by a mole of Aluminium being oxidised. (Note: Your first equation is unbalanced.)
\begin{aligned}\ce{
(1)&& Al + 6H2O &-> Al(OH2)_{6}^{3+} + 3e^{-}&|\cdot2\\
+ (2)&& 2H3O+ + 2e^{-} &-> H2 ^ + 2H2O &|\cdot3\\\hline
(3)&& 2Al + 12H2O + 6H3O+ &-> 2Al(OH2)_{6}^{3+} + 3H2 ^ + 6H2O\\
(4)\equiv(3)&& 2Al + 6H2O + 6H3O+ &-> 2Al(OH2)_{6}^{3+} + 3H2 ^ \\
The following is multiple choice question (with options) to answer.
What is transferred in an acid-base reaction | [
"bonding ion",
"hydrogen ion",
"friendly ion",
"calcium ion"
] | B | Acid-base reactions involve a transfer of a hydrogen ion instead of an electron. Acid-base reactions, like the one below, are also not redox reactions. |
SciQ | SciQ-3614 | planetary-formation, size, brown-dwarf, red-dwarf, hot-jupiter
Title: Existence of planets larger than their host star? The mass region of objects between ~ 0.5 Jupiter masses and 80 Jupiter masses (gas giants through to brown dwarfs and red dwarfs) is typified by an almost flat relationship with object diameter. There are planets out there which are larger in diameter than some of the smallest stars.
The smallest (currently fusing) star known, EBLM-J0555-57, is estimated to be slightly larger than Saturn (at about 59000 km radius with 85 times Jupiter's mass).
One of the largest planets known that isn't a suspected brown dwarf, WASP-79b is estimated to be twice Jupiter's diameter at 0.9 times Jupiter's mass. Many Hot jupiters and puffy planets with similar measurements are known.
How likely are there to be systems where a planet is larger in diameter than its host star? Are there any examples known?
I am looking for currently fusing stars only, which rules out pulsar planets, etc. The answer to the question depends on the exact definition of planet that is used.
A possible example is the L dwarf 2M 0746+20 (2MASS J07464256+2000321) and its planet 2M 0746+20 b.
The radius of the planet is 12% greater than the radius of the star.
$$\begin{array}{lll}
\hline
\text{} & \text{Mass} & \text{Radius}\\
\hline
\text{Planet} & 12.21 \cdot M_J & 0.970 \cdot R_J\\
\text{Star} & 83.79 \cdot M_J & 0.089 \cdot R_{Sun} = 0.866 \cdot R_J\\
\hline
\end{array}$$
Note: The reported planet mass of $12.21 (± 0.4) \cdot M_J$ is slightly below the deuterium burning limit of 13 Jupiter masses.
The following is multiple choice question (with options) to answer.
What is the largest planet in our solar system? | [
"mars",
"earth",
"uranus",
"jupiter"
] | D | Jupiter is the largest planet in our solar system. Jupiter is named for the king of the gods in Roman mythology. The Romans named the largest planet for their most important god. They followed the tradition of the Greeks, who had similarly named the planet Zeus. The Romans built a temple to Jupiter on the hill. |
SciQ | SciQ-3615 | electromagnetism, magnetic-fields, electricity, electric-current, electromagnetic-induction
Title: How to generate electric current without a permanent magnet? The question is pretty simple:
Can we build a device that coverts mechanical work in electric current1 without employing a permanent magnet and without access to any external source of current?
The restrictions in place seem to rule out the possibility of current generation via induction; and I cannot think of another practical method. I have heard that industrial alternators sometimes work with electromagnets, but we don't have access to any external source of current, so this path doesn't seem viable.
Do we really need stupid magnetic rocks to produce current? Unacceptable.
To be more specific and minimize to risk of misunderstandings: my question is more or less equivalent to the following one
Can we build a device, powered by hand via some sort of rotating lever, that produces electric current, crucially without employing any external current and without any permanent magnet?
[1]: Usable electric current, let's say sufficient to properly power up a lamp; doesn't matter if AC or DC. Doesn't a battery do this? Also, capacitors.
EDIT: With the edit, it looks like the premise of your question could be satisfied by a Van de Graff generator:
https://en.wikipedia.org/wiki/Van_de_Graaff_generator
which uses friction to strip electrons from a substance, and create an electrostatic potential.
The following is multiple choice question (with options) to answer.
What does the ubiquitous generator use to generate currents? | [
"gravity",
"magnetism",
"inertia",
"water"
] | B | The hint of symmetry between electricity and magnetism found in the preceding chapter will be elaborated upon in this chapter. Specifically, we know that a current creates a magnetic field. If nature is symmetric here, then perhaps a magnetic field can create a current. The Hall effect is a voltage caused by a magnetic force. That voltage could drive a current. Historically, it was very shortly after Oersted discovered currents cause magnetic fields that other scientists asked the following question: Can magnetic fields cause currents? The answer was soon found by experiment to be yes. In 1831, some 12 years after Oersted’s discovery, the English scientist Michael Faraday (1791–1862) and the American scientist Joseph Henry (1797–1878) independently demonstrated that magnetic fields can produce currents. The basic process of generating emfs (electromotive force) and, hence, currents with magnetic fields is known as induction; this process is also called magnetic induction to distinguish it from charging by induction, which utilizes the Coulomb force. Today, currents induced by magnetic fields are essential to our technological society. The ubiquitous generator—found in automobiles, on bicycles, in nuclear power plants, and so on—uses magnetism to generate current. Other devices that use magnetism to induce currents include pickup coils in electric guitars, transformers of every size, certain microphones, airport security gates, and damping mechanisms on sensitive chemical balances. Not so familiar perhaps, but important nevertheless, is that the behavior of AC circuits depends strongly on the effect of magnetic fields on currents. |
SciQ | SciQ-3616 | civil-engineering
Other things that can be done is to place hay bales, or rocks, on the soil slope and on the slope above the deposited soil. These can help to reduce the speed of surface water running down the slope.
If hay bales are used they should be placed in a staggered, off-set pattern, so that long drainage channels, which would lead to the formation of erosion gullies, are not created by the bales.
Moonscaping of the upper natural slope, above the deposited soil slope would also help in preserving the deposited soil slope.
The following is multiple choice question (with options) to answer.
What prevents soil erosion on a hillside that is being farmed? | [
"irrigation",
"terracing",
"no-till farming",
"slash-and-burn"
] | B | Although the hillside is interesting, that's not why this was done. Terracing prevents soil erosion on a hillside that is being farmed. Many techniques can be utilized to reduce soil erosion. |
SciQ | SciQ-3617 | molecular-biology, molecular-genetics, development, sex
Quote from a Review (Yao 2005):
We have just begun to glimpse into the mechanisms underlying ovarian development. Convincing evidence challenges us to reconsider the existing paradigm that describes ovarian development as a default system. The default concept was first proposed in the early 1950s when Jost performed the groundbreaking experiments to demonstrate mechanisms of sex differentiation of reproductive tracts (Jost, 1947, 1953, 1970). The term “default” was not originally intended to describe the developmental status of the ovary. Instead, it is referred to the female reproductive tract or the Mullerian duct based on the fact that the female reproductive tract forms in both XX and XY individuals in the absence of gonads. Indeed, now it has become evident that early ovarian development is an active process involving intrinsic cell fate decisions and complex crosstalks between germ cells and somatic cells. Most intriguingly, the appearance of testicular structures in XX individuals where Sry and its downstream components are absent further raises the improbable question: Could the testicular development be default after all?
The following is multiple choice question (with options) to answer.
What do the external female reproductive structures are collectively referred to? | [
"vulva",
"endometrium",
"cervix",
"Clitoris"
] | A | The external female reproductive structures are referred to collectively as the vulva . They include the labia (singular, labium ), which are the “lips” of the vulva. The labia protect the vagina and urethra, both of which have openings in the vulva. |
SciQ | SciQ-3618 | immunology
Title: Is Plasmablast a precursor of Plasma cell? I read it in Roitt's Essential Immunology.
Plasmablasts are precursor cells of short- and long-lived plasma cells and
are generally described as a proliferating fraction of
antibody-secreting cells, often found in the bloodstream
emigrating to organs such as the bone marrow.
I coudn't find any authentic source repeating the same.
Is it true? Is this book authentic enough to follow? Antigen activated B-cells enter the germinal centre dark zone to form centroblasts which undergo somatic hypermutation. These then form centrocytes in the light zone. The various possibilities/routes the centrocyte can take are shown in the following figure. If the centrocyte undergoes a class switch recombination, it becomes a plasmablast.
A plasmablast is defined as
Plasmablast
The B-cell lineage precursor of non-dividing plasma cells, which has the capacity to divide and that has migratory potential.
Once it matures as a plasma cell, it is out in the blood secreting soluble immunoglobulins or antibodies.
Another important definition to mentioned here would be of antibody secreting cells.
Antibody-secreting cells
A term that denotes both proliferating plasmablasts and non-proliferating plasma cells. The term is used when both cell types might be present
So, yes, they indeed are a precursor of plasma cells.
Also, it is necessary to clarify here that although both plasma cells and plasmablasts are antibody secreting cells, plasma cells lack membrane bound antibodies while plasmablasts retain them.
Finally, this is just the germinal centre response that is shown over here. Plasma cells and plasmablasts can also form in an extrafollicular response in extrafollicular sites in the spleen or in the medullary cords of the liver. That's another story altogether!
For a more detailed explanation, have a look at my other answer.
Image and reference: http://www.nature.com/nri/journal/v8/n1/full/nri2217.html
The following is multiple choice question (with options) to answer.
What is another name for collar cells? | [
"sporozoans",
"enzymes",
"clutches",
"choanocytes"
] | D | Morphology of Sponges The morphology of the simplest sponges takes the shape of a cylinder with a large central cavity, the spongocoel, occupying the inside of the cylinder. Water can enter into the spongocoel from numerous pores in the body wall. Water entering the spongocoel is extruded via a large common opening called the osculum. However, sponges exhibit a range of diversity in body forms, including variations in the size of the spongocoel, the number of osculi, and where the cells that filter food from the water are located. While sponges (excluding the hexactinellids) do not exhibit tissue-layer organization, they do have different cell types that perform distinct functions. Pinacocytes, which are epithelial-like cells, form the outermost layer of sponges and enclose a jelly-like substance called mesohyl. Mesohyl is an extracellular matrix consisting of a collagen-like gel with suspended cells that perform various functions. The gel-like consistency of mesohyl acts like an endoskeleton and maintains the tubular morphology of sponges. In addition to the osculum, sponges have multiple pores called ostia on their bodies that allow water to enter the sponge. In some sponges, ostia are formed by porocytes, single tube-shaped cells that act as valves to regulate the flow of water into the spongocoel. In other sponges, ostia are formed by folds in the body wall of the sponge. Choanocytes (“collar cells”) are present at various locations, depending on the type of sponge, but they always line the inner portions of some space through which water flows (the spongocoel in simple sponges, canals within the body wall in more complex sponges, and chambers scattered throughout the body in the most complex sponges). Whereas pinacocytes line the outside of the sponge, choanocytes tend to line certain inner portions of the sponge body that surround the mesohyl. The structure of a choanocyte is critical to its function, which is to generate a water current through the sponge and to trap and ingest food particles by phagocytosis. Note the similarity in appearance between the sponge choanocyte and choanoflagellates (Protista). This similarity suggests that sponges and choanoflagellates are closely related and likely share a recent common ancestry. The cell body is embedded in mesohyl and contains all organelles required for normal cell function, but protruding into the “open space” inside of the sponge is a mesh-like collar composed of microvilli with a single flagellum in the center of the column. The cumulative effect of the flagella from all choanocytes aids the movement of water through the sponge: drawing water into the sponge through the numerous ostia, into the spaces lined by choanocytes, and eventually out through the osculum (or osculi). In the meantime, food particles, including waterborne bacteria and algae, are trapped by the sieve-like collar of the choanocytes, slide down into the body of the cell, are ingested by phagocytosis, and become encased in a food vacuole. Lastly, choanocytes will differentiate into sperm for sexual reproduction, where they will become dislodged from the mesohyl and leave the sponge with expelled water through the osculum. |
SciQ | SciQ-3619 | neuroscience, cardiology, action-potential
Title: Do nerve cells cause action potential in cardiac muscle? I think the answer is no, but I am not 100% sure.
If it was yes, then the dendrite of the nerve cell should each time receive a stimulus causing Na+ channels to open, when the contraction happen.
Also, then it would mean that outside events could alter the function of hearth, which would be dangerous.
The heart has a special excitatory system and a contractile system - Sinoatrial node and Pacemaker cells, which control the action potentials in different portions of the heart.
So heart and primarily myocardium i.e. cardiac muscle can depolarise without any external influence with a slow, positive increase in voltage across the cell's membrane.
Do nerve cells cause action potential in cardiac muscle? The vagus nerve controls heart rate. This is the best example of a direct nerve action potential impacting cardiac muscle, although one could argue the adrenaline system to be an indirect mechanism.
The vagus nerve is part of the parasympathetic system, it acts to decrease heart rate. Resting heart rate is maintained by permanent vagal stimulation/tone by the release of acetylcholine.
The following is multiple choice question (with options) to answer.
What involuntary muscle is found only in the heart? | [
"respiratory muscle",
"digestive muscle",
"cardiac muscle",
"physiological muscle"
] | C | Cardiac muscle is also an involuntary muscle, found only in the heart. The cardiac muscle fibers all contract together, generating enough force to push blood throughout the body. What would happen if this muscle was under conscious or voluntary control?. |
SciQ | SciQ-3620 | geology
Title: Where do riverbed stones come from? Have they always been here since the river was formed? Are some newer than others? Riverbed 'stones' - I assume you mean things like pebbles, boulders, etc. are pieces of rock that have weathered out and been deposited in the river. Some come from rock that is very close to where they are located and some have been transported from very far away. In general (and it is a very broad generalization) the rounder the stone, the longer it has been in the river and the more likely it is to have come from far away. Of course that depends on the hardness of the rock, and other factors, too.
Some rocks are newer than others. Some have been formed quite recently and some are billions of years old.
The following is multiple choice question (with options) to answer.
Most sedimentary rocks form from what? | [
"erosion",
"sediments",
"glaciers",
"volcanic activity"
] | B | Most sedimentary rocks form from sediments. The sediments must be packed together to form a rock. Sedimentary rocks also form as minerals precipitate from saline water. Sedimentary rock formation is described in the next concept. |
SciQ | SciQ-3621 | human-biology, human-anatomy
Title: Difference between the spinal cord and vertebrae column What is the difference between the spinal cord and the vertebrae column, they both run through from the head to the abdomen. Does any one have any idea. The vertebral column is a bony, segmented structure that supports the torso/head and thorax. The spinal cord is a bundle of nerves that runs inside the structure of the vertebral column. So - they run together, but are completely separate.
The following is multiple choice question (with options) to answer.
What system serves as the relay between the cns and the internal organs? | [
"central nervous system",
"cellular nervous system",
"limbic nervous system",
"autonomic nervous system"
] | D | The autonomic nervous system serves as the relay between the CNS and the internal organs. It controls the lungs, the heart, smooth muscle, and exocrine and endocrine glands. The autonomic nervous system controls these organs largely without conscious control; it can continuously monitor the conditions of these different systems and implement changes as needed. Signaling to the target tissue usually involves two synapses: a preganglionic neuron (originating in the CNS) synapses to a neuron in a ganglion that, in turn, synapses on the target organ, as illustrated in Figure 35.26. There are two divisions of the autonomic nervous system that often have opposing effects: the sympathetic nervous system and the parasympathetic nervous system. Sympathetic Nervous System The sympathetic nervous system is responsible for the “fight or flight” response that occurs when an animal encounters a dangerous situation. One way to remember this is to think of the surprise a person feels when encountering a snake (“snake” and “sympathetic” both begin with “s”). Examples of functions controlled by the sympathetic nervous system include an accelerated heart rate and inhibited digestion. These functions help prepare an organism’s body for the physical strain required to escape a potentially dangerous situation or to fend off a predator. |
SciQ | SciQ-3622 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
When pumping blood, the hearts of animals with very long necks must overcome what force? | [
"gravity",
"erosion",
"evolution",
"friction"
] | A | |
SciQ | SciQ-3623 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
The seasonal movements of animals from one area to another is referred to as? | [
"mitigation",
"hybernation",
"echolocation",
"migration"
] | D | Migration refers to seasonal movements of animals from one area to another. Migrants typically travel long distances, and travel the same paths each seasonal cycle. Usually, the migrants move to another area in order to find food or mates. Many birds, fish, and insects migrate. Mammals such as whales and caribou migrate as well. Figure below shows the migration route of a bird called a godwit. Another example of a behavior with a yearly cycle is hibernation. Hibernation is a state in which an animal’s body processes are slower than usual, and its body temperature falls. An animal uses less energy than usual during hibernation. This helps the animal survive during a time of year when food is scarce. Hibernation may last for weeks or months. Animals that hibernate include species of bats, squirrels, and snakes. Most people think that bears hibernate. In fact, bears do not go into true hibernation. In the winter, they go into a deep sleep. However, their body processes do not slow down very much. Their body temperature also remains about the same as usual. Bears can be awakened easily from their winter sleep. |
SciQ | SciQ-3624 | human-anatomy
Atraumatic dislocation.
This occurs when the shoulder dislocates with minimal force such as reaching up for an object or turning over in bed. Usually it will 'pop' back in itself or with a little help. Normally this type of dislocation does not need reducing in A&E. It can occur regularly throughout the day and will be associated with certain positions the arm is placed into. This type of dislocation is associated with people that have 'lax' joints, for example people who hyper-extend their knees and elbows and can get the palms of both hands onto the floor with ease. This joint laxity is normal for these people and the onset of dislocation can be associated with a change in how the muscles around the shoulder are interacting with each other or a change in posture/ position of the arm. This can produce an imbalance in the control of the joint. Referral for appropriate physiotherapy is the initial form of management. The physiotherapist should look at the way in which the muscles and shoulder joint is moving and posture aiming to restore the balance. Treatment can 'cure' the problem as long as the exercises and advice is continued, but in some cases there is only minimal or nil benefit. At this point surgical intervention is indicated.
Positional Non-traumatic dislocations.
This group of people can dislocate their shoulders without any form or history of trauma. Some may have started out dislocating their shoulder as a party trick; others may have always had shoulders that just 'fall' out of joint. This type of dislocation is usually painless and can be put back in easily. Both shoulders are typically involved. The cause of this type of dislocation is usually a result of what we call 'abnormal muscle patterning' which means the strong muscles around the shoulder joint are not working in the correct order causing them to pull the shoulder out of joint with active movement in the particular direction such as lifting the arm forward above the head or out to the side and above the head. The main treatment for this is physiotherapy that looks at re-sequencing the muscles in order to prevent further dislocations. Occasionaly surgery in the form of thermal capsular shrinkage or plication may be neccessary.
The following is multiple choice question (with options) to answer.
Falling onto what joint can fracture the distal humerus? | [
"thumb",
"Foot",
"knee",
"elbow"
] | D | Figure 8.11 Fractures of the Humerus and Radius Falls or direct blows can result in fractures of the surgical neck or shaft of the humerus. Falls onto the elbow can fracture the distal humerus. A Colles fracture of the distal radius is the most common forearm fracture. |
SciQ | SciQ-3625 | physiology, nutrition, organic-chemistry
Title: How is it known that there are only three macronutrients: proteins carbohydrates and lipids? It is stated here that in human nutrition, micronutrients are nutrients required generally in less than 100 mg daily quantities whereas macronutrients are required in gram quantities. It is widely stated that our macronutrients are carbohydrates, lipids, and proteins. How was it shown that these are the human macronutrients and that we don't have other macronutrients?
One answer to this similar question on Quora suggests that ethanol or ketones could be considered macronutrients. Ethanol is mentioned in this article, though ketones are not. Other sources I saw didn't clarify. Summary
The question is based on the misconception that the term “macronutrient” originated as a scientific definition, to which entities satisfying this definition were assigned. In fact it was a default term used as a distinction from compounds falling into the earlier category, “micronutrient”, and was used initially to encompass the three specific classes of food that had been established to be sources of energy through decades of nutritional research. Hence there was no question of whether there “should” be more macronutrients. The term is not a scientific definition, and today is used in different ways so that anyone using the term needs to clarify what it should be taken to mean in that particular context.
Food Energy and the history of Nutrition
Scientific studies of nutrition, dating the late 18th century, were initially concerned with chemical structure, metabolic fate and energy produced by different foods, and this is described in a short readable article by Ned Stafford in Nature (2010) 468, S16–17.
By the end of the 19th century protein, fat and carbohydrate had been established as the chemical fuels that supplied energy from the diet, and the energy values (in terms of the, now obsolete, calorie) had been established by Atwood, using his respiration calorimeter.
Micronutrients
The following is multiple choice question (with options) to answer.
What term is used to describe the energy reserve carbohydrate of animals? | [
"lactose",
"glycogen",
"fructose",
"sucrose"
] | B | Glycogen Glycogen is the energy reserve carbohydrate of animals. Practically all mammalian cells contain some stored carbohydrates in the form of glycogen, but it is especially abundant in the liver (4%–8% by weight of tissue) and in skeletal muscle cells (0.5%–1.0%). Like starch in plants, glycogen is found as granules in liver and muscle cells. When fasting, Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-3626 | electromagnetism, electric-current, torque
Title: How does galvanometer measure more current than is passing through it? My textbook clearly states:
after putting a shunt in parallel to it, a galvanometer becomes an ammeter.
The diagram is quite similar to this:
source
This is fine. I have problem with this:
Now the same acale of the galvanometer which was recording the maximum current $I_g$ before conversion into ammeter will record maximum current I after conversion into ammeter. It means each division of scale in ammeter will be showing higher current than that of galvanometer.
I don't understand how can galvanometer measure current which is not even passing through it? I know we can calculate I from Ig as:
$I_g = I \times S \div (G+S)$
So if we know Ig (which galvanometer is measuring) we can find I. But how does that mean that galvanometer's scale changes and it starts measuring the current which is not even paasing through it? Galvanometer still shows maximum deflection when maximum current is passing through it. But out of the total current in the circuit only some of it goes towards galvanometer and rest goes to shunt. So the actual current in the circuit is more than which is passing through galvanometer.
But the galvanometer is calibrated accordingly that it will show the reading of $I$ and not $I_g$.
Galvanometer still shows deflection proportional to $I_g$ but the reading is different as the calibration is different. Hence the reading is I though current in galvanometer though the current through it is Ig because the 1 divisions or marking on ammeter is actually different than what actual current is passing through it.
So though $I_g$ is current it shows $I_g+I_s$ as it is calibrated as such.
So suppose there are 10 divisions then Ig is maximum current so when Ig/10 current passes it shows deflection of one division but the galvanometer is calibrated as 1 division =I/10. That maximum current measured by ammeter is I.
The following is multiple choice question (with options) to answer.
What is used to measure current through a resistor? | [
"spectrographs",
"ammeters",
"thermometers",
"microscopes"
] | B | Ammeters measure the current through a resistor. |
SciQ | SciQ-3627 | ions, ionic-compounds
Title: Why do samples of ionic compounds break into pieces, but the pieces do not combine into larger samples again? A distinct property of ionic compounds is that they are brittle. We are taught this is due to the fact that when force is applied to the lattice, ions are shifted, resulting in positive ions repelling positive ions and negative ions repelling negative ions. As a result, the lattice shatters. Hence ionic compounds are brittle. Makes logical sense to me.
However, using similar intuition, could we not just as well take the shattered pieces and hold them together again. At some point, we should get oppositely charged ions aligning causing the shattered pieces to come together again. Obviously when we hold, table salt together, they don't come back together. So what is fundamentally wrong with my intuition here? Your intuition is not wrong... but the atoms near the surface have to be free to move or exactly aligned, and must not covered by an adhered layer of air.
For example, by dissolving a salt in water and letting the water evaporate, you can watch crystals grow, as atoms (well, ions) find their place in the lattice. Read Crystals and Crystal Growing by Holden and Morrison, for example, download a free classic, such as Tutton's Crystals, or look online, such as Science Notes, How to Grow a Crystal.
Of course, there are crystals of metals and non-ionic compounds, too. Consider that only mildly-ionic water vapor condenses to make snowflake crystals, investigated by Bentley.
Simply holding pieces in your hand and hoping the crystal structure to align ignores theses issues:
The surface of the crystals would have to be atomically smooth, not jagged. Examine the surface of even a carefully cleaved crystal under an atomic force microscope and you'll find few smooth areas. The jagged peaks and valleys prevent the surfaces from meeting except at a few points.
As soon as a crystal is cleaved in air, the surface is covered with an adhered film. Germer states in The Study of Crystal Surfaces, "One of the most significant facts about real surfaces is that they quickly become dirty; a freshly cleaved crystal
soon adsorbs foreign atoms on its surface." The effect is like using waxed paper to keep dough from sticking to surfaces.
However, given smooth surfaces, they do stick together in the process of cold welding.
The following is multiple choice question (with options) to answer.
When struck, how are the rigid crystals of ionic compounds likely to react? | [
"break",
"bend",
"shrink",
"grow"
] | A | The rigid crystals of ionic compounds are brittle. They are more likely to break than bend when struck. As a result, ionic crystals tend to shatter easily. Try striking salt crystals with a hammer and you’ll find that they readily break into smaller pieces. You can learn more about the properties of ionic compounds by watching the video at this URL:. |
SciQ | SciQ-3628 | optics, visible-light, condensed-matter, superconductivity, quantum-optics
Title: Optical equivalent of a superconductor Is there some material state that can propagate light indefinitely without dissipation or absorption, like superconductors are able to transmit current indefinitely?
If not, then the question is, why not? would some fundamental principle being violated in such a material? As Claudius suggests, vacuum does not absorb. But that is not a material.
You can have light that travels through a material without absorption; that happens in nonlinear optics with self-induced transparency. The full theory behind that is rather involved and you need really high intensities for that. The basic picture is that the front of the light pulse is absorbed and the back of the pulse stimulates emission from all the excited photons. Thus, the back gets to the front and is absorbed and the whole cycle repeats.
The following is multiple choice question (with options) to answer.
What type of matter transmits light without scattering it? | [
"transparent",
"reflective",
"smooth",
"opaque"
] | A | Transparent matter is matter that transmits light without scattering it. Examples of transparent matter include air, pure water, and clear glass. You can see clearly through transparent objects, such as the top panes of the window below , because just about all of the light that strikes them passes through to the other side. |
SciQ | SciQ-3629 | neuroscience, neuroanatomy, neurology
Title: Is it possible to temporarily paralyze someone through the use of electric signals or focused ultrasound? I've been reading about how it is possible to send signals to the brain using focused ultrasound or electrical impulses. It is possible to make someone see a certain shape or color by stimulating different areas of the brain. I was wondering whether or not it would be possible to temporarily shut off a person's motor functions by for example, sending signals to the cerebellum or perhaps intercepting them before they can travel down the spinal chord. With in-depth study and research, it would be possible on 1 person. However, it's unlikely that this type of technology could ever be weaponized.
Nerves and neural networks are particularly known for having unique calibrations per individual. Even if you can decipher every neural communication protocol on a test subject, the signal protocol would be at least slightly different on others, even for crude movement control.
Mind control would be several orders of magnitude harder - each person's brain is different.
Most neurons communicate through neurotransmitters rather than electricity, completely ignoring your control scheme.
Even if none of these barriers existed, people could always block them using "tinfoil hats".
The following is multiple choice question (with options) to answer.
What is the term for the unconscious movements controlled by the somatic nervous system? | [
"mechanisms",
"reflexes",
"tremors",
"senses"
] | B | The somatic nervous system also controls some unconscious movements, called reflexes. A reflex is a very rapid motor response that is not directed by the brain. In a reflex, nerve impulses travel to and from the spinal cord in a reflex arc , like the one in Figure below . In this example, the person jerks his hand away from the flame without any conscious thought. It happens unconsciously because the nerve impulses bypass the brain. |
SciQ | SciQ-3630 | biochemistry, biophysics, bioenergetics
Title: Are there known life forms that are able to transform mechanical energy into chemical energy? Are there known life forms that are able to transform mechanical energy into chemical energy?
This question asks a similar subject, but more specific and has no answers.
The background of this question are thoughts about hypothetical life on tidally locked exoplanets of red dwarf stars, where light for photosynthesis is scarce but mechanical energy (storms and/or water currents) aplenty. There are no known life forms that use mechanical energy as a primary form of metabolic energy (i.e., for generic cellular functions). Many life forms are sensitive to mechanical disruption in some way, so they do utilize mechanical energy, but in a very limited fashion (@David's answer touches on this), and of course many organisms have life cycles that somehow depend on mechanical transportation (seed/spore dispersal, traveling on the wind or ocean currents, etc).
I think the main physical problem is that mechanical energy just isn't available to biological cells in a form that can be converted to substantial chemical energy. They are small, and tend to have other great benefits for being small.
To use an ocean wave as an example, there is very little or no perceptible movement for a cell in that wave, besides an apparent increase and decrease in the force of gravity. The top and bottom of the cell are moving together with the flow of water, so there is no differential to operate on.
An E. coli weighs about 1 picogram. If it could capture all of the energy from falling from 1km in the air on earth, assuming no uncaptured aerodynamic drag, that would be about 10-11 joules.
If there are ~3000 kJ/mol of energy available from burning glucose, that means about 5 × 10-21 joules per molecule of glucose, so about 20 billion glucose molecules, which sounds like a lot but it is only 1 femtogram, 0.1% the weight of the cell.
The following is multiple choice question (with options) to answer.
What organism captures light energy and converts it to chemical energy inside its cell? | [
"plants",
"insects",
"phototrophs",
"autotrophs"
] | C | Because glaciers move, they have characteristic features like crevasses and bergshrunds. |
SciQ | SciQ-3631 | phase-transition, freezing, ice
Title: Freezing point depression - cooling my drink with the same method as salt on a highway? I understand that adding/sprinkling, say NaCl, on a highway depresses the freezing point by making any moisture on the road harder to freeze as the NaCl molecules get in the way of phase transition. So now we need lower temperatures to freeze the moisture on the road.
However, why can I cool my drink "better" by placing it in a salt + ice bath instead of just an ice bath? It would seem that a salt + ice bath only keeps the water from freezing or in other words, the ice from melting for longer duration of time. Where does the lowering of temperature come into this picture?
I am not able to connect these two phenomenon although people tell me they are the same.
Links to what I have already seen:
http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-melts-ice.shtml
http://revision3.com/forum/showthread.php?t=34351
I need someone to rephrase something and I cant put my finger on it.
Edit:
I was thinking more about it and here is what I can further add to my question:
Sprinkling salt on the highway PREVENTS water to ice transition by intereference due to NaCl molecules. It is actually preventing the liquid-solid transition and it would seem to people that NaCl is melting the ice.
When I place my drink in a ice + salt (NaCl) mix, the NaCl molecules dissociate into Na+ and Cl- ions into the water and this is an endothermic reaction where the NaCl molecules remove heat from the water molecules decreasing the temperature of water molecules and converting them to ice. I am assuming that the NaCl molecules strip the ice of heat as well further decreasing their temperature.
The following is multiple choice question (with options) to answer.
By applying salt to an icy road, the melting point of the ice is what? | [
"decreased",
"increased",
"compounded",
"concentrated"
] | A | Colligative properties have practical applications, such as the salting of roads in cold-weather climates. By applying salt to an icy road, the melting point of the ice is decreased, and the ice will melt more quickly, making driving safer. Sodium chloride (NaCl) and either calcium chloride (CaCl 2 ) or magnesium chloride (MgCl 2 ) are used most frequently, either alone or in a mixture. Sodium chloride is the least expensive option, but is less effective because it only dissociates into two ions instead of three. |
SciQ | SciQ-3632 | human-genetics
Title: In our 23 chromosome pairs, do the 2 members of the pair have distinct or virtually identical sequences? I understand that we have 46 DNA molecules in the nucleus of our cells, arranged in 23 pairs: 22 autosomal and 1 sex chromosome pairs.
I have read in different sources that the pairs contain nearly identical members, excluding any mutations. I have also read that the pairs contain 1 member we inherited from our mothers and 1 we inherited from our fathers, which are different due to inheritance.
This seems contradictory, given that genealogical companies match up on the differences on these chromosomes.
My understanding was that meiosis creates sperm and egg cells that each carry 23 chromosomes - they are haploids. During the first steps of meiosis that creates the reproductive cells we have a combining of the parent's chromosome pair from their parents to create 4 daughter cells, each independently viable, where the recombination of the chromosome pair has occurred at somewhat predictable spots (for you perhaps :-) ) and that these spots can be related to genes. It is this step that give us our genetic variation between siblings for example. A new person's DNA is partially formed from any one of these highly varied daughter cell possibilities.
Fertilization combines the reproductive cells to produce the 46 chromosome zygote with is again diploid.
I think this understanding supports the second interpretation that our chromosome pairs are not 2 nearly identical DNA molecules but are distinct.
Have I got this right? Is there a missing process or a misunderstanding in my interpretation? Homologous chromosomes (those that are paired up), excluding the sex pair are almost identical in size, shape and genes (members as you called them) present in them.
Genes determine traits and each homologous chromosome controls the same traits. The level of identity of a gene inside a population varies between genes. There are very conserved ones that do not change even between humans and yeast and others that vary alot event inside a species. This changes can be small in sequence length, a simple base (letter) swap or one deletion, and have a huge effect on the traits. This is how chimps and humans are very different but share 98.6% of their genome and humans are very similar and share 99.9% of their genome.
In summary, on the bigger scale homologous chromosomes are very similar (size, shape, traits inside), on the smaller scale homologous chromosomes have small changes that affect greatly.
The following is multiple choice question (with options) to answer.
How many pairs of chromosomes do human have ? | [
"19 pairs",
"31 pairs",
"23 pairs",
"12 pairs"
] | C | Human Genome, Chromosomes, and Genes. Each chromosome of the human genome contains many genes as well as noncoding intergenic (between genes) regions. Each pair of chromosomes is shown here in a different color. Notice that there are 23 pairs of chromosomes. |
SciQ | SciQ-3633 | zoology, species-identification, marine-biology, invertebrates
Title: Species identification - greenish blue ocean worm (nudibranch?) in Perhentian Islands, Malaysia We found this on a beach at the Perhentian Islands, Malaysia in March, 2016 and cannot identify it. It's some sort of worm-type creature with many legs and bluish back about 15cm long. The legs undulated along the body as it swam.
back:
belly side: It's hard to identify from the photos provided, but I think it is Chloeia flava (a species of polycaete worm, within the phylum Annelida), also known in English as the "Golden Fireworm".
The size is roughly similar to what you describe (they are typically about 7-10 cm long). The individual you observed looks like it lives in sandy bottom environments (not a typical environment for a nudibranch), and this worm does also. It is commonly found all across the warmer Indo-Pacific as well, and looks like the individual observed in your photo.
If it is not this species, I think it is another species of the same family, Amphinomidae.
The following is multiple choice question (with options) to answer.
Where do polychaetes live? | [
"lakes",
"ocean floor",
"the tundra",
"great plains"
] | B | Polychaetes live on the ocean floor. They may be sedentary filter feeders, active predators, or scavengers. Active species crawl along the ocean floor in search of food. |
SciQ | SciQ-3634 | genetics, homework, human-genetics
Title: What are sex linked traits? Which of the two definitions of sex-linked trait is correct?
Traits controlled by genes present on the non-homologous region of sex chromosomes are called sex-linked traits.
Bodily traits controlled by genes present on the non-homologous regions of sex chromosomes are called sex-linked traits. Here by bodily traits I mean traits that are not involved with sex of an organism.
I read the first definition in the book Competition Science Visionand also from Instant notes genetics (page 163).
The following is an excerpt from the latter
Sex linkage is not displayed by genes which map to a small segment of X chromosome, the pseudoautosomal region, the part of X chromosome that pairs with Y chromosome in meiosis.
The second definition is made up but sounds potentially intuitive to me. The first definition is correct.
A sex-linked trait is a trait affected by a locus on a sex chromosome.
If you google sex-linked trait, you will find this same definition (not the exact same words) over and over again.
The definition of sex-linked trait is NOT restricted to traits that are not unrelated to primary or secondary sexual organs. Any phenotypic trait can be sex-linked as long as the causal locus is on a sexual chromosome.
The following is multiple choice question (with options) to answer.
What term describes a gene or sequence on a chromosome that co-segregates (shows genetic linkage) with a specific trait? | [
"autosomal",
"nucleic acid chain",
"genetic marker",
"analogous effect"
] | C | 17.2 | Mapping Genomes By the end of this section, you will be able to: • Define genomics • Describe genetic and physical maps • Describe genomic mapping methods Genomics is the study of entire genomes, including the complete set of genes, their nucleotide sequence and organization, and their interactions within a species and with other species. Genome mapping is the process of finding the locations of genes on each chromosome. The maps created by genome mapping are comparable to the maps that we use to navigate streets. A genetic map is an illustration that lists genes and their location on a chromosome. Genetic maps provide the big picture (similar to a map of interstate highways) and use genetic markers (similar to landmarks). A genetic marker is a gene or sequence on a chromosome that co-segregates (shows genetic linkage) with a specific trait. Early geneticists called this linkage analysis. Physical maps present the intimate details of smaller regions of the chromosomes (similar to a detailed road map). A physical map is a representation of the physical distance, in nucleotides, between genes or genetic markers. Both genetic linkage maps and physical maps are required to build a complete picture of the genome. Having a complete map of the genome makes it easier for researchers to study individual genes. Human genome maps help researchers in their efforts to identify human disease-causing genes related to illnesses like cancer, heart disease, and cystic fibrosis. Genome mapping can be used in a variety of other applications, such as using live microbes to clean up pollutants or even prevent pollution. Research involving plant genome mapping may lead to producing higher crop yields or developing plants that better adapt to climate change. |
SciQ | SciQ-3635 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
What type of blood vessels carry blood away from the heart? | [
"Viens",
"arteries",
"tubes",
"Heart"
] | B | Arteries are muscular blood vessels that carry blood away from the heart. They have thick walls that can withstand the pressure of blood being pumped by the heart. Arteries generally carry oxygen-rich blood. The largest artery is the aorta, which receives blood directly from the heart. |
SciQ | SciQ-3636 | desert
Title: When was the first not-icy desert formed? For how long have deserts existed and which one would be the first to be created? I'm talking about arid, dry deserts, not the Antarctic or Arctic or any other icy deserts. Deserts have existed since at least the Permian period (299-251 million years ago) when the world's continents had combined into the Pangaea supercontinent. Stretching from pole to pole, this land mass was large enough that portions of its interior received little or no precipitation, according the University of California Museum of Paleontology.
Pangaea broke into smaller land masses which were moved across the surface by tectonic forces, a process that both changed global climate patterns and the climate those continents were exposed to. As a result, current desert regimes date back to no more than 65.5 million years, according to this Encyclopedia Britannica article:
The desert environments of the present are, in geologic terms,
relatively recent in origin. They represent the most extreme result of
the progressive cooling and consequent aridification of global
climates during the Cenozoic Era (65.5 million years ago to the
present), which also led to the development of savannas and scrublands
in the less arid regions near the tropical and temperate margins of
the developing deserts. It has been suggested that many typical modern
desert plant families, particularly those with an Asian centre of
diversity such as the chenopod and tamarisk families, first appeared
in the Miocene (23 to 5.3 million years ago), evolving in the salty,
drying environment of the disappearing Tethys Sea along what is now
the Mediterranean–Central Asian axis.
Which would put the oldest of "modern" desert somewhere in the region of what later became North Africa or South Asia.
The following is multiple choice question (with options) to answer.
How many millions of years ago did pangaea begin breaking apart? | [
"250",
"600",
"500",
"400"
] | A | Pangaea has been breaking apart since about 250 million years ago. Divergent plate boundaries formed within the continents to cause them to rift apart. The continents are still moving apart. The Pacific is shrinking as the Atlantic is growing. The Appalachians ( Figure below ) are now on a passive margin. The mighty mountains have weathered and eroded to what they are today. |
SciQ | SciQ-3637 | evolution, speciation
Lastly, I consider whether primary and secondary sympatric speciation represent a mechanistic dichotomy, I suggest that primary and secondary contact can leave a similar genomic signature, when speciation is driven by tightly clustered or large effect loci. Arguably, the advent of affordable population genomic studies should place less focus on whether study systems result from primary or secondary contact and instead focus on the mechanistic aspects of the genomic architecture and making progress in identifying the conditions and processes under which natural and sexual selection can drive speciation, without extrinsic barriers to gene flow. TLDR
Sympatric speciation and allopatric speciation with later migration into the same habitat were historically diffucult to distinguish without looking at palaeo-biological data. The paper argues that while palaeo-genetics has made this easier, it is still difficult to distinguish pure sympatric speciation (which it calls primary) and sympatric speciation with a geneflow from an geographically separated (allopatrically speciated?) subpopulation (which it terms "secondary sympatric speciation" or "speciation with secondary gene flow", "...with secondary contact" etc.).
Speciation
Speciation is the divergence of one species (with one gene pool) into two different species (with different gene pools). It is obvious that this will happen if subpolulations are geographically separated and continue to adapt to their local conditions (allopatric speciation).
However, Mayr suggested (back in the 1940s) that there is another type of speciation that happens while the speciating populations share a habitat, and, consequently, while gene flow between these subpopulations is maintained until the speciation process is complete. This requires strong selection pressure towards two different ecological niches each with their associated adaptations.
Empirical examples have been discussed and called into question again. One cool and frequently discussed example is that of the apple maggot in North America that has developed from the hawthorn maggot after the introduction of apples in North America.
Debate
The following is multiple choice question (with options) to answer.
Continental drift also promotes what speciation? | [
"macroevolution",
"obligate",
"mutualistic",
"allopatric"
] | D | |
SciQ | SciQ-3638 | python, algorithm, programming-challenge, python-3.x, time-limit-exceeded
pos+=1
proteins = mutated
print(proteins) I encourage you to abandon your present approach.
Instead, try expressing each of your A/B/C/D proteins as integer numbers. Then express those integer numbers in binary form, and see if you can determine the operation(s) underlying the very, very regular pattern visible in the table given in the problem.
If you transcode the "protein sequences" to a series of 2-bit numbers, I believe you can profitably perform your mutations at a high rate of speed.
The following is multiple choice question (with options) to answer.
Which kind of mutations have the most dramatic effect on proteins? | [
"arbitrary mutations",
"sight mutations",
"nonsense mutations",
"cancerous mutations"
] | C | These mutations may result in a protein with the same function, with altered function, or with no function. Silent mutations , as they code for the same amino acid, will have no altered effect on the protein. Missense mutations may have a minor effect or a dramatic effect on the protein. Nonsense mutations usually have the most dramatic effet. Depending on the position of the premature stop codon, nonsense mutations may result in an unstable mRNA that cannot be translated, or in a truncated mRNA and a much "smaller" protein without any significant activity. |
SciQ | SciQ-3639 | java, role-playing-game
//This is where the critter attack goes
/*
* d100();
*
* if (d100Result >= 0 && d100Result <= 20) {
*
* } else if (d100Result >= 21 && d100Result <= 40) {
*
* } else if (d100Result >= 41 && d100Result <= 100) {
*
* } else {
* System.out.println(there is an error here!");
* }
*
*/
d3();
switch (d3Result) {
case 1:
critterOffensive = true;
critterDefensive = false;
critterEvasive = false;
System.out.println("The " + critterName + " charges!");
System.out.println("Your children and the " + critterName + " are evenly matched!");
break;
case 2:
critterDefensive = true;
critterOffensive = false;
critterEvasive = false;
System.out.println("The " + critterName + " protects itself!");
System.out.println("Your children crush the " + critterName + "'s defenses!");
System.out.println("The " + critterName + " takes damage!");
critterHealth -= 1 * missionWorkerDrones + (missionWarriorDrones * 2);
break;
case 3:
critterEvasive = true;
critterDefensive = false;
critterOffensive = false;
System.out.println("The " + critterName + " moves quickly!");
System.out.println("Your children are outflanked by the " + critterName + "!");
System.out.println("One of your drones falls from it's wounds!");
d2();
switch (d2Result) {
case 1:
if (missionWarriorDrones > 0) {
killWarrior();
} else if (missionWarriorDrones <= 0) {
killWorker();
}
break;
case 2:
The following is multiple choice question (with options) to answer.
When skunks are in danger what do they give off? | [
"warning howls",
"sweet odor",
"ejected quills",
"foul smell"
] | D | |
SciQ | SciQ-3640 | genetics, botany, seeds
Title: What DNA does a self-fertile plant's seedling have? Some plants are said to be self-fertile. An example is Prunus tomentosa.
Assuming that no cross-pollination happened with other plants, if a self-fertile plant such as prunus tomentosa produces a seedling, what DNA will the seedling have? Is the seedling's DNA an exact copy of the parent plant's DNA, or do the genes get rearranged? Selfing (aka self-fertilizing) differs from cloning. When selfing occurs, the offspring is not an exact copy of the parent. When cloning occurs, the offspring is an exact copy (except for a few mutations) of the parent.
Selfing implies that an individual will produce two gametes (typically a spermatozoid and an ovule but that might be a bit more complicated) and these two gametes are fusing to give the zygote (egg or offspring if you prefer).
As a consequence, when selfing, meiosis is occurring (and therefore segregation and recombination) so that the offspring is not an exact clone of the parent but rather some kind of a rearrangement of the parent genome (with a few mutations of course).
The following is multiple choice question (with options) to answer.
What kind of reproduction produces genetically identical organisms or clones? | [
"asexual",
"Sexual",
"Prophase I",
"Meiosis"
] | A | Introduction Animal reproduction is necessary for the survival of a species. In the animal kingdom, there are innumerable ways that species reproduce. Asexual reproduction produces genetically identical organisms (clones), whereas in sexual reproduction, the genetic material of two individuals combines to produce offspring that are genetically different from their parents. During sexual reproduction the male gamete (sperm) may be placed inside the female’s body for internal fertilization, or the sperm and eggs may be released into the environment for external fertilization. Seahorses, like the one shown in Figure. |
SciQ | SciQ-3641 | ocean, thermodynamics
Your friend is half right, and half wrong. Air has a bit over 1/4th the heat capacity compared to water and it's about 800 times less dense, so he's correct, but it's not that simple.
Sunlight - somewhat counter-intuitively, isn't great at warming oceans because the photons from sunlight are energetic enough to evaporate water molecules into gas molecules. Oceans have low albedo which means they absorb most of the energy from the sunlight, but much of that heat is lost in evaporation by visible light photons. While that has nothing to do with your question, it's worth pointing out that sunlight isn't as good at warming oceans as one might think. (If anyone has one of those solar mirror ovens, I'd be curious to see how well they work on pure water . . . just out of curiosity, evaporation loss vs rate of warming).
The back-radiation from the atmosphere is comparatively much less total solar energy, but oceans are good at absorbing and storing thermal back-radiation reflected back off the greenhouse gas rich atmosphere into the ocean. This is a tiny amount of the total heat Earth gets from sunlight, and the increase of this radiation due to greenhouse gas is a fraction of one percent of solar energy, but it adds up.
One way to explain this is that 85 degree air will warm 80 degree water. That's a thermodynamic law. It just takes a while and because the heat capacity and density of water is much greater, it takes about 4 liters of air to give 1 degree back to warm 1 cc of water 1 degree. But despite the inefficiency, warmer air still transfers heat into colder water. It takes many decades, perhaps centuries, for the oceans to catch up to the warming air, but air, however inefficiently, does warm the oceans.
The following is multiple choice question (with options) to answer.
Oceans help control global warming by absorbing what? | [
"methane",
"hydrogen",
"carbon dioxide",
"ozone"
] | C | Ocean water also absorbs gases from the atmosphere. The most important are oxygen and carbon dioxide. Oxygen is needed by living things in the oceans. Much of the carbon dioxide sinks to the bottom of the seas. Carbon dioxide is a major cause of global warming. By absorbing carbon dioxide, the oceans help control global warming. At least as long as the carbon dioxide stays in the seas. |
SciQ | SciQ-3642 | solutions
Title: Binary diagram and two phase region I know that to find the composition in a two phase region of a binary diagram we have to draw the isotherm and to look at the intersection with phase boundaries.
But why? Is there a demonstration? I will assume that the y-axis in your graph is temperature, and that the pressure of the system is fixed.
Consider the physical system: a mixture of two species in two phases is at equilibrium. Gibbs' phase rule tells us that we have two degrees of freedom, which can be chosen from the set $\{P, T, X_B^{liq}, X_B^\text{solid}\}$. By fixing $P$ (first degree of freedom) and letting $T$ (second degree of freedom) vary over a prescribed range, we produce the functions $X_B^{liq} = X_B^{liq}(T)$ and $X_B^\text{solid} = X_B^\text{solid}(T)$, and this is exactly what is represented by a phase diagram.
The following is multiple choice question (with options) to answer.
A phase diagram plots temperature and what else? | [
"pressure",
"power",
"movement",
"friction"
] | A | Both temperature and pressure have an effect on the phase in which a given substance exists. A plot of temperature vs. pressure that indicates the states of matter present at each point is known as a phase diagram . Figure below shows the phase diagram for water. |
SciQ | SciQ-3643 | growth-media
Title: Is it essential to add cholesterol to agar or liquid culture for C. elegans? In preparing agar plates with NGM, and also liquid cultures for growing c elegans, how essential is the addition of cholesterol and heavy metals? I have prepared both. I can't notice any obvious difference and I hate having to add all these supplements.
I'm using yeast extract and peptone as the primary components of the base.
Isn't this just supposed to be a moist semi-soft substrate for them to crawl around, their nutrients come from the bacteria they eat. C. elegans needs cholesterol, but can't make it. Since bacteria don't make cholesterol either, the food bacteria aren't a source. As explained in the linked paper, lack of cholesterol affects normal development.
The following is multiple choice question (with options) to answer.
What kind of hormones are derived from cholesterol? | [
"steroid",
"germs",
"Antibiotic",
"synthesis"
] | A | 17.2 Hormones Hormones are derived from amino acids or lipids. Amine hormones originate from the amino acids tryptophan or tyrosine. Larger amino acid hormones include peptides and protein hormones. Steroid hormones are derived from cholesterol. Steroid hormones and thyroid hormone are lipid soluble. All other amino acid–derived hormones are water soluble. Hydrophobic hormones are able to diffuse through the membrane and interact with an intracellular receptor. In contrast, hydrophilic hormones must interact with cell membrane receptors. These are typically associated with a G protein, which becomes activated when the hormone binds the receptor. This initiates a signaling cascade that involves a second messenger, such as cyclic adenosine monophosphate (cAMP). Second messenger systems greatly amplify the hormone signal, creating a broader, more efficient, and faster response. Hormones are released upon stimulation that is of either chemical or neural origin. Regulation of hormone release is primarily achieved through negative feedback. Various stimuli may cause the release of hormones, but there are three major types. Humoral stimuli are changes in ion or nutrient levels in the blood. Hormonal stimuli are changes in hormone levels that initiate or inhibit the secretion of another hormone. Finally, a neural stimulus occurs when a nerve impulse prompts the secretion or inhibition of a hormone. |
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