source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-2144 | condensed-matter, crystals
Are the crystals the same if they are grown on glass, different rocks, plastics, metals, …? (For example, whether ZnO forms a pyramidal structure can depend on its growth substrate.)
Does the crystal shape depend on whether you have a single crystal or multiple crystals growing in close proximity (as is common with crystal growing kits)? Growing crystals remove nearby solute which is only slowly replaced by diffusion.
A bunch of neighbouring crystals deplete solutes near their bases and might grow faster at their tips where the concentration is higher. This could, however, be reversed by convection that can occur as the solution near the crystals becomes less dense because the solute molecules are absorbed and because the heat of crystallization warms the liquid. This convection can create a gradient with solute concentration decreasing with height, so now the bottom of the crystals may grow faster.
The following is multiple choice question (with options) to answer.
What does the precise pattern of a crystal depend on? | [
"chance",
"compound",
"mass",
"age"
] | B | A crystal contains a three-dimensional array of alternating positive and negative ions. The precise pattern depends on the compound. A crystal of sodium chloride, shown here, is a collection of alternating sodium and chlorine ions. |
SciQ | SciQ-2145 | neuroscience, neurophysiology, memory, cognition
Title: What are the advantages of forgetting? How forgetting things is helpful for the brain or the human body biologically? This web page
After some moment of being rude, selfish, or weak, either we are able to put it behind us, or the person who suffered at the result of our imperfection moves on. The reason for this is our ability to forget about it. We forget not because we have an imperfect hippocampus (our brain’s memory organ); it's actually an evolved solution. The ability to lose information allows new information to come in that is more relevant, more pertinent to an ongoing reality. Forgetting allows us to update.
and this Huffington post article
According to a study in Nature, our awareness is limited to only three or four objects at any given time. To be able to think at your highest level, you therefore must be very efficient at filtering out all of the background noise: Your racing thoughts, the ringing phone, your neighbor’s barking dog, and the list goes on.
The Nature study found that when participants were asked to “hold in mind” certain objects while ignoring others, there are significant variations in how well each of us can keep irrelevant objects out of our awareness.
The researchers concluded that our memory capacity is therefore not simply about storage space, but rather “how efficiently irrelevant information is excluded from using up vital storage capacity.”
provide some backgrounds. Short answer
It has been shown that loss of long-term memories may enhance the retrieval of others. Short-term working memory is explicitly designed to be volatile and non-lasting. However, there are many other types of memories where memory loss may not be explicitly beneficial, or even outright debilitating such as in the case of Alzheimer's or stroke.
Background
First off all, there are many types of memories, including sensory memory, motor memory, short-term (working) memory, long-term memory, explicit & implicit memory, declarative & procedural memory and so on. Hence, because the question is quite broad, I will focus on long-term memory, short term-memory and sensory memory to discuss that memory loss can be beneficial, neutral, or detrimental.
The following is multiple choice question (with options) to answer.
Learning to get used to something after being exposed to it for a while is associated with what kind of learning? | [
"assimilation",
"habituation",
"dissociation",
"association"
] | B | Habituation is learning to get used to something after being exposed to it for a while. Habituation usually involves getting used to something that is annoying or frightening, but not dangerous. Habituation is one of the simplest ways of learning. It occurs in just about every species of animal. |
SciQ | SciQ-2146 | evolution, zoology, anatomy
Title: Are the transverse septum in sharks and the diaphragm in mammals homologous structures? Are the transverse septum in sharks and the diaphragm in mammals homologous structures?
I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim. A beginning of answer here below, I hope. Please first consider that many structures are involved in the question here, the diaphragm (UBERON:0001103), the diaphragmaticus muscle (UBERON:0036071) and the septum transversum (UBERON:0004161). At Bgee (bgee.org) we aim annotating relations of similarity between anatomical structures, please have a look at our GitHub
https://github.com/BgeeDB/anatomical-similarity-annotations
We already annotated 'diaphragm' as a mammalian structure, not homologous in Amniota (please see https://raw.githubusercontent.com/BgeeDB/anatomical-similarity-annotations/master/release/similarity.tsv). In our next release, you will see the annotation for the 'diaphragmaticus muscle' which is an analog organ in Crocodylians (and Turtles) but not homologous to the mammalian diaphragm either. See here for more details about this new Uberon class:
https://github.com/obophenotype/uberon/issues/1229.
Based on the comments here above, I would say that currently we can argue that there is no evidence for a homologous relationship between the 'septum transversum' in sharks and the mammalian diaphragm. Please note that UBERON:0004161 septum transversum describes the (mammalian) embryonic structure that will give rise to the central tendon of the diaphragm, while here you are talking about a adult structure closer to a 'diaphragmaticus muscle'-like septum, as far as I understand.
But anyway thank you for your interesting question that points out a very exciting and rapidly evolving evo-devo field, as this recent paper also suggests
The following is multiple choice question (with options) to answer.
Is the digestive tract of many sharks longer or shorter than many other vertebrates? | [
"shorter",
"heavier",
"longer",
"narrower"
] | A | |
SciQ | SciQ-2147 | human-biology
Title: Stopping the effect of hormone Many hormones released by endocrine organs travel down in the blood and bind to specific receptors on the target cells. What then breaks that binding of the molecule with the receptor ? ( thus inactivating further stimulation of the target cell ) The binding is reversible typically; part of the potency of a drug is ow well and for how long it binds to its target. There's a natural equilibrium of binding and dissociation. Many drugs, once bound to their cognate receptor, cause a down regulation of their cognate receptor on the target cell. The bound/activated downstream signalling pathways may be inhibited by ubiquitination of the downstream signals themselves or upregulation of antagonists etc. The hormone itself has a half life, which is very important, thus levels naturally decrease and for some hormones this is incredibly rapid. Levels may decrease due to breakdown or excretion. Increase of binding hormones may decrease free hormone thus it's effect also.
The following is multiple choice question (with options) to answer.
In the case of the thyroid hormone pathway, thyroid hormone itself carries out what kind of feedback? | [
"effective",
"negative",
"positive",
"continued"
] | B | |
SciQ | SciQ-2148 | population-genetics, conservation-biology
Where cloning can come in is it can be used to increase the gene pool, sometimes quite substantially. Consider the meta-population of a species, this could be allowed to include all of the wild sub-populations and all captive or managed (semi-captive) populations. For example, there are ~3900 wild tigers in the world, and ~5000 in captivity. Among all of those, only a subset contribute offspring to the next generation of wild animals, reducing the effective population size, and increase rates of inbreeding and genetic drift. For example, often very few males fertilise the females of a population with strong effects on the effective population size. What cloning could be used for (to various levels, depending on the specifics of the method) is to allow other individuals to contribute. For example, by cloning the members of a wild population that were unable to secure mates during a reproductive season (there is often high variance in mating success which reduces effective population), conservation managers can artificially re-inflate the effective population size to more closely resemble the census population size. In other cases, conservation managers may chose to clone particularly viable/fertile individuals that are approaching old age or nearing death, and are therefore at risk of being lost from the population. Conservation programs could use cloning of (semi-)captive individuals and introducing clones from (semi-)captive populations in to wild populations allowing genetic variation to be drawn from the gene pool of (semi-)captives in to the wild populations. Increasing the variance in the gene pool will increase the adaptive potential of the wild population. Another option is to clone wild animals in threatened areas (e.g. where populations are in decline as a result of poaching) and to put the clones in to safer areas such as national parks, or even zoos, to preserve genetic variation while conservation managers try to bring the other issues under control. Effectively this would act a bit like a seed bank.
The following is multiple choice question (with options) to answer.
What increases the size of a population's gene pool? | [
"microbes",
"mutations",
"mass extinction",
"natural selection"
] | B | A gene pool is the complete set of unique alleles in a species or population. Mutations create variation in the gene pool. Populations with a large gene pool are said to be genetically diverse and very robust. They are able to survive intense times of natural selection against certain phenotypes. During these times of selection, individuals with less favorable phenotypes resulting from deleterious alleles (due to mutations) may be selected against and removed from the population. Concurrently, the more favorable mutations that cause beneficial or advantageous phenotypes tend to accumulate in that population, resulting, over time, in evolution. In fact, without any change in the gene pool, without any new alleles added due to new mutations, evolution could not occur. Genetic change is the driving force of evolution. In fact, evolution can be genetically defined as the change allele frequencies over time. |
SciQ | SciQ-2149 | human-anatomy, cardiology
Title: Structure separating the left atrium from the ascending aorta? With reference to the (adult) anatomy of the human heart:
The left atrium (LA) and the proximal part of the ascending aorta (Ao) abut one another, as shown nicely in this image [1]. Is there a name for the wall(s) separating the LA and Ao? And is this a single structure (i.e. septum), or is there a sinus?
[1] http://www.radiologyassistant.nl/data/bin/w440/a5097978b829cd_3-chamber.jpg There isn't any particular structure there: you have the wall of the aorta/adventitia, and if you have an explanted heart there is a space and then the auricle of the left atrium on one side and the right atrium on the other. These would all be contained within the pericardium.
Where the aorta is most "touching" the left atrium is where the pulmonary veins come in: I think this picture from Gray is most helpful.
Figure 494. Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
There really isn't much to distinguish these veins from the non-auricle part of the atrium, similar to the vena cava on the right side. If you were to cut along the veins eventually you would just open up into the atrium.
The Visible Heart Lab is another good reference http://www.vhlab.umn.edu/atlas/aorta for cardiac anatomy.
The following is multiple choice question (with options) to answer.
The heart and the arteries and veins are associated with what system of the body? | [
"cardiovascular",
"respiration",
"metabolism",
"digestion"
] | A | Cardiovascular System: Arteriosclerosis Compliance allows an artery to expand when blood is pumped through it from the heart, and then to recoil after the surge has passed. This helps promote blood flow. In arteriosclerosis, compliance is reduced, and pressure and resistance within the vessel increase. This is a leading cause of hypertension and coronary heart disease, as it causes the heart to work harder to generate a pressure great enough to overcome the resistance. Arteriosclerosis begins with injury to the endothelium of an artery, which may be caused by irritation from high blood glucose, infection, tobacco use, excessive blood lipids, and other factors. Artery walls that are constantly stressed by blood flowing at high pressure are also more likely to be injured—which means that hypertension can promote arteriosclerosis, as well as result from it. Recall that tissue injury causes inflammation. As inflammation spreads into the artery wall, it weakens and scars it, leaving it stiff (sclerotic). As a result, compliance is reduced. Moreover, circulating triglycerides and cholesterol can seep between the damaged lining cells and become trapped within the artery wall, where they are frequently joined by leukocytes, calcium, and cellular debris. Eventually, this buildup, called plaque, can narrow arteries enough to impair blood flow. The term for this condition, atherosclerosis (athero- = “porridge”) describes the mealy deposits (Figure 20.14). |
SciQ | SciQ-2150 | microbiology, population-biology
Title: How many eukaryotes are there on Earth? I have been reading:
William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF]
wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.
I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above? Could not fit in a comment....
To make sure we all understand your question...
Is your question how many (eukaryote) species are currently living? or How many (eukaryote) cells are currently living??
Just a hint to answer the question
Micheal Lynch, in his book (On the Origin of Genome Architecture) at page 3, Box 1.1 tries to answer the question How much DNA is there on earth?. He ends up with an estimation of a total length of DNA on earth of $10^{24}$ km for procaryotes, $10^{25}$ km for eukaryote (of which $\frac{1}{1000}$% is accounted to humans). This sums up to a total DNA length of $10^{12}$ light-years, or 10 times the diameter of the known universe!
In his calculations, he estimates that the total number of procaryote cells at $10^{30}$ (citing Whitman et al. 1998 as you did). He estimates the total number of eukaryote species to $10^7$, i.e. 6 times the number of known eukaryote species. However, he doesn't directly give any reference for this estimate but he refers to different chapters in the book that contain lots of references.
...I hope that helps...
The following is multiple choice question (with options) to answer.
What do scientists believe are the oldest eukaryotes? | [
"protists",
"arthropods",
"prokaryotes",
"worms"
] | A | Scientists think that protists are the oldest eukaryotes. They most likely evolved from prokaryotic cells, as explained by the endosymbiotic theory. This theory is well-supported by evidence. |
SciQ | SciQ-2151 | At some point, all work needs a public airing to improve. That time for me is now. Thank you in advance on behalf of my students for any feedback.
## Chemistry, CAS, and Balancing Equations
Here’ s a cool application of linear equations I first encountered about 20 years ago working with chemistry colleague Penney Sconzo at my former school in Atlanta, GA. Many students struggle early in their first chemistry classes with balancing equations. Thinking about these as generalized systems of linear equations gives a universal approach to balancing chemical equations, including ionic equations.
This idea makes a brilliant connection if you teach algebra 2 students concurrently enrolled in chemistry, or vice versa.
FROM CHEMISTRY TO ALGEBRA
Consider burning ethanol. The chemical combination of ethanol and oxygen, creating carbon dioxide and water:
$C_2H_6O+3O_2 \longrightarrow 2CO_2+3H_2O$ (1)
But what if you didn’t know that 1 molecule of ethanol combined with 3 molecules of oxygen gas to create 2 molecules of carbon dioxide and 3 molecules of water? This specific set coefficients (or multiples of the set) exist for this reaction because of the Law of Conservation of Matter. While elements may rearrange in a chemical reaction, they do not become something else. So how do you determine the unknown coefficients of a generic chemical reaction?
Using the ethanol example, assume you started with
$wC_2H_6O+xO_2 \longrightarrow yCO_2+zH_2O$ (2)
for some unknown values of w, x, y, and z. Conservation of Matter guarantees that the amount of carbon, hydrogen, and oxygen are the same before and after the reaction. Tallying the amount of each element on each side of the equation gives three linear equations:
Carbon: $2w=y$
Hydrogen: $6w=2z$
Oxygen: $w+2x=2y+z$
where the coefficients come from the subscripts within the compound notations. As one example, the carbon subscript in ethanol ( $C_2H_6O$ ) is 2, indicating two carbon atoms in each ethanol molecule. There must have been 2w carbon atoms in the w ethanol molecules.
The following is multiple choice question (with options) to answer.
What are used to balance chemical equations? | [
"coefficients",
"densities",
"outputs",
"isotopes"
] | A | Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction. |
SciQ | SciQ-2152 | physical-chemistry, thermodynamics, equilibrium
Title: Determining if reaction is endothermic or exothermic using equilbrium constant
For the following reaction
$$\ce{W(s) + 4 Br(g) <=> WBr4(g)}$$
at $\pu{900 K},$ $K_p = 100$ and at $\pu{2800 K}$, $K_\mathrm{p} = 5.$
Determine if the reaction is endothermic or exothermic.
At higher temperatures, the equilibrium has shifted towards the reactants since $K_p$ is significantly smaller. However, how do we determine if a reaction is endothermic or exothermic from this information?
If the reaction was endothermic, an increase in temperature would push the equilibrium to products to counteract the increase in heat. However, the equilibrium has been pushed to the reactants thus signifying the reaction is exothermic. But this assertion is on the assumption that the forward reaction is exothermic. Think about it this way. In an exothermic reaction that is at equilibrium the forward reaction has a lower activation energy. So, if you increase T the forward reaction rate increases but the reverse rate increases even more. That's because the rates of reactions with higher activation energy are more sensitive to temperature. With the reverse rate higher more reactants will be made until the concentration reactants reaches a point where the rate of the forward reaction equals the reverse rate.
In an endothermic reaction increasing T increases the forward rate more than the reverse, producing more product until the increased product concentration causes the reverse rate to equal the forward rate.
The equilibrium constant can be thought of as a ratio of products to reactants needed to equalize the rates of two reactions with different activation energies.
The following is multiple choice question (with options) to answer.
Endothermic and exothermic reactions differ in whether the products or reactants store more of what? | [
"Motion energy",
"Kinetic Energy",
"chemical energy",
"Thermal energy"
] | C | A: The energy is stored in the bonds of the products as chemical energy. In an endothermic reaction, the products have more stored chemical energy than the reactants. This is represented by the graph on the left in the Figure below . In an exothermic reaction, the opposite is true. The products have less stored chemical energy than the reactants. You can see this in the graph on the right in the Figure below . |
SciQ | SciQ-2153 | inorganic-chemistry, electrochemistry, redox, transition-metals, alloy
Title: Separating nickel coin into copper and nickel components I'm trying to create a high school level lab in which we separate the metals in an alloy. The objective is to understand and apply standard reduction potentials, and also to do some extra redox reactions to reclaim solid metals. Plus I think it might be fun!
My plan was to simply submerge nickels in an acidic solution. Theoretically, as long as I don't use nitric acid, the nickel will dissolve and leave the solid copper. I tried it out in the fume hood (1 nickel, 100mL 5M HCl solution), but didn't see the telltale blue/green of nickel ions. I tried sanding the nickel, in case there was an inert oxide layer. For a few minutes, I saw a tiny bit of hydrogen evolution, then the sanded surface turned black.
I read that magnesium is sometimes added to coins for corrosion resistance, which is probably why I'm having problems. Does anyone have suggestions to make this lab possible? Maybe some electrochemistry? I recommend to dissolve the copper-nickel alloy in nitric acid and determine the dissolved $\ce{Cu(II)}$ by iodometric titration.
The following is multiple choice question (with options) to answer.
What is the conversion of metals from their ores to more useful forms called? | [
"nanotechnology",
"metallurgy",
"thermodynamics",
"crystallography"
] | B | Summary The conversion of metals from their ores to more useful forms is calledmetallurgy, which consists of three general steps: mining, separation and concentration, and reduction. Settling and flotation are separation methods based on differences in density, whereas pyrometallurgy is based on a chemical reduction at elevated temperatures, and hydrometallurgy uses chemical or electrochemical reduction of an aqueous solution. In pyrometallurgy, a reductant must be used that does not form stable compounds with the metal of interest. In hydrometallurgy, metals are separated via the formation of metal complexes. |
SciQ | SciQ-2154 | entomology, parasitology, parasitism
The male (microgametocytes) and female (macrogametocytes) gametocytes are ingested by a female Anopheles mosquito during a blood meal (8) - only female mosquitoes (of pretty much any species) drink blood. The parasites' multiplication in the mosquito is known as the sporogonic cycle (stage C). While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes (9). The zygotes in turn become motile and elongated (ookinetes) (10) which invade the midgut wall of the mosquito where they develop into oocysts (11). The oocysts grow, rupture, and release sporozoites (12), which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle (1).
Sources
The following is multiple choice question (with options) to answer.
What is the predominant stage in the life cycle of most scyphozoans? | [
"medusa",
"hydra",
"spore",
"gamete"
] | A | |
SciQ | SciQ-2155 | organic-chemistry, reaction-mechanism, halides
Title: What is the nucleophile in alkaline hydrolysis of a haloalkane? We know that haloalkanes are able to undergo $\mathrm{S_N1}$ or $\mathrm{S_N2}$ in alkaline hydrolysis, and the hydroxide ion is the nucleophile responsible for attack. But when we talk about hydrolysis, isn't it a reaction with water? Where does the hydroxide ion that attacks the haloalkane really come from; the water, or the alkaline catalyst? Consider the reaction of a haloalkane with aqueous sodium hydroxide to produce the alcohol plus sodium chloride. The net reaction consumes one hydroxide ion for each alcohol molecule produced, so it is not really correct to refer to it as a catalyst.
(1) If this reaction occurs via the $\mathrm{S_N2}$ mechanism, a one-step displacement mechanism, you are correct to say that hydroxide (being a much better nucleophile than neutral water) is the nucleophile attacking carbon.
(2) If the reaction occurs via the $\mathrm{S_N1}$ mechanism (note that which mechanism is preferred depends on the structure of the haloalkane, and in some cases a haloalkane can react via both mechanisms), you have a two-step process in which the haloalkane initially dissociates (a slow step) to form a carbocation plus halide ion. The carbocation then reacts very rapidly with whatever nucleophile is handy to form the alcohol. Water is likely more abundant than hydroxide, and is a strong enough nucleophile to react instantly with a carbocation, so most of the product will be formed that way, with release of $\ce{H+}$, rather than by combination of the carbocation directly with hydroxide. The $\mathrm{S_N1}$ reaction of a haloalkane in this manner with excess water or other polar solvent is often referred to as a "solvolysis" reaction.
The following is multiple choice question (with options) to answer.
The reaction of an alkyl halide with an inorganic hydroxide base at elevated temperature produces what? | [
"methane",
"an alcohol",
"blood",
"yeast"
] | B | The reaction of an alkyl halide with an inorganic hydroxide base at elevated temperature produces an alcohol. The molecular reaction to produce methanol from iodomethane and sodium hydroxide is shown below. |
SciQ | SciQ-2156 | biochemistry
Title: Numbering amino acid residues While reading about primary structures of protein, I came across the following image.
What do the numberings $n-1, n, n+1$ in the below image refer to?
I thought about it : The amino acid residues are numbered from 1 to n starting from the N-terminus to the C-terminus .
But the image below shows only a part of the protein.. so why is the last residue numbered $n+1$ instead of $n$ also, why is this shown as termination?
I looked out few papers.. but they seem to be very technical and beyond the scope of my understanding. This question is a bit hard to answer for me without more context.
However, it is clear that the n refers to the tyrosine which is highlighted in the figure as well (especially the interaction of its phenol). The other positions (n+1, n-1) are shown relative to the tyrosine.
I'm unsure about the role of tyrosine in the primary structure of proteins, but maybe this is more clearly explained where you found the figure. I'm also unsure if the glutamic acid is terminal.
The following is multiple choice question (with options) to answer.
What sequence is the primary structure of a protein? | [
"amino acid sequence",
"processed acid sequence",
"nucleic acid sequence",
"proteins acid sequence"
] | A | The amino acid sequence is the primary structure of a protein. As explained in Figure below , a protein may have up to four levels of structure, from primary to quaternary. The complex structure of a protein allows it to carry out its biological functions. |
SciQ | SciQ-2157 | experimental-chemistry, analytical-chemistry, electrostatic-energy
If you are frequently measuring magnetic materials, many analytical balances can be configured in a bottom-loading arrangement. In this setup a platform is hooked beneath the balance, and the sample is supported sufficiently far away from the force-restoring motor so that it does not influence the measurement.
The following is multiple choice question (with options) to answer.
What are used to lift large masses of magnetic materials such as scrap iron, rolls of steel, and auto parts? | [
"electromagnets",
"screws",
"Tape",
"Glue"
] | A | Electromagnets find use in many practical applications. Electromagnets are used to lift large masses of magnetic materials such as scrap iron, rolls of steel, and auto parts. |
SciQ | SciQ-2158 | metals
Title: Why does carbon alloy with iron specifically? Everyone knows what an alloy is: it's a metal made by melting two (or more) other metals together.
Unless of course you're talking about steel. That's a metal made by mixing carbon (very much not a metal) into molten iron. But you never hear about carbon alloys with any other metal, and that's kind of strange. If a few percentage points of carbon can turn iron into the miracle metal that is the foundation of the Industrial Age, just imagine what it could do to aluminum or titanium, for example. (Or even bronze, for that matter, which is superior to iron in many ways, from a materials science perspective.)
But you only ever hear about carbon alloying with iron to form steel. So what's so special about iron? It's true they are not common, but there are other alloys that use carbon. Nickel is probably one of the more common metals that form alloys with carbon that have desirable properties. For example, Nickel 200, Nickel 201, and Nickel 205 all contain carbon. (See: http://www.asminternational.org/documents/10192/1852239/ACFA9D7.pdf/d490dee6-620e-4e38-b64d-53dd02c5fc81). Chromium and Tungsten also form alloys with carbon called Stellite Alloys: See http://en.wikipedia.org/wiki/Stellite (although some, but not all, stellite alloys contain iron too).
The following is multiple choice question (with options) to answer.
Carbon behaves as a metal because it conducts which two things well? | [
"heat and electricity",
"heat and water",
"heat and magnetism",
"electricity and oxygen"
] | A | Carbon behaves as a metal because it conducts heat and electricity well. It is a nonmetal because it is black and brittle and cannot be made into sheets or wires. |
SciQ | SciQ-2159 | endocrinology, pathology, experimental, diabetes-mellitus
Title: Growth Hormone and diabetes Growth hormone and insulin like growth factors are diabetogenic, so I assume that people with high growth hormone (say due to pituitary tumor) may be at high risk for diabetes. Has any correlation been established between these two? I know that diabetes is a multifactorial disorder and so only a correlation may be established. Yes:
That GH has an effect on glycaemic control is most evident from the abnormal glucose tolerance seen in acromegalics...
acromegaly is defined as abnormal growth of the hands, feet, and face, caused by overproduction of growth hormone by the pituitary gland.
Such an effect has been known for decades, which makes sense given how interrelated the axes are. Although I think the best evidence is the fact that the side effects of growth hormone therapy says that Some patients have developed diabetes mellitus...
The following is multiple choice question (with options) to answer.
What is the first direct action of growth hormone? | [
"stimulation of triglyceride production",
"stimulation of monoglyceride breakdown",
"stimulation of monoglyceride production",
"stimulation of triglyceride breakdown"
] | D | Hormonal Regulation of Growth Hormonal regulation is required for the growth and replication of most cells in the body. Growth hormone (GH), produced by the anterior portion of the pituitary gland, accelerates the rate of protein synthesis, particularly in skeletal muscle and bones. Growth hormone has direct and indirect mechanisms of action. The first direct action of GH is stimulation of triglyceride breakdown (lipolysis) and release into the blood by adipocytes. This results in a switch by most tissues from utilizing glucose as an energy source to utilizing fatty acids. This process is called a glucose-sparing effect. In another direct mechanism, GH stimulates glycogen breakdown in the liver; the glycogen is then released into the blood as glucose. Blood glucose levels increase as most tissues are utilizing fatty acids instead of glucose for their energy needs. The GH mediated increase in blood glucose levels is called a diabetogenic effect because it is similar to the high blood glucose levels seen in diabetes mellitus. The indirect mechanism of GH action is mediated by insulin-like growth factors (IGFs) or somatomedins, which are a family of growth-promoting proteins produced by the liver, which stimulates tissue growth. IGFs stimulate the uptake of amino acids from the blood, allowing the formation of new proteins, particularly in skeletal muscle cells, cartilage cells, and other target cells, as shown in Figure 37.13. This is especially important after a meal, when glucose and amino acid concentration levels are high in the blood. GH levels are regulated by two hormones produced by the hypothalamus. GH release is stimulated by growth hormone-releasing hormone (GHRH) and is inhibited by growth hormone-inhibiting hormone (GHIH), also called somatostatin. |
SciQ | SciQ-2160 | genetics, bacteriology, species, selection, artificial-selection
Of the total bacterial and fungal isolates that grew, 133 bacterial isolates and 81 fungal isolates were identified by Sanger sequencing... ...When the ASVs were summarized to the genus level, 121 taxa were detected, 77 of which could be assigned to known genera
and
Overall, the number of bacteria (combination of R2A and BA growth) isolated from the ISS from all 24 samples ranged from 6.7 × 103 to 7.8 × 1010 CFU/m2
So quite high numbers of cultivatable bacteria (CFU = colony forming units, a measure of how many bacteria will grow per sampling), indeed as high as those found in a gram of soil, but very low species diversity compared to the soil.
It is still difficult to prove that this is a new species evolved strictly on the ISS, but it does seem logically likely that evolution will happen on the ISS, as it does anywhere that life is present (as far as we know).
The following is multiple choice question (with options) to answer.
What contains the spore-forming asci? | [
"flagella",
"mushroom cap",
"the ascocarps",
"sporozoa"
] | C | |
SciQ | SciQ-2161 | evolution, experimental-design, ecosystem
Title: What insect/invertebrate species evolves fastest? I am starting an experiment in which I will be forcing evolution in a moderately complex species of insect or invertebrate. I am prepared for the possible longevity of this experiment, but i have no clue what species i should use. I would prefer a species that can easily respond to biotic challengers. Reason being, every abiotic factor will be promoting the growth and prosperity of the target species, however every biotic factor will be trying to kill the target species. The species can be aquatic, amphibious or terrestrial. Drosophila melanogaster. (fruit-fly, pomice-fly)
Image, public domain, via Wikipedia 2022.
Development time is under ideal conditions 8.5 days (at 25 Celsius, 77 Fahrenheit), the females produce perhaps 500 eggs per generation which can hatch in 12-15 hours - from the point of view of turnover, you should be able to observe many generations in a short-ish period at one generation per ten days in reasonable conditions.
Their diet is fruit, fungi - both preferably decomposing and are able to be anaesthetised with ether or carbon dioxide.
They have acted as a model organism (eukaryote) for the study of genetics and there are many known mutations, and established ways to produce them (ethyl methane sulfonate, ionising radiation).
The following is multiple choice question (with options) to answer.
Fruit fly and brine shrimp hox genes have evolved independently for how long? | [
"100.32 million years",
"one billion",
"400 million years",
"60.000 million years"
] | C | |
SciQ | SciQ-2162 | homework, embryology
Title: Why are Birds and Reptiles with abundant yolk sac polyspermic? I was given an explanation that birds and reptiles are polyspermic because they have an abundant yolk sac. But how does it explain the thing?
Chicken as an adult is not using in my opinion yolk as an energy source.
Yolk is used during embryogenesis as the primary energy source with blastula and gastrula -stages and during organogenesis, since the embryo needs proteins and energy somewhere.
How does abundant yolk sac make birds and reptiles polyspermic? My professor says that
The yolk sac is not connected to the mechanism of polyspermy or
monospermy. [Amount of yolk inside the oocyte is then again.] The
oocytes of reptiles and birds are yolk rich - polylecithal for instance.
where
lecithal = yolk containing and some pieces of information about here.
The following is multiple choice question (with options) to answer.
Yolk is a very fragile substance found in the eggs of reptiles and needs protection. what serves as protection for the yolk? | [
"eye sac",
"yolk sac",
"dish sac",
"fish sac"
] | B | |
SciQ | SciQ-2163 | gene-expression
Title: How does a gene "know" what to change to? Excuse my ignorance but I've always been curious about this...
For example, a frog is red, but it starts living in a green forest. Over time the frog becomes green to camouflage. But a gene can't see and I'm sure there's no mechanism for color info to be transmitted to individual genes from the brain. So how does a gene know to pick green over, say, blue? Using your example, the gene doesn't know anything. Mutations cause some of the offspring of the red frog to turn green, some to turn blue, some to turn fluorescent yellow, and some stay red. Birds can't see the green ones as well as the others, so more green frogs survive and make more green frogs. The red frogs, the fluorescent yellow ones, the blue ones, mostly get eaten. After a few generations, almost all the frogs are green -- not because the gene knew anything, not because the mutations went in any direction, but because all the other changes were counterproductive and got eaten.
The gene doesn't know anything. It's just a bunch of chemicals that randomly react with cosmic rays, chance, whatever. Most of the changes are irrelevant or actively bad, and the frog that's carrying those particular chemicals doesn't survive. But sometimes the change benefits the frog carrying the particular chemicals and then the frog sends those chemicals down to its progeny.
Obviously this is hugely over-simplified. A short and simple intro to the basics of evolution is Understanding Evolution, by UC Berkeley.
The following is multiple choice question (with options) to answer.
What do tadpoles change into? | [
"adult frogs",
"reptiles",
"mud puppies",
"toads"
] | A | Tadpoles go through many changes to become adult frogs. |
SciQ | SciQ-2164 | sequence-alignment, phylogenetics, genome, phylogeny
Title: What is the most appropriate way to find the most recent common ancestor between two distantly related species I want to specifically find the common ancestor between a lobster and a humans. I suspect it was an aquatic worm of some description. But I want to know about the nervous system of this common ancestor. Because I've now posted several comments, I'll just roll them all up.
For background on the approaches used to identify most recent common ancestors and a high-level look at how animal taxonomy has been inferred, I suggest Lynch 1999.
I think that there are 2 interpretations of this question. If you are interested in just looking up a single MRCA of well-defined clades, such as lobster and human, here are some approaches:
Easy way:
Look at a tree diagram, e.g. this:
Find the tips that correspond to your species of interest (arthropods for lobster, chordata for humans).
Find where they join together in the diagram (the branch labeled "true coelom").
You have your answer, the MRCA is the group of organisms with a true coelom, coelomates.
A more involved way using a database
Go to this website.
Find the group of species 1 (arthropods, protostomes, etc. for lobster, chordata, deuterostomes etc. for human)
navigate around until you see the group containing the two groups (in this case listed as "bilateria"). In this case you are looking for the bilaterian common ancestor.
another database
Go to this website.
Point and click your way to a view where you see your 2 clades of interest (arthropods, chordates in this case). See figure.
Find where they join (in this case, it is less certain about the existence of a coelomate common ancestor, so it just says "bilaterians").
The following is multiple choice question (with options) to answer.
Earthworms and segmented worms belong to what phylum? | [
"bryozoa",
"annelida",
"protazoa",
"nematoda"
] | B | The phylum Annelida is made up of segmented worms such as earthworms . Segmented worms are divided into many repeating segments. There are roughly 15,000 species of annelids. Most belong to one of three classes. A species in each class is pictured in Figure below . See The Cambrian Explosion at http://www. pbs. org/kcet/shapeoflife/episodes/explosion. html for an introduction to annelids. |
SciQ | SciQ-2165 | pathology
Title: Are all diseases caused by organisms (microorganisms)? Are there other causes? Or is it correct to say that all diseases are in fact caused by organisms (microorganisms)? It is not correct to say that all diseases are caused by foreign organisms. Counterexamples are:
Cancer is caused by random genetic mutations in the cells of our body. The mutations can be caused by many factors such as ionizing radiation, smoking, chemical toxins etc.
Diseases such as stroke or heart attack are caused by blood clots blocking the blood flow to essential organs.
Autoimmune diseases are caused by the immune system falsely recognizing cells of the body as foreign and attacking that tissue leading to a wide variety of symptoms.
Alzheimer's disease is caused by chronic neurodegeneration, meaning that the cells in the brain die. The causes are not quite understood but as Alzheimer's usually appears late in life it is likely related to ageing. Also, it is known that some genetic defects can lead to early-onset Alzheimers.
Prion proteins can cause diseases such as Creutzfeldt–Jakob disease also known as mad-cow disease.
Hereditary diseases such as early-onset Alzheimers or ALS are cause by gene defects inherited from the parents.
Toxins can cause chronic diseases such as lead poisoning.
The list probably goes on...
Please note that the first two on the list are the most common cause of death in developed countries.
The following is multiple choice question (with options) to answer.
What are most stis caused by? | [
"parasites",
"vaccines",
"viruses",
"bacteria"
] | D | Many STIs are caused by bacteria. Some of the most common bacterial STIs are chlamydia, gonorrhea, and syphilis. Bacterial STIs can be cured with antibiotics. |
SciQ | SciQ-2166 | 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 is the term for matter that does not let any light pass through it, whether it absorbs light, reflects light, or does both? | [
"obscene",
"artificial",
"opaque",
"devoid"
] | C | Opaque matter is matter that does not let any light pass through it. Matter may be opaque because it absorbs light, reflects light, or does both. Examples of opaque objects are solid wooden doors and glass mirrors. A wooden door absorbs most of the light that strikes it and reflects just a few wavelengths of visible light. A mirror, which is a sheet of glass with a shiny metal coating on the back, reflects all the light that strikes it. |
SciQ | SciQ-2167 | meteorology, atmosphere, carbon, co2, rain
Bear in mind that this assumes an enormous rainfall intensity, 100% CO2 saturation of the water and equilibrium chemical dynamics. After the raindrops hit the ground at least half of it will immediately re-evaporate back into the air, leaving, at absolute most, about 3% of the atmospheric CO2 leached out of the atmosphere that will be available to react with the soil, rock or biosphere. Also consider that this is but one of several important processes affecting CO2 transience, such as photosynthesis, respiration, volcanism, industrial pollution, etc. So the CO2 estimates that you read about are average values. Advection and turbulent air mixing should ensure that the CO2 regains approximately normal concentration within an hour or two after rainfall.
The following is multiple choice question (with options) to answer.
Rain dissolves fertilizer in the soil, what carries it away? | [
"carbon ?",
"runoff?",
"fossils",
"clouds"
] | B | Rain dissolves fertilizer in the soil. Runoff carries it away. The fertilizer ends up in bodies of water, from ponds to oceans. Nitrogen is a fertilizer in the water. Since there is a lot of nitrogen, it causes algae to grow out of control. Pictured below is a pond covered with algae ( Figure below ). Algae use up carbon dioxide in the water. After the algae die, decomposers break down the dead tissue. The decomposers use up all the oxygen in the water. This creates a dead zone. A dead zone is an area in a body of water where nothing grows because there is too little oxygen. There is a large dead zone in the Gulf of Mexico ( Figure below ). The U. S. states outlined on the map have rivers that drain into the Gulf of Mexico. The rivers drain vast agricultural lands. The water carries fertilizer from these areas into the Gulf. |
SciQ | SciQ-2168 | neuroscience
Title: Nervous system : Nerve signals If the electrical signals from all the various organs throughout the body eventually connect to the nerves in the spinal column traveling up to the brain, how does the brain differentiate the different signals. Is the nerve in the spinal column like an electrical conduit with many wires inside? Yes is the simple answer. A nerve will go up to a specific part of the brain which the brain knows corresponds to a certain region of the body. It isn't perfect though e.g. pain in the diaphragm confuses the brain which doesn't recognise that pain must be coming from there so instead tells the body there is shoulder pain, however this is useful in medicine. Another infamous example is pain from heart disease (angina) which causes pain in the jaw and arm. Perhaps even more interestingly, if a nerve is cut and then grows back linking to the wrong nerve it may lead to the completely wrong part of the body being identified when touched. Also if the brain itself is stimulated in these corresponding areas, a person will feel he or she is indeed being touched in a certain part of the body.
The following is multiple choice question (with options) to answer.
Each vertebral body has a large hole in the center through which the nerves of what pass? | [
"steering cord",
"spinal cord",
"Brain Cord",
"layers cord"
] | B | Each vertebral body has a large hole in the center through which the nerves of the spinal cord pass. There is also a notch on each side through which the spinal nerves, which serve the body at that level, can exit from the spinal cord. The vertebral column is approximately 71 cm (28 inches) in adult male humans and is curved, which can be seen from a side view. The names of the spinal curves correspond to the region of the spine in which they occur. The thoracic and sacral curves are concave (curve inwards relative to the front of the body) and the cervical and lumbar curves are convex (curve outwards relative to the front of the body). The arched curvature of the vertebral column increases its strength and flexibility, allowing it to absorb shocks like a spring (Figure 38.8). Intervertebral discs composed of fibrous cartilage lie between adjacent vertebral bodies from the second cervical vertebra to the sacrum. Each disc is part of a joint that allows for some movement of the spine and acts as a cushion to absorb shocks from movements such as walking and running. Intervertebral discs also act as ligaments to bind vertebrae together. The inner part of discs, the nucleus pulposus, hardens as people age and becomes less elastic. This loss of elasticity diminishes its ability to absorb shocks. The Thoracic Cage The thoracic cage, also known as the ribcage, is the skeleton of the chest, and consists of the ribs, sternum, thoracic vertebrae, and costal cartilages (Figure 38.9). The thoracic cage encloses and protects the organs of the thoracic cavity, including the heart and lungs. It also provides support for the shoulder girdles and upper limbs, and serves as the attachment point for the diaphragm, muscles of the back, chest, neck, and shoulders. Changes in the volume of the thorax enable breathing. The sternum, or breastbone, is a long, flat bone located at the anterior of the chest. It is formed from three bones that fuse in the adult. The ribs are 12 pairs of long, curved bones that attach to the thoracic vertebrae and curve toward the front of the body, forming the ribcage. Costal cartilages connect the anterior ends of the ribs to the sternum, with the exception of rib pairs 11 and 12, which are free-floating ribs. |
SciQ | SciQ-2169 | inorganic-chemistry, redox
Coming to the rust question. Rust has puzzled chemists and engineers for decades because it causes millions of dollars of losses every year. Your equation is a very simplistic way of thinking that rust forms in a single step.
$$\ce{4Fe^0(s) + 3 O2(g) + 2n H2O(l) -> 2 Fe2O3·nH2O(s)}$$
It does not proceed in a single step. Our atmospheric chemistry is very complex, you have carbon dioxide, you have sulfur dioxide, nitrogen oxides, ozone, water vapors, sunlight, plenty of free radicals and plenty of minor trace components. Then there are different phases of rust too. You can have a quick look at Google Scholar and one such representative abstract [1].
In short, people still do PhD in this field and one can only imagine how complex corrosion science is.
References
The following is multiple choice question (with options) to answer.
Rust consists of oxides of what element? | [
"iron",
"Aluminum",
"Gold",
"Copper"
] | A | Rust is a combination of several different oxides of iron. The equations below show the steps involved in one of the many processes of rust formation. |
SciQ | SciQ-2170 | water, atmospheric-science, molecules, humidity
Commentary 3: Physics explanation based on molecule movement will be greatly appreciated. While you are at it - I have a hypothesis why humidity of the atmosphere is seldom 100 %. Water molecules are lighter than nitrogen (or average air) molecules and thus water vapour rises upward due to buoyancy. Depending on the temperature and vicinity of open water surfaces, the rate at which water molecules float upward may be faster than the rate of evaporation, resulting in a temporary steady state where relative humidity is below 100 %. The water vapour in the atmosphere is not lost to the space, however. At some point it cools down so much that it condenses. Thus clouds are made, which float until they can't support their own weight (by whatever means, up-drafts, buoyancy...) at which point the liquid water obeys gravity and falls down again. This greatly enhances evaporation rates while cooling the atmosphere down, and thus relative humidity rises to near 100 % while it's raining. Once the rain is done and the excess water is either absorbed or evaporates again, the cycle starts up again. Water molecules are lost to the upper layers of the atmosphere faster than evaporation can supply them, and thus relative humidity falls below 100 % again. How far below depends on the temperature, major air currents, open bodies of water, and so on. With neither evaporation nor condensation is the system then you can regard the water vapor and the dry air as distinct systems each subject to the same boundary conditions and conclude that they will have the same behavior.
Thus the absolute fraction of water will be the same at both ends and the relative humidity will vary.
The following is multiple choice question (with options) to answer.
Rising air currents carry water vapor into what? | [
"atmosphere",
"troposphere",
"ionosphere",
"stratosphere"
] | A | Rising air currents carry water vapor into the atmosphere. As the water vapor rises in the atmosphere, it cools and condenses. Condensation is the process in which water vapor changes to tiny droplets of liquid water. The water droplets may form clouds. If the droplets get big enough, they fall as precipitation —rain, snow, sleet, hail, or freezing rain. Most precipitation falls into the ocean. Eventually, this water evaporates again and repeats the water cycle. Some frozen precipitation becomes part of ice caps and glaciers. These masses of ice can store frozen water for hundreds of years or longer. |
SciQ | SciQ-2171 | evolution, anatomy, organs
Title: Why Is Most Life Symmetrical Externally But Not Internally? Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance.
Take a human for instance, make a line from the top of our head right down the middle. However, internally it is not the same. Our organs excluding the kidneys, lungs, reproductive organs, etc are not symmetrically placed in our body.
The following is multiple choice question (with options) to answer.
Echinoderms have what type of body symmetry? | [
"Reflectional symmetry",
"Translational symmetry",
"radial symmetry",
"Rotational symmetry"
] | C | Echinoderms are marine organisms that make up the phylum Echinodermata. They can be found in the ocean from the equator to the poles. There are roughly 6000 living species of echinoderms. They are among the most distinctive organisms within the animal kingdom. Members of the phylum include sea stars (starfish), sand dollars, and feather stars, shown in Figure below . See “Different But Equal” at http://www. pbs. org/kcet/shapeoflife/episodes/ultimate. html for an introduction to echinoderms. |
SciQ | SciQ-2172 | aqueous-solution, equipment, purification
Title: Microfiltration for saturated solutions of highly hygroscopic compounds? Is it possible to pass saturated solutions of compounds with very high solubility through filters with small pores (e.g. passing a saturated aqueous ZnCl2 solution at 90C through a 2mcm glassfiber filter with the help of partial vacuum)?
Will it work well? Are there preferred methods for this? If not, is there any (reasonable) solution to filter out microparticles from such solutions? Filtration is a mechanical operation. Thus, if you have a solution of $\ce{ZnCl2}$, which (assuming you use water as solvent) dissociated into ions of $\ce{Zn^{2+}}$ and $\ce{Cl^-}$, a typical filter will not retain these ions. Instead of using some vacuum (potential danger to evaporate some solvent, thus altering the concentration of he solution), you may consider filtration under pressure (e.g., across a Schlenk fritt for larger scale, or a syringe filter at smaller scale [e.g., testing a spin coating]).
(credit)
If the solvent capacity for $\ce{ZnCl2}$ is not (this much) temperature dependent, you equally could perform the filtration near room temperature (e.g., $\pu{432.0 g}$ $\ce{ZnCl2}$ per $\pu{100 g}$ of water at $\pu{25 °C}$ listed here).
The following is multiple choice question (with options) to answer.
What is used during filtration to push fluids and solutes, from higher pressure areas to lower pressure areas? | [
"constructs pressure gradient",
"hydrostatic pressure gradient",
"limited pressure gradient",
"magnesium pressure gradient"
] | B | Another mechanism besides diffusion to passively transport materials between compartments is filtration. Unlike diffusion of a substance from where it is more concentrated to less concentrated, filtration uses a hydrostatic pressure gradient that pushes the fluid—and the solutes within it—from a higher pressure area to a lower pressure area. Filtration is an extremely important process in the body. For example, the circulatory system uses filtration to move plasma and substances across the. |
SciQ | SciQ-2173 | biochemistry, photosynthesis
The general question of the production of oxalate is discussed in the following review: Annu. Rev. Plant Biol. 2005. 56:41–71, from which it appears that this is not the case. The actual pathway of production appears to be subject to some disagreement, with most reports tending to the view that ascorbic acid is the precursor but others suggesting that the glycolate pathway operates in certain species.
I do not think this is too surprising if one considers that PEP carboxylase and oxalate formation each occur in (quite different) specialized cells. (And this is a general consideration regarding C4 plant metabolism: it has evolved in a specialized structures for a specific purpose, and is regulated according to the diurnal requirements of the plant.)
The following is multiple choice question (with options) to answer.
How many pathways do plants have for carbon fixation? | [
"four",
"one",
"two",
"three"
] | D | Plants have evolved three pathways for carbon fixation. The most common pathway combines one molecule of CO 2 with a 5-carbon sugar called ribulose biphosphate (RuBP). The enzyme which catalyzes this reaction, ribulose-1,5-bisphosphate carboxylase oxygenase (nicknamed RuBisCo ), is the most abundant enzyme on earth! The resulting 6-carbon molecule is unstable, so it immediately splits into two much more stable 3-carbon phosphoglycerate molecules. The 3 carbons in the first stable molecule of this pathway give this largest group of plants the name “C-3. ”. |
SciQ | SciQ-2174 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What type of substance is any matter that has a fixed chemical composition and characteristic properties? | [
"pure chemical substance",
"seawater chemical substance",
"versatile chemical substance",
"physical substance"
] | A | Pure Substances and Mixtures A pure chemical substance is any matter that has a fixed chemical composition and characteristic properties. Oxygen, for example, is a pure chemical substance that is a colorless, odorless gas at 25°C. Very few samples of matter consist of pure substances; instead, most are mixtures, which are combinations of two or more pure substances in variable proportions in which the individual substances retain their identity. Air, tap water, milk, blue cheese, bread, and dirt are all mixtures. If all portions of a material are in the same state, have no visible boundaries, and are uniform throughout, then the material is homogeneous. Examples of homogeneous mixtures are the air we breathe. |
SciQ | SciQ-2175 | immunology, reproduction, development
Title: How do Sertoli cells protect sperms? I was reading Developmental biology by Gilbert and stumbled upon a fact that Sertoli cells provide protection to the developing sperms with no futher explanation.
I googled it and found a few books mentioning that it protects sperms from cell mediated immunity and antisperm antibodies. Yet I found a website called fertilitypedia that said:
Sertoli cells do not only control the process of spermatogenesis, but they are also responsible for creating so called immunologically privileged area in the testicles. It means, that Sertoli cell manage to keep blood separated from seminiferous tubules through the connection between them, called tight junction. Tight junction keeps bloodborne substances from reaching germ cells, so all stages of germ cells are protected from the body immunity. Tight junction also keeps surface antigens found on developing germ cells from eluding into the bloodstream so no autoimmune reaction could happen. Since Sertoli cells form the block between the blood and lumen of seminiferous epithelium, they are also in control of the entry and exit of nutrients, hormones and other chemicals into the tubules of the testis.
I'm unable to verify this explanation from the cited sources as none contain the mentioned information.
So my question, how does it actually protect the sperms? The Wikipedia pages on Blood-testis barrier and Sertoli cells have some information relevant to your question, with some academic references included.
You could also search for reviews on Sertoli cells on Google Scholar - several of the first returned results seem relevant, if you are able to access them.
The following is multiple choice question (with options) to answer.
Where are sperm produced in the process of spermatogenesis? | [
"ovaries",
"penis",
"intestines",
"testes"
] | D | Sperm are produced in the testes in the process of spermatogenesis. They mature in the epididymes before being ejaculated from the body through the penis. |
SciQ | SciQ-2176 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
What type of energy does chemosynthesis use to make food? | [
"chemical energy",
"carbon energy",
"GRAVITATIONAL energy",
"CHEMICAL energy"
] | A | Some bacterial autotrophs make food using chemosynthesis. This process uses chemical energy instead of light energy to produce food. |
SciQ | SciQ-2177 | molecular-biology, lab-techniques, pcr
Generate insert (often by PCR, but maybe from another plasmid or via a library generation)
Digest insert with appropriate restriction enzymes
Digest backbone with the same enzymes
Ligate backbone and insert
Transform into bacteria
Pick colonies
Screen colonies for insert (See below)
Grow up colonies with successful clones
Prepare plasmid DNA from successful clones
Use that plasmid in experiments.
The following is multiple choice question (with options) to answer.
The polymerase chain reaction is a way of making copies of what? | [
"an enzyme",
"a gene",
"a form",
"a method"
] | B | The polymerase chain reaction is a way of making copies of a gene. It uses high temperatures and an enzyme to make new DNA molecules. The process keeps cycling to make many copies of a gene. |
SciQ | SciQ-2178 | photons, material-science, absorption, optical-materials, glass
Funny thing is, as I wrote this long question, I feel like I answered my own question. Is it basically that whereas the molecules in opaque materials generally convert photons to heat after absorption, those in transparent materials such as glass/water are unable to do so and so must re-emit them? This is a really interesting question, and I worry that you are getting overly bogged down by being unable to focus individually on the different perspectives which are happening at multiple scales. First, let's tackle the more microscopic quantum scale. If we want to understand how light is (or is not) being absorbed by a material, we must first understand what would cause that absorption in the first place. You hit the nail on the head by giving an example of a process that would allow light to be absorbed; absorption of UV-visible light often leads to the excitation of electrons about the various energy levels within the material. A related phenomena might be the absorption of IR light by molecules because of the excitation of the vibrational degrees of freedom into excited states. All together, the various ways that a material may absorb light are collectively determined by the quantum mechanical structure of the material and what levels and states are available. Of course, describing these levels gets increasingly complicated the more complex the material becomes (which is why I have a job!). But there is one key thing you are missing.
While there may be levels present to allow an absorption of light, we still have to ask how likely it is that the light is absorbed! The classic example of such a calculation is Fermi's Golden Rule in perturbation theory for a two level system which relates the probability of absorption to the transition dipole moment between the two states. See MacQuarrie's Physical Chemistry A Molecular Approach, or his Statistical Mechanics for derivations and details. So we not only have to worry about whether there are levels for the light to cause transitions between, but also the probability of this happening at all. This probability analysis becomes more difficult when we then have to consider how frequently the light will actually get an opportunity to be absorbed on its journey.
The following is multiple choice question (with options) to answer.
Energy transfer between what kinds of levels is generally rather inefficient? | [
"producer",
"apex",
"secondary",
"trophic"
] | D | 55.3 Energy transfer between trophic levels is typically only 10% efficient. |
SciQ | SciQ-2179 | homework
Title: How to determine if this blood disorder is recessive or dominant? This question is from "Concepts of Genetics," Klug & Cummings, 10e.
"Thalassemia is an inherited anemic disorder in humans. Affected
individuals exhibit either a minor anemia or a major anemia.
Assuming that only a single gene pair and two alleles are
involved in the inheritance of these conditions, is thalassemia a
dominant or recessive disorder?"
I know from a quick Google search that the disorder is recessive, but how would I come to this conclusion based on the question alone?
Edit: I've spoken to my professor, and he shared his opinion that is essentially the same as canadiener's answer. Thanks to everyone that replied! Given that this is a text book question about classical genetics, you can safely disregard any reality about the disorder.
I'd argue that the two alleles show incomplete dominance. The mild anemia, which is intermediate between healthy individuals and those with severe anemia, can be attributed to heterozygous individuals. In this case, the expression of the functional allele is not enough to compensate for the nonfunctional allele, producing the mutant phenotype.
The following is multiple choice question (with options) to answer.
What kind of conditions are often inherited as simple recessive traits? | [
"genetic neurotransmitters",
"genetic disorders",
"genetic ratios",
"genetic diversivers"
] | B | |
SciQ | SciQ-2180 | exoplanet, albedo, climate
Title: Could diatom blooms affect albedo of an exoplanet? And perhaps display a seasonal variation if the exoplanet has an axial tilt, providing proof of an Earth-like world supporting at least oceans with microbial life? First off, I am rather certain that by diatom bloom you refer to algal bloom which is a seasonal change of sea color, at least here on Earth, the only system we have observed yet. Your question is indeed rather hypothetical, but from a astronomy/ physics points indeed an interesting one.
Next, let me summarize the assumptions I am reading out of your question:
You assume an exoplanet that is mainly covered by water. Such a waterworld is not only existing in movies, but also a common toy system in climate science (of Earth).
The exoplanet is not only habitable, but also has some kind of algae living in its ocean. A strong assumption indeed, but for our calculation, it gives us numbers for how the color and thus the emissivity of the planet changes.
Indirectly, you also assume our hypothetical waterworld has an atmosphere. Why? An waterworld exoplanet would otherwise have already quickly evaoprated evaporated into space. In terms of greenhouse calculation later on, we will assume that the atmosphere consists only of water vapor. This means that our hypothetical exo-algae on waterworld would not necessary be aerobic. After all, we are after the physics here.
Could algae bloom affect the albedo of an exoplanet? Definitivley yes, but the question is, how much. And if we could observe that from Earth would be a whole different question.
What do the assumptions mean in numbers?
The albedo of open ocean water (on Earth) is $\alpha_O = 0.06$. Concerning the algal albedo $\alpha_A$, I found e.g.
a poster "Algal blooms: how are they harming models used for climate management?" by Ian Jenkinson
an article John Raven: The possible roles of algae in restricting the increase in atmospheric CO2 and global temperature
another article by H Gordon, M Jacobs: Albedo of the ocean-atmosphere system: influence of sea foam.
The following is multiple choice question (with options) to answer.
Without dinoflagellate symbionts, corals lose algal pigments in a process called coral bleaching and eventually die, while corals in turn provide protection, making this what type of relationship?. | [
"parasitic",
"idealistic",
"semantic",
"symbiotic"
] | D | Primary Producers/Food Sources Protists are essential sources of nutrition for many other organisms. In some cases, as in plankton, protists are consumed directly. Alternatively, photosynthetic protists serve as producers of nutrition for other organisms. For instance, photosynthetic dinoflagellates called zooxanthellae use sunlight to fix inorganic carbon. In this symbiotic relationship, these protists provide nutrients for coral polyps (Figure 23.29) that house them, giving corals a boost of energy to secrete a calcium carbonate skeleton. In turn, the corals provide the protist with a protected environment and the compounds needed for photosynthesis. This type of symbiotic relationship is important in nutrient-poor environments. Without dinoflagellate symbionts, corals lose algal pigments in a process called coral bleaching, and they eventually die. This explains why reefbuilding corals do not reside in waters deeper than 20 meters: insufficient light reaches those depths for dinoflagellates to photosynthesize. |
SciQ | SciQ-2181 | 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 is the type of reproduction where part of the parent plant is used to generate a new plant? | [
"coaxed reproduction",
"sexual reproduction",
"asexual reproduction",
"byproduct reproduction"
] | C | 32.3 Asexual Reproduction Many plants reproduce asexually as well as sexually. In asexual reproduction, part of the parent plant is used to generate a new plant. Grafting, layering, and micropropagation are some methods used for artificial asexual reproduction. The new plant is genetically identical to the parent plant from which the stock has been taken. Asexually reproducing plants thrive well in stable environments. Plants have different life spans, dependent on species, genotype, and environmental conditions. Parts of the plant, such as regions containing meristematic tissue, continue to grow, while other parts experience programmed cell death. Leaves that are no longer photosynthetically active are shed from the plant as part of senescence, and the nutrients from these leaves are recycled by the plant. Other factors, including the presence of hormones, are known to play a role in delaying senescence. |
SciQ | SciQ-2182 | atmosphere, wind, geography, troposphere, stratosphere
Title: Other than the South Pole where is the windless place on Earth? For this other question "Would this chambered cylinder be possible", preferably near the equator where is a calmest place from the troposphere to the stratosphere where is the windless place one Earth most of the year? Not just the south pole, but 'Ridge A' and many other parts of the high Antarctic Plateau, at or about 4000 metres altitude, are generally recognized as being the least windy. Otherwise, there are a many parts of the high pressure belts at about +/- 30 degrees which have little wind for most of the year. These tend to be very dry deserts where occasional winds have momentum from other regions. On a local scale there are some deep valleys in tropical rain forests. Once you get below the canopy turbulence level they seldom receive winds of any significance - just the lightest breeze from impeded convection. However, records are hard to find because anemometers in such locations are not really representative of anything.
There is an instagram which claims that Fern tree bus stop, in Hobart, Tasmania, is the 'calmest place on Earth'.
But my experience of Hobart is that icy winds in winter can be far from calm.
These things are relative. Compared to the 2100 km/hour winds of Neptune, everywhere on our planet is as close to windless as makes no difference.
The following is multiple choice question (with options) to answer.
What is the name of the wind belt nearest the equator? | [
"trade winds",
"tropical gusts",
"doldrums",
"cyclones"
] | A | The wind belts have names. The Trade Winds are nearest the Equator. The next belt is the westerlies. Finally are the polar easterlies. The names are the same in both hemispheres. |
SciQ | SciQ-2183 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
What two phases does the cell cycle consist of? | [
"outerphase and mitotic",
"interphase and mitotic",
"antecedent and mitotic",
"mitosis and mitotic"
] | B | Figure 10.5 The cell cycle consists of interphase and the mitotic phase. During interphase, the cell grows and the nuclear DNA is duplicated. Interphase is followed by the mitotic phase. During the mitotic phase, the duplicated chromosomes are segregated and distributed into daughter nuclei. The cytoplasm is usually divided as well, resulting in two daughter cells. |
SciQ | SciQ-2184 | mass, nuclear-physics, binding-energy, metrology, elements
Title: When you see the atomic mass number for an element, does it take into account the atomic mass defect? Sometimes I read that the official atomic mass number for an element on the periodic table only includes natural isotope ratios, other times I read that atomic mass defect, number of electrons, etc. is considered. I am confused. It can depend on who has published the table; if you care about isotopic composition of your sample, or nuclide masses, you have to read the documentation carefully.
The periodic table provided by the IUPAC, who are the governing body that actually approve the names of new elements, reports two atomic weights for some elements: a "conventional" weight and a "standard" weight, the second of which seems to be a range for some elements.
The explanatory text below the table refers to the publication Atomic weights of the elements 2013 (IUPAC Technical Report), which says:
The following is multiple choice question (with options) to answer.
Atoms with the same atomic number but different mass numbers are called what? | [
"reactions",
"tropes",
"isotopes",
"organisms"
] | C | Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The chapter on atoms, molecules, and ions introduced the basic idea of nuclear structure, that the nucleus of an atom is composed of protons and, with the exception of 11 H, neutrons. Recall that the number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element. When referring to a single type of nucleus, we often use the term nuclide and identify it by the notation A where X is the symbol Z X, 14 ⎞ Often a nuclide is referenced 6 C⎠. example, 146 C is called “carbon-14. |
SciQ | SciQ-2185 | 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.
Sphenodontia sphenodontia (“wedge tooth”) arose in the mesozoic era and includes only one of what? | [
"traveling genus",
"living genus",
"outside genus",
"inner genus"
] | B | Sphenodontia Sphenodontia (“wedge tooth”) arose in the Mesozoic era and includes only one living genus, Tuatara, comprising two species that are found in New Zealand (Figure 29.26). Tuataras measure up to 80 centimeters and weigh about 1 kilogram. Although quite lizard-like in gross appearance, several unique features of the skull and jaws clearly define them and distinguish the group from the squamates. |
SciQ | SciQ-2186 | genetics, gene-expression, protein-expression
Title: If gene differs between chromosome pair does individual get a mixture of protein shapes? Do diploids such as humans end up with a mixture of two different shaped proteins where the appropriate gene is expressed differently in the two halves of a chromosome pair or is there some governing factor that dictates that only one of the alleles is ever used to direct protein synthesis? Yes, that mixture of shapes can happen. Differences in the nucleotide base sequences between the two alleles of a gene can lead to differences in amino acid sequence, which in some cases large differences in protein shape. One example would be if one allele changed a cystine codon to any other codon, leading to loss of a disulfide bond needed to stabilize the tertiary structure of a protein. For an extreme example, consider a mutation causing sickle-cell anemia; in this case, the disease-causing allele leads to altered shape of the entire red blood cell.
If a heterozygote carries a healthy allele and a disease-causing recessive allele, the protein produced by the healthy allele provides enough activity to mask the lack of activity of the "broken" protein provided by the recessive allele. If, instead of being a true recessive, the disease-causing allele is partially penetrant, then the heterozygote would suffer from the reduced level of the active protein (only one allele is providing the good stuff).
The following is multiple choice question (with options) to answer.
In a heterozygote with one dominant and one recessive allele, which is expressed? | [
"submissive allele",
"dominant allele",
"dominant elements",
"dominant atoms"
] | B | The expression of an organism's genotype is called its phenotype . The phenotype refers to the organism's traits, such as purple or white flowers. Different genotypes may produce the same phenotype. This will be the case if one allele is dominant to the other. Both BB and Bb genotypes in Table 6.1 have purple flowers. That's because the B allele is dominant to the b allele, which is recessive. The terms dominant and recessive are the terms Mendel used to describe his "factors. " Today we use them to describe alleles. In a Bb heterozygote, only the dominant B allele is expressed. The recessive b allele is expressed only in the bb genotype. |
SciQ | SciQ-2187 | audio, terminology
Title: Audio terminology for "rising frequency"? Left is scalogram of exponential chirp, right is of a bunch of these within time shifts (Shepard Tone):
Is there audio terminology for describing this, besides "rising frequency"? Rising pitch? Rising timbre? Would the two cases be described with different phrases (ignore cross-fading etc for the right case, just focusing on the rising aspect)?
The idea's to describe any positive slope in time-frequency - I have a method that does it, and would like an audio-friendly wording to label it. It should also go the other way, for "falling frequency". A few points:
Rising or falling frequency is fine (IMO). For sweeps people often use "up" sweep or "down" sweep.
The slope of a linear sweep can be measured in $Hz/s$ for a log sweep it's better to use "octaves per second".
"Timbre" is definitely wrong here. Timbre is a perceptual quantity that's related to certain frequency areas of high vs low energy but not to the fundamental frequency or pitch.
"Frequency" is a physical quantity. "Pitch" is a perceptual quantity. They are both related but they are definitely not the same. Case in point: The Shephard Tone is an example of where they disagree. The frequency follows a sawtooth wave, but the pitch is continuously rising. The "jump back" of the frequency is not audible. Another one is "missing fundamental". If you have a signal made up of 200Hz, 300Hz, 400Hz, .. the perceived pitch will be that of a 100Hz sine wave despite the signal not containing any energy at 100Hz at all.
Best practice: if you describing something physical use a physical terminology, if you describing human perception use a perceptual quantity.
The following is multiple choice question (with options) to answer.
Any sound with a frequency above the highest audible frequency is defined as what, a phenomenon useful in medical diagnosis and therapy? | [
"radiation",
"laser",
"ultrasound",
"extrasound"
] | C | Any sound with a frequency above 20,000 Hz (or 20 kHz)—that is, above the highest audible frequency—is defined to be ultrasound. In practice, it is possible to create ultrasound frequencies up to more than a gigahertz. (Higher frequencies are difficult to create; furthermore, they propagate poorly because they are very strongly absorbed. ) Ultrasound has a tremendous number of applications, which range from burglar alarms to use in cleaning delicate objects to the guidance systems of bats. We begin our discussion of ultrasound with some of its applications in medicine, in which it is used extensively both for diagnosis and for therapy. Characteristics of Ultrasound The characteristics of ultrasound, such as frequency and intensity, are wave properties common to all types of waves. Ultrasound also has a wavelength that limits the fineness of detail it can detect. This characteristic is true of all waves. We can never observe details significantly smaller than the wavelength of our probe; for example, we will never see individual atoms with visible light, because the atoms are so small compared with the wavelength of light. |
SciQ | SciQ-2188 | physiology
So, now the question is shifted: why do kisspeptin neurons show up only at puberty? We don't know for sure, but it looks like increased levels of E2 could be important for this.
Again, we get into a self-sustaining cycle. Growth of the body generates an increase in E2 production (possibly due to increased volume of the gonads?), which, when over a certain level permits the development of kisspeptin neurons, which will then stimulate the GnRH neurons, resulting in increased LH and E2. We then have more E2 and this makes kisspeptin neuron grow even more etc etc.
The following is multiple choice question (with options) to answer.
Which organ secretes estrogen? | [
"the testes",
"the ovaries",
"the thyroid",
"the kidney"
] | B | The ovaries release the eggs and secrete estrogen. |
SciQ | SciQ-2189 | acid-base
Title: How are CH3COOH molecules ionisied into H+ and CH3OO- It's written in my chemistry book ,under weak acids, that the molecules of organic acids are partially ionised in water into ions. But I don't understand how molecules are ionised.
I'm an ol student. The $\ce{O}$ atom in the $\ce{O-H}$ bond is more electronegative than $\ce{H}$ atom leading to a slight shift of the electron density towards the $\ce{O}$ atom and the development of a small negative charge, $\delta-$ on oxygen atom and $\delta+$ on hydrogen atom.
Now, a water molecule also has an oxygen atom which attracts some electron density towards itself from the two hydrogen atoms on it's sides causing $2\delta-$ charge on itself and a $\delta+$ each on both the hydrogen atoms.
This $2\delta-$ charge having $\ce{O}$ atoms of the water molecules surround and attract the $\ce{H}$ atoms of $\ce{O-H}$ bond of $\ce{CH3COOH}$ molecules due to the $\delta+$ charge on them. The hydrogen atoms of water in turn surround and attract the $\ce{O}$ atom of the $\ce{O-H}$ bond of $\ce{CH3COOH}$ molecules.
This attraction leads to separation of the $\ce{O-H}$ bond releasing $\ce{H+}$ and $\ce{CH3COO-}$ ions with a shell of water molecules surrounding both of these ions and stabilising them.
The following is multiple choice question (with options) to answer.
Water-soluble carboxylic acids ionize slightly in water to form these? | [
"solvents",
"moderately acidic solutions",
"nonacidic solutions",
"very acidic solutions"
] | B | Water-soluble carboxylic acids ionize slightly in water to form moderately acidic solutions. |
SciQ | SciQ-2190 | fluid-dynamics
Title: Efficient way to move water pumping vs circulation I have a basic question about efficiency of pumping.
If I have a well of 100 meters depth, but water filled till top, and I want to circulate the water. What will be most energy efficient. A) Pumping the water to 100 meters head and then discharging the water at top of that well but below water level or B) having a discharge pipe run all the way down to the same level as intake pipe.
Questions
1) with option A, If the well is filled to the top, and discharge point is below water level. Then will the Total Dynamic Head be 10m or 110m and what will be energy required pump 1KG of water.
2) with option B, what will be the energy required ?
3) any other major influences on the pumping energy ? like pressure if the intake depth increases but water level remains same ? Both will be of the same efficiency. It only matters how far you raise water above the surface. Where you take it from within the bulk of the water is irrelevant.
The following is multiple choice question (with options) to answer.
Which kind of irrigation uses much less water than other methods? | [
"mist",
"constant",
"drip",
"solar"
] | C | Drip irrigation uses much less water than other methods. |
SciQ | SciQ-2191 | evolution, mammals, marine-biology
The question remains: why? The most likely explanation is that cetaceans evolved to exploit an unfilled ecological niche or adapted to new niches that formed as a result of plate tectonics or other types of environmental changes that occurred 50-55 million years ago. The niche describes all of the living and non-living resources needed by an organism to survive. Although land-based mammals were increasing in diversity, few or none were present in the oceans. The basic hypothesis is that the early whale-like artiodactyls, like Indohyus and Pakicetus were land-based (terrestrial) mammals that spent most of their time near the water's edge. Over time, they adapted to the niches in the ocean. Fossils like Ambulcetus and Rodhocetus showed clear evidence of swimming ability, with flattened tails and the enlarged rear feet. In addition, the nostrils shifted from the front of the face to the top of the head, which we recognize as the blowhole.
The shift to the aquatic habitat allowed these species to exploit resources that were not available to land-based mammals, thereby reducing competition for the resources. Reduced competition allows more individuals to survive and reproduce.
Similar scenarios are very likely for other marine mammals, such as seals or manatees. They evolved to take advantage of ecological niches that were not filled by other organisms. This basic concept, evolving to fill available niches, is a common outcome of the evolutionary process.
The of adaptation of cetaceans and other mammals to the oceans may be similar to that of the hippopotamus. Hippos spend most of their time in the water, and they show many adaptations that allow them to live in the aquatic environment. The eyes and nostrils of the hippo are high on the head, which allows them to remain almost entirely submerged but still see and smell, as shown below.
(Hippo photo by Johannes Lunberg, Flickr Creative Commons.)
Hippos feed underwaters, they are heavy enough to walk on the bottom of the river, and the mate and give birth underwater. The young can suckle underwater. Clearly, hippos seem to be another mammal that is "returning to water." Similar types of processes must have occurred in cetaceans for them to adapt to the marine habitat.
The following is multiple choice question (with options) to answer.
Fishes were the earliest example of what subphylum, and jawless fishes were the earliest of these? | [
"vertebrates",
"mammals",
"ferns",
"grasses"
] | A | Fishes Modern fishes include an estimated 31,000 species. Fishes were the earliest vertebrates, and jawless fishes were the earliest of these. Jawless fishes—the present day hagfishes and lampreys—have a distinct cranium and complex sense organs including eyes, distinguishing them from the invertebrate chordates. The jawed fishes evolved later and are extraordinarily diverse today. Fishes are active feeders, rather than sessile, suspension feeders. Jawless Fishes Jawless fishes are craniates (which includes all the chordate groups except the tunicates and lancelets) that represent an ancient vertebrate lineage that arose over one half-billion years ago. Some of the earliest jawless fishes were the ostracoderms (which translates as “shell-skin”). Ostracoderms, now extinct, were vertebrate fishes encased in bony armor, unlike present-day jawless fishes, which lack bone in their scales. The clade Myxini includes 67 species of hagfishes. Hagfishes are eel-like scavengers that live on the ocean floor and feed on dead invertebrates, other fishes, and marine mammals (Figure 15.37a). Hagfishes are entirely marine and are found in oceans around the world except for the polar regions. A unique feature of these animals is the slime glands beneath the skin that are able to release an extraordinary amount of mucus through surface pores. This mucus may allow the hagfish to escape from the grip of predators. Hagfish are known to enter the bodies of dead or dying organisms to devour them from the inside. |
SciQ | SciQ-2192 | human-biology, physiology, proteins, amino-acids, diet
Title: Amino Acid requirement + intake in relation to diet + meat type I was arguing with a friend:
I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways.
She said: It isn't just that the killing is cruel, but it doesn't help us, as humans do not derive the same essential amino acids from consuming these less traditional meats (e.g. dogs, cats, etc) like they would from consuming more traditional meats (e.g. cow, pig, goat, etc) She cites her father, a geneticist, as her source.
Question one:
Are my friend and her father correct? Does the consumption of a less traditional meat (e.g. cats, dogs, etc) provide fewer essential amino acids than the consumption of traditional meats (e.g. cows, pigs, chickens, etc)?
Question two:
My friend also made a comment about veganism and vegetarianism (I am a vegetarian), stating that for the same reason as her and her father's above comment, people who exclude meat from their diet need to use supplements. Is this correct, or would it also be possible to just vary diet to obtain these essential amino acids? There is a difference between animals in their requirements for amino acids. For example, cats need high amounts of taurine (and can't make it) and when fed diets lacking enough can go blind. This is why vegans trying to feed vegan diets to their pets can be very bad for the pet. Animal proteins have sufficient taurine for the cat.
However, the meat of a cat or dog is just as a complete source of protein for humans as any other meat. All essential amino acids are there in sufficient ratios. Suggesting otherwise by her father suggests some confusion between the dietary needs of cat vs. the nutritional value of the cat to another predator.
Your second question is easily answered by looking up essential amino acids. Wiki is plenty sufficient to get the gist Wiki Link. In short, most plants don't contain the full complement of amino acids that humans require (and can't make on their own). So to get this full complement, it requires eating multiple plant products that together contain the required amino acids.
From Harvard School of Public Health
The following is multiple choice question (with options) to answer.
What three things do animals require in order to survive? | [
"Sex, Love, Food",
"air, water, food",
"Shelter, Food and love",
"Immunity, blood, water"
] | B | |
SciQ | SciQ-2193 | biochemistry
Title: Is hydrolysis of polypeptides and polysaccharides "anabolic" or "catabolic" When a polysaccharide or polypeptide is hydrolyzed into mono-saccharides or amino acids, the building blocks can be oxidized to release energy. The oxidation is considered to be catabolic since it reduces the building blocks to simple compounds: carbon dioxide, water, ammonia, and releases energy.
Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
Is it proper to call the isolated process of "hydrolysis" of proteins and polysaccharides "catabolic"?
Are protein synthesis, glycogen synthesis, (and triglyceride formation), by dehydration synthesis processes that require energy or release energy. I think that they release energy which is semantically interesting since protein and glycogen synthesis are the main examples of anabolism in the body but may actually release energy which is a key component of the definition of catabolism. Even if the energy released from protein synthesis is not generating ATP directly, wouldn't the heat produced conserve ATP in the long run.
1) Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Under physiological conditions, it is a process that goes forward, i.e. the Gibbs energy is negative. As a consequence, it can happen outside of cells in the absence of ATP. When we eat, the hydrolysis of polysaccharides starts in our mouths, while the hydrolysis of proteins occurs under harsher (acidic) conditions in the stomach and continues in the intestine (slightly basic conditions).
For warmblooded animals like us, exothermic or endothermic is less important, but you could look it up.
2) Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
The following is multiple choice question (with options) to answer.
What is broken during catabolic reactions, such as the breakdown of complex carbohydrates into simple sugars? | [
"bonds",
"ions",
"metals",
"forms"
] | A | Catabolic reactions involve breaking bonds. Larger molecules are broken down to smaller ones. For example, complex carbohydrates are broken down to simple sugars. Catabolic reactions release energy, so they are exothermic. |
SciQ | SciQ-2194 | equilibrium, gas-laws
Title: Addition of inert gas at "constant volume"? My textbook states that
"The addition of inert gases at constant volume does not affect the equilibrium state of the reactants and products contained in that volume."
Although I am not questioning the truth behind this statement, I am very confused by it.
Let us consider a homogeneous gaseous equilibrium system contained within a closed cylinder. The cylinder has a very small hole on its side, through which an inert gas can be pumped in. This is how I visualize the addition of an inert gas to the system. Now, upon introducing a given amount of inert gas into the system, how does the volume remain constant in any way?
While deriving Van der Waals equation for real gases, I learned that the term $V$ in the ideal gas equation stands for the empty space that is available to the gas molecules for movement. Therefore, when we introduce an inert gas into the system, aren't we essentially decreasing this amount of space that is available to the reactant and product molecules for movement?
I am very confused. Please share your insights for it would be tremendously helpful for me. Thanks ever so much in advance :) Regards. The inert gas that you add does not act like a piston, denying part of the volume to the other molecules in the mixture. For a constant volume system comprised of an ideal gas mixture, the partial pressures of the reactants and products do not change when you add the inert gas. It only increases the total pressure, and that change is only because of its own partial pressure. However, if you are not operating in the ideal gas regime, the addition of the inert gas will affect the equilibrium.
The following is multiple choice question (with options) to answer.
The actual amount (mass) of gasoline left in the tank when the gauge hits “empty” is a lot less in the summer than in the winter. the gasoline has the same volume as it does in the winter when the “add fuel” light goes on, but because the gasoline has expanded, there is what? | [
"more mass",
"less mass",
"same mass",
"lower gravity"
] | B | Making Connections: Real-World Connections—Filling the Tank Differences in the thermal expansion of materials can lead to interesting effects at the gas station. One example is the dripping of gasoline from a freshly filled tank on a hot day. Gasoline starts out at the temperature of the ground under the gas station, which is cooler than the air temperature above. The gasoline cools the steel tank when it is filled. Both gasoline and steel tank expand as they warm to air temperature, but gasoline expands much more than steel, and so it may overflow. This difference in expansion can also cause problems when interpreting the gasoline gauge. The actual amount (mass) of gasoline left in the tank when the gauge hits “empty” is a lot less in the summer than in the winter. The gasoline has the same volume as it does in the winter when the “add fuel” light goes on, but because the gasoline has expanded, there is less mass. If you are used to getting another 40 miles on “empty” in the winter, beware—you will probably run out much more quickly in the summer. |
SciQ | SciQ-2195 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What do you call pure substances with unique properties? | [
"structures",
"elements",
"arrangements",
"originals"
] | B | Elements are pure substances with unique properties. There are more than 100 different elements (92 of which occur naturally). The smallest particles of elements are atoms. |
SciQ | SciQ-2196 | 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 is the large muscle that extends across the bottom of the chest below the lungs called? | [
"diaphragm",
"uterus",
"pectoral",
"abdomen"
] | A | Mammals breathe with the help of a diaphragm . This is the large muscle that extends across the bottom of the chest below the lungs. When the diaphragm contracts, it increases the volume of the chest. This decreases pressure on the lungs and allows air to flow in. When the diaphragm relaxes, it decreases the volume of the chest. This increases pressure on the lungs and forces air out. |
SciQ | SciQ-2197 | forces, fluid-statics
Title: Is Frobscottle from the movie 'The BFG' less dense than air? For those who have either read the book, or watched the movie "The BFG", you would know Frobscottle as a green drink the giant uses, and has bubbles fizzing "in the wrong way", which is downwards. Assuming the bubbles to be filled with air, and that gravitational force on the bubble is greater than buoyant force, does this imply Frobscottle is less dense than air? Furthermore, is a liquid possible that is less dense than air? It implies that the author made it up without worrying about physics. If Frobscottle was less dense that air, it wouldn't stay in a cup. It would float like a helium balloon.
There is a liquid less dense than air, but it is nothing you could put air bubbles in. It is 3 monolayers of $He^3$ adsorbed on graphite at temperatures below 80 milliKelvin. First, the liquid is only 3 atoms deep. Second, air freezes solid at that temperature.
See http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/lowest-density-liquid-in-nature/ and https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.109.235306.
The following is multiple choice question (with options) to answer.
What is less dense then either solids or liquids? | [
"dark matter",
"ice",
"gases",
"plasma"
] | C | Gases are less dense that either solids or liquids. |
SciQ | SciQ-2198 | geology, mountains, stratigraphy, mountain-building
Title: What are these geological horizontal lines formed on this mountain called and why they are formed? This images are of Mt. Kailash, Himalaya.
Front face of Mount:
Back face of Mount: What you see are bedding surfaces. They formed horizontally in a sedimentary lacustrine environment, the Kailash Formation.
This is a reconstruction of the paleoenvironment:
.
(Source)
As Gimelist noted, the sedimentary layers formed above a magmatic body.
The question is why they reached an altitude of 8,000 meters and are still horizontal.
It is an extreme example of the principle of original horizontality, which gives the polarity of succession. The materials above are newer than those below because they were deposited horizontally. The tectonic uplift didn't change the original horizontal arrangement.
The following is multiple choice question (with options) to answer.
What is the term for a mountain-building event? | [
"erosion",
"glaciation",
"orogeny",
"volcanism"
] | C | A mountain-building event is called an orogeny . Orogenies take place over tens or hundreds of millions of years. Continents smash into each other. Microcontinents and island arcs smash into continents. All of these events cause mountains to rise. |
SciQ | SciQ-2199 | mechanical-engineering, structures, connections
Title: Can pinned support / pin joint transfer moments in 3D? What's an authoritative definition of whether the idealized pinned support and pin joint can transfer moments in 3D?
Most sources say both of them cannot transfer moments but are apparently only considering 2D. A real pin joint obviously can transfer moments about all axes normal to the pin's axis. So is an implementation of the ideal pin joint really more like a ball joint than a pin joint?
I assume a pinned support is the same as a pin joint but with one end fixed to ground. But maybe they have different numbers of degrees of rotational freedom?
For example, if this support can carry moments about two perpendicular axes (red arrows), would it be correctly called a pinned support?
In comparison, this one has all 3 rotational degrees of freedom, so is it still a pinned support? Yes it can, and in many designs it should be a pin support along one axis and fixed support along other. In many trusses and bridges that is the case.
The design software when defining a joint have the joint degrees of freedom choices. Among those are the option to define the joint a hinge along one axis but fixed along the others.
You can even have joints or supports that can have, rigid, pin, or spring or even predefined varying stiffness and ductility restriction on rotation, settlement, lateral displacement, moment transfer. This is becoming more advantageous in seismic design. Where one expects different behavior of a structure under different spectra of earthquake.
Between the two extremes of a pin joint and fixed join one can define the semi fixed joint or fixed but after a certain stress behaving like a hinge.
In real construction of a joint there is always joints that are legally considered pin or fixed but they behave a certain mix of both, but you design them depending on what the code defines that type ofjoint.
The following is multiple choice question (with options) to answer.
A multiaxial ball-and-socket joint has much more mobility than a what hinge joint? | [
"uniaxial",
"biaxial",
"triaxial",
"quadaxial"
] | A | 9.6 | Anatomy of Selected Synovial Joints By the end of this section, you will be able to: • Describe the bones that articulate together to form selected synovial joints • Discuss the movements available at each joint • Describe the structures that support and prevent excess movements at each joint Each synovial joint of the body is specialized to perform certain movements. The movements that are allowed are determined by the structural classification for each joint. For example, a multiaxial ball-and-socket joint has much more mobility than a uniaxial hinge joint. However, the ligaments and muscles that support a joint may place restrictions on the total range of motion available. Thus, the ball-and-socket joint of the shoulder has little in the way of ligament support, which gives the shoulder a very large range of motion. In contrast, movements at the hip joint are restricted by strong ligaments, which reduce its range of motion but confer stability during standing and weight bearing. This section will examine the anatomy of selected synovial joints of the body. Anatomical names for most joints are derived from the names of the bones that articulate at that joint, although some joints, such as the elbow, hip, and knee joints are exceptions to this general naming scheme. |
SciQ | SciQ-2200 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
Meiosis and mitosis are both preceded by one round of what? | [
"internal fertilization",
"germination",
"cellular respiration",
"dna replication"
] | D | Figure 11.7 Meiosis and mitosis are both preceded by one round of DNA replication; however, meiosis includes two nuclear divisions. The four daughter cells resulting from meiosis are haploid and genetically distinct. The daughter cells resulting from mitosis are diploid and identical to the parent cell. |
SciQ | SciQ-2201 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
What is the hollow sac like organ that stores urine until it is excreted? | [
"kidney",
"tumor",
"ureter",
"bladder"
] | D | hollow, sac-like organ that stores urine until it is excreted from the body. |
SciQ | SciQ-2202 | geology, models, magnetosphere, rock-magnetism
Title: Can living where magnets are abundant provide a mini-magnetoshere? Are there a mini-magnetosphere within the magnetosphere similar to mini-magnetosphere found on the Moon? Is there a map of these areas that would resemble the white swirls in the picture below?
The white areas extending up to 360 km and are the safer areas where one could be protected to a degree.
Are there areas on Earth that could have this magnetic crustal properties as the moon has and would it add or supplement the protection of Earth's magnetosphere?
Source: http://lunarnetworks.blogspot.com/2010/10/grand-lunar-swirls-yielding-to-lro-mini.html Near to the Earth's surface there are small variations in the Earth's magnetic field, but these don't play a role in providing the magnetosphere which protects the Earth from charged particles emanating chiefly from the solar wind.
The following is multiple choice question (with options) to answer.
What is the name of the magnetic material found in lava? | [
"meteorite",
"magnetite",
"magnemite",
"hemoglobin"
] | B | Magnetite is a magnetic mineral found in lava. The magnetite points to the magnetic north pole when it cools. |
SciQ | SciQ-2203 | biochemistry
Title: Is hydrolysis of polypeptides and polysaccharides "anabolic" or "catabolic" When a polysaccharide or polypeptide is hydrolyzed into mono-saccharides or amino acids, the building blocks can be oxidized to release energy. The oxidation is considered to be catabolic since it reduces the building blocks to simple compounds: carbon dioxide, water, ammonia, and releases energy.
Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
Is it proper to call the isolated process of "hydrolysis" of proteins and polysaccharides "catabolic"?
Are protein synthesis, glycogen synthesis, (and triglyceride formation), by dehydration synthesis processes that require energy or release energy. I think that they release energy which is semantically interesting since protein and glycogen synthesis are the main examples of anabolism in the body but may actually release energy which is a key component of the definition of catabolism. Even if the energy released from protein synthesis is not generating ATP directly, wouldn't the heat produced conserve ATP in the long run.
1) Is the process of hydrolysis that breaks up polypeptides and polysaccharides a net endothermic or exothermic process?
Under physiological conditions, it is a process that goes forward, i.e. the Gibbs energy is negative. As a consequence, it can happen outside of cells in the absence of ATP. When we eat, the hydrolysis of polysaccharides starts in our mouths, while the hydrolysis of proteins occurs under harsher (acidic) conditions in the stomach and continues in the intestine (slightly basic conditions).
For warmblooded animals like us, exothermic or endothermic is less important, but you could look it up.
2) Do the free amino acids and monosaccharides have more or less stored energy than the polypeptide or polysaccharide that they were broken down from?
The following is multiple choice question (with options) to answer.
What is a branded polymer that serves as energy storage in animal? | [
"hydrocarbon",
"triglyceride",
"glycogen",
"pathogen"
] | C | Glycogen is a branched polymer of glucose and serves as energy storage in animals. |
SciQ | SciQ-2204 | food, biotechnology
Title: How to increase the shelf life of yogurt without refrigeration? When we make yogurt at home and do not refrigerate it, it will become sour because of conversion of lactose into lactic acid by Lactobacillus bacteria, but this does not happen in case of Nestle's yogurt or any other brand until it remains air tight.
I wonder though bacteria is still present in it and continue to convert lactose into lactic acid then why does not packed yogurt becomes sour? How these companies increase the shelf life of yogurt..? This article gives an excellent review on yogurt manufacturing, but to summarize:
-Raw milk goes through centrifugation to remove somatic cells and other solid impurities.
-Thermalization is conducted at "60–69 °C for 20–30 s, aiming at the killing of many vegetative microorganisms and the partial inactivation of some enzymes."
After this point, the milk may be inoculated with lactic acid bacteria or other microfloras.
-Then, standardization occurs which for milk refers to the standardization of fat and solid-non-fat content (SNF). This in short affects the fermentation process ("an increase of SNF increases the duration of the fermentation process").
-The next step is homogenization, which prevents milk fat from rising to the top of the liquid. This has an effect on the stability of the emulsion.
-I think this step is where "sterility" comes into play, "heat treatment of milk reduces the number of pathogenic microorganisms to safe limits for the consumer’s health. Various heat treatments can be applied, which are classified based on the duration and the temperature. The most common are known as thermalization, low and high pasteurization, sterilization and UHT (Ultra Heat Treatment)." The review goes into more detail about each type and what they eliminate or don't eliminate (spores, vegetative bacteria, etc.).
The following is multiple choice question (with options) to answer.
Milk is usually subjected to what process, where high temperatures denature the proteins in bacteria so they cannot carry out functions needed to grow and multiply? | [
"pasteurization",
"vaporization",
"crystallization",
"Cleaning"
] | A | When milk is pasteurized, it is heated to high temperatures. These high temperatures denature the proteins in bacteria, so they cannot carry out needed functions to grow and multiply. |
SciQ | SciQ-2205 | quantum-mechanics, electricity
Alternatively, you could consider a loop of water employing the analogy with quantities of flow (kg/s) and hydrostatic pressure (J/kg or psi or many other units). An example of this could be something like a flow loop in a nuclear plant, for instance. There exist components that impart pressure to the flow, then there are components that have friction (again, like a resistor) that balance against the work of the pump. The reason this might not be as good of an example is because it requires a pressurized loop, which is further from our common everyday experience.
It is true that the water does not exist in a medium in the same way the electrons in an electric circuit do. This is just one of the many many reasons why the analogs are not perfect. The thing to focus on is that the equations can be the same with different quantities in place. Right now, I'm focused on the most simple laws possible. For instance:
$$V = I R$$
$$P = I V$$
The examples I discussed before can certainly be put in terms of these laws. All that these do is illustrate a case where there is a flow with a unit attached to it, and that flow has a per-unit energy value which dictates how much flow will occur over static components (the resistor case) and then concepts of power (among others) come naturally.
The following is multiple choice question (with options) to answer.
What do you call something that controls the uptake of water or another substance in the environment, in order to maintain constant internal conditions? | [
"osmoregulators",
"osmoconformers",
"sporozoans",
"protozoans"
] | A | |
SciQ | SciQ-2206 | material-science
Title: Wood: A Naturally Occurring Composite Material? In materials science texts, I see wood used an example of a naturally occurring composite material. One of the main components of wood is cellulose, which is a polymer. But what other component makes it a composite?
Thanks for any clarification. the two components of wood-as-a-composite are cellulose fibers and lignin, the resin in which the cellulose fibers are embedded. Cellulose furnishes strength in tension and the resin furnishes strength in shear.
The following is multiple choice question (with options) to answer.
Plastics are common examples of synthetic polymers of what abundant element? | [
"carbon",
"silicon",
"hydrogen",
"silver"
] | A | Synthetic carbon polymers are produced in labs or factories. Plastics are common examples of synthetic carbon polymers. You are probably familiar with the plastic called polyethylene. All of the plastic items pictured in the Figure below are made of polyethylene. It consists of repeating monomers of ethylene (C 2 H 4 ). Structural formulas for ethylene and polyethylene are also shown in the Figure below . To learn more about synthetic carbon polymers and how they form, go to this URL: http://www. youtube. com/watch?v=7nCfbZwGWK8. |
SciQ | SciQ-2207 | geophysics, earth-history, geomagnetism, paleomagnetism
Title: How did the intensity of Earth's magnetic field change through geological time? Looking at the wikipedia article on the Earth's magnetic field, I see that its strength varies through time. How did Earth's magnetic field change throughout its history, from the beginning of the Archean period (~4 billions years ago) to today?
My current attempt
All I found so far is this graph from wikipedia (which is on a too short time scale) and this kind of text (not a science paper) reporting an estimate for a given time point (3.2 billions years ago) reporting a field of about 25 microTeslas. The Earth's initial accretion was about 4.5 billion years ago, and there is good Hf-W isotopic evidence that an iron core started to form within about 10 M years, and may have been largely complete within 30 M years. However, the Earth's dynamo, which is driven by isotopic heating and core rotation/convection, didn't switch on strait away. It must have built up over hundreds of millions of years, possibly kick-started by a the magnetic field of a stronger solar wind at that time. The evidence from 3.5 Bn year old dacites suggest that the magnetic field at that time was only 30 to 50% of the current value. There is no magnetic data for 4.4 to 3.5 Bn years, (the time period you are interested in), but current models lean towards lower rather than higher values. There appears to be no mechanism for strong magnetism in the early Earth. Geomagnetic evidence from about 2.5 Bn years ago seems to indicate that the Earths magnetism was more stable then than now, with few if any peaks of high or low magnetism. Probably the Earth's early magnetic field will always be imprecisely known because nearly all the early rocks have been 'cooked' in such a way as to extinguish the early magnetic evidence.
The following is multiple choice question (with options) to answer.
Magnetite crystals of different ages and on different continents pointed to different spots. the simplest explanation is that the continents have done what? | [
"evolved",
"changed",
"moved",
"reacted"
] | C | Magnetite crystals of different ages and on different continents pointed to different spots. The simplest explanation is that the continents have moved. |
SciQ | SciQ-2208 | 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.
Protozoa can be classified on the basis of how they? | [
"look",
"move",
"feel",
"smell"
] | B | Protozoa can be classified on the basis of how they move. As shown in Table below , protozoa move in three different ways. Only sporozoa cannot move. Note that this classification is based only on differences in movement. It does not represent phylogenetic relationships. |
SciQ | SciQ-2209 | homework-and-exercises
Title: Is geothermal energy ultimately derived from solar energy? The following question is taken from 10th class science NCERT book chapter 14th.
Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
(a) geothermal energy (b) wind energy
(c) nuclear energy (d) bio-mass.
The answer is given as (c) nuclear energy.
I understand that the wind moves because of the uneven heating of the earth by the sun. And biomass uses solar energy for photosynthesis.
How is geothermal energy ultimately derived from the sun? It is not a correct statement:
Geothermal energy comes from the heat within the earth. The word "geothermal" comes from the Greek words geo, meaning earth," and therme, meaning "heat." People around the world use geothermal energy to produce electricity, to heat buildings and greenhouses, and for other purposes.
The earth's core lies almost 4,000 miles beneath the earth's surface. The double-layered core is made up of very hot molten iron surrounding a solid iron center. Estimates of the temperature of the core range from 5,000 to 11,000 degrees Fahrenheit (F). Heat is continuously produced within the earth by the slow decay of radioactive particles that is natural in all rock
italics mine.
Geothermal energy comes from the original energy of the matter solidifying into the sun-planetary system, ultimately from the Big Bang, and from continuous nuclear decays and reactions .
The following is multiple choice question (with options) to answer.
Biomass, solar, wind, water, and geothermal power are examples of what kinds of energy resources? | [
"fossil fuel",
"mechanical",
"renewable",
"electrical"
] | C | Renewable energy resources include solar, water, wind, biomass, and geothermal power. These resources are usually replaced at the same rate that we use them. Scientists know that the Sun will continue to shine for billions of years. So we can use the solar energy without it ever running out. Water flows from high places to lower ones. Wind blows from areas of high pressure to areas of low pressure. We can use the flow of wind and water to generate power. We can count on wind and water to continue to flow! Burning wood ( Figure below ), is an example of biomass energy. Changing grains into biofuels is biomass energy. Biomass is renewable because we can plant new trees or crops to replace the ones we use. Geothermal energy uses water that was heated by hot rocks. There are always more hot rocks available to heat more water. |
SciQ | SciQ-2210 | physical-chemistry, thermodynamics, stability, solid-state-chemistry
By definition a more stable compound decomposes less readily. Decomposition here refers to the reverse of reaction (1).
When comparing the tabulated oxides, a more stable oxide has a more negative free energy of formation. Therefore $ \ce{ZnO(s)}$ is the most stable of the oxides relative to oxygen and the reduced metal. Of the metals the mercury(II) oxide would require the least energy to reduce.
Note that for all of the reactions here
$$K = p^\circ/p_\ce{O2}$$
where $p^\circ=\pu{1 bar}$ (assuming the pressure is low). When starting from metal oxides, allowed to decompose until at equilibrium, a less stable oxide is at equilibrium with a higher partial pressure of oxygen (smaller K) due to more of the oxide decomposing. Therefore imagine you have an evacuated box containing the oxide of one metal and an amount of another metal in pure (reduced) form. If the equilibrium partial pressure $p_\ce{O2}(\text{eq})$ for the oxide is higher than $p_\ce{O2}(\text{eq})$ for the oxide of the second metal, then (if you wait long enough) all of the oxide will be reduced and the second metal oxidized until either the original oxide or pure metal is exhausted.
The enthalpies of formation refer to how much heat evolves when 1 mole of the oxide is formed from the reagents at constant T and p, with all compounds in their standard states. The more negative the value the more heat is released (the reaction is more exothermic). The oxidation of zinc is the most exothermic reaction (per mole of product formed) of those shown in the table.
The following is multiple choice question (with options) to answer.
What type of gases are the least reactive of all elements? | [
"brave",
"humble",
"noble",
"lucky"
] | C | Noble gases are the least reactive of all elements. That’s because they have eight valence electrons, which fill their outer energy level. This is the most stable arrangement of electrons, so noble gases rarely react with other elements and form compounds. |
SciQ | SciQ-2211 | evolution, biochemistry, mitochondria
Title: Is there any advantage of having mitochondria for aerobic respiration? If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and eukaryotes. In prokaryotes all these processes take place in cytoplasm while in eukaryotes the last two processes take place in mitochondria.
So is there any advantage of performing the last two processes in the mitochondria? Does it yield more energy? If there is no advantage, what is the point of having a mitochondria (at least for this process)? From the evolutionary point of view, the eukaryotes acquired these metabolisms (except glycolysis) from their prokaryotic endosymbionts. Not all prokaryotes have the ETC. The free living ancestor of mitohondria is supposed to be the alpha-proteobacterium.
Now, glycolysis is a common pathway in lot of lifeforms perhaps because of abundance of glucose. TCA cycle is coupled with ETC at certain steps which makes it essentially a part of aerobic metabolism.
The reason for having a dedicated organelle for respiration
ATP synthesis is a membrane process. Imagine a large prokaryotic cell- as big as an animal cell. Such a cell cannot take care of its energetic demands which primarily consists of protein synthesis with the given area of membrane i.e it needs much more ATP-synthases than it can have to cope up with the energy demands of maintaining such a huge cell (this index is approximated based on surface to volume ratio). Therefore it is wise to harbor multiple efficient organelles i.e. mitochondria which themselves have just a small essential genome and proteome to maintain.
For a better understanding, please read this article. I just loved it.
There is also a book by the same author about mitochondria called Power, Sex, Suicide.
The following is multiple choice question (with options) to answer.
The cells of most eukaryotic and many prokaryotic organisms can carry out what type of respiration? | [
"energetic",
"aerobic",
"kinetic",
"anaerobic"
] | B | |
SciQ | SciQ-2212 | mantle, crystallography, crystals, pressure, diamond
That’s because the Botswana diamond also contained a high-pressure form of ice as well as another high-pressure mineral known as wüstite (SN: 3/8/18). The presence of those inclusions helped narrow down the rough pressures at which the davemaoite might have formed: somewhere between 24 billion pascals and 35 billion pascals, Tschauner says. It’s hard to say exactly what depth that corresponds to, he adds. But the discovery directly links heat generation (the radioactive materials), the water cycle (the ice) and the carbon cycle (represented by the formation of the diamond itself), all in the deep mantle, Tschauner says.
From the article I think that I'm being told that the diamond is preserving enough pressure to keep both the "davemaoite" and " a high-pressure form of ice" and the wüstite stable as well.
Am I understanding this correctly?
Question: When diamonds "migrate" from deep underground to the surface, do they maintain pressure inside when there is no more pressure outside? If so, how?
I would think that as the diamond rises to the surface and the pressure relaxes outside it would relax and expand uniformly and the pressure would relax inside as well. If that's not the case, why not?
The following is multiple choice question (with options) to answer.
What kind of rock's makeup is changed by heat and or pressure? | [
"tectonic",
"igneous",
"basaltic",
"metamorphic"
] | D | Metamorphic rocks start off as some kind of rock. The starting rock can be igneous, sedimentary or even another metamorphic rock. Heat and/or pressure then change the rock’s physical or chemical makeup. |
SciQ | SciQ-2213 | universe, cosmology
Conclusion
I'm sure you could think up a lot of different types of other energies you might want to include in this, but hopefully you see the point I'm driving at. They're all completely negligible. The arguably largest contribution comes from radiation and that's been shown to be $0.005\%$ of the Universe's mass-energy budget. What we see is that the Universe is dominated by Dark Energy, has a bit of Dark Matter, a small amount of atoms, and negligible amounts of the rest of everything else. And overtime, the Dark Energy portion of that pie chart will get bigger and bigger until we'll be able to throw out atoms and dark matter from the plot as well since they'll be just as insignificant as neutrinos and radiation are now.
The following is multiple choice question (with options) to answer.
Most scientists think that ordinary matter makes up how much of the total matter in the universe? | [
"less than half",
"about half",
"more than half",
"greater than half"
] | A | Most scientists who study dark matter think it is a combination. Ordinary matter is part of it. That is mixed with some kind of matter that we haven’t discovered yet. Most scientists think that ordinary matter is less than half of the total matter in the Universe. |
SciQ | SciQ-2214 | mechanical-engineering, civil-engineering, applied-mechanics, statics, dynamics
Title: Finding downward force of lever bar I am working on a DIY project, I am trying to replicate a bar compressor which for some reason is only sold in Europe so I thought it would be fun to make my own without having to waste so much material. I simply want to make sure the force going down with the plate somewhat replaces a person to jump in the trashcan. Somewhere above 80+ lbs, since I am no engineer I was wondering how would one go about finding the force applied going down to the trash if about 50lbs is pulling down the lever. I understand that materials are key to this but as an amateur I just wanted to know how to get started. Sorry for posting here but I thought it would suit this page the most for this question. Thank you. The input force is 18.5+20.5 ft away from the fulcrum and the load is 18.5 away from the fulcrum.
This means the force applied to the load is $\frac{(18.5+20.5)}{18.5} = 2.1$ times greater than the input force or for an input force of 50 lbs you get an output force of 105 lbs.
However this assumes that all forces are applied perpendicular to the line between point and fulcrum. If this is not the case then you need to decompose the forces into tangential and normal components.
The following is multiple choice question (with options) to answer.
In machines that increase force, such as ramps and doorknobs and nutcrackers, what is the relation between output and input force? | [
"output is smaller",
"drop is greater",
"input is greater",
"output is greater"
] | D | For machines that increase force — including ramps, doorknobs, and nutcrackers — the output force is greater than the input force. Therefore, the mechanical advantage is greater than 1. |
SciQ | SciQ-2215 | cosmology
Title: galaxies in a specific radius in different shapes of universe Let the distribution of galaxies be a number like $n$. we want to find the total number of galaxies within the radius $r$ from a specified point. in which shape of the universe (flat, open, closed) the number we get is higher? ($n,r$ are the same in this universes and only the area (volume) in each universe is different). It seems clear to me that this is a homework question. I believe what the question is after is to look at the equations for distances in the universe as a function of curvature and see how this curvature affects things. Read, for example, sources like this one or this one.
As with most of things in cosmology, there's lots of equations and many ways to write them. A relevant equation would be the following angular diameter distance:
$$D_M = (1+z)^{-1}
\begin{cases}
\frac{1}{\sqrt{\Omega_k}}\sinh\left(\sqrt{\Omega_k}D_c/D_H\right), & k = -1 \\
D_c, & k = 0 \\
\frac{1}{\sqrt{\left|\Omega_k\right|}}\sin\left(\sqrt{\left|\Omega_k\right|}D_c/D_H\right), & k = +1 \\
\end{cases}
$$
In this case, you can see the three forms it takes for a closed universe ($k=-1$), a flat universe ($k=0$), and an open universe ($k=+1$). It should be pretty clear that if you chose some volume with some radius calculated by $D_A$, you'd get different volume sizes and thus different amounts of galaxies in each volume for the three universe types.
By looking at the equations and playing around with them, you should be able to convince yourself which universe type results in the largest volume.
The following is multiple choice question (with options) to answer.
What type of galaxies are oval shaped, red or yellow, and contain mostly old stars? | [
"typical elliptical",
"ovoid anomalies",
"unique elliptical",
"mutant ellipses"
] | A | Typical elliptical galaxies are oval shaped, red or yellow, and contain mostly old stars. |
SciQ | SciQ-2216 | thermodynamics
Title: Nature of spontaneous reactions The definition of spontaneous process states that "A spontaneous process is an irreversible process and maybe reversed by some external agency"
So, can we say that all spontaneous reactions are irreversible reactions under the absence of some external force? A spontaneous reaction, as contrasted with a non-spontaneous reaction, is a reaction quantified by a negative free energy change. A reaction is said to be spontaneous if it occurs without being driven by an outside force. So, we can say: In any spontaenous process, the path between the reactants and products is irreversible
The following is multiple choice question (with options) to answer.
What is the term for something in the environment that causes a reaction in an organism? | [
"climate",
"stimulus",
"pollution",
"crisis"
] | B | When a living thing responds to its environment, it is responding to a stimulus. A stimulus ( stimuli, plural ) is something in the environment that causes a reaction in an organism. The reaction a stimulus produces is called a response . |
SciQ | SciQ-2217 | neuroscience, brain, brain-stem
On the contrary, if the ARAS is working normally but the consciousness neural process is not, there can be alertness without, with minimal, or with some awareness. The degree of impairment of awareness depends on how much the consciousness neural process is dysfunctional. For example, in the case of damages to the consciousness neural process from diffuse cerebral hypoxia, extensive bilateral cerebral infarcts, or diffuse cerebral cortical injury, the results can be various abnormal conscious awareness’s states that range in severity of abnormal conscious awareness, depending on how much the consciousness neural process is impaired, such as (from mild to severe) acute confusional state, akinetic mutism, minimally conscious state (MCS), and vegetative state (VS). In the latter two categories, which are severe conditions, the patients can open eyes and have some reflex responses, such as blinking, chewing, and yawning, but show no (in VS) or minimal (in MCS) signs of conscious awareness of self and the environment (by clinical testing or by special investigations such as EEG, evoked potentials, and fMRI) [2].
The following is multiple choice question (with options) to answer.
What is the mildest type of brain injury? | [
"hydrocephalus",
"blunt trauma",
"concussion",
"dementia"
] | C | The mildest and most common type of brain injury is a concussion . This is a bruise on the surface of the brain. It may cause temporary problems such as headache, drowsiness, and confusion. Most concussions in young people occur when they are playing sports, especially contact sports like football. Other sports, like soccer, boxing, baseball, lacrosse, skateboarding, and hockey can also result in concussions. A concussion normally heals on its own in a few days. |
SciQ | SciQ-2218 | physical-chemistry, thermodynamics
Title: Temperature change in isobaric processes with and without change in number of molecules Hello I was thinking about two thermodynamics problems and I wanted to get some insights into how to solve them.
The first problem was: Suppose we have one mole of ideal gas under constant external pressure (1 atm) conditions, and let it conduct a reaction (for example a photoinduced isomerization) where there is no net change in number of molecules. This reaction for example has an enthalpy change which is not known. We can measure the total heat Q evolved due to the reaction (like in a constant pressure calorimeter).
So because there is no change of molecules this can be treated as a formal isobaric change (can it?). As enthalpy change is equal to heat Q in isobaric processes, we can say that the measured heat when reaction goes to completion is equal to the reaction enthalpy change, and therefore we can calculate the temperature change.
My doubt is: Is the work the system performs on its surroundings included in ΔH?
How can we determine the temperature change then if we have an reaction of the type:
Also at constant external pressure? Here, the particle number changes. When you measure the heat evolved in an isobaric calorimeter, it is assumed that the process takes place nearly isothermally (for the reaction mixture) and the heat involved is equal to the standard change in enthalpy $\Delta H^0$. Whether the total number of moles changes or not, $\Delta H^0$ includes the work done on the surroundings.
The following is multiple choice question (with options) to answer.
Isobaric expansion is a process occurring without a change in what? | [
"direction",
"temperature",
"pressure",
"energy"
] | C | isobaric expansion is a process occurring without a change in pressure. |
SciQ | SciQ-2219 | immunology, epidemiology, vaccination
Title: How does the immune system "learn" from a vaccine? According to Wikipedia:
A vaccine typically contains an agent that resembles a disease-causing
microorganism, and is often made from weakened or killed forms of the
microbe, its toxins or one of its surface proteins. The agent
stimulates the body's immune system to recognize the agent as foreign,
destroy it, and "remember" it, so that the immune system can more
easily recognize and destroy any of these microorganisms that it later
encounters. How does the immune system ""remember"" a foreign agent introduced via a vaccine? And how does it learn how to deal with subsequent encounters? Vaccines work by introducing an attenuated strain of the pathogen (or alternatively the antigens that are normally present on the pathogens surface) into the body, whereupon the body mounts an immune response. As this will (hopefully) be the first time that the body has encountered the antigens on the pseudo-pathogen's surface, the response is called the primary response.
This consists of two main divisions: the cell mediated pathway and the humoral pathway. In vaccination it is the humoral pathway that is important. This is where a division of white blood cells (B-Cells) produce antibodies that are complementary to the antigens on the pathogen surface, causing a negative effect to the pathogen (death, inability to reproduce, de-activation of toxins, etc.). However as each B-Cell produces a different antibody, there needs to be a mechanism to select the correct one:
Antigen Presentation (technically part of the cell-mediated-response) - a phagocyte engulfs the pathogen and displays the pathogenic antigens on its own surface.
Clonal Selection - B-Cells that are attracted to the invasion site attempt to bind their antibodies onto the pathogen's antigens. It takes time for this to occur successfully as you are essentially waiting for the correct mutation to happen.
Clonal Expansion - Once a complementary antibody producing B-Cell has been found it is then activated with the help of a T-Helper cell. This causes it to divide rapidly whereupon these cloned specific B cells can secrete their antibodies which will cause detriment to the pathogen.
The following is multiple choice question (with options) to answer.
What is the term for the process of exposing a person to a pathogen on purpose in order to develop immunity? | [
"vaccination",
"ramping",
"evacuation",
"priming"
] | A | Immunity can also be caused by vaccination. Vaccination is the process of exposing a person to a pathogen on purpose in order to develop immunity. In vaccination, a modified pathogen is usually injected under the skin by a shot. Only part of the pathogen is injected, or a weak or dead pathogen is used. It sounds dangerous, but the shot prepares your body for fighting the pathogen without causing the actual illness. Vaccination triggers an immune response against the injected antigen. The body prepares "memory" cells for use at a later time, in case the antigen is ever encountered again. Essentially, a vaccine imitates an infection, triggering an immune response, without making a person sick. |
SciQ | SciQ-2220 | gravity, fluid-dynamics, education, popular-science, bubbles
Now if the bubble becomes smaller, the air molecules will push it out again. If the bubble becomes bigger, the water molecules will push it in again. So the bubble can't change shape. You can see this in a balloon (thanks to Bobson). Take an empty balloon. It is very small because the rubber is pulling the balloon together, and there is no air in the balloon to push it out. Now if you inflate the balloon, more and more air will get inside. So the air will push out harder and harder, making the balloon bigger. If you poke the balloon, you can feel the air pushing against your finger. And if you take your finger away again, the air pushes the balloon back into shape. This is exactly the same as in a bubble. Except the water will 'break' much easier then the rubber in the balloon. So you can't really poke it.
So just like the die, the bubble and the balloon want to be in a specific shape. This means the bubble can only move as a whole. The die couldn't slide off your hand because of friction. With the bubble something similar is happening:
Hold your hands in a cup and throw some water in. Now open your hands. The water flowed off your hands, but some of the water is still sticking to your hand. This is because the molecules in the water and the molecules in your hand are pulling on each other too. It's called adhesion. Because of this adhesion between the water at the bottom of the bubble and your hand, the bubble can't slide off your hand, just like the die.
The following is multiple choice question (with options) to answer.
Why will water balloons launched into the air eventually burst? | [
"friction",
"momentum",
"heat",
"expansion"
] | D | Each day, hundreds of weather balloons are launched. Made of a synthetic rubber and carrying a box of instruments, the helium-filled balloon rises up into the sky. As it gains altitude, the atmospheric pressure becomes less and the balloon expands. At some point the balloon bursts due to the expansion, the instruments drop (aided by a parachute) to be retrieved and studied for information about the weather. |
SciQ | SciQ-2221 | planning, action-recognition, pddl
The approach used to solve this problem is to encode such knowledge in scripts, sequences of primitive acts. When triggered, eg by "Manuel went to a restaurant", this script is retrieved, and the following actions are looked for in the script. Anything that is recognised is used to fill gaps in the story, eg sitting down at a table, or looking at a menu. This was the task of the SAM program.
Basically you have a sequence of primitive actions, and you try to recognise a more abstract event "going to a restaurant" from that. Obviously you'd need to have a script to recognise, but one could presumably use this to derive a sequence of more generalised events, such as "retrieving an object from a high place", or "standing on top on another object".
The theory of using scripts, plans, and goals to describe human reasoning is detailed in Schank, Roger; Abelson, Robert P. (1977). Scripts, plans, goals and understanding: An inquiry into human knowledge structures. New Jersey: Erlbaum. ISBN 0-470-99033-3.
The following is multiple choice question (with options) to answer.
What type of behaviors do not have to be learned or practiced? | [
"diverse behaviors",
"acquired behaviors",
"innate behaviors",
"protective behaviors"
] | C | Innate behaviors do not have to be learned or practiced. |
SciQ | SciQ-2222 | paleoclimatology
Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes. This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.
The following is multiple choice question (with options) to answer.
Terrestrial biomes are classified by the climate and their what? | [
"geography",
"habitat",
"biodiversity",
"pollution"
] | C | Terrestrial biomes are classified by the climate and their biodiversity , especially the types of primary producers . The world map in Figure below shows where 13 major terrestrial biomes are found. |
SciQ | SciQ-2223 | organic-chemistry, acid-base, everyday-chemistry, photochemistry
Title: Chemical compounds responsible for the colors in flowers? I know that anthocyanins are a class of compounds responsible for the purple colors found in flower petals.
Anthocyanins (also anthocyans; from Greek: ἀνθός (anthos) = flower + κυανός (kyanos) = blue) are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. (same reference as above)
The anthocyanins, when extracted from flower petals with water, can be used as acid/base indicators, producing red colors in acid and blue in neutral solutions (in basic solutions they turn green, yellow, and then become colorless). When I've done the extractions, some red petals produce a red color in acid and maintain the red color at higher pH than purple flowers (see plate below), but some red flowers produce colors that seem to follow the normal progression.
Row 2 from the top was a purple flower, row 3 a red flower and row 4 also a red flower. (pH values start at 2 on the left and increase by 1 pH unit as you move right by adding the water extracts to buffer samples in the wells.)
So, are there other classes of compounds responsible for the red and yellow colors found in flowers? Can the red colors that give a "normal" anthocyanin pH response arise from pigments held in an acidic environment in the plant? (That may be a biology question, but I'm interested in the chemistry side of where the color comes from.)
are there other classes of compounds responsible for the red and yellow colors found in flowers?
Interest in colors, specifically dyes, was a real motivator for serious chemical work. Some of the early efforts were aiming to mimic Tyrian purple, also known as Royal Purple, because in antiquity it was worth its weight in gold.
Two classes of molecules come to mind other than anthocyanins in phytochemistry, such as the closely related flavones (its root means yellow) and the distinct carotenes (its root means carrot, but also responsible for flamingo color).
Can the red colors that give a "normal" anthocyanin pH response arise from pigments held in an acidic environment in the plant?
The following is multiple choice question (with options) to answer.
A flower's colors come from what part of the plant? | [
"vacuole",
"Petiole",
"Internode",
"glycogen"
] | A | Inside the plasma membrane of prokaryotic cells is the cytoplasm. It contains several structures, including ribosomes, a cytoskeleton, and genetic material. Ribosomes are sites where proteins are made. The cytoskeleton helps the cell keep its shape. The genetic material is usually a single loop of DNA. There may also be small, circular pieces of DNA, called plasmids . (see Figure below ). The cytoplasm may contain microcompartments as well. These are tiny structures enclosed by proteins. They contain enzymes and are involved in metabolic processes. |
SciQ | SciQ-2224 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
What stages in the life of a cell does the cell cycle include? | [
"intermediate stages",
"both",
"adult stages",
"all"
] | D | Cell division is just one stage of the cell cycle. The cell cycle includes all of the stages in the life of a cell. The cell cycle is more complex in eukaryotic than prokaryotic cells. |
SciQ | SciQ-2225 | cell-signaling, chemical-communication
Title: How many molecules are generally required for cell signallng processes for given cases? I know its really a broad topic but I am interested in just few cases:
Quorum sensing
neurotransmitters for the communication of images/ general information
hormones/pheromones
I actually want to know that does a single or hundreds of molecules are needed to communicate information from one cell to another.
I searched but approx number of molecules, I can't find anywhere. A cell can interact with other cells in zillions of ways. You can send information from one cell to other cells via neurotransmitters, hormones, pheromones, electric signals, magnetic resonance ,leukotrines etc.
In general a single type of molecule is enough to send such information. Like you require only Acetylcholine(Ach) as neurotransmitter to transmit various nerve impulses.
But, even for a single type, you require thousands of molecules. Like 1 molecule of Ach can do almost nothing and would immediately be broken by Acetylcholinesterase. You require 1000s of such molecules.
You can modify the communicating information via different types of transmitters. You can use GABA or glycine to supress any information exchange or use dopamine to enhance it. But again you will need many molecules of GABA or Glycine.
For visual pathway, you can use no. of types of transmitters like glutamate, glycine, gaba, dopamine, acetylcholine, substance P etc.
Neurotransmitters for visual pathway.
Hormones are transmitters that are required in small quantities. But, again you require certain concentration. There is normal blood concentration of various hormones like 80 pg/ml for calcitonin.
Quorum sensing use transmitters like AHLs. Again a certain threshold value is required for them to act.
Again, to produce these transmitters you have to go through a rigorous process of transcription, translation and post-translational modifications.
So, for cell to communicate a rigorous process is used.
The following is multiple choice question (with options) to answer.
What do you call the type of molecular signals that include insulin and that help regulate a number of biochemical processes? | [
"acids",
"enzymes",
"hormones",
"nerves"
] | C | Hormones – Hormones are molecular signals that help regulate a number of biochemical processes. Single amino acids and short protein chains are very common types of hormones. For example, insulin is a protein hormone that regulates the amount of glucose present in the bloodstream. |
SciQ | SciQ-2226 | electromagnetic-induction
Title: Working principle of inverter I got project on the working of inverter from school. I know this that DC inverter has an alternator switch which constantly changes its direction so that magnetic field is produced in primary coil due to which current is induced in secondary coil and we get output AC. So according to all this Electromagnetic induction should be the working principle behind the working of DC inverter. But DC can't take part in EMI, I know alternator is being used but it doesn't feels right. I hope I am right till this point I am taking following image as reference:
Please don't get mad at me if I got everything wrong. You are right. The alternator turns the DC of the battery into AC, which allows for changing magnetic fields in the primary. A transformer need a changing magnetic flux (which is why "DC doesn't work") - the alternating switch keeps changing the direction of the current, so the flux keeps changing. This induces e.m.f. in the secondary, and the result is an AC voltage on the output of the circuit.
The voltage wave form on the primary will be a square wave: the output waveform will be more complicated, depending on details of the resistance of the coils and the load. Obviously, the higher the switching frequency, the more regular the shape of the output: at very low frequencies, the output will "decay" between switching of the input alternator.
The following is multiple choice question (with options) to answer.
What type of device uses electromagnetic induction to change the voltage of electric current? | [
"mechanical transformer",
"electronic transformer",
"hot transformer",
"radioactive transformer"
] | B | An electric transformer is a device that uses electromagnetic induction to change the voltage of electric current. Electromagnetic induction is the process of generating current with a magnetic field. It occurs when a magnetic field and electric conductor, such as a coil of wire, move relative to one another. A transformer may either increase or decrease voltage. You can see the basic components of an electric transformer in the Figure below . For an animation showing how a transformer works, go to this URL: http://www. youtube. com/watch?v=VucsoEhB0NA . |
SciQ | SciQ-2227 | genetics, dna
Title: How do mutations come to be shared by all cells? It's my understanding that various hazards can damage the DNA in our cells, causing mutations.
But whenever I picture this, I see the damage being done to one of our tissues (for example, our lungs due to smoking, or our skin due to UV rays).
When I think about this, I see that... many cells in a smoker's lungs, or many cells on the back of a beach-goer's neck, may have mutations in their DNA. But only the cells in that tissue have these mutations... the other cells in our body would not have the same mutations.
In particular, sperm and egg cells would not have the same mutations, so the mutations due to smoking and UV rays shouldn't pass on to children.
Are there instances where mutations that occur over the course of our life are spread to every cell, including sperm and egg cells, so that every cell reflects the mutation, and the mutation is passed onto our offspring? Goods question! Only mutations that occurred when we were in the early stages of development will affect all cells. That's why pregnant mothers shouldn't smoke. The reason for this is that one cell goes on to divide and become all our cells so any mutations in that cell are passed on to cells formed when it divides. That same principle explains your smoker example. In the lung we have two types of cells which are called Type 1 and Type 2. Type 1 cells are constantly dying as they get old and they get replaced by type 2 cells whose job it is to divide continuously to replace Type 1 cells. So we have lots of type 1 and few type 2. When type 2 divide they make one type 1 cell and one type 2 cell, so type 2 cells never run out. If smoke causes a mutation in type 1 cells generally they're okay because they'll die before enough mutations occur. Of course something that causes lots of mutations could make it cancerous before it dies but that's rare. Now if it occurs in Type 2 cells every subsequent type 1 or type 2 cell that cell makes is mutated.
The following is multiple choice question (with options) to answer.
Mutations cannot be passed on to offspring if they occur in what type of cells? | [
"kept cells",
"blood cells",
"put cells",
"body cells"
] | D | Mutations that occur in body cells cannot be passed on to offspring. They are confined to just one cell and its daughter cells. These mutations may have little effect on an organism. |
SciQ | SciQ-2228 | atmosphere, ozone, topography
Title: What are the causes of lower UV radiation at lower elevations? After recently visiting the Dead Sea in Israel and not getting any skin burns, I was wondering about the reasons for that. Searching the literature, it seems that the UV radiation is indeed lower in the Dead Sea (ca. -400 m) compared to Beer Sheva (a nearby city at ca. +300 m): 1 2 3. Both UVA and UVB rays are lower, but UVB rays are attenuated the most.
These sources give mostly measurements, but hardly discuss the reasons for the lower radiation. I always thought that the ozone layer blocks most of the UV radiation, but here it seems that just a few hundred meters of atmosphere can greatly reduce the amount of incident UV.
What are the reasons for that? Is it simply because there are more air molecules that absorb the radiation? You are almost totally correct when you asked:
What are the reasons for that? Is it simply because there are more air molecules that absorb the radiation?
The Ozone Layer blocks most of UVB, but does not affect the amount UVA entering the atmosphere (as seen in the illustration below):
(Image source)
But there is a little more to it than that. From NASA's Earth Observatory's webpage What Determines How Much Ultraviolet Radiation Reaches the Earth’s Surface?, elevation's role in attenuating UVB (and by similar processes, UVA):
high elevations UV-B radiation travels through less atmosphere before it reaches the ground, and so it has fewer chances of encountering radiation-absorbing aerosols or chemical substances (such as ozone and sulfur dioxide) than it does at lower elevations.
The aerosols absorb and scatter incident UV radiation. So nearer to the surface, there is a greater concentration that the light must pass through - and as the altitude decreases, the UV radiation path is therefore increased, so the further 'down' in altitude, the more the air mass and an increased presence of aerosols absorb and scatter solar UV radiation.
In respect to the aerosols in area you have specified (the Dead Sea), according to the first link in your question, The Analysis of the Ultraviolet Radiation in the Dead Sea Basin, Israel (Kudish et al. 1997), they state
the air above the Dead Sea is characterized by a
relatively high aerosol content due to the very high salt content of the Dead Sea
Their results indicate that
The following is multiple choice question (with options) to answer.
What layer high in the atmosphere protects living things from most of the sun’s harmful uv rays? | [
"stratosphere",
"ozone layer",
"troposphere",
"Mesosphere"
] | B | Earth’s atmosphere is vital to life. The atmosphere provides the oxygen and carbon dioxide living things need for photosynthesis and respiration. Living things also need the ozone layer high in the atmosphere. Upper level ozone protects them from most of the Sun’s harmful UV rays. |
SciQ | SciQ-2229 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
What occurs over a large area when a rock is buried or compressed? | [
"regional metamorphism",
"metamorphic diffusion",
"landslide",
"cavern system"
] | A | Regional metamorphism occurs over a large area when a rock is buried or compressed. |
SciQ | SciQ-2230 | human-biology, evolution, reproduction, human-physiology, sexual-reproduction
Hypothesis 1: Profet (1993) hypothesized that shedding the endometrium may be an effective way to get rid of sperm-based pathogens. The accompanying bleeding, Profet hypothesizes, delivers immune cells into the uterine cavity that can combat pathogens.
Hypothesis 2: Strassmann (1996) surmises that the endometrial microvasculature is designed to provide the blood supply to the endometrium and the placenta, and that external bleeding appears to be a side effect of endometrial regression that arises when there is too much blood and other tissue for complete reabsorption. The relatively large blood loss as seen in humans and chimpanzees can be attributed to the large size of the uterus relative to adult female size and to the design of the microvasculature in the uterus wall.
References
- Crawford (ed), Handbook of Evolutionary Psychology: Ideas, Issues, and Applications, Psychology Press (1998)
- Profet, Quarterly Rev Biol (1993); 68(3): 355-86
- Strassmann, Quarterly Rev Biol (1996);71(2): 181-220
The following is multiple choice question (with options) to answer.
The uterus has an external opening known as what? | [
"cervix",
"vulva",
"fallopian tubes",
"ovaries"
] | B | Nervous system Most nematodes possess four longitudinal nerve cords that run along the length of the body in dorsal, ventral, and lateral positions. The ventral nerve cord is better developed than the dorsal or lateral cords. All nerve cords fuse at the anterior end, around the pharynx, to form head ganglia or the “brain” of the worm (which take the form of a ring around the pharynx) as well as at the posterior end to form the tail ganglia. In C. elegans, the nervous system accounts for nearly one-third of the total number of cells in the animal. Reproduction Nematodes employ a variety of reproductive strategies that range from monoecious to dioecious to parthenogenic, depending upon the species under consideration. elegans is a monoecious species and shows development of ova contained in a uterus as well as sperm contained in the spermatheca. The uterus has an external opening known as the vulva. The female genital pore is near the middle of the body, whereas the male’s is at the tip. Specialized structures at the tail of the male keep him in place while he deposits sperm with copulatory spicules. Fertilization is internal, and embryonic development starts very soon after fertilization. The embryo is released from the vulva during the gastrulation stage. The embryonic development stage lasts for 14 hours; development then continues through four successive larval stages with ecdysis between each stage—L1, L2, L3, and L4—ultimately leading to the development of a young male or female adult worm. Adverse environmental conditions like overcrowding and lack of food can result in the formation of an intermediate larval stage known as the dauer larva. |
SciQ | SciQ-2231 | botany, entomology
Title: What is this small white insect on my plants? Environment
I have a large amount of plants in an old industrial loft apartment.
I live in Rochester, New York.
I ship plants in from across the US, often exotic ones.
Observations
A few months ago, I noticed that two of my Sarracenia plants in my carnivorous plant bog were not growing anymore. Upon cutting them out as to not disrupt the live sphagnum moss grow medium, I noted that one of the insects in question had burrowed its way down into the core of the plant. I assume this to be the cause of the growing issue.
Today I noticed that one of my grape plants and Colocasia plants were covered in these bugs at different stages of growth. They range from white specs to ~3mm with the tail thing.
These insects appear sedentary. I have never seen one move, except when I cut the one out of the center of the plant.
Here is a picture of the bug, which was difficult to get due to the size.
Research
I looked through a variety of different "common insect" sites as well as some insect identification sites but I was unable to find anything remotely similar.
I have only elementary knowledge of insects. Any pointers in the right direction would be appreciated. Mealybug; don't know much about them.
The following is multiple choice question (with options) to answer.
Plants face two types of enemies: herbivores and what else? | [
"water",
"carnivores",
"pathogens",
"erosion"
] | C | Defense Responses against Herbivores and Pathogens Plants face two types of enemies: herbivores and pathogens. Herbivores both large and small use plants as food, and actively chew them. Pathogens are agents of disease. These infectious microorganisms, such as fungi, bacteria, and nematodes, live off of the plant and damage its tissues. Plants have developed a variety of strategies to discourage or kill attackers. The first line of defense in plants is an intact and impenetrable barrier. Bark and the waxy cuticle can protect against predators. Other adaptations against herbivory include thorns, which are modified branches, and spines, which are modified leaves. They discourage animals by causing physical damage and inducing rashes and allergic reactions. A plant’s exterior protection can be compromised by mechanical damage, which may provide an entry point for pathogens. If the first line of defense is breached, the plant must resort to a different set of defense mechanisms, such as toxins and enzymes. Secondary metabolites are compounds that are not directly derived from photosynthesis and are not necessary for respiration or plant growth and development. Many metabolites are toxic, and can even be lethal to animals that ingest them. Some metabolites are alkaloids, which discourage predators with noxious odors (such as the volatile oils of mint and sage) or repellent tastes (like the bitterness of quinine). Other alkaloids affect herbivores by causing either excessive stimulation. |
SciQ | SciQ-2232 | cellular-respiration, fermentation
Fermentation: An ATP-generating process in which organic compounds act as both donors and acceptors of electrons. Fermentation can take place in the absence of O2. Discovered by Louis Pasteur, who described fermentation as “la vie sans l’air” (“life without air”).
So the biochemical lawyers have produced a definition that very few readers will be able to take in at first sight. What is this business about electron donors and acceptors? Well what it means in relation to the fermentation process in which lactic acid is produced (note my legalistic choice of words) is that one organic compound is reduced (glyceraldehyde 3-phosphate) — by NAD+ — and one organic compound is oxidized (pyruvate) — by NADH. And as the production of ATP is included in the definition this means that Berg et al. include glycolysis in this definition of fermentation.
…except that on the same page there is the following statement:
pyruvate is converted, or fermented, into lactic acid in lactic acid fermentation or into ethanol in alcoholic fermentation
So here it seems that the word is being used for the conversion of pyruvate to lactate or ethanol, i.e. it excludes glycolysis.
Pasteur managed to talk about fermentation without being aware of glycolysis or ATP, and it is clear to me that you can write whatever carefully phrased definitions you like, but people are going to continue to use venerable terms like fermentation in whatever way seems natual to them.
The following is multiple choice question (with options) to answer.
What organism carries out only fermentation or anaerobic respiration? | [
"metabolites",
"aldehydes",
"aerobicc enzymes",
"obligate anaerobes"
] | D | |
SciQ | SciQ-2233 | ## 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 are the smallest type of blood vessel? | [
"spider veins",
"arteries",
"varicose veins",
"capillaries"
] | D | Further away from the heart, the aorta branches into smaller arteries, which eventually branch into capillaries. Capillaries are the smallest type of blood vessel; they connect very small arteries and veins. Gases and other substances are exchanged between cells and the blood across the very thin walls of capillaries. |
SciQ | SciQ-2234 | kinematics, ideal-gas
translational (move from one place to another => linear momentum)
rotational (turn around => angular momentum)
vibrational (oscillate)
This last one (vibrational modes) is probably the most complex, especially for large molecules with lots of bonds which can 'stretch, bend and twist'... but thats a topic for another question.
The 'ideal' gas which forms the basis of the kinetic gas theory ignores rotational and vibrational modes, which is usually valid for monatomic gases such as helium.
The following is multiple choice question (with options) to answer.
What type of behavior is most flexible? | [
"adaptation",
"innate behavior",
"reflex behavior",
"learned behavior"
] | D | Just about all human behaviors are learned. Learned behavior is behavior that occurs only after experience or practice. Learned behavior has an advantage over innate behavior : it is more flexible. Learned behavior can be changed if conditions change. For example, you probably know the route from your house to your school. Assume that you moved to a new house in a different place, so you had to take a different route to school. What if following the old route was an innate behavior? You would not be able to adapt. Fortunately, it is a learned behavior. You can learn the new route just as you learned the old one. |
SciQ | SciQ-2235 | water, molecular-structure, polarity, dipole
Now let's take water. The central atom (Oxygen) has a valence configuration of $2s^22p^4$, that is, 6 electrons. In water, since we have two single bonds, we have one $\sigma$ bond each (and no $\pi$ bonds). So we have total two $\sigma$ bonds.
But this leaves us with $6-2=4$ unpaired valence electrons. These form two "lone pairs" (pairs of electrons which do not bond). With two lone pairs and two $\sigma$ bonds, $x=4$. This gives us a tetrahedral structure (third in the balloon diagram). Two of the four points in the tetrahedron are occupied by the lone pairs, and two by bonds:
(Note that the angle 104.5 is not the same as the angle in perfect tetrahedra, 109.25--this is due to the lone pairs repelling each other)
So finally, we have the following "bent" structure for water:
From the structure, as shown above, it is very easy to check if the molecule has a dipole moment.
The following is multiple choice question (with options) to answer.
In the water molecule, two of the electron pairs are lone pairs rather than what? | [
"bonding ions",
"acid pairs",
"bonding pairs",
"ions pairs"
] | C | The water molecule, like the ammonia and methane molecules, has a tetrahedral domain geometry. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent . The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH 3 . |
SciQ | SciQ-2236 | food, nutrition, energy-metabolism
Title: What are the bare minimum nutrients required to survive as a human? I am trying to determine the bare minimum nutritional requirements to survive as a human, ignoring energy (caloric) requirements. Another way to ask this question is: What elements can humans not live without? I am not inquiring solely about what nutrients are needed, but also their approximate amounts.
Imagine pills that a person can take that covers all their base nutritional needs and that after taking this pill the person can eat whatever they want to meet their caloric requirements. Hypothetically, this pill could have some amount (how much?) fat, carbohydrates, protein, fiber, minerals, and vitamins, and the person could subsequently eat any other food to meet their caloric requirements knowing their nutritional needs would already be otherwise met. Lets ignore the possibility of the person suffering from health issues due to eating too much of any specific food to meet their caloric requirements (e.g., taking the magic pills and then eating only butter).
A person in this situation could think "Ok I've got most of my bases covered, now I just need to ingest another 1000 calories of (almost) anything I want).
What nutrients are absolutely necessary for humans to survive indefinitely, and how much of these nutrients are required?
I am hoping for a complete list with approximate amounts (e.g., 20g fat, 20g carbohydrates, 1mg Vitamin X, .05mg Vitamin Y, 10mg mineral X). Essential nutrients include (NutrientsReview):
Water
9 amino acids: histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, tryptophan, threonine, valine
2 fatty acids (alpha linolenic and linoleic acid)
Vitamins: A, B1, B2, B3, B5, B6, folic acid, biotin, B12, C,
D, E and K (and choline, which is considered a vitamin-like substance)
Minerals: calcium, chromium, chloride, copper, iodine, iron,
manganese, molybdenum, phosphorus, potassium, selenium, sodium, zinc
The following is multiple choice question (with options) to answer.
What are the basic building blocks of the human body? | [
"proteins",
"minerals",
"cells",
"vitamins"
] | C | The basic building blocks of the human body are cells. Human cells are organized into tissues, tissues are organized into organs, and organs are organized into organ systems. |
SciQ | SciQ-2237 | human-anatomy, muscles, human-evolution
Title: Are there genetic causes underlying the difference in circumference of the upper arm and foream? Is there any genetic reason for the difference in size between the upper arm and lower arm (i.e., the forearm)?
In most women, it seems that the upper arm is larger in circumference than the forearm. However, in males it seems to vary - some men (like myself) have an upper arm with a diameter smaller than their forearm, while for example in body builders the opposite may be true, as they often have large biceps. The first answer explains that proximal limb segments do more "work" * using quotes to be careful w.r.t. technical definitions of work. Genetically, this is correct--it's the ancestral condition for tetrapods. It is also worthwhile to answer why it's beneficial for why proximal segments get bulky to do this work, instead of their distal counterparts -- i.e. why did natural selection favor this arrangement in the first place.
There is a biomechanical reason for distal limb segments to be less massive than proximal limb segments, especially in tetrapods: That moving masses farther away from the center of rotation, when force is applied between the center of rotation and the mass, takes a LOT more force.
Let's consider the arm from your example. We'll treat the forearm as a "load" which is supported by the upper arm and shoulder.
In this case, the whole arm is a Type 3 lever, with the force applied (by upper arm and shoulder) inbetween the load center of mass and the fulcrum (joint). Image from https://alexeinstein.wordpress.com/2014/09/03/lever-of-human-body/:
In the picture, it's showing the hand (could be a weight in the hand, too) as the load, but for an empty hand the center of mass of the lower arm is probably slightly more proximal (but not more proximal than the muscle insertion).
In order to support the load that is the lower arm, the torques about the joint need to be balanced. So the torque produced by the muscles (by force AF in the diagram), needs to equal (or for bicep curls, exceed) the opposing torque produced by the mass of the load.
The following is multiple choice question (with options) to answer.
What is the medial bone of the forearm that runs parallel to the radius? | [
"fibula",
"radius",
"ulna",
"humerus"
] | C | Ulna The ulna is the medial bone of the forearm. It runs parallel to the radius, which is the lateral bone of the forearm (Figure 8.6). The proximal end of the ulna resembles a crescent wrench with its large, C-shaped trochlear notch. This region articulates with the trochlea of the humerus as part of the elbow joint. The inferior margin of the trochlear notch is formed by a prominent lip of bone called the coronoid process of the ulna. Just below this on the anterior ulna is a roughened area called the ulnar tuberosity. To the lateral side and slightly inferior to the trochlear notch is a small, smooth area called the radial notch of the ulna. This area is the site of articulation between the proximal radius and the ulna, forming the proximal radioulnar joint. The posterior and superior portions of the proximal ulna make up the olecranon process, which forms the bony tip of the elbow. |
SciQ | SciQ-2238 | evolution, taxonomy
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild.
That last part takes care of the ligers and tiglons. But what if we consider plants? Under the definition I just gave, most grasses (around 11,000 species) would have to be considered as one species. In the wild, most grasses will freely pollinate related species and produce hybrid seed, which germinates. You might then think we could just modify the definition to specify that the offspring must be fertile (i.e. able to reproduce with one another)...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild to produce fertile progeny.
Unfortunately, the situation is still more complicated (we've barely started!). Often wild hybridisation events between plants lead to healthy, fertile offspring. In fact common wheat (Triticum aestivum) is a natural hybrid between three related species of grass. The offspring are able to breed freely with one another.
Perhaps we could account for this by taking into account whether the populations usually interbreed, and whether they form distinct populations...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of populations or meta-populations of related individuals that resemble one another, are able to breed among themselves, but do tend not to breed freely with members of another species in the wild to produce fertile progeny.
The following is multiple choice question (with options) to answer.
The animal kingdom can also be divided into two basic groups, what are they? | [
"aquatic and land",
"invertebrates and vertebrates",
"sponges and vertebrates",
"mammals and fish"
] | B | The Animal Kingdom is one of four kingdoms in the Eukarya Domain. The Animal Kingdom, in turn, is divided into almost 40 modern phyla. The Animal Kingdom can also be divided into two basic groups: invertebrates and vertebrates. Most animal species are invertebrates, which lack a backbone. |
SciQ | SciQ-2239 | human-biology, microbiology
Title: How much weight/volume do microbes occupy within the human body? Microorganisms constitute the bulk of all the biomass on Earth. I weighed myself yesterday, and wondered how much less I would weigh if I were completely free of bacteria and microbes, inside and out.
Approximately how much weight and volume do microbes occupy within the average human body? How were these values obtained? @AlanBoyd's calculations are reasonable, I think the estimate is off though. The human microbome includes other bacteria which are not necessarily E.coli equivalent.
The human microbome projects give estimates that microbes are 1-3% total body mass. i.e. several pounds of bacteria.
The GI tract alone has most of the microbome mass - faeces is ~60% intestinal flora/fauna by dry weight, which for many adults alone must be hundreds of grams at any given moment.
The following is multiple choice question (with options) to answer.
These microorganisms are abundant in the human digestive track and serve many roles. what are they? | [
"tumors",
"bacteria",
"antioxidants",
"pathogens"
] | B | Bacteria provide vital ecosystem services. They are important decomposers. They are also needed for the carbon and nitrogen cycles. There are billions of bacteria inside the human intestines. They help digest food, make vitamins, and play other important roles. Humans also use bacteria in many other ways, including:. |
SciQ | SciQ-2240 | electromagnetism, charge, coulombs-law
Title: What is the force between a charged point and a charged 3d-object? If you have a sphere of radius $R$ with a uniformly distributed charge $Q$ on the surface and a point of charge $q$ with a distance to the center of the sphere on $d$, what would be the force experienced by the point charge? Would it be more correct to treat the sphere as a single point, using Coloumbs Law, or would it be more correct to use integrals to calculate the force from each 'point' on the sphere? For a general charge distribution the correct way is to use integrals to calculate the force from each point.
But a sphere uniformly charged is a special case, you can check with Gauss's law that it behaves just like a point charge in the center, so you can in this case use both ways: Coulomb's law (only in this special case) or integrals (always correct).
The following is multiple choice question (with options) to answer.
When both objects have a positive charge what will the force be between them? | [
"polar",
"attractive",
"repulsive",
"expressive"
] | C | The positive sign of the force indicates the force is repulsive. This makes sense, because both objects have a positive charge. |
SciQ | SciQ-2241 | fluid-dynamics, waves, geophysics
Title: What is the dominant cause for ocean waves at a beach? What is the dominant cause for ocean waves at a beach? Are they the result of wind/pressure difference? If so, the waves do seem to exist in similar intensity even during relative quiet times of the day.
Is there a simple mathematical model that we can quickly explain the intensity/frequency of waves with? Does the strength of the waves (say the variance and mean of the amplitude of waves) relate to a simple physical quantity (temperature, off shore wind, pressure difference)? Yes, primarily wind. It's called the Kelvin-Helmholtz instability. Strong winds in an area will excite a range of wavelengths, the longer wavelengths will go faster according to the deep water dispersion relation ( speed proportional to square root of wavelength). So if you see a train of waves with decreasing wavelength over time, you could in principle infer a common point of origin (this is a common textbook or qualifying exam type problem).
The following is multiple choice question (with options) to answer.
What are ocean waves mainly caused by? | [
"gravity",
"tides",
"humidity",
"wind"
] | D | Ocean waves are energy traveling through water. They are caused mainly by wind blowing over the water. |
SciQ | SciQ-2242 | life, extremophiles
Title: How close to Earth's core can organisms live? We don't to know much about organisms living deep below the Earth's crust. Recently a team led by S. Giovanni discovered some microbes 300 m below the ocean floor. The microbes were found to be a completley new and exotic species and apparently they feed off hydrocarbons like methane and benzene. Scientists speculate that life may exist in our Solar System far below the surface of some planets or moons. This raises some questions:
What is the theoretical minimum distance from Earth's core where life can still exist. Please explain how you came up with this number. For example, there are temperature-imposed limits on many biochemical processes.
Is there the potential to discover some truly alien life forms in the Earth's mantle (by this I mean, life which is not carbon based, or life which gets its energy in ways we have not seen before, or non DNA-based life, or something along these lines)?
What is the greatest distance below the Earth's crust that life has been discovered? I believe it is the 300 m I cited above, but I am not 100% sure. There's a lot we don't know about life in deep caves, but we can bound the deepest living organism to at least 3.5 kilometers down, and probably not more than 30 kilometers down.
The worms recovered from deep mining boreholes are not particularly specifically adapted to live that far down: they have similar oxygen/temperature requirements as surface nematodes.
The Tau Tona mine is about 3.5 kilometers deep and about 60˚ C at the bottom. Hydrothermal vent life does just fine up to about 80˚C, and the crust gets warmer at "about" 25˚C per kilometer. It's entirely reasonable to expect life to about 5 kilometers down, but further than that is speculation.
Increasing pressure helps to stabilize biological molecules that would otherwise disintegrate at those temperatures, so it's not impossible there could be life even deeper. It may even be likely, given that the Tau Tona life breathes oxygen.
I am certain no life we might recognize as life exists in the upper mantle.
The following is multiple choice question (with options) to answer.
What type of archaea live in salty environments? | [
"amphibians",
"halophiles",
"sporozoans",
"arthropods"
] | B | Archaea that live in salty environments are known as halophiles. |
SciQ | SciQ-2243 | conventions, dimensional-analysis, si-units, metrology
Title: Fundamental quantities in physics I observed that the fundamental units like meter, kilogram, ampere, kelvin and candela are all indirectly dependent on one single fundamental value 'second' and each other.
For example:
Meter:-
1 meter is the length that makes the speed of light in vacuum to be 299792458 when expressed in $\rm m\,s^{-1}$, where the second is defined in the terms of ground state hyperfine transition frequency of Cs 133
Here, Meter is indirectly dependent on second and does not really standout as a fundamental unit to me. Can anyone clarify on how it is a fundamental quantity? As already pointed out by the quote in your questions the SI-Units are nowadays defined by fixing physical constants in order to avoid artifacts due to the reliance on real-world physical samples. For example, keeping a meter e.g. as some rod that is "one meter long" is imprecise as there are always measurement errors on the measurements of the rod and the rod could change its shape with time (e.g. through corrosion, etc.).
Now your question is what classifies the meter as a fundamental unit. The short answer is nothing. As already demonstrated within your question you could as well define the velocity to be "fundamental" and derive length from the fundamental "velocity" unit and the "time" unit.
This counts for all the SI-Units, the important thing is that you need a set of units by which you can express all other units.
In terms of the current SI-Units, you can write the unit $[Q]$ of every physical quantity $Q$ in terms of the SI-Units (m, s, kg, A, K, mol, cd)
$$[Q]=\text{m}^\alpha\ \text{s}^\beta\ \text{kg}^\gamma\ \text{A}^\delta\ \text{K}^\epsilon\ \text{mol}^\zeta\ \text{cd}^\eta\ $$
with $\alpha,\beta,\gamma,\delta,\epsilon,\zeta,\eta\in\mathbb{Z}$.
It is now convention that we say we use the length instead of the velocity as a fundamental unit.
The following is multiple choice question (with options) to answer.
What can be thought of as the fundamental unit of life? | [
"cell",
"ion",
"atom",
"electron"
] | A | It could easily be said that a cell is the fundamental unit of life, the smallest unit capable of life or the structural and functional unit necessary for life. But whatever it is, a cell is necessary for life. The Cell Biology chapter will discuss some of the fundamental properties of the cell, with lessons that include the cell structure, transport in and out of the cell, energy metabolism, and cell division and reproduction. |
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