source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3444 | atomic-physics
Title: What gives covalent bond its strength? I came across the following passage from Structure and Properties chapter of Morrison-Boyd Organic Chemistry:
What gives the covalent bond its strength? It is the increase in electrostatic attraction. In the isolated atoms, each electron is attracted by-and attracts-one positive nucleus;in the molecule, each electron is attracted by two positive nuclei.
However, I don't think it refers to the force holding each atom together. It rather, merely describes the increase in the electrostatic force of attraction between the electrons and the nuclei. I believe that bond strength is a measure of the difficulty in pulling apart the component atoms, not the electrons from the positive nuclei.
What exactly is the pattern or picture of the forces on the nuclei and the electrons, due to one another, that holds the component atoms together? (I am aware that the decrease in overall energy or increase in stability is definitely not a reason to account for the strength of covalent bond, but rather a consequence of the action of such forces.) It probably helps to define what a covalent bond really is. Covalent bonds occur when one or more Atomic Orbitals (AO) of the participating atoms constructively interact and form a (bonding) Molecular Orbital (MO). The figure below schematises the formation of a $\sigma_{ss}$ MO when two hydrogen atoms combine to form a dihydrogen molecule:
The following is multiple choice question (with options) to answer.
What do covalent bonds give atoms a more stable arrangement of? | [
"electrons",
"cell walls",
"protons",
"neutrons"
] | A | Covalent bonds form because they give atoms a more stable arrangement of electrons. Look at the oxygen atoms in the Figure above . Alone, each oxygen atom has six valence electrons. By sharing two pairs of valence electrons, each oxygen atom has a total of eight valence electrons. This fills its outer energy level, giving it the most stable arrangement of electrons. The shared electrons are attracted to both oxygen nuclei, and this force of attraction holds the two atoms together in the oxygen molecule. |
SciQ | SciQ-3445 | genetics, immunology, ecology, biodiversity, fitness
Title: What does genetic diversity in one species have to do with survival rate when an epidemic spreads? I was studying about genes, and soon remembered that the more diverse the genetics of one species, the less the chance of the species to go extinct from natural disaster.
One instance was an epidemic spreads.I don't fully understand why that happens, so I searched for it in Google and books, but all of them only told me that it is true, not why or how.
So my question is : why and how genetic diversity in one species affects the chance of the species's extinction?
I mean, for example, does it relate to antibodies or something else? Genetic diversity could be understood as a variation in alleles (gene variants) and their frequencies in a population. Due to these allelic variations, we would expect an inherent variability in individual genotypes (or genetic codes). Phenotypes (or traits) can and do vary with changes in underlying genotype. (In simple terms: if you change the underlying genetic code, it could result in changes to an individual's traits).
Changes in traits (e.g., color, size, speed, temperature regulation, mobility, etc.) could lead to a variation in energy conservation, survival, reproductive success, and ultimately fitness.
If any member of a population is more fit given a set of environmental circumstances, it is morel likely that they will survive and pass on their genes to subsequent generations.
You would benefit from reviewing evolution and natural selection. (Sexual selection and genetic drift are relevant, too, of course).
However, the environment and resulting ecologies are always changing, and so there is never an "endpoint" of this process. I.e., there's never a perfectly fit individual that will survive all future environmental changes better than all other variants. In fact, all organisms can only tolerate stressful environmental conditions to a point. (See, e.g., principle of allocation).
As a result, any given individual is limited in its ability to survive various environmental conditions, and no individual organism can survive all possible environmental conditions.
The following is multiple choice question (with options) to answer.
What is the most important process for the survival of a species? | [
"reproduction",
"differentiation",
"digestion",
"metabolism"
] | A | |
SciQ | SciQ-3446 | biochemistry, physiology
Title: Organism with the greatest amount of gold as percentage of body mass I've read that the human body contains trace amounts of gold:
http://www.tellmehowmuch.net/how-much-gold-is-found-in-the-human-body.html
http://web2.airmail.net/uthman/elements_of_body.html
Are there other species that are known to have significantly higher ratios of gold to body mass?
And while there seems to be no definitive answer about the benefit of gold being in the human body, are there any species for which gold has demonstrative bodily uses or benefits? Acidothiobacillus ferrooxidans can gain metabolic energy by utilizing gold thiosulphate complexes (Reith et al., 2007); Micrococcus luteus can oxidize methane to methanol using gold-containing enzyme (Levchenko et al., 2002).
However, for most organisms, gold is toxic (Wietkiewicz & Shaw, 1981); some bacteria actively detoxify gold: Cupriavidus (Ralstonia, Wautersia) metallidurans, Desulfotomaculum sp., Desulfovibrio sp., Hyphomonas adhaerens, Plectonema boryanum, Pseudomonas aeruginosa Salmonella enterica, Shewanella algae, Spirulina platensis (Reith et al., 2007).
Reith F, Lengke MF, Falconer D, Craw D, Southam G (2007) The geomicrobiology of gold. ISME J. 1: 567-584.
Levchenko LA, Sadkov AP, Lariontseva NV, Koldasheva EM, Shilova AK, Shilov AE. (2002) Gold helps bacteria to oxidize methane. J Inorg Biochem 88: 251-253.
Witkiewicz PL & Shaw CF III (1981) Oxidative cleavage of peptide and protein disulphide bonds by gold(III): a mechanism for gold toxicity. J Chem Soc Chem Commun 21: 1111–1114.
The following is multiple choice question (with options) to answer.
Which common element is the most found in living organisms? | [
"carbon",
"hydrogen",
"monoxide",
"oxygen"
] | A | Carbon is one of the most common elements found in living organisms. Chains of carbon molecules form the backbones of many organic molecules, such as carbohydrates, proteins, and lipids. Carbon is constantly cycling between living organisms and the atmosphere ( Figure below ). The cycling of carbon occurs through the carbon cycle . |
SciQ | SciQ-3447 | biochemistry, molecular-biology, cell-biology, physiology
Title: Which organelle synthesizes glycogen phosphorylase and why? I know that glycogen phosphorylase is not synthesized in the rough endoplasmic reticulum of liver cells, unlike many other proteins such as insulin receptor, lysosomal enzyme and serum albumin. I would like to know the organelle where glycogen phosphorylase is made and why it is made there. Protein translation occurs via ribosomes bound to strands of messenger RNA in the cytoplasm; these structures are called polysomes but don't have a membrane surrounding them so you might not want to call them organelles. Polysomes making proteins destined for secretion, for the plasma membrane, or for some organelles (like your examples) are directed to the endoplasmic reticulum via a signal peptide typically near the beginning of the translated sequence. The combination of polysomes and endoplasmic reticulum is what is called rough endoplasmic reticulum. See this Wikipedia page for a more complete explanation of how particular proteins are targeted to their correct locations.
The following is multiple choice question (with options) to answer.
What are the organelles on which proteins are made during protein synthesis called? | [
"lysosomes",
"ribosomes",
"mitochondria",
"fibroblasts"
] | B | Ribosomes are the organelles on which proteins are made during protein synthesis . Ribosomes are found throughout the cytosol of the cell and attached to the endoplasmic reticulum organelle. Ribosomes order amino acids using messenger RNA (mRNA) as a template in a process called translation. Ribosomes are made from complexes of ribosomal RNAs (rRNA) and proteins called ribonucleoproteins . Each ribosome is divided into two subunits. The smaller subunit binds to the mRNA pattern, while the larger subunit binds to the transfer RNA (tRNA) and the growing polypeptide chain. More about the ribosome will be discussed in the Cell Structures: Ribosomes (Advanced) concept. |
SciQ | SciQ-3448 | gravity, energy, mass, mass-energy
Title: How does energy convert to matter? To my understanding, matter and energy are one and the same. Shifting from $E$ to $M$ in Einstein's famous equation requires only a large negative acceleration. If $M$ really is $E/c^2$, does that make matter the solid state of energy? I've read a lot about positron-electron collisions at high energies creating larger particles, and there is obvious matter conversion in fusion and fission reactions, but I can't find anything describing the physics of the conversion from energy to matter, rather than the interactions of what is already matter.
Specifically, the thing I'm getting hung up on is the reason energy would take on a solid state in the first place. If energy is represented by waves, how does it become particles? If gravity is determined by mass, and mass is nothing more than static energy, does that make gravity a static-electromagnetic force? Energy and matter are not the same. Matter is a type of thing, whereas energy is a property of a thing, like velocity or volume. So your premise is flawed. In particular:
there's no such thing as "a solid state of energy" - hopefully it makes sense that a property of something does not have states
energy is not represented by waves, though it is a property of a wave. It's also a property of a particle (which, in quantum field theory, is really just a tightly bunched wave).
Note that mass can be converted to energy, because mass actually is energy. It is one of various types of energy: kinetic energy, potential energy, mass energy, and so on. Different types of energy get converted into each other all the time.
I'd suggest looking at several of the questions under the "Related" heading at the right for more information about this. (I actually thought this had been asked here before, but I didn't find an exact duplicate.)
The following is multiple choice question (with options) to answer.
Chemistry is the study of matter and energy and how they what? | [
"interaction",
"distinct",
"division",
"interact"
] | D | Chemistry is the study of matter and energy and how they interact, mainly at the level of atoms and molecules. Basic concepts in chemistry include chemicals and chemical reactions. |
SciQ | SciQ-3449 | genetics, evolution, population-genetics, population-biology, allele
Title: Relationship between genetic diversity within and between species Here is a quote from Wagner (2008)
A second line of evidence [against neutralism] comes from the relationship between the mean number of polymorphic differences between alleles within a species, $\pi$, and the number of fixed differences between genes in two species, $d$. For neutral mutations, a positive association between $\pi$ and $d$ should exist, because the neutral theory predicts that both quantities are linearly proportional to the rate at which neutral mutations arise. Recent genome-scale data shows instead that this association is in fact negative.
What do "the mean number of polymorphic differences between alleles within a species" and "the number of fixed differences between genes in two species" have to do with each other? Why should there be any relationship at all? And by "two species", are they talking about Eastern Yellowback Whooping Finches versus Western Yellowback Whooping Finches, or any arbitrary two species, like E. Coli versus Muskrats?
I found this related question, but it doesn't say anything about different species. Metrics of interest
The two metrics you are interested in are
$\pi$ - the mean number of differences between two randomly sampled (with replacement) alleles in a population
$d$ - the mean number of differences between two randomly sampled (with replacement) alleles coming from two different species
Consider two sequences
ATCGTCAAT
ATAGTTAAT
There are 2 pairwise differences between these two sequences (positions 3 and 6).
The whole point here is to understand that two individuals in the same population coalesce at a given time in the past just like two individuals coming from two different species. The number of pairwise differences is just equal to the rate at which mutations accumulate multiplied by the coalescence time. Let me develop this idea with a few equations below.
Neutral Expectations
Let's do the math! We will do two important assumptions below.
Every mutation makes a new allele (it is an infinite allele model)
All mutations are substitutions (no indels, no gene duplication, etc...)
The following is multiple choice question (with options) to answer.
What is the term for the relationship in which one species benefits while the other species is harmed? | [
"parasitic relationship",
"combative relationship",
"commensal relationship",
"symbiotic relationship"
] | D | symbiotic relationship in which one species benefits while the other species is harmed. |
SciQ | SciQ-3450 | cell-biology, neuroscience, histology
Although the paper mainly talks of the sorting of axonal and somatodendritic vesicles as seen in the picture, they also seem to apply for the RER which actually are the basis for Nissl's granules.
This structure excludes not only somatodendritic vesicles but also larger organelles, such as the Golgi complex and the rough ER, in effect constituting the cytoplasmic boundary for the somatodendritic and axonal domains..... The exclusion of the rough ER and Golgi complex, in addition to somatodendritic vesicles, at the PAEZ suggests that a common restriction mechanism may operate for all of these organelles.
Well, as you might have understood by now, it's not a matter of the size of the axon/ dendrite since same sized vesicles are being diverted in either direction and as previously mentioned, even mitochondria enter the axon.
The following is multiple choice question (with options) to answer.
Transport vesicles move what type of molecules from the rough endoplasmic reticulum to the golgi apparatus? | [
"proteins",
"acids",
"hormones",
"lipids"
] | A | Transport vesicles are part of the endomembrane system. They are able to move molecules such as proteins between locations inside the cell. For example, transport vesicles move proteins from the rough endoplasmic reticulum to the Golgi apparatus. |
SciQ | SciQ-3451 | zoology, ichthyology, marine-biology
Switek goes on to to talk about exceptions in some marine mammals:
At this point some of you might raise the point that living pinnipeds like seals and sea lions move in a side-to-side motion underwater. That may be true on a superficial level, but pinnipeds primarily use their modified limbs (hindlimbs in seals and forelimbs in sea lions) to move through the water; they aren’t relying on propulsion from a large fluke or caudal fin providing most of the propulsion with the front fins/limbs providing lift and allowing for change in direction. This diversity of strategies in living marine mammals suggests differing situations encountered by differing ancestors with their own suites of characteristics, but in the case of whales it seems that their ancestors were best fitted to move by undulating their spinal column and using their limbs to provide some extra propulsion/direction.
The following is multiple choice question (with options) to answer.
Fish use some of their fins to propel themselves through the water and others to do what? | [
"breathe",
"steer",
"rest",
"reproduce"
] | B | Most fish have several fins for swimming. They use some of their fins to propel themselves through the water and others to steer the body as they swim. |
SciQ | SciQ-3452 | 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.
This series of life stages and events that a sexually reproducing organism goes through is called its what? | [
"formative period",
"life cycle",
"development cycle",
"maturation cycle"
] | B | Sexual reproduction occurs in a cycle. Diploid parents produce haploid gametes that unite and develop into diploid adults, which repeat the cycle. This series of life stages and events that a sexually reproducing organism goes through is called its life cycle . Sexually reproducing organisms can have different types of life cycles. Three are described in the following sections. |
SciQ | SciQ-3453 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
What are small gnawing mammals such as rats and mice called? | [
"marsupials",
"furries",
"rodents",
"miniatures"
] | C | Rodents include rats, mice, and other small gnawing mammals. They have a single pair of continuously growing incisors (teeth) in each of the upper and lower jaws that must be kept short by gnawing. |
SciQ | SciQ-3454 | interference, huygens-principle
Is the new wavefront formed by the interference of these secondary wavelets?
If so, then how can a light source have uniform intensity if there is constructive and destructive interference happening during the light's propagation?
(See image)
(Note: This image was downloaded from the internet. The yellow boxed portions, the black arrows that point to it and the write- up near the arrows illustrate my doubt. The rest of the write- up came along with the downloaded image.)
That is, in both cases, the waves interfere. But, in the propagation of a plane wavefront (according to Huygens Principle), the resultant wave (formed by the interference of secondary wavelets) has uniform intensity. Whereas, the intensity of the resultant wave in the image on the right, is not uniform. Why? There is a key difference between the two cases, and you have to consider the phase of each wavelet. "Wavefronts" that create a double-slit interference pattern come only from the two slits. When the two spherical waves (wavelets) reach a point $P$ on the screen they have each picked up a phase proportional to the distance between $P$ and their slit, and the resultant amplitude at $P$ will depend on the difference between the two phases.
Now, for the propagating plane wave each point on the wavefront creates a wavelet, and each wavelet may contribute at a point $P$ (you may picture this as being equivalent to "placing a slit at each point on the wavefront"). Now you see that problem is harder, since we have to add up all the (infinite) contributions from the wavelets to find the amplitude at $P$! Fortunately, for points on the wavefront far from the projection of $P$ the phase picked up during propagation will be wildly different (since the distance traveled is considerably big), and because of this there's a tendency for mutual cancelation of these wavelets. Therefore only the wavelets created "near" the projection of $P$ contribute significantly, and since they were created near each other their phase will not change too much and they'll add up constructively at $P$.
To actually calculate and verify that the amplitude is the same is better to use directly the formal treatment of waves through a wave equation though.
The following is multiple choice question (with options) to answer.
Dutch scientist christiaan huygens' principle of what states that every point on a wavefront is a source of wavelets that spread out in the forward direction at the speed of the wave itself? | [
"wave propagation",
"wave dynamics",
"electromagnetic dynamics",
"energy propagation"
] | A | The Dutch scientist Christiaan Huygens (1629–1695) developed a useful technique for determining in detail how and where waves propagate. Starting from some known position, Huygens’s principle states that: Every point on a wavefront is a source of wavelets that spread out in the forward direction at the same speed as the wave itself. The new wavefront is a line tangent to all of the wavelets. Figure 27.5 shows how Huygens’s principle is applied. A wavefront is the long edge that moves, for example, the crest or the trough. Each point on the wavefront emits a semicircular wave that moves at the propagation speed v . These are drawn at a time t later, so that they have moved a distance s = vt . The new wavefront is a line tangent to the wavelets and is where we would expect the wave to be a time t later. Huygens’s principle works for all types of waves, including water waves, sound waves, and light waves. We will find it useful not only in describing how light waves propagate, but also in explaining the laws of reflection and refraction. In addition, we will see that Huygens’s principle tells us how and where light rays interfere. |
SciQ | SciQ-3455 | earth, satellites
Title: how far away can something be from the earth and still be in orbit? Just as the title asks,
How far away can, say, a satellite be and still be in "orbit" ?
How about for a given velocity?
Fun Facts
200 miles (320 km) up is about the minimum to avoid atmospheric interference. The Hubble space telescope orbits at an altitude of 380 miles (600 km) or so.
potentially helpful numbers
mass of Earth = 5.97219 × 1024 kilograms
mass of the Moon = 7.34767309 × 1022 kilograms
distance (earth, moon) = 238,900 miles (384,400 km) In the restricted three body problem, where you consider two objects orbiting each other, such as the sun and earth, and the motion of a third object that does not affect the movement of the first two, but is affected by their gravity, you can sort of figure out how far/fast from one object you have to be to not be orbiting it anymore.
The picture above is taken from Shane D. Ross' Ph.D. thesis. Depending on the total energy of the third mass, it will never be able to go into the shaded areas. So if you are orbiting Earth, which would be $m_2$ in the Sun-Earth example, or $m_1$ in an Earth-Moon one, there is a minimum energy at which can break out of the first and start orbiting the other body. The transition point is the Lagrangian point $L_1$. At a higher energy, it is possible to break away to infinity from both objects, the transition point corresponding to the Lagrangian point $L_2$.
So depending on a more precise definition of you question, a possible answer is that a satellite beyond the Sun-Earth L1 point is more orbiting the Sun than the Earth. The Sun-Earth L1 point is, according to this, about 1% of the way to the Sun. So that's about 1,500,000 Km. You could of course calculate the corresponding $E_1$ enery and translate that to kinetic energy and velocity.
The following is multiple choice question (with options) to answer.
Orbiting at a fairly typical 370 kilometers, the international space station is an example of what? | [
"flagella satellite",
"alteration satellite",
"manmade satellite",
"high orbit satellite"
] | C | We commonly talk about satellites orbiting Earth. But what does that really mean? When a satellite, space shuttle, or some other object is orbiting a planet, it maintains a circular orbit around the planet a constant distance off the surface. Manmade satellites typically orbit between 200 and 400 miles. For example, the International Space Station (ISS) orbits at 370 km, or 230 miles. |
SciQ | SciQ-3456 | botany, plant-physiology, reproduction, plant-anatomy, life-history
In dimorphic cleistogamy CL and CH flower differ in the time or place
of production, with CL flowers produced in conditions (underground,
low light levels, early in the season) that are potentially
unfavorable for outcrossing.
In induced cleistogamy potentially CH flowers that experience conditions such as drought or low temperatures fail to open and self-pollinate, becoming, in effect, CL flowers.
You should check out the Culley and Klooster (available online if you make a jstor login) – they discuss complete cleistogamy which addresses your last question. They report several completely CL species in their Table 1, and give references.
More generally, many different plant groups maintain balances of self-pollination and outcrossing (i.e. "real sex"), through an even more diverse set of mechanisms.
Even more generally, many plants and some animals maintain balances of sexual reproduction and clonal reproduction, through an even more diverse set of mechanisms. For instance, vegetative reproduction (e.g., strawberry runners) is very common in many plant groups; facultative and obligate parthenogenesis in animals also occurs.
Culley, Theresa M. and Matthew R. Klooster (2007). The Cleistogamous Breeding System: A Review of Its Frequency, Evolution, and Ecology in Angiosperms. Botanical Review. Vol. 73, No. 1, pp. 1-30
The following is multiple choice question (with options) to answer.
When plant type alternates from generation to generation what is this called? | [
"change in generation",
"alternation of generation",
"turbidity of generation",
"differentiation of generation"
] | B | Plants alternate between diploid-cell plants and haploid-cell plants. This is called alternation of generations , because the plant type alternates from generation to generation. In alternation of generations, the plant alternates between a sporophyte that has diploid cells and a gametophyte that has haploid cells. |
SciQ | SciQ-3457 | endocrinology, glucose, homeostasis, insulin, hypothalamus
Title: Role of the Hypothalmus in the control of Blood Sugar In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process? Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
The following is multiple choice question (with options) to answer.
Which type of diabetes involves the pancreas not secreting enough insulin, which causes high levels of glucose in the blood? | [
"type 2",
"type 1",
"type 3",
"non typical"
] | B | Endocrine system disorders usually involve the secretion of too much or not enough hormone. For example, a tumor of the adrenal gland may lead to excessive secretion of growth hormone, which causes gigantism. In Type 1 diabetes, the pancreas does not secrete enough insulin, which causes high levels of glucose in the blood. |
SciQ | SciQ-3458 | inorganic-chemistry, coordination-compounds, oxidation-state
Later transition metals, which have lower maximum oxidation states due to increased electronegativity/ionization energy, have more $d$ electrons coming from the cationic shells and thus are no longer so stabilized by $\pi$ back-donation. Then the fluoro complexes, with a relatively $\pi$-inactive ligand, take over. In the $3d$ series cobalt, cited above as forming an oxide complex with the formula $\ce{[CoO4]^{3-}}$, also forms a +4 fluoride complex $\ce{[CoF6]^{2-}}$(1). Fluoride complexes are also seen with both nickel and copper in oxidation states above $+2$, including the $\ce{[NiF6]^{2-}}$ ion mentioned in this question and the copper(III) species $\ce{[CuF6]^{3-}}$. Zinc in the $3d$ series is limited to oxidation states of $+2$ or less, but if mercury has a tetrafluoride $\ce{HgF4}$ (disputed), it's no coincidence that this too is a fluoride.
Reference
The following is multiple choice question (with options) to answer.
Halides of the transition metals become more covalent with increasing oxidation state and are more prone to what? | [
"cycloaddition",
"hydrolysis",
"comproportionation",
"decarbonylation"
] | B | Transition-metal fluorides usually have higher oxidation states than their iodides. For a given metal, the lowest-oxidation-state oxide is basic and the highest-oxidation-state oxide is acidic. Halides of the transition metals become more covalent with increasing oxidation state and are more prone to hydrolysis. Propose a method to prepare each of the following compounds: TiCl 4[(CH3)2O]2, Na2TiO3, V2O5, and Na2Cr2O7. Of the group 5 elements, which. |
SciQ | SciQ-3459 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Dense connective tissue contains more collagen fibers than does loose connective tissue. as a consequence, it displays greater resistance to what? | [
"stretching",
"stiffening",
"contracting",
"freezing"
] | A | Dense Connective Tissue Dense connective tissue contains more collagen fibers than does loose connective tissue. As a consequence, it displays greater resistance to stretching. There are two major categories of dense connective tissue: regular and irregular. Dense regular connective tissue fibers are parallel to each other, enhancing tensile strength and resistance to stretching in the direction of the fiber orientations. Ligaments and tendons are made of dense regular connective tissue, but in ligaments not all fibers are parallel. Dense regular elastic tissue contains elastin fibers in addition to collagen fibers, which allows the ligament to return to its original length after stretching. The ligaments in the vocal folds and between the vertebrae in the vertebral column are elastic. In dense irregular connective tissue, the direction of fibers is random. This arrangement gives the tissue greater strength in all directions and less strength in one particular direction. In some tissues, fibers crisscross and form a mesh. In other tissues, stretching in several directions is achieved by alternating layers where fibers run in the same orientation in each layer, and it is the layers themselves that are stacked at an angle. The dermis of the skin is an example of dense irregular connective tissue rich in collagen fibers. Dense irregular elastic tissues give arterial walls the strength and the ability to regain original shape after stretching (Figure 4.15). |
SciQ | SciQ-3460 | newtonian-mechanics, forces, everyday-life
Title: Proof that the ground pushes you up It has been said that when you try to jump you are exerting your force on the ground and the ground pushes you up. I was wondering if this was an over-simplification or not. If so, what's the full explanation? Otherwise, I would like to know the derivation of this proof.
For clarification: If I jump and the ground is "pushing me up" (from a normal force), then assuming that this is not a simplification and is truly what happens, why is this true? My current hypothesis is that it has something to deal with electromagnetism (pushing two repelling magnets together; how atoms swerve to avoid collisions, for example). If you try jumping on a trampoline, you will notice that when you jump up, the trampoline bends and stretches underneath you. It stretches some even if you stand still, but it stretches extra when you jump.
The trampoline is elastic. When it's stretched, you can feel it pulling back towards its normal shape. Thus, just before you jumped, the trampoline was extra stretched and exerted extra force on you, and this is why you went up in the air.
A similar thing happens when you stand on other surfaces, except that the stretching is very minor and we don't usually observe it. When you jump, your legs exert extra force on the ground. That compresses the ground, making it act like a spring. Being stretched further than normal, it exerts a larger-than-normal force on you, and you shoot up into the air. If you stood on a weak table or a thin sheet of ice, it might be strong enough to hold you as you stand still, but when you go to jump, the extra stretching might be too much and break it.
It is not really necessary that the ground act like a spring; this is just what I thought would be easiest to visualize. In fact you could push off water in a fairly similar way. All that matters is that the thing you push off has inertia, so that when you exert a force on it, it also exerts a force on you.
The following is multiple choice question (with options) to answer.
What does pushing an object over the surface of a ramp cause? | [
"friction",
"vibration",
"tension",
"Acceleration"
] | A | Consider the ramp in Figure below . It’s easier to push the heavy piece of furniture up the ramp to the truck than to lift it straight up off the ground. However, pushing the furniture over the surface of the ramp creates a lot of friction. Some of the force applied to moving the furniture must be used to overcome the friction. It would be more efficient to use a dolly on wheels to roll the furniture up the ramp. That’s because rolling friction is much less than sliding friction. As a result, the efficiency of the ramp would be greater with a dolly. |
SciQ | SciQ-3461 | botany, plant-physiology, ecology, virology, host-pathogen-interaction
Note about symbiosis - comes in reaction to @Gerhard's comment
Different authors use the word symbiosis differently. From wikipedia:
The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).4 After 130+ years of debate,5 current biology and ecology textbooks now use the latter "de Bary" definition or an even broader definition (i.e. symbiosis = all species interactions), with the restrictive definition no longer used (i.e. symbiosis = mutualism)
The following is multiple choice question (with options) to answer.
Parasitism, mutualism, and commensalism are all examples of what type of biological relationship? | [
"reproduction",
"adaptation",
"evolution",
"symbiosis"
] | D | |
SciQ | SciQ-3462 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
What occurs when substances move from areas of lower to higher concentration or when very large molecules are transported? | [
"migration",
"passive transport",
"active transport",
"diffusion"
] | C | Active transport requires energy from the cell. It occurs when substances move from areas of lower to higher concentration or when very large molecules are transported. Types of active transport include ion pumps, such as the sodium-potassium pump, and vesicle transport, which includes endocytosis and exocytosis. |
SciQ | SciQ-3463 | thermodynamics, everyday-life, cooling, humidity
This is actually a very good question. There appears to be two competing factors involved. Evaporative cooling due to transpiration from the trees cools the air, increasing heat transfer away from the skin making it feel "cooler". But at the same time you would think transpiration increases the humidity in the air, potentially interfering with evaporative cooling of skin perspiration, making you feel "warmer"
The fact that you experienced "cool" rather than "warm" suggests to me that the relative humidity (RH) of the air was low at the time, so that it was capable of absorbing the moisture and cooling the air without significantly raising the RH under the tree to interfere with evaporation of skin perspiration, thus making you feel "cool".
If the RH was high, particularly at or near saturation (100%), transpiration evaporation from the tree, and its cooling effect, ceases. Likewise, evaporative cooling of perspiration ceases, both of which would make you feel "warm". For more information on transpiration of plant, see: https://www.polygongroup.com/en-US/blog/how-humidity-affects-the-growth-of-plants/
Bottom line: The higher the RH the warmer you will feel, whether you are under a tree or not.
Hope this helps.
The following is multiple choice question (with options) to answer.
What is the term for how the air feels at its temperature and humidity | [
"climate sensory index",
"relative humidity",
"atmospheric humidity",
"initial humidity"
] | B | Relative humidity is how the air feels at its temperature and humidity. |
SciQ | SciQ-3464 | organic-chemistry, biochemistry, carbohydrates
Title: Is formaldehyde a carbohydrate? Formaldehyde has the formula $\ce{CH2O}$, and the ratio of atoms in a simple carb is $\ce{1C:2H:1O}$. This fits the formula of carbohydrates. When I researched this, I found some sources saying that formaldehyde is the simplest carb, but other sources saying it is glycolaldehyde ($\ce{C2H4O2}$). Is formaldehyde a carbohydrate? According to IUPAC definition:
‘carbohydrate’ includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups to carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom, an amino group, a thiol group or similar heteroatomic groups. It also includes derivatives of these compounds [...]
But according to Wikibooks
the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons. Natural saccharides are generally built of simple carbohydrates called monosaccharides with general formula $\ce{(CH2O)_n}$ where $n$ is three or more [...]
Because formaldehyde and glycolaldehyde (not a true sugar) has one and two carbon respectively in its structures we can exclude both as a carbohydrate.
The following is multiple choice question (with options) to answer.
What form does formaldehyde take at room temperature? | [
"solid",
"liquids",
"gas",
"plasma"
] | C | Formaldehyde is a gas at room temperature. Acetaldehyde boils at 20°C; in an open vessel, it boils away in a warm room. Most other common aldehydes are liquids at room temperature. |
SciQ | SciQ-3465 | electrons, metal, electronic-configuration
Title: Can a metal be forced to form an anion theoretically? I know that metals have the capability to lose electrons and form cations, but is it also theoretically possible to supply an electron to a metal so that it forms an anion?
If so, has it ever been done?
I referred this question (Can two metals combine to form a compound?) but could not get a satisfactory solution from that. Absolutely! You will find these mostly in electride systems and off these, mostly in alkali metals.
Here is an example research paper:
"Superakali-Alkalide Interactions and Ion Pairing in Low-Polarity Solvents, J. Am. Chem. Soc., 2021, 143(10), 3934–3943 (https://pubs.acs.org/doi/10.1021/jacs.1c00115)
Remember, metals have a positive charged when ionized because it is energetically more favorable to lose electrons than to gain them, this being of course an oversimplified version of electron orbitals and shells. If you have a situation in which this is reverse or not possible, you will get a negative metal ion
The following is multiple choice question (with options) to answer.
Ions are formed when atoms gain or lose what? | [
"electrons",
"neutrons",
"protons",
"mass"
] | A | Electron Configurations of Ions We have seen that ions are formed when atoms gain or lose electrons. A cation (positively charged ion) forms when one or more electrons are removed from a parent atom. For main group elements, the electrons that were added last are the first electrons removed. For transition metals and inner transition metals, however, electrons in the s orbital are easier to remove than the d or f electrons, and so the highest ns electrons are lost, and then the (n – 1)d or (n – 2)f electrons are removed. An anion (negatively charged ion) forms when one or more electrons are added to a parent atom. The added electrons fill in the order predicted by the Aufbau principle. |
SciQ | SciQ-3466 | optics, quantum-electrodynamics
According to Schroedinger's model of the atom, only particular colors are emitted depending on the type of atom and the state of its electrons. Then, how it is possible that the same type of matter changes color in relation to temperature? For example, water is transparent with a light blue tint, but snow is white (which means, pretty much, that photons have no particular color in the visible spectrum).
Split by request: See the other part of this question here. It's important to distinguish different phases of the material. While it's true that water and snow consists of the same building blocks of $H_2 O$, those individual blocks are actually not as important as the resulting material. You can build a storage room and pyramids just out of bricks (at least in principle).
Gases
Let's start with the simplest case. Simplest in the sense that there is not much going on, just molecules flying around. Let us just assume ideal gas where molecules don't interact with each other. Then to explain everything it suffices to look at just one molecule.
The color of the molecule of course arises because of its absorption spectrum. This in turn depends on the molecule's energy levels. For atoms these are pretty nice discrete levels. For more complicated molecules you also have rotational and vibrational degrees of freedom to take into account and besides discrete levels you'll also see continuous strips that consist of very fine energy levels corresponding to that. For illustration, see the wikipedia article on $H_2$ hydrogen.
In any case, if you are somehow able to obtain that energy spectrum you can then investigate the macroscopic properties by the means of the usual Boltzmann statistics
$$\hat W = Z^{-1} \exp(-{\beta \hat H}) = Z^{-1} \sum_n\exp(- \beta E_n) {\hat P}_n $$
with $Z = {\rm Tr} \exp(-{\beta \hat H})$ being the partition function, $\beta$ the inverse temperature and $P_n$ projector on $n$-th energy level.
Using this you can see that as you increase temperature the energy level distribution will change to occupy higher levels and this in turn will change the probability of individual absorption processes between certain levels.
The following is multiple choice question (with options) to answer.
What are the three ways to classify matter based on how light interacts with it? | [
"opaque, invisible, visible",
"extensive , opaque , translucent",
"transparent, opaque, translucent",
"transitive, opaque, translucent"
] | C | Light may interact with matter in several ways, including reflection, refraction, transmission, and absorption. Matter can be classified on the basis of how light interacts with it as transparent, translucent, or opaque. |
SciQ | SciQ-3467 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
In what area of the body are sutural bones found? | [
"legs",
"tooth",
"skull",
"skin"
] | C | Sutural bones are small, flat, irregularly shaped bones. They may be found between the flat bones of the skull. They vary in number, shape, size, and position. |
SciQ | SciQ-3468 | 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.
The ability of matter to combine chemically with other substances is known as? | [
"permeability",
"reactivity",
"solubility",
"turbidity"
] | B | Reactivity is the ability of matter to combine chemically with other substances. Some kinds of matter are extremely reactive; others are extremely unreactive. For example, potassium is very reactive, even with water. When a pea-sized piece of potassium is added to a small amount of water, it reacts explosively. You can observe this reaction in the video at the URL below. ( Caution: Don’t try this at home!) In contrast, noble gases such as helium almost never react with any other substances. |
SciQ | SciQ-3469 | electromagnetism, frequency, radio-frequency, sensor, radar
Title: Why do sensors that emit higher frequency signals give more accurate data? I am doing a technical presentation about RADAR and LiDAR. I understand that LiDAR is several times more accurate and capable of producing really detailed 3-D maps of their surroundings, while RADARs tend to lag behind in accuracy.
Several sources indicate that the shorter wavelength signals from LiDAR contribute to its higher accuracy, but they don't really explain why.
This webpage explains that higher frequency signals yield more accurate data in RADARs, but does not really explain why either:
http://www.radartutorial.eu/07.waves/Waves%20and%20Frequency%20Ranges.en.html
There are some posts that mention the Heisenberg Uncertainty Principle, but I don't think an explanation at the atomic level is really relevant nor required to explain this phenomenon.
Can anybody give an equation or state a scientific concept as to why sensors/apparatuses that use higher frequency signals yield more accurate data? In the article that anna v mentioned:
robotsforroboticists.com/lidar-vs-radar
there is a segment which states:
"The down side [of the RADAR] is that if an object is much smaller than the RF wave being used, the object might not reflect back enough energy to be detected. For that reason many RADAR’s in use for obstacle detection will be “high frequency” so that the wavelength is shorter (hence why we often use mm-wave in robotics) and can detect smaller objects."
This does provide some intuitive understanding as to why devices emitting higher frequency signals provide high-resolution data. Small objects and the small/fine details of large objects (ie. protrusions of a wall, a pedestrian's facial features, and bumps/cracks/curves that make up the texture of any surface) do not reflect enough low-frequency EM wave energy back to the RADAR. Thus, such fine details are not detected by RADAR.
If the generated signals were of higher frequency, then the EM wave oscillates faster, and a greater percentage of the wave would hit and be reflected by small objects and the fine details of large objects (ie. protrusions/bumps/curves). Thus, a sensor emitting waves at a higher frequency can detect such details.
The following is multiple choice question (with options) to answer.
Which types of waves are used for cell phones and radar? | [
"thermal waves",
"sound waves",
"microwaves",
"light waves"
] | C | Microwaves are used for cell phones and radar. |
SciQ | SciQ-3470 | zoology, microbiology, pathology
Title: Prevention of disease spreading in animal kingdom It's my first question on here, so I'm not sure If my question fits the theme. Please refer me to the appropriate one, If I have made a mistake.
So a question that I wanted to ask has to do with whether or not animals potentially try to avoid spreading diseases. So I was thinking... In an event that a really deadly disease emerges in a population, it would be really dangerous for animals that live in social groups, of any size really, not to have any instinctual behaviours that try and prevent the disease to spread. Animals that live in big heads, like wildebeests would just probably leave the diseased individuals behind, apes and monkey could potentially cast out individuals from the group, etc. Ants have separate sections in their tunnels that serve as graveyards, I presume for this exact purpose.
A lot of parasitic organisms have adaptations that specifically target animals with social behaviour, so why wouldn't animals adapt against that?
Something that also came to my mind is that this could possibly evolve not as a social behaviour of a group, but sometimes that individuals in a group would do, for example self isolation. However, I do not find this likely, I possibly requires higher cognitive understanding of disease spread.
Am I way of base here? If not, could you please provide some interesting examples you are familiar with.
The following is multiple choice question (with options) to answer.
Ticks spread bacteria that causes what condition? | [
"Malaria",
"Dengue fever",
"Rabies",
"lyme disease"
] | D | Bacterial Disease Vectors. Ticks spread bacteria that cause Lyme disease. Deerflies spread bacteria that cause tularemia. |
SciQ | SciQ-3471 | organic-chemistry, spectroscopy, nmr-spectroscopy
EDIT: to not get marked as homework, because it isnt, I suggesting that it should be some sort of pyrrole or pyrrolidine structure type. Further I think that the CH3 group must be shielded from other protons and is either near or is sitting at a heteroatom.
Next I have narrowed down two structural possibilities: either we have a proton sitting at the nitrogen and the other sitting on a double bound, or we have diastereotropic protons.
My best candidate so far is the picture below (please let me know if it would be possible): Finding a structure with the correct formula that matches the chemical shifts reasonably well is not so difficult.
The multiplet integrals, normalized such that the area corresponding to one $\ce{H}$ is $\approx 33$ suggests the following number of $\ce{H}$ (moving upfield): 1,1,2,2,3.
The upfield singlet suggests an uncoupled terminal methyl group, so we begin with the simplest assumption, that we have a molecule with a linear alkane.
For a linear alkane, the 4 remaining $\ce{C}$ require 7 bonds in addition to $\ce{3 C-C}$, $\ce{1 C-N}$, and $\ce{1 C-O}$ single bonds. The $\ce{N}$ requires 2 additional bonds, the O 1. Since there are $\ce{6 H}$ remaining, either unsaturation or multiple bonds such as $\ce{C=N}$ or $\ce{C=O}$ bonds are required (we dismiss ring formation for the time being).
The high chemical shift and simple coupling pattern suggests the methyl group sits next to an electron withdrawing group without protons, carbonyl would fit.
The following is multiple choice question (with options) to answer.
Methyl groups are found within what? | [
"amino acids",
"DNA molecules",
"rna acids",
"peptide chains"
] | A | Methyl groups are found within amino acids. |
SciQ | SciQ-3472 | human-biology, molecular-biology, human-physiology, immune-system, history
Title: Which landmark paper first described the differentiation of T-cells? T-cells are distinguished from B cells in part by their locus of differentiation/maturation (thymus). This is textbook knowledge, but I was wondering which particular person or people were responsible for making this discovery. I'd appreciate any links to their original papers/works. Thanks a lot! This paper appears to be a history of the discovery of B/T differentiation and the role of the thymus. I believe that you should find a number of important references therein.
It describes specifically a series of publications in the 1950s and 1960s that may be relevant (section "Identification of T and B cells"), such as this one by Gowans.
The following is multiple choice question (with options) to answer.
The primary lymphoid organs are the bone marrow and what else? | [
"kidneys",
"thymus gland",
"thyroid",
"pinneal gland"
] | B | Primary Lymphoid Organs and Lymphocyte Development Understanding the differentiation and development of B and T cells is critical to the understanding of the adaptive immune response. It is through this process that the body (ideally) learns to destroy only pathogens and leaves the body’s own cells relatively intact. The primary lymphoid organs are the bone marrow and thymus gland. The lymphoid organs are where lymphocytes mature, proliferate, and are selected, which enables them to attack pathogens without harming the cells of the body. |
SciQ | SciQ-3473 | gravity, fluid-dynamics, specific-reference, fluid-statics, boundary-conditions
Title: Surface tension of N non-mixing fluids I am a mathematician, not a physicist, so please be gentle with me if I write something wrong.
Consider a bounded, regular container $\Omega$, which is filled with the fluids $F_1,...,F_N$ which do not mix (i.e. $\bigcup_{i=1}^N F_i=\Omega$ and $F_i\cap F_j=\emptyset, \forall i\neq j$). Between two adjacent fluids $F_i,F_j$ there is a surface tension $\sigma_{ij}$ (which is eventually zero if $F_i$ and $F_j$ are not adjacent). The problem I want to study is given $F_i$ with volume $V_i$ and density $\rho_i$ then what is the final state in which the fluids will arrive.
There are three factors I have in mind:
the interaction of $F_i$ and $F_j$ with $i\neq j$ by their surface tension;
the interaction between $F_i$ and the boundary $\partial \Omega$ of the container;
the action of gravity on each $F_i$.
I have two questions:
Is there a relation of the form $\sigma_{ij}+\sigma_{kl}=\sigma_{ik}+\sigma_{jl}$ (scalar or vectorial) between the surface tensions?
The following is multiple choice question (with options) to answer.
Surface tension and viscosity are generally associated with what form or state of matter? | [
"gases",
"electrons",
"liquids",
"solids"
] | C | Two interesting properties of liquids are surface tension and viscosity. |
SciQ | SciQ-3474 | hydrocarbons, hydrogen
Title: Why carbon monoxide reacts with hydrogen to give different products in the presence of different catalysts My books says how carbon monoxide will react with hydrogen to give different products with different catalysts, but how exactly do different catalysts yield different products. Do they provide different pathways for entirely different mechanisms, or is the formation of some products is better thermodynamically and for that reaction to occur some catalysts provide the necessary activation energy and the others cant. The thermodynamics are always the same. If you go from carbon monoxide to methane, there is only one final enthalpy, and if you have the choice of going to methane or methanol the thermodynamically preferred product is always the same.
The difference indeed less within the different pathways and the activation barriers needed to get from one intermediate to the next. This isn’t really thermodynamics, it is mainly kinetics (although you can argue about thermodynamically preferred intermediates). The pathways are often very complex and entire papers revolve around how one reaction is catalysed on such a solid state catalyst, so please forgive me for not looking them up; but the general point still stands: one catalyst will lead to intermediates where the $\ce{C-O}$ bond is easily broken (and thus give methane), the other will not (and thus give methanol).
The following is multiple choice question (with options) to answer.
What catalyst substances may also allow reactions to occur by different pathways that have lower activation energy? | [
"hormones",
"calories",
"enzymes",
"carbohydrates"
] | C | Enzymes may also allow reactions to occur by different pathways that have lower activation energy. |
SciQ | SciQ-3475 | genetics, gene-synthesis
The dominant/recessive concept is useful in cases where there is a limited number of possible allele pairs and one or several alleles can mask the effect of other alleles. This is a very limited set of cases. Many genes have many different alleles, and it's hard to account for all of them. Many alleles also do not have a clear observable effect, in which case any "masking" effect is not prominent. To quote Wikipedia (2):
The following is multiple choice question (with options) to answer.
Gap genes are defined by the effect of what in that gene? | [
"modification",
"infection",
"mutation",
"radiation"
] | C | One example of a gap gene is the Krüppel gene, which regulates the activity of a number of other genes. Krüppel literally means "cripple" in German, named for the crippled appearance of mutant larva. Gap genes are defined by the effect of a mutation in that gene, and Krüppel is one such effect. Other gap genes are known as tailless and knirps (a "squirt or whippersnapper"). Gap genes encode transcription factors which directly effect the expression of additional genes involved in embryo segmentation, called the pair-rule genes . Pair-rule genes are expressed in alternating segments within the developing embryo. Pair-rule genes have very creative names, such as even-skipped, hairy, odd-skipped, odd-paired, sloppy paired and fushi tarazu , which is Japanese for “few segments. ” See My favorite silly gene names at http://www. itsokaytobesmart. com/post/82318778810/funny-gene-names for a list of other interesting gene names. |
SciQ | SciQ-3476 | hematology, cardiology, blood-circulation, red-blood-cell, veins
Veins are not like impermeable rubber tubes, they are 'living' structures requiring, like all cells, Oxygen and glucose to survive. Smaller veins get the O2 from diffusion, while the larger veins need help from vasa vasorum, small blood bessels that bring blood to the walls of the veins.
The innermost cells lining veins are epithelial cells. They also line valves.
In the picture you posted, blood is not circulating well behind valves. The cause of hypoxia is that epithelial cells are continually removing O2 from the blood.
When enough O2 is removed to cause hypoxia, the endothelial cells may become damaged by the lack of O2, causing inflammation and (possibly) potentiating clot formation.
Activation of endothelial cells by hypoxia or possibly inflammatory stimuli would lead to surface expression of adhesion receptors that facilitate the binding of circulating leukocytes and microvesicles. Subsequent activation of the leukocytes induces expression of the potent procoagulant protein tissue factor that triggers thrombosis.
Mackman N. (2012). New insights into the mechanisms of venous thrombosis. The Journal of clinical investigation, 122(7), 2331–2336. doi:10.1172/JCI60229
The following is multiple choice question (with options) to answer.
The abnormal cells cannot carry oxygen properly and can get stuck where? | [
"capillaries",
"muscles",
"Arteries",
"Viens"
] | A | The red blood cells of a person with sickle-cell anemia (left) are long and pointed, rather than straight, like normal cells (right). The abnormal cells cannot carry oxygen properly and can get stuck in capillaries. |
SciQ | SciQ-3477 | symmetry, atoms
Title: Is hydrogen the same everywhere? Silly thought. Feel free to shoot it down
Does a hydrogen atom undergo any kind of change subject to it's environment?
If one were to study a hydrogen atom on the surface of Mercury, another above Earth, and a third in interstellar space - would they exhibit any difference/s? This is quite far from a silly thought although this is not apparent at first sight. Apart from a couple of details which are well understood and have firm physics behind them - such as the fact that deuterium and tritium exist in some proportion and the hyperfine-structure distinction between ortho- and parahydrogen, as far as we can tell all hydrogen atoms are exactly the same. This is in fact the case for all atoms and molecules: all iron atoms are exactly replaceable (so long as you take the right isotope) and nitrogen molecules are all the same (so long as you take them in the correct electronic, nuclear and spin states), and so on.
This is one of the most profound symmetries in nature and it holds irrespective of geographical / astronomical position, chemical history, temperature, and so on. How can we tell? Well, the very fact that we can do chemistry with atoms is why - the basic tenet is that the world is made of a finite set of "blocks" and that combinations of them make the interesting materials around us. The success of chemistry as a discipline means that there's something to that basic tenet.
How can we tell that atoms in places we haven't been are the same as here? Of course, our evidence for that is not as strong, but it's built on the fact that astrophysics works just using physics of different kinds we can see experimentally here on Earth. We can do spectral analysis of the solar corona, for example, and if we see energy levels slightly displaced then we can explain that as Doppler shifts or magnetic fields that let us explore a richer and (as far as we can tell) fully consistent physical picture. We can do chemistry on the atmospheres of other planets and, though it's rather hard, come up with consistent chemical explanations for all our observations. We can link the nuclear physics we observe in accelerators and reactors to explain our observations of our Sun and other stars and see that they match what we do here.
The following is multiple choice question (with options) to answer.
All atoms of the same element share the same number of what type of particle? | [
"nucleus",
"neutrons",
"protons",
"quarks"
] | C | Atoms have protons and neutrons in the center, making the nucleus, while the electrons orbit the nucleus. The modern atomic theory states that atoms of one element are the same, while atoms of different elements are different. What makes atoms of different elements different? The fundamental characteristic that all atoms of the same element share is the number of protons. All atoms of hydrogen have one and only one proton in the nucleus; all atoms of iron have 26 protons in the nucleus. This number of protons is so important to the identity of an atom that it is called the atomic number of the element. Thus, hydrogen has an atomic number of 1, while iron has an atomic number of 26. Each element has its own characteristic atomic number. Atoms of the same element can have different numbers of neutrons, however. Atoms of the same element (i. , atoms with the same number of protons) with different numbers of neutrons are called isotopes. Most naturally occurring elements exist as isotopes. For example, most hydrogen atoms have a single proton in their nucleus. However, a small number (about one in a million) of hydrogen atoms have a proton and a neutron in their nuclei. This particular isotope of hydrogen is called deuterium. A very rare form of hydrogen has one proton and two neutrons in the nucleus; this isotope of hydrogen is called tritium. The sum of the number of protons and neutrons in the nucleus is called the mass number of the isotope. Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-3478 | ocean, thermodynamics
Your friend is half right, and half wrong. Air has a bit over 1/4th the heat capacity compared to water and it's about 800 times less dense, so he's correct, but it's not that simple.
Sunlight - somewhat counter-intuitively, isn't great at warming oceans because the photons from sunlight are energetic enough to evaporate water molecules into gas molecules. Oceans have low albedo which means they absorb most of the energy from the sunlight, but much of that heat is lost in evaporation by visible light photons. While that has nothing to do with your question, it's worth pointing out that sunlight isn't as good at warming oceans as one might think. (If anyone has one of those solar mirror ovens, I'd be curious to see how well they work on pure water . . . just out of curiosity, evaporation loss vs rate of warming).
The back-radiation from the atmosphere is comparatively much less total solar energy, but oceans are good at absorbing and storing thermal back-radiation reflected back off the greenhouse gas rich atmosphere into the ocean. This is a tiny amount of the total heat Earth gets from sunlight, and the increase of this radiation due to greenhouse gas is a fraction of one percent of solar energy, but it adds up.
One way to explain this is that 85 degree air will warm 80 degree water. That's a thermodynamic law. It just takes a while and because the heat capacity and density of water is much greater, it takes about 4 liters of air to give 1 degree back to warm 1 cc of water 1 degree. But despite the inefficiency, warmer air still transfers heat into colder water. It takes many decades, perhaps centuries, for the oceans to catch up to the warming air, but air, however inefficiently, does warm the oceans.
The following is multiple choice question (with options) to answer.
How do oceans help control global warming? | [
"Cooling air",
"reflecting light",
"releasing oxygen",
"absorbing carbon dioxide"
] | D | Ocean water also absorbs gases from the atmosphere. The most important are oxygen and carbon dioxide. Oxygen is needed by living things in the oceans. Much of the carbon dioxide sinks to the bottom of the seas. Carbon dioxide is a major cause of global warming. By absorbing carbon dioxide, the oceans help control global warming. |
SciQ | SciQ-3479 | geophysics, climate-change, glaciology
Title: When will the Final Ice Age happen? As the Sun's luminosity slowly rises, the Earth's surface temperature will climb. Will Earth ever be too warm to have any more glacial periods? If so, when will that be?
Edit: The existing answer misunderstood the question. I'd like some boundary conditions, e.g. "when the sun's luminosity is 10% higher and the Earth becomes a 'moist greenhouse'" and "when the Sun turns Earth into a cinder". Those conditions would imply that the last Ice Age will happen 1-4 billion years from now. A better estimate would be awesome. Unless there's something I'm missing, with Stefan-Boltzmann and some reasonable assumptions (e.g. linear increase in luminosity) it should be possible to get a back-of-the-envelope calculation for this. In my opinion, there's 3 primary factors. There's a difference between ice ages and ice age periods. The Milankovich cycles appear to play a key role in the forming and receding of individual ice ages, but what it doesn't appear to do is trigger ice age periods.
The modern Quaternary ice age period began about 2.58 million years ago. Milankovich cycles likely began long before then, so it's unlikely that Milankovich cycles triggered the period, only that they play a role in the cycle within the period.
Same is likely true for solar maximums and minimums. They come and go, but they aren't likely the drivers of ice age periods.
Timeline of glaciation
the Quaternary, the Karoo and the Andean-Saharan ice ages all happened in the last 450 million years, and they were separated by long periods so the cause should be looked at more long term. Milankovich cycles operate on 26,000, 42,000 and 100,000 timelines, much to short to drive changes over millions of years.
OK - the 3 things.
Land and ocean placement,
Solar output (long term, not short term sunspot changes), and
CO2
Land and Ocean Placement
The following is multiple choice question (with options) to answer.
What occurs between long warm climate periods? | [
"mass extinction",
"drought",
"ice ages",
"hurricanes"
] | C | Earth’s climate has changed many times. Long warm periods were broken up by ice ages. Over the past 150 years, climate has warmed quickly. |
SciQ | SciQ-3480 | states-of-matter, matter
Title: What distinguishes the difference states of matter from solid to BEC and perhaps fermionic condensate? Is it something to do with the behavior of electrons? How many states are there either discovered or predicted? 無
'States of matter' is a question of taxonomy, not of reality, and moreover, it's a result of the conditions surrounding the matter, not its internal properties. Certain combinations of properties give us a hint towards calling something 'solid' or 'liquid', but in truth there are no lines, just a continuous spectrum, and under certain conditions, matter transitions seamlessly through all sorts of states, both mundane and exotic:
Behold: Jupiter
A perfect example of this is Jupiter. Composed primarily of hydrogen, this gas giant consists (conjecturally) of a core of high-temperature hydrogen ice, floating in liquid hydrogen, enveloped in hydrogen gas, moving through interplanetary medium composed of hydrogen plasma.
Except not really: Under these conditions, the classical notions of states of matter break down entirely: Between these states of matter there are no interfaces, just a gradual, continuous transition.
In other words: The distinctive line to separate one state from another you are after doesn't really exist.
The following is multiple choice question (with options) to answer.
Which state of matter is characterized by molecules with minimal movement and strong forces between them? | [
"solid",
"gas",
"plasma",
"liquid"
] | A | Three main types of particles that make up all atoms are protons, neutrons, and electrons. |
SciQ | SciQ-3481 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
The plasma membrane pulls away from the cell wall as it shrivels. what is this process called? | [
"sporozoans",
"osmosis",
"fluctuations",
"plasmolysis"
] | D | A cell that does not have a rigid cell wall (such as a red blood cell), will swell and lyse (burst) when placed in a hypotonic solution. Cells with a cell wall will swell when placed in a hypotonic solution, but once the cell is turgid (firm), the tough cell wall prevents any more water from entering the cell. When placed in a hypertonic solution, a cell without a cell wall will lose water to the environment, shrivel, and probably die. In a hypertonic solution, a cell with a cell wall will lose water too. The plasma membrane pulls away from the cell wall as it shrivels, a process called plasmolysis. Animal cells tend to do best in an isotonic environment, plant cells tend to do best in a hypotonic environment. This is demonstrated in Figure below . |
SciQ | SciQ-3482 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
What collects fluid from a system of canals in the cytoplasm? | [
"chlorophyll",
"vacuole",
"mitochondria",
"placenta"
] | B | |
SciQ | SciQ-3483 | rain, natural-disasters, flooding
Edit 2 August 2020
Concerning successful flood control measures, two quickly come to mind, the Thames Barrier in London, England and the Aswan Dam in Egypt, particularly the Aswan High Dam.
The Thames Barrier is a movable barrier system that is designed to prevent the floodplain of most of Greater London from being flooded by exceptionally high tides and storm surges moving up from the North Sea. It has been operational since 1982. When needed, it is closed (raised) during high tide; at low tide, it can be opened to restore the river's flow towards the sea.
Based on the success of the Low Dam, then at its maximum utilization, construction of the High Dam became a key objective of the government following the Egyptian Revolution of 1952; with its ability to better control flooding, provide increased water storage for irrigation and generate hydroelectricity the dam was seen as pivotal to Egypt's planned industrialization. Like the earlier implementation, the High Dam has had a significant effect on the economy and culture of Egypt.
The following is multiple choice question (with options) to answer.
What is the name of artificial barriers that people build to protect shorelines? | [
"domes",
"breakwaters",
"outcroppings",
"seawalls"
] | B | Only a tiny fraction of the ocean floor has ever been studied. Why? Humans can’t travel deep below the water’s surface without special vehicles. The pressure of the water is too great. Total darkness and extreme cold make it even more difficult. That’s why people have worked for decades to invent technology for studying the ocean floor. |
SciQ | SciQ-3484 | valence-bond-theory
Title: How can anions exist? Consider an nitrogen atom with 7 protons and 7 electrons. How can an nitrogen anion $\ce{N^-}$ exist? Shouldn't the 7 electrons in valence shell repel the extra one?
What force does hold the extra one electron in the valence shell? There isn't an extra proton in the $\ce{N^-}$ that would hold the extra electron. One reason cations and anions exist is due to the stability of a full or half-full valence shell. The stability from those electronic configurations means that the atom or molecule does not require protons to "hold" the extra electron.
Recall also that nitrogen has three (or five) valence electrons, rather than seven. The 1s shell is full and is not considered part of its valency. The three 2p electrons are the valence electrons although they hybridize with the 2s electrons to produce the trigonal pyramidal structure of ammonia with its lone pair.
The single anion $\ce{N^-}$ could exist, but would not be stable because it puts four electrons in the p shell. The p shell would prefer to have three electrons as it does in the nitrogen atom or no electrons as it does in the $\ce{N^3+}$ cation.
The following is multiple choice question (with options) to answer.
How many valence electrons does nitrogen have? | [
"4",
"5",
"10",
"3"
] | B | Nitrogen is a diatomic element with five valence electrons. Create a model of a molecule of nitrogen. |
SciQ | SciQ-3485 | particle-physics, electrons, protons
Title: Is there a term for electron capture outside the nucleus? My textbook says that electron capture is when an electron is 'captured' by a proton in the nucleus which causes them to turn into a neutron and an electron neutrino. The name kind of suggests it only works in the nucleus though.
Is there a term for electron capture happening between just a lone proton and electron? The energetic requirements of $$e^- + p \longrightarrow n + \nu_e$$ are such that the electron needs around $1.4\,\mathrm{MeV}$ kinetic energy relative the proton for the reaction to proceed in free space (because of the difference in mass between the proton and the neutron). And even then this is a weak-mediated interaction, and so have a very small cross-section.
There are relatively few places where these conditions obtain (none that are friendly to unprotected humans). Where they do (mostly in the heart of stars) the reaction will be in equilibrium with the reverse reaction (beta decay of the neutron) with proton-neutron fusion removing nucleons from the equilibrium, and because of the small cross-section and the fleeting nature of moments when the preconditions are met the actual rate is trivial even compared to the very slow process of proton-proton fusion (if this event were common in the sun we'd see it in solar neutrino experiments, but we don't).
The following is multiple choice question (with options) to answer.
What is the term for a particle from outside the cell engulfing the cells membrane? | [
"metastasis",
"mitosis",
"endometriosis",
"endocytosis"
] | D | In endocytosis, a substance or particle from outside the cell is engulfed by the cell membrane. The membrane folds over the substance and it becomes completely enclosed by the membrane. There are two main kinds of endocytosis: pinocytosis and phagocytosis. |
SciQ | SciQ-3486 | blood-circulation, kidney
Title: Why does glomerulus don't allow white blood cells to leave? The glomerulus in nephrons are just a ball of capillaries, so why can't it allow the white blood cells to squeeze though the epithelial cells into Bowman's capsule just like the formation of tissue fluid in other capillaries by filtration? Red blood cells, White blood cells, platelets and proteins with large molecular weight cannot pass through the podocyte and fenestrations in glomerular capillary, but small molecules like water, salts and sugars are filtered out as part of urine.
As these cells and proteins are large to cross through this filter, they remain in the capillary and create osmotic pressure within the capillary. Bowman’s space has osmotic pressure approximately zero. So, only hydrostatic pressure works in this state and help in movement of fluid across the capillary wall.
Via: https://opentextbc.ca/anatomyandphysiology/chapter/25-5-physiology-of-urine-formation/
The following is multiple choice question (with options) to answer.
The kidney glomerulus filters blood mainly based on particle size to produce a filtrate lacking cells or large what? | [
"proteins",
"steroids",
"carbohydrates",
"lipids"
] | A | CHAPTER REVIEW 25.1 Physical Characteristics of Urine The kidney glomerulus filters blood mainly based on particle size to produce a filtrate lacking cells or large proteins. Most of the ions and molecules in the filtrate are needed by the body and must be reabsorbed farther down the nephron tubules, resulting in the formation of urine. Urine characteristics change depending on water intake, exercise, environmental temperature, and nutrient intake. Urinalysis analyzes characteristics of the urine and is used to diagnose diseases. A minimum of 400 to 500 mL urine must be produced daily to rid the body of wastes. Excessive quantities of urine may indicate diabetes insipidus or diabetes mellitus. The pH range of urine is 4.5 to 8.0, and is affected by diet. Osmolarity ranges from 50 to 1200 milliosmoles, and is a reflection of the amount of water being recovered or lost by renal nephrons. |
SciQ | SciQ-3487 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What is the general composition of the continental crust? | [
"granite",
"sandstone",
"limestone",
"marble"
] | A | The average composition of continental crust is granite. |
SciQ | SciQ-3488 | climate-change, climate
In this case, as it is an area that it is almost constantly cloudy with high humidity, temperature is varying just a little bit, and except the first day of the period, it seems that there is no relationship. In fact, on the second day there was a storm (I am living now at Singapore) and it is reflected in a quick change in temperature (both) and solar radiation.
Conclusion: It is not as simple as it seems.
Hope it helps!
The following is multiple choice question (with options) to answer.
What term refers to the conditions of the atmosphere from day to day? | [
"climate",
"weather",
"humidity",
"temperture"
] | B | Climate is the average weather in an area over a long period of time. Weather refers to the conditions of the atmosphere from day to day. Climate is generally described in terms of temperature and moisture. |
SciQ | SciQ-3489 | electromagnetic-radiation, visible-light, thermal-radiation, absorption, photon-emission
For example, hydrogen gas emits light primarily at a wavelength of 656 nm (in the red region of the spectrum) when it makes transitions from the n=3 energy level to the n=2 energy level. However, at a high enough temperature, hydrogen atoms may be excited to higher energy levels and will emit light at a different set of wavelengths. Similarly, each element and molecule may have their own unique set of emission spectra based on its energy level transitions.
The following is multiple choice question (with options) to answer.
Gases such as neon, argon, and krypton produce what using electroluminescence? | [
"light",
"colors",
"heat",
"electricity"
] | A | Another type of luminescence is called electroluminescence. In this process, a substance gives off light when an electric current passes through it. Gases such as neon, argon, and krypton produce light by this means. The car dash lights in the Figure below are produced by electroluminescence. |
SciQ | SciQ-3490 | cardiology, embryology, pain, central-nervous-system
Title: At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'? According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed.
But according to this article, the heart starts beating at day 16.
And according to this article, the nervous system controls the rate beating of the heart.
Then my question is, **how can it be assured that the nervous system isn't developed until 19 weeks, when the nervous system controls the heart beating rate since day 16? First, there is some confusion on your part about heart cells and pain perception. Heart cells generate an action potential intrinsically; they do not need the central nervous system to beat (your second article explains this; read the part about the importance of calcium.) So yes, long before a fetus can feel pain, the heart is beating, because there must be circulation of nutrients throughout the embryo.
Secondly, the vagus nerve and sympathetic nerves can affect heart rate (the former by slowing it down when firing). These nerves start to reach their endpoints late in week 4 of development. So 19 days is not correct.
Cardiac sympathetic system
Although the primitive human heart starts to beat at 21 to 22 d, heart development continues to day 50, and it is near the end of this period, during the fifth week, that thoracic neural crest cells migrate from the neural tube through the somites and form aggregations (ganglia) near the dorsal aorta. [emphasis mine]
To experience pain, however, requires maturation of certain parts of the brain, most importantly, part of the thalamus and the cerebral cortex:
Current theories of pain consider an intact cortical system to be both necessary and sufficient for pain experience. In support are functional imaging studies showing that activation within a network of cortical regions correlate with reported pain experience. Furthermore, cortical activation can generate the experience of pain even in the absence of actual noxious stimulation. These observations suggest thalamic projections into the cortical plate are the minimal necessary anatomy for pain experience. These projections are complete at 23 weeks' gestation. [emphasis mine]
The following is multiple choice question (with options) to answer.
By how many weeks do all major organs start developing? | [
"9",
"8",
"12",
"4"
] | B | |
SciQ | SciQ-3491 | surface-tension
Title: What is the surface tension of liquids in space? I mean does surface tension exists in space on liquids?
Let's take an example if I have to write something using ballpen in space and space does not have gravity. Does it works because of the surface tension? Surface tension does exist "in space", which I take you to mean "without gravity". Surface tension in liquids is simply the attractive interactions between the molecules of a liquid. That exists whether there is gravity or not. I think most pens will not work well without being in the proper orientation in gravity, though. If you try using a normal ballpoint pen and write on a paper on the ceiling, you'll probably find that it won't work because gravity is pushing the ink in the wrong direction.
The following is multiple choice question (with options) to answer.
Surface tension is a property that can be found in what state of matter? | [
"vapor",
"liquid",
"water",
"ice"
] | B | 12.2 Bernoulli’s Equation 4. You can squirt water a considerably greater distance by placing your thumb over the end of a garden hose and then releasing, than by leaving it completely uncovered. Explain how this works. Water is shot nearly vertically upward in a decorative fountain and the stream is observed to broaden as it rises. Conversely, a stream of water falling straight down from a faucet narrows. Explain why, and discuss whether surface tension enhances or reduces the effect in each case. Look back to Figure 12.4. Answer the following two questions. Why is. |
SciQ | SciQ-3492 | plant-physiology
Title: Would a plant survive if it was watered using hard-water? Hard water is water with high mineral/salt content. I'm told that a potted plant watered with a salt solution dries out sooner or later. Is this true?
If so, would a plant survive if watered using hard-water? It would depend on the content of the hard-water. If the water contained heavier metals like lead or radioactive elements like tritium (Hydrogen-3), the plant would most likely die. Most land plants cannot survive when watered with massive amounts of salt water as the salt would absorb the water from the leaves.
The following is multiple choice question (with options) to answer.
A plant that forms special tissues for storing water in an arid climate is an example of the plant evolving what? | [
"adaptations",
"consciousness",
"divergence",
"additions"
] | A | Organisms evolve adaptations that help them survive in the climate of the biome where they live. For example, in biomes with arid climates, plants may have special tissues for storing water (see Figure below ). The desert animals pictured in Figure below also have adaptations for a dry climate. |
SciQ | SciQ-3493 | physiology, senescence, organs
Kidney: 7.2 years
Liver: 16.9 years
Lung: 2.1 years
Heart: 14.5 years
Kidney-Pancreas: 12.9 years
These numbers are not definite, since the life style of the donor and the receiver as well as infections of the transplated patient (who has a severely suppressed immune system – this is critical) also play an important role in determining the lifetime of the organ.
The following is multiple choice question (with options) to answer.
What organ is made up of over one million nephrons that dot the renal cortex? | [
"stomach",
"lungs",
"gall bladder",
"kidney"
] | D | Which of the following statements about the kidney is false? a. The renal pelvis drains into the ureter. The renal pyramids are in the medulla. The cortex covers the capsule. Nephrons are in the renal cortex. Because the kidney filters blood, its network of blood vessels is an important component of its structure and function. The arteries, veins, and nerves that supply the kidney enter and exit at the renal hilum. Renal blood supply starts with the branching of the aorta into the renal arteries (which are each named based on the region of the kidney they pass through) and ends with the exiting of the renal veins to join the inferior vena cava. The renal arteries split into several segmental arteries upon entering the kidneys. Each segmental artery splits further into several interlobar arteries and enters the renal columns, which supply the renal lobes. The interlobar arteries split at the junction of the renal cortex and medulla to form the arcuate arteries. The arcuate “bow shaped” arteries form arcs along the base of the medullary pyramids. Cortical radiate arteries, as the name suggests, radiate out from the arcuate arteries. The cortical radiate arteries branch into numerous afferent arterioles, and then enter the capillaries supplying the nephrons. Veins trace the path of the arteries and have similar names, except there are no segmental veins. As mentioned previously, the functional unit of the kidney is the nephron, illustrated in Figure 41.6. Each kidney is made up of over one million nephrons that dot the renal cortex, giving it a granular appearance when sectioned sagittally. There are two types of nephrons— cortical nephrons (85 percent), which are deep in the renal cortex, and juxtamedullary nephrons (15 percent), which lie in the renal cortex close to the renal medulla. A nephron consists of three parts—a renal corpuscle, a renal tubule, and the associated capillary network, which originates from the cortical radiate arteries. |
SciQ | SciQ-3494 | energy, energy-conservation, biophysics
Title: How efficient is the human body? This question sort of comes to mind when hearing how efficient an internal combustion engine is turning chemical energy in mechanical energy (something like 20-40%) with lots of excess heat. As an analog, how efficient is (or potentially) the human body at turning food into energy? Please bare with me, I realise there LOTS of different variables (how much the person weighs vs mass, metabolism, diet, etc). But I would imagine that there shouldn't be much margin of error given that most people maintain the same constant temperature (98 F +/- 1 degree). The MET (Metabolic Equivalent Task) readout on your gym equipment is your body doing 1Kcal/kg/h = 4184 J/kg/h and can be reasonably accurately measured by how much oxygen a test victim uses.
Sitting still is roughly 1 met and cycling at 100 Watts is around 5.5 Mets.
So taking a man of 75kg, cycling at 100Watts (100J/s) he is having to do 5.5 * 4184 * 75 / 3600s = 480Watts so an efficency of 20%
Remember though that the person is spending 80-100Watts just staying alive doing nothing - unlike your car. There is an interesting experimental fit to how much energy you need to just stay alive, calculated about 100 years ago, the Harris-Benedict equation
The following is multiple choice question (with options) to answer.
Human metabolism is the conversion of food into heat transfer, work, and this? | [
"stored protein",
"stored carbs",
"stored fat",
"stored atp"
] | C | Human Metabolism and the First Law of Thermodynamics Human metabolism is the conversion of food into heat transfer, work, and stored fat. Metabolism is an interesting example of the first law of thermodynamics in action. We now take another look at these topics via the first law of thermodynamics. Considering the body as the system of interest, we can use the first law to examine heat transfer, doing work, and internal energy in activities ranging from sleep to heavy exercise. What are some of the major characteristics of heat transfer, doing work, and energy in the body? For one, body temperature is normally kept constant by heat transfer to the surroundings. This means Q is negative. Another fact is that the body usually does work on the outside world. This means then, the body loses internal energy, since. |
SciQ | SciQ-3495 | 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.
What organ do mammals have that is exceptionally large for their body size? | [
"heart",
"liver",
"lungs",
"brain"
] | D | Cerebral Cortex Compared to other vertebrates, mammals have exceptionally large brains for their body size. An entire alligator’s brain, for example, would fill about one and a half teaspoons. This increase in brain to body size ratio is especially pronounced in apes, whales, and dolphins. While this increase in overall brain size doubtlessly played a role in the evolution of complex behaviors unique to mammals, it does not tell the whole story. Scientists have found a relationship between the relatively high surface area of the cortex and the intelligence and complex social behaviors exhibited by some mammals. This increased surface area is due, in part, to increased folding of the cortical sheet (more sulci and gyri). For example, a rat cortex is very smooth with very few sulci and gyri. Cat and sheep cortices have more sulci and gyri. Chimps, humans, and dolphins have even more. |
SciQ | SciQ-3496 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
Mammals have four limbs and produce what kind of eggs? | [
"hard-shelled",
"placental",
"umbilical",
"amniotic"
] | D | Mammals have four limbs and produce amniotic eggs. |
SciQ | SciQ-3497 | physiology, nutrition, organic-chemistry
Title: How is it known that there are only three macronutrients: proteins carbohydrates and lipids? It is stated here that in human nutrition, micronutrients are nutrients required generally in less than 100 mg daily quantities whereas macronutrients are required in gram quantities. It is widely stated that our macronutrients are carbohydrates, lipids, and proteins. How was it shown that these are the human macronutrients and that we don't have other macronutrients?
One answer to this similar question on Quora suggests that ethanol or ketones could be considered macronutrients. Ethanol is mentioned in this article, though ketones are not. Other sources I saw didn't clarify. Summary
The question is based on the misconception that the term “macronutrient” originated as a scientific definition, to which entities satisfying this definition were assigned. In fact it was a default term used as a distinction from compounds falling into the earlier category, “micronutrient”, and was used initially to encompass the three specific classes of food that had been established to be sources of energy through decades of nutritional research. Hence there was no question of whether there “should” be more macronutrients. The term is not a scientific definition, and today is used in different ways so that anyone using the term needs to clarify what it should be taken to mean in that particular context.
Food Energy and the history of Nutrition
Scientific studies of nutrition, dating the late 18th century, were initially concerned with chemical structure, metabolic fate and energy produced by different foods, and this is described in a short readable article by Ned Stafford in Nature (2010) 468, S16–17.
By the end of the 19th century protein, fat and carbohydrate had been established as the chemical fuels that supplied energy from the diet, and the energy values (in terms of the, now obsolete, calorie) had been established by Atwood, using his respiration calorimeter.
Micronutrients
The following is multiple choice question (with options) to answer.
Name the missing call of biochemical compound: carbohydrates, proteins, nucleic acids. | [
"microorganisms",
"enzymes",
"lipids",
"tissues"
] | C | Lipids are one of four classes of biochemical compounds, which are compounds that make up living things and carry out life processes. (The other three classes of biochemical compounds are carbohydrates, proteins, and nucleic acids. ) Living things use lipids to store energy. Lipids are also the major components of cell membranes in living things. Types of lipids include fats and oils. |
SciQ | SciQ-3498 | bond, electrons, lewis-structure, valence-bond-theory
Let's next examine the situation in $\ce{O2}$. Here is the molecular orbital diagram for $\ce{O2}$. As we again fill the orbitals with electrons according to the Aufbau Principle we again arrive at the point where we have two electrons remaining and the next available molecular orbital is the $\ce{\pi^{x}_{g}}$. But we see that there is a second orbital at exactly the same energy (degenerate) and it is the $\ce{\pi^{y}_{g}}$ orbital. According to Hund's Rule, rather than put both electrons into one of these orbitals, we place just one electron in each of these two degenerate orbitals. So while
$\ce{O2}$ does have two non-bonding electrons, they are not paired up - there is no lone pair, these electrons exist in separate orbitals and $\ce{O2}$ consequently has a triplet ground state resulting from these two unpaired non-bonding electrons.
So sometimes a non-bonding pair of electrons will exist as a lone pair (as in the case of water), sometimes they won't exist as a lone pair as in the case of oxygen. To solve these kinds of problems one must know (or guess) the structure of the molecule and then determine the molecular orbital arrangement. Then, when we fill these orbitals with electrons we will see if any non-bonding electrons will exist as a lone pair in a single orbital, or if the two non-bonding electrons will exist in separate orbitals and remain unpaired.
The following is multiple choice question (with options) to answer.
The ether functional group consists of an oxygen atom which forms single bonds with what other atoms? | [
"carbon",
"enzymes",
"hydrogen",
"acid"
] | A | The ether functional group consists of an oxygen atom which forms single bonds with two carbon atoms. |
SciQ | SciQ-3499 | thermodynamics, temperature, boiling-point
Title: How it was decided that the freezing point of water in the Kelvin scale of temperature should be 273.15 K? While discussing about the different temperature scales, our teacher told us about the freezing point and boiling point of water in different scales. I asked my teacher that how these numbers were decided, like why it was decided that 273.15 should be the freezing point of water in Kelvin scale and not some other number, but could not get a satisfactory answer. So, here I am requesting if anyone could tell me the reasons for giving the different specific numbers in different scales for the same temperature, in the simplest way possible. History: the Celsius scale was defined first; the zero on the Kelvin scale is dependent on that definition
It may seem awkward and annoying that the zero point on the Kelvin scale (and therefore the freezing point of water) isn't an exact number, but it is a consequence of history.
There used to be a variety of different temperature scale in the early history of chemistry. The Fahrenheit scale annoyingly used by a small number of countries to confuse science students, is one legacy of that era. And this matters because of how the scales were defined.
The original definition of the celsius scale was based on the freezing point and boiling point of pure water under very carefully defined conditions. The difference between the two temperatures was divided into 100 for convenience (it is certainly more convenient than the Fahrenheit scale which divides that interval into 180 parts though the original definition of the endpoints was more complicated and convoluted). The Kelvin scale came later but uses exactly the same interval as the celsius scale. The bp was set at 100 celsius and the freezing point at 0 celsius.
But this definition occured long before we knew there was an absolute lower limit for temperature. And it was based on empirical observations. When chemists and physicists got to grips with thermodynamics and started to explore really low temperatures, it was too late to define a new scale with different definitions. So when experiments revealed that there was a lower limit, absolute zero, they could only measure what that number was on the celsius scale as it made little sense to devise a new scale and mess with all the existing definitions.
The following is multiple choice question (with options) to answer.
In celsius, what is the boiling point of water? | [
"ninety eight degrees",
"zero degrees",
"two hundred twelve degrees",
"one hundred degrees"
] | D | The crystal structure of ionic compounds is strong and rigid. It takes a lot of energy to break all those ionic bonds. As a result, ionic compounds are solids with high melting and boiling points. You can see the melting and boiling points of several different ionic compounds in the Table below . To appreciate how high they are, consider that the melting and boiling points of water, which is not an ionic compound, are 0°C and 100°C, respectively. |
SciQ | SciQ-3500 | reproduction, asexual-reproduction
Title: can self-fertilization in flowers be called asexual reproduction? Suppose a flower having both male and female reproductive parts is self-fertilized then can this be called asexual reproduction...?I'm quite confused cause in this case the fusion of male and female gametes do take place but again the gametes are from the same parent....please help. According to this article from Berkeley, asexual reproduction is:
Any reproductive process that does not involve meiosis or syngamy
Using this definition of asexual reproduction and knowing self-fertilization involves meiosis and syngamy, it is not asexual.
The following is multiple choice question (with options) to answer.
What is the process where sperm from the pollen of one flower fertilizes the egg of another flower? | [
"cross-pollination",
"static pollination",
"inter-pollination",
"mitosis"
] | A | In cross-pollination , sperm from the pollen of one flower fertilizes the egg of another flower. Like other types of sexual reproduction, cross-pollination allows new combinations of traits. Cross-pollination occurs when pollen is carried by the wind to another flower. It can also occur when animal pollinators, like honeybees or butterflies ( Figure below ), carry the pollen from flower to flower. |
SciQ | SciQ-3501 | organic-chemistry, molecular-structure, molecules
Title: Complex organic molecules I am studying astronomy and came across the following term in the astrochemistry course called 'complex organic molecules' or also written as COMs. My question is: What is exactly meant with these molecules? Is it just a molecule with more than one carbon atom? tl;dr: two different definitions. Astronomy: multiple carbon atoms in molecule. Chemistry: polymer
Interestingly enough, after reading about COMs here, as well as reading the Wikipedia page and the corresponding arXiv paper, it seems like chemists and astronomers have different definitions of what a complex organic molecule should be!
As far as I knew, in chemistry complex organic molecules were long polymers, such as proteins, which were composed of thousands upon thousands of amino acid units. In the astronomy paper, however, they cite other types of molecules.
$\ce{CH3OH,
CH3CHO, HCOOCH3 and CH3OCH3}$, all cited as "complex" (haha) organic molecules in the paper, would appear to chemists as relatively simple molecules. (I read the paper, because it piqued my interest that something like a protein could be found in space). I then read the Springer article.
The term “complex organic molecules” is used differently in astronomy and chemistry. In astronomy, complex organic molecules are molecules with multiple carbon atoms such as benzene and acetic acid. These molecules have been detected in interstellar space with radio telescopes. In chemistry, “complex organic molecules” refer to polymer-like molecules such as proteins.
The following is multiple choice question (with options) to answer.
What is an organic compound made up of small molecules called amino acids called? | [
"a fat",
"a carbohydrate",
"a compound",
"a protein"
] | D | A protein is an organic compound made up of small molecules called amino acids . There are 20 different amino acids commonly found in the proteins of living things. Small proteins may contain just a few hundred amino acids, whereas large proteins may contain thousands of amino acids. |
SciQ | SciQ-3502 | physical-chemistry, solubility, solutions
My confusion: Is $K_f$ solute dependent? If no, then why not?
I have this confusion because I'm used to solving problems in which if the solute is changed, then most of the constants related to various properties of the solution also changes. Some solutes form nearly ideal solutions up to moderate molalities, examples being glucose and sucrose in water. Such solutions allow fitting of freezing point temperature data to the following equation:
$$\mathrm{log}(1-x_s)=\frac{\Delta_{fus} H_m}{R}\left(\frac{1}{T_{m}}-\frac{1}{T}\right)$$
Taking various approximations which includes assuming that the heat of fusion is constant from $T$ to $T_m$ (the melting point of the pure solvent), that $x_s<<1$, and that $T_m\approx T$ you obtain the expression for the freezing point depression, $\Delta T = T_m - T$, in terms of the cryoscopic constant $K_f$ and solute molality $m_s$:
$$\Delta T = K_f m_s$$
where
$$K_f = \frac{M_wRT_m^2}{\Delta_{fus}H_m}$$
Since $K_f$ contains parameters that depend only on the solvent (not on the particular solute) the equation can (to within the limitations imposed by the above approximations) be applied to any solutes with which the solvent forms ideal solutions. Which is why you can determine $K_f$ with one solute only to use that same constant to later determine the concentration of another solute.
The following is multiple choice question (with options) to answer.
A solute generally does what to the freezing point of a solvent? | [
"raises it",
"regulates it",
"lowers it",
"increases it"
] | C | A solute generally lowers the freezing point of a solvent, which is called freezing point depression. For example, spreading salt on an icy road melts the ice. |
SciQ | SciQ-3503 | particle-physics, standard-model, quarks, beyond-the-standard-model
Title: Indivisiblity of quarks I have been researching the Standard Model of Particle Physics recently. According to the model, quarks are indivisible. Does this mean that quarks cannot be divided, or does it mean that if we were to divide them, we would be left with nothing? The former, although maybe we're wrong. It wouldn't be the first time.
The following is multiple choice question (with options) to answer.
The quarks in a particle are confined, meaning individual quarks cannot be what? | [
"directly observed",
"hypothesized",
"changed",
"separated"
] | A | Identify evidence for electroweak unification. The quarks in a particle are confined, meaning individual quarks cannot be directly observed. Are gluons confined as well? Explain. |
SciQ | SciQ-3504 | 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.
The monosaccharide glucose is broken down through a series of enzyme-catalyzed reactions known as what? | [
"photosynthesis",
"Digestion",
"Respiration",
"glycolysis"
] | D | The monosaccharide glucose is broken down through a series of enzyme-catalyzed reactions known as glycolysis. |
SciQ | SciQ-3505 | inorganic-chemistry
Title: Wood burning and carbon dioxide or monoxide? I am building greenhouse and i want to operate greenhouse at winter time. For heating i ll use wood. And also i am thinking to give back carbon monoxide which ll come from burning process of wood. There is a question, how can avoid to get carbon monoxide from burning wood, do i must give more air flow (or oxygen flow) to burning process? Or when you burn wood there is just one gas output that is carbon dioxide? A good reference to read is Laboratory and field investigations of particulate and carbon monoxide emissions from traditional and improved cookstoves Atmospheric Environment February 2009, Pages 1170–1181.
Unforntunately, there is a significant amount of carbon monoxide, from 29 to 118 grams of CO per kg of wood.
They find that the drier the wood, the less CO, but don't expect to completely eliminate CO.
The following is multiple choice question (with options) to answer.
What is the primary gas produced from burning of wood? | [
"Hydrogen Dioxide",
"carbon dioxide",
"toxic dioxide",
"liquid dioxide"
] | B | When wood burns, it changes to ashes, carbon dioxide, water vapor, and other gases. You can see ashes in the wood fire pictured here. The gases are invisible. |
SciQ | SciQ-3506 | physical-chemistry, thermodynamics
Relevant formulas:
\begin{align}
\Delta G_{\text{electrostatic gradient}} &= ZF\Delta \Psi\\
\Delta G_{\text{chemical gradient}} &= RT\ln\frac{C_\mathrm{in}}{C_\mathrm{out}}\\
\Delta G_{\text{hydrolysis of ATP}} &= -45000~\mathrm{J/mol}\\
\end{align}
Moving two positive $\ce{Ca^2+}$ ions against both a concentration gradient and an electrostatic gradient implies that $G_{\text{chemical gradient}}$ and $\Delta G_{\text{electrostatic gradient}} > 1$. The negative value for $\Delta G_{\text{hydrolysis of ATP}}$ means that hydrolysis of ATP is a spontaneous process, or a "work-yielding" process. The energy released from hydrolysing ATP is essentially what drives the transport process. Since we are transporting "4 charges" per ATP molecule, $\Delta G_{\text{chemical gradient}}$ is multiplied by 2. Also (I presume) the concentration of $\ce{Ca^2+}$ ions is larger on the inside of the cell than on the outside, implying that the concentration ratio is larger than 1.
The combined expression for $\Delta G$ for the unassisted transport is
$$\Delta G = RT\ln\frac{C_\mathrm{in}}{C_\mathrm{out}} + 2ZF\Delta \Psi$$
Rearranging this yields
$$\frac{C_\mathrm{in}}{C_\mathrm{out}} = \exp\left\{\frac{\Delta G - 2ZF\Delta\Psi}{RT}\right\}$$
The following is multiple choice question (with options) to answer.
What type of transport requires no energy and occurs when substances move from areas of higher to lower concentration? | [
"passive transport",
"active transport",
"immune transport",
"bacterial transport"
] | A | Passive transport requires no energy. It occurs when substances move from areas of higher to lower concentration. Types of passive transport include simple diffusion, osmosis, and facilitated diffusion. |
SciQ | SciQ-3507 | quantum-mechanics, atomic-physics
Title: Why is the interaction energy of the electrons in an atom positive? Consider a simple Hamiltonian for the Helium atom (where $e'^2 = e^2/4\pi \epsilon_0)$:
$H=\frac{P_1^2}{2\mu}+\frac{P_2^2}{2\mu}-\frac{Ze'^2}{R_1}-\frac{Ze'^2}{R_2}+\frac{e'^2}{|\vec{R}_1-\vec{R}_2|}$
I understand the first two kinetic terms are positive because they contribute to the ionization; the second two are negative because they correspond to the attractive potential of the nucleus. But is the third term positive? If I calculate the ground state energy ($-\frac{\mu Z^2e'^4}{2\hbar^2}\sim-Z^2$Ry) without electron interactions, I obtain $\sim-4$ Ry, whereas the experimental value is $\sim-5,8$ Ry, which leads me to conclude that to correct this value the interaction term must be attractive (in order to "attract" the system towards its center), so it should have a minus sign.
However, intuitively, I know the interaction between electrons should be repulsive, and have a positive sign! Your intuition is correct. The error is in your calculation of the ground state energy without interactions. There are two electrons, each with energy $-4\,{\rm Ry}$, for a total of $-8\,{\rm Ry}$. The repulsion raises the energy to the experimental value.
The following is multiple choice question (with options) to answer.
What is the force of attraction between a positive metal ion and valence electrons? | [
"liquid bond",
"galactic bond",
"covalent bond",
"metallic bond"
] | D | A metallic bond is the force of attraction between a positive metal ion and the valence electrons that surround it—both its own valence electrons and those of other ions of the same metal. The ions and electrons form a lattice-like structure. Only metals, such as the copper pictured in the Figure below , form metallic bonds. |
SciQ | SciQ-3508 | pressure, fluid-statics
Title: Why does the water level in a resonance tube increase/decrease as we alter the height of the water reservoir? The resonance apparatus (shown below) is used to calculate the speed of sound using constructive and destructive interference of sound waves.
While conducting the experiment, we continuously vary the length of water column until we achieve resonance.
We alter the length of water in the water column in the following way-
We raise the water reservoir higher than it's original height. The water level in both the tubes (column and reservoir) is seen to increase.
We lower the water reservoir below it's original height. The water level in both the tubes (column and reservoir) is seen to decrease.
This doesn't seem intuitive at all.
- If the water increases in both tubes then where does this extra water come from?
- If the water decreases in both tubes then where does some of the water go?
- Shouldn't liquid stay at the same level? so that the same pressure is maintained?
Further Clarification:
If the length of the height in the water column (BC) be $h$. Then I expect to see the height of the water reservoir also $h$ so that they are at the same level.
Now as we raise the water reservoir, the water level should remain exactly the same (equal to $h$) level. But what happens is the height of the water column and the level of water in the reservoir both increase and become more than $h$.
The opposite happens when we decrease the height of the water reservoir.
All help is appreciated. If both sides are open to the atmosphere as in your diagram, the water stays at the same level on the two sides. The water level moves up or down depending on whether you move the reservoir up or down.
No water appears or disappears. The volume of water stays the same. What changes is the shape of the vessel. Instead of having left and right sides of equal length (as in the diagram on the left below), you are making the reservoir side (on the right) shorter and the cylinder side (left) longer, or vice versa. More importantly you are altering the 'depth' of the connected vessels : the bottom of the connecting tube is moving down or up.
The following is multiple choice question (with options) to answer.
How many times does the height of the largest wave increase with each level? | [
"20 times",
"100 times",
"5 times",
"10 times"
] | D | Richter scale magnitudes jump from one level to the next. The height of the largest wave increases 10 times with each level. So the height of the largest seismic wave of a magnitude 5 quake is 10 times that of a magnitude 4 quake. A magnitude 5 is 100 times that of a magnitude 3 quake. With each level, thirty times more energy is released. A difference of two levels on the Richter scale equals 900 times more released energy. |
SciQ | SciQ-3509 | atmosphere, climate-change, thermodynamics, radiative-transfer
All of which have a compounding effect in the regional and to a lesser degree, global environment, that Chen et al. attribute to as being a cause of a 1-2K temperature rise in high altitude areas in Eurasia and North America and as a disrupting influence in global atmospheric circulation.
Edit 28/2/2016: There is an interesting blog post about a similar phenomenon: Dubai construction alters local climate
Additional references
Chen, B., and G.-Y. Shi, 2012: Estimation of the distribution
of global anthropogenic heat flux. Atmos. Oceanic
Sci. Lett., 5, 108–112.
The following is multiple choice question (with options) to answer.
What does unequal heating of the atmosphere cause? | [
"humidity",
"weather",
"flares",
"water"
] | B | Weather occurs because of unequal heating of the atmosphere. The source of heat is the Sun. The general principles behind weather can be stated simply:. |
SciQ | SciQ-3510 | human-biology, biophysics, skin, light, uv
Title: Can UV radiation be safe for the skin? It is well known that UV radiation can damage the DNA and generally harm our skin.
We also know that UV radiation helps on the production of melanin and Vitamin D.
From what I could find, the DNA absorption spectrum goes to almost zero for wavelengths higher than 300 nm. This seems to suggest that we would be safe to use UV radiation between 300 and 340 nm in our skin (as long as the power or exposure is not too high/long to make burns), for therapeutic purposes such as the stimulation of Vitamin D production.
Is this assumption correct? Are there any evidences that we could use this UV wavelength range safely? You're talking about long-wave UV, or UV-A radiation. In the 80s, experts claimed that this was a safe wavelength. Protection against UV-A was not part of sunscreen in the early days. Consequently, UV-A was (and still is) used in tanning beds due to its perceived safety over UV-B. However, a lot of research has been done since.
UV-A is well understood now to also be unsafe in unreasonable amounts. Currently, UV-A protection is a typical feature of sunscreen and tanning beds are still not a healthy alternative to moderate, healthy doses of sun. Here is a recent review covering some of the aspects comparing different UV range effects on skin. I really suggest you put a search engine to good use here; it makes little sense for us to expound on the literature when it is so clear and easily available.
In summary,
UVA certainly contributes to the development of skin cancer.
UVA penetrates deeper into the skin than UV-B (which is largely responsible for 'burning' of the topmost layer of skin, without directly affecting the deeper layers). For this reason, UV-B is associated primarily with burning and UV-A is primarily associated with aging and aging diseases like cancer.
It is important to note that 95% of UV light in every day life is UV-A, because it does not vary seasonally and can penetrate clouds and windows. Therefore, in spite of the fact that short wavelengths carry more energy per photon, the ratios of UV-A and UV-B exposure are far from equal.
These are only a few of the explanations as to why we observe an incidence of aging and skin damage and disease upon UV-A exposure.
The following is multiple choice question (with options) to answer.
Which vitamin is made in the skin when it is exposed to sunlight? | [
"Vitamin B1",
"vitamin d",
"Riboflavin",
"Vitamin C"
] | B | Some sunlight is good for your health. Vitamin D is made in the skin when it is exposed to sunlight. But getting too much sun can be unhealthy. A sunburn is a burn to the skin that is caused by overexposure to UV radiation from the sun's rays or tanning beds. |
SciQ | SciQ-3511 | molecular-biology, dna, molecular-genetics
Additionally, there's regulation of protein biosynthesis at the ribosome, which often complexes with other molecules in complicated ways to ensure an additional layer of tuning of how much protein is produced, and how quickly.
There are many, many other known levels of regulation. There also remain many unknown mechanisms of regulation, which scientists are busy with uncovering and understanding as we speak.
EDIT: What dictates which protein to synthesize at a given time? The history and present identity of a cell. By identity, I mean its state regarding regulation of its own gene expression, as well as other things.
The following is multiple choice question (with options) to answer.
During protein synthesis, ribosomes assemble what into proteins? | [
"rna acids",
"amino acids",
"DNA Acids",
"polymer acids"
] | B | Figure 4.13 Ribosomes are made up of a large subunit (top) and a small subunit (bottom). During protein synthesis, ribosomes assemble amino acids into proteins. |
SciQ | SciQ-3512 | forces, potential-energy
Title: Force Sans Potential Is it possible to have a force without an associated potential energy? I know when a related potential energy exists, the relationship is $$U = -\int{F(x) dx}$$, but I am curious as to whether the one can exist without the other. If you think of potential energy in the framework of classical mechanics and gravitation, then yes. However...
Presence of force implies energy exchange, whether it is in its explicit form (i.e. a stone falling from the cliff) or implicit (i.e. friction force from the previous answer). A state of philosophical understanding of force these days, as far as I get it, is that any force is mediated by agents: photons, gravitons, gluons etc. These particles carry some form of energy with them and "deliver" it from "sender" to the "recipient", so to say. If one thinks about it this way, there is always some kind of field (potential) present, that mediates interaction. At this point it is the question about definitions, not actual phenomena...
P.S.: in the case of friction, this field is electrostatic.
The following is multiple choice question (with options) to answer.
If particles have enough kinetic energy to completely overcome the force of attraction between them, matter exists as a what? | [
"solid",
"liquid",
"vapor",
"gas"
] | D | If particles have enough kinetic energy to completely overcome the force of attraction between them, matter exists as a gas. The particles can pull apart and spread out. This explains why gases have neither a fixed volume nor a fixed shape. |
SciQ | SciQ-3513 | inorganic-chemistry, redox
Title: Does the reaction of solid Sodium Chlorate and Hydrochloric acid generate Chlorine Dioxide? I did this reaction on a very small scale, swirled it around to mix and react, and saw a yellow green gas come out, as Chlorine gas is one of the products. However, based on what I found online about the reaction I found it ambiguous whether or not it also produced Chlorine dioxide, as it has a similar appearance. Is it maybe dependent on the concentration of HCl, temperature, or pH? (I used 6 M HCl at around room temperature) Sodium chlorate/hydrochloric acid mixture has been actively used as chlorinating agent and Wikipedia did mention that it generates $\ce{HOCl}$ or $\ce{Cl2}$ depending on pH which act as active agent in the chlorination reaction, the reaction does also generate chlorine dioxide. Again, it depends on the kinetics and pH of the reaction system. Following is the abstract from the paper[1]:
The following is multiple choice question (with options) to answer.
Where is chlorine gas produced? | [
"at the anode",
"epidermis",
"in the nucleus",
"carbon cycle"
] | A | It may be logical to assume that the electrolysis of aqueous sodium chloride, called brine , would yield the same result through the same reactions as the process in molten NaCl. However, the reduction reaction that occurs at the cathode does not produce sodium metal because the water is reduced instead. This is because the reduction potential for water is only -0.83 V compared to -2.71 V for the reduction of sodium ions. This makes the reduction of water preferable because its reduction potential is less negative. Chlorine gas is still produced at the anode, just as in the electrolysis of molten NaCl. |
SciQ | SciQ-3514 | computability, turing-machines, physics
Title: Can normal physics laws be simulated in Digital physics? Physics is defined as the study of an object {matter or energy} with its interaction with other objects:
Physics is the study of matter, energy, and the interaction between them.
On the other hand, Digital physics is based on computations and information.
Digital physics is a collection of theoretical perspectives based on the premise that the universe is, at heart, describable by information, and is therefore computable.
The following is multiple choice question (with options) to answer.
What is the study of energy and how it interacts with matter? | [
"physics",
"kinetics",
"quantum mechanics",
"cosmology"
] | A | Physics is the study of energy and how it interacts with matter. Important concepts in physics include motion, forces such as magnetism and gravity, and different forms of energy. Physics concepts can answer all the questions on the right page of the notebook in Figure above . |
SciQ | SciQ-3515 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
What structure of the body falls between cells and organs in complexity? | [
"tissues",
"muscles",
"proteins",
"molecules"
] | A | The human body is organized at different levels, starting with the cell. Cells are organized into tissues, and tissues form organs. Organs are organized into organ systems such as the skeletal and muscular systems. |
SciQ | SciQ-3516 | genetics, evolution, population-genetics, population-biology, allele
Title: Relationship between genetic diversity within and between species Here is a quote from Wagner (2008)
A second line of evidence [against neutralism] comes from the relationship between the mean number of polymorphic differences between alleles within a species, $\pi$, and the number of fixed differences between genes in two species, $d$. For neutral mutations, a positive association between $\pi$ and $d$ should exist, because the neutral theory predicts that both quantities are linearly proportional to the rate at which neutral mutations arise. Recent genome-scale data shows instead that this association is in fact negative.
What do "the mean number of polymorphic differences between alleles within a species" and "the number of fixed differences between genes in two species" have to do with each other? Why should there be any relationship at all? And by "two species", are they talking about Eastern Yellowback Whooping Finches versus Western Yellowback Whooping Finches, or any arbitrary two species, like E. Coli versus Muskrats?
I found this related question, but it doesn't say anything about different species. Metrics of interest
The two metrics you are interested in are
$\pi$ - the mean number of differences between two randomly sampled (with replacement) alleles in a population
$d$ - the mean number of differences between two randomly sampled (with replacement) alleles coming from two different species
Consider two sequences
ATCGTCAAT
ATAGTTAAT
There are 2 pairwise differences between these two sequences (positions 3 and 6).
The whole point here is to understand that two individuals in the same population coalesce at a given time in the past just like two individuals coming from two different species. The number of pairwise differences is just equal to the rate at which mutations accumulate multiplied by the coalescence time. Let me develop this idea with a few equations below.
Neutral Expectations
Let's do the math! We will do two important assumptions below.
Every mutation makes a new allele (it is an infinite allele model)
All mutations are substitutions (no indels, no gene duplication, etc...)
The following is multiple choice question (with options) to answer.
The relationships between groups of different species makes up a ___________. | [
"food chain",
"species",
"community",
"family"
] | C | A community is made up of the relationships between groups of different species. For example, the desert communities consist of rabbits, coyotes, snakes, birds, mice and such plants as sahuaro cactus, ocotillo, and creosote bush. Community structure can be disturbed by such dynamics as fire, human activity, and over-population. |
SciQ | SciQ-3517 | 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.
An offspring that inherits a mutation in a gamete will have the mutation in all of its? | [
"proteins",
"seeds",
"eggs",
"cells"
] | D | Mutations that occur in gametes can be passed on to offspring. An offspring that inherits a mutation in a gamete will have the mutation in all of its cells. |
SciQ | SciQ-3518 | evolution, biochemistry, plant-physiology, plant-anatomy, life
Title: Plants without bacteria? is it theoretically possible? I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But it is a natural way.
But is it possible to have a world with plants (without mammals or microorganisms and without bacteria) that could exist in the long term. Saying the atmosphere of these world has already enough nitrogen, oxygen and CO2, and of course there is water.
What could break this artificially created world with such conditions (say the world created not from low-level living structures)?
Could bacteria emerge in the world? This is the sort of question that should be considered from more than one perspective. Since this is speculation, take it as a given that there is a lot of 'what if' here.
I doubt most animals and plants can do entirely without bacteria - as you say most of the essential nutrients come from bacteria, who fix nitrogen. If only plants were left on earth, eventually the plants would use up all the nitrogen and they would have to find a way to fix more.
Can bacteria emerge from just a world of plants? I don't think viruses arise spontaneously, but since genomes often have viruses embedded in them, over the course of a billion years or so, its possible since bacteria and viruses continue to be impressed upon our genomes. Would it happen in time? Most would be skeptical whether that timing could work out.
In practice it would be hard to create a world like this. I would be interested to see whether you could sterilize the microorganisms off of seeds without killing the plant for instance. If you're asking about a small sterile environment with only plants, you could do it by adding the nutrients the plants need and giving them sunlight. Such self sustaining systems have been made with cyanobacteria and i'd be surprised if plants could not be included. But these are closed systems and judged by limited amounts of time, so whether this is an answer to your question is not clear. Here it looks like some water plants and fish have been done. If there was a plant that created CO₂ at an adequate rate its possible.
The following is multiple choice question (with options) to answer.
How do organisms grow and repair themselves? | [
"cell death",
"symbosis",
"mutation",
"cell division"
] | D | Cell division is how organisms grow and repair themselves. It is also how many organisms produce offspring. For many single-celled organisms, reproduction is a similar process. The parent cell simply divides to form two daughter cells that are identical to the parent. In many other organisms, two parents are involved, and the offspring are not identical to the parents. In fact, each offspring is unique. Look at the family in Figure below . The children resemble their parents, but they are not identical to them. Instead, each has a unique combination of characteristics inherited from both parents. |
SciQ | SciQ-3519 | biochemistry, toxicity, halides
Title: Why are the halogens good disinfectants? I've been searching around the internet for a while and I know that Chlorine, Bromine and Iodine are used as disinfectants.
My question is, what is the property of the halogens that make them suitable for killing microbes? Is it just their toxicity? The halogens, particularly in their diatomic free states and within various oxoacids, are strong oxidizing agents by virtue of their high electronegativities, electron affinities, and reduction potentials. The polarizability of the heavier halogens also makes them almost uniquely versatile as both good leaving groups and strong nucleophiles, depending on conditions. Additionally, the relatively low bond dissociation energies of the halogens contribute to their aptitude to react by free-radical mechanisms (coupled with the exothermicity that usually accompanies the propagation of those reactions).
In their diatomic forms, they readily add across the $\pi$-bonds of alkenes and alkynes (which are ubiquitous and essential structural features of myriad types of biomolecules), and they can oxidize numerous other functional groups under the right conditions and in combination with other substances. Various oxoacids that incorporate halogens are often extremely strong oxidizers as well (household bleach, for example, is an aqueous solution of sodium hypochlorite, which is mild by comparison to certain other halogen-containing oxoacids). In those reactions, they typically serve to add oxygen to molecules in place of, e.g., hydrogen, while themselves serving as leaving groups (or parts of leaving groups).
The following is multiple choice question (with options) to answer.
What do halogens require electrons to achieve? | [
"formation",
"coupling",
"fusion",
"octet"
] | D | Chapter 7 The Periodic Table and Periodic Trends In , we presented the contemporary quantum mechanical model of the atom. In using this model to describe the electronic structures of the elements in order of increasing atomic number, we saw that periodic similarities in electron configuration correlate with periodic similarities in properties, which is the basis for the structure of the periodic table. For example, the noble gases have what is often called filled or closed-shell valence electron configurations. These closed shells are actually filled s and psubshells with a total of eight electrons, which are called octets; helium is an exception, with a closed 1s shell that has only two electrons. Because of their filled valence shells, the noble gases are generally unreactive. In contrast, the alkali metals have a single valence electron outside a closed shell and readily lose this electron to elements that require electrons to achieve an octet, such as the halogens. Thus because of their periodic similarities in electron configuration, atoms in the same column of the periodic table tend to form compounds with the same oxidation states and stoichiometries. ended with the observation that, because all the elements in a column have the same valence electron configuration, the periodic table can be used to find the electron configuration of most of the elements at a glance. |
SciQ | SciQ-3520 | climate-change, earthquakes, glaciology
Title: How significant is human influence on seismic activity? Here's a graph from johnstonsarchive.net showing energy released by earthquakes and, however reliable this graph is, it shows huge differences in earthquake activity. About how big percent is the energy of quakes caused by humans? You have an interesting graph there. In response to your question, I would say that if we actually use the Mw (moment magnitude) measure of seismic activity (which is related to energy release via slip on a fault), we would see that most of the Earthquakes 'caused' by humans (and note that there are still only a few examples of this, (such as the 5.7 Prague, Oklahoma Earthquake), are limited to intraplate earthquakes which only exceed 4 in rare instances such as the above.
The exact 'percent' of energy release due to induced (human-caused) seismicity would probably not even approach single digits, but possibly reside in values approaching zero, when you consider that the vast majority of earthquakes take place at plate boundaries and outnumber induced earthquakes by a large amount.
The following is multiple choice question (with options) to answer.
What is the percentage of earthquakes that take place within a plate, away from plate boundaries? | [
"6%",
"5%",
"4 %",
"3 %"
] | B | About 5% of earthquakes take place within a plate, away from plate boundaries. These intraplate earthquakes are caused by stresses within a plate. Since plates move over a spherical surface, zones of weakness are created. Intraplate earthquakes happen along these zones of weakness. The earthquakes may take place along ancient faults or rift zones. |
SciQ | SciQ-3521 | history, dust
Title: Tongue-in-cheek quote on dust extinction I remember hearing a quote or maybe rather an anecdote about a famous astronomer but I can't recall the exact wording and I also forgot who allegedly said it. Unfortunately, that has thwarted all my googling attempts.
It goes like this:
The retired astronomer gets asked by a journalist if he would do it all again and he replies something along the lines of:
Only if selective to total extinction were constant.
Is this something that really happened? If so, who said it and what is the exact wording?
Please also provide a source if possible. Well, I managed to contact the person I heard this from.
Apparently it was Walter Baade who was asked:
If you had your life to live over, would you be an astronomer again?
To which he answered:
Only if the ratio of total to selective absorption is everywhere the same.
I will not accept this answer as I have not been able to find a source yet. If anyone can find one, feel free to answer and I'll accept.
EDIT: Decided to accept after all, since apparently no one here knows a source. Follow up question regarding the source here.
The following is multiple choice question (with options) to answer.
Despite their name, what scientists study the atmosphere rather than colliding space rocks? | [
"astronauts",
"forecasters",
"meteorologists",
"astronomers"
] | C | Meteorologists don’t study meteors — they study the atmosphere! The word “meteor” refers to things in the air. Meteorology includes the study of weather patterns, clouds, hurricanes, and tornadoes. Meteorology is very important. Using radars and satellites, meteorologists work to predict, or forecast, the weather ( Figure below ). |
SciQ | SciQ-3522 | entomology, proteins, protein-structure
Title: Is the chitin in an insect's exoskeleton cross-linked? This answer to the question How to clean and preserve a cicada's molted exoskeleton (exuvia)? states:
The exuvia is made of cross-liked chitin, and will not decay. You don't need any special preservatives as all. If you need to get the mud off, just rinse it as you said, in soapy water, let it dry, and you are done. Simple.
Wikipedia's Chitin says only:
Chitin is a modified polysaccharide that contains nitrogen; it is synthesized from units of N-acetyl-D-glucosamine (to be precise, 2-(acetylamino)-2-deoxy-D-glucose). These units form covalent β-(1→4)-linkages (like the linkages between glucose units forming cellulose). Therefore, chitin may be described as cellulose with one hydroxyl group on each monomer replaced with an acetyl amine group. This allows for increased hydrogen bonding between adjacent polymers, giving the chitin-polymer matrix increased strength.
I'm not a chemist, but "increased hydrogen bonding between adjacent polymers" doesn't sound the same as cross-linked polymers. So I would like to ask for an answer based on sources other than Wikipedia:
Question: Is the chitin in an insect's exoskeleton cross-linked? If it depends on the type of insect, then the focus should be on "a cicada's molted exoskeleton (exuvia)" as discussed in the linked answer. much like cellulose, chitin strands are bonded to other strands by hydrogen bonds. here is a slide share with a breakdown of the structure.
It is crosslinked in the sense strands are linked to other strands in such a way that most enzymes cannot access it to break it down. this is the same thing that makes wood last untreated. In a strictly chemistry sense it is not a crosslinked polymer (which requires covalent or ionic bonding) but it still has crosslinking. Your hitting a difficulty in jargon.
source.
The following is multiple choice question (with options) to answer.
What is an insect's hard outer exoskeleton made out of? | [
"melanin",
"lectin",
"casein",
"chitin"
] | D | Figure 3.11 Insects have a hard outer exoskeleton made of chitin, a type of polysaccharide. (credit: Louise Docker). |
SciQ | SciQ-3523 | human-biology, biochemistry, molecular-biology, cell-membrane, pulmonology
Title: How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)? How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)?
The vaping illnesses that have been happening on the news in the United States are being caused by the federal prohibition on marijuana. Smugglers will legally go to recreational marijuana dispensaries in legal states and purchase cartridges that contain about a gram of "wax". Proper cartridges will use polyethylene glycol, polypropylene glycol, or vegetable glycerin to suspend the THC for vaporizing, but the smugglers have been known to open up the tank and remove some of the wax and refill the remaining volume with Vitamin E Oil. These tampered cartridges are then sold on the black market to recreational and medical consumers in illegal states.
The CDC Report: "Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products"
Edit: So, I was on some conspiracy shtuff when I wrote this post because I was worried about impurities in my vapes killing me. I don't want to take this down because I want my cognitive distortion to remain visible as a reminder of how we can succumb to biased reasoning. Also, the answer I marked correct contextualized the fragmented information of which I was aware and attempted to give me an improved framework for understanding the terms I was using incorrectly as a layman. There are several ways to get ARDS (sepsis, pneumonia, trauma, pancreatitis, etc). Pathophysiologically, they all converge at alveolar insult. So however it happens, there's alveolar insult, cytokine release that recruits neutrophils, and the activated neutrophils release toxic mediators that destroy the alveolar membranes. So for your question specifically, the mineral oil in the vape cartridges (theoretically) is instigating an inflammatory reaction that destroys alveolar membranes.
The following is multiple choice question (with options) to answer.
What illnesses are caused by damage to the alveoli of the lungs? | [
"pneumonia and emphysema",
"smoking and emphysema",
"chronic and emphysema",
"avian and emphysema"
] | A | Pneumonia and emphysema are caused by damage to the alveoli of the lungs. |
SciQ | SciQ-3524 | species-identification, zoology, entomology
Title: Species identification; clusters of big plump red bugs in Taipei I saw these red insects in Taipei near XinBeitou MRT station in the last week of April 2017, around lunch time. They were fairly active and would keep checking each other out with their antennae for a moment and then move on to the next. What struck me was the wide range of sizes and development in the groups. I didn't notice any feeding or mating that I could recognize, just a lot of walking around and checking each other out.
There are plenty of birds around (this is quite a green area) but I didn't notice any interest by birds in eating them.
I've also included a screenshot from google maps so you can see the location and the trees growing in these concrete structures.
The body of the largest individual is probably 2.5 centimeters long. I'm fairly certain these true bugs belong to the species Leptocoris vicinus, and carry the nickname of "soapberry bugs", which is specific to the subfamily Serinethinae. They're quite common in urban areas of Southeast Asia, which coincides nicely with where you encountered them.
Also, you had mentioned,
There are plenty of birds around (this is quite a green area) but I didn't notice any interest by birds in eating them.
Soapberry bugs, as well as many other types of insects, are able to freely congregate in large numbers, and in such exposed places, due to their bright coloration. Having such a bright color may indicate to some predators that the prey in consideration is toxic, a phenomenon referred to as aposematism.
source
source
And then, here's a map of their distribution, with Taipei holding marker #37. (source)
An interactive version of this map can be found here.
The following is multiple choice question (with options) to answer.
What do you call a group of organisms of the same species that live in the same area? | [
"biosphere",
"population",
"system",
"ecosystem"
] | B | Communities are made up of populations of different species. In biology, a population is a group of organisms of the same species that live in the same area. The population is the unit of natural selection and evolution. How large a population is and how fast it is growing are often used as measures of its health. |
SciQ | SciQ-3525 | dna, dna-sequencing, genomes, human-genome, mouse
I hope this is understandable, if you need any clarification on terms, please ask :)
The following is multiple choice question (with options) to answer.
All the genes in all the members of a population make up its what? | [
"diversity",
"longevity",
"gene pool",
"phenotype"
] | C | A population is a group of organisms of the same species that live in the same area. All the genes in all the members of a population make up the population’s gene pool . For each gene, the gene pool includes all the different alleles in the population. The gene pool can be described by its allele frequencies for specific genes. The frequency of an allele is the number of copies of that allele divided by the total number of alleles for the gene in the gene pool. |
SciQ | SciQ-3526 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
Although some have suggested that the uvula is what type of organ, it actually serves an important purpose? | [
"remnant",
"vestigial",
"essential",
"parietal"
] | B | A fleshy bead of tissue called the uvula drops down from the center of the posterior edge of the soft palate. Although some have suggested that the uvula is a vestigial organ, it serves an important purpose. When you swallow, the soft palate and uvula move upward, helping to keep foods and liquid from entering the nasal cavity. Unfortunately, it can also contribute to the sound produced by snoring. Two muscular folds extend downward from the soft palate, on either side of the uvula. Toward the front, the palatoglossal arch lies next to the base of the tongue; behind it, the palatopharyngeal arch forms the superior and lateral margins of the fauces. Between these two arches are the palatine tonsils, clusters of lymphoid tissue that protect the pharynx. The lingual tonsils are located at the base of the tongue. |
SciQ | SciQ-3527 | ecology, biogeography
Edit in response to comments
Comment about biome scale
The reason behind the scale comment is that typically we observe succession for a given habitat. Part of this stems from the origin of the succession ideas, where Frederic Clements posited that climate was the major driving factor of successional trajectories (Clements 1916). This would actually fit well with the biome view of succession, however in order for this model to explain all the variation we see in the world (eg. why a tree grows in location X but not location Y 4 metres away), you devolve into splitting the world into infinitesimally small micro-climates. Henry Gleason proposed a more individualistic model, which suggested that climate was just one influence, and that each plant species responds to a myriad of different environmental cues (Gleason 1927). The sum of these responses results in the community at a given location. This seems to fit better with our current understanding of succession but is not without problems. In a Gleasonian model, any variation can be expected to result in a different community. Since it would be strange for the pampas region to be homogeneous over 1.2 million km2, there are likely distinct communities within the biome, each developing as a result of factors like soil moisture, soil chemistry, climate, wind exposure, and herbivore use. One can still talk about succession at a biome scale, but at that scale we would be thinking about what factors lead the pampas region to become a grassland, rather than what factors lead grass X, tree Y and forb Z to coexist next to each other.
Factors maintaining grassland type ecosystems are fairly uniform globally. You need some sort of event that will kill woody vegetation but not kill grasses and forbs. Fire and grazing are natural examples (Briggs et al. 2002), but mowing would also maintain grassland (Fidelis et al. 2012). Earthquakes are unlikely to maintain grassland as trees and shrubs are likely to survive earthquakes.
Comment about global pampas
The following is multiple choice question (with options) to answer.
The differences in the biomes is due to differences in the what factors? | [
"abiotic",
"temperature",
"air quality",
"biological"
] | A | The differences in the biomes are due to differences in the abiotic factors , especially climate. Climate is the typical weather in an area over a long period of time. The climate includes the amount of rainfall and the average temperature in the region. Obviously, the climate in the desert is much different than the climate in the rainforest. As a result, different types of plants and animals live in each biome. |
SciQ | SciQ-3528 | genetics, gene-expression, human-genetics, mitochondria, gene
Title: Father with mutated mtDNA- why isn't his offspring at risk? Mothers transmit their mitochondria (and therefore mtDNA) to their offspring and fathers don't. Lets assume that father had a mutation of the gene that encodes mtDNA, would then be his offspring at risk? Why?
I also found the following statement:
"The current genetic advice is that fathers with mtDNA mutations are at no risk of transmitting the defect to their offspring."
How can that be true? Is it because of gene silencing?
Thank you in advance!
...would then be his offspring at risk? Why?
No. Generally speaking, fathers do not pass on their mtDNA (Mitochondrial DNA).
Why? Because the mitochondria present in oocytes (egg cell) is the mother's, as every oocyte directly inherits the mother's mitochondria when they are made in the reproductive organs. The mitochondria that the sperm from the father carry to the egg do not enter the egg cell or are destroyed in the process.
It's also worth mentioning that, in general, mtDNA does NOT reside in the nucleus of cells, but in the mitochondria itself. It is not condensed during cell division, it is not spliced during Meiosis II, and it does not undergo recombination with another cell's mtDNA. Instead, when a cell divides, each cell takes about half of the mitochondria present in the cell and maintains them. That way only the mitochondria present in the cell before division will be inherited by the daughter cells, and thus only the maternal mitochondria present in oocytes (egg cells) before sperm instigate cell division will be inherited by any offspring.
The following is multiple choice question (with options) to answer.
What increases the chances of someone inheriting a mitochondrial disease? | [
"presence of defect mtdna and undefected mtdna",
"presence of defect transgenic and defect mtdna",
"presence of defect transgenic and undefected mtdna",
"presence of defect ornithopods and undefected mtdna"
] | A | Unfortunately, maternal mt(DNA)is susceptible to mutations which are a cause of inherited disease, such as breast cancer. Although, it is important to note that most mutations do not lead to defected mtDNA. Heteroplasmy is the presence of a mixture of more than one type of mtDNA. Most people have homoplasmic cells, meaning that their cells contain only normal, undefected mtDNA. However, people with both normal, undefected mtDNA and not normal, defected mtDNA, may inherit mitochondrial diseases. The ultimate condition leading to disease is when the proportion of mutant mtDNA reaches a threshold, after which the cell can no longer cope, resulting in disease. This threshold varies among different tissues and different mutations. |
SciQ | SciQ-3529 | genetics, human-genetics, population-genetics, twins
Title: Why was the study of "Concordance of Monozygotic and Dizygotic twins for traits" designed in this way? I am confused by the twin study 'Concordance of Monozygotic and Dizygotic twins for traits.' My questions arose from 3:17-4:17 of the video
And this is the related data I have referred
I have the following questions:
1 Is the dizygotic twins also separated in different families? If true, didn't the DZ group lack the Control Variables of 'same environment 'or'identical genes'? Or should we make the '50% identical genes' as control variables?
2 why do we need Dizygotic-Twin groups in the experiment, if we need to find the environmental influences why not just find a pair of unrelated individuals and set them at a same family (environment)? Alternatively, is it necessary to compare the monozygotic groups with dizygotic groups instead of any others that aren't dizygotic twins? My interpretation of the first question is why do traits determined by the environment appear to be equally similar among monozygotic and dizygotic twins in these twin studies. The studies he is talking about look at twins that are separated and adopted in to different families. These different families provide a different environment for either twin, and with enough samples, you can compare similarity between dizygotic and identical twins. So imagine you measure the trait of interest (height) in all individuals, and find that identical twins more closely resemble each other than dizygotic twins do. This would indicate that height is somewhat genetically determined - the more genetically similar pairs were more phenotypically similar.
The following is multiple choice question (with options) to answer.
What is often the cause of phenotypic differences between identical twins? | [
"genetics",
"natural selection",
"learned behavior",
"environment"
] | D | Scientists often study the effects of environment on phenotype by studying identical twins. Identical twins have the same genes, so phenotypic differences between twins often have an environmental cause. Twin studies help understand the relative importance of environmental and genetic influences on individual traits and behaviors. Twins are a valuable source of information concerning the relationship between genes and environment. As monozygotic twins (identical) share their nuclear DNA, their polymorphisms , the nucleotide differences that make their DNA unique, are common to the two individuals. This means that any phenotypic variation, such as in height, intelligence, or any other measurable trait, is due to the environment. What is different about the experiences of the twins? What unique experiences might one twin have that the other twin did not have? By comparing phenotypes of hundreds of twins, researchers can understand the roles of genetics, shared environment and unique experiences in the formation and development of specific traits. |
SciQ | SciQ-3530 | newtonian-mechanics, forces, free-body-diagram, gas
* Incidentally, this is the wording I have found most beneficial for understanding Newtonian forces. Instead of saying "every action has an equal and opposite reaction," and trying to figure out which is the action and which is the reaction in every case, I like to say "forces come in equal but opposite pairs, one acting on one body and one acting on the other." There's nothing special about which one is the action and which is the reaction. They simply come in pairs. Call one of them the action if it helps with understanding, simply to help anchor your own intuition.
The following is multiple choice question (with options) to answer.
What kind of equal and opposite forces cancel one another out when they act on the same object? | [
"balanced",
"combined",
"exact",
"solid"
] | A | You might think that actions and reactions would cancel each other out like balanced forces do. Balanced forces, which are also equal and opposite, cancel each other out because they act on the same object. Action and reaction forces, in contrast, act on different objects, so they don’t cancel each other out and, in fact, often result in motion. For example, in Figure above , the kangaroo’s action acts on the ground, but the ground’s reaction acts on the kangaroo. As a result, the kangaroo jumps away from the ground. One of the action-reaction examples in the Figure above does not result in motion. Do you know which one it is?. |
SciQ | SciQ-3531 | genetics, human-genetics, population-genetics, twins
Title: Why was the study of "Concordance of Monozygotic and Dizygotic twins for traits" designed in this way? I am confused by the twin study 'Concordance of Monozygotic and Dizygotic twins for traits.' My questions arose from 3:17-4:17 of the video
And this is the related data I have referred
I have the following questions:
1 Is the dizygotic twins also separated in different families? If true, didn't the DZ group lack the Control Variables of 'same environment 'or'identical genes'? Or should we make the '50% identical genes' as control variables?
2 why do we need Dizygotic-Twin groups in the experiment, if we need to find the environmental influences why not just find a pair of unrelated individuals and set them at a same family (environment)? Alternatively, is it necessary to compare the monozygotic groups with dizygotic groups instead of any others that aren't dizygotic twins? My interpretation of the first question is why do traits determined by the environment appear to be equally similar among monozygotic and dizygotic twins in these twin studies. The studies he is talking about look at twins that are separated and adopted in to different families. These different families provide a different environment for either twin, and with enough samples, you can compare similarity between dizygotic and identical twins. So imagine you measure the trait of interest (height) in all individuals, and find that identical twins more closely resemble each other than dizygotic twins do. This would indicate that height is somewhat genetically determined - the more genetically similar pairs were more phenotypically similar.
The following is multiple choice question (with options) to answer.
What are two other terms for dizygotic twins, which make good study subjects because they share many environmental conditions, but only about half of their polymorphisms? | [
"fractional",
"fraternal, non-identical",
"interdependant twins",
"identical twins"
] | B | Dizygotic twins (fraternal or non-identical) share only about half of their polymorphisms. These twins are helpful to study as they tend to share many aspects of their environment. As they are born in the same place, usually within a few minutes of each other, they share many environmental conditions. They had the same in utero environment, they usually have a similar or the same parenting style during their childhood, and a similar or the same education. Similarities during childhood usually occur with wealth, culture, and their community. |
SciQ | SciQ-3532 | cancer, mutations
Here is another great paper that specifically addresses your question, linking increased cell division with the accumulation of both significant and insignificant mutations, which over time, lead to an accumulation of mutations needed for cancer to develop.
The following is multiple choice question (with options) to answer.
Many diseases arise from genetic mutations that prevent the synthesis of critical what? | [
"lipids",
"acids",
"oils",
"proteins"
] | D | Geneticist Many diseases arise from genetic mutations that prevent the synthesis of critical proteins. One such disease is Lowe disease (also called oculocerebrorenal syndrome, because it affects the eyes, brain, and kidneys). In Lowe disease, there is a deficiency in an enzyme localized to the Golgi apparatus. Children with Lowe disease are born with cataracts, typically develop kidney disease after the first year of life, and may have impaired mental abilities. Lowe disease is a genetic disease caused by a mutation on the X chromosome. The X chromosome is one of the two human sex chromosome, as these chromosomes determine a person's sex. Females possess two X chromosomes while males possess one X and one Y chromosome. In females, the genes on only one of the two X chromosomes are expressed. Therefore, females who carry the Lowe disease gene on one of their X chromosomes have a 50/50 chance of having the disease. However, males only have one X chromosome and the genes on this chromosome are always expressed. Therefore, males will always have Lowe disease if their X chromosome carries the Lowe disease gene. The location of the mutated gene, as well as the locations of many other mutations that cause genetic diseases, has now been identified. Through prenatal testing, a woman can find out if the fetus she is carrying may be afflicted with one of several genetic diseases. Geneticists analyze the results of prenatal genetic tests and may counsel pregnant women on available options. They may also conduct genetic research that leads to new drugs or foods, or perform DNA analyses that are used in forensic investigations. |
SciQ | SciQ-3533 | human-biology, senescence
Title: Could inhibition of progerin formation slow the rate at which a body ages? According to wikipedia, progerin is activated in senescent cells. The protein itself is known to be the cause of a rare affliction 'progeria' - a disease marked by accelerated aging of the body. This disease is not accompanied by neurodegeneration.
Is progerin the key factor in the aging process?
If yes, could inhibition of progerin formation control the rate at which a body ages? Progeria (and related) syndromes are essentially a collection of 'accelerated aging' phenotypes caused by single mutations; Progerin is a shortened version of the protein Lamin A, and is therefore not found in individuals without a loss-of-function mutation in the LMNA gene (the wiki page you reference). As far as we are aware these genes do not 'cause' aging in individuals without the mutations.
LMNA is a normal component of the nuclear lamina (a structure inherent to the nucleus). This review discusses the various diseases associated with mutations in this gene, some of which present 'accelerated aging' phenotypes. However, as far as I know, there is limited evidence to suggest that LMNA, or indeed any Lamina associated protein, is involved in 'normal aging'. A recent GWAS meta-analysis found a variant in LMNA that is associated with longevity in humans, however the association is relatively weak (OR=1.18, P=7(x10)-4), so even if this is a true association, it seems that (as usual in aging research) there are many other factors to consider, and it is not a single gene that is doing the aging.
So to stress the point: progerin has no function in 'normal' human aging - it is a defective protein caused by a germline (or novel) mutation in the LMNA gene. Accelerated aging is the symptom of this genetic disorder, and is not completely analogous to normal aging (as you point out, there is no cognitive decline that is associated with normal human aging).
The following is multiple choice question (with options) to answer.
Pseudohypertrophic muscular dystrophy is an inherited disorder that causes gradual deterioration of what? | [
"nerves",
"brain",
"muscles",
"fluids"
] | C | |
SciQ | SciQ-3534 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
Plants obtain their energy from the sun through photosynthesis , what do animals obtain their energy from? | [
"ultraviolet rays",
"proteins",
"organisms",
"tissues"
] | C | All organisms have the ability to grow and reproduce. To grow and reproduce, organisms must get materials and energy from the environment. Plants obtain their energy from the sun through photosynthesis , whereas animals obtain their energy from other organisms. Either way, these plants and animals, as well as the bacteria and fungi, are constantly interacting with other species as well as the non-living parts of their ecosystem. |
SciQ | SciQ-3535 | human-biology, human-anatomy, human-ear
Title: What is the course of inter auricular line? BACKGROUND: The interauricular line is the line connecting two auricles.
I wish to know the exact route through which this line passes. I want to be sure whether it passes through the parietal prominences, or in front of them. Up front - I have never heard of this term and I could not find information on the interauricular line. The only thing I was able to dig up was the term auricular line, which is (Fig. 1):
[The] [l]ine pass[ing] perpendicular to the anthropological baseline,
through the cent[er] of the external auditory meatus.
Fig. 1. Auricular line. source: Radiology Key
The anthropological line being (Fig. 2):
[The] [l]ine join[ing] the infraorbital margin to the superior border
of the external auditory meatus.
Fig. 2. Anthropological line. source: Radiology Key
The following is multiple choice question (with options) to answer.
What type of fibrous joint is found between most bones of the skull? | [
"trecature",
"suture",
"lobiture",
"aperture"
] | B | 9.2 | Fibrous Joints By the end of this section, you will be able to: • Describe the structural features of fibrous joints • Distinguish between a suture, syndesmosis, and gomphosis • Give an example of each type of fibrous joint At a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them (Figure 9.5). The gap between the bones may be narrow or wide. There are three types of fibrous joints. A suture is the narrow fibrous joint found between most bones of the skull. At a syndesmosis joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a ligament or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. Lastly, a gomphosis is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits. |
SciQ | SciQ-3536 | behaviour, language, genetic-code
Title: How does DNA encode high level features like animal behaviour and language? We know there are complex features which animals supposed to develop based on their genes as opposed to learning from the environment and the collective, also sometimes being very specific to certain species:
Concepts how to build homes
Animal languages including social insect interactions responsible for information transmission (or do they have to learn them through an acquisition process, let's exclude languages of ape tribes where "term" creation has been demonstrated?)
Valid answer: if already known, one or to examples to corresponding research.
Constraint: we are not talking about genes responsible for some sort of tendencies in behaviour but situations where there seems to be a more or less complex "blue print". I suppose we are yet very far from understanding these things. Relation of genotype to phenotype is teh subject of much contemporary research, but it is mainly limited to simple phenotypic features, explainable by action of a few genes, such as the colors of zebra fish mutants: see, e.g., this paper and the related publications by Nüsseln-Vollhardt group. Perhaps closer to your question is circadian rythms, which also have genetic determinants.
The complex behaviors are likely a result of the complex interactions of many genes, which are a very interesting, but also a very difficult problem to solve.
The following is multiple choice question (with options) to answer.
Innate behaviors occur in all animals. however, they are less common in species with higher levels of what? | [
"hormones",
"intelligence",
"interdependence",
"nonverbal communication"
] | B | Innate behaviors occur in all animals. However, they are less common in species with higher levels of intelligence. Humans are the most intelligent species, and they have very few innate behaviors. The only innate behaviors in humans are reflexes. A reflex is a response that always occurs when a certain stimulus is present. For example, a human infant will grasp an object, such as a finger, that is placed in its palm. The infant has no control over this reaction because it is innate. Other than reflexes such as this, human behaviors are learned–or at least influenced by experience—rather than being innate. |
SciQ | SciQ-3537 | periodic-table, history-of-chemistry
Title: Why lanthanides and actinides are shown separate from standard Periodic Table layout? In the standard Periodic Table layout , all the elements up to 56 are in order i.e are in the same layout table. However, lanthanides and actinides are always shown separately from the layout like in this layout:
What is the reason behind this structure?
Is this standard layout or can I represent it like this too? The Periodic Table arranges elements in blocks as each type of orbital fills with electrons - $s,p,d,f,g,h$. Alkali metals and alkaline earths are $s$-block filling (but could be one $s$-block slot). $p$-block six electrons to fill are trelides, tetralides, pnticides, chalcogenides, halides, inert gases (but could be one $p$-block slot). Transition metal $d$-block is ten elements (but could be one $d$-block slot). Filling the $f$-block are 14 elements, lanthanoids and actinoids. That gets sloppy to print and the elements are (or at least were) overall obscure. They get condensed.
Representing the Periodic Table has become an an art form. The plain vanilla variety is terse and useful.
http://en.wikipedia.org/wiki/Alternative_periodic_tables
The following is multiple choice question (with options) to answer.
The periodic table is an arrangement of the elements in order of increasing what? | [
"metallic numbers",
"atomic numbers",
"gravity numbers",
"negative numbers"
] | B | Summary The periodic table is an arrangement of the elements in order of increasing atomic number. Elements that exhibit similar chemistry appear in vertical columns calledgroups (numbered 1–18 from left to right); the seven horizontal rows are calledperiods. Some of the groups have widely used common names, including thealkali metals (group 1) and the alkaline earth metals (group 2) on the far left, and the halogens (group 17) and the noble gases (group 18) on the far right. The elements can be broadly divided into metals, nonmetals, and semimetals. Semimetals exhibit properties intermediate between those of metals and nonmetals. Metals are located on the left of the periodic table, and nonmetals are located on the upper right. They are separated by a diagonal band of semimetals. Metals are lustrous, good conductors of electricity, and readily shaped (they areductile and malleable), whereas solid nonmetals are generally brittle and poor electrical conductors. Other important groupings of elements in the periodic table are the main group elements, the transition metals, the lanthanides, and the actinides. |
SciQ | SciQ-3538 | photosynthesis, membrane-transport, energy-metabolism
A more recent (2013) paper from the same group considers the proton transfer pathway in cytochrome b6f in more depth, and I reproduce below Fig. 1B from that paper to indicate the type of molecular detail.
Heavy reading, but wonderful stuff!
The following is multiple choice question (with options) to answer.
What type of ions play critical roles in light-dependent reactions? | [
"silicon",
"helium",
"calcium",
"hydrogen"
] | D | The replacing of the electron enables chlorophyll to respond to another photon. The oxygen molecules produced as byproducts find their way to the surrounding environment. The hydrogen ions play critical roles in the remainder of the light-dependent reactions. Keep in mind that the purpose of the light-dependent reactions is to convert solar energy into chemical carriers that will be used in the Calvin cycle. In eukaryotes and some prokaryotes, two photosystems exist. The first is called photosystem II, which was named for the order of its discovery rather than for the order of the function. After the photon hits, photosystem II transfers the free electron to the first in a series of proteins inside the thylakoid membrane called the electron transport chain. As the electron passes along these proteins, energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space. This is quite analogous to the process that occurs in the mitochondrion in which an electron transport chain pumps hydrogen ions from the mitochondrial stroma across the inner membrane and into the intermembrane space, creating an electrochemical gradient. After the energy is used, the electron is accepted by a pigment molecule in the next photosystem, which is called photosystem I (Figure 5.13). |
SciQ | SciQ-3539 | atmospheric-science, density, air
Title: Why does the composition of the air does not change with altitude? Air contains about 78% nitrogen and 21% oxygen independent of altitude (up to 100 km). Why is this? Shouldn't the concentration of nitrogen increase with higher altitudes since nitrogen has a lower density than oxygen?
Shouldn't the concentration of nitrogen increase with higher altitudes since nitrogen has a lower density than oxygen?
No, it shouldn't, at least not up to 100 km or so. Look at your graph, which shows that even argon is well-mixed throughout the lower atmosphere (the troposphere, stratosphere, and mesosphere). Argon atoms are considerably more massive than are carbon dioxide molecules, which in turn are considerably more massive than oxygen and nitrogen molecules, and yet all of these (along with all of the long-lived gases in the atmosphere) are well-mixed throughout the lower atmosphere.
The reason is that the lower atmosphere is dense enough to support turbulence while the upper atmosphere is not. The turbopause marks the somewhat fuzzy boundary below which turbulent mixing dominates over diffusion and above which it's diffusion that dominates.
The following is multiple choice question (with options) to answer.
What moves nitrogen back and forth between the atmosphere and organisms? | [
"the nitrogen cycle",
"the calcium cycle",
"the Krebs cycle",
"the leakage cycle"
] | A | The nitrogen cycle moves nitrogen back and forth between the atmosphere and organisms. |
SciQ | SciQ-3540 | meteorology, atmosphere, wind, air-currents
Title: Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.
What forces would cause such a mass movement of air? Wind is caused by pressure differences. Think of a balloon full of air; poke a hole in it and the air comes out. Why? Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.
There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role. The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:
$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$
In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.
The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel). The RHS represent a number of factors that produce a change in the wind. From left to right:
Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)
The following is multiple choice question (with options) to answer.
What is caused by human actions that releases chemical substances and particles into the air? | [
"heavy pollution",
"Improper Emissions",
"CFO pollution",
"air pollution"
] | D | Recall that air pollution is due to chemical substances and particles released into the air mainly by human actions. When most people think of air pollution, they think of the pollution outdoors. But it is just as easy to have indoor air pollution. Your home or school classroom probably doesn't get much fresh air. Sealing up your home reduces heating and cooling costs. But this also causes air pollution to stay trapped indoors. And people today usually spend a majority of their time indoors. So exposure to indoor air pollution can become a significant health risk. |
SciQ | SciQ-3541 | immunology, lab-techniques, flow-cytometry, cell-sorting
Without lysis, the RBCs overwhelm the cytometer, as they make up around 95% of the cells in human whole blood. White blood cells (leukocytes), on the other hand, only make up 0.1-0.2% of cells, and lymphocytes between about 15 to 50% of leukocytes.
The cell mixture is then analyzed on a cell sorter such as a BD FACSAria.
From: https://commons.wikimedia.org/wiki/File:Fluorescence_Assisted_Cell_Sorting_%28FACS%29_B.jpg
The cells pass in single file past one or more laser beams, which excite the dyes and cause them to fluoresce at a certain wavelength. The user can then use gating to select the combination and intensity of colors they are interested in, and when a cell meets the criteria, it is given an electrical charge, and electro magnets direct it into a collection container.
The following is multiple choice question (with options) to answer.
The human body has as many as two trillion lymphocytes, and lymphocytes make up about 25% of all of what? | [
"red blood cells",
"pathogens",
"glands",
"leukocytes"
] | D | The human body has as many as two trillion lymphocytes, and lymphocytes make up about 25% of all leukocytes. The majority of lymphocytes are found in the lymphatic system, where they are most likely to encounter pathogens. The rest are found in the blood. There are two major types of lymphocytes, called B cells and T cells. These cells get their names from the organs in which they mature. B cells mature in bone marrow, and T cells mature in the thymus. Both B and T cells recognize and respond to particular pathogens. |
SciQ | SciQ-3542 | sensation, olfaction
http://www.comeaddestrareuncane.com/blog/tag/cani-molecolari/
In the dog, the surface of the olfactory mucosa varies between 70 and 150 cm2 - in this tissue the number of olfactory receptors varies from 250 to 280 million - In 1962, Becker et al. showed that dogs are able to recognize substances in dilutions from 1/100 to 1/10.000.000.
- http://milano.corriere.it/milano/notizie/cronaca/12_febbraio_19/cani-olfatto-parere-esperto-1903358352720.shtml
Have you noticed how a dog sniffs the urine of a female "tasting it"? It is the same action that makes the viper when it follows the track of the mouse: it evertes the tongue and carries on it the odorous particles in the buccal cavity, and this organ has a function in the middle between the olfactory and gustatory ones. "Pointing dogs" is as pointing "the wild" taste the smell.
"Eat the scent", in the jargon, because savored, not only in terms of smell, the smell of the wild. The Jacobson's organ is then a second organ capable of perceiving odors, the first we've said is represented ciliated epithelium of the mucous membrane of the nose.
But there is a third organ called the "Rodolfo-Masera" which also serves to sense the emanations chemical (not yet known which), that way you could explain a specialization of these organs to perceive certain groups of biochemicals than others.
- http://www.laciotola.net/Cani/la-funzione-olfattiva-del-cane.html
The following is multiple choice question (with options) to answer.
What chemical substances are secreted by animals that communicate by odor or taste? | [
"alaki",
"hormones",
"pheromones",
"acids"
] | C | |
SciQ | SciQ-3543 | power-engineering
Title: Why are hydropower plants always wheel-shaped and not flat? Question:
Why are there no flat power generators like in the picture below, that work on the surface of shallow, but steadily flowing rivers ? (As a floating micropower plant.)
The picture shows a conveyer belt with vanes/blades(?) attached to it. The water flow moves the conveyer belt. A generator could be attached to the front and back "wheel" of the belt.
Here's a video of something similar. I would just build it on a larger river.
Why would I ask this?
There are much more flat rivers than waterfall-like structures on this planet. Using them looks like a much more non-nature-inversive, cheap solution. Having a longer surface should supply better drag by flowing water. When you want to solve a problem, the best start is to look at previous attempts. To provide some perspective, I'm doing that for you now. You are not looking at a typical hydro power plant where a dam provides a high head, and the flow is ducted onto a a francis or pelton turbine. You are describing a microhydropower installation with a floating turbine.
Floating hydrpower allows capturing some power without building a dam. The turbine could be placed in or near the middle of the river, where the current is fastest. An installation with a damn will always harvest vastly more power from the same river.
Before electrical power transmission became widespread, there used to be boat mills - workshops with machinery driven by water wheels, placed on boats.
(Boat mill in Servia, 1900, Image from lowtechmagazine page on boat mills)
Improvised versions have also been used for electricity generation.
Floating hydro power is, AFAICT, an ongoing area of developement. The two most common turbine shapes appear to be a propeller hanging from buoys:
(Image source)
... Or some sort of flat paddle wheel:
Vertical axis turbines also exist.
I think Kamran explains quite well why a propeller or a paddle wheel is used, rather than a conveyor belt. I will just add this: Look at the water wheel in the direction of flow: You want to maximise area here.
The following is multiple choice question (with options) to answer.
Hydropower is generated with what natural resource? | [
"air",
"light",
"fire",
"water"
] | D | Hydropower utilizes the energy of falling water. |
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