source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3844 | metabolism, nutrition, digestive-system
Title: Do I have to chew for digestion to kick in? Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"? If you had to chew to digest, then beverages like sugary sodas would never be digested or provide calories or nutrients, as you (generally) don't chew when you drink them. No, chewing is not required for digestion or nutrient absorption. Chewing is important when eating solid foods, as the chewing action breaks down and begins to solublize the food, and stimulates the production of saliva, which contains enzymes that begin to break down the food prior to digestion in the stomach and intestines.
The following is multiple choice question (with options) to answer.
What type of digestion is chewing an example of? | [
"electromagnetic",
"fluid",
"gravity",
"mechanical"
] | D | |
SciQ | SciQ-3845 | asteroids, comets, extinction
This is somewhat doable, but quickly get complex (different populations, orbits are not actually evenly distributed, etc.) A better approach may simply be to look at the past impacts causing extinctions! Depending on how you count, there has been one known mass extinction due to impacts since the Cambrian 538.8 mya, so the rate might be on the order of $2\cdot 10^{-9}$ per year. But that likely leaves out a fair number of minor extinctions. If we assume all Big 5 were due to impacts the rate becomes $9\cdot 10^{-9}$ per year.
Incidentally, to get these values in the above formula for the assumed values, $N$ should be in the range 0.2 to 1.
Obviously this can be improved: we can use statistical modelling to get error bars, we can use the known size distribution of asteroids (a power law) to estimate the fraction of Earth-crossers and long-periodic comets that could be bad and their inflow rate, and so on. But that misses the Drake equation approach of trying to find a quick-and-dirty model that shows the key variables we care about and might want to estimate.
The following is multiple choice question (with options) to answer.
How many major massive extinctions have been since life began on earth? | [
"one",
"four",
"five",
"three"
] | C | Since life began on Earth, there have been at least five major massive extinctions. |
SciQ | SciQ-3846 | evolution, bioinformatics, sequence-analysis, methods, systems-biology
Title: Is there a system biology approach to compare pathways or famillies of proteins from an evolutionary point of view for the same organism? I would be interested to know if there is a method/analysis or a set of methods to compare two groups of pathways or families of proteins.
I would specifically be interested by a system biology approach which takes all the components of the pathway or family of proteins. I would like to know if there is a method which can not only compare the similarity, homology, divergence and convergence of a family of proteins (like ribosomal proteins) between species but also between groups in the same organism.
For example I would like to compare the molecular components of vesicular trafficking pathways to the molecular components of non-vesicular pathway in the same organism saccharomyces cerevisiae (yeast).
I would greatly appreciate your suggestions. I am not sure that I completely understand, it would be a little easier if you described the problem you are trying to solve or what the motivation is.
However, I think that some of what you want to do can be accomplished by inferring gene/protein trees for each gene/protein of interest across different species (including paralogs, maybe?). This will allow you to see discordance or correlation of evolutionary rates of different genes/proteins across species.
THis kind of analysis is built into HyPhy, though I have never used it. There are also somewhat less involved methods for measuring distances between trees.
You might also be interested in protein co-evolution methods, depending on the question at hand.
Your mentioning systems biology methods suggests that you have something rather different in mind, as none of these things I suggest are really systems biology IMO, but I'm not sure what it would be. Possibly you are interested in integrating e.g. protein-protein interaction or metabolic network information as well, but that would probably involve something more homebrewed that might integrate some of these things.
Hope that helps.
The following is multiple choice question (with options) to answer.
What tool do scientist's use to show the evolutionary pathways and connections among organisms? | [
"superficial tree",
"photogenetic tree",
"conceptual tree",
"phylogenetic tree"
] | D | Phylogenetic Trees Scientists use a tool called a phylogenetic tree to show the evolutionary pathways and connections among organisms. A phylogenetic tree is a diagram used to reflect evolutionary relationships among organisms or groups of organisms. Scientists consider phylogenetic trees to be a hypothesis of the evolutionary past since one cannot go back to confirm the proposed relationships. In other words, a “tree of life” can be constructed to illustrate when different organisms evolved and to show the relationships among different organisms (Figure 20.2). Unlike a taxonomic classification diagram, a phylogenetic tree can be read like a map of evolutionary history. Many phylogenetic trees have a single lineage at the base representing a common ancestor. Scientists call such trees rooted, which means there is a single ancestral lineage (typically drawn from the bottom or left) to which all organisms represented in the diagram relate. Notice in the rooted phylogenetic tree that the three domains— Bacteria, Archaea, and Eukarya—diverge from a single point and branch off. The small branch that plants and animals (including humans) occupy in this diagram shows how recent and miniscule these groups are compared with other organisms. Unrooted trees don’t show a common ancestor but do show relationships among species. |
SciQ | SciQ-3847 | organic-chemistry, food-chemistry, fats
Title: Saturated vs unsaturated fats - Structure in relation to room temperature state? I'm sure most of us have heard that saturated fats are solid at room temperature, and unsaturated fats are liquid at room temperature. I'm wondering how this relates to their chemical structure -- saturated fats contain only single bonds between carbons, yet to qualify as an unsaturated fat a C=C double bond must exist.
Since a double bond is stronger than a single bond, and the length of the C=C double bond is shorter than that of the single bond, why is it that the fat containing a double bond is a liquid and saturated fats are solids at room temperature? Seems like the double bond would inhibit movement and the resulting substance would be less like olive oil and more like butter. In the solid state, the individual triacylglycerol molecules are interacting with each other primarily through Van der Waals interaction. These weak bonds between molecules are broken at the solid-liquid transition. The amount of energy needed to disrupt these interactions (which determines the melting point of the fat or oil) is determined by the energy associated with all of these bonds added together. In a saturated fat, the acyl chains are able to align perfectly right along their length, maximizing intermolecular interactions. This effect is reflected in the fact that the melting temperature of a pure triacylglycerol increases as the chain length increases.
You can see this effect clearly in the melting temperatures of individual fatty acids. (C18:0 means an 18 carbon molecule with zero double bonds in the acyl chain):
C18:0 (stearic acid) 70°C
C16:0 (palmitic acid) 63°C
C14:0 (myristic acid) 58°C
So the addition of a single -CH2- group in the acyl chain increases melting temperature by a few degrees.
When a cis double bond is introduced into the acyl chain this creates a kink in the structure. Because of this, the acyl chains cannot align completely along their length - they don't pack together as well. Because of this, the sum of the energy associated with intermolecular Van der Waals interactions is reduced. Again this is seen clearly in the melting temperatures of fatty acids:
stearic acid C18:0 70°C
oleic acid C18:1 16°C
The following is multiple choice question (with options) to answer.
What kind of bonds are there between carbon atoms in saturated fatty acids? | [
"single",
"double",
"chemical",
"electrical"
] | A | In saturated fatty acids, there are only single bonds between carbon atoms. As a result, the carbons are saturated with hydrogen atoms. Saturated fatty acids are found in fats. Fats are solid lipids that animals use to store energy. |
SciQ | SciQ-3848 | energy, water, freezing
Title: Where does the energy of the expansion of frozen water come from? As you cool a system, you are removing energy, yet as water transitions to a solid, it expands, exerting sufficient force to rip through metal, for example in residential copper water pipes that freeze. Where does that energy come from? The change from liquid to solid releases some energy as (stronger) bonds are made between the water molecules - latent heat of fusion.
The expansion pushes back the surroundings and work is done at the expense of some of the released energy when the bonds are being made.
The internal energy (potential energy) of the water decreases as heat is abstracted from the water and the water (ice) does work on the surroundings in expanding.
As the bonds are formed the molecules are closer together than their equilibrium separation ie there is “elastic” potential energy stored in bonds and when the containing vessel is ruptured those compressed bonds expand just like a compressed spring releasing energy when it expands.
The following is multiple choice question (with options) to answer.
In winter, water does what, becoming solid and causing hoses to rupture and engine blocks to crack? | [
"crystallizes",
"shrinks",
"fractures",
"freeze"
] | D | In the winter, the temperature often gets well below the freezing point of water. This condition can create problem in car radiators. If the water freezes, water hoses will break, the engine block can crack, and significant damage can be done to the car. |
SciQ | SciQ-3849 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
Unlike archaea and eukaryotes, bacteria have a cell wall made of what? | [
"phospholipids",
"substrates",
"hydrogen",
"peptidoglycan"
] | D | Unlike Archaea and eukaryotes, bacteria have a cell wall made of peptidoglycan, comprised of sugars and amino acids, and many have a polysaccharide capsule (Figure 3.5). The cell wall acts as an extra layer of protection, helps the cell maintain its shape, and prevents dehydration. The capsule enables the cell to attach to surfaces in its environment. Some prokaryotes have flagella, pili, or fimbriae. Flagella are used for locomotion, while most pili are used to exchange genetic material during a type of reproduction called conjugation. |
SciQ | SciQ-3850 | 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 happens to the crust if the moving oceanic crust reaches a deep sea trench? | [
"sinks into mantle",
"it cleaves",
"forms a continent",
"ocean volcano"
] | A | In some places, the oceanic crust comes up to a continent. The moving crust pushes that continent away from the ridge axis as well. If the moving oceanic crust reaches a deep sea trench, the crust sinks into the mantle. The creation and destruction of oceanic crust is the reason that continents move. Seafloor spreading is the mechanism that Wegener was looking for!. |
SciQ | SciQ-3851 | human-genetics, psychiatry
Title: Bipolar disorder genetics My understanding is that bipolar disorder is polygenic.
1) Does one need to have all the genes for bipolar disorder in order to have the disease?
2) Is it possible for a person to have all the genes for bipolar disorder and still not have the disease?
Does one need to have all the genes for bipolar disorder in order to have the disease?
No. In genome-wide association studies (GWAS) of psychiatric conditions, it is a constant finding that the associated variants each influence the probability/risk. The effects of all known variants can then be summed up to a polygenic score (PGS). A person with higher PGS is more likely than someone with a low PGS. But some people with low PGS (i.e. people who don't have "all the genes") still get the condition, it is just not as frequent as people with high PGS.
Another reason why we can say 'no' to this question is through findings of quantitative genetics studies. These estimate the heritability of certain traits. For the answer to be 'yes', the heritability would have to be one ($h^2 = 1$). However, as far as I know, there are no known psychiatric conditions that have heritabilities of one. Some high (e.g. $h^2\approx 0.8$), yes, but not one.
It's also worth mentioning that there is probably no sharp line between having bipolar disorder and not having it. It's a medical diagnosis that is useful but rough. Most likely, all of us have a little "bipolar" in us. I think it's probably most useful to view it as a spectrum.
Is it possible for a person to have all the genes for bipolar disorder and still not have the disease?
This is not known and it may not even be a well-defined question. We don't know all the variants that affect the risk of bipolar disorder (or most other polygenic disorders). So we cannot say for sure.
Some 'omnigenetic' hypotheses propose that all genetic variants have some effect on all traits. Some effects are just smaller and some larger. In this case, the expression 'all the genes for X' may be technically meaningless.
The following is multiple choice question (with options) to answer.
Polygenic traits are controlled by more than one of these? | [
"genomes",
"phenotypes",
"chromosomes",
"genes"
] | D | Some traits are controlled by more than one gene. They are called polygenic traits. Each gene for a polygenic trait may have two or more alleles. The genes may be on the same or different chromosomes. Polygenic traits may have many possible phenotypes. Skin color and adult height are examples of polygenic traits in humans. Think about all the variation in the heights of adults you know. Normal adults may range from less than 5 feet tall to more than 7 feet tall. There are people at every gradation of height in between these extremes. |
SciQ | SciQ-3852 | physiology, cardiology, blood-circulation
Title: What is the quality rate of intrinsic autoregulation in the heart? Autoregulation is the maintenance of constant blood flow to an organ in spite of fluctuations in Blood pressure.
It involves the relaxation of myocardium and contraction.
It is local.
I know that autoregulation is best done in the brain, well in kidneys and badly in skeletal muscle.
I am interested how it is in the heart.
I think it should be at least good.
Brain can be thought more important.
However, I am not sure.
How good is the autoregulation of the blood flow in the heart? My conjecture: Intrinsic regulation is done in the heart the second best, after the brain.
This idea is based on the fact that the brain controls heart's some autonomic functions.
It is an open research question how the autonomic nervous system affects the intrinsic functions of the heart - and the reverse is true too.
To answer this question, we need to understand the autonomic regulation of the heart better i.e. the inner-physiology of the heart's electrical activity.
The following is multiple choice question (with options) to answer.
What system plays a critical role in the regulation of vascular homeostasis? | [
"renal system",
"circulatory system",
"nervous system",
"endocrine system"
] | C | Neural Regulation The nervous system plays a critical role in the regulation of vascular homeostasis. The primary regulatory sites include the cardiovascular centers in the brain that control both cardiac and vascular functions. In addition, more generalized neural responses from the limbic system and the autonomic nervous system are factors. |
SciQ | SciQ-3853 | bond
Title: How can oxygen have three bonds? I was reading an article about a chemical reaction, and I came across the phrase:
The oxygen atom at this point has three bonds and has a net positive charge
How can this happen? Oxygen has 2 missing electrons in the valence shell. Therefore it can only form 2 bonds at the most, if both are sigma bonds.
Does it mean the 3rd bond is not covalent? Can it happen with a hydrogen or an ionic bond? Consider the auto-ionization of water :
$\ce{ 2H_2O->H_3O+ + OH-}$
The first oxygen has three bonds, the second only has one.
You can think of the reaction taking place by a lone pair on the oxygen of one water molecule ripping off the proton only of the hydrogen of another water molecule to form a covalent bond between them using just the lone pair. The electron of the hydrogen is left behind and stays with the oxygen of the other molecule.
If you calculate the formal charges on each oxygen you will see the first one has a positive charge and the second one has a negative. The formal charge is just the valence number of electrons minus the number of bonds minus non-bonding electrons (using the lewis structure) and is a useful book keeping method to think about where the electrons go/are and what are the most stable structures.
Formal Charge Calculation
The following is multiple choice question (with options) to answer.
How many nonpolar bonds does an oxygen molecule have? | [
"2",
"7",
"5",
"3"
] | A | An oxygen molecule has two nonpolar bonds. This is called a double bond. The two oxygen atoms attract equally the four shared electrons. |
SciQ | SciQ-3854 | immunology, immune-system, autoimmune
As for why autoimmunity occurs you also understood the basics, however the devil is in the details: wikipedia does have a much longer list of mechanistically different causes. While its often sufficient to explain immune recognition using 'keys' (T cell receptor / B cell receptor = antibody) and their respective 'locks' (peptides bound to MHC / antigens), the exact process of immune cell activation becomes important in autoimmunity, where cells are wrongly activated. This means that there are many possible points at which the 'security system' of the immune cell maturation can (or rather has to) fail to allow autoimmunity.
As for the cross-reactivity of cells: the difference between the binding of B cells (via antibody/B cell receptor to protein surfaces) and T cells (via T cell receptor to peptide sequences) means that in general T cells are much more likely to show cross reactivity - just because the possibility space of a 10-12aa peptide is much smaller than that of a protein surface (even though the probability is still very low).
Additionally - as stated in the comments to your question - both the immune activation pathway and the issue of cross reactivity, while principally understood, are not 'completely solved'. The immune system is insanely complex just by itself and the addition of interactions with both almost all human proteins AND proteins any kind of pathogen, mean that it will take quite a lot of time until researchers can figure out all the weird quirks caused by the 'wrong' combinations.
The following is multiple choice question (with options) to answer.
What type of disease occurs when the immune system fails to recognize the body's own molecules? | [
"congenital",
"autoimmune",
"gastrointestinal",
"cardiac"
] | B | Autoimmune diseases occur when the immune system fails to recognize the body’s own molecules as “self,” or belonging to the person. Instead, it attacks body cells as though they were dangerous pathogens. There are more than 80 known autoimmune diseases. Recall that regulatory T cells help regulate the immune system. When autoimmune disorders occur, these regulatory T cells fail in their function. This results in damage to various organs and tissues. The type of autoimmune disorder depends on the type of body tissue that is affected. |
SciQ | SciQ-3855 | volcanology, paleontology, volcanic-hazard, archaeology, pyroclastic-flows
Title: Are Pompeii and Herculaneum unique? Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human – have been entombed in the volcanic ash, with the possibility of revealing their forms by producing casts from the voids? Such sites, if they exist, could reveal exciting new knowledge about ancient peoples and animals. Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.
The following is multiple choice question (with options) to answer.
What organism is an important pioneer on cleared rock and soil surfaces, such as volcanic flows and burned forests? | [
"cysts",
"pigment",
"algae",
"lichen"
] | D | |
SciQ | SciQ-3856 | evolution, botany, proteins
tl;dr: the egg contains more proteins than the seed because the chicken that made the egg ate a whole lot of seeds, and all the protein in those seeds ended up concentrated in that one egg.
EDIT: running into this much later I realized I missed a pretty vital half of the question, because there is a difference between fruits and seeds. The difference is the following: nitrogen is precious for plants so they'll try and use it for very important things. Seeds are very important to the plant, so while a seed has less protein than an egg it will still have lots of protein by plant standards. Fruits now, that's another story. Like the sugary nectar, fruits are a bribe for animals, a bit of food offered to them so that they'll spread the plant's seeds. And like with the sugary nectar, the plant has every incentive to pack that bribe full of cheap carbohydrates and as few precious proteins as it can manage.
The following is multiple choice question (with options) to answer.
What hypothetical link between development of herbivores and plant defenses is observed in nature, for instance in seeds that are unsavory to animals? | [
"coevolution",
"interconnection",
"natural selection",
"abjection"
] | A | Animals and Plants: Herbivory Coevolution of flowering plants and insects is a hypothesis that has received much attention and support, especially because both angiosperms and insects diversified at about the same time in the middle Mesozoic. Many authors have attributed the diversity of plants and insects to pollination and herbivory, or consumption of plants by insects and other animals. This is believed to have been as much a driving force as pollination. Coevolution of herbivores and plant defenses is observed in nature. Unlike animals, most plants cannot outrun predators or use mimicry to hide from hungry animals. A sort of arms race exists between plants and herbivores. To “combat” herbivores, some plant seeds—such as acorn and unripened persimmon—are high in alkaloids and therefore unsavory to some animals. Other plants are protected by bark, although some animals developed specialized mouth pieces to tear and chew vegetal material. Spines and thorns (Figure 26.18) deter most animals, except for mammals with thick fur, and some birds have specialized beaks to get past such defenses. |
SciQ | SciQ-3857 | acid-base, ionic-compounds, erratum
Title: Are all ionic compounds salts? According to Wikipedia:
A salt is an ionic compound that can be formed by the neutralization
reaction of an acid and a base.
Are all ionic compounds salts? Are all salts ionic compounds? Interestingly, IUPAC states that a "salt" is "a chemical compound consisting of an assembly of cations and anions". Under this definition, all ionic compounds are salts, and all salts are ionic compounds.
Therefore, something like sodium hydroxide ($\ce{Na+OH-}$, definitely an ionic compound) could actually be correctly called a salt. This clashes with the commonly taught high-school level definition of a salt ("the product of an acid-base reaction"), unless you consider very general definitions of acids and bases such as the Usanovich definition, whereby sodium metal $\ce{Na^0}$ is an electron donor (and therefore a base) and water is an electron acceptor (and therefore an acid).
That said, the high-school definition is too simplistic. It is common for compounds to be an acid, a base and a salt all at the same time; consider for example sodium bicarbonate ($\ce{Na+HCO3-}$). It is made of cations and anions, and therefore is definitely a salt. Furthermore, it can act as both a Brønsted–Lowry acid ($\ce{NaHCO3 + OH- -> H2O + Na+ + CO3^2-}$) and as a Brønsted–Lowry base ($\ce{NaHCO3 + H+ -> Na+ + H2CO3}$). Another amusing example is hydrazinium sulfate, a salt, acid and base, where both the cation and anion are also both acids and bases!
The following is multiple choice question (with options) to answer.
The term salt can refer to essentially any of what compounds? | [
"solvent",
"metallic",
"ionic",
"absorption"
] | C | where the term salt can refer to essentially any ionic compound. An example would be the reaction between hydrochloric acid and potassium hydroxide:. |
SciQ | SciQ-3858 | neuroscience, neuroanatomy
Title: Why is the anterior pituitary not considered part of the diencephalon? According to the wikipedia page on the diencephalon, the posterior pituitary gland is considered part of the diencephalon, but the anterior is not. Is there a reason that these two lobes of the same gland are considered different enough not to be part of the same brain region? Worth going to the wikipedia page on the pituitary:
In all animals, the fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary, which is an extension of the hypothalamus.
The anterior pituitary arises from an invagination of the oral ectoderm (Rathke's pouch). This contrasts with the posterior pituitary, which originates from neuroectoderm.
The posterior lobe develops as an extension of the hypothalamus, from the floor of the third ventricle.
In other words, the different parts of the pituitary are, developmentally, entirely separate. The posterior lobe is actually part of the hypothalamus. The anterior lobe is not even part of the brain.
Lumping them together with one label happened because the anatomists who originally named the thing didn't know much about it, which is not surprising because anatomical names are quite old and understanding of the functions of any parts of the brain is quite new. Old names stick.
The following is multiple choice question (with options) to answer.
Where is the hypothalamus–pituitary complex located in the body? | [
"diencephalon of the brain",
"stem of the brain",
"tribulus of the brain",
"subthalamic of the brain"
] | A | 17.3 The Pituitary Gland and Hypothalamus The hypothalamus–pituitary complex is located in the diencephalon of the brain. The hypothalamus and the pituitary gland are connected by a structure called the infundibulum, which contains vasculature and nerve axons. The pituitary gland is divided into two distinct structures with different embryonic origins. The posterior lobe houses the axon terminals of hypothalamic neurons. It stores and releases into the bloodstream two hypothalamic hormones: oxytocin and antidiuretic hormone (ADH). The anterior lobe is connected to the hypothalamus by vasculature in the infundibulum and produces and secretes six hormones. Their secretion is regulated, however, by releasing and inhibiting hormones from the hypothalamus. The six anterior pituitary hormones are: growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL). |
SciQ | SciQ-3859 | species-identification, zoology, entomology
Title: Very small, light and dark "insects" - Italy - Infestation, healthy problems? - Insect identification I'm currently in a town near Savona, on the coast in north-west Italy.
We had a problem with pigeons, that create their nests in the space between the roof and the ceiling.
Now, from the tube of the kitchen hood, that passes through this space, fell down these little insects. I'm a bit concerned it might be ticks, or something that could possibly transmit something bad. We have hundreds of them.
What's the best solution to make them go away? Also, should we leave the house during they permanence? I'm sorry for the bad quality pictures but they are very very small (probably between 0,5 and 1 mm) and very fast, so it's difficult to take good pictures.
Thankful for your help.
Dropbox link with more images and better quality I suspect these will be bird mites. These are a range of species from two genera (Ornithonyssus and Dermanyssus) that mainly infest birds, but can also cause infestations in humans, causing a condition known as Gamasoidosis. I don't know much about them, but a bit of googling tells me they are commonly seen when a colony of birds is removed from a building and they no longer have a host to live on, so spread out trying to find new hosts.
Adults are in the range of 1/2 to 1 mm long, so quite small. They cause non-specific itchy papules in humans, which are where they bite to suck blood. I think you should be able to kill them with common insecticides.
Getting professional pest control advice is a good idea as it seems infestations can be hard to get rid of because they can live off human and pet blood.
The following is multiple choice question (with options) to answer.
Where is the guinea worm a serious problem? | [
"africa",
"russia",
"florida",
"ukraine"
] | A | Guinea worm is a serious problem in parts of Africa that is being eradicated. Learn what is being done to decrease the number of people suffering from this parasite at the video below:. |
SciQ | SciQ-3860 | inorganic-chemistry, physical-chemistry, ionic-compounds, reactivity
Title: Why does calcium oxide react with sulfur dioxide?
Which of the following compounds reacts with calcium oxide, $\ce{CaO}$?
(a) $\ce{K2O}$
(b) $\ce{Na2O}$
(c) $\ce{SO2}$
(d) $\ce{MgO}$
I thought that since sodium is higher in the reactivity series than Ca, then it would be B. However, the answer is C, and I'm not quite sure why. Can anyone enlighten me? If a reaction takes place there should be a reasonable chemical equation.
Calcium oxide and sulfur dioxide may react to give calcium sulfite:
$$\ce{CaO + SO2 -> CaSO3}$$
On the other hand alkali metal oxides and alkaline earth metal oxides do not form mixed oxides.
The reactivity series gives us information about the feasibility of redox reactions. Since no redox reactions can occur here, the reduction potentials are not relevant.
The following is multiple choice question (with options) to answer.
The reaction of calcium oxide with carbon dioxide forms what? | [
"carbon monoxide",
"nitrogen",
"calcium carbonate",
"nitrogen carbonate"
] | C | The way in which a reaction is written influences the value of the enthalpy change for the reaction. Many reactions are reversible, meaning that the product(s) of the reaction are capable of combining and reforming the reactant(s). If a reaction is written in the reverse direction, the sign of the changes. For example, we can write an equation for the reaction of calcium oxide with carbon dioxide to form calcium carbonate. |
SciQ | SciQ-3861 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
Cilia or flagella structures give protists what ability? | [
"reproduction",
"eating",
"breathing",
"movement"
] | D | An animal-like protist, or a protozoa. These protists have the ability to move, usually with some sort of cilia or flagella, and must obtain their energy from other sources. But obviously, they are much simpler than animals. |
SciQ | SciQ-3862 | cancer
Title: do tumour cells begin with abnormal characteristics? At what point in the cell cycle do cells start to become tumorous? Do they have abnormal characteristics to begin with; if so what are they? Cancer cells don't start to become cancerous at a specific stage of the cell cycle; you will find that while uncontrolled proliferation is a hallmark of cancer, different cancers acquire alterations in different phases of the cell cycle. BRCA-deficient cancers for example have a compromised G2-M checkpoint [1], while Rb deficient cancers have a compromised G1-S [2] checkpoint in the cell cycle.
The cell cycle is simply a property of proliferating cells and the same broad phases of the cell cycle are universal to both normal and malignant cells.
As for when abnormally growing cells actually become a cancer - this has nothing to do with phases of the cell cycle, and everything to do with the ability to break through the basement membrane of the original site (indicating the potential to be invasive/spread), because the ability to invade is a hallmark of cancer [3]
References
[1] http://cancerres.aacrjournals.org/content/67/13/6286
[2] https://www.ncbi.nlm.nih.gov/pubmed/16936740
[3] https://www.ncbi.nlm.nih.gov/pubmed/21376230
The following is multiple choice question (with options) to answer.
What is characterized by uncontrolled cell division of abnormal cells? | [
"concussions",
"hepatitis",
"radiation",
"cancer"
] | D | cell depletion, organ system failure, and impaired tissue injury responses. Telomerase reactivation in these mice caused extension of telomeres, reduced DNA damage, reversed neurodegeneration, and improved the function of the testes, spleen, and intestines. Thus, telomere reactivation may have potential for treating age-related diseases in humans. Cancer is characterized by uncontrolled cell division of abnormal cells. The cells accumulate mutations, proliferate uncontrollably, and can migrate to different parts of the body through a process called metastasis. Scientists have observed that cancerous cells have considerably shortened telomeres and that telomerase is active in these cells. Interestingly, only after the telomeres were shortened in the cancer cells did the telomerase become active. If the action of telomerase in these cells can be inhibited by drugs during cancer therapy, then the cancerous cells could potentially be stopped from further division. |
SciQ | SciQ-3863 | human-biology, evolution
Humans are off the charts in the amount of resources we invest in our children - our lives are 1/4 to 1/3 over before we sometimes leave our parents household (in some societies of course they never leave the house, but step into an extended family). This may be one of the reasons we are so successful as a species - we live in practically every place we possibly could and have no danger of competition from any other living thing excepting ourselves.
The grandmother effect is essentially the idea that if women, who are more attached to the offspring in more cases than fathers, continue to live and help support the grandchildren and make them more successful, then this will allow post menopausal women to have a longer lifespan (which they do).
The evolutionary biologist Sara Hrdy, emeritus UC Davis, has written quite a bit about the nuances of the evolution of the role of motherhood - reading some of her articles or books might give you a deeper sense of how profoundly filial love has shaped human beings.
--- more answer this stuff may or may not be worth reading depending on how broadly you want to understand this question...
Its important to say that many of the expansions of human average human lifespan have not been genetic. Its commonly cited that sewer systems, clean water, antibiotics and plentiful food are the three most important factors in human lifespan - and before modern developed world nations, the average lifespan of human beings was somewhere in the 30s. And there are significant lifespan differences in regions where these factors and others (education of women, access to prenatal and early care etc) are available.
Studies continue to be published that examine environmental and lifestyle factors compared to genetics and it seems that environment and lifestyle can make an astounding difference.
But genetics undoubtedly has a role to play here too. There are probably some individual humans and animals which have evolved to live longer. This has been found to be genetically related in some humans by demographics and family lines.
The following is multiple choice question (with options) to answer.
Our global ecological footprint depends on resource use per person and what population factor? | [
"population sample",
"population fluctuation",
"population density",
"population decrease"
] | C | |
SciQ | SciQ-3864 | waves, acoustics, diffraction, wave-particle-duality
Title: Diffraction of Sound Waves We know that Sound waves are Longitudinal waves. It mean that there is pressure difference created when medium particles move. But while diffraction of sound waves "How will the medium particles move". Will they get any sideward push. So that sound diffract sidewards.
Is the reason for this question is same for light diffraction... If photon theory worked out then it might be same. What if wave nature worked out in light diffraction?
When wave length increases then diffraction effects will be more. How are they related? It's ultimately the same reason why light refracts, Huygens's Principle.
You're thinking of the sound as "a wave", in this particular case you're looking at it where its roughly linear. So then, why does this linear thing suddenly move sideways when it goes through a hole?
Think about it differently; according to Huygens a wave front is the mathematical addition of an infinity of spherical waves. You see a linear wave, but that's because you're macroscopic. At the microscopic level that's not what's happening, at that level its moving in all directions all the time.
So wait, if the microscopic "things" are moving spherically, then why did you have a linear wavefront to start with? Because over an extended front, every bit of the wave that's going, say, right, has another bit somewhere else going left. When you sum it all up, all the "sideways bits" sum to zero, and the only leftover terms are the ones from the original disturbance, moving outward.
So what happens at the slit? Well consider the spot right on the left edge of the opening... the left side of it is moving left and the right side is moving right (its spherical). Now before it got to the slit there was another spot to it's left that was doing the same thing. So the left moving bit of spot A was being cancelled out by the right moving bit of spot B. Ahhh, but B just hit the wall, literally. So no no one is stopping the left-moving side of A.
Presto, at our macroscopic level, it looks like it started moving left. But that's not "really" what happened.
The following is multiple choice question (with options) to answer.
What do all sound waves begin with? | [
"enclosing matter",
"oscillating matter",
"vibrating matter",
"talking matter"
] | C | All sound waves begin with vibrating matter. The vibrations generate longitudinal waves that travel through matter in all directions. |
SciQ | SciQ-3865 | 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.
Animal starch, called glycogen, is stored in the liver and where else? | [
"kidneys",
"hands",
"nerves",
"muscles"
] | D | Note the Pattern Because carbohydrates have a carbonyl functional group and several hydroxyl groups, they can undergo a variety of reactions. Two familiar polysaccharides are starch and cellulose, which both hydrolyze to produce thousands of glucose units. They differ only in the connection between glucose units and the amount of branching in the molecule (Figure 24.22 "The Polysaccharides Starch and Cellulose"). Starches can be coiled or branched and are hydrolyzed by the enzymes in our saliva and pancreatic juices. Animal starch, called glycogen, is stored in the liver and muscles. It consists of branched glucose units linked by bonds Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-3866 | newtonian-mechanics, newtonian-gravity, angular-momentum, conservation-laws, orbital-motion
My textbook describes Kepler's second law as follows:
$$
\int_{t_1}^{t^2}rv_\phi\,\mathrm dt=C\int_{t_1}^{t_2}\mathrm dt=C(t_2-t_1),
$$
where $C$ is a constant.
The following is multiple choice question (with options) to answer.
Kepler's laws relate to the motion of what? | [
"planets",
"the sun",
"continents",
"oceans"
] | A | The system is isolated from other masses. This allows us to neglect any small effects due to outside masses. The conditions are satisfied, to good approximation, by Earth’s satellites (including the Moon), by objects orbiting the Sun, and by the satellites of other planets. Historically, planets were studied first, and there is a classical set of three laws, called Kepler’s laws of planetary motion, that describe the orbits of all bodies satisfying the two previous conditions (not just planets in our solar system). These descriptive laws are named for the German astronomer Johannes Kepler (1571–1630), who devised them after careful study (over some 20 years) of a large amount of meticulously recorded observations of planetary motion done by Tycho Brahe (1546–1601). Such careful collection and detailed recording of methods and data are hallmarks of good science. Data constitute the evidence from which new interpretations and meanings can be constructed. |
SciQ | SciQ-3867 | electrochemistry, nanotechnology, colloids
Title: Generating colloids / nano-particles from palladium and platinum wire I know I can generate colloidal silver from the following link
generate colloidal silver
I now have 2 palladium and 2 platinum wires and would like to make one colloidal solution of palladium and one colloidal solution of platinum both in distilled water. I watched a video on doing this making platinum nanoparticles link but no specifics were given on how it was made, did they use AC / DC voltage, what was the amperage used, and can it be made in distilled water and if so how?
Anyone have suggestions or steps I should follow? A reliable method to obtain metallic nanoparticles in general is to reduce a metallic ion in presence of a capping agent. For a example, a traditional method to obtain gold nanoparticles (AuNPs) is to reduce a gold salt in presence of dodecanothiol.
For example, here is a method to obtain Pd nanoparticles by thermal decomposition, still the precursor is a Pd complex and the method requires a capping agent. (TOP stands for trioctylphosphine)
The following is multiple choice question (with options) to answer.
Colloids are used industrially as what? | [
"organisms",
"impurities",
"catalysts",
"solutions"
] | C | Suspensions and colloids are two common types of mixtures whose properties are in many ways intermediate between those of true solutions and heterogeneous mixtures. Asuspension is a heterogeneous mixture of particles with diameters of about 1 µm (1000 nm) that are distributed throughout a second phase. Common suspensions include paint, blood, and hot chocolate, which are solid particles in a liquid, and aerosol sprays, which are liquid particles in a gas. If the suspension is allowed to stand, the two phases will separate, which is why paints must be thoroughly stirred or shaken before use. A colloid is also a heterogeneous mixture, but the particles of a colloid are typically smaller than those of a suspension, generally in the range of 2 to about 500 nm in diameter. Colloids include fog and clouds (liquid particles in a gas), milk (solid particles in a liquid), and butter (solid particles in a solid). Other colloids are used industrially as catalysts. Unlike in a suspension, the particles in a colloid do not separate into two phases on standing. The only combination of substances that cannot produce a suspension or a colloid is a mixture of two gases because their particles are so small that they always form true solutions. The properties of suspensions, colloids, and solutions are summarized in Table 13.9 "Properties of Liquid Solutions, Colloids, and Suspensions". |
SciQ | SciQ-3868 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
What is defined as the temperature plus precipitation of an area over a long period of time? | [
"weather",
"climate",
"conditions",
"environment"
] | B | Climate is the temperature plus precipitation of an area. Not just today, but over a long period of time. Climate affects chemical weathering. Chemical weathering increases as:. |
SciQ | SciQ-3869 | cell-biology, mitochondria
Title: How is the number of mitochondria in a cell regulated? How does the cell regulate the number of mitochondria in a cell? What happens when there are too many or too few? The concept you refer is recognized as mitochondrial biogenesis and it is regulated by AMPK which senses the cellular energy demand. If you have few mitochondria in the cell, the electron transport chain works suboptminally generating less ATP. When the AMP/ATP ratio is high (low ATP) AMPK is activated, and turns on the catabolic pathways required to produce more ATP, included mitochondrial biogenesis.
The following is multiple choice question (with options) to answer.
What manages the material and energy resources of the cell? | [
"nucleus",
"cell wall",
"metabolism",
"respiration"
] | C | |
SciQ | SciQ-3870 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
What is the midpiece of sperm packed with? | [
"mitochondria",
"protein",
"urine",
"glucose"
] | A | The midpiece of the sperm is packed with mitochondria. Mitochondria are organelles in cells that produce energy. Sperm use the energy in the midpiece to move. |
SciQ | SciQ-3871 | 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.
Dry soils are relatively unproductive because plants need a sufficient quantity of liquid water to carry out what process? | [
"shrinkage",
"flowering",
"photosynthesis",
"contraction"
] | C | |
SciQ | SciQ-3872 | food, nutrition
Supplements aren't intended to be a food substitute because they can't replicate all of the nutrients and benefits of whole foods, such as fruits and vegetables.
and there are three main differences:
Greater nutrition. Whole foods are complex, containing a variety of
the micronutrients your body needs — not just one. An orange, for
example, provides vitamin C plus some beta carotene, calcium and
other nutrients. It's likely these compounds work together to produce
their beneficial effect.
Essential fiber. Whole foods, such as whole grains, fruits,
vegetables and legumes, provide dietary fiber. Most high-fiber foods
are also packed with other essential nutrients. Fiber, as part of a
healthy diet, can help prevent certain diseases, such as type 2
diabetes and heart disease, and it can also help manage constipation.
Protective substances. Whole foods contain other substances important
for good health. Fruits and vegetables, for example, contain
naturally occurring substances called phytochemicals, which may help
protect you against cancer, heart disease, diabetes and high blood
pressure. Many are also good sources of antioxidants — substances
that slow down oxidation, a natural process that leads to cell and
tissue damage.
So you could live off of some meal replacement shake for the rest of your life but should you? Probably not.
The following is multiple choice question (with options) to answer.
The vitamins and minerals contained in all of the food we consume are important for all of our organ systems. however, there are certain nutrients that affect this? | [
"mental health",
"abnormal health",
"bone health",
"chain health"
] | C | Nutrition and Bone Tissue The vitamins and minerals contained in all of the food we consume are important for all of our organ systems. However, there are certain nutrients that affect bone health. |
SciQ | SciQ-3873 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What type of plants supplement their mineral nutrition by digesting animals? | [
"herbivorous",
"annuals",
"perennials",
"carnivorous"
] | D | |
SciQ | SciQ-3874 | cell-biology, mitochondria, mitosis
Title: Are cells guaranteed to get at least one mitochondrion when they divide? If mitochondria exist at random within a cell, isn't there a possibility that cell division will result in a daughter cell with no mitochondria? If not, what is the process for guaranteeing at least one is present in each daughter cell? If so, what happens to that cell?
Isn't there a possibility that cell division will result in a daughter
cell with no mitochondria?
Yes, there is always the possibility. However, there must be a strong negative selection pressure against eukaryotic life that cannot achieve the proper partitioning of mitochondria, so you can imagine that there are mechanisms in place to prevent this case.
Mitochondria are both passively and actively partitioned to daughter cells. This is understood to occur through the cytoskeleton and with the control of mitochondrial fusion and fission at key stages of the cell cycle, prior to mitosis and cytokinesis!
Here is a great review from several years ago that addresses your question well.
The following is multiple choice question (with options) to answer.
Daughter cells divide by what? | [
"electrolysis",
"nucleus",
"mitosis",
"meiosis"
] | D | The daughter cells then start to divide by meiosis . But they only go through the first of the two cell divisions of meiosis at that time. They go through the second stage of cell division after the female goes through puberty. |
SciQ | SciQ-3875 | molecular-biology, botany, perception, receptor, light
Title: Receptors for red and far-red light in plants: Shade avoidance Franklin (2009) describes how plants use the ratio of the red wavelength (660-670nm) over the far-red wavelength (725-735nm) (R:FR) in order to avoid shading.
My question is: which receptor is stimulated by the red and which receptor is stimulated by the far-red?
In his paragraph on Phytochromes (3rd page, right column), K. Franklin seems to say that PhyB is responsible for measuring this ratio but I am not sure. As far as I know there are 5 receptors for far-red and red light which are the phytochroms(phyA-phyE) Its all about the ratio between red and far-red light.
Each phytochrom has an inactive(PR) and an active(PFr) conformation. phyA is the only phytochrom which is activated by far-red light, so its active state is PR. (Only if the ratio between red and far-red light is low.) The other phytochroms, are activated by red light (high ratio between red and far-red).
An active phytochrom blocks the COP1/SPA complex. This complex is a E3 ubiquitin ligase which ubiquinates transcription factors for the light answer like HY5 or HFR1.
Example:
Under normal light conditions, phyB-phyE is active. They block the COP1/SPA complex so the transcription factors for the light answer are not getting ubiquinated. The plant can get a light phenotyp.
In the case that a plant grows under another plant, it gets less red light because the higher growing plant uses it for its photosynthesis. phyB-phyE become inactive. COP1/SPA can ubiquinate the transcriptions factors. The plant gets an low light phenotyp by trying to grow out of the shadow.
The function of phyA is to produce a light phenotyp if there is a lot of far-red light but almost no red light. Than it is getting activated and blocks the COP1/SPA complex. Under red light phyA is not only inactivated it also gets degraded.
The following is multiple choice question (with options) to answer.
Phytochromes regulate many plant responses to what? | [
"heat",
"gravity",
"light",
"oxygen"
] | C | |
SciQ | SciQ-3876 | organic-chemistry, molecules, carbohydrates
Title: When oxygen is connected only to carbon, are then the oxygen and carbon connected with a double bond? My teacher showed us three molecules: a carbohydrate molecule, a protein molecule, and a lauric acid molecule. I noticed that, when an oxygen atom is connected to one carbon atom and isn't connected to any other atom, then the oxygen and carbon atoms are connected with a double bond. Is my hypothesis correct, and has anyone ever found it before? Over 150 years ago August Kekulé had a dream about how atoms might form molecules. You might find it interesting to read about it.
Chemistry is largely about valence, the number of connections that each atom is able to make with other atoms.
In the cases you are talking about, with co-valent bonds, you can imagine each carbon atom as having 4 arms reaching out, each oxygen having two arms, and each hydrogen having 1 arm.
If an oxygen atom is connected to only one other atom, then that connection must use both arms, holding hands with 2 of the carbon atom's arms (just as you noticed), forming a double bond.
The carbon's other two arms could be connected to another oxygen atom, forming CO2 (carbon dioxide), or to 2 Hydrogen atoms, forming CH2O (formaldehyde).
Or it could double bond to another carbon atom, which in turn has two more arms to connect to something else, such as C2H5OH (drinking alcohol).
Molecules based on carbon are so common and potentially so complicated, that there is a whole field (organic chemistry) based on it.
If you are at all interested in chemistry, the concept of valence will be essential to your understanding.
The following is multiple choice question (with options) to answer.
Carbon dioxide molecules consist of a central carbon atom bonded to how many oxygen atoms? | [
"two",
"three",
"four",
"one"
] | A | Carbon dioxide molecules consist of a central carbon atom bonded to 2 oxygen atoms. |
SciQ | SciQ-3877 | Its cdf: $F(x) = \left\{ \begin{array}{cl} 1 - \Big(\frac{x_m}{x}\Big)^{\alpha} & if~~x \geq x_m \\ 0 & if~~x < x_m \end{array} \right.$
alpha=2;xm=1;
curve(ppareto(x,alpha,xm),xlim=c(1,10),ylim=c(0,2),lwd=2,
ylab='pareto(alpha=2,xm)',main='Pareto CDFs')
## Warning in log1p(-(scale/q)^shape): NaNs produced
curve(ppareto(x,alpha, 2),col='red',lwd=2,add=T)
## Warning in log1p(-(scale/q)^shape): NaNs produced
curve(ppareto(x,alpha, 4),col='blue',lwd=2,add=T)
## Warning in log1p(-(scale/q)^shape): NaNs produced
legend(par('usr')[1], par('usr')[4], xjust=0,
c('xm=1', 'xm=2', 'xm=4'),
lwd=c(2,2,2), # line width
lty=c(1,1,1), # line trace
col=c('black', 'red', 'blue'))
This distribution was originally used to describe the allocation of wealth among individuals since it seemed to show rather well the way that a larger portion of the wealth of any society is owned by a smaller percentage of the people in that society. This distribution is not limited to describing wealth or income, but to many situations in which an equilibrium is found in the distribution of the “small” to the “large”. E.g.s: sizes of human settlements, sizes of meteorites, areas brunt in forest fires, casualty losses in certain businesses.
There’s a relation with the exponential distribution:
The following is multiple choice question (with options) to answer.
Survivorship curves show the distribution of individuals in a population according to what metric? | [
"age",
"birth rate",
"height",
"weight"
] | A | Figure 19.4 Survivorship curves show the distribution of individuals in a population according to age. Humans and most mammals have a Type I survivorship curve, because death primarily occurs in the older years. Birds have a Type II survivorship curve, as death at any age is equally probable. Trees have a Type III survivorship curve because very few survive the younger years, but after a certain age, individuals are much more likely to survive. |
SciQ | SciQ-3878 | bond
Title: Types of bonds in a molecule For example in dinitrogen pentoxide, $\ce{N2O5}$, covalent as well as coordinate bonds (type of covalent bonds) are present, but it appears that it contains only covalent bond.
What is a proper method to find out which type of bonds are present in a molecule? Electrovalent bonds are easiest to identify. If a compound is made up of a metal and non-metal/non-metallic radical (like carbonate), then, 99.99% times, it contains electovalent bond. If a compound is made up of 2 or more non-metals/non-metallic radicals, then it contains covalent bond. Coordinate covalent bonds appear mostly with compounds containing Hydrogen element. To identify the coordinate covalent bonds, you can draw the branched structural formula of the compound and see if the shared pair of electrons are coming from the same molecule.
The following is multiple choice question (with options) to answer.
Electrons are not shared equally between the two atoms in which type of covalent bonds? | [
"narrow",
"solar",
"wide",
"polar"
] | D | In polar covalent bonds, electrons are not shared equally between the two atoms, so one atom is slightly negative in charge and one is slightly positive in charge. In nonpolar covalent bonds, electrons are shared equally so the atoms remain neutral in charge. |
SciQ | SciQ-3879 | botany, species-identification, entomology
Title: What is this tiny thing on the branch I noticed a tiny spot with weird shape on the shoot of a plant (Variegata), and there are many others on other branches. I wonder what is it, this is a cropped picture of it, Thank you!
This is a female of yet another scale insect (Coccoidea). We have discussed one recently.
I guess we can identify this one rather precisely as Ceroplastes sinensis or its close relative. Species of this group are of South American origin, but Ceroplastes sinensis has today an extremely broad distribution. So, if you found this plant ("Variegata" is a specific epithet, by the way: it would be of some help if you provided the generic name as well) in Europe or Asia it's likely sinensis itself.
The following is multiple choice question (with options) to answer.
What is above each leaf scar? | [
"an axillary bud",
"chambered pitch",
"lenticel",
"stipule scar"
] | A | |
SciQ | SciQ-3880 | circulatory-system, lymphatic-system, veins
Title: How does most of lymph get back into the blood stream? (I don't mean the lymphatic system) I once read that it was because of osmotic pressure that it returns to the blood stream, by entering the venules. But why? If lymph originated as plasma how come that the solute concentration is higher in the venule? Doesn't plasma contain solutes such as salts, nutrients, oxygen, etc. ? Technically 'lymph' is used to refer to the fluid found within the lymphatic system. If it's not in the lymphatic system, it is not lymph fluid. Thus, your question is really asking about interstitial fluid or the plasma that was filtered out of blood capillaries.
The answer to your question is based on the Starling equation. Normally fluid leaves a capillary due to a net pressure that favors the interstitium. This net pressure is based on the hydrostatic pressure within the capillary being greater than the interstitial pressure of the surrounding tissues, and the oncotic pressure of the capillary (that draws fluid in) being weaker than the hydrostatic pressure of the capillary (that pushes fluid out). At the venule end of this system, the capillary oncotic pressure is stronger than the capillary hydrostatic pressure, drawing fluid back into the circulatory system.
Remember that albumin is the most important component which establishes the oncotic pressure within a vessel, and that this protein is normally NOT released out of a vessel during filtration. Thus, it passes from the capillary into its corresponding venule directly.
The following is multiple choice question (with options) to answer.
Ultimately, the fluid that is lost from the blood vessels is returned through what system? | [
"lymphatic",
"venous",
"symptomatic",
"urinary"
] | A | None of your blood vessels are leaking this badly, or you'd be in the hospital! But your blood vessels do leak a little bit. Water and solutes pass out of the blood vessels and help form the fluid that bathes your body's tissues. Ultimately the fluid that is lost from the blood vessels is returned through the lymphatic system. |
SciQ | SciQ-3881 | thermodynamics, energy, earth, thermal-radiation
@Benjohn has given you the correct answer. Here is my take.
The ultimate heat provider of the earth ( except a small percentage of heat from the magma at the center of the earth) is the sun. It pours down at the surface about 1.2 kilowatts of energy per meter square ( which btw is directly used by solar panels). The same energy falls on the surface of the moon whose surface burns up during its daytime and freezes by black body radiation at night.
The earth is fortunate to have a gas atmosphere which mitigates the extremes of the possible temperatures that the ground would reach otherwise. An example of mitigation is what happens at the sea floor. Most of the energy is picked up by the water and the floor is kept at a steady temperature with small changes day and night in the first meters from the surface, depending on the season, radiating away with the black body radiation, but the body of water has such large heat capacity that variations are small.
The gas atmosphere is a more temperamental "blanket", its heat capacity depends on several gases , called green house gases from the bad impression that agricultural green houses work that way ( they do not, they work by inhibiting heat exchange by convection but that is another story, on which there is no controversy).
The main green house gas is water , H2O. It is worth contemplating this figure :
Solar irradiance spectrum above atmosphere and at surface. Extreme UV and X-rays are produced (at left of wavelength range shown) but comprise very small amounts of the Sun's total output power.
We see that H2O has the most absorption spectrum for infrared wavelengths, (which are the wavelengths of heat )and then comes CO2. Green house gases absorb both incoming and reflected from the surface of the earth infrared, and as most of the reflected wavelengths are in the infrared they act as a slowing down of the black body radiation that would finally leave the earth. As a blanket keeps a person warmer green house gases by playing ball with infrared radiation ( the wavelengths where heat is really transferred) keep the surface of the earth into a reasonable temperature for life, lucky us.
The following is multiple choice question (with options) to answer.
What type energy sources emit fewer or no greenhouse gases? | [
"fossil",
"animal",
"renewable",
"gas"
] | C | New technologies can be developed. Renewable energy sources emit fewer or no greenhouse gases. These sources are discussed in the chapter Natural Resources . |
SciQ | SciQ-3882 | astrophysics, stars
Title: How is the CNO cycle able to occur in main sequence stars if they only fuse hydrogen into helium? From what I understand, main sequence stars only fuse Hydrogen into Helium, and this is mainly due to the proton-proton chain or the CNO cycle.
However, the CNO cycle requires a carbon catalyst. If these main sequence stars only fuse hydrogen into helium, how can the CNO cycle even take place if there isn't any carbon present? You are correct in that CNO needs a catalyst. Fortunately we can find the carbon from outside sources.
Since a dying star will end up containing large amounts of heavy elements like carbon, beryllium etc. Once it dies, those elements are mixed into the next generation of stars, altering their metallicity.
Current stars are part of the second or third generation, allowing them to contain small amounts of heavier elements like carbon. This can then be used by stars that are massive enough for the CNO cycle.
The following is multiple choice question (with options) to answer.
Stars spend most of their lives on the main sequence, fusing hydrogen into what? | [
"neon",
"carbon",
"nitrogen",
"helium"
] | D | Stars spend most of their lives on the main sequence, fusing hydrogen into helium. |
SciQ | SciQ-3883 | density, air, buoyancy
Title: Feeling of coldness in heights We know that due to buoyancy the cold air sinks and warm air floats above it due to it being less dense than cold air. Then why do we feel cold as we go to greater heights/hill stations and feel hot when we are in the normal surface of earth? This is because the air pressure changes significantly with height, and compression or expansion of a gas causes it to warm or cool. In a convective atmosphere, temperature differences cause air to rise in some places and descend in others. When it rises, it expands, and that causes it to cool. When air descends, it is compressed, and that causes it to warm.
(The compressive warming/cooling of gases is also why a bicycle tyre air pump gets hot when you use it, and how a refrigerator works.)
This warming and cooling effect stabilises the atmosphere against heat rising. If the rate of temperature change with height is less than a particular value called the adiabatic lapse rate (ALR), then the atmosphere is stable and warm air won't rise. ('Adiabatic' means that we assume there is no heat gained or lost from an air packet by radiation or conduction.) If the gradient exceeds the adiabatic lapse rate, then convection suddenly starts up again, the heat rises and reduces the gradient back down until, usually in a matter of minutes to a few hours, it once again equals the adiabatic lapse rate.
The adiabatic lapse rate in dry air is about $9.8$ K/km, so for every $1$ km you rise, the temperature drops $1$ K (= $1^\circ$C). However, in the presence of water vapour, there is an additional heating and cooling effect from the condensation or evaporation of water droplets (latent heat of condensation). This reduces the lapse rate down to around $6.5$ K/km, called the moist adiabatic lapse rate (MALR). This is the value the International Standard Atmosphere assumes for aviation purposes, and is generally a pretty accurate approximation, but there are variations from it depending on humidity and weather conditions. (In particular, at night or in the polar winters you can get temperature inversions when surface heating stops and cold air pools near the surface.)
The following is multiple choice question (with options) to answer.
What is a measure of how hot or cold the air is? | [
"relativity",
"precipitation",
"variation",
"temperature"
] | D | |
SciQ | SciQ-3884 | 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.
Where are more of an insect's internal organs kept? | [
"the chest cavity",
"the head",
"the abdomen",
"the thorax"
] | C | An insect’s abdomen contains most of the internal organs. Like other arthropods, insects have a complete digestive system. They also have an open circulatory system and central nervous system. Like other terrestrial arthropods, they have trachea for breathing air and Malphigian tubules for excretion. |
SciQ | SciQ-3885 | energy, particle-physics, collision, higgs
Title: How's the energy of particle collisions calculated? Physicists often refer to the energy of collisions between different particles. My question is: how is that energy calculated? Is that kinetic energy?
Also, related to this question, I know that the aim is to have higher and higher energy collisions (e.g to test for Higgs Boson). My understanding is that to have higher energy you can either accelerate them more, or use particles with higher mass. Is this correct? I think your question is divided in two parts.
When talking about energy, in the field of HEP or accelerator physics we can talk about
total energy
kinetic energy
momentum
The following is multiple choice question (with options) to answer.
What is the measure of kinetic energy of the particles in matter? | [
"friction",
"temperature",
"precipitation",
"energy"
] | B | Temperature is a measure of the average kinetic energy of the particles in matter. In everyday usage, temperature indicates a measure of how hot or cold an object is. Temperature is an important parameter in chemistry. When a substance changes from solid to liquid, it is because there was an increase in the temperature of the material. Chemical reactions usually proceed faster if the temperature is increased. Many unstable materials (such as enzymes) will be viable longer at lower temperatures. |
SciQ | SciQ-3886 | muscles, lungs, human-physiology
Title: Why is there smooth muscle in our bronchioles? Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just remain open? There are at least two things to consider.
First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good enough source of that)
Secondly, you are incorrect in assuming that normal state is "dilated". Dilation of branchioles is sympathetic ("fight-and-fly") response of the nervous system to something like danger, that requires short-term boost in energy production. That is, by default, your airflow is limited. Probably, to limit amount of energy you effectively burn via oxygenation. But most importantly, you leave yourself a reserve in terms of oxygen supply for critical moments.
Some more information you might find here.
The following is multiple choice question (with options) to answer.
What is the name for the tiny air sacs at the end of bronchioles? | [
"gills",
"alveoli",
"ganglion",
"vacuoles"
] | B | Finally, air passes from the bronchi into smaller passages called bronchioles. The bronchioles end in tiny air sacs called alveoli. |
SciQ | SciQ-3887 | electromagnetism, energy, poynting-vector
Title: Veritasium Electricity videos: where does the majority of energy really flow? After watching Veritasium second video on electricity (references at the end), I have some doubts about where the majority of the energy flow actually happens. The reference experiment is the simple circuit made of a battery, switch and load (resistor).
Feynman Lectures: In Volume II, 27-4, Feynman remarks that:
we must say that we do not know for certain what is the actual location in space of the electromagnetic field energy
The following is multiple choice question (with options) to answer.
What is the source of most of the energy used? | [
"fossil fuels",
"the sun",
"the Moon",
"the Earth"
] | B | The Sun produces far more energy than humans can use. The Sun is also the source of most of the energy we use. Fossil fuels and wind energy, for example, originate with the Sun. So why don't we get all our energy from the Sun? For one reason, it's not always practical. |
SciQ | SciQ-3888 | biochemistry
Now we can go on to explain the action potential in the neuron, which is not something I originally wanted to go into, but since the original question has been edited I feel that I have to address this now. Even though the original question now makes no reference to the action potential, it is describing exactly those events that occur during an action potential.
The inside and the outside of the neuron is separated by a cell membrane, which is selectively permeable to ions such as $\ce{Na+}$, $\ce{K+}$, $\ce{Ca^2+}$, and $\ce{Cl-}$. Of these four, sodium and potassium ions are the most important as they are directly involved in depolarisation and repolarisation when an action potential is generated.
The distribution of ions is not symmetrical across the membrane. When at rest, the extracellular concentration of $\ce{Na+}$ is much higher than the intracellular concentration of $\ce{Na+}$; the converse is true for $\ce{K+}$. Due to the membrane having different permeabilities to $\ce{Na+}$ and $\ce{K+}$ (for details of this, one can consult a neuroscience text), the resting membrane potential is -70 mV. Conventionally, the membrane potential is described as the intracellular potential with respect to the potential of the extracellular potential; this means that the inside of the cell is more negative.
Neurons react to certain stimuli by having $\ce{Na+}$ enter the cell, via various means which are not important to the current discussion. Since positively charged ions are entering the cell, this causes the membrane potential to rise. Once the membrane potential has risen to roughly -55 mV, voltage-gated $\ce{Na+}$ channels open, making the membrane permeable to $\ce{Na+}$.
At this stage, we have to consider the two factors that influence the diffusion of $\ce{Na+}$:
Since the potential difference is still negative, it favours influx of $\ce{Na+}$.
Since the extracellular concentration of $\ce{Na+}$ is larger than the intracellular concentration, the concentration gradient also favours influx of $\ce{Na+}$.
The following is multiple choice question (with options) to answer.
What flows across the membrane resulting in changes in the membrane potential? | [
"acids",
"neutrons",
"ions",
"electrons"
] | C | |
SciQ | SciQ-3889 | electrochemistry, redox, equilibrium, ph, concentration
Therefore, if you link two Standard Hydrogen Electrodes, you won't be able to measure a voltage.
If you don't intend to have standard conditions however, the reduction will indeed take place in the more acedic half-cell (simply spoken). This is also indicated by the electrode potential you calculated: -0,059V * pH. The reduction takes place in the half-cell with the higher potential and the potential you calculated increases with lower pH (more acedic solution).
The following is multiple choice question (with options) to answer.
The standard reduction potential can be determined by subtracting the standard reduction potential for the reaction occurring at the anode from the standard reduction potential for the reaction occurring at this? | [
"cathode",
"electrode",
"plasma",
"Spinner"
] | A | The standard reduction potential can be determined by subtracting the standard reduction potential for the reaction occurring at the anode from the standard reduction potential for the reaction occurring at the cathode. The minus sign is necessary because oxidation is the reverse of reduction. E°cell = E°cathode − E°anode +0.34 V = E° 2+ − E°H + /H = E° 2+ − 0 = E° Cu. |
SciQ | SciQ-3890 | proteins, food, digestive-system, amino-acids, digestion
Title: How are proteins reused in the body? Part of what we eat are proteins,
and our body is in part build of proteins.
Are the proteins of the body build based on proteins in food at all?
Are proteins in food directly reused in the body,
or are proteins first disassembled?
How far are they disassembled, randomly in various pieces, or systematically to keep what can optimally be used to build new proteins, while nothing is wasted for energy?
(The question Can proteins/peptides pass through the intestine? and it's answers are related, and provide some context and relevant parts, but is not a duplicate.) Short answer: Indeed the proteins in our body are based on amino acids from external food sources. BUT, proteins up-taken from food are ALWAYS disassembled first into amino acids, through specialized enzymes, proteases, (for instance Pepsin in the stomach's gastric juices and Tripsin in the pancreatic juices), during digestion, in the alimentary canal, (gut). This enables the body's liver to build the proteins most needed by the organism itself, through the processes of transamination, that allows conversion betwixt amino acids, and deamination, that removes N2 from the amino acid, (let's say the "amino" part is removed, and then expelled as urea), to excrete amino acids in excess. In addition this breaking down of external proteins is necessary, since they can act as labels for pathogens, and external organisms in general, and thus would soon be destroyed by the immune system if reused straight away.
The following is multiple choice question (with options) to answer.
What are proteins made up of? | [
"atoms acids",
"amino acids",
"lewis acids",
"detected acids"
] | B | Proteins are formed when hundreds or even thousands of amino acids form amide bonds to make polymers. Proteins play a crucial role in living organisms. A carbohydrate is a compound that has the general formula Cn(H2O)n. Many carbohydrates are relatively small molecules, such as glucose:. |
SciQ | SciQ-3891 | protein-structure, structural-biology, protein-folding
I would conclude by noting that although the individual components of these cellular polyproteins interact with one another to cooperate in the biosynthesis, the flexibility they exhibit allows transfer of the growing substrate from one component to another.
The following is multiple choice question (with options) to answer.
What proteins synthesized in cells act as catalysts? | [
"byproducts",
"virophages",
"enzymes",
"hormones"
] | C | Chemical reactions constantly occur inside the cells of living things. However, under the conditions inside cells, most biochemical reactions would occur too slowly to maintain life. That’s where enzymes come in. Enzymes are catalysts in living things. Like other catalysts, they speed up chemical reactions. Enzymes are proteins that are synthesized in the cells that need them, based on instructions encoded in the cells’ DNA. |
SciQ | SciQ-3892 | the-sun, solar-system, earth, star-formation, planetary-formation
Earth Composition
Iron 32.1%
Oxygen 30.1%
Silicon 15.1%
Magnesium 13.9%
Sulfur 2.9%
Nickel 1.8%
Calcium 1.5%
Aluminum 1.4%
Other 1.2%
A couple things I notice. The sun is quite homogenous compared to earth! It is mostly composed of just two elements whereas on earth no single element makes up more than 32% of the planet's mass.
Also, there is extremely little overlap in the elements: hydrogen and helium are the only game in town on the sun, but are nearly nonexistent on earth.
This makes me very curious! What aspect of the process of the formation of the solar system was responsible for essentially segregating these elements? Is it simply that the heavier elements were "burned" away in the hotter environment of the sun, or is there some other explanation? The composition of the Sun is close to the composition of the universe as a whole. It's the Earth that's the outlier. If you look up the elemental composition of the universe as a whole, you'll see numbers for hydrogen and helium almost identical with the ones for the Sun. Theory can predict the elemental ratios. The universe started out as entirely hydrogen, and helium and a few light elements like lithium were created in the big bang. Heavier elements like oxygen and iron were made in stars, and elements heavier than iron are largely from supernovae. But enough background, let's answer your question.
Earth, along with the other planets, formed from the same cloud of dust and gas as the Sun. The cloud started out with the same elemental composition as the Sun. The cloud collapsed under the force of gravity, and somehow chunks of material (called planetesimals) started to coalesce into planets (nobody is really certain how this process worked). The proto-Sun started to emit light and warm up the surroundings. The regions closer to the Sun, where the Earth was forming, got hot enough that light elements like hydrogen evaporated from the planetesimals. Left behind were heavier elements like oxygen, silicon (which make up most rocks) and iron. The lighter elements ended up further out, which is why Jupiter has a hydrogen-rich atmosphere.
The following is multiple choice question (with options) to answer.
What element is the sun mostly made up of? | [
"hydrogen",
"manganese",
"helium",
"mercury"
] | A | The Sun is mostly hydrogen with smaller amounts of helium. The material is in the form of plasma. |
SciQ | SciQ-3893 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
What shape is the gametophyte in ferns? | [
"circular",
"diamond",
"rectangular",
"heart-shaped"
] | D | In ferns, the sporophyte is dominant and produces spores that germinate into a heart-shaped gametophyte. |
SciQ | SciQ-3894 | the-moon
But, arguably, it's still less red than a sunset. Why is the moon's reddening less obvious than the sun's?
The moon is already a little reddish
I think it's important to think about what 'reddening' means. You said "the spectrum of moonlight is more redshifted than that of the sun, which should contribute to an even more intense reddening" -- but that's actually the opposite of the case. (I would not use the term "red shift" in this context; that term has a specific astronomical meaning related to relativistic speeds.)
The sun at the horizon turns red because the blue light is being scattered by the atmosphere (contributing to blue skies for the day side of the world), and the red passes straight through. Consider if the sun produced only red light -- then you would see no additional reddening near the horizon because there's no blue light to remove from it.
So if the moon's spectrum is already redder than the sun's, then we would expect its reddening to be less intense than the sun's, not more -- there's not as much blue light to remove, so the change is smaller. The moon may be as red or redder than the sun from an objective "I am measuring light frequencies" perspective, but if you take two moon photos, one at the horizon and one high in the sky, and lay them side by side, the difference will be less impressive.
How red is the sun, really?
In your question you state that the sun "turn[s] bright red when it's close to the horizon", but I don't think that's true. Not every sunset features a really red sun; a middling orange is far more common. The deep crimson is usually something you usually only see when there's a lot of particulate in the atmosphere, such as from a volcanic eruption or large fire. So I don't think the sun's color shift is as dramatic as you think, and thus the moon's less dramatic color shift matches it more closely than you're expecting. The moon does indeed turn a deep blood red when the atmospheric conditions are right for it.
The following is multiple choice question (with options) to answer.
What makes sunsets appear red? | [
"wavelength scattering",
"floral scattering",
"reflection scattering",
"rayleigh scattering"
] | D | Beautiful sunsets are another manifestation of Rayleigh scattering that occurs when light travels long distances through the atmosphere. The blue light and some green is scattered away, making the sun appear red. |
SciQ | SciQ-3895 | newtonian-mechanics, forces, reference-frames, free-body-diagram
Please provide some visual examples Like men walking on plank, wedge mass system.
I gave you the example of an object/earth system. I'm not quite sure what you mean by "men walking on a plank" or a "mass wedge system", but whatever they mean, you can apply the criteria given above if you define what constitutes the system in each case.
Hope this helps.
The following is multiple choice question (with options) to answer.
Skeletal and muscular are examples of what type of system? | [
"interior system",
"internal system",
"shell system",
"organ system"
] | D | Organs are organized into organ systems such as the skeletal and muscular systems. |
SciQ | SciQ-3896 | photons, material-science, absorption, optical-materials, glass
There are further complications to all of this as well. Will the light undergo scattering processes that may allow the light to move through a material, while changing directions and potentially even turning back on itself without being absorbed? Once light has been absorbed, does it simply dissipate the excess energy through the material as heat, fluoresce it back as visible light (and in what direction?), or even do more "forbidden" transitions such as phosphorescence? The answer to all of these questions is "yes, but in varying degrees specific to the material." It even depends on the physical size and amount of material that you have present! So your worries about the rate at which light is able to pass through different materials really just becomes a question of how likely it is for the light to become "sidetracked" as it passes through the material. The net result is an apparent change in how fast the light passes through.
So finally, we can connect all of these nuanced ideas which could each fill a book of discussion on their own (and have) to the macroscopic perspective. All of these properties, for a material like a bulky glass window pane, can be summarized with three simple parameters such as the coefficients of absorption, transmittance, and reflectance of the material. Obviously, for light moving through normal glass, there is an overwhelming victory of the transmittance effects over the absorption and reflectance effects. Of course, you have also clearly experienced that standing at an alternate angle changes the propensity of reflectance of different kinds of light, mostly because you have changed the relative orientation of the light with respect to the overarching structure of the glass itself. This is explained much more deeply within the field of chemical crystallography.
The following is multiple choice question (with options) to answer.
What is the process where light bounces back from surfaces that it cannot pass through? | [
"reflection",
"absorbtion",
"diffraction",
"direction"
] | A | Reflection of light occurs when light bounces back from a surface that it cannot pass through. If the surface is very smooth, the reflected light forms an image. |
SciQ | SciQ-3897 | species-identification, theoretical-biology, taxonomy, literature, bioluminescence
Title: Looking for the closest example of life forms similar to some mathematical patterns
Caveat: this is my first question here, it is quite interdisciplinary, but I hope to be in the correct place to ask. I am a user of Mathematics Stack Exchange since some years ago, and this question is related with some questions there (here, here whose general formula is discussed here and here).
Context: I am preparing a mathematical paper regarding a new family of dynamical systems (if you are not familiar with the concept, simplifying the idea it is a mathematical formula in which starting from a initial value, once applied to the formula the resulting value is again applied to the formula, and so on, finally the values are plotted and eventually a -sometimes interesting- pattern emerges) whose attractors (plotted patterns) in the present case seem to have unexpected pareidolic properties.
Basically some of the patterns generated by these systems show similarities with some structures of invertebrate life forms, specially insects, marine jellyfish, and zooplancton and also due to the patterns of the accumulation of points, also with life forms presenting bioluminescence properties.
For each interesting pattern so far I have tried to find the closest life form example, to compare both the model and the life form patterns.
So my target is including in the paper the closest life form similar to each mathematical pattern. Initially it is just a pareidolic coincidence, but it might be interesting if the mathematical formula can resemble models of some organic structures.
These are the ones I have been able to gather, both the model and the closest life form I found. The pictures I am using at the right side of and below the images are just for the sake of completeness (they belong to their respective owners, I do not own them, if there is any problem I will remove them, so just please let me know). The formula can be verified at the MSE links I have added at the beginning of the question and the Python code to generate them is in this link (please feel free to use it and modify it). The questions are after the examples (click to enlarge):
Patterns similar to thorax and abdomen of Bembicini wasp, head and body of Turritopsis dohrnii (inmortal jellyfish) and Tardigrade limbs:
Patters similar to Drain fly:
The following is multiple choice question (with options) to answer.
What are butterflies and bees an example of? | [
"species",
"spores",
"pollinators",
"parasites"
] | C | |
SciQ | SciQ-3898 | waves, atmospheric-science, turbulence
The clouds form if the rising air reaches the lifted condensation level before the updrafts are stopped by an inversion or stable layer. The air is (relatively) clear above the downdrafts. If the convection rolls were perfectly circular, the cloud row spacing would be twice the height of the inversion/stable layer.
Mathematically, there are many wavelength solutions to convection, but the wavelength that dominates is the fastest growing one. In the Boussinesq approximation, which is reasonably valid here, this turns out to have a wavelength of $2\sqrt{2}\sim 3$ times the height of the convecting layer, i.e. slightly flattened. (See, for example, Eq. 21 of Kuettner (1971) "Cloud bands in the earth's atmosphere: Observations and Theory".)
For typical cumulus cloud heights of $\sim 2$ km, we expect typical spacings of about $6$ km.
Wave, lee, or mountain clouds are lines of clouds downwind of an obstacle (such as a mountain range). The lines are parallel to the wind direction. These are buoyancy waves where wind pushes denser air over an obstacle (e.g. a mountain range) and it ends up above less dense air on the other side. This dense air starts to fall but it overshoots into even higher density air at lower altitude, which forces it back up, and the air ends up bouncing up and down until the oscillations die out. If the vertical temperature profile of the air then is known, it is possible to estimate the vertical buoyancy angular frequency
$$N=\sqrt{\frac{g}{\theta}\frac{d\theta}{dz}}$$
The following is multiple choice question (with options) to answer.
What are clouds that form on the ground called? | [
"canopy",
"fog",
"haze",
"smoke"
] | B | Clouds form when air in the atmosphere reaches the dew point. Clouds may form anywhere in the troposphere. Clouds that form on the ground are called fog . |
SciQ | SciQ-3899 | bond, molecules, noble-gases
Title: How do atoms of noble gases bond with each other? Noble gases have full electron shells, which virtually blocks any other element from bonding with it. However, I've heard about cases where they bond to each other - for example, helium can apparently form a dimer $\ce{He2}$.
How is this possible? Noble gases usually do not form strong bonds between their atoms - it takes a fair amount of energy to dimerise them into excimers, but those are short-lived excited molecules. Thanks to excitation, shells of the atoms aren't closed and they react, but very quickly they lose energy and become separate atoms.
With exception of weakly bound $\ce{Xe2^+}$ cation, stable compounds created from noble gases (mainly xenon) only feature bonds with other elements, typically fluorine or oxygen, but there are also, for example, organoxenon compounds.
As mentioned in the comments, you may have heard about detection of so called van der Waals molecules of helium, which aren't "true" molecules, but very weakly bound pairs of atoms. In fact helium vdW dimer may have weakest bond even among them, and it was an achievement to observe it.
The following is multiple choice question (with options) to answer.
What is formed when atoms of different elements bond together? | [
"phenotype compound",
"univalent compound",
"covalent compound",
"duality compound"
] | C | The two atoms that are held together in a covalent bond may be atoms of the same element or different elements. When atoms of different elements bond together, it forms a covalent compound. |
SciQ | SciQ-3900 | cell-biology
Title: Structure of Cell Are cells spheres or ovals/circles bound by phospholipidbilayer?
If they are spherical how are we able to see the nucleus through the phospholipid bilayer under a microscope? Not exactly. That is a stereotype of cells. Muscle cells are not round nor oval, but rather elongated rods. If you were to look up epithelia cells, you can quickly see that cells are grouped based on their physical characteristics; simple (round/oval & single layer), columnar, and cuboidal to name a few. Cells come in many shapes and sizes. As Hans stated, stains are vital in viewing cellular components. There is a diverse amount of stains used - which all carry a purpose and benefit in a specific application.
The following is multiple choice question (with options) to answer.
Where a cell resides, how it appears, and what it does define its what? | [
"development fate",
"minute race",
"life cycle",
"slowing rate"
] | A | |
SciQ | SciQ-3901 | time, popular-science
At this point I'm kind of stuck for anything further to say. If I interpret your question correctly then you do have a point that just because we observe change of position with time (i.e. movement) this doesn't necessarily mean time is flowing in the way we think. However I'm not sure this conclusion is terribly useful, and possibly it's just semantics.
The following is multiple choice question (with options) to answer.
What can be defined simply, as a change in position? | [
"velocity",
"gravity",
"speed",
"motion"
] | D | You can see several examples of people or things in motion in Figure below . You can probably think of many other examples. You know from experience what motion is, so it may seem like a straightforward concept. Motion can also be defined simply, as a change in position. But if you think about examples of motion in more depth, you’ll find that the idea of motion is not quite as simple and straightforward as it seems. |
SciQ | SciQ-3902 | mars, phobos
According to Geoffrey Landis, Deimos and Phobos could have each been moons of parent asteroids, and they were separated due to tidal forces:
This would explain how Phobos and Deimos could survive as moons. I could mention the other hypotheses, but Landis' would answer your question quite well.
Right now, there isn't any clear consensus as to how Phobos and Deimos became moons. More research is still necessary, and we may need to modify our models for the evolution of Mars and the asteroid belt.
The following is multiple choice question (with options) to answer.
What are mars' moons thought to be? | [
"common asteriods",
"new asteriods",
"captured asteroids",
"guerrillas asteroids"
] | C | Mars has two moons that are thought to be captured asteroids. |
SciQ | SciQ-3903 | heat, wavelength
Title: Is carbon dioxide a greenhouse gas?
Possible Duplicate:
What experiments prove the greenhouse effect?
I am seeking for a proof that CO2 is a greenhouse gas. I posted this on Skeptic.SE recently but found no help in seeking for proof:
I assisted to a physicist conference in my university a few years ago
against the case that carbon dioxide was a cause of global warming.
The main point was that CO2 is not a greenhouse gas. I did a
research to find evidence for either side and found absolutely
nothing.
So, is carbon dioxide a greenhouse gas? If yes, has it been
demonstrated in a scientific paper?
Here are some discussion articles describing arguments against CO2
being a greenhouse gas:
The following is multiple choice question (with options) to answer.
What is the main greenhouse gas causing global warming? | [
"nitrogen",
"carbon dioxide",
"carbon monoxide",
"sulfur"
] | B | Carbon dioxide is the main greenhouse gas causing global warming. There are several possible ways to reduce carbon dioxide emissions. They include cap-and-trade systems, carbon taxes, and carbon sequestration. |
SciQ | SciQ-3904 | analytical-chemistry
Title: Easy method of analysing iodine content in supplements? Most health-food stores carry supplements supposedly containing iodine for people with iodine deficiency. I recently bought some kelp tablets that are supposed to have iodine but as a consumer how can I be sure that there is any iodine in them at all, let alone the claimed minimum daily requirement.
How do I know that I'm not just taking green-colored sawdust? Is there a cheap way to test a kelp tablet for its iodine content? If not are there testing labs that I could send some kelp to for testing that isn't going to cost me thousands of dollars? Take some potato starch dissolved in water (you can easily get it from the water when you boil potatoes), and put a tablet into the water. If the water becomes bluish black, there is iodine in the tablet.
Yes, there are testing labs that will determine the amount of iodine in the tablets which will cost somewhere around \$100 to \$200.
The following is multiple choice question (with options) to answer.
A goiter is a visible indication of deficiency of what? | [
"water",
"arsenic",
"iodine",
"chlorine"
] | C | Endocrine System: Iodine Deficiency, Hypothyroidism, and Hyperthyroidism As discussed above, dietary iodine is required for the synthesis of T3 and T4. But for much of the world’s population, foods do not provide adequate levels of this mineral, because the amount varies according to the level in the soil in which the food was grown, as well as the irrigation and fertilizers used. Marine fish and shrimp tend to have high levels because they concentrate iodine from seawater, but many people in landlocked regions lack access to seafood. Thus, the primary source of dietary iodine in many countries is iodized salt. Fortification of salt with iodine began in the United States in 1924, and international efforts to iodize salt in the world’s poorest nations continue today. Dietary iodine deficiency can result in the impaired ability to synthesize T3 and T4, leading to a variety of severe disorders. When T3 and T4 cannot be produced, TSH is secreted in increasing amounts. As a result of this hyperstimulation, thyroglobulin accumulates in the thyroid gland follicles, increasing their deposits of colloid. The accumulation of colloid increases the overall size of the thyroid gland, a condition called a goiter (Figure 17.14). A goiter is only a visible indication of the deficiency. Other iodine deficiency disorders include impaired growth and development, decreased fertility, and prenatal and infant death. Moreover, iodine deficiency is the primary cause of preventable mental retardation worldwide. Neonatal hypothyroidism (cretinism) is characterized by cognitive deficits, short stature, and sometimes deafness and muteness in children and adults born to mothers who were iodinedeficient during pregnancy. |
SciQ | SciQ-3905 | human-evolution, skin
Title: Why did evolution make people's skin dark? Why do people living in the equator have dark skin?
I know that Melanin acts as a protective biological shield against ultraviolet radiation.
But doesn't black absorb all light in a way making the body more heated than the surroundings ? It didn't, the basal condition for humans is dark skin, all other pigmentation patterns evolved from it. Additionally Dark skin is not monophyletic/homologous in humans,
that is some darks skinned humans evolved from light skinned humans who in turn evolved from ancestral dark skinned humans, (Evolution made skin lighter then made it darker again in other regions). Skin dark/lightness is also well correlated with latitude (which is correlated with UV levels).
First it helps if you remember skin is translucent so even very light skin absorbs a great deal of light. Additionally black also radiated heat better than white its is a double edged sword so to speak, it absorbs heat better but also sheds it better.
But the current hypothesis about why light skin evolved is due to vitamin D. The skin absorbs some UV radiation to manufacture vitamin D. Dark skin blocks more of this radiation reducing vitamin D levels. As humans migrated into higher latitudes with less UV radiation they needed lighter skin to harvest more of it. If your skin is too light you have issues with sunburn, skin cancer, and folic acid destruction darker skin protects from these. Now in modern humans clothing and diet completely swamps these effects, so studying it is difficult. the use of clothing in humans moving into colder climates may have exacerbated this effect. The later evolution of lactase persistence could further confuse the effect.
Note that this hypothesis is controversial and only weakly supported because it is extremely difficult to test and the the multiple confounding factors.
http://evolution.berkeley.edu/evolibrary/news/140305_skincolor
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3024016/
https://www.ncbi.nlm.nih.gov/pubmed/16766240
https://dl.dropboxusercontent.com/u/38568440/admixture/shriver01.pdf
https://en.wikipedia.org/wiki/Human_skin_color
The following is multiple choice question (with options) to answer.
Pale skin and reduced eyes in salamanders that live in dark caves are an example of what? | [
"adaptations",
"expansion",
"interpretation",
"reproduction"
] | A | Salamanders are found in most moist or arid habitats in the Northern Hemisphere, but can also be found south of the equator. They live on all continents except Antarctica and Australia. Salamanders live in or near water or on moist ground, often in a swamp. Some species live in water most of their life, some live their entire adult life on land, and some live in both habitats. Some salamanders live in caves. These salamanders have pale skin and reduced eyes as they have adapted to living in complete darkness in underground pools of water. The reduced eyes are similar to other organisms that live in caves or underground. |
SciQ | SciQ-3906 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
Kidney stones are considered a disease that affects which system? | [
"reproductive system",
"digestive system",
"muscular system",
"urinary system"
] | D | Diseases of the urinary system include kidney stones and urinary tract infections. Untreated diabetes may cause kidney failure and the need for hemodialysis or a kidney transplant. |
SciQ | SciQ-3907 | acid-base, equilibrium, aqueous-solution, ph, environmental-chemistry
$[H^+] = 10^{-pH}$
$[OH^-] = \frac{K_w}{[H^+]}$
$[CO_{2(aq)}] = \frac{p_{CO_2}}{K_{H,CO_2,25^\circ C}} = 1.36E-05$ (Constant at all pH)
$[HCO_{3(aq)}^-] = \frac{(K_1\times [CO_{2(aq)}])}{[H^+]}$
$[CO_{3(aq)}^{2-}] = \frac{(K_2\times [HCO_{3(aq)}^-])}{[H^+]}$
Where the molar balance of $CO_{2(aq)}$, termed "TOTCO2" can be defined as:
$TOTCO2 = [CO_{2(aq)}] + [HCO_{3(aq)}^-] + [CO_{3(aq)}^{2-}]$
And the calculated a charge balance ($CB$) on the system where $z$ is the species' ionic charge:
$CB = \sum{z\times[positive\,ions]}=\sum{z\times [negative\,ions]}$
The CB is thus;
$ [H^+] = [OH^-] + [HCO_{3(aq)}^-] + 2[CO_{3(aq)}^{2-}]$
The relative speciations (a [mol%]) are thus:
$ a_{CO_2} = \frac{[CO_{2(aq)}]}{TOTCO2}$
$ a_{HCO_{3}^-} = \frac{[HCO_{3(aq)}^-]}{TOTCO2}$
The following is multiple choice question (with options) to answer.
The concentration of hydrogen ions in a solution is called? | [
"alcohol",
"moisture",
"alkalinity",
"acidity"
] | D | The strength of acids and bases is determined by the concentration of ions they produce when dissolved in water. The concentration of hydrogen ions in a solution is called acidity. It is measured by pH. A neutral substance has a pH of 7. An acid has a pH lower than 7, and a base has a pH greater than 7. |
SciQ | SciQ-3908 | electronic-configuration, atoms, ionization-energy
Title: Why does increasing subshell cause ionization energy to decrease? I know that increasing subshell decreases ionization energy; for example, going from Beryllium to Boron. I do not understand why this is.
The answer my textbook (Chemistry 2e on OpenStax) gives is that the higher subshells (eg $\ce{p}$) has more energy than the lower subshells (eg $\ce{s}$). I do not understand why a higher energy subshell require more energy to remove (ie more ionization energy)? Is it as if the higher energy subshell is less stable, and thus has lower ionization energy? I think in order to understand this phenomenon you have to consider what is happening during an ionization. During this process we are removing a single electron from our molecule or atom. The electron we are going to remove will be the one which is easiest to remove (the one we require the least amount of energy to remove).
Having this in mind, we can take the knowledge that the electron shells keep increasing in energy so e.g. 2s < 2p. "Higher in energy" means that they are less bound to the nucleus (that's just the way we usually define our energy scale).
Thus when combining these two, we can understand why the ionization energy decreases when ionizing atoms that have electrons in higher shells.
The probably more interesting question here is probably why the energy of the shells keeps increasing. To break it down the reason is that electrons in higher shells have (on average) a larger distance to the nucleus. As the electrostatic potential (which is is the main interaction between electron and nucleus) is proportional to the inverse distance (search for "Coulomb potential" if you want more details), this means that these electrons just feel less and less of the attraction from the nucleus which causes them to be more easily removed.
Another effect that plays into this is called "shielding" and it essentially means that the electrons from the lower shells will shield the nucleus' positive charge to some degree and thus the outer electrons the ones in the higher shells) will feel less attractive force to begin with.
The following is multiple choice question (with options) to answer.
Within a group, the ionization energy decreases as the size of the atom gets what? | [
"larger",
"lighter",
"brighter",
"smaller"
] | A | Within a group, the ionization energy decreases as the size of the atom gets larger. On the graph, we see that the ionization energy increases as we go up the group to smaller atoms. In this situation, the first electron removed is farther from the nucleus as the atomic number (number of protons) increases. Being farther away from the positive attraction makes it easier for that electron to be pulled off. |
SciQ | SciQ-3909 | zoology
Title: What is the reason for cats not liking water? I have two cats myself, a Siberian and a Maine Coon, neither of which like water. In fact, they detest it - like most cats. I was wondering what the reason for this was and if any of you have any interesting theories as to why this is the case.
Thanks in advance! First, some cats do like water. But it seems true (from personal observation and most people's opinion) that most cats don't.
The question has already been asked many times online. Just Google your question!
I doubt one will find peer-reviewed papers on the question but below is a summary of what seem to be the most often mentioned possible reasons I could find. Of course, these bullet points are very hypothetical and I don't know of any research presenting evidence for or against these hypotheses.
Their fur is not really adapted for the water and will very quickly become waterlogged and heavy making it uncomfortable.
Cats are generally speaking quite skittish
Cats may not like the odour of chemicals we put in the water.
Cats love to groom themselves. It is an aweful lot of work to do the grooming after a bath.
Note also that domestic cats are descendent from cats living in very arid areas. The most closely related species with cats are the African Wildcat living in Northern Africa, the Near East and around the periphery of the Arabian Peninsula.
Source
My non-peer reviewed sources are
http://www.petful.com/behaviors/why-do-cats-hate-water/
http://www.animalplanet.com/pets/healthy-pets/do-cats-really-hate-water/
http://www.petguide.com/blog/cat/why-do-cats-hate-water/
The following is multiple choice question (with options) to answer.
Temperature can affect what attribute of a siamese cat's coat? | [
"chemical makeup",
"density",
"color",
"weight"
] | C | Genes play an important part in influencing phenotype, but genes are not the only influence. Environmental conditions, such as temperature and availability of nutrients can affect phenotypes. For example, temperature affects coat color in Siamese cats. |
SciQ | SciQ-3910 | newtonian-mechanics, energy, everyday-life, biophysics
Running involves more and varied movements, it's a very different gait. It is definitely not just the same movement as walking but faster. Some of those movements are vertical, or relate to jumping, some have shock absorption components and relate to landing. Much of that extra energy is dissipated both ways - we use energy both to jump and to cushion and come to a halt on landing. We also accelerate our feet to match our ground speed and must slow them to zero each stride, then speed and lift the other way as well, not just rely on gravity and pendulum activity. The fact this is at extension and not at ground impact doesn't change anything. Again, energy is lost both ways. I'm also going to guess that it's harder to be efficient across a wider compared to narrower range of motions, therefore the wider range of movements and systems used in running means it's much more likely that efficiency varies considerably, according to biological subsystem or type of movement.
Human gross muscle motion energy handling/metabolism is not efficient and doesn't behave like an ideal object. We have multiple energy pathways, and switch between them according to need. This happens less with walking, more with vigorous exercise like running. The "emergency" or "sustained activity" energy cycle our bodies switch to, when running, is less efficient - if it was more efficient it would probably have evolved as our primary not our fallback. And of course many biochemical reactions and body responses just aren't linear; they also may have min/max rates or durations.
The following is multiple choice question (with options) to answer.
What type of locomotion do humans have? | [
"crawling",
"bipedal",
"elongated",
"quadrupedal"
] | B | 34.8 Humans are mammals that have a large brain and bipedal locomotion. |
SciQ | SciQ-3911 | thermodynamics, heat, ideal-gas
Title: Combined gas law in an open atmosphere The question was asked about pressure vs. Volume increasing in an ideal gas as temperature is increased. My question then is this. What is the formula to determine how much volume and pressure will increase as temperature is increased?
Let me frame the question this way. PV/T=P2V2/T2 this formula works for a controlled system where more than one of these values can be maintained. If we apply a known amount of heat, say n, to the atmosphere, what formula would be used to calculate volume and pressure as the temperature is increased? Technically speaking, If you managed to create a planet with an ideal gas atmosphere, the atmosphere would just float away. Why?
One of the approximations of an ideal gas is
There are no attractive or repulsive forces between the molecules or the surroundings
This means that the gas wouldn't feel the force of gravity!
So if I had a jar of ideal gas, the pressure wouldn't increase as I went to a greater depth in the jar(It does increase in gasses too, just like it does in liquids).
I know this sounds strange but all it really means is that you cannot apply the ideal gas approximation to a system the size of our atmosphere. This approximation works well for small systems(A jar of ideal gas), because the effects of gravity are pretty negligible.
So to analyse effects of change in temperature on the whole atmosphere, you'll need a better model. Maybe considering the atmosphere a non-viscous fluid can help, I don't know. You should research on this.
Note that other approximations like the Van der Waals equation wouldn't help too because they too neglect the effect of gravity.
The following is multiple choice question (with options) to answer.
Which equation improves upon the ideal gas law by adding two terms: one to account for the volume of the gas molecules and another for the attractive forces between them? | [
"Pascal's equation",
"Newton's third law",
"Heidiger's principle",
"van der waals"
] | D | There are several different equations that better approximate gas behavior than does the ideal gas law. The first, and simplest, of these was developed by the Dutch scientist Johannes van der Waals in 1879. The van der Waals equation improves upon the ideal gas law by adding two terms: one to account for the volume of the gas molecules and another for the attractive forces between them. |
SciQ | SciQ-3912 | reaction-mechanism, quantum-chemistry
Title: Chemical reaction energy barrier width Well chemistry before the discovery of quantum world was saying:"In order for a chemical reaction to happen , reactants must have enough energy to be converted into products."I was wondering now that we have discovered quantum worlds and quantum properties and quantum effects and quantum tunneling , maybe if the energy barrier is very narrow then we dont have to add this "Activation energy" and the reactants pass through this energy barrier to create products . Tunneling can be important for any reaction where there is a proton or electron transfer involved and the electron/proton donor/acceptor are placed in a "sweet spot" that increases the importance of this over other mechanisms.
As explained here, the conditions for appreciable contribution of tunneling to a reaction mechanism are that (1) the activation barrier be large enough (otherwise tunneling is not necessary); (2) the width of the barrier (the tunneling distance) should not be too great and (3) the particle must have significant wave (delocalized) character, that is, small mass (such as a proton or electron).
The following is multiple choice question (with options) to answer.
What do chemical reactions need to be activated? | [
"space",
"food",
"energy",
"products"
] | C | Chemical reactions also need energy to be activated. They require a certain amount of energy just to get started. This energy is called activation energy . For example, activation energy is needed to start a car engine. Turning the key causes a spark that activates the burning of gasoline in the engine. The combustion of gas won’t occur without the spark of energy to begin the reaction. |
SciQ | SciQ-3913 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
Compared to thoracic and lumbar types, the cervical type of what structures carry the least amount of body weight? | [
"nasal",
"vertebrae",
"nuclei",
"ametic"
] | B | Cervical Vertebrae Typical cervical vertebrae, such as C4 or C5, have several characteristic features that differentiate them from thoracic or lumbar vertebrae (Figure 7.25). Cervical vertebrae have a small body, reflecting the fact that they carry the least amount of body weight. Cervical vertebrae usually have a bifid (Y-shaped) spinous process. The spinous processes of the C3–C6 vertebrae are short, but the spine of C7 is much longer. You can find these vertebrae by running your finger down the midline of the posterior neck until you encounter the prominent C7 spine located at the base of the neck. The transverse processes of the cervical vertebrae are sharply curved (U-shaped) to allow for passage of the cervical spinal nerves. Each transverse process also has an opening called the transverse foramen. An important artery that supplies the brain ascends up the neck by passing through these openings. The superior and inferior articular processes of the cervical vertebrae are flattened and largely face upward or downward, respectively. The first and second cervical vertebrae are further modified, giving each a distinctive appearance. The first cervical (C1) vertebra is also called the atlas, because this is the vertebra that supports the skull on top of the vertebral column (in Greek mythology, Atlas was the god who supported the heavens on his shoulders). The C1 vertebra does not have a body or spinous process. Instead, it is ring-shaped, consisting of an anterior arch and a posterior arch. The transverse processes of the atlas are longer and extend more laterally than do the transverse processes of any other cervical vertebrae. The superior articular processes face upward and are deeply curved for articulation with the occipital condyles on the base of the skull. The inferior articular processes are flat and face downward to join with the superior articular processes of the C2 vertebra. The second cervical (C2) vertebra is called the axis, because it serves as the axis for rotation when turning the head toward the right or left. The axis resembles typical cervical vertebrae in most respects, but is easily distinguished by the dens (odontoid process), a bony projection that extends upward from the vertebral body. The dens joins with the inner aspect of the anterior arch of the atlas, where it is held in place by transverse ligament. |
SciQ | SciQ-3914 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
Many plants generate root pressure during which phase? | [
"developing season",
"growing season",
"end of life cycle",
"flowering season"
] | B | |
SciQ | SciQ-3915 | nuclear-engineering
Title: How do nuclear power plants prevent fuel rods from depleting nonuniformaly? Power output of nuclear reactors is controlled by control rods that sit in between the fuel rods:
These are pulled out to increase fission rates - and lowered to decrease them.
The control rods are made from neutron absorbing materials - such as cadmium.
When lowered completely, so many neutrons are absorbed, that no chain reaction is maintained. Pulling them out increases the neutrons that are available for fission.
My question:
The lower tips of the fuel rods will almost always be exposed to neutrons, so these should burn down much faster (have their uranium fissioned) than the upper parts that rarely have the control rods removed from them. Is there some engineering going on to have the fuel rods burn down at the same rate along their whole length? I'm going to answer this for a LWR, since I guess that's what you're thinking of.
First of all, the premise of the question is not quite correct. The power distribution of an LWR is generally sinusoidal, with a peak towards the middle of the fuel. This is true with or without control rods inserted. The most common power reactor design in operation--a conventional PWRs operating in full-power baseload operation--does not have control rods deeply inserted into the core for any significant amount of time. This shape is driven by a few factors: first, fast neutrons tend to 'leak' out of the core without thermalizing more towards the extremities. Additionally, because the top of the fuel has a higher moderator temperature (or maybe even some voids!), this also leads to less thermalization there. So, because of the shape of the power distribution, the tops and bottoms of the fuel assembly have far less power (and therefore less relative depletion) than the 'middle' of the fuel.
The following is multiple choice question (with options) to answer.
The fuel rods are made of a corrosion-resistant alloy that encases the partially enriched uranium fuel; controlled fission of 235u in the fuel produces heat. water surrounds the fuel rods and moderates this? | [
"thermal energy",
"kinetic energy",
"half-life",
"electromagnetism"
] | B | The fuel rods are made of a corrosion-resistant alloy that encases the partially enriched uranium fuel; controlled fission of 235U in the fuel produces heat. Water surrounds the fuel rods and moderates the kinetic energy of the. |
SciQ | SciQ-3916 | earthquakes, waves, scale
Title: If a very huge Earthquake occured anywhere on Earth could waves emerge to come together again on the opposite side? Suppose that a super-powerful earthquake occurred anywhere on Earth, say one with the value 10 on Richter's scale. The quake can have any value but as can be read in a comment below the highest value ever measured was 32 on a superdense star. In that case, it's much more difficult to tear the star apart. The Earth, in contrast, could be torn apart by a quake with value 10 because she is highly less massive.
Suppose the quake was mainly transversal (in a vertical direction). Could it be that correspondingly waves emerged from the center of the quake, traveling the Earth around to come together and reinforced again on the opposite side of the center, with the effect that the quake was felt more strongly on the opposite side of the center than at places halfway from the center (or halfway to the opposite side of the center), to say it in one long breath? Or would too much energy be absorbed from the waves by the Earth to reach the opposite side? It is called "antipodal focusing". See for example Antipodal focusing of seismic waves observed with the USArray.
We present an analysis of the M-w = 5.3 earthquake that occurred in the Southeast Indian Ridge on 2010 February 11 using USArray data. The epicentre of this event is antipodal to the USArray, providing us with an opportunity to observe in details the antipodal focusing of seismic waves in space and time. We compare the observed signals with synthetic seismograms computed for a spherically symmetric earth model
The above paper deals with "body waves" that travel through the interior of the Earth.
There are also Rayleigh waves that travel on the surface and can travel around the Earth several times before dissipating (Wikipedia). Antipodal focusing of seismic waves due to large meteorite impacts on Earth does numerical simulations of surface waves at the antipode of the Chicxulub impact. The waves do not arrive at the antipode at the same time because of Earth’s ellipsoidal shape and different rock properties along their paths.
Isosurfaces of the norm of the peak displacement vector after a vertical impact for the impact hemisphere (left-hand side) and antipodal hemisphere (right-hand side).
The following is multiple choice question (with options) to answer.
Earthquake waves that travel trhough underground rocks in all directions are known as? | [
"typical waves",
"tertiary waves",
"secondary waves",
"primary waves"
] | C | Another example of transverse waves occurs with earthquakes. The disturbance that causes an earthquake sends transverse waves through underground rocks in all directions from the disturbance. Earthquake waves that travel this way are called secondary, or S, waves. An S wave is illustrated in Figure below . |
SciQ | SciQ-3917 | 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.
What is the final product of the calvin cycle? | [
"insulin",
"glucose",
"sucrose",
"chloride"
] | B | The final product of the Calvin cycle is glucose. |
SciQ | SciQ-3918 | electromagnetism, electromagnetic-induction, relative-motion
Title: In magnet and conductor problem, what is the source of electric field? I have difficulty understanding forces involved in moving magnet and conductor problem.
When a ring conductor is at rest and an ordinary bar magnet is moving, there's electric force. I have trouble understanding how the electric force arise here. Based on my understanding of Faraday's law, there should be induced current flowing in the ring conductor. So the electric force is responsible for creating current?
Here is what I mean by electric force creating current: Consider this example where the magnetic field out the page is moving to the left towards the stationary wire loop
Faraday's law tells me that the current should be flowing clockwise. I am not sure what are forces involved here. There is no magnetic force since the loop is stationary so there's electric force somewhere and I'm not sure where it came from and its direction. According to this equation $\nabla \times \vec{E} = -\frac{\partial \vec{B}}{\partial t}$, it looks like there is electric field flowing clockwise direction like the current. So the clockwise electric field which produces electric force is responsible for creating clockwise current?
Take a look at this image from this Wikipedia article,
I understand where the magnet force is coming from in the magnet frame (one with blue coordinates). But in the conductor frame (one with primed red coordinates), I have trouble understanding where the electric force came from. I don't know the source of electric field and why it points downwards. Also, I'm not sure why the primed red coordinates is moving in +x direction (see the dotted arrow). It is supposed to move in -x direction?
According to this equation $\nabla \times E = -\frac{\partial B}{\partial t}$, it looks like there is electric field flowing clockwise direction like the current. So the clockwise electric field which produces electric force is responsible for creating clockwise current?
Yes.
The following is multiple choice question (with options) to answer.
What does an electric conductor cross to generate current? | [
"magnetic field lines",
"waves field lines",
"magnetic polar waves",
"magnetic zone waves"
] | A | A changing magnetic field produces an electric current in the process of electromagnetic induction. Current is generated whenever an electric conductor crosses magnetic field lines. |
SciQ | SciQ-3919 | fusion
Title: Where does the energy produced by fusion come from? Fission, in layman's (or "initiate's") terms, is easy enough to understand; a large atom with a lot of protons and neutrons requires a large amount of force provided by the strong interaction to overcome electromagnetism and keep the nucleus together. The necessary energies were imparted to the atom during its formation, which we can replicate to some degree within a nuclear reactor; a combination of heat and fast-moving free protons/neutrons recaptured by the atoms of the fuel turns uranium into plutonium, even as the actual atom-splitting produces much lighter krypton and barium isotopes (or a host of other possibilities, some more likely than others, as with many other types of reactions). That atom-splitting, by the way, reduces the size of the resulting nuclei, and therefore reduces the amount of strong interaction force required to contain them; the leftover energy is released as a high-frequency gamma photon.
Fusion, however, is an odder beast. A fusion reaction requires a large amount of starting energy; enough to strip the electrons off of the deuterium/tritium nuclei and form plasma. That heat is also enough to accelerate the particles fast enough that when they collide, the initial electromagnetic repulsion is overcome and the strong interaction binds them together.
Now, that's a lot of energy required; the Sun's inner core where most of the fusion occurs is estimated to be about 15 million Kelvin. The reaction, however, doesn't seem to release any energy, based at least on this simplistic explanation. Now, obviously that's wrong; pretty much all the energy we have available to us right now is, however indirectly, a result of the Sun bathing us in the energy from nuclear fusion. The rest of it, such as from nuclear fission, is also star-based, via creation of superheavy elements in stellar nucleogenesis.
The following is multiple choice question (with options) to answer.
Splitting the nucleus of an atom produces a massive amount of what type of energy? | [
"nuclear energy",
"likely energy",
"radioactive energy",
"sure energy"
] | A | Nuclear energy is produced by splitting the nucleus of an atom. This releases a huge amount of energy. |
SciQ | SciQ-3920 | # How to solve time dependent pde?
I have set out to try and solve a time dependent wave equation with specific boundary conditions, but I am running into a bit of a snag. As you can see, I am trying to solve for the wave function u[t, x] traveling at velocity 1, with my boundary conditions being a fixed point at u[t, 30], and a Gaussian wave packet at t = 0.
difeqns = {D[u[t, x, {t, 2}] - D[u[t, x], {x, 2}] == 0,
u[t, 30] == 0,
u[0, x] == E^(-x^2),
Derivative[1, 0][u][0, x]== 0}
I am plotting my solution as a variable of time holding n constant at 20 using the code:
solv = NDSolve[difeqns, u[t, x], {t, 0, 500},
{x, -30, 30},
WorkingPrecision -> 5, InterpolationOrder -> All];
x= 20
Plot[u[t, x]/. solv, {t, 0, 500}, PlotRange -> All]
Since there is a fixed point set at u[t, 30], I expect the initial Gaussian wave packet to reflect off of the fixed point on the right side and then continue onto negative infinity, so as time goes on, no oscillation at all should occur. However, my oscillation is not going to zero at x=20 as time increases, and when I animated my solution using ListAnimate, it seemed like the wave packet was reflecting off of a boundary on the left side even though no such boundary should exist. What have I done wrong in my numerical approach to this problem?
The following is multiple choice question (with options) to answer.
What are waves that pass a fixed point in a given amount of time called? | [
"wave frequency",
"tendency frequency",
"combination frequency",
"radio frequency"
] | A | The number of waves that pass a fixed point in a given amount of time is wave frequency . Wave frequency can be measured by counting the number of crests (high points) of waves that pass the fixed point in 1 second or some other time period. The higher the number is, the greater the frequency of the waves. The SI unit for wave frequency is the hertz (Hz) , where 1 hertz equals 1 wave passing a fixed point in 1 second. The Figure below shows high-frequency and low-frequency transverse waves. You can simulate transverse waves with different frequencies at these URLs: http://phet. colorado. edu/en/simulation/wave-on-a-string and http://zonalandeducation. com/mstm/physics/waves/partsOfAWave/waveParts. htm. |
SciQ | SciQ-3921 | physical-chemistry, solubility
Title: At what point does decreasing solvent temperature cause a decrease in gas solubility? Example: At constant pressure, carbon dioxide becomes less soluble in water as temperature increases. We also know that carbon dioxide becomes more soluble in water as temperature decreases.
Does introduction of order and loss of kinetic energy of solvent molecules eventually lead to a decrease in a solvent's ability to accommodate gas molecules? It is hard for me to believe that ice cubes can hold gas more effectively than the same volume of a glass of water. Rules such as "solubility of A in B rises with lower temperature" are only meant to be used if there is no phase transition of the participating substances.
The following is multiple choice question (with options) to answer.
As temperature increases, the solubility of the majority of solid substances does what? | [
"reduces",
"increases",
"stays the same",
"mutates"
] | B | The solubility of the majority of solid substances increases as the temperature increases. However, the effect is difficult to predict and varies widely from one solute to another. The temperature dependence of solubility can be visualized with the help of a solubility curve , a graph of the solubility vs. temperature (see Figure below ). |
SciQ | SciQ-3922 | vision, cognition, cat
general reading.
visual cortex of monkeys and cats.
Activation of the hypothalamic feeding centre upon visual prey detection
other research.
The following is multiple choice question (with options) to answer.
The process in which animals use visual cues to communicate is known as what? | [
"visual communication",
"peripheral communication",
"visual indication",
"distinctive communication"
] | A | Visual Communication in Animals. Many animals use visual cues to communicate. |
SciQ | SciQ-3923 | reaction-mechanism, equilibrium, kinetics
\begin{align}
k_1\ce{[A][B]} &\gg k_2\ce{[C][E]} \\
k_{-1}\ce{[C][D]} &\gg k_2\ce{[C][E]} \\
K_1 &= {k_1 \over k_{-1}}
\end{align}
$$
The relative values of the forward and reverse rate constants can vary, with their ratio described by $K_1$, but at all points through the reacting process of interest, both the forward and reverse equilibrium reactions are assumed to be much faster than the final, product-forming reaction. If this assumption doesn't hold, then we can't treat the first reaction as "just" an equilibrium reaction.
The following is multiple choice question (with options) to answer.
What state is achieved when the forward and reverse reactions proceed at equal rates? | [
"neutrality",
"equality",
"equilibrium",
"constant"
] | C | At equilibrium, the forward and reverse reactions proceed at equal rates. The driving force in each direction is equal, because the free energy of the reactants and products under equilibrium conditions is equivalent (ΔG = 0). We also know that, at equilibrium, Q = K eq . For a reaction that has reached equilibrium, the equation above becomes the following:. |
SciQ | SciQ-3924 | photons, atomic-physics, virtual-particles, non-linear-optics
Edit:
I removed the confusing/inaccurate image (first image above) from the photon upconversion Wikipedia page.
The following is multiple choice question (with options) to answer.
What are 3 types of light? | [
"infrared, visible, ultraviolet",
"solar , visible , ultraviolet",
"diffuse, ambient, opaque",
"complementary, incandescent, fluorescent"
] | A | Electromagnetic waves that are commonly called light fall roughly in the middle of the electromagnetic spectrum. Light includes infrared light, visible light, and ultraviolet light. |
SciQ | SciQ-3925 | homework, ecology, population-biology, conservation-biology
Title: Difference between biological control and introducing species for conservation? I have a biology assignment and we have to explain various methods and strategies for conservation, two of which are:
Biological control
Introduced Species
What is the difference between these? I was under the impression that they are essentially the same thing – biological control being the introduction of species to predate pests (eg. the abysmal failure of the cane toad).
Any clarification would be great. After talking to my teacher, he said that biological control is the introduction of species to control another species, however species may be introduced for other reasons (the "Introduced Species" method), such as to "assist an ecosystem cope, flourish or re-establish itself."
The example he gave was the introduction of South African veldt grass to Western Australia in order to stabilise sand dunes, so that they can later be built upon further (eg. plants which may not perform well in sandy, unstable soil can then be planted).
Hopefully this helps anyone else with the same problem.
The following is multiple choice question (with options) to answer.
What is an interation between organisms or species for the same resources in an enviroment is called? | [
"competition",
"contention",
"opposition",
"rivalry"
] | A | Competition is as an interaction between organisms or species for the same resources in an environment. |
SciQ | SciQ-3926 | species-identification, invertebrates
Title: Identification of odd jellyfish-like creature in the Mediterranean My parents encountered this unknown creature on a beach in Karpathos, Greece.
None of the locals have seen it before, it may be a species that has moved further north due to ocean warming.
Any ideas what it is? It seems to be a "Hula skirt siphonophore" - Physophora hydrostatica
Physophora hydrostatica, also known as hula skirt siphonophore, is a
species of siphonophores in the family Physophoridae.1
https://en.wikipedia.org/wiki/Physophora_hydrostatica
The following is multiple choice question (with options) to answer.
What type of organism, including sea stars and sand dollars, is named for their spiny skin? | [
"chordates",
"mollusks",
"echinoderms",
"diatoms"
] | C | Echinoderms are named for their “spiny skin. ” However, the spines aren’t on their skin. They are part of the endoskeleton. The endoskeleton consists of calcium carbonate plates and spines, covered by a thin layer of skin. Adult echinoderms have radial symmetry. This is easy to see in the sea star and sand dollar in Figure above . However, echinoderms evolved from an ancestor with bilateral symmetry. Evidence for this is the bilateral symmetry of their larvae. |
SciQ | SciQ-3927 | virology, nomenclature
Title: Why is it called "Ebola virus disease", not just "Ebola" or "Ebola disease"? Why do scientists (pretty consistently) call it Ebola virus disease, rather than just Ebola, or Ebola disease?
Many other diseases are caused by viruses, but they don't seem to have this detail of terminology. Nor do you hear the analogous terminology for bacteria.
For example:
The following is multiple choice question (with options) to answer.
What is the term for a disease that is not contagious? | [
"benign",
"noninfectious disease",
"common cold",
"uncultured disease"
] | B | Not all diseases are contagious. A disease that is not contagious is called a noninfectious disease. These diseases are not caused by pathogens. Instead, they are likely to have causes such as lifestyle factors, environmental toxins, or gene mutations. Common types of noninfectious diseases include cancer, diabetes, and immune system diseases. |
SciQ | SciQ-3928 | cell-biology, hematology, red-blood-cell
Title: Why are red blood cells considered to be cells? Wikipedia states that a cell is
the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that can replicate independently.
It then goes on to state that
All cells (except red blood cells which lack a cell nucleus and most organelles to accommodate maximum space for hemoglobin) possess DNA.
Then why are red blood cells still considered cells, while they can't replicate? Is the definition on Wikipedia just a bad definition? Or are red blood cells wrongly considered cells, but remain so for historical reasons? Or are they considered cells for some other reason, such as this answer which states that red blood cells do contain a nucleus at some point? A very good question, and it is most likely because of the last option. It had a nucleus for part of its life. After the RBC jettisons its nucleus, it still remains very metabolically active for approximately 3 months. It maintains its cell membrane integrity, it metabolizes glucose, it interacts constantly with its environment, numerous cellular functions and structure remain intact... It is extremely specialized for a primary purpose, and no longer requires the nucleus to provide more proteins. It has limited capacity to heal from injury, so it has a limited life span.
Speculation: I wonder if it might lose the nucleus early on so that when it is destroyed in the spleen at the end of its life as RBCs are, the spleen macrophages are not overwhelmed with additional processing of nucleic acids? Macrophage type cells are already working hard in there to clear infectious agents and some immune cells from the blood.
The following is multiple choice question (with options) to answer.
Red bone marrow, tonsils, spleen, and thymus gland are considered organs of what system? | [
"endocrine",
"nervous",
"circulatory",
"lymphatic"
] | D | The lymph organs are the red bone marrow , tonsils , spleen , and thymus gland . They are described below ( Figure below ). |
SciQ | SciQ-3929 | electrostatics
Title: Inducing positive charge on a Sphere(Metallic) Sorry if this question is asked already. I want to know that while inducing positive charge on a neutral body, at the time of earthing why the electrons move out so easily from the neutral body to the ground.I wonder Is it that easy to remove the electrons from a body. And aren't there a lots of electrons already in the ground so that if electrons are moving through earthing to ground will be repelled back to the body. Hope I will get a reply soon Thanks! The potential of earth is consider to be zero so charge can easily flow into earth as charge flow from body at higher potential to lower potential.Also the earth is so large that the addition of electrons dont increase the charge of earth they will simply lost in the earth.
The following is multiple choice question (with options) to answer.
What is it called when you touch a charged object to the earth? | [
"charging",
"grounding",
"dispersion",
"cooling"
] | B | The earth is also a conductor. Touching a charged object to the earth is called grounding . When you touch a conductor to the earth, you allow the earth to share the charge. Since the earth is billions of times bigger than the object, the earth takes nearly all of the charge. The charged object that was grounded now has zero charge. |
SciQ | SciQ-3930 | tissue
Title: What are the main differences between lab-grown tissues and natural tissues from living animals? What are the main differences between lab-grown tissues and natural tissues from living animals?
Using a biologist's classic "structure (anatomy) and function (physiology)" idea, I thought about the followings:
Structure:
It might be difficult to recreate the composition of different tissues / cells in living things precisely with artificial methods. This may lead to bad results when the tissue is used for tests of medicines and cosmetics.
Function:
Cells might not function and produce as expected (or is harder to make them function) in artificial compositions, as cells need strictly regulated environments to function correctly.
The following is multiple choice question (with options) to answer.
What is the basic unit of structure and function of living things? | [
"particle",
"cell",
"atom",
"molecule"
] | B | All forms of life are built of cells. A cell is the basic unit of the structure and function of living things. |
SciQ | SciQ-3931 | botany, plant-physiology, ecology, virology, host-pathogen-interaction
Note about symbiosis - comes in reaction to @Gerhard's comment
Different authors use the word symbiosis differently. From wikipedia:
The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).4 After 130+ years of debate,5 current biology and ecology textbooks now use the latter "de Bary" definition or an even broader definition (i.e. symbiosis = all species interactions), with the restrictive definition no longer used (i.e. symbiosis = mutualism)
The following is multiple choice question (with options) to answer.
What are the three types of symbiotic relationships? | [
"pledgism, truism, greenism",
"mutualism, communalism, parasitism",
"symbiosis , communalism , parasitism",
"altruism, conservatism, communalism"
] | B | Symbiosis describes a close and long-term relationship between different species. At least one species will benefit in a symbiotic relationship. These relationships are often necessary for the survival of one or both organisms. There are three types of symbiotic relationships: mutualism, communalism, and parasitism. |
SciQ | SciQ-3932 | cell-biology, terminology
Title: What is the difference between cytosol and cytoplasm? I've generally seen cytosol defined as the solution inside cells minus the organelles, cytoskeleton, etc and cytoplasm as the cytosol plus the organelles, cytoskeleton, etc. This naturally leads to the impression that cytosol is the cytoplasm minus all the solids. The problem here is that there are all sorts of other large molecules in the cells which could be thought of as solid. Are they also part of the cytosol or are they suspended in it? (I.e. are they part of the cytosol or are they non-cytosol components of the cytoplasm?)
Basically, I'm asking if the precise definition of cytosol is just anything in the cell that's not behind an endomembrane (save the exoskeleton) or if the dividing line is something else.
Subquestion: things can get even more terminologically confused because the cytosol is sometimes called the matrix. What the heck is the preferred terminology with this stuff? IMO, the definitive answer to this question is given in a paper by J. S Clegg. He traced the origin of the term cytosol to a book chapter by H. A. Lardy, and confirmed by email that Lardy had indeed coined the term. Their definition of cytosol is as follows:
... that portion of the cell which is found in the supernatant fraction after centrifuging the homogenate at 105 000 x g for 1 hour.
The following is multiple choice question (with options) to answer.
What is the name of the major components of cell membranes called? | [
"phospholipids",
"eukaryotes",
"cytoplasm",
"antibodies"
] | A | Phospholipids are the major components of cell membranes. |
SciQ | SciQ-3933 | respiration, pathophysiology, homeostasis, ph, anaerobic-respiration
Fig. 1. Schematic showing the excititoxic effects of excess glutamate in the brain. Source: Neuropathology.
References
- Choi, J Neurobiol (1992); 23(9): 1261-76
- Schur & Rigor, Dev Neurosci (1998); 20: 348-357
The following is multiple choice question (with options) to answer.
What organ breaks down excess amino acids and toxins in the blood? | [
"liver",
"kidney",
"heart",
"lungs"
] | A | Salamanders can breathe with the help of gills, lungs, or their skin surface. |
SciQ | SciQ-3934 | optics, visible-light, wavelength
Title: Why we can't see objects smaller than wave length of light? I would like to ask, why we can't see objects smaller than wave length of light under traditional microscope. I know that there is some way to see them and the scientists who discover this.
Why we can't see objects smaller than wave length of light?
And who were these scientists?
I would like to ask, why we can't see objects smaller than wave length of light under traditional microscope.
The wavelength of light is any wavelength. There's visible light (which is what I think you mean) and then there's every possible wavelength above and below that.
Our eyes don't detect light (electromagnetic radiation) outside of the visible region (hence the name :-)) but we can use and do machines to detect these wavelengths and you've probably experienced them : X-ray machines, UV lights for security purpose, infra-red lights for remote controls.
Whatever wavelength you use is going to diffraction limited for resolution. As this detailed article explains, the limit for resolution (and that's assuming everything else is optimal) is about half the wavelength used.
Optical microscopes are designed for the visible wavelengths of light and focus light outside of this region well. You can use special optics designed for that purpose if your interest is outside of visible light.
The development and use of microscopes, not just visible light microscopes, is called Microscopy. That link should provide you with enough information to start with.
I know that there is some way to see them and the scientists who discover this.
Beyond light microscopes, scientists developed the electron microscope and later the scanning tunneling microscope. The principles of these devices are explained at those links.
The 1986 Nobel prize for Physics was shared between three people for their work on these inventions. Another man, Hans Busch, had made a major contribution to the design of the electron microscope but died in 1984 and the Nobel Prize is never awarded posthumously, so even if the committee had thought it appropriate to award him, the rules would have forbidden it.
The following is multiple choice question (with options) to answer.
What do wavelengths measure the size of? | [
"fossils",
"tides",
"winds",
"waves"
] | D | Wavelength is one way of measuring the size of waves. It is the distance between two corresponding points on adjacent waves, and it is usually measured in meters. How it is measured is a little different for transverse and longitudinal waves. |
SciQ | SciQ-3935 | volcanology, geomorphology
Title: Why doesn't the whole volcanic cone appear black? Cooled lava looks black, but why the whole volcano, even near crater, doesn't always appear black like cooled lava? The cooled lava might be covered by ashes. So depending of the amount of ashes and the wind you might have a black volcano or a gray volcano. Many volcanoes are formed by layers of lava and ash.
https://en.wikipedia.org/wiki/Volcano#/media/File:Volcano_scheme.svg
The following is multiple choice question (with options) to answer.
Lava flows from a volcano and hardens into what? | [
"snow",
"rock",
"sand",
"life"
] | B | lava flows from a volcano and hardens into rock. |
SciQ | SciQ-3936 | dna, chromosome
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
But Why does DNA need to be coiled tightly into chromosomes?
DNA double helix is like a telephone wire. If length is to be measured, it will go beyond 60 miles. Some even say it can make a trip to the moon more than 150,000 times. Such a long DNA molecule is not only the part of each organism's cell nucleus but also it's invisible to the naked eye. This happens just because of the high packaging and coiling of this long DNA molecule.
Let's see the diagram to get an idea.
At the bottom of the diagram there is a sequence of nucleotides (ATGC) in different combinations. This can be considered as a gene if it codes for certain protein which is required for the growth or any other function of the body.
Returning back to your question, Complimentary base pairs are not genes.
Genes are the segments of DNA which is a long sequence of nucleotide base pairs that code for any protein or RNA transcript that contributes to any trait/phenotype/function of an individual.
With the tight packaging of DNA double helix along with help of packaging proteins(Histones and Non-histones), the chromatid and chromosomes are made. The packaging of DNA to chromosomes is highly controlled and is a whole different topic in itself.
The following is multiple choice question (with options) to answer.
What is the term for coiled structures made of dna and proteins? | [
"chromosomes",
"neutrons",
"nodes",
"platelets"
] | A | Chromosomes are coiled structures made of DNA and proteins. Chromosomes are the form of the genetic material of a cell during cell division. During other phases of the cell cycle, DNA is not coiled into chromosomes. Instead, it exists as a grainy material called chromatin . |
SciQ | SciQ-3937 | bacteriology, soil, nitrogen-cycle
While nitrite is the main product, the enzyme from N. europaea can produce nitric oxide as well. Therefore Step 2 can produce nitric oxide (NO). In this case, additional mechanisms of converting NO to NO2 are involved.
Further destiny of released nitrite can be different. In one process it could be oxidized by different microorganisms (bacteria, archaea) to nitrate (NO3) which could be consumed by plants or washed out to deeper horizons with water. In another case, nitrite, nitric oxide and nitrate could be involved in process of denitrification. During this process, a group of denitrifying organisms (bacteria, archaea and fungi) consume nitrogenous compounds and reduce them to nitrogen (N2), which can escape to the atmosphere. This process can occur through different metabolic pathways mainly with aid of reductases like nitric oxide reductase. One of the possible intermediate product of such pathways is a nitrous oxide (NO2). If N2O escapes from cells we can observe a resale of nitrous oxide from soil.
Let's return to your first question, and particularly to the part where you ask about significant amounts of nitrous oxide.
First of all, nitrification is a natural process and is a part of the nitrogen cycle. Some organisms fixate nitrogen and convert it to ammonia, some oxidize ammonia to nitrous compounds and some of them reduce it back to nitrogen. It occurs everywhere virtually in all terrestrial and water biocenoses. In a healthy ecosystem, the inflow of nitrogen is theoretically equal to the outflow (with temporal deposition in trophic chains). In such natural conditions, the release of nitrous oxide should be neglectable.
The situation changes significantly when we add an ammonia to soil artificially as a fertilizer. The main problem is that we break an equilibrium between nitrogen fixation, nitrification and denitrification. The second big problem is that an ammonia is toxic for most organisms, so we can alter microbiome. In such case, we can expect an excess of products of nitrification and improper denitrification with exaggerated levels of released nitrous oxide. The actual proportions vary significantly depending on both biotic and abiotic conditions, therefore it is difficult to predict real levels of nitrous oxide released without in situ examination.
The following is multiple choice question (with options) to answer.
Archaeans produce what kind of gas as a waste product? | [
"methane",
"carbon dioxide",
"sulfide",
"carbon monoxide"
] | A | Many archaeans live in close relationships with other organisms. For example, large numbers live inside animals, including humans. Unlike many bacteria, archaeans don't harm their hosts. None of them is known to cause human disease. Archaeans are more likely to help their hosts. For example, archaeans called methanogens live inside the gut of cows (see Figure below ). They help cows digest tough plant fibers made of cellulose. They produce methane gas as a waste product. |
SciQ | SciQ-3938 | mole, mixtures
By definition, mole fraction of $i$-th component in the mixture is
$$x_i = \frac{n_i}{\sum_j n_j} = \frac{m_i}{M_i\sum_j\frac{m_j}{M_j}} = \frac{ω_im}{M_i\sum_j\frac{ω_jm}{M_j}} = \frac{ω_i}{M_i\sum_j\frac{ω_j}{M_j}}.\tag{2.1}$$
Plugging in the corresponding quantities:
$$x_1 = \frac{0.30}{\pu{2.0 g mol-1} × \left(\frac{0.30}{\pu{2.0 g mol-1}} + \frac{0.35}{\pu{28 g mol-1}} + \frac{0.35}{\pu{44 g mol-1}}\right)} = 0.88 \tag{2.2.1};$$
$$x_2 = \frac{0.35}{\pu{28 g mol-1} × \left(\frac{0.30}{\pu{2.0 g mol-1}} + \frac{0.35}{\pu{28 g mol-1}} + \frac{0.35}{\pu{44 g mol-1}}\right)} = 0.07 \tag{2.2.2};$$
$$x_3 = \frac{0.35}{\pu{44 g mol-1} × \left(\frac{0.30}{\pu{2.0 g mol-1}} + \frac{0.35}{\pu{28 g mol-1}} + \frac{0.35}{\pu{44 g mol-1}}\right)} = 0.05 \tag{2.2.3}.$$
The following is multiple choice question (with options) to answer.
The mole fraction of the solvent is just one minus the mole fraction of what? | [
"molecules",
"nutrients",
"solution",
"solute"
] | D | The molarity is 0.0129 M, the molality is 0.0129 m, the mole fraction is 2.33 × 10 , and the solution contains 1830 ppm Na2HPO4. Mole fraction is most useful for calculating vapor pressure, because Raoult’s law states that the vapor pressure of a solution containing a non-volatile solute is equal to the mole fraction of solvent times the vapor pressure of the pure solvent. The mole fraction of the solvent is just one minus the mole fraction of solute. |
SciQ | SciQ-3939 | electromagnetism, thermodynamics, energy, work, radiation
Title: Is energy only transmitted through electromagnetic and particle radiations? Which are the other ways of transmission if any? If energy does not require any medium for transmission(as for sunlight reaching earth, the heat too), is it transmitted in quanta in particle radiation too? Energy transfer can be thought to occur via the exchange of a 'virtual particle'. In nature, there are 4 fundamental forces, namely:
1. Electromagnetic force
2. Gravitational force
3. Strong force
4. Weak force
Each of these forces have a different exchange particle:
For instance, the exchange particle for EM is a photon whereas that for the strong force is the gluon. The nature of the interaction is characterised by the properties of the exchange particle.
Now if you want to connect this rather abstract idea to a bigger picture of the more 'real world', you just have to carefully think about what the process you are considering actually involved on a deeper level.
For example: suppose you are pushing a box across your room. What you are actually doing is repelling the electrons on the box by the electrons on your hands, thus causing it to move. Therefore, you the interaction is an electromagnetic interaction and hence the exchange particles involved are photons.
If you think of energy transfer in this way, then indeed all energy transfers occur via 'particle exchanges' or radiation (since you a particle is essentially a wave packet [wave particle duality]).
The following is multiple choice question (with options) to answer.
Electromagnetic specturm is the full spectrum of raidant energy, which is energy emitted and transmitted as what? | [
"waves",
"tides",
"currents",
"flows"
] | A | The noble gases are characterized by their high ionization energies and low electron affinities. |
SciQ | SciQ-3940 | cell-biology
Title: Structure of Cell Are cells spheres or ovals/circles bound by phospholipidbilayer?
If they are spherical how are we able to see the nucleus through the phospholipid bilayer under a microscope? Not exactly. That is a stereotype of cells. Muscle cells are not round nor oval, but rather elongated rods. If you were to look up epithelia cells, you can quickly see that cells are grouped based on their physical characteristics; simple (round/oval & single layer), columnar, and cuboidal to name a few. Cells come in many shapes and sizes. As Hans stated, stains are vital in viewing cellular components. There is a diverse amount of stains used - which all carry a purpose and benefit in a specific application.
The following is multiple choice question (with options) to answer.
What structures formed of twisted actin chains are found in almost every cell, and are numerous in muscle cells and cells that move by changing shape? | [
"microfilaments",
"DNA",
"vesicles",
"RNA"
] | A | Microfilaments , shown in Figure below (b) , are made of two thin actin chains that are twisted around one another. Microfilaments are mostly concentrated just beneath the cell membrane, where they support the cell and help the cell keep its shape. Microfilaments form cytoplasmatic extensions, such as pseudopodia and microvilli, which allow certain cells to move. The actin of the microfilaments interacts with the protein myosin to cause contraction in muscle cells. Microfilaments are found in almost every cell, and are numerous in muscle cells and in cells that move by changing shape, such as phagocytes (white blood cells that search the body for bacteria and other invaders). |
SciQ | SciQ-3941 | cardiology, fat-metabolism
Title: Can fats clog veins or capillaries? I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
I googled a bit but everything was regarding arteries.
Is it because veins have a much wider diameter than arteries that even if some fats deposit they won't clog it?
And for capillaries, they are much smaller so shouldn't they be more vulnerable to this?
In addition, I guess since one of the lymphatic vessels functions are to transport fats from capillaries in villi to bloodstream, how are they adapted to prevent deposit of fats as they carry out the transportation?
N:B I'm just an OL biology student, and also horrible at chemistry
I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
Wikipedia says this:
Veins do not develop atheromata, because they are not subjected to the same haemodynamic pressure that arteries are,[8] unless surgically moved to function as an artery, as in bypass surgery.
The cited study isn't freely available, but seems to have tested in rabbits by surgically modifying their blood flow and giving them a high fat diet.
As for capillaries, they are continuously remodeled, so while they do become clogged for a variety of reasons, once flow stops they're disassembled and new capillaries formed if the tissue becomes hypoxic.
The following is multiple choice question (with options) to answer.
What impact can plaque in an artery have on the flow of blood? | [
"no effect",
"allergic reaction",
"increased flow",
"restriction"
] | D | Normally blood needs to flow freely through our arteries. Plaque in an artery can restrict the flow of blood. As you can probably imagine, this is not an ideal situation. And eating right, exercising, and not smoking can help keep your arteries healthy. |
SciQ | SciQ-3942 | electrons, charge, quasiparticles, leptons
Title: How do electrons get a charge? Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged?
The negative or positive charges were assigned by convention. But it is a fact that electrons are charged. My question is why electrons? and not neutrons?
Also while reading http://en.wikipedia.org/wiki/Electron, I saw that "Independent electrons moving in vacuum are termed free electrons. Electrons in metals also behave as if they were free. In reality the particles that are commonly termed electrons in metals and other solids are quasi electrons, quasiparticles, which have the same electrical charge, spin and magnetic moment as real electrons but may have a different mass ( or Effective mass - extra mass that a particle seems to have while interacting with some force )."
What does this mean? Your question touches the question of ontology in particle physics. Historically we are used to be thinking of particles as tiny independent entities that behave according to some laws of motion. This stems from the atomistic theory of matter, which was developed some two thousand years ago from the starting point of what would happen if we could split matter in ever smaller parts. The old Greeks came to the conclusion that there had to be a limit to that splitting, hence the atom hypothesis was born.
This was just a philosophical idea, of course, until around the beginning of the 19th century we learned to do chemistry so well that it became obvious that the smallest chunks that matter can be split into seemed to be the atoms of the periodic table. A hundred years later we realized that atoms can be split even further into nuclei and electrons. What didn't change was this idea that each chunk had its own independent existence.
This idea ran into a deep crisis during the early 20th century when we discovered the first effects of quantum mechanics. It turns out that atoms and nuclei and electrons do not, at all, behave like really small pieces of ordinary matter. Instead, they are behaving radically different, so different, indeed, that the human imagination has a hard time keeping up with their dynamic properties.
The following is multiple choice question (with options) to answer.
What type of charge do electrons have? | [
"negative",
"bipolar",
"positive",
"neutral"
] | A | Electrons have negative charge and protons have positive charge. The magnitude of the charge is the same for both, . |
SciQ | SciQ-3943 | transcription, translation
Ralston, A. (2008) Operons and prokaryotic gene regulation. Nature Education
From Genes to Genomes: Concepts and Applications of DNA Technology
Molecular cell biology
Analysis of Genes and Genomes
The following is multiple choice question (with options) to answer.
Which cells change the accessibility, transcription, or translation of a gene? | [
"prokaryotic",
"ribosomes",
"endogenous",
"eukaryotic"
] | D | that extends the 3' end, so a primer is synthesized and extended. Thus, the ends are protected. 16 The cell controls which protein is expressed, and to what level that protein is expressed, in the cell. Prokaryotic cells alter the transcription rate to turn genes on or off. This method will increase or decrease protein levels in response to what is needed by the cell. Eukaryotic cells change the accessibility (epigenetic), transcription, or translation of a gene. This will alter the amount of RNA, and the lifespan of the RNA, to alter the amount of protein that exists. Eukaryotic cells also change the protein’s translation to increase or decrease its overall levels. Eukaryotic organisms are much more complex and can manipulate protein levels by changing many stages in the process. |
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