source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-5444 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
What term means an area where two closely related species continue to interact and reproduce? | [
"common zone",
"homozone",
"hybrid zone",
"heterozone"
] | C | Reconnection After speciation, two species may recombine or even continue interacting indefinitely. Individual organisms will mate with any nearby individual who they are capable of breeding with. An area where two closely related species continue to interact and reproduce, forming hybrids, is called a hybrid zone. Over time, the hybrid zone may change depending on the fitness of the hybrids and the reproductive barriers (Figure 18.22). If the hybrids are less fit than the parents, reinforcement of speciation occurs, and the species continue to diverge until they can no longer mate and produce viable offspring. If reproductive barriers weaken, fusion occurs and the two species become one. Barriers remain the same if hybrids are fit and reproductive: stability may occur and hybridization continues. |
SciQ | SciQ-5445 | ecology, mycology
Title: Is there an antagonistic association between Penicillium and Aspergillus? Some Aspergillus species appear to like walnuts. My question concerns the association of Penicillium and Aspergillus. No sooner does Aspergillus colonize a walnut (or some other challenging carbon source) than Penicillium seems to move in, eventually killing the Aspergillus colony.
A totally unscientific guess is that Aspergillus is a good colonizer and Penicillium a good opportunist and that this is a common pattern with these two species. Is there any science in this direction? I do recall a sort of well-known picture from an old text in which Penicillium is shown more or less strangling a species of Aspergillus. I didn't think about it much at the time.
The image attached is not very incriminating but the theme is the same. Penicillium are the green hand-like structures strewn about the clover-like Aspergillus. Foot-cell of the latter cropped.
This seems like a simple question but a quick search doesn't reveal a lot, I think in part because this would generally come up as a contamination issue. It is hard to find any articles on the association between Penicillium and Aspergillus species, although they are both considered two of the most common mold species found indoors.
In this study, the most prevalent spore types detected in both the indoor and outdoor air samples were generally from the Penicillium/Aspergillus group [...] these findings are qualitatively similar to those observed in other geographical locations, confirming the ubiquitous nature of these fungi.
Although these genera seem to be found commonly, it also has to do with environmental factors, and the relative humidity of the area as well.
Geographical location, climate, and short-term meteorological
conditions are responsible for outdoor types and levels of fungal
spores.
As for the association and apparently colonization/opportunistic behaviour of the genera, it seems like there are not any associations between the two, unless perhaps environmental conditions are subject to changing, and different mold species have different moisture/temperature thresholds, although again these mold groups tend to be generalists and do well at a wider range of environmental conditions than other fungi.
The following is multiple choice question (with options) to answer.
Fungi may have both asexual and sexual stages of what? | [
"photosynthesis",
"absorption",
"reproduction",
"development"
] | C | Figure 24.8 Fungi may have both asexual and sexual stages of reproduction. |
SciQ | SciQ-5446 | geophysics, hydrology, geysers
Are the 65 minute and 91 minute values given for the eruption times simply a byproduct of needing more time for the steam to "recharge" after a larger eruption, or is there a deeper interplay between the underground cavity and the main channel that causes some sort of a vortex that has a (somewhat) regular periodicity? First I would like to say this is not my area of expertise, so this should perhaps be a comment but I am not allowed yet to comment on this site.
In a simplistic view a geyser has heated water chamber with a column of water above it. The water is heated above the normal boiling temperature but is kept liquid by the pressure of the water column above it. When the water eventually starts to vaporize this reduces the pressure on the water in the chamber resulting in more rapid vaporization of the water in the chamber resulting in the eruption.
For Old Faithful assume two chambers, one chamber is lower than the other. If the temperatures in both chambers are high enough the vaporization in the upper chamber would also reduce the pressure in the lower chamber allowing it to vaporize resulting in both chambers emptying, resulting in a longer eruption. Assuming the infill and heating rates are essentially constant then the time before the next eruption would take longer because both chambers are "empty". On the other hand if the upper chamber vaporizes and but the lower one does not, either because it is not hot enough or the pressure hasn't dropped enough or back pressure from the upper chamber keeps the lower chamber liquid, then only the upper chamber will empty resulting in less time to infill and reheat.
Again not my area.
The following is multiple choice question (with options) to answer.
Geysers erupt because what boiling hot substance is trapped beneath their surface? | [
"lava",
"gas",
"water",
"oil"
] | C | Geysers erupt because the water is trapped. The water becomes superheated until finally the pressure builds enough for it to break the seal. |
SciQ | SciQ-5447 | neuroscience, brain, neurophysiology
Title: What are Intersensory Associations? While I was reading about "Neural Control and Coordination" I came across this
"Association areas in the forebrain are responsible for complex functions like intersensory associations, ....."
What are "intersensory associations"? I have searched the net but could not find anything useful. A more common terminology regarding 'intersensory associations' is multisensory or crossmodal integration. Crossmodal integration takes place in the association cortices in the brain (Fig. 1). An example is the coupling of auditory and visual input during lip reading, as mentioned in the comments. Lip reading can aid in acoustic speech understanding, especially so in the hearing impaired.
The association cortices include most of the cerebral surface of the human brain and are responsible for integrating the sensory input that arrives in the primary sensory cortices. The diverse functions of the association cortices are loosely referred to as “cognition,” which literally means the process by which we come to know the world. Cognition enables us to attend to external stimuli, to identify the significance of stimuli and to plan meaningful responses to them. The association cortices receive and integrate information from a variety of sources and in turn influence a range of cortical and subcortical targets (Purves et al., 2001).
Fig. 1. Association cortices. source: Brown, Physiology & Neuroscience websites
Reference
- Purves et al., Neuroscience, 2nd ed. Sunderland (MA): Sinauer Associates; 2001
The following is multiple choice question (with options) to answer.
About one-third of the human cerebral cortex is dedicated to analyzing and perceiving information related to what sense? | [
"vision",
"taste",
"touch",
"hearing"
] | A | 36.5 | Vision By the end of this section, you will be able to: • Explain how electromagnetic waves differs from sound waves • Trace the path of light through the eye to the point of the optic nerve • Explain tonic activity as it is manifested in photoreceptors in the retina Vision is the ability to detect light patterns from the outside environment and interpret them into images. Animals are bombarded with sensory information, and the sheer volume of visual information can be problematic. Fortunately, the visual systems of species have evolved to attend to the most-important stimuli. The importance of vision to humans is further substantiated by the fact that about one-third of the human cerebral cortex is dedicated to analyzing and perceiving visual information. |
SciQ | SciQ-5448 | 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.
Fungus-like protists are what kind of feeders? | [
"refractive",
"absorptive",
"demonstrative",
"reverse"
] | B | Courtesy of H Weaver (JHU/APL), A Stern (SwRI), and the HST Pluto Companion Search Team. Pluto and its moon, Charon, are actually two objects . Public Domain. |
SciQ | SciQ-5449 | evolution, natural-selection, population-dynamics, adaptation
Title: Genetic Diversity and Adaptation I am somewhat new to evolutionary biology, having studied it on my free time as a computer science student. There is one particular thing that has always bothered me for which I have not seen a good treatment, relating to adaptations to the environment with respect to genetic diversity. If it is possible for a population to adapt to rapid environmental changes, and they don't have an adaptation for dealing with change directly (such as a complex brain), it seems to me that every generation must have present within them almost every possible environmental adaptation that the population is capable of expressing (including many irrelevant ones and a few relevant to the particular environmental challenge). Otherwise, it may take too many generations to deal with a change, which may be disastrous for the population.
So my question would be: how does an evolutionary biologist explain the mechanics behind the ability for a population to adapt quickly? Are most environmental changes slow or gradual enough that the population has a few generations to happen upon the mutations that will allow it to survive, and have generally been successful in this regard for 3.5 billion years? Or, are a large majority of possible adaptations present in almost every generation, and just serve no purpose or advantage for most of the population if the provided "benefit" is unneeded (i.e., are effectively neutral)? Or something in between? It is a good question. The question is hard to answer though because
The answer is not completely resolved
There are many influential parameters hidden behind this question.
Your question, as I understand it, can be formulated as
Do natural populations have enough genetic variance to directly respond to an environmental change or do they have to wait for this variance to be created through mutations?
To address this question, I will have to assume you have some intermediate level of knowledge in evolutionary biology.
How do we call these two alternatives?
Adaptation can occur through selection on:
Standing genetic variance
De novo mutations
How can we tell them apart?
This section is mainly inspired from Barrett and Schluter (2008).
Adaptation from standing genetic variance and from de novo mutations tend to yield different genetic signature.
In comparison to de novo mutations, adaptation from standing genetic variation is likely to lead to
Faster evolution
Because there the respond to the new environmental is immediate, there is no need to wait for more mutations.
Because the fitness variance associated with the trait under selection is very low even when the first mutation occurs.
Fixation of more alleles of small effects.
The following is multiple choice question (with options) to answer.
What is the process in which many new species evolve in a short period of time to fill available niches called? | [
"adaptive radiation",
"adaptation",
"spontaneous mutation",
"learned behavior"
] | A | After a mass extinction, many habitats are no longer inhabited by organisms because they have gone extinct. With new habitats available, some species will adapt to the new environments. Evolutionary processes act rapidly during these times. Many new species evolve to fill those available habitats. The process in which many new species evolve in a short period of time to fill available niches is called adaptive radiation . At the end of this period of rapid evolution, the life forms do not look much like the ones that were around before the mass extinction. One example came after the extinction of the dinosaurs. Mammals underwent adaptive radiation and became the dominant life form. Although they lived in the habitats the dinosaurs had lived in, they didn't look much like the dinosaurs. |
SciQ | SciQ-5450 | 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.
After fertilization, how many cells does a zygote form into? | [
"two",
"three",
"six",
"one"
] | A | After fertilization, the zygote divides to form two cells: the upper cell, or terminal cell, and the lower, or basal, cell. The division of the basal cell gives rise to the suspensor, which eventually makes connection with the maternal tissue. The suspensor provides a route for nutrition to be transported from the mother plant to the growing embryo. The terminal cell also divides, giving rise to a globular-shaped proembryo (Figure 32.19a). In dicots (eudicots), the developing embryo has a heart shape, due to the presence of the two rudimentary cotyledons (Figure 32.19b). In non-endospermic dicots, such as Capsella bursa, the endosperm develops initially, but is then digested, and the food reserves are moved into the two cotyledons. As the embryo and cotyledons enlarge, they run out of room inside the developing seed, and are forced to bend (Figure 32.19c). Ultimately, the embryo and cotyledons fill the seed (Figure 32.19d), and the seed is ready for dispersal. Embryonic development is suspended after some time, and growth is resumed only when the seed germinates. The developing seedling will rely on the food reserves stored in the cotyledons until the first set of leaves begin photosynthesis. |
SciQ | SciQ-5451 | reaction-mechanism, experimental-chemistry
Title: Why is ethanol not an oxidizer? I am attempting the 2016 Canadian Chemistry Contest Part A, and one of the questions concerns the WHMIS symbols and whether a compound is an oxidizer or not.
The correct answer is that ethanol would not require a WHMIS oxidizer symbol. However, I am confused as to why ethanol is not an oxidizer when compounds such as potassium permanganate and nitric acid are when all of them contain oxygen. For something to be an oxidiser. It must be capable of being reduced. The presence of oxygen is no particular indicator of the oxidising ability of a given species.
In potassium permanganate, manganese is in its +7 oxidation state (a very high oxidation state), consequently it is a good oxidant agent as it is able to gain electrons, causing oxidation of another species and itself being reduced.
In ethanol, there isn't the same possibility for reduction as the molecule is already in its lowest oxidation state. Even ethanal (an oxidation level up) isn't particularly oxidising (despite being able to accept electrons and become formally reduced).
The following is multiple choice question (with options) to answer.
Which common oxidizing agent can be used to oxidize alcohols? | [
"hydrogen chloride",
"hydrogen dichromate",
"potassium dichromate",
"potassium chloride"
] | C | Oxidation-reduction reactions are of central importance in organic chemistry and biochemistry. The burning of fuels that provides the energy to maintain our civilization and the metabolism of foods that furnish the energy that keeps us alive both involve redox reactions. All combustion reactions are also redox reactions. A typical combustion reaction is the burning of methane, the principal component of natural gas (Figure 5.5 "The Burning of Natural Gas"). CH4 + 2O2 → CO2 + 2H2O In respiration, the biochemical process by which the oxygen we inhale in air oxidizes foodstuffs to carbon dioxide and water, redox reactions provide energy to living cells. A typical respiratory reaction is the oxidation of glucose (C6H12O6), the simple sugar we encountered in the chapter-opening essay that makes up the diet of yeast: C6H12O6 + 6O2 → 6CO2 + 6H2O Organic chemists use a variety of redox reactions. For example, potassium dichromate (K2Cr2O7) is a common oxidizing agent that can be used to oxidize alcohols (symbolized. |
SciQ | SciQ-5452 | optics, visible-light, quantum-electrodynamics, reflection
Title: Is the glass made up of holes that let the light to go through it? The following passage has been extracted from the book "The Magic of Science-A.Frederick Collins" (1917):
Substances of all kinds
have pores or holes in them. A sponge has pores that can
be seen and so has cheese, be it
green or yellow; and so, too,
have glass and metals, but the
pores or holes in the latter are so
small that you couldn't see them
even with a high-powered microscope,
but in glass they are
large enough to let light go
through them and in metals they
are large enough to let electricity
flow through them.
The following passage has been extracted from the book "QED:The strage theory of light and matter-Richard P Feynman" (around 1983-1985):
There are several possible theories that you could make up to account for the partial reflection of light by glass. One of them is that 96% of the surface of the glass is "holes" that let the light through while the other 4% of the surface is covered by small "spots" of reflective material. Newton realized that this is not a possible explanation.
Aren't the two passages in contradiction with each other?
Frederick says that glass is made up of holes that facilitates the passage of light through it, on the other hand Feynman is not ready to come in agreement. I think Frederick is little sloppy. Isn't it? Today we know that Collins is wrong.
He appears to be unaware of Newton's finding, and of course, advances made after he wrote his book.
The following is multiple choice question (with options) to answer.
What are gemstones known as when light cannot pass through them? | [
"protective",
"inorganic",
"blocking",
"opaque"
] | D | Most gemstones are not used exactly as they are found in nature. Usually, gems are cut and polished. Figure below shows an uncut piece of ruby and a ruby that has been cut and polished. The way a mineral splits along a surface allows it to be cut to produce smooth surfaces. Notice that the cut and polished ruby sparkles more. Gems sparkle because light bounces back when it hits them. These gems are cut so that the most amount of light possible bounces back. Other gemstones, such as turquoise, are opaque, which means light does not pass through them. These gems are not cut in the same way. |
SciQ | SciQ-5453 | evolution, psychology, sociobiology
Title: Female preference for males who are already in a relationship A common saying is that women are generally more attracted towards men who are already in a relationship, and this phenomena does seem to have its own place in popular culture that is not matched by a corresponding male preference for women who are already in a relationship.
From an intuitive viewpoint I think it would make sense from the woman's viewpoint in an system of information economics where the fact that a male is engaged in a successful relationship with another female, or several other females, might provide extra and positive information about the evolutionary value of the male.
But how about the possibility for a male to use the same trick?
Is there any empirical evidence for this behaviour at all either in humans or in other species, or is this just a cultural artefact in some human societies? If there is empirical support, is there a consensus on the plausible evolutionary pathways involved here? This is a widely researched topic in the overlap between social sciences and evolutionary biology. Evolution has become very influential in understanding human interaction and preferences.
This chapter from "The Adapted Mind : Evolutionary Psychology and the Generation of Culture" will give you an idea of how all this plays out in the big picture - its a fairly comprehensive review of many factors considered in human mate choice. The study may be psychological, but the logic is derived from biology these days. (stackexchange won't let me link to google books - you can search for the title and look at chapter 6).
Evolutionary tendencies will favor more successful offspring. But for people it includes not only the genetic qualities of the mate (appearance, height, disease resistance, health) but also social qualities (how reliable or willing a mate is to support offspring).
First off you can see that there are many many factors which women take into consideration in their preferences. Its commonly said they are more complex than men, but that's another question. You have to take a range of factors holistically including the social environment.
I can't find this particular issue addressed in the literature, but I think that it might be attractive to women in some social settings. If there is a lot competition for 'quality' mates or resources for instance - if you have very few secure males or pessimistic females might create pressure which would cause females to prefer males which were successful.
The following is multiple choice question (with options) to answer.
In biology, a relationship that benefits both entities is known as what? | [
"predatory",
"altruism",
"mutualism",
"naturalism"
] | C | Some bacteria depend on other organisms for survival. For example, some bacteria live in the roots of legumes, such as pea plants ( Figure below ). The bacteria turn nitrogen-containing molecules into nitrogen that the plant can use. Meanwhile, the root provides nutrients to the bacteria. In this relationship, both the bacteria and the plant benefit, so it is known as a mutualism . |
SciQ | SciQ-5454 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
Some animals prepare for the long winters by storing food and going dormant, a behavior called what? | [
"hibernation",
"resting",
"pollination",
"gestation"
] | A | |
SciQ | SciQ-5455 | physical-chemistry, experimental-chemistry, reaction-control
Title: Why do some reactions need to be maintained at a particular temperature for prolonged periods of time? Some reactions require that temperatures of 70–100 °C to be maintained for periods of time as long as 24 hours. Why is this so? Quite simply, reactions happen faster at higher temperatures (because who likes waiting), and some may not proceed at all until heated. From a statistical viewpoint, you are giving more reactant molecules more energy, which thereby increases the number of collisions, which in turn increases the number of successful collisions (those which produce product). A typical way to attain such conditions is to place a reaction under reflux.
The following is multiple choice question (with options) to answer.
Biochemical reactions are optimal at physiological temperatures because many what lose function at lower and higher temperatures? | [
"carbohydrates",
"neurons",
"enzymes",
"hormones"
] | C | Biochemical reactions are optimal at physiological temperatures. For example, most biochemical reactions work best at the normal body temperature of 98.6˚F (37˚C). Many enzymes lose function at lower and higher temperatures. At higher temperatures, an enzyme’s shape deteriorates, and only when the temperature comes back to normal does the enzyme regain its shape and normal activity. |
SciQ | SciQ-5456 | species-identification, ornithology
Why would a mother do that to her young? Does she hates the little one? Not at all. It’s just that those little birds were made to fly, and they don’t know it, so she is going to push them out of the nest. She never lets them hit bottom, but she does let them fall, because they have to learn something they don’t know.
The next time the mother bird comes back she decides to clean house, and so she stands on the edge of the nest. The first things to go are the feathers inside; she drops them over the edge. Then the leaves go over the edge—heave ho! While this is going on, she’s not very talkative, either. ("Mom, what are you doing?") She pays no attention. Since she built the house, she knows how to take it apart.
Next she decides to take the sticks out of the middle of the nest, and with her great strong beak and feet, she’s able to break them off and stand them straight up. ("Mom, it’s not comfortable in here anymore.") Then she takes certain key sticks out of the nest and throws them over the edge. ("What are you doing, Mom? You are wrecking my room.")
She seemingly pays no attention to the concerns of her young as she prepares to pull the nest apart, for she is determined that those little ones will fly, and she knows something they don’t. She knows they will never fly as long as they remain in the nest.
The following is multiple choice question (with options) to answer.
What is the attachment of ducklings to their mother an example of? | [
"impressionism",
"validating",
"imprinting",
"magnetism"
] | C | Figure 45.39 The attachment of ducklings to their mother is an example of imprinting. (credit: modification of work by Mark Harkin). |
SciQ | SciQ-5457 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
All chordates are deuterostomes possessing a what? | [
"notochord",
"endoderm",
"hydrochord",
"zygote"
] | A | Figure 29.2 All chordates are deuterostomes possessing a notochord. |
SciQ | SciQ-5458 | 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.
In vascular plants, the sporophyte generation is what? | [
"dominant",
"evident",
"fast",
"submissive"
] | A | In vascular plants, the sporophyte generation is dominant. In seedless vascular plants such as ferns, the sporophyte releases spores from the undersides of leaves. The spores develop into tiny, separate gametophytes, from which the next generation of sporophyte plants grows. |
SciQ | SciQ-5459 | concentration
Title: Why would sodium ions want to go down just because of one side is more positive than the other? From Khan Academy starting from 1:25, the narrator, while talking about the Electrochemical gradients, said that sodium ions would naturally want to diffuse
down when having a high concentration up here and a low concentration down there.
My question is Why would sodium ions want to go down just because of one side is more positive than the other, I mean, isn't the same charges repelling each other? I don't think the degree of positivity will enable them to be attracted to each other.
Could anyone help me explain this? This has more to do with the diffusion gradient. Sodium ions move from the region of their higher concentration to a region of their lower concentration.
In the example given by you, I believe, there are additional negatively charged molecules present in the inner side of the membrane, resulting in an influx of sodium ions to balance the same. However, like charges do repel, so this influx is not indefinite, but only up to a certain extent- until the electrical potential difference across the membrane exactly balances the concentration gradient. This point is known as the equilibrium potential.
(This question and answer might be more appropriate in the Biology SE, I think).
The following is multiple choice question (with options) to answer.
The combined gradient that affects an ion includes its concentration gradient and its what? | [
"electron bond",
"radiation gradient",
"cell membrane",
"electrical gradient"
] | D | 5.3 Active Transport The combined gradient that affects an ion includes its concentration gradient and its electrical gradient. A positive ion, for example, might tend to diffuse into a new area, down its concentration gradient, but if it is diffusing into an area of net positive charge, its diffusion will be hampered by its electrical gradient. When dealing with ions in aqueous solutions, a combination of the electrochemical and concentration gradients, rather than just the concentration gradient alone, must be considered. Living cells need certain substances that exist inside the cell in concentrations greater than they exist in the extracellular space. Moving substances up their electrochemical gradients requires energy from the cell. Active transport uses energy stored in ATP to fuel this transport. Active transport of small molecular-sized materials uses integral proteins in the cell membrane to move the materials: These proteins are analogous to pumps. Some pumps, which carry out primary active transport, couple directly with ATP to drive their action. In co-transport (or secondary active transport), energy from primary transport can be used to move another substance into the cell and up its concentration gradient. |
SciQ | SciQ-5460 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
What is the first cell of a new organism? | [
"zygote",
"nucleus",
"seed",
"egg"
] | A | The new cell is stimulated with an electric shock and embryo development begins, as if it were a normal zygote . The zygote is the first cell of a new organism. |
SciQ | SciQ-5461 | photosynthesis, chloroplasts
Title: Chloroplasts in an animal cell What would happen if we inject a chloroplast organelle into an animal cell?
Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could there be photosynthesis in such a cell, or will some of the necessary mechanisms be missing? To answer your bigger question:
Yes, most of this is possible - under some conditions -, and animals and animal cells can acquire chloroplasts, and use them.
E.g.: see Elysia chlorotica whose cells actively take up chloroplasts and use them, and keep them alive (though not replicating). - Though some genes of algae are also contained in the Elysia chlorotica genome - which may be considered as partial replication.
Also there are salamanders that have replicating algae within them (since embryogenesis) - even algae (with chloroplasts) within animal cells - though here the algae might be rather understood as symbionts or "cell types", and the animal cells don't have the chloroplasts by themselves.
The following is multiple choice question (with options) to answer.
What part of the cell in plants and algae does photosynthesis take place? | [
"cell wall",
"mitochondria",
"fibers",
"organelles"
] | D | organelle in the cells of plants and algae where photosynthesis takes place. |
SciQ | SciQ-5462 | paleoclimatology
Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes. This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.
The following is multiple choice question (with options) to answer.
Exemplified by canada and alaska, what kind of climate has cool, short summers and long, cold winters, little precipitation, and abundant conifers? | [
"droughts climate",
"subarctic climate",
"temperate climate",
"tropical climate"
] | B | Subarctic climates are found between 60° and 70° north latitude. Much of Canada and Alaska have this type of climate. Summers are cool and short. Winters are very cold and long. Little precipitation falls, and most of it falls during the summer. Conifer forests grow in this climate ( Figure below ). |
SciQ | SciQ-5463 | 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.
What are the only organelles that prokaryotic cells have? | [
"fibroblasts",
"chloroplasts",
"nuclei",
"ribosomes"
] | D | Eukaryotic cells have other organelles besides the nucleus. The only organelles in a prokaryotic cell are ribosomes. |
SciQ | SciQ-5464 | solar-system, comets
Title: How does a comet form? As the title explains,
How does a comet form?
What are the elements, what is a comet composed of?
Why didn't they become part of planets, moons or asteroids?
Comets are some of the material left over from the formation of the planets. Our entire solar system, including comets, was created by the collapse of a giant, diffuse cloud of gas and dust about 4.6 billion years ago. Much of the matter merged into planets, but some remained to form small lumps of frozen gas and dust in the outer region of the solar system, where temperatures were cold enough to produce ice.
A comet is generally considered to consist of a small nucleus embedded in a nebulous disk called the coma. the nucleus, containing practically all the mass of the comet, is a “dirty snowball” conglomerate of ices and dust.For one, of the observed gases and meteoric particles that are ejected to provide the coma and tails of comets, most of the gases are fragmentary molecules, or radicals, of the most common elements in space: hydrogen, carbon, nitrogen, and oxygen. The radicals, for example, of CH, NH, and OH may be broken away from the stable molecules CH4 (methane), NH3 (ammonia), and H2O (water), which may exist as ices or more complex, very cold compounds in the nucleus.
3.Many astronomers believe that these small objects never became planets or other large objects because of the gravity of the large planets. For example, the pull of Jupiter's kept 'stirring the pot' of the asteroid belt, so that the gravitational pull of the asteroids on each other was constantly being disturbed.
For the Kuiper belt and Oort cloud, there is a popular theory called 'planetary migration.' The main idea behind this theory is that the large outer planets of our Solar System started out much closer to the Sun when the Solar System was formed. As they migrated outward through the cloud of small objects still there, the gravity of these large planets pulled a lot of the small objectsout of their orbits. Some were pulled into the planets, and some were flung far into the outer reaches of the Solar System.
The objects that were flung very far out by Jupiter became the Oort cloud. The object that were not flung out quite as far by the movement of Neptune became the Kuiper belt.
Source
The following is multiple choice question (with options) to answer.
What is the name of the cloud where most long-period comets come from? | [
"bulge cloud",
"volt cloud",
"oort cloud",
"stellar cloud"
] | C | Some comets have periods of thousands or even millions of years. Most long-period comets come from a very distant region of the solar system. This region is called the Oort cloud. The Oort cloud is about 50,000–100,000 times the distance from the Sun to Earth. |
SciQ | SciQ-5465 | “Stepping Stone” system. I implement the ecological model in an eco-evolutionary context with connected predator-prey adaptive radiations as emergent model outputs 20,34. x0(t) = a x(t) b x(t) y(t) y0(t) = c y(t) + d x(t) y(t) Now convert our model to a matrix - vector system. Parameter avlue Interpretation a 1. DYNAMICS OF A MODEL THREE SPECIES PREDATOR-PREY SYSTEM WITH CHOICE by Douglas Magomo A Dissertation Submitted to the Graduate Studies Office of The University of Southern Mississippi in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Approved: August 2007 Reproduced with permission of the copyright owner. Set the solver type to SSA to perform stochastic simulations, and set the stop time to 3. Detect events during solution of ODE. , how predators affect prey populations, and vice-versa. It is called the Lotka-Volterra model. For this model the fit is lower than previous because of the complexity of the model when the number of prey is assumed as finite; when the number of parameters increases, the estimation process becomes more complex. α = exponential growth in population – used for preys,. Matlab program to plot a phase portrait of the Lotka-Volterra Predator Prey model. The system considers the effects of anomalous diffusion and generalized Michaelis–Menten-type reactions. The quadratic cross term accounts for the interactions between the species. View Notes - lecture3b-predator from MAE m20 at University of California, Los Angeles. 17 Predator-Prey Models The logistic growth model (Chapter 11) focused on a single population. Predation rate is simulated using the Holling's "disc equation" of functional response:. Some examples of predator-prey relationships are lion-cape buffalo, tiger-deer, snake-frog, python-rabbit, bear-fish and cheetah-gazelle. In a team effort, we created a system of closed differential equations for a predator-prey model where we were then able to generate numerical simulations through MATLAB to visualize the data. The predator-dependent model is more suitable for prey predator interactions in which predation involves the search process. a discrete time predator prey model specified by Neubert et al[9] which utilises the Ricker model to simulate prey growth. Predator prey offers this graphic user interface
The following is multiple choice question (with options) to answer.
Different feeding "positions" in a food chain or web are associated with what kinds of levels? | [
"trophic",
"heptic",
"benthic",
"autotrophic"
] | A | The different feeding positions in a food chain or web are called trophic levels. |
SciQ | SciQ-5466 | bond, ions, ionic-compounds
Title: Why is the overall charge of an ionic compound zero?
My textbook simply says:
Since an ionic compound consists of equal number of positive and negative ions, the overall charge of an ionic compound is zero.
But why is the number of positive and negative ions equal?
Can’t an ionic compound can have an unequal number of negative and positive ions? Why or why not? Sodium needs to lose 1 Electron to attain stable electronic configuration and chlorine needs to gain 1 electron to stable electronic configuration.
In a big picture, the electron was transferred from sodium to chlorine in the same neutral crystal. No electron was supplied to the crystal from outside, it was already in the same system before and after the formation of NaCl.
If the system before formation of NaCl was neutral then it will be neutral even after the formation of NaCl crystal. That may be the reason.
The following is multiple choice question (with options) to answer.
Ionic compound atoms of various elements gain or lose electrons to? | [
"produce ions",
"expel ions",
"become ions",
"flatten ions"
] | A | So far we have looked at ionic compounds, in which atoms of various elements gain or lose electrons to produce ions. The resulting ions are held together by strong attractions between oppositely charged particles. However, this only works for bonds between atoms in which one partner (the metal) has a tendency to lose electrons, and the other (the nonmetal) has a tendency to gain them. Then how might two nonmetals, such as nitrogen and oxygen, form chemical bonds? Neither is likely to lose electrons and become a cation, but both require more electrons to reach a noble gas configuration. Instead of a complete transfer of electrons, these atoms can bond by sharing electrons, producing what is called a covalent bond . When a group of atoms are joined together by covalent bonds, the resulting structure is called a molecule . Molecules are generally much smaller than the extended three-dimensional networks of ions that are seen in ionic compounds. We will look much more at covalent bonding and molecules in future chapters, but for now, we will focus on the ways in which molecules are named. |
SciQ | SciQ-5467 | geology, sedimentology
Title: Is Desert Sandstone a chemical sedimentary rock? I gather that chemical sedimentary rocks are formed when minerals in solution are supersaturated and therefore they precipitate out.
I also understand that desert sandstone is formed as Iron Oxide rich water evaporates leaving a hematite cement.
Does this mean Desert Sandstone is a chemical sedimentary rocks? No, it's not.
The overwhelming majority of the material in the rock is clastic, not chemical. Chemical sedimentary rocks are rocks where (almost) all of the material was precipitated, such as travertine, evaporites, etc.
Cementation is a chemical process. As a clastic sedimentary rock has to be cemented somehow, otherwise it would be a sediment rather than a rock, all clastic sedimentary rocks have undergone some chemical process. This does not mean that they are chemical though.
As diagenesis progresses and the rock undergoes more chemical changes it may become a diagenetic clastic sedimentary rock of even a metamorphic one, but never a chemical sedimentary rock. This implies that most, if not all, of its initial mass precipitated out of solution.
The following is multiple choice question (with options) to answer.
Sedimentary rocks form in what kind of layers? | [
"vertical",
"magnetic",
"stacked",
"horizontal"
] | D | Sedimentary rocks are formed in horizontal layers. This is magnificently displayed around the southwestern United States. The arid climate allows rock layers to be well exposed ( Figure below ). The lowest layers are the oldest and the higher layers are younger. |
SciQ | SciQ-5468 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
Plants obtain the molecules for cellular function though what? | [
"Plants",
"tissues",
"nutrients",
"photosynthesis"
] | D | Introduction All living organisms need nutrients to survive. While plants can obtain the molecules required for cellular function through the process of photosynthesis, most animals obtain their nutrients by the consumption of other organisms. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. However, the food consumed consists of protein, fat, and complex carbohydrates. Animals must convert these macromolecules into the simple molecules required for maintaining cellular functions, such as assembling new molecules, cells, and tissues. The conversion of the food consumed to the nutrients required is a multi-step process involving digestion and absorption. During digestion, food particles are broken down to smaller components, and later, they are absorbed by the body. |
SciQ | SciQ-5469 | 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.
The group of plants that can make their own food from inorganic raw materials in the presence of sunlight are referred to as what? | [
"autosynonomys",
"symbiotic",
"heterotrophic",
"autotrophic"
] | D | Plants obtain food in two different ways. Autotrophic plants can make their own food from inorganic raw materials, such as carbon dioxide and water, through photosynthesis in the presence of sunlight. Green plants are included in this group. Some plants, however, are heterotrophic: they are totally parasitic and lacking in chlorophyll. These plants, referred to as holo-parasitic plants, are unable to synthesize organic carbon and draw all of their nutrients from the host plant. Plants may also enlist the help of microbial partners in nutrient acquisition. Particular species of bacteria and fungi have evolved along with certain plants to create a mutualistic symbiotic relationship with roots. This improves the nutrition of both the plant and the microbe. The formation of nodules in legume plants and mycorrhization can be considered among the nutritional adaptations of plants. However, these are not the only type of adaptations that we may find; many plants have other adaptations that allow them to thrive under specific conditions. |
SciQ | SciQ-5470 | human-biology, genetics, human-genetics
Title: Are all genetic disorders inherited? I know that genetic diseases such as cystic fibrosis are often passed down through generations and are therefore classified as genetic disorders, but if a mutation occurs spontaneously, which for example leads to cancer, is this then classified as a genetic disorder?
Are all genetic disorders inherited?
Not all individuals with a genetic disorder inherited that disorder. Some genetic disorders are caused by spontaneous mutations.
Is cancer a genetic disorder?
Yes. The seminal paper by Hanahan and Weinberg, the Hallmarks of Cancer, is a good place to go to get a sense of what we understand cancer to be. This paper is quite influential and has its own wikipedia page. These authors wrote an updated review in 2011. Re: your question as it relates to cancer, yes, genetic changes result in tumorigenesis. Cancer is a genetic disorder of cell populations. One can view cancer diagnosis and treatment from the framework of cancer as a metabolic disease, but this adds to, rather than subtracts from the framework of cancer as a genetic disease.
Are other diseases caused by spontaneous mutations genetic disorders?
Yes. Achondrodysplasia is one illuminating example. It is a form of dwarfism caused by a mutation in the FGFR3 gene. It does follow mendelian autosomal dominant inheritance patterns, but in 80% of cases, the mutation is, in fact, acquired spontaneously (that is, not present in either parent). As noted by @Eff in the comments, Down syndrome, Trisomy 21 (and other chromosomal abnormalities, e.g., Turner, Kleinfelter, Patau, Edwards) are other common examples.
The following is multiple choice question (with options) to answer.
What type of disorders are caused by mutations in genes or abnormal numbers of chromosomes? | [
"immune system disorders",
"emotional disorders",
"thyroid disorders",
"genetic disorders"
] | D | Many genetic disorders are caused by mutations in one or a few genes. Other genetic disorders are caused by abnormal numbers of chromosomes. |
SciQ | SciQ-5471 | Your are trying to understand important instructions from someone who is soft-spoken. From your distance $r_1$ her voice sounds like an average whisper of $20\, {\rm dB}$. So you move to a position where you are a distance $r_2$ from her and the sound level is at $60\, {\rm dB}$.
(a) If the intensity is $I_1$ at distance $r_1$ and $I_2$ at distance $r_2$, calculate the ratio $I_2/I_1$.
(b) Use your answer to part (a) to calculate the ratio $r_2/r_1$.
(a) The intensity level ($\beta$) of the sound waves is measured in ${\rm dB}$ by the following equation
$\beta=10\,{\log \frac{I}{I_0}\ }$
Where $I$ is the intensity of the source of sound at distance $r$ and $I_0$ is the hearing threshold. So find the ratio $I_2/I_1$ as follows
$\beta_1=10\,{\log \frac{I_1}{I_0}\ }\Rightarrow 20=10\,{\log \frac{I_1}{I_0}\ }\Rightarrow \frac{I_1}{I_0}={10}^2$
$\beta_2=10\,{\log \frac{I_2}{I_0}\ }\Rightarrow 60=10\,{\log \frac{I_2}{I_0}\ }\Rightarrow \frac{I_2}{I_0}={10}^6$
We have used the definition of the logarithm i.e. $y={\log x\ }\Rightarrow x={10}^y$. Dividing the two relation, we obtain
$\frac{I_2}{I_1}=\frac{{10}^6}{{10}^2}={10}^4$
The following is multiple choice question (with options) to answer.
What is the measure of sound intensity levels? | [
"octaves",
"centimeters",
"decibels",
"moles"
] | C | Sound intensity levels are quoted in decibels (dB) much more often than sound intensities in watts per meter squared. Decibels are the unit of choice in the scientific literature as well as in the popular media. The reasons for this choice of units are related to how we perceive sounds. How our ears perceive sound can be more accurately described by the logarithm of the intensity rather than directly to the intensity. The sound intensity level β in decibels of a sound having an intensity I in watts per meter squared is defined to be. |
SciQ | SciQ-5472 | thermodynamics, solid-state-physics
Title: "Freeze out" degrees of freedom (Specific heat) I am reading about Einstein's specific heat model for solids where author says that:
However, at low temperature the degrees of freedom “freeze out”, the system gets stuck in only the ground state eigenstate, and the heat capacity vanishes rapidly.
I suppose that at lower temperatures atoms don't have enough energy for example to rotate, but can't explain why. The thermal energy for each degree of freedom is given by
$$\frac{1}{2} k_{B} T $$
If this thermal energy is lower than the gap between ground state and first excited state (supposing quantised energy levels) then a thermal excitation becomes very unlikely. I would guess that this is what the author means by "frozen" degrees of freedom.
For a more precise answer it would help if you would give the reference of your quote.
The following is multiple choice question (with options) to answer.
What is the temperature at which a substance freezes known as? | [
"drop point",
"absolute zero",
"freezing point",
"zero point"
] | C | The freezing point of a substance is the temperature at which it freezes. The freezing point of pure water is 0°C. |
SciQ | SciQ-5473 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
Blood from what organs enters the left atrium of the heart? | [
"lungs",
"Brain",
"Lymph nodes",
"intestines"
] | A | Blood from the lungs enters the left atrium of the heart. The left atrium pumps the blood to the left ventricle, which pumps it to the body. |
SciQ | SciQ-5474 | the-sun, solar-system, earth, temperature, weather
That Wikipedia quote mentioned that "change in day length is another factor". I have some info and graphs about that here.
The distance from the Earth to the Sun does have an effect on the climate, but it's fairly minor. Currently, the Earth is closest to the Sun (perihelion) in early January, around 10 days after the December solstice, during the northern hemisphere winter and southern hemisphere summer. That makes the southern summer a bit hotter than the northern summer. It also makes the southern summer a bit shorter, because the orbital speed is fastest near the perihelion. However, the climate in the southern hemisphere is strongly affected by the strong circumpolar ocean current around Antarctica, which keeps the southern oceans cold all year round. In the southern hemisphere, not many people live at higher latitudes than 40° because it's just too cold, but that latitude in the northern hemisphere is quite heavily populated.
I have some info about the perihelion here and here.
For what it's worth, here's a graph of the distance from the Earth to Sun and to the SSB, for 2022, with a 7 day timestep between the data points.
Plotting script from https://astronomy.stackexchange.com/a/49823/16685
Here's a plot spanning 1700 to 2200 (the same timespan as my Sun-SSB plot in the answer linked above), also with a 7 day timestep.
The following is multiple choice question (with options) to answer.
The farther an area is from the equator, what happens to the temperature? | [
"it stabilizes",
"it increases",
"it fluctuates",
"it gets lower"
] | D | At higher latitudes, the Sun’s rays are less direct. The farther an area is from the Equator, the lower its temperature. |
SciQ | SciQ-5475 | human-biology, microbiology, literature
90% of these specimens were deemed "No Growth" by the standard urine culture technique, highlighting its limitations.
The last phrase "highlighting its limitations" is an interesting one. It appears to me to be yet to be proven that this is a clinically meaningful "limitation" of such assays. Without attempting to refute these data — fortunately this question doesn't require me to do so — I will note that the two linked studies aimed to show that people with overactive bladder are characterized by increased urinary flora. The explicitly stated hypothesis is that this may contribute to symptoms. Even in this study demonstrating the existence of such a micro-biome even in normal people, then, it is understood as a potentially pathologic state.
The reason this "mantra persists", then, is that it remains true for clinical purposes. In contrast to most (all?) other bodily discharges, urine is not packed with bacteria, and the commonly used assays reflect this fact. Medicine and laboratory science have different "modes of discourse", each calibrated to convey levels of precision that are appropriate to the outcomes of interest.
Notes
1. In American English at least, that adverb is ambiguous, meaning either "for practical purposes" or (idiomatically) "almost". Both senses are intended here.
2. Of course, there are plenty of data in various populations demonstrating that some substantial minority of urinalyses among asymptomatic people return positive, "proving" that we shouldn't be checking them (amen!). But this is not the point. The gestalt remains: normal = negative.
3. The nitrite parameter in particular is not especially sensitive. It is, however, quite specific (92-100%), meaning it reliably returns negative in people without infection. (See review, below.) Of course, negative nitrites does not mean sterile in the sense that the OP has used it; see "modes of discourse", above.
Reference
Simerville JA, et al. Urinalysis: A Comprehensive Review. Am Fam Physician. 2005 Mar;71(6):1153-1162.
The following is multiple choice question (with options) to answer.
What sort of issues can be determined by looking for certain particles in amniotic fluid? | [
"organic disorders",
"artificial disorders",
"genetic disorders",
"impossible disorders"
] | C | |
SciQ | SciQ-5476 | the-moon, astrophysics, orbital-mechanics
The Giant Impact hypothesis for lunar formation predicts that the moon formed close to the Earth in the equatorial plane. The effects of tides caused the Moon to slowly migrate outwards, through the transition region and into its current orbit. The current ~5° inclination of the Moon relative to the Laplace plane is likely a legacy of inclination excitation during the transition. Here's a video of a simulation of the transition by Sarah Stewart-Mukhopadhyay.
The following is multiple choice question (with options) to answer.
The lunar landscape is covered by craters caused by what? | [
"volcanoes",
"earth impacts",
"water",
"asteroid impacts"
] | D | The landscape of the Moon - its surface features - is very different from Earth. The lunar landscape is covered by craters caused by asteroid impacts ( Figure below ). The craters are bowl-shaped basins on the Moon’s surface. Because the Moon has no water, wind, or weather, the craters remain unchanged. |
SciQ | SciQ-5477 | the-sun, observational-astronomy
The green line is the meridian, the orange(ish) lines are alt/az coordiantes, the blue line is the celestial equator, and the red line is the path of the ecliptic. Hopefully you can make this out sufficiently well.
The following is multiple choice question (with options) to answer.
What is the name for the line dividing the earth's hemispheres? | [
"plate",
"longitude",
"equator",
"latitude"
] | C | |
SciQ | SciQ-5478 | waves, acoustics
Title: Sound pitch: why the louder the higher? I have been wondering for years why, listening to any music (or simply to a single tone), better with headphones/earphones, if the volume is very low (almost inaudible: 20-30 dB SPL), each audible note of the same music sounds flatter than when played at a far higher volume (70-80 dB SPL), using the same equipment: I guess about 20 cents sharper, when far louder. It is like a "static" Doppler effect depending on loudness and not motion, but I am surely talking nonsense. Please, consider that I am absolutely ignorant of Physics, although I am a musician! Thanks for your help. The perceived pitch of tones with a high frequency (above about 2 kHz) tends to increase when their sound pressure level is increased. This is a known psychoacoustic effect that agrees with your description. However, the perceived pitch of tones with a low frequency (e.g., 200 Hz) tends rather to decrease when their sound pressure level is increased. This appears to be due to an imperfect compensation for the more substantial effect an increased sound level has on the neural excitation pattern along the basilar membrane of the ear. The effect varies to some extent between listeners.
The following is multiple choice question (with options) to answer.
Dependent on the frequency of sound waves, what term described how high or low a sound seems to a listener? | [
"pitch",
"wavelength",
"curve",
"direction"
] | A | How high or low a sound seems to a listener is its pitch . Pitch, in turn, depends on the frequency of sound waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. High-pitched sounds, like the sounds of the piccolo in the Figure below , have high-frequency waves. Low-pitched sounds, like the sounds of the tuba Figure below , have low-frequency waves. For a video demonstration of frequency and pitch, go to this URL: http://www. youtube. com/watch?v=irqfGYD2UKw. |
SciQ | SciQ-5479 | energy, photons, semiconductor-physics, solar-cells
In down-conversion one high energy photon promotes an electron from 1 to 3, and by falling to energy level 2 and then 1, two photons can be emitted. Thus one high energy photon in and two low energy photons out.
Of course the next step would be to use a solar cell to collect the converted photons. The up and down converters themselves don't generate power.
Other approaches
There are other approaches to reaching higher efficiency. In specially engineered materials high energy photons can generate multiple electron-hole pairs which provides more current per photon than normal solar cells.
Then there are the hot-carrier approaches. If a material and maintain a thermal gradient then this provides an additional thermodynamic potential allowing higher efficiencies to be achieved.
You can even use hot-carrier materials as a spectral converters! I've worked on this approach over the last few years.
The following is multiple choice question (with options) to answer.
Solar cells convert the energy in sunlight to what type of energy? | [
"electrical energy",
"active energy",
"stellar energy",
"radical energy"
] | A | Solar cells convert the energy in sunlight to electrical energy. Solar cells are also called photovoltaic (PV) cells because they use light ( photo- ) to produce voltage ( -voltaic ). Solar cells contain a material such as silicon that absorbs light energy. The energy knocks electrons loose so they can flow freely and produce a difference in electric potential energy, or voltage. The flow of electrons creates electric current. Solar cells have positive and negative contacts, like the terminals in chemical cells. If the contacts are connected with wire, current flows from the negative to positive contact. The Figure below and following URL show how a solar cell works. http://www. suntreksolar. com/solarElectricity/howCellsWork. asp. |
SciQ | SciQ-5480 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
What occurs when a parent cell splits into two identical daughter cells of the same size? | [
"linear fission",
"symbiotic fission",
"twin fission",
"binary fission"
] | D | Binary fission occurs when a parent cell splits into two identical daughter cells of the same size. |
SciQ | SciQ-5481 | evolution, taxonomy
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild.
That last part takes care of the ligers and tiglons. But what if we consider plants? Under the definition I just gave, most grasses (around 11,000 species) would have to be considered as one species. In the wild, most grasses will freely pollinate related species and produce hybrid seed, which germinates. You might then think we could just modify the definition to specify that the offspring must be fertile (i.e. able to reproduce with one another)...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild to produce fertile progeny.
Unfortunately, the situation is still more complicated (we've barely started!). Often wild hybridisation events between plants lead to healthy, fertile offspring. In fact common wheat (Triticum aestivum) is a natural hybrid between three related species of grass. The offspring are able to breed freely with one another.
Perhaps we could account for this by taking into account whether the populations usually interbreed, and whether they form distinct populations...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of populations or meta-populations of related individuals that resemble one another, are able to breed among themselves, but do tend not to breed freely with members of another species in the wild to produce fertile progeny.
The following is multiple choice question (with options) to answer.
A group of individuals that consists of genetically related individuals that can breed to produce fertile young is known as what? | [
"species",
"community",
"population",
"colonies"
] | A | A species is a group of individuals that are genetically related and can breed to produce fertile young. Individuals are not members of the same species if their members cannot produce offspring that can also have children. The second word in the two word name given to every organism is the species name. For example, in Homo sapiens , sapiens is the species name. |
SciQ | SciQ-5482 | particle-physics, electromagnetic-radiation, accelerator-physics, synchrotron-radiation
Title: Do particle accelerators produce (dangerous) radiation? I was under the impression that particle accelerators were pretty harmless, but some article said that they produce harmful radiation when you're in the tunnel. Given that the Internet... isn't always correct, is this true? Yes, off the top of my head I can think of two major sources of harmful radiation:
Synchrotron radiation:
When charged particles are accelerated in a ring they emit EM synchrotron radiation. Depending on the frequency, this radiation can be dangerous.
Beam halo effects and internal beam interactions:
Beam halos, are particles in the accelerating bunch which are electromagnetically repelled from the beam centre. Particles in the beam halo are often lost to the walls of the beam-pipe. These, together with interactions in the beam can lead to various high-energy particles being produced.
The following is multiple choice question (with options) to answer.
What is the most dangerous type of radiation? | [
"plasma rays",
"gamma rays",
"sunlight rays",
"beta rays"
] | B | Gamma rays are the most dangerous type of radiation. They can travel farther and penetrate materials more deeply than can the charged particles emitted during alpha and beta decay. Gamma rays can be stopped only by several centimeters of lead or several meters of concrete. It’s no surprise that they can penetrate and damage cells deep inside the body. You can learn more about the effects of gamma radiation on people at this URL: http://library. thinkquest. org/3471/radiation_effects_body. html . |
SciQ | SciQ-5483 | organic-chemistry, redox, carbohydrates
That's all fine and dandy, but the thing is, I can't seem to find any source that (explicitly) explains why this whole 'ring-opening' business even happens in disaccharides like maltose, but not in sucrose.
The Wikipedia article probably implies that this has to do with the fact that both the monomers of sucrose are bound through their anomeric carbons, which is not the case with maltose. A quick look at the structures of maltose and sucrose confirms this, however; pardon me if I'm being dense here, but I don't see how that piece of information helps.
Can anyone explain this discrepancy? The difference in stability between maltose and sucrose boils down to the different structural elements their aldehyde/ketone groups have been turned into during the formation of the disaccharide.
In maltose, you combine two glucose units using the 1-hydroxy group of one and the 4-hydroxy group of the other. The 1-hydroxy group has been created in a process called acetal formation by the attack of what used to be the 5-hydroxy group and is now the ring oxygen. This is shown in equation $(1)$, the explicit carbon atom being carbon-1; the aldehyde.
$$\ce{R'-OH + RCHO <=>> R'-OH+-CHRO- <=>> R'-O-CHR-OH}\tag{1}$$
Notice that there are two oxygens bound to that carbon after the reaction; if we wanted, we could label it $\ce{RCH(OR)(OH)}$; this structure is called hemiacetal. If we use that hemiacetalic hydroxy group to bond to a second glucose unit,[1] we have replaced the hydrogen with an alkyl residue. Like the difference between alcohols ($\ce{R-OH}$) and ethers ($\ce{R-OR'}$), this group has a different reactivity and is termed full acetal or O,O-acetal.
The following is multiple choice question (with options) to answer.
What is the result when two monosaccharides are bound together? | [
"polyketide",
"disaccharide",
"Peroxide",
"hydrolysis"
] | B | The simple carbohydrates discussed above are used as the building blocks for complex carbohydrates. Monosaccharides like glucose or fructose can be linked together to form larger structures. When two monosaccharides are bound together, the result is a disaccharide . Some common disaccharides are shown in the Table below . |
SciQ | SciQ-5484 | meteorology, atmosphere, wind
$$
$R$ is the gas constant, $n$ is the particle number in moles, and $V$ is the volume. The conversion from moles to number of molecules is performed via the Avogadro constant.
We have in the order of $10^{10}$ particles and in the order of $10^{25}$ molecules per $m^3$. Hence, we are are dominantly hit by gaseous molecules (assuming equal speed of particles and moolecules which is not necessarily correct).
Answer
No, we are not mainly hit by nitrogen particles. However, we are mainly hit by nitrogen molecules.
The following is multiple choice question (with options) to answer.
What are the two major atmospheric gases? | [
"hydrogen and oxygen",
"nitrogen and oxygen",
"carbon and helium",
"nitrogen and hydrogen"
] | B | The major atmospheric gases are nitrogen and oxygen. The atmosphere also contains minor amounts of other gases, including carbon dioxide. |
SciQ | SciQ-5485 | 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 do you call the strands of dna wrapped around proteins, which are located inside the nucleus? | [
"ribosomes",
"fibrils",
"chromosomes",
"receptors"
] | C | Inside of the nucleus, you will find the chromosomes . Chromosomes are strands of DNA wrapped around proteins. They contain genes , or small units of genetic material (DNA) that contains the code for the creation of a protein. Human cells have 46 chromosomes (23 pairs). There are hundreds to thousands of genes on each chromosome. |
SciQ | SciQ-5486 | evolution
bacteria
cyanobacteria
archaea
protists
fungi
algae
plants
nematodes
arthropods
vertebrates
Bacterial and archaean colonisation
The first evidence of life on land seems to originate from 2.6 (Watanabe et al., 2000) to 3.1 (Battistuzzi et al., 2004) billion years ago. Since molecular evidence points to bacteria and archaea diverging between 3.2-3.8 billion years ago (Feng et al.,1997 - a classic paper), and since both bacteria and archaea are found on land (e.g. Taketani & Tsai, 2010), they must have colonised land independently. I would suggest there would have been many different bacterial colonisations, too. One at least is certain - cyanobacteria must have colonised independently from some other forms, since they evolved after the first bacterial colonisation (Tomitani et al., 2006), and are now found on land, e.g. in lichens.
Protistan, fungal, algal, plant and animal colonisation
Protists are a polyphyletic group of simple eukaryotes, and since fungal divergence from them (Wang et al., 1999 - another classic) predates fungal emergence from the ocean (Taylor & Osborn, 1996), they must have emerged separately. Then, since plants and fungi diverged whilst fungi were still in the ocean (Wang et al., 1999), plants must have colonised separately. Actually, it has been explicitly discovered in various ways (e.g. molecular clock methods, Heckman et al., 2001) that plants must have left the ocean separately to fungi, but probably relied upon them to be able to do it (Brundrett, 2002 - see note at bottom about this paper). Next, simple animals... Arthropods colonised the land independently (Pisani et al, 2004), and since nematodes diverged before arthropods (Wang et al., 1999), they too must have independently found land. Then, lumbering along at the end, came the tetrapods (Long & Gordon, 2004).
Note about the Brundrett paper: it has OVER 300 REFERENCES! That guy must have been hoping for some sort of prize.
References
The following is multiple choice question (with options) to answer.
Land could not be colonized by other organisms until what became established? | [
"oxygen",
"carbon dioxide",
"gases",
"plants"
] | D | All that changed when plants moved from water to land. This may have happened by 500 million years ago or even earlier. On land, everything was wide open. There were no other living things. Without plants, there was nothing for other organisms to eat. Land could not be colonized by other organisms until land plants became established. The earliest land plants may have resembled the modern liverworts in Figure below . |
SciQ | SciQ-5487 | electromagnetic-radiation, everyday-life
Title: Why do UV lamps look purple? UV radiation isn't visible to the human eye, so how come we can see it as a purple/violet light from a UV lamp? Is it just because the lamps aren't perfect and end up emitting some light at a higher frequency? Or do they add some purple light intentionally? Or is there some more complex mechanism going on? There are several kinds of "UV Light." Only kind I know of that "looks purple" is a so-called black light.
Black lights emit UV that is very close to the top-end of the visible spectrum. The designers try to minimize the visible radiation so that it won't wash out the light emitted by fluorescent substances in the field, but it's hard to filter all of the visible out.
The visible tail looks "purple" because the "red" receptors in your eye have some sensitivity at the shortest visible wavelengths. The visible leakage from a black light stimulates both "red" and "blue" receptors in your eye, and you perceive purple.
Other types of UV lamp (e.g., germicidal lamps) generally put out a lot of visible light that they don't bother to filter out because (A) it does not interfere with the application (e.g., visible light won't stop the UV from killing the germs) and (B) for safety reasons (i.e., so you know when you're looking at the light, which you shouldn't because it's dangerous.)
The following is multiple choice question (with options) to answer.
What are bacteria that stain purple are called? | [
"gram-positive bacteria",
"complex bacteria",
"gram-neutral bacteria",
"gram-negative bacteria"
] | A | Bacteria that stain purple are called gram-positive bacteria. They have a thick cell wall without an outer membrane. |
SciQ | SciQ-5488 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
When the bud is fully developed, it breaks away from the parent cell and forms a new what? | [
"organism",
"stem",
"leaf",
"flower"
] | A | Budding occurs when a parent cell forms a bubble-like bud. The bud stays attached to the parent cell while it grows and develops. When the bud is fully developed, it breaks away from the parent cell and forms a new organism. Budding in yeast is shown in Figure below . |
SciQ | SciQ-5489 | Problem 1 (Projectile motion with air resistance) We have seen in lecture that when an object is dropped from rest in the presence of both gravity and air resistance, Newton's second law of motion takes the following form where y is the height of the object above the ground, g is the local acceleration due to gravity near the earth's surface, c is a constant, and m is the object's mass. It can be used to explore relationships between mass, charge, velocity, magnetic field strength, and the resulting radius of the particle's path within the field. Computational Science Stack Exchange is a question and answer site for scientists using computers to solve scientific problems. The initial momentum in the x direction is provided only by the first object. Related Pages. Course Description. Because it is based on Python, it also has much to offer for experienced programmers and researchers. Software Architecture & LabVIEW Projects for $30 -$250. We can have different types of projectile type. First of all, this question is very similar (in a sense) to this one Projectile Motion with Air Resistance and Wind. A system of di erential equations will be interpreted from aerodynamics and drag to aid in. com/ http://simpson. We arrive at a prediction that adds the motion command to the mean, and has increased uncertainty over the initial uncertainty. For example, if you throw a ball up in air at an angle other than 0 o with the vertical, it follows a curved path which is called its trajectory. Dynamics - Newton's Second Law. The idea of the project is to illustrate the physical concept of projectile motion through a simple animation and a fun game!The mathematical equations of motion will be worked into a Python program and the path of the projectile will be plotted onto a 2-D graph. I am trying to predict the projectile motion of a basketball. Time of flight and range in projectile on inclined plane with detailed example (Hindi) Motion in Two Dimension. The projection motion is one kind of motion. I’m excited to show you all a whole new world of Generators in Python and hopefully inject a little bit of math into all your lives (cause everyone always needs a bit more math in their life), and also explain why counting problems are really hard for computers to do as they lead to such massive outputs with incredibly small changes to the input (. The motion of planets, or the heavenly bodies as they were known, is a fascinating subject. F d =
The following is multiple choice question (with options) to answer.
Arrows and cannon balls are examples of objects with what kind of motion? | [
"projectile",
"fluid",
"velocity",
"accelerating"
] | A | Examples of objects that have projectile motion include arrows and cannon balls. |
SciQ | SciQ-5490 | biochemistry, metabolism, bioenergetics
Title: What is the energy source for adipocytes? Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes? Adipocytes use glucose as an energy source. They express the insulin-responsive glucose transporter GLUT4 just like muscle cells so that when blood glucose levels rise they are primed to take the glucose up for fatty acid biosynthesis, but they also use glucose as a fuel molecule.
The following is multiple choice question (with options) to answer.
What is the sugar that the cells of living things use for energy? | [
"chlorophyll",
"insulin",
"glucose",
"sucrose"
] | C | Sugars are simple carbohydrates. Molecules of sugar have just a few carbon atoms. The simplest sugar is glucose (C 6 H 12 O 6 ). Glucose is the sugar that the cells of living things use for energy. Plants and some other organisms make glucose in the process of photosynthesis. Living things that cannot make glucose obtain it by consuming plants or these other organisms. |
SciQ | SciQ-5491 | physiology, neurophysiology, respiration, breathing, pulmonology
Title: Is breathing a reflex action or is it an intrinsic process? The process of breathing is controlled by respiratory centers in the brain stem. Do these centers have an innate activity, i.e., just send out signals to breathing muscles intrinsically, and have the rate and manner in which they do so modified by various regulatory factors?
Or are they driven by imbalances (in levels of oxygen, carbon dioxide, hydrogen ions) like a reflex? Let's say that hypothetically these levels remain static in an acceptable state such that this reflex is no longer needed, would breathing stop since there's no longer a driving motive or would it continue because the respiratory centers have an intrinsic activity? While the ultimate purpose of breathing could be considered to be the maintainance of a balance of the substances you are referring to (such as blood oxygen, carbon dioxide, and hydrogen ions), the blood levels of these substances do not directly control the production of action potentials within the motor neurons that promote the contraction of the diaphragm and intercostal muscles.
The propagation of these action potentials is initiated by signals from the medullary respiratory center, specifically the neurons in the dorsal respiratory group (DRG) and the ventral respiratory group (VRG). In the VRG, a complex of neurons known pre-Bötzinger complex is responsible for generating the signals that cause the rhythmic muscle contractions involved in breathing:
The respiratory rhythm generator is located in the pre-Bötzinger complex of neurons in the upper part of the VRG. This rhythm generator appears to be composed of pacemaker cells and a complex neural network that, acting together, set the basal respiratory rate.
The following is multiple choice question (with options) to answer.
What is the most important muscle involved in the process of breathing? | [
"chest",
"trachea",
"diaphragm",
"mouth"
] | C | How do lungs allow air in? Air moves into and out of the lungs by the movement of muscles. The most important muscle in the process of breathing is the diaphragm , a sheet of muscle that spreads across the bottom of the rib cage. The diaphragm and rib muscles contract and relax to move air into and out of the lungs. During inhalation, the diaphragm contracts and moves downward. The rib muscles contract and cause the ribs to move outward. This causes the chest volume to increase. Because the chest volume is larger, the air pressure inside the lungs is lower than the air pressure outside. This difference in air pressures causes air to be sucked into the lungs. When the diaphragm and rib muscles relax, air is pushed out of the lungs. Exhalation is similar to letting the air out of a balloon. |
SciQ | SciQ-5492 | acid-base
Title: Is the conjugate base of every polyprotic acid amphoteric? Since all compounds with an accessable free lone pair can act as a Brønsted-Lowry base, I was wondering if there was any specific example of a substance that when it loses a proton, it cannot accept a proton but can donate another proton.
Please note that I am not considering something like sulfuric acid which is a strong diprotic acid, as $\ce{HSO^{-}_{4}}$ still accepts a proton even if its to a limited extent. The conjugate base of sulfuric acid, bisulfate ion, shows little amphoteric character in water solution. Unless you drop the pH to about 2 or below, it is only an acid, and a moderately strong one at that.
The following is multiple choice question (with options) to answer.
What is the basic characteristic of monoprotic bases? | [
"accepts no neutrons",
"accepts one neutron",
"accepts no protons",
"accepts one proton"
] | D | Similarly, monoprotic bases are bases that will accept a single proton. Diprotic acids contain two ionizable hydrogen atoms per molecule; ionization of such acids occurs in two steps. The first ionization always takes place to a greater extent than the second ionization. For example, sulfuric acid, a strong acid, ionizes as follows: K a1 = more than 10 2 ; complete dissociation. |
SciQ | SciQ-5493 | energy, electrostatics, potential-energy
Title: where is electrostatic potential energy stored?
Potential energy can be defined as the capacity for doing work which arises from position or configuration.In the electrical case, a charge will exert a force on any other charge and potential energy arises from any collection of charges.
Where is this potential energy stored and how? That actually gets a bit tricky at the advanced level, but at the basic level, you should find somewhere in your textbook the equation $U = \int d^3x \left(\frac{1}{2} |\vec{E}|^2 \right)$ (maybe with a different constant up front, depending on what system of units the book is using). So at any point in space, the electric field $\vec{E}(\vec{x})$ at that point "stores" an amount of potential energy $\frac{1}{2} |\vec{E}|^2$.
The following is multiple choice question (with options) to answer.
What do we call a device used to store electric charge? | [
"capacitor",
"amplifier",
"battery",
"charger"
] | A | 19.5 Capacitors and Dielectrics A capacitor is a device used to store electric charge. Capacitors have applications ranging from filtering static out of radio reception to energy storage in heart defibrillators. Typically, commercial capacitors have two conducting parts close to one another, but not touching, such as those in Figure 19.13. (Most of the time an insulator is used between the two plates to provide separation—see the discussion on dielectrics below. ) When battery terminals are connected to an initially uncharged capacitor, equal amounts of positive and negative charge, +Q and – Q , are separated into its two plates. The capacitor remains neutral overall, but we refer to it as storing a charge. |
SciQ | SciQ-5494 | electricity, electrostatics, weather
Title: How can I prevent being zapped by static electricity every time I touch a doorknob or handle in the office? I don't know what it is about this office, but it seems everything I touch (doorknob, bathroom faucet, edge of kitchen sink in the break room), I get zapped by static electricity. It's getting old. I feel like that scene in Office Space.
I've worked in other offices and it's not nearly this crazy. This has been going on for months so it's not the weather.
Why does this happen and is there any way I can defend against this evil? My chair usually creates a lot of static, so the same happens to me. What I usually do is to touch any big metal object before I get up (my desk is metallic, so I use that) to discharge myself. Another popular trick is to touch the doorknob, faucet, etc with a metallic object, so that the discharge goes from that instead of your fingers. Or you can use an antistatic strap, if it really bothers you.
Regarding the physical processes, when you rub against other materials (e.g. a carpet) you can get electrically charged. That's called triboelectric effect. If you then touch a metallic object, there will be an electrical discharge, like a tiny ray, that goes from your skin to the object and can be painful but not dangerous. If the air is dry (like in an office with air conditioning), you'll build more charge because the humidity makes the air ore conducting and you will slowly discharge with no sparks.
The following is multiple choice question (with options) to answer.
Has this ever happened to you? you walk across a carpet, reach out to touch a metal doorknob, and get an unpleasant electric shock? .the reason you get a shock is because of what? | [
"sunlight charge",
"electrical charge",
"temperature charge",
"solar charge"
] | B | Has this ever happened to you? You walk across a carpet, reach out to touch a metal doorknob, and get an unpleasant electric shock (see Figure below ). The reason you get a shock is because of moving electric charges. Moving electric charges also create lightning bolts and the electric current that flows through cables and wires. |
SciQ | SciQ-5495 | geography, earth-system, astronomy, orbit, geodesy
(the vertical axis is logarithmic)
We can see that around 10 km away from the subsolar point, ~10 meters are enough to be closer than it to the Sun. ~30 meters at 20 km, ~800 meters at 100 km, ~3,000 m at 200 km, and if you go further than 340 km, not even Mount Everest will get you closer to the Sun.
So, the closest point to the Sun will be whatever geographical feature that maximizes the value $\text{Altitude}-\Delta H$, where $\text{Altitude}$ is the altitude of the geographical feature. Let's call that point “proxisolar” point. I just made up that name, but it will be handy for the following discussion.
Now that we understand the basis to establish what is the closest point to the Sun at a given moment, we can tackle the question that probably most people meant when asking this question:
What is the point on Earth that gets closest to the Sun over a year?
The most important fact to keep in mind, is that the variations of the distance between the Earth and the Sun over the year dwarf any topographical feature and even the diameter of the Earth itself. Earth’s distance from the Sun (center-to-center) varies from 147,098,074 km at perihelion (closest) to 152,097,701 km at aphelion (most distant). Therefore, the difference is 5 million kilometers!.
The perihelion happens around January 4th, when the solar declination is about -23°, therefore, the latitude of the subsolar point is around 23° South. That rules out Chimborazo, Cayambe and Everest, because they are too far to be the “proxisolar” point. In contrast, Sairecabur (5,971 m at 22.72° S) and Licancabur (5,916m at 22.83° S) are reasonable contestants.
The problem is that the perihelion happens on different days of the year and at different times of the day every year, so the point that gets closest to the Sun on a given year is just the one that happen to be the “proxisolar point” at the time of the Perihelion.
The following is multiple choice question (with options) to answer.
What planet is closest to our sun? | [
"Pluto",
"mercury",
"Venus",
"Earth"
] | B | Mercury is very close to the Sun, so it can get very hot. Mercury also has virtually no atmosphere. As the planet rotates very slowly, the temperature varies tremendously. In direct sunlight, the surface can be as hot as 427°C (801°F). On the dark side, the surface can be as cold as –183°C (–297°F)! The coldest temperatures may be on the insides of craters. Most of Mercury is extremely dry. Scientists think that there may be a small amount of water, in the form of ice, at the planet's poles. The poles never receive direct sunlight. |
SciQ | SciQ-5496 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
The ordovician-silurian extinction event is the first recorded mass extinction and the second largest. during this period, about what percent of marine species went extinct? | [
"40 percent",
"10 percent",
"85 percent",
"99 percent"
] | C | The Ordovician-Silurian extinction event is the first recorded mass extinction and the second largest. During this period, about 85 percent of marine species (few species lived outside the oceans) became extinct. The main hypothesis for its cause is a period of glaciation and then warming. The extinction event actually consists of two extinction events separated by about 1 million years. The first event was caused by cooling, and the second event was due to the subsequent warming. The climate changes affected temperatures and sea levels. Some researchers have suggested that a gamma-ray burst, caused by a nearby supernova, is a possible cause of the Ordovician-Silurian extinction. The gamma-ray burst would have stripped away. |
SciQ | SciQ-5497 | organic-chemistry, inorganic-chemistry, analytical-chemistry, materials
Title: How would I go about developing a linker molecule that binds SiO2? I'm trying to develop a molecule that acts as a bridge between a protein and surface of SiO2 lattice. The end that binds the protein is simple and easy but I can't figure out a way to draft up how I can get the other end to bind SiO2.
So my question is, anyone have an idea on what particular molecule or reaction I can look at that targets Silicon molecules or has a high affinity for binding specifically SiO2? It doesn't even have to be a chemical bond that links the bridge to the SiO2, it could be an electrostatic/polar interaction too.
Thank you. It is not easy to bind an organic molecule to silicium oxide. It is necessary to synthesize the Si-O bond. It cannot be done starting from $\ce{SiO2}$. A possibility is to react $\ce{CH3Cl}$ over elementary silicium at high temperature to carry out the reaction : $\ce{2 CH3Cl + Si > Si(CH3)2Cl2}$. Another approach is to make methyl sodium $\ce{NaCH3}$ react with gaseous $\ce{SiCl4}$ to produce : $\ce{SiCl4 + 3 NaCH3 -> Si(CH3)3Cl}$. These compounds can react with an alcool, like for example : $\ce{Si(CH3)3Cl + ROH -> Si(CH3)3OR + HCl}$. And here you obtain a molecule belonging to the class of the silicone. It contains the bond Si-O-C that you were looking for.
The following is multiple choice question (with options) to answer.
A small molecule that binds to a larger molecule is known as a? | [
"oxide",
"enzyme",
"lipid",
"ligand"
] | D | http://www. kentchemistry. com/links/Kinetics/entropy. htm. |
SciQ | SciQ-5498 | cardiology, embryology, pain, central-nervous-system
Title: At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'? According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed.
But according to this article, the heart starts beating at day 16.
And according to this article, the nervous system controls the rate beating of the heart.
Then my question is, **how can it be assured that the nervous system isn't developed until 19 weeks, when the nervous system controls the heart beating rate since day 16? First, there is some confusion on your part about heart cells and pain perception. Heart cells generate an action potential intrinsically; they do not need the central nervous system to beat (your second article explains this; read the part about the importance of calcium.) So yes, long before a fetus can feel pain, the heart is beating, because there must be circulation of nutrients throughout the embryo.
Secondly, the vagus nerve and sympathetic nerves can affect heart rate (the former by slowing it down when firing). These nerves start to reach their endpoints late in week 4 of development. So 19 days is not correct.
Cardiac sympathetic system
Although the primitive human heart starts to beat at 21 to 22 d, heart development continues to day 50, and it is near the end of this period, during the fifth week, that thoracic neural crest cells migrate from the neural tube through the somites and form aggregations (ganglia) near the dorsal aorta. [emphasis mine]
To experience pain, however, requires maturation of certain parts of the brain, most importantly, part of the thalamus and the cerebral cortex:
Current theories of pain consider an intact cortical system to be both necessary and sufficient for pain experience. In support are functional imaging studies showing that activation within a network of cortical regions correlate with reported pain experience. Furthermore, cortical activation can generate the experience of pain even in the absence of actual noxious stimulation. These observations suggest thalamic projections into the cortical plate are the minimal necessary anatomy for pain experience. These projections are complete at 23 weeks' gestation. [emphasis mine]
The following is multiple choice question (with options) to answer.
What process that begins in utero during fetal development and continues on into adolescence involves closing of the skull? | [
"calcification",
"elongation",
"ossification",
"incubation"
] | C | Intramembranous ossification begins in utero during fetal development and continues on into adolescence. At birth, the skull and clavicles are not fully ossified nor are the sutures of the skull closed. This allows the skull and shoulders to deform during passage through the birth canal. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt. |
SciQ | SciQ-5499 | genetics, homework
Title: law of independent assortment Self fetilization of F1 dihybrids, following independent assortment of alleles result in:
a) 3/16 Tall-rounds ; 3/16 dwarf-wrinkled
b) 9/16 Tall-wrinkled ; 3/16 dwarf-round
c) 9/16 Tall-round ; 3/16 dwarf-round
d) 3/16 Tall-wrinkled ; 3/16 dwarf-round
This question was asked in MCAT exam in Pak for which I'm preparing this year.... no genetic arcitecture was mentioned in question... The above mentioned is original format of question.... in ans-key, the ans is D but I am confused why it can't be C. In real life, round and tall are dominant traits in pea plants, which would make C and D both correct. I don't think people are expected to memorize the traits of pea plants, so the question ought to tell you somewhere which traits are dominant. There must be an error in the question as printed.
The following is multiple choice question (with options) to answer.
What traits are those that are inherited unchanged in a hybridization? | [
"alleles",
"dominant traits",
"mutations",
"recessive traits"
] | B | Upon compiling his results for many thousands of plants, Mendel concluded that the characteristics could be divided into expressed and latent traits. He called these dominant and recessive traits, respectively. Dominant traits are those that are inherited unchanged in a hybridization. Recessive traits become latent, or disappear in the offspring of a hybridization. The recessive trait does, however, reappear in the progeny of the hybrid offspring. An example of a dominant trait is the violetcolored flower trait. For this same characteristic (flower color), white-colored flowers are a recessive trait. The fact that the recessive trait reappeared in the F2 generation meant that the traits remained separate (and were not blended) in the plants of the F1 generation. Mendel proposed that this was because the plants possessed two copies of the trait for the flowercolor characteristic, and that each parent transmitted one of their two copies to their offspring, where they came together. Moreover, the physical observation of a dominant trait could mean that the genetic composition of the organism included two dominant versions of the characteristic, or that it included one dominant and one recessive version. Conversely, the observation of a recessive trait meant that the organism lacked any dominant versions of this characteristic. |
SciQ | SciQ-5500 | nutrition, hematology, metabolism
Title: How does a glucose molecule enter the cell from blood vessel? The transporters in the plasma membrane of the cells promote the entry of glucose molecules from the extracellular matrix to the cytosol of the cell. Could someone explain how does the nutrient molecule enter the extracellular space from the blood vessel?
For instance, in the context of the pancreas, the walls of the blood vessel is fenestrated. The literature also provides evidence for the presence of connexon in the endothelium of the capillaries.
My doubt is, the nutrient molecule that diffuses from the blood vessel reaches the cytosol of the cell through
Diffusing through connexon ?(or)
Does it reach the interstitial matrix(the fluid surrounding the cells) and then uptaken by the transporters present in the plasma membrane of the cell? I think I understand your question, Natasha. In short, your own answer #2 is correct.
There are 3 spaces, and 2 pathways for glucose to pass from one to the next:
intracapillary plasma
extracellular fluid
the cytosol.
Ways glucose gets into the cell:
(2->3) To get from the ECF to the cytosol , glucose always needs a transport protein. These are the GLUTs. In two cases, the small intestine and kidney, these are part of a secondary active transport system based on the Na/K-ATPase. In the pancreas, it's GLUT2.
(1->2) To get from the capillary plasma to the ECF requires filtration, the process of applying hydrostatic pressure to the plasma and literally squeezing it like a sponge. The boundary of the "blood sponge" is the basement membrane. The membrane holds in the proteins, and lets anything dissolved in the watery serum (like glucose) through.
The Filtration Constant Kf is proportional to the percentage of the BM that is exposed in a given capillary, which varies by the type and other factors like histamine release.
The following is multiple choice question (with options) to answer.
What is required to break down and build up molecules and to transport molecules across plasma membranes? | [
"calcium",
"electricity",
"salt",
"energy"
] | D | Inside every cell of all living things, energy is needed to carry out life processes. Energy is required to break down and build up molecules and to transport molecules across plasma membranes. All life’s work needs energy. A lot of energy is also simply lost to the environment as heat. The story of life is a story of energy flow—its capture, its change of form, its use for work, and its loss as heat. Energy, unlike matter, cannot be recycled, so organisms require a constant input of energy. Life runs on chemical energy. Where do living organisms get this chemical energy?. |
SciQ | SciQ-5501 | mineralogy, petrology
Title: How do you use the streckeisen (QAPF) classification ternary diagram to identify igneous rocks based on chemical rock composition? I have been given the following diagrams:
and
and a database that is structured like this:
ROCK NAME |SIO2 |TIO2| AL2O3| CR2O3| FEOT| CAO| MGO| MNO| K2O| NA2O| P2O5|
WEHRLITE |45.42| 0.17| 2.57| 0.32| 11.3384| 7.54| 31.93| 0.17| 0.01| 0.24| 0.01|
I want to know how to normalize the data and use these diagrams to identify the rock name based on the IUGS specification. I then am tasked to write a program that will do this automatically meaning that I have to come up with some semi-mathematically-based process to identify these rocks. Any ideas? Why you should not do it
The QAPF and related diagrams are intended for classification of rocks in the field, or preliminary classification with modal proportions as seen in the optical microscope. They are not designed with the chemical composition of the rocks in the mind. Furthermore, these diagrams are merely descriptive and not genetic. They do not take into account many factors affecting the various characteristics of the rocks. While doing something like this may be interesting for homework exercise, it is not something I would expect to see in a recent research article.
If you want to do it anyway
Your solution should consist of two steps.
The following is multiple choice question (with options) to answer.
The three main rock types are igneous, metamorphic, and what? | [
"basalt",
"sedimentary",
"silicate",
"crystalline"
] | B | The three main rock types are igneous, metamorphic, and sedimentary. |
SciQ | SciQ-5502 | virology, infection
Title: Why don't viruses cause wounds? A simple mental model of a viral infection is that an infected cell emits a lot of virions and eventually dies. The emitted virions have a chance of infecting other cells. Nearby cells are at a higher risk of infection.
Based on this model, if one cell in my nose gets infected, I would expect a large part of my nose to be destroyed, as the infection spreads and destroys more and more cells in the same area.
This does not happen! I survived a number of infections and still have my nose. Why?
I know there are "flesh eating" bacteria. Why isn't this the norm for infections? Does a common cold virus or SARS-CoV-2 not infect a lot of cells within the same area? A virus does not destroy that many cells before it is exterminated by the immune system or before the host dies.
Perhaps even more crucially, viruses typically target a very specific type of cell — those on the inner mucal surface of the nose in the case of cold or flu, those of the gastrointestinal tract in the case of stomach viruses, CD4 immune cells in the case of HIV, etc.
Update
As an example of how much time it takes for a virus to eat a noticeable wound, one could take the extermination of the immune cells by HIV - although it does not look as a physical wound, it is one, in the sense that enough of the specific tissue is destroyed to cause a life-threatening condition. It takes about a decade(!) - from the initial infection to the immune system failure.
On the other hand, the lethal effect of typical respiratory viruses is typically via obstructions of the respiratory ways due to inflammation or secretions resulting from the immune response, or via creating suitable conditions for a more serious bacterial infection.
The following is multiple choice question (with options) to answer.
What body part does encephalitis attack? | [
"liver",
"brain",
"lungs",
"heart"
] | B | Encephalitis is a brain infection ( Figure below ). If you have encephalitis, you are likely to have a fever and headache or feel drowsy and confused. The disease is most often caused by viruses. The immune system tries to fight off a brain infection, just as it tries to fight off other infections. But sometimes this can do more harm than good. The immune system’s response may cause swelling in the brain. With no room to expand, the brain pushes against the skull. This may injure the brain and even cause death. Medicines can help fight some viral infections of the brain, but not all infections. |
SciQ | SciQ-5503 | reproduction
Excerpts from the references that lead to the short answer above:
In the developing female fetus, oogonia become primary oocytes that begin the first division of meiosis. However, this division is not completed and the primary oocytes remain “frozen” in the prophase stage of the first meiotic division.
At birth, oogonia are no longer present. Each primary oocyte is surrounded by a single layer of squamous epithelial cells called follicular cells. The primary oocyte together with its follicular cells is called a primordial follicle. There are about two million primordial follicles with their primary oocytes in the ovaries at birth suspended in the first division of meiosis.
As the female grows, primary oocytes begin to die and disappear with their follicular cells. This process continues until puberty when there are only about 400,000 primordial follicles left in the ovaries. The primary oocytes continue the process of oogenesis after puberty begins.[Source]
The total number of primary oocytes at birth is estimated to vary from 700,000 to2 million. During childhood most oocytes become atretic; only approximately400,000 are present by the beginning of puberty, and fewer than 500 will be ovulated.[Source]
Primary oocytes reach their maximum development at ~20[6] weeks of gestational age, when approximately seven million primary oocytes have been created; however, at birth, this number has already been reduced to approximately 1-2 million.Recently, however, two publications have challenged the belief that a finite number of oocytes are set around the time of birth.[Source]
In the human embryo, the thousand or so oogonia divide rapidly from the second to the seventh month of gestation to form roughly 7 million germ cells.[Source]
REFERENCES:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0008772
The following is multiple choice question (with options) to answer.
What type of reproduction takes place when an animal simply divides into two parts? | [
"sexual reproduction",
"budding",
"fusion",
"fission"
] | D | Some invertebrates can also reproduce asexually. This may occur by fission or budding. Fission takes place when an animal simply divides into two parts. Each part then regrows the missing part. The result is two whole organisms. Budding may take place when a parent forms a small bump, or bud. The bud remains attached to the parent while it develops into a new individual. |
SciQ | SciQ-5504 | meteorology, atmosphere, wind, air-currents
Title: Where does wind come from? Wind is (according to Wikipedia) the flow of gases on a large scale.On the surface of the Earth, wind consists of the bulk movement of air.
What forces would cause such a mass movement of air? Wind is caused by pressure differences. Think of a balloon full of air; poke a hole in it and the air comes out. Why? Because the pressure in the balloon is higher than outside, and so to regain equal pressure, mass moves and that is the wind.
There is a bit more to this in the atmosphere as the Earth rotates and near the surface friction also plays a role. The equation of motion is the Navier-Stokes and in vector form in Cartesian space is:
$$\dfrac{\partial\mathbf u}{\partial t} = - \mathbf u \cdot \nabla \mathbf u -\dfrac{1}{\rho}\nabla p-2 \mathbf \Omega \times \mathbf u + \mathbf g + \mathbf F$$
In this equation, $\mathbf u$ is the vector wind, $(\mathbf u \cdot \nabla)$ is the advection operator, $\rho$ is density, $\mathbf \Omega$ is the vector rotation of the Earth, $\mathbf g$ is effective gravity and $\mathbf F$ is friction.
The LHS is the time rate of change of the wind at a point in space (as opposed to following the parcel). The RHS represent a number of factors that produce a change in the wind. From left to right:
Advection of momentum (non-linear)
Pressure gradient force (this is wind blowing from high to low pressure)
Coriolis force (this turns wind to the right in the NH and left in the SH and causes the wind to flow parallel to isobars)
gravity (provides hydrostatic balance with the PGF in the vertical)
Friction (in the boundary layer you may see this as $\nu\nabla^2\mathbf u$)
The following is multiple choice question (with options) to answer.
Winds moving air masses causes what? | [
"tremors",
"weather",
"earthquake",
"tsunami"
] | B | Global air currents cause global winds. The figure below shows the direction that these winds blow ( Figure below ). Global winds are the prevailing, or usual, winds at a given latitude. The winds move air masses, which causes weather. |
SciQ | SciQ-5505 | newtonian-gravity, dimensional-analysis, coulombs-law, physical-constants, order-of-magnitude
Title: Comparing the strength of gravity and electricity I often see and hear people claiming that "the gravitational force is much weaker than the electromagnetic force".
Usually, they justify it by comparing the universal gravity constant to Coulomb's constant. But obviously, such comparison is meaningless, as they differ in dimensions.
I'll make myself clear: of course you can say it is true for electron-electron interaction, but I'm talking about whether they can be compared fundamentally somehow in any area of physics. Yes, they can. Both interactions can be modeled using perturbative quantum field theory, where their strength is parametrized by a dimensionless coupling constant.
Electromagnetic repulsion between two electrons can be written as a power series in $\alpha$, the fine structure constant, which is dimensionless and has a value of roughly 1/137.
Meanwhile, the gravitational attraction between two electrons can be expanded in a similar way in a power series in $\alpha_G$, which is a dimensionless constant with a value of roughly $10^{-45}$.
The precise value of $\alpha_G$ depends somewhat on which particle you're comparing, since ultimately it's the square of the ratio of the particle's mass to the Planck mass. However, for fundamental particles, this ratio does not vary by more than ten orders of magnitude, which still places $\alpha_G$ far smaller than $\alpha$ no matter which fundamental particle you choose to compare.
The following is multiple choice question (with options) to answer.
How many orders of magnitudes bigger is the electric force? | [
"33",
"36",
"39",
"45"
] | C | and . The electric force is 39 orders of magnitudes bigger. |
SciQ | SciQ-5506 | zoology, ethology
Title: Is there a term for tool use in animals? Is there a technical/scientific term that scientists use to refer to tool making abilities found in certain types of animals?
Reference http://en.wikipedia.org/wiki/Animal_cognition#Tool_and_weapon_use Having read this article on tool use in Chimpanzees in full, I am inclined to say that if such a term existed then either the article itself or the titles of any of the 30 articles referenced would have included it.
Searching a couple of online biological dictionaries and ethology sites hasn't yielded anything either, therefore until someone else points out that I'm missing the obvious I'd say you're free to coin the term yourself!
The following is multiple choice question (with options) to answer.
What is the term for any way that an animal interacts with other animals or the environment? | [
"immunity",
"animal behavior",
"animal biology",
"animal way"
] | B | Animal behavior is any way that an animal interact with other animals or the environment. An animal may carry out behaviors alone or with other animals. The photos in Figure below show just a few of the ways that animals behave. Look at the pictures and read about the behaviors they represent. Why do you think the animals are behaving in these ways? And how do the behaviors come about? Which, if any of them, have to be learned?. |
SciQ | SciQ-5507 | mycology
Title: How do fairy rings propagate? It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, but what has been bizarre to me is how fairy rings form. Why do the fruiting bodies arrange themselves in a more or less circular shape, as opposed to the random scattering one would expect from wind-borne spores? When a fungal spore germinates in a suitable location, the growing mycelium will spread underground in all directions. In the ideal situation, the result is that the mycelium will become circular. Over time, the center of the mycelium will die out whereas the newly formed mycelium (underground) will develop the familiar mushrooms above ground and this will result in a fairy ring.
The following is multiple choice question (with options) to answer.
A mushroom is only a specialised reproductive part of the whole fungus. the main part of the fungi is underground in a whole web of hyphae, called this? | [
"mycelium",
"detritus",
"bacterium",
"hypothalamus"
] | A | Multicellular Photosynthetic Autotrophs hyphae are densely packed so it is difficult to see the individual structures when a mushroom is eaten. However, a mushroom is only a specialised reproductive part of the whole fungus. The main part of the fungi is underground in a whole web of hyphae, called a mycelium. In the mycelium, each fungal cell is separated from each other by a septum. Each fungal cell may have one or more nuclei and remains connected to the mycelium because the septa are porous, allowing cytoplasm to flow through the hyphae and fungal cell walls, made of a hard material called chitin. Some fungi do not have septa, and they appear to be large, branching, multinucleate cells. |
SciQ | SciQ-5508 | biochemistry, gas-laws
Title: What is the state of aggregation (gas, liquid) of oxygen in blood? Atmospheric oxygen is in O2 and a gas. Then we inhale the air, our efficient lungs do the magic to filter out the oxygen and push them into the blood stream.
When we say hemo and globin transport the oxygen using the iron ions. In what state oxygen is transported in the blood? as a gas or a liquid or an ion? It is hard for me to conceive of the idea that oxygen would be in gaseous form in the blood. "GAS in blood?" e.g. Arterial Blood Gas Test
Also, how does the lungs convert the gas into something that is compatible to be in blood?
References:
Amount of Oxygen in the Blood Regarding the state of oxygen in blood: It is in solution in the blood plasma (which mostly consists of water), in the form of single molecules. Think of water which you leave exposed to air: carbon dioxide will be captured and dissolved (along with the other gases in air), but these molecules are not gaseous or liquid, but rather "in solution", which is different from the "classical" states.
Back to oxygen: As your reference already states, most of the oxygen in solution will bind to hemoglobin. The actual state of oxygen in that complex has been debated, but it is believed to be reduced by the hemoglobin iron to the superoxide anion, coordinated to Fe$^{3+}$. See Wikipedia on this.
Also, the lungs do not "convert" the atmospheric oxygen to anything, they rather allow, due to their very large surface area, the quick exchange of oxygen/carbon dioxide in solution and in the air.
The following is multiple choice question (with options) to answer.
Most oxygen in blood is bound to a protein called what, and carried to the tissues? | [
"hemoglobin",
"platelete",
"hydrogen",
"plasma"
] | A | Transport of Oxygen in the Blood Although oxygen dissolves in blood, only a small amount of oxygen is transported this way. Only 1.5 percent of oxygen in the blood is dissolved directly into the blood itself. Most oxygen—98.5 percent—is bound to a protein called hemoglobin and carried to the tissues. Hemoglobin Hemoglobin, or Hb, is a protein molecule found in red blood cells (erythrocytes) made of four subunits: two alpha subunits and two beta subunits (Figure 39.19). Each subunit surrounds a central heme group that contains iron and binds one oxygen molecule, allowing each hemoglobin molecule to bind four oxygen molecules. Molecules with more oxygen bound to the heme groups are brighter red. As a result, oxygenated arterial blood where the Hb is carrying four oxygen molecules is bright red, while venous blood that is deoxygenated is darker red. |
SciQ | SciQ-5509 | visible-light, vision, photometry
Title: Can I see the light from 10 million km away? If light is switched ON, only for a second, and the distance between the observer and the light source is 10 million kilometers, can I still see the light spark?
For example, let's assume that the source is the Sun and the observer is a human eye. Yes it can be seen, given that you do not get much noise and that your sensor is sensitive enough for it to be able to detect the signal. As you have not specified anything about the light not much can be concluded, more than that it depends on the sensor, the transmitter and the noise from everything else.
The following is multiple choice question (with options) to answer.
What do we call the only light that people can see? | [
"visible light",
"spectral light",
"natural light",
"wave light"
] | A | The only light that people can see is called visible light . This light consists of a very narrow range of wavelengths that falls between infrared light and ultraviolet light. Within the visible range, we see light of different wavelengths as different colors of light, from red light, which has the longest wavelength, to violet light, which has the shortest wavelength (see Figure below ). When all of the wavelengths of visible light are combined, as they are in sunlight, visible light appears white. You can learn more about visible light at this URL: http://www. youtube. com/watch?v=PMtC34pzKGc . |
SciQ | SciQ-5510 | genetics, evolution
in a dioecious species (i.e., one with two sexes), cannibalism means a 50% chance of eating a potential mate and losing the opportunity to pass on your genes
diseases are more likely to transfer between species the more closely related they are. If you are a cannibal you are eating a species with a 99% similarity to you and are more likely to get diseases or parasites. Like kuru/mad cow/chronic wasting disease.
it precludes social behavior and all its benefits. Why engage in mutually profitable behavior when you can just eat those around you? This is thought to be one reason why pack-hunting is rare in some groups of vertebrates like monitor lizards.
on a broad-scale evolutionary perspective, cannibalism means removing members of your own population from the gene pool. It may be good for the individual but it's bad for the species as whole
cannibalism means you are feeding on an animal that is potentially your own size. That's a bad strategy in general. Most cannibalism in nature tends to be adults eating infants or adults scavenging carrion of their own species. By contrast predators are normally larger than their prey, with a few exceptions like pack-hunting wolves and lions.
The following is multiple choice question (with options) to answer.
Carnivores are animals that eat other animals. the word carnivore is derived from latin and literally means this? | [
"leaf eater",
"amount eater",
"meat eater",
"thick eater"
] | C | Carnivores are animals that eat other animals. The word carnivore is derived from Latin and literally means “meat eater. ” Wild cats such as lions, shown in Figure 34.3a and tigers are examples of vertebrate carnivores, as are snakes and sharks, while invertebrate carnivores include sea stars, spiders, and ladybugs, shown in Figure 34.3b. Obligate carnivores are those. |
SciQ | SciQ-5511 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
What term describes the sequential appearance and disappearance of species in a community over time after a severe disturbance? | [
"succession",
"generational replacement",
"pattern",
"supression"
] | A | Community Dynamics Community dynamics are the changes in community structure and composition over time, often following environmental disturbances such as volcanoes, earthquakes, storms, fires, and climate change. Communities with a relatively constant number of species are said to be at equilibrium. The equilibrium is dynamic with species identities and relationships changing over time, but maintaining relatively constant numbers. Following a disturbance, the community may or may not return to the equilibrium state. Succession describes the sequential appearance and disappearance of species in a community over time after a severe disturbance. In primary succession, newly exposed or newly formed rock is colonized by living organisms; in secondary succession, a part of an ecosystem is disturbed and remnants of the previous community remain. In both cases, there is a sequential change in species until a more or less permanent community develops. Primary Succession and Pioneer Species Primary succession occurs when new land is formed, for example, following the eruption of volcanoes, such as those on the Big Island of Hawaii. As lava flows into the ocean, new land is continually being formed. On the Big Island, approximately 32 acres of land is added to it its size each year. Weathering and other natural forces break down the rock enough for the. |
SciQ | SciQ-5512 | surface-tension, fluid-statics
Title: What happens to surface tension upon increasing surface area Pretty self explanatory title. But I just read in a book that the surface tension remains same even if the surface area is increased. What could be a possible explanation for that? The surface tension is a consequence of the interfacial energy. If you consider some area of the liquid surface $A$ then there is an interfacial energy proportional to the area:
$$ E = kA $$
for some constant $k$ that is dependent on the forces between the atoms/molecules in the liquid. If we increase the area of the liquid surface we increase its energy, and that means we have to do work on it. If we do work we must have been exerting a force on the boundaries of the surface, and the force per unit length of the boundary is what we call the surface tension.
The interfacial energy is a consequence of the atomic/molecular interactions in the liquid so the interfacial energy per unit area is a constant and not dependent on the total area. That means the surface tension is also dependent only on the interactions within the liquid and not on the total area.
The following is multiple choice question (with options) to answer.
What can water's high surface tension be attributed t? | [
"electric impulses in atoms",
"territorial molecules sticking together",
"polar molecules sticking together",
"molecules create a thin film-like substance"
] | C | Water has remarkable properties. Water expands when it freezes, even though all other substances contract. This means that in the winter ice on a pond or lake will float. Water has high surface tension because polar molecules tend to stick together. That's why drops stick together or some bugs can walk on the surface of a pond. Without water, life might not be able to exist on Earth. If it did exist, it would not be as diverse or as complex. |
SciQ | SciQ-5513 | rotation, habitable-zone, weather, astrobiology
One of the interesting historical facts of life on Earth, at least to me, is how long it took what we might consider advanced life to develop. One celled life in various forms was around for over 3 billion years but the first fossils are about 650 million years old. It took life a very long time on earth to get from too small to see to large enough to leave a footprint . . . but, I digress.
I agree 100%, one celled life or Tardegrades could live on a planet with no tilt or 90 degree tilt. Easy. Ocean life in general should be fine cause oceans are more adaptive. Evaporation keeps ocean surfaces colder than land gets during peak heat and while a completely frozen over ocean isn't great for life, cold oceans hold more oxygen and CO2 which can be good for life. Oceans also circulate as an effective means of temperature moderation and fish don't really care how windy it is or how much or little it rains. The tilt question, I think, is really just about life on land.
Land life could be more vulnerable to high wind, extreme temperature shifts, droughts or floods, which could be driven by greater axial tilt, but I find it hard to believe that Axial Tilt is the be-all and end all. Day length and year length are key factors too.
One point I agree with the article on, is that a close to 90 degree tilt might not be ideal with one part of the planet always facing the sun and the other part never facing it but outside of extreme tilts, I don't see why it would be a big deal.
A thick cloud cover, for example, reduces seasonal changes. There's a number of factors.
The following is multiple choice question (with options) to answer.
What supports life, and is also needed for the water cycle and weather? | [
"fossil fuels",
"oxygen",
"greenhouse gas",
"atmosphere"
] | D | We are lucky to have an atmosphere on Earth. The atmosphere supports life, and is also needed for the water cycle and weather. The gases of the atmosphere even allow us to hear. |
SciQ | SciQ-5514 | 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.
The zoospores develop into haploid, multicellular male and female gametophytes, which produce? | [
"gametes",
"spores",
"microorganisms",
"toxins"
] | A | |
SciQ | SciQ-5515 | equilibrium
Title: When volume decreases and the product has less moles than reactants, why is there no increase in the reaction quotient? Assume a reaction:
$$\ce{CO + Cl2 <=> COCl2}$$
My textbook says that a decrease in volume will result in the reaction quotient being less than the equilibrium constant. Why is that?
With a decrease in the volume, a forward reaction proceeds. Thus, more product and less reactant means there should be a higher reaction quotient. Keep in mind that for reaction
$$\ce{r_{1}R_{1} + r_{2}R_{2} + \ldots + r_{n}R_{n} <=> p_{1}P_{1} +\ldots + p_{m}P_{m}}$$
the reaction quotient is:
$$Q = \frac{\prod_{i = 1}^{m} [P_{i}]^{p_{i}}}{\prod_{j = 1}^{n} [R_{j}]^{r_{j}}}$$
Specifically, here:
$$Q = \frac{[\ce{COCl2}]}{[\ce{CO}][\ce{Cl2}]}$$
For your specific reaction, the reaction quotient is getting smaller because the denominator has a quadratic dependence on the pressure where as the numerator only has a linear dependence on pressure.
The goal as usual is to make $Q = K_{\mathrm{eq}}$, which is equilibrium.
Since now, $Q < K_{\mathrm{eq}}$, you want to push the reaction forwards. That will increase the concentrations of product and decrease the concentrations of reactant, making the reaction quotient bigger.
Intuitively, that makes sense in your example. There are two molecules combining to form one molecule. By decreasing the volume and increasing the pressure, you're squeezing them together into the product.
The following is multiple choice question (with options) to answer.
Reducing the number of molecules in a rigid container causes what to decrease? | [
"pressure",
"velocity",
"demand",
"energy"
] | A | The canister on the left contains a gas at a certain pressure. The attached air pump is then used to double the amount of gas in the canister. Since the canister cannot expand, the increased number of air molecules will strike the inside walls of the canister twice as frequently as they did before. The result is that the pressure inside the canister doubles. As you might imagine, if more and more air is continually added to a rigid container, it may eventually burst. Reducing the number of molecules in a rigid container has the opposite effect and the pressure decreases. |
SciQ | SciQ-5516 | natural-satellites
Title: Are moons geologically active? Are there natural satellites in the Solar System that are geologically active? This includes volcanism, existence and motion of tectonic plates, et cetera.
Is it a common or a rather rare feature among such bodies? Yes. Moons around Jupiter (Io, Europa and Ganymede), Saturn (Titan and Enceladus) and Neptune (Triton) all have some form of geological activity. Charon also may have geological activity, being in a binary system with Pluto. However, while Earth's geological activity is caused by internal heating and tectonic plates, the geological activity of the moons around Jovian planets comes in the form of tidal forces. Io is the most iconic instance of tidal stress, because Io's plumes are frequent, volatile and make the world look extremely chaotic, with its surface frequently being altered and renewed by its non stop volcanic activity. (Because it is chaotic)
As for tectonic plates, Europa is the closest you get to tectonic plates with moons in our star system. Water replaces lava when it comes to ice worlds. Ice worlds being worlds that have ice instead of rock for their crust. This means that water mantles are a frequent occurrence, with the core of ice worlds being mineral rich stone. This is the case for Triton as well, which has cyro-volcanism from the sheer tidal stress Neptune exerts on the captured dwarf planet.
Enceladus and Titan have water mantles, Enceladus being the world notable for its massive plumes, high albedo and tiger stripe surface fractures. Titan may also have tectonic activity for similar reasons to Europa.
The following is multiple choice question (with options) to answer.
What causes a lot of geological activity on the earth? | [
"weather",
"plate tectonics",
"natural selection",
"landslides"
] | B | Plate tectonic processes explain why we see many types of geological activity where we do. Stresses build up in some locations. These stresses may cause folding or faulting. Earthquakes strike along all three types of plate boundaries. The most damaging earthquakes are shallow focus. People in earthquake-prone regions must be aware of the potential damage from earthquakes. Seismologists have scales for measuring earthquake intensity and magnitude. Cities in earthquake zones must build safe structures. They also have guidelines for being safe in earthquakes. Earthquakes are often associated with volcanoes. Volcanoes erupt at all types of plate boundaries except transform. Volcanic eruptions can be quiet or explosive. Volcanoes have a variety of shapes. The shapes range from large shields, to classic peaks, to small cones. Supervolcano eruptions are rare but extremely deadly. Volcanic activity creates unique landforms. Hot springs and geysers result when water meets hot rock below ground. Some geological activity, both earthquakes and volcanic eruptions, is located away from plate boundaries. |
SciQ | SciQ-5517 | thermodynamics, physical-chemistry, chemical-potential, combustion
Title: How to thermodynamically understand process of burning a piece of coal? Let's imagine that I have a match in hand and nugget of coal on my desk. Then I light up the match and place it for few seconds near the coal so a tiny piece of nugget catches fire.
Then another piece catches fire, then another and soon all the nugget is burnt down.
How did it happen? I gave the nugget just enough heat to burn the first piece. Where does come energy to burn the rest of nugget from? It is called combustion, and it happens in materials which have a lower energy content when their component molecules join with the oxygen in the atmosphere, than when in a solid/liquid structure. When energy is given to start the fire the piece of coal burns and releases energy with excess enough to sustain the reaction and leave heat energy for use.
Combustion is a high-temperature exothermic chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.
The following is multiple choice question (with options) to answer.
The fuel that burns in a combustion reaction in many fossil fuels such as natural gas that consists of carbon hydrogen is known as what? | [
"catalyst",
"helium",
"fossil",
"hydrocarbon"
] | D | The fuel that burns in a combustion reaction is often a substance called a hydrocarbon. A hydrocarbon is a compound that contains only carbon (C) and hydrogen (H). Fossil fuels, such as natural gas, consist of hydrocarbons. Natural gas is a fuel that is commonly used in home furnaces and gas stoves (see Figure below ). The main component of natural gas is the hydrocarbon called methane (CH 4 ). The combustion of methane is represented by the equation:. |
SciQ | SciQ-5518 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What describes a combination of two or more substances, each of which maintains its own chemical identity? | [
"solute",
"mixture",
"structure",
"bond"
] | B | Water as a Component of Liquid Mixtures A mixture is a combination of two or more substances, each of which maintains its own chemical identity. In other words, the constituent substances are not chemically bonded into a new, larger chemical compound. The concept is easy to imagine if you think of powdery substances such as flour and sugar; when you stir them together in a bowl, they obviously do not bond to form a new compound. The room air you breathe is a gaseous mixture, containing three discrete elements—nitrogen, oxygen, and argon—and one compound, carbon dioxide. There are three types of liquid mixtures, all of which contain water as a key component. These are solutions, colloids, and suspensions. |
SciQ | SciQ-5519 | 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.
Sodium-potassium pumps help nerve cells establish a voltage across their what? | [
"sodium membranes",
"cell walls",
"potassium membranes",
"plasma membranes"
] | D | |
SciQ | SciQ-5520 | physical-chemistry, electrochemistry, reduction-potential
The correct answer given was $\ce{Br2(l)}$, however, this did not make sense to me as the oxidation of bromine would result in a positively charged bromine ion. Am I reasoning correctly that $\ce{O2(g)}$ can oxidize both $\ce{Ag}$ and $\ce{Br-}$ in acidic solution?
Since the value of $E^\circ$ for $\ce{O2(g)}$ is greater than both of the other values, more energy is released when $\ce{O2}$ gains the electrons, and this will result in the oxidation of both $\ce{Ag}$ and $\ce{Br-}$, correct? The sign of the electrode reduction potential is invariant. If reflects the sign of the electrostatic charge of the electrode with respect to the hydrogen electrode.* Also remember that all electrode potentials are written as reduction these days. This is a convention set by all electrochemists all over the world along with the other conventions. The following points are needed to approach this problem. I would suggest to solve this problem conceptually along with your own reasoning. It will give you a better understanding in future.
a) Ecell=Ecathode - Eanode > 0 implies a spontaneous reaction. (Eq. 1)
b) Don't change any signs of from tabulated values for Eq. 1. Eq. 1 already takes care of that. In the tables, carefully note that all reduced species appear on the left side and all the oxidized forms appear on the right. Reduction always occurs at the cathode, oxidation at the anode.
c) Ecell < 0, it implies a non-spontaneous reaction. However the reaction is spontaneous in the reverse direction.
Coming to your question. They are asking which substance can be oxidized by oxygen? They have also given you the starting materials/ elements.
Since oxygen is supposed to oxidize Br- and Ag, so it must reduce itself. Note that only reduced forms or the species on the right side of the equations of electrode potentials can be oxidized. Br- and Ag are reduced forms, that is why they were chosen for testing via Eq 1. This implies that we choose Ecathode as the oxygen half cell and test the oxidizable materials.
The following is multiple choice question (with options) to answer.
Tin is oxidized at the anode, while silver ion is reduced at? | [
"anodyne",
"gamma",
"iodine",
"cathode"
] | D | The standard cell potential is positive, so the reaction is spontaneous as written. Tin is oxidized at the anode, while silver ion is reduced at the cathode. Note that the voltage for the silver ion reduction is not doubled even though the reduction half-reaction had to be doubled to balance the overall redox equation. |
SciQ | SciQ-5521 | physical-chemistry
Title: why does adding a non volatile solute not decrease the boiling point? If I add a solute that decreases the bond strength of the pure solvent then wouldn't the solvent molecules evaporate more easily as it has lesser force holding it down now?But in my textbook, it's written that BP always increases when we add a non-volatile solute. Decrease of the solvent activity due its decreased molar fraction is bigger than the solvent activity increase due eventual solvent solute interaction.
So the pressure versus solute molar fraction curve may not be linear as by the Raoult law, but is monotonous.
The following is multiple choice question (with options) to answer.
Adding a solute does what to the boiling point of a pure solvent? | [
"silences it",
"increases it",
"reduces it",
"no effect"
] | B | Adding a solute increases the boiling point of a pure solvent. This change can be calculated using the equation . |
SciQ | SciQ-5522 | pathology
Title: Are all diseases caused by organisms (microorganisms)? Are there other causes? Or is it correct to say that all diseases are in fact caused by organisms (microorganisms)? It is not correct to say that all diseases are caused by foreign organisms. Counterexamples are:
Cancer is caused by random genetic mutations in the cells of our body. The mutations can be caused by many factors such as ionizing radiation, smoking, chemical toxins etc.
Diseases such as stroke or heart attack are caused by blood clots blocking the blood flow to essential organs.
Autoimmune diseases are caused by the immune system falsely recognizing cells of the body as foreign and attacking that tissue leading to a wide variety of symptoms.
Alzheimer's disease is caused by chronic neurodegeneration, meaning that the cells in the brain die. The causes are not quite understood but as Alzheimer's usually appears late in life it is likely related to ageing. Also, it is known that some genetic defects can lead to early-onset Alzheimers.
Prion proteins can cause diseases such as Creutzfeldt–Jakob disease also known as mad-cow disease.
Hereditary diseases such as early-onset Alzheimers or ALS are cause by gene defects inherited from the parents.
Toxins can cause chronic diseases such as lead poisoning.
The list probably goes on...
Please note that the first two on the list are the most common cause of death in developed countries.
The following is multiple choice question (with options) to answer.
Illnesses caused by bacteria in food are commonly known as what? | [
"the flu",
"chemical poisoning",
"food poisoning",
"viral poisoning"
] | C | Some pathogens spread through food or water. When harmful bacteria contaminate food, they cause foodborne illness, commonly called food poisoning. An example of a pathogen that spreads through water is the protozoan named Giardia lamblia, described in Table above . It causes a disease called giardiasis. |
SciQ | SciQ-5523 | bacteriology, ph, gut-bacteria
Any one of these is enough to have a bactericidal or bacteriostatic effect! This is also why cells that do live in slightly alkaline or acidic environments have to specialize, and they have narrow windows of pH that they can survive under, because they have to compensate so much to counteract the protonation or lack-thereof in their environments.
The following is multiple choice question (with options) to answer.
Most bacteria may be placed into one of three groups based on their response to gaseous? | [
"potassium",
"carbon",
"oxygen",
"nitrogen"
] | C | Most bacteria may be placed into one of three groups based on their response to gaseous oxygen. What are these three groups?. |
SciQ | SciQ-5524 | atmosphere, ozone, topography
Title: What are the causes of lower UV radiation at lower elevations? After recently visiting the Dead Sea in Israel and not getting any skin burns, I was wondering about the reasons for that. Searching the literature, it seems that the UV radiation is indeed lower in the Dead Sea (ca. -400 m) compared to Beer Sheva (a nearby city at ca. +300 m): 1 2 3. Both UVA and UVB rays are lower, but UVB rays are attenuated the most.
These sources give mostly measurements, but hardly discuss the reasons for the lower radiation. I always thought that the ozone layer blocks most of the UV radiation, but here it seems that just a few hundred meters of atmosphere can greatly reduce the amount of incident UV.
What are the reasons for that? Is it simply because there are more air molecules that absorb the radiation? You are almost totally correct when you asked:
What are the reasons for that? Is it simply because there are more air molecules that absorb the radiation?
The Ozone Layer blocks most of UVB, but does not affect the amount UVA entering the atmosphere (as seen in the illustration below):
(Image source)
But there is a little more to it than that. From NASA's Earth Observatory's webpage What Determines How Much Ultraviolet Radiation Reaches the Earth’s Surface?, elevation's role in attenuating UVB (and by similar processes, UVA):
high elevations UV-B radiation travels through less atmosphere before it reaches the ground, and so it has fewer chances of encountering radiation-absorbing aerosols or chemical substances (such as ozone and sulfur dioxide) than it does at lower elevations.
The aerosols absorb and scatter incident UV radiation. So nearer to the surface, there is a greater concentration that the light must pass through - and as the altitude decreases, the UV radiation path is therefore increased, so the further 'down' in altitude, the more the air mass and an increased presence of aerosols absorb and scatter solar UV radiation.
In respect to the aerosols in area you have specified (the Dead Sea), according to the first link in your question, The Analysis of the Ultraviolet Radiation in the Dead Sea Basin, Israel (Kudish et al. 1997), they state
the air above the Dead Sea is characterized by a
relatively high aerosol content due to the very high salt content of the Dead Sea
Their results indicate that
The following is multiple choice question (with options) to answer.
More uv rays reach the ground due to a decrease in what layer in the stratosphere? | [
"gases",
"ozone",
"smog",
"troposphere"
] | B | With less ozone in the stratosphere, more UV rays reach the ground. More UV rays increase skin cancer rates. Just a 1 percent loss of ozone causes a 5 percent increase in skin cancer. More UV rays also harm plants and phytoplankton. As a result, they produce less food. This may affect entire ecosystems. |
SciQ | SciQ-5525 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
Two species that share what cannot coexist in a community? | [
"mood",
"color",
"same niche",
"language"
] | C | |
SciQ | SciQ-5526 | angular-momentum, rotational-dynamics, torque, precession
Title: Angular momentum paradox I want to analyze the following system, where the mass of the axle is negligible and the Wheel is spinning.
In particular I need to calculate the amount of torque about the point where the string meets the axle.
Unfortunately I get two different answers depending on the procedure:
First (and correct) way
Taking into account the whole system, wheel and axle, there are two forces. The weight, with point of application the center of mass of the wheel; and a force with equal magnitude but opposite orientation, with point of application the place where the string meets the axle. Therefore there is a net torque.
Second (and wrong) way
Taking into account only the wheel, there are the same two forces, but both are applied to the center of mass of the Wheel. Therefore there is no torque.
Question
There must be some amount of torque because otherwise the wheel wouldn't experience precession, and it does. So why is my second approach wrong? Essentially you are asking why is neglecting the net torque on a system wrong, and the obvious answer it is because you fail to account for the change in angular momentum properly without torque.
Linear equations of motion relate net force to the motion of the center of mass. $$ \boldsymbol{F} = m \boldsymbol{a}_C $$
Rotational equations of motion relate net torque to the motion about the center of mass. $$ \boldsymbol{T}_C = \mathtt{I}_C \dot{\boldsymbol{\omega}} + \boldsymbol{\omega} \times \mathtt{I}_C \boldsymbol{\omega} $$
By neglecting the net torque you are not accounting for the gyroscopic forces correctly.
Look at a free body diagram of the separated parts from the side:
The torque $M$ is equal and opposite acting on the wheel such as to balance the forces on the axle.
The following is multiple choice question (with options) to answer.
In a wheel and axle, when force is applied either to the wheel or axle, what aspect of the force does not change? | [
"speed",
"shift",
"direction",
"pressure"
] | C | In a wheel and axle, force may be applied either to the wheel or to the axle. In both cases, the direction of the force does not change, but the force is either increased or applied over a greater distance. |
SciQ | SciQ-5527 | mass, measurements
Title: How precise can current technologies measure the mass of an object? Masses of various objects are listed on this wikipedia page: Orders of magnitude (mass). For example, mass of an HIV-1 virus is on the order of 1 femtogram.
Are these data actually measured (which I really doubt), or calculated?
What is the most precise measurement technique we have to measure the mass of an object? The most precise measurement of the mass of an electron was reported by Sturm et al in Nature 506, 467–470 (27 February 2014), quoting a relative precision of $3\times 10^{-11}$, meaning they determined the mass to better than $3\times 10^{-41}~\rm{kg}$.
If that is not the best, at least it gives you an upper bound...
Note that if you could weigh such a small mass directly with scales on earth, the force would be equivalent to the gravitational pull of a mosquito (mass 2.5 mg) on a grain of sand (0.7 mg) at a distance of about 6 million kilometers - about 17 times the distance to the moon...
Astonishing.
Acknowledgement: CuriousOne's comment got me thinking about the measurement of the mass of the electron, and led me to the above analysis.
The following is multiple choice question (with options) to answer.
What can be used to determine the mass of a quantity of material? | [
"atomic masses",
"inertial mass",
"gravitational mass",
"molar masses"
] | D | Molar masses can be used to determine the mass of a given quantity of material. |
SciQ | SciQ-5528 | organs, skin, pain, injury
Title: Why Is The Toughness Of Skin Different On Different Parts Of The Body? My cat was licking my arm with his sandpaper like tongue. It hurt and the area he was licking was slightly smarting afterwards. However, when he licks the palm of my hand the feeling is rather ticklish and results in no pain during or after.
We can pick up sharp, prickly, abrasive objects with our hands (palms/fingers) and even rub against them and have little to no damage incurred. However, if we do the same with say the back of our hand we are more likely to be injured.
I thought maybe the skin is thicker in our palms and that is resulting in our palms being more resilient. But, our palms are so sensitive to touch that it makes me think the skin is thinner to allow the nerves closer access to our environment.
Why is there such a stark difference in different areas of skin on our body when it comes to feeling pain and being susceptible to injury from scrapes, bruises, cuts, etc? As dd3 said the density of mechanoreceptors dictates skin sensitivity to touch (also look at penfield map. It is a nice illustration of how different senses are mapped to the brain and to what extent each region is sensitive to stimulus). Skin thickness is also different in different regions. This article says that Dikkopf1 (a Wnt pathway antagonist) controls skin thickness.
The following is multiple choice question (with options) to answer.
The thick skin, found only on the palms of the hands and the soles of the feet, has an extra what? | [
"Skin",
"layer",
"surface",
"outer"
] | B | The Epidermis The epidermis is composed of keratinized, stratified squamous epithelium. It is made of four or five layers of epithelial cells, depending on its location in the body. It does not have any blood vessels within it (i. , it is avascular). Skin that has four layers of cells is referred to as “thin skin. ” From deep to superficial, these layers are the stratum basale, stratum spinosum, stratum granulosum, and stratum corneum. Most of the skin can be classified as thin skin. “Thick skin” is found only on the palms of the hands and the soles of the feet. It has a fifth layer, called the stratum lucidum, located between the stratum corneum and the stratum granulosum (Figure 5.3). |
SciQ | SciQ-5529 | virus, antibiotics
Title: What are the positive effects of wrongful antibiotic use on a viral infection? I categorically accept that bacteria differ from viruses; so antibiotics DON'T help in viral infections. I also read this and this; so no need to explain this. I've read about the negative effects (eg exacerbation of antibiotic resistance); I ask only about the positive effects here, and NOT for reasons to exploit antibiotics for infections not due bacteria.
Yet I myself have witnessed that some people with viral infections feel better after wrongly taking antibiotics? and so asked about this first on Cognitive Sciences SE.
Initially, I suspected only some placebo effect, but this enlightened me on the side benefits of antibiotic consumption for a viral infection and motivated this question, now that my original question on psychology has revealed the relevance of biology. There are indeed antibiotics which have immunomodulatory side-effects, these are mostly from the class of macrolide antibiotics (erythromycin, clarithromycin, roxithromycin, azithromycin) and to some degree from the tetracyclines. Beta-lactam antibiotics (as Penicillin or Ampicillin) have not been shown to be immunomodulatory, but they are among the most commonly used. See reference 1 for more details.
The biggest effect has been shown on pulmonary diseases such as cystic fibrosis or diffuse panbrochiolitis (see reference 2).
Although the exact mechanism of action is not known, Macrolides are know to downregulate the inflammatory cascade and that the reduce the strong cytokine expression of some viral infections. However, these regulatory effects are relatively weak if you compare them to the anti-inflammatory properties of corticosteroids. So the question here is if the advantages are really sufficient compared to the problems, which an unnecessary use of antibiotics may cause. See reference 3 and the references in the paper for more details here.
Antibiotics may be useful to fight bacterial secondary or superinfections which accompany a virus infection.
References:
Immunomodulatory Properties of Antibiotics
Macrolide activities beyond their antimicrobial effects: macrolides
in diffuse panbronchiolitis and cystic fibrosis
Macrolide Therapy in Respiratory Viral Infections
The following is multiple choice question (with options) to answer.
What effect does tamiflu have on viruses and cells? | [
"inhibits spread of virus",
"enhances cells",
"destroys all viruses",
"reprograms viruses"
] | A | an enzyme (viral neuraminidase) that allows new virions to leave their infected cells. Thus, Tamiflu inhibits the spread of virus from infected to uninfected cells. Other antiviral drugs, such as Ribavirin, have been used to treat a variety of viral infections, although its mechanism of action against certain viruses remains unclear. |
SciQ | SciQ-5530 | materials
Title: Making Lyophilized Cake Lookalike using household ingredients I'm working on a machine learning model to identify flaws in vaccines in lyophilized cake form. To train the model, I need a number of samples that look something like this:
I have vials, but I'm having trouble making a suitable cake – I need something that will stick to itself when dried...
What I've tried so far:
Salt dissolved in water/isopropyl alcohol
Baking soda dissolved in water/isopropyl alcohol
Both of these turned back into powder (instead of caking) when dry.
Next, I'm considering using powdered detergent, adding water, then letting it dry...
How would you recommend making this using common household ingredients? You may want to consider whey. Looks like Karen Smith, Dairy Processing Technologist at the Wisconsin Center for Dairy Research, already did some of the work for you. The result depends on the specific type of whey (a high score of 4 or 5 on the caking test means the material cakes readily, forming a gummy crust):
Whey – (Scored 2-5) – whey exhibited a wide range of caking scores. How the whey is processed has a very large effect on the tendency of the resulting powder to cake as evident in this result. Clearly, two of the samples had large amounts of amorphous lactose and without the presence of significant amounts of protein the samples readily caked.
The following is multiple choice question (with options) to answer.
What is the main ingredient of mothballs? | [
"hydrocarbon naphthalene",
"stable naphthalene",
"ionized naphthalene",
"processed naphthalene"
] | A | A: The main ingredient of mothballs is the hydrocarbon naphthalene. The main ingredient in nail polish remover is the hydrocarbon acetone. The lawn mower runs on a mixture of hydrocarbons called gasoline, and the camp stove burns a hydrocarbon fuel named isobutane. |
SciQ | SciQ-5531 | plate-tectonics, crust, mantle, cavern
Title: How likely are caverns inside the mantle? Almost everyone wrongly assumes that the Earth's mantle is liquid, but it isn't (only the outer core is). Is it possible then that there are hollow spaces within the mantle, similar to caves in the crust? What could they look like and up to how much of the mantle could be hollow? What might be inside mantle caverns? Would they be filled with gas or rather vacuum? It is extremely unlikely that any hollow volumes exist in the mantle.
The mantle is a convecting solid which can deform over long timescales. Let's assume that such a cavern did somehow form. Whatever it is filled it, would be of lower density than the surrounding rock. It would slowly rise upwards through the solid-yet-deformable mantle until it reaches a place where the rocks are brittle, not ductile. That place is the crust. And as you know, the crust is full of caverns and there is no problem with that.
The following is multiple choice question (with options) to answer.
What is the column of hot rock that continuously brings hot rock up from the mantle toward the crust? | [
"volcanic vent",
"hotspot",
"mantle plume",
"flue"
] | C | Some volcanoes form over active hotspots . Scientists count about 50 hotspots on the Earth. Hotspots lie directly above a column of hot rock called a mantle plume . Mantle plumes continuously bring hot rock up from the mantle toward the crust ( Figure below ). The rock melts due to the release of pressure. |
SciQ | SciQ-5532 | electromagnetic-radiation, time, visible-light, frequency
Title: How many colors exist? How many "colors" do exist?
Our perception:
As far as I know, colors are just different frequencies of light. According to wikipedia, we can see wavelengths from about 380 nm und 740 nm. This means we can see light with a frequency from about $4.051 \cdot 10^{14}$ Hz to about $7.889 \cdot 10^{14} $ Hz. Is this correct? I don't know if time (and frequencies) are discrete or continuous values. If both are continuous, an uncountable number of "colors" would exist. If it is discrete, there might still exist no upper bound.
An upper bound? I found the article Orders of magnitude of frequencies. The Planck angular frequency seems to be by far higher than all other frequencies. Is this the highest frequency which is possible? Do higher frequencies make sense in physics?
Why do I ask this question: I am imagining the vector space $\mathbb{R}^4$ like the $\mathbb{R}^3$, but with colors. I need an infinite amount of colors if this should make sense. In fact the number has to be uncountable. A human eye may only distinguish thousands or millions of colors – obviously, one can't give a precise figure because colors that are too close may be mistakenly identified, or the same colors may be mistakenly said to be different, and so on. The RGB colors of the generic modern PC monitors written by 24 bits, like #003322, distinguish $2^{24}\sim 17,000,000$ colors.
If we neglect the imperfections of the human eyes, there are of course continuously many colors. Each frequency $f$ in the visible spectrum gives a different color. However, this counting really underestimates the actual number of colors: colors given by a unique frequency are just "monochromatic" colors or colors of "monochromatic" light.
We may also combine different frequencies – which is something totally different than adding the frequencies or taking the average of frequencies. In this more generous counting, there are $\infty^\infty$ colors of light where both the exponent and the base are "continuous" infinities.
The following is multiple choice question (with options) to answer.
What color light is actually the absence of electromagnetic waves in the visible spectrum, for humans? | [
"blue light",
"infrared light",
"black light",
"ultraviolet light"
] | C | The visible range of light (i. e. the range of wavelengths that our eyes can detect) is a very narrow piece of the full EM spectrum. In the visible range our eyes differentiate between the different wavelengths by producing ‘color’ for them. When we observe something that is green, it is green to us, because the wavelength of the light hitting our eyes is around 550 nm. If the wavelength of light is slightly larger than this it starts to look red, if it is slightly smaller it looks blue. White light is the combination of all the colors. Black light is the absence of EM waves in the visible spectrum for human beings. |
SciQ | SciQ-5533 | agriculture
The primary cereals for making bread are wheat and rye, while barley and oats may be mixed in. Historically significant portions of the rural population of Europe were sustained by cereal-based food in the form of gruel and porridge rather than by bread, especially prior to the introduction of the potato. Barley can be consumed in the form of pearl barley and groats and oats in the form of oatmeal. Especially in cool and humid climates not very suitable for cultivating wheat and rye, oats were once commonly cultivated and consumed. When Samuel Johnson wrote his dictionary, he famously defined oats as: "A grain which in England is generally given to horses, but in Scotland supports the people." A major historical and modern use of barley has been as malted barley, the main ingredient in beer brewing.
In the case of Finland it is interesting to note how late the transition from slash-and-burn agriculture to the use of permanent fields occurred. According to Teija Alenius, Environmental change and anthropogenic impact on lake sediments during the Holocene in the Finnish − Karelian inland area, Ph.D. thesis, University of Helsinki, 2007 (online)
The following is multiple choice question (with options) to answer.
What type of seeds come from plants that were traditionally grown in human populations, as opposed to the seeds used for large-scale agricultural production? | [
"modified seeds",
"old-fashioned seeds",
"heirloom seeds",
"original seeds"
] | C | larger cities and economic growth therein leads to the construction of dams, the consequent flooding of ecosystems, and increased emissions of pollutants. Other threats to tropical forests come from poachers, who log trees for their precious wood. Ebony and Brazilian rosewood, both on the endangered list, are examples of tree species driven almost to extinction by indiscriminate logging. The number of plant species becoming extinct is increasing at an alarming rate. Because ecosystems are in a delicate balance, and seed plants maintain close symbiotic relationships with animals—whether predators or pollinators—the disappearance of a single plant can lead to the extinction of connected animal species. A real and pressing issue is that many plant species have not yet been catalogued, and so their place in the ecosystem is unknown. These unknown species are threatened by logging, habitat destruction, and loss of pollinators. They may become extinct before we have the chance to begin to understand the possible impacts from their disappearance. Efforts to preserve biodiversity take several lines of action, from preserving heirloom seeds to barcoding species. Heirloom seeds come from plants that were traditionally grown in human populations, as opposed to the seeds used for large-scale agricultural production. Barcoding is a technique in which one or more short gene sequences, taken from a well-characterized portion of the genome, are used to identify a species through DNA analysis. |
SciQ | SciQ-5534 | organic-chemistry, inorganic-chemistry
But then, some inorganic compounds do have carbon too, and there may even be some compounds that some call organic, and others call inorganic, like $CO_2$.
As I have felt it, in my learnings so far, it's like inorganic chemistry is the default chemistry and organic chemistry goes a step beyond.
But I don't quite grasp the difference.
What is the real semantics behind the word "organic"?
For example, we humans are made of loads of water, and that's a pretty organic thing to me. But then, water is inorganic.
Diamonds are the carbon top of the cake, and do not transmit the idea of being an "organic" thing.
Another very confusing thing are polymers, chanins of loads of carbons with other elements, in many shapes and textures. To me, a piece of "plastic" is not a very organic thing, but indeed, they are!
That brings the semantics into an even more confusing level.
And of course, there must be historical reasons for those chosen words.
Could someone please point out where this distinction comes from and why it is important?
With all my respect to science and the people who made chemistry a useful thing. This question is not about critics, it's about not knowing the facts, so of course I am the ignorant here.
Related and useful: What is the definition of organic compounds? IUPAC is the International Union of Pure and Applied Chemistry, they make recommendations on the nomenclature. IUPAC mentions that the difference between organic and inorganic is not distinct. To quote "The boundaries between ‘organic’ and ‘inorganic’ compounds are blurred." in Brief Guide to the Nomenclature of Inorganic Chemistry R. M. Hartshorn, K.-H. Hellwich, A. Yerin.
Since the terminology of organic vs. inorganic is all human classification, it is not a binary system 0 or 1. What we can say now is that traditionally, all organic compounds do contain carbon. It can come from natural sources or purely synthetic. There is no such restriction. Plastic is an organic compound because it contains a lot of carbon chains.
Note that this word organic, as used in chemistry, has nothing to with the buzz word used in marketing of organic food, organic fruits, organically grown stuff. The word organic comes from French organique designating the jugular vein, hence related to organs or living beings.
The following is multiple choice question (with options) to answer.
What is the organic material that comes from plants and animals that were recently living called? | [
"biomass",
"biofuels",
"chlorophyll",
"contaminants"
] | A | Biomass is the material that comes from plants and animals that were recently living. Biomass can be burned directly. This happens when you burn a log in your fireplace. For as long as humans have had fire, people have used biomass for heating and cooking. |
SciQ | SciQ-5535 | thermodynamics, material-science, phase-transition, states-of-matter
Title: Why does matter exist in 3 states (liquids, solid, gas)? Why does matter on the earth exist in three states? Why cannot all matter exist in only one state (i.e. solid/liquid/gas)? The premise is wrong. Not all materials exist in exactly three different states; this is just the simplest schema and is applicable for some simple molecular or ionic substances.
Let's picture what happens to a substance if you start at low temperature, and add ever more heat.
Solid
At very low temperatures, there is virtually no thermal motion that prevents the molecules sticking together. And they stick together because of various forces (the simplest: opposite-charged ions attract each other electrostatically). If you picture this with something like lots of small magnets, it's evident enough that you get a solid phase, i.e. a rigid structure where nothing moves.
Actually though:
Helium won't freeze at any temperature: its ground state in the low-temperature limit at atmospheric pressure is a superfluid. The reason is that microscopically, matter does not behave like discrete magnets or something, but according to quantum mechanics.
There is generally not just one solid state. In the magnet analogy, you can build completely different structures from the same components. Likewise, what we just call “ice” is actually just one possible crystal structure for solid water, more precisely called Ice Ih. There are quite a lot of other solid phases.
Liquid
Now, if you increase temperature, that's like thoroughly vibrating your magnet sculpture. Because these bonds aren't infinitely strong, some of them will release every once in a while, allowing the whole to deform without actually falling apart. This is something like a liquid state.
Actually though:
The following is multiple choice question (with options) to answer.
What is the simplest form of matter that has a unique set of properties? | [
"molecule",
"element",
"quark",
"atom"
] | B | An element is the simplest form of matter that has a unique set of properties. |
SciQ | SciQ-5536 | climate-change, climatology
Thus, your question is a little misconstrued: we can't answer "Who are the 3%?" because the 3% are research articles rather than people. However, we can ask "Which are the 3% of published research abstracts which do not support the scientific consensus?" And since Cook et al. (2013) is an open access paper with supporting data provided, you can easily answer this question for yourself: simply download the data file from the supplementary data page and look at the papers with an endorsement rating of 5, 6, or 7. (It's in CSV format, so is easy to load into a spreadsheet or text editor.) Further supplementary data is available from the project page at Skeptical Science, and replication of the research is actively encouraged. If you're interested in the actual people behind the 3% of "non-consensus" papers you can look at the author lists for those publications (though of course there's no guarantee that all those authors would still stand by all their conclusions).
I suggest that you start your investigations by reading the paper itself. It's clear and concise, and will give you much more thorough information about the methodology and supporting data than I've been able to fit into this answer.
The following is multiple choice question (with options) to answer.
At least 20 percent of the world’s people do not have a ready supply of what? | [
"oil",
"clothing",
"food",
"clean drinking water"
] | D | The water Americans get from their faucets is safe. This water has been treated and purified. At least 20% of the world’s people do not have clean drinking water always available. That's more than 1 billion people. They must drink water from where they can get it. Maybe straight from a river or pond ( Figure below ). Human wastes may be in the water. If that's the case, the water will probably contain pathogens. Pathogens are organisms that cause diseases. |
SciQ | SciQ-5537 | mechanical-engineering, gears, applied-mechanics
Title: Is there a way rotate a wheel in a single direction but have opposing motions every 180 degrees? In order to give you a good idea of what I want to accomplish suppose you have a telescope mounted on a single rod extruding from the ground. The telescope is free to move such that you can tilt it to point at a particular altitude but can never point towards the ground. In order to move the telescope you have a wheel which can only be rotated in a single direction (say clockwise). Is there a gear configuration that would make a point alternate rotations every 180 degrees? and also have it configured such that the power loss is consistent throughout the entire cycle so that no half a cycle takes more power than the other?
Here is an illustration A crank (or 4 bar) type linkage can be forced to do this. In a crank mechanism there is a a point at bottom dead centre and top dead centre where the rotation could go in either direction regardless of the direction of the driving wheel/arm.
So you could have a stop which prevents the driven arm from rotating past 180 degrees, at which point it will naturally reverse direction. Note that steam trains have opposite wheels driven by cranks 90 degrees out of phase precisely to prevent this.
You could also use half gears (ie gears with no teeth on half of their circumference) along with an idler gear on one to achieve a similar effect.
There are also lots of different cam and multi-bar linkages which will produce reciprocating motion depending on your exact requirements.
The difference between the myriad of possible solutions will depend to a large extent on the function which relates input to output, particularly how linear it is throughout the range of movement.
For this sort of application it is also well worth looking through old patents as there are thousands and thousand of mechanical linkage patents out there for almost every imaginable mechanical application, many of which have now expired.
The following is multiple choice question (with options) to answer.
What simple machine consists of two connected rings or cylinders, one inside the other, which both turn in the same direction around a single center point? | [
"spoke",
"bloom and axle",
"pully",
"wheel and axle"
] | D | A wheel and axle is a simple machine that consists of two connected rings or cylinders, one inside the other, which both turn in the same direction around a single center point. When force is applied to the inner axle, the ideal mechanical advantage is less than 1. When force is applied to the outer wheel, the ideal mechanical advantage is greater than 1. |
SciQ | SciQ-5538 | human-biology, breathing
Our lungs work off of pressure. Specifically our lungs inflate by using "negative pressure" (a word I've always hated). The pressure is not actually negative it is simply lower than the surroundings. Since there is less air in your lungs the air from the atmosphere rushes in because the pressure is higher outside your lungs. This is Boyle's Law (not the pressure outside being higher, but what happens when your lungs expand). Where an increase in Volume means a decrease in Pressure (if all else remains unchanged). In fact plants pull water up using negative pressure.
However to push out the air from our lungs we supply pressure using our muscles that overcomes the outside pressure and forces the air out.
The reason you feel your breathing change is because when that train passes by you correctly observed the strong gust of wind. This gust of wind has some force behind it that normally is not in the air you are breathing from the atmosphere. It has more force which increases the air's velocity. This actually decreases the pressure, but there's no need to get into that here (Bernoulli's).
The reason it feels like your body is "fighting to breath" is because the air is traveling in a direction with some force that you need to overcome by opening up your lungs just enough to "suck" the air in with negative pressure. This is more than the pressure you usually need to produce in order to breath in air that is "still".
What is funny to think about is we don't really have a muscle that "pulls" air in, even though it feels like you are actively doing that. The air actually rushes in on its own. All you do is expand your rib cage, which your lungs are attached to (look up on how, it's actually pretty cool), thereby making inhalation occur.
Now an interesting question for you to ask yourself is why is cold air harder to breathe?
The following is multiple choice question (with options) to answer.
Birds have air sacs that store inhaled air and push it into their what? | [
"beaks",
"lungs",
"bones",
"abdomens"
] | B | Birds have air sacs that store inhaled air and push it into the lungs like bellows. This keeps the lungs constantly filled with oxygenated air. The lungs also contain millions of tiny passages that create a very large surface area for gas exchange with the blood (see Figure below ). |
SciQ | SciQ-5539 | earth, mars
Title: Does Mars contain more iron than the Earth? Is the reason Mars is red because its surface contains a lot of iron? (When dirt is red on Earth, it is sometimes caused by a high amount of iron).
If so, does Mars contain more iron than the earth? Mars definitely has far less Iron than Earth. Mars has 10.7% of Earth's mass. On the other hand, Iron comprises 32% of Earth since there is so much Iron in its inner core, outer core, and the mantle. That means if Mars was made entirely of Iron (which it is not), Earth would still have more than 3 times as much Iron.
You are right that Mars has more Iron at its surface than Earth so it looks very red. Earth has many other metals on its surface (not to mention water to make it look blue and plants to make it look green).
The following is multiple choice question (with options) to answer.
What is in the soil that causes mars to look red? | [
"sand",
"carbon",
"garnet",
"iron"
] | D | Viewed from Earth, Mars is red. This is due to large amounts of iron in the soil. The ancient Greeks and Romans named the planet Mars after the god of war. The planet's red color reminded them of blood. Mars has only a very thin atmosphere, made up mostly of carbon dioxide. |
SciQ | SciQ-5540 | thermodynamics, fluid-dynamics, thermal-conductivity, navier-stokes
I am not too familiar with this and would appreciate any guidence/help.
Thank you in advance! As a crude and quite simple approximation you could try the following.
The following is multiple choice question (with options) to answer.
Convection generally involves the transfer of what type of energy? | [
"thermal",
"radioactive",
"sunlight",
"magnetic"
] | A | Convection currents transfer thermal energy through many fluids, not just hot water in a pot. For example, convection currents transfer thermal energy through molten rock below Earth’s surface, through water in the oceans, and through air in the atmosphere. Convection currents in the atmosphere create winds. You can see one way this happens in the Figure below . The land heats up and cools off faster than the water because it has lower specific heat. Therefore, the land gets warmer during the day and cooler at night than the water does. During the day, warm air rises above the land and cool air from the water moves in to take its place. During the night, the opposite happens. Warm air rises above the water and cool air from the land moves out to take its place. |
SciQ | SciQ-5541 | newtonian-mechanics, forces, friction, free-body-diagram
Title: Implication of "gradually pulled\moved\pushed" in high school Newtonian physics In some of the physics problem I've been going over, the phrase "gradually pulled/moved/pushed" is coming up again. I can not understand what the implication of this is. Here is an example problem where it comes,
In the setup shown, a block is placed on a frictionless floor, the cord and pulleys are ideal and each spring has stifness $k$. The block is pulled away from the wall. How far will the block shift, while the pulling force is increased gradually from zero to a value $F$?
My concern what does the meaning of "gradual" in this case imply? Does the word play any vital role?
To be clear, I am not interested in the solution of above the problem, but rather what "gradually pulled" means in this post I think this remark is probably to avoid dealing with complications that arise if you were to not gradually exert a force. For instance, in real life if you yank on a box attached to a spring (the spring is attached to some wall as in your picture) and then hold the box with the same force you yanked it with, the spring will not just extend: it will wiggle and wobble and probably have some sort of wave motion going through it. In other words, the situation becomes more complicated. To avoid this potentially complicated spring behavior, we gradually increase the force exerted on the box.
It is the same general idea as the following. In some electricity and magnetism problems, we talk about "moving a charge such that the charge does not accelerate". We do not want the charge to accelerate because accelerating charges can introduce the complication of radiation.
The following is multiple choice question (with options) to answer.
What is the term for a push or a pull on an object? | [
"action",
"effort",
"gravity",
"force"
] | D | A force is a push or a pull on an object. When you place a book on a table, the book pushes downward on the table and the table pushes upward on the book. The two forces are equal and there is no resulting motion of the book. If, on the other hand, you hold the book in the air and let go, the force of gravity will pull the book to the ground. |
SciQ | SciQ-5542 | physical-chemistry, terminology
Title: Verb for Sorption Slightly silly question! Intuitively I want the present-simple verb for sorption to be "sorps", but saying it out loud, "sorbs" sounds much more natural. However, Google doesn't turn anything up for either of these, and they both make me sound like a redneck.
Since it definitely does not seem to be used often, it seems like the best choice would be to fall back to "adsorb" or "absorb", but I was wondering if there was a verb for the generalized sorption because it is a word I would like to use! Thanks. Yes, not surprisingly, the verb for sorption is sorb. It has been used for > 100 years in physical chemistry.
Here are the early references from the unabridged Oxford English Dictionary (by subscription only) so I cannot give you a link.
. transitive. To collect by sorption. Also absol.
1909 J. W. McBain in London, Edinb. & Dublin Philos. Mag. 6th Ser. 18 918 An idea of the quality of the carbon employed may be obtained from the amount of gas sorbed by it in actual experiment.
1938 Proc. Royal Soc. A. 167 407 The two zeolites in the form of three-dimensional networks sorb ammonia copiously without ammoniate formation.
1954 P. Alexander & R. F. Hudson Wool viii. 261 When wool is immersed in hydrogen peroxide, some is initially sorbed by the amino and imino groups without reaction.
1970 New Scientist 2 July 9/3 Papers with inked designs sorb best on the inked areas.
1972 Physics Bull. Oct. 583/1 This has the advantage that exhausted water vapour is not sorbed by the trap on the fine side of the pump.
The following is multiple choice question (with options) to answer.
What term is used to describe the process of removing wastes and excess water from the body? | [
"diffusion",
"digestion",
"excretion",
"aeration"
] | C | Excretion is the process of removing wastes and excess water from the body. It is one of the major ways the body maintains homeostasis. |
SciQ | SciQ-5543 | genetics, human-genetics
Title: skin colouration in thalassemia Now when i was studying about thalassemia, I read that anaemia is its major characterstic. I can understand that fact. But it was also written that the skin gets pale.
Wikipedia says that the skin turns yellowish.
I want to ask firstly is it that the skin gets darker when the affected person is exposed to sun and is otherwise pale?
And also why does the skin turn yellow/pale in the first place? Does that have to do something with Iron? Thalassemia is a genetic disease, in which either the alpha- or the beta-globins are missing or mutated. The hemoglobin of the blood is a protein complex which in adults consists of 2 alpha- and 2 beta-globin subunits. The ratio of these proteins needs to be exactly right, if one of them isn't produced enough or even missing, this leads to non-functional hemoglobin and subsequently abnormal erythrocytes.
These are then removed and broken down in the spleen (which is often abnormally enlarged), which also leads to the breakdown of the non-functional hemoglobin. The main product of the hemoglobin breakdown is Bilirubin, which is yellow. The yellow skin is a sign of jaundice, which is caused by high levels of Bilirubin in the blood.
The cause for the high Bilirubin levels in the blood of Thalassemia patients is the abnormal high rate of Hemoglobin breakdown.
The following is multiple choice question (with options) to answer.
Which disease occurs when there is not enough hemoglobin in the blood? | [
"Diabetes",
"anemia",
"Respiratory",
"Pulmonary"
] | B | Anemia is a disease that occurs when there is not enough hemoglobin (or iron) in the blood so it can’t carry adequate oxygen to the cells. There are many possible causes of anemia. One possible cause is excessive blood loss due to an injury or surgery. Not getting enough iron in the diet is another possible cause. |
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