source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-7144 | biochemistry, toxicity, halides
Title: Why are the halogens good disinfectants? I've been searching around the internet for a while and I know that Chlorine, Bromine and Iodine are used as disinfectants.
My question is, what is the property of the halogens that make them suitable for killing microbes? Is it just their toxicity? The halogens, particularly in their diatomic free states and within various oxoacids, are strong oxidizing agents by virtue of their high electronegativities, electron affinities, and reduction potentials. The polarizability of the heavier halogens also makes them almost uniquely versatile as both good leaving groups and strong nucleophiles, depending on conditions. Additionally, the relatively low bond dissociation energies of the halogens contribute to their aptitude to react by free-radical mechanisms (coupled with the exothermicity that usually accompanies the propagation of those reactions).
In their diatomic forms, they readily add across the $\pi$-bonds of alkenes and alkynes (which are ubiquitous and essential structural features of myriad types of biomolecules), and they can oxidize numerous other functional groups under the right conditions and in combination with other substances. Various oxoacids that incorporate halogens are often extremely strong oxidizers as well (household bleach, for example, is an aqueous solution of sodium hypochlorite, which is mild by comparison to certain other halogen-containing oxoacids). In those reactions, they typically serve to add oxygen to molecules in place of, e.g., hydrogen, while themselves serving as leaving groups (or parts of leaving groups).
The following is multiple choice question (with options) to answer.
What makes the halogen group so diverse? | [
"a single state of matter",
"contains alloys",
"three different states of matter",
"bonds easily"
] | C | The halogen group is quite diverse. It includes elements that occur in three different states of matter at room temperature. Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Halogens also vary in color, as you can see in the Figure below . Fluorine and chlorine are green, bromine is red, and iodine and astatine are nearly black. Like other nonmetals, halogens cannot conduct electricity or heat. Compared with most other elements, halogens have relatively low melting and boiling points. You can watch a lab demonstration of the melting and boiling points of halogens at this URL: http://www. youtube. com/watch?v=yP0U5rGWqdg . |
SciQ | SciQ-7145 | dating
Rather than damaging the fossils by dating them directly, the team looked to the sediments in which they were found. They discovered pieces of charcoal in sediments at similar depths, and considered those to be proxies for the ages of the fossils themselves. The charcoal bits were dated to around 19,000 and 13,000 to 11,000 years before present.
But Liang Bau boasts a devilishly complicated geological history, as layers of silt and clay interleave with layers of weathered limestone, loose gravel, and volcanic ash. In many places, these layers have been scoured by erosion, altered by seeping water, and jumbled by tectonic activity.
...
Dating on the gravelly sediment layer containing the fossils suggested it was deposited between 100,000 and 60,000 years ago; just above it is a layer of volcanic ash that was dated to about 60,000 years ago. This suggests that the fossils themselves couldn’t possibly be younger than 60,000 years old, the team reports online today in Nature.
To cap it off, the team has now directly dated the fossils themselves. Originally, researchers shied away from that analysis for fear of damaging them, Tocheri says. But this time, they felt they needed to do it. “It wasn’t until [we] were reasonably convinced that [the fossils] were probably older than 50,000 years old that we decided we needed to date them directly to be absolutely certain,” he says.
The team dated three arm bones found at different locations within the cave during previous excavations. Using uranium-thorium dating—which is based on the radioactive decay of uranium and thorium isotopes in a material—they found dates ranging from about 66,000 to 87,000 years old.
I could not find how the "charcoal bits" were dated, but it would be in the range for carbon dating.
The following is multiple choice question (with options) to answer.
What type of dating determines which of two fossils is older or younger than the other but not their age in years? | [
"normal",
"constant",
"normative",
"relative"
] | D | Relative dating determines which of two fossils is older or younger than the other but not their age in years. Relative dating is based on the positions of fossils in rock layers. Lower rock layers were laid down earlier, so they are assumed to contain older fossils. This is illustrated in Figure below . |
SciQ | SciQ-7146 | development
Title: How detachment/separation works in biology? It might be a strange question, but I'm interested in the mechanics of separation/detachment during asexual reproduction, for example when an organism reproduces by budding (I don't mean cellular budding like baker's yeast). When the newly formed body is fully matured it detaches itself from the parent / original body.
It might not be caused by a specific tissue, as animals with not so differentiated bodies are (also) capable of such, but I could easily be wrong. Is this (the detachment) triggered by changes in the cell membrane? I can't really think of other explanations. Reproductive budding and what you call 'cellular budding' are really highly related processes. Budding as a form of reproduction essentially partitions protein aggregates and damaged cellular components into the host or mother and builds fresh or 'young' cells on the opposite side of a partition. To begin understanding this look at Saccharomyces cerevisiae (budding yeast) which forms protein rings (from the septin proteins) at the membrane, around the bud neck which separates the mother and daughter cells Hartwell 1971. This ring acts a partition that in part, withholds protein aggregates and certain proteins from diffusing from the mother to the daughter. This protein ring is an example of how cells limit diffusion of proteins and cellular components to the daughter cell. Another good example that comes to mind is Linder 2007, though it is done in E Coli, not budding yeast, where mother cells maintain protein aggregates and age, while the daughter cells are given fresh components and are therefore more fresh and 'young'.
Now like you mention, imagine this process in a multicellular organism to be fundamentally the same. At some point the multicellular organism will start an outgrowth of cells, while restricting what materials are given to the daughter cells to maintain their youth. And eventually a new organism will have been created. Some of the details will be different, but the fundamental process is is quite similar. In that you start with an old cell that creates a new cell from scratch, but rather than splitting all cellular components equally between mother and daughter, the daughter cells is made in peak condition while the mother cell retains much of the cell 'junk' like protein aggregates.
Hopefully that starts to answer your question.
The following is multiple choice question (with options) to answer.
The timing of events in what cycle - which lasts just minutes in fruit fly embryos - is controlled by mechanisms that are both internal and external to the cell? | [
"life cycle",
"circadian cycle",
"cell cycle",
"carbon cycle"
] | C | culture (outside the body under optimal growing conditions), the length of the cycle is about 24 hours. In rapidly dividing human cells with a 24-hour cell cycle, the G1 phase lasts approximately nine hours, the S phase lasts 10 hours, the G2 phase lasts about four and one-half hours, and the M phase lasts approximately one-half hour. In early embryos of fruit flies, the cell cycle is completed in about eight minutes. The timing of events in the cell cycle is controlled by mechanisms that are both internal and external to the cell. |
SciQ | SciQ-7147 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
Is wind power renewable or non renewable? | [
"non renewable",
"neither",
"renewable",
"depends"
] | C | Wind power, a renewable resource, shown here in a modern wind energy farm. The wind is used to turn turbines that generate electricity. |
SciQ | SciQ-7148 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
What is the principal cell of connective tissues? | [
"neural",
"fibroblast",
"Cancer",
"organism"
] | B | Connective Tissues Connective tissues are made up of a matrix consisting of living cells and a non-living substance, called the ground substance. The ground substance is made of an organic substance (usually a protein) and an inorganic substance (usually a mineral or water). The principal cell of connective tissues is the fibroblast. This cell makes the fibers found in nearly all of the connective tissues. Fibroblasts are motile, able to carry out mitosis, and can synthesize whichever connective tissue is needed. Macrophages, lymphocytes, and, occasionally, leukocytes can be found in some of the tissues. Some tissues have specialized cells that are not found in the others. The matrix in connective tissues gives the tissue its density. When a connective tissue has a high concentration of cells or fibers, it has proportionally a less dense matrix. The organic portion or protein fibers found in connective tissues are either collagen, elastic, or reticular fibers. Collagen fibers provide strength to the tissue, preventing it from being torn or separated from the surrounding tissues. Elastic fibers are made of the protein elastin; this fiber can stretch to one and one half of its length and return to its original size and shape. Elastic fibers provide flexibility to the tissues. Reticular fibers are the third type of protein fiber found in connective tissues. This fiber consists of thin strands of collagen that form a network of fibers to support the tissue and other organs to which it is connected. The various types of connective tissues, the types of cells and fibers they are made of, and sample locations of the tissues is summarized in Table 33.3. |
SciQ | SciQ-7149 | population-dynamics, population-biology
Title: Spread of a benign virus in a population over time This is a somewhat difficult (for me) population dynamics question and I wonder if someone with experience in this area could suggest a reasonable approach?
My simplifying assumptions: As a gross oversimplification, let p(k) be the world's population at generation k, and assume a smooth exponential curve that models p(k) from $k=0$ at 10,0000 B.C.E to generation $k=600$ in 2000 C.E. A generation is 20 years, and in acc. with this Wiki there are about 4 million individuals at $k=0$ and 6070 million at $k=600.$
(Of course the exponential model is bad, as world population growth appears to have been sluggish before recorded history.)
Now assume a benign virus infects 120 individuals in $k=0.$ It benignly infects all individuals who have at least one infected parent. Perhaps unimportantly, it also continues to infect 30 new individuals per million in each generation (because its found in the soil), but would not infect those already exposed.
Call infected individuals II and non-infected NI. They are indistinguishable without clinical tests--which are not done, since the virus is harmless. Since II individuals are almost certain to mate with NI individuals, in earlier generations, the number of II will grow very quickly. For a time the growth rate of II will exceed that of p(k). At some point it will be unlikely that an II individual will encounter an NI mate, however a few NI persons will still pair with NI mates--for a while.
My question is, after 600 generations, what is a reasonable estimate of the percentage of II in the population? Is is possible that there would be any NI individuals left? Or would we have some sort of dynamic equilibrium between II and NI in which (I think) the former would strongly dominate?
FWIW, the population growth model is $p(k)=4e^{0.012 k}$ with $p(k)$ in millions. For simplicity, I denote the population of non-infected individuals by $N$ and the infected ones by $I$.
Model without soil infection
The following is multiple choice question (with options) to answer.
What occurs when a few individuals start, or found, a new population? | [
"novelty effect",
"founder effect",
"pioneer effect",
"outsider effect"
] | B | Founder effect occurs when a few individuals start, or found, a new population. By chance, allele frequencies of the founders may be different from allele frequencies of the population they left. An example is described in Figure below . |
SciQ | SciQ-7150 | human-biology, reproduction
Title: Why are animal births not taken as seriously as human births? When humans give birth, more than often medical assistance is needed. Others gather around and frantically look for any way to help. But when an animal gives birth, it is usually seen as a moment where you give the female its space and let the birth occur naturally and without any assistance. The animal is of course in serious pain just as a female human but this is more than often not taken into account. Why is it that animal births are not taken as seriously? Our heads are bigger.
There's some debate on the issue, but in essence, human brains, and therefore heads, are very large relative to our body size. This is handy for all the intelligent things we like to do, but can be rather painful during birth. Because we walk upright, the size of a newborn's head is actually a non-trivial fact during the birthing process. There are two major implications.
The first is that human birth hurts. You can watch the birth of other animals and they seem to brush it off, but for humans, forcing that huge head through a relatively small birth canal is difficult. Evolution has (supposedly) limited the size of the hips because, while that would allow an easier birthing process, it would negatively impact our ability to walk. As such, it has to hurt.
Secondly, in order to make the process easier, humans rotate during birth. The end result is that, unlike even other closely related primates, humans come out backward in a way that is very difficult for a birthing female to attend to. This almost requires having another person or two on hand to help out. This would, of course, be a huge reinforcement for social connections.
A few books I know of touch on this. Up From Dragons deals with the brain size/hip size issue and The Invisible Sex talks about rotation during the birthing process and the social implications.
The following is multiple choice question (with options) to answer.
When animals use incubation, how do they generally give birth to their young? | [
"live",
"eggs",
"copying",
"division"
] | B | In most species, one or both parents take care of the eggs. They sit on the eggs to keep them warm until they hatch. This is called incubation. After the eggs hatch, the parents generally continue their care. They feed the hatchlings until they are big enough to feed on their own. This is usually at a younger age in ground-nesting birds such as ducks than in tree-nesting birds such as robins. |
SciQ | SciQ-7151 | genetics, evolution, population-genetics, population-biology, allele
Title: Relationship between genetic diversity within and between species Here is a quote from Wagner (2008)
A second line of evidence [against neutralism] comes from the relationship between the mean number of polymorphic differences between alleles within a species, $\pi$, and the number of fixed differences between genes in two species, $d$. For neutral mutations, a positive association between $\pi$ and $d$ should exist, because the neutral theory predicts that both quantities are linearly proportional to the rate at which neutral mutations arise. Recent genome-scale data shows instead that this association is in fact negative.
What do "the mean number of polymorphic differences between alleles within a species" and "the number of fixed differences between genes in two species" have to do with each other? Why should there be any relationship at all? And by "two species", are they talking about Eastern Yellowback Whooping Finches versus Western Yellowback Whooping Finches, or any arbitrary two species, like E. Coli versus Muskrats?
I found this related question, but it doesn't say anything about different species. Metrics of interest
The two metrics you are interested in are
$\pi$ - the mean number of differences between two randomly sampled (with replacement) alleles in a population
$d$ - the mean number of differences between two randomly sampled (with replacement) alleles coming from two different species
Consider two sequences
ATCGTCAAT
ATAGTTAAT
There are 2 pairwise differences between these two sequences (positions 3 and 6).
The whole point here is to understand that two individuals in the same population coalesce at a given time in the past just like two individuals coming from two different species. The number of pairwise differences is just equal to the rate at which mutations accumulate multiplied by the coalescence time. Let me develop this idea with a few equations below.
Neutral Expectations
Let's do the math! We will do two important assumptions below.
Every mutation makes a new allele (it is an infinite allele model)
All mutations are substitutions (no indels, no gene duplication, etc...)
The following is multiple choice question (with options) to answer.
What two-word term refers to the number of different species in the community? | [
"species richness",
"face-richness",
"bacteria richness",
"group-richness"
] | A | |
SciQ | SciQ-7152 | homework-and-exercises, special-relativity, inertial-frames, observers
But in a different frame $S'$, event $B$ is not simultaneous with $A$! Instead, there is another event $B'$, on the same worldline as $B$, that is simultaneous with $A$ in the frame $S'$. And in the frame $S'$, the length of the object is the spatial separation between $A$ and $B'$, not $A$ and $B$. Since we're not considering the same pair of events in both frames, there is no reason to believe that the two spatial separations will be related in the same way they were in the first problem; and indeed, we do not get the same result.
As a general rule, the way to avoid "paradoxes" in special relativity is to carefully phrase everything in terms of "events". In the above example, carefully defining the idea of "length" in terms of simultaneous events makes it clear that the events in question must be different in different frames.
The following is multiple choice question (with options) to answer.
Two events are defined to be simultaneous if an observer measures them as occurring at what? | [
"different times",
"opposite times",
"midnight",
"same time"
] | D | 28.2 Simultaneity And Time Dilation • Two events are defined to be simultaneous if an observer measures them as occurring at the same time. They are not necessarily simultaneous to all observers—simultaneity is not absolute. • Time dilation is the phenomenon of time passing slower for an observer who is moving relative to another observer. • Observers moving at a relative velocity v do not measure the same elapsed time for an event. Proper time Δt 0 is the time measured by an observer at rest relative to the event being observed. Proper time is related to the time by an Earth-bound observer by the equation. |
SciQ | SciQ-7153 | electromagnetism, magnetic-monopoles, dipole, multipole-expansion
Title: Why do we need poles? The electric force is the attraction or repulsion between charges. If we for example had a metal with only positive charges, and another metal with only negative charges. The two metal pieces will then attract each other by the electric force. In an electric system, no poles is mentioned.
The magnetic force is just a relativistic side effect of the electric force, and the difference is that it is created by moving charges and acts on other moving charges. If we have the two metal pieces, they will also feel the magnetic attraction because of the particles inside the metals have motion. The two metals is then said to be magnets. However, in a magnetic system, poles is mentioned.
The following is multiple choice question (with options) to answer.
The force of attraction or repulsion between charged particles is called what? | [
"electric force",
"magnetic force",
"cooling force",
"power force"
] | A | When it comes to electric charges, opposites attract. In other words, positive and negative particles are attracted to each other. Like charges, on the other hand, repel each other, so two positive or two negative charges push apart from each other. The force of attraction or repulsion between charged particles is called electric force . It is illustrated in Figure below . The strength of electric force depends on the amount of electric charge and the distance between the charged particles. The larger the charge or the closer together the charges are, the greater is the electric force. |
SciQ | SciQ-7154 | evolution, botany, development, fruit, seeds
What is the point of fruit if not to be eaten? It’s my understanding that organisms will adapt to survive and thrive. I understand that being eaten can spread seeds, but this just seems like too much of a risky tactic to rely on.
Following on from part one: If being eaten is the best way to spread seed, why do some plants avoid this (such as by being poisonous or thorny)? Seeds are spread by many mechanisms
Wind dispersal: When air currents used to spread seeds. Often these plants have evolved features to facilitate wind catching, for example dandelions. Aka, anemochory.
Propulsion & bursting: When seeds are propelled from the plant in an such as in these videos. This is called Ballochory.
Water: Similarly to wind dispersal plants can spread seeds by water movement/currents, aka Hydrochory. This is used by many algae and water living plants.
Sticky Seeds: There are many ways a seed can attach to the outside of an animal - by using hooks, barbs, sticky excretions, hairs. Seeds then get carried by an animal and fall off later. This is epizoochory.
Fruiting: Plants can use seed-bearing fruit to encourage animals to eat the seeds. They will then be spread when the waste is excreted after digestion. This is a process of endozoochory.
More than one way to spread a seed
The following is multiple choice question (with options) to answer.
What important function do bees perform on garden plants and many commercial fruit trees? | [
"condensation",
"hibernation",
"pollination",
"ruination"
] | C | Pollination by Insects Bees are perhaps the most important pollinator of many garden plants and most commercial fruit trees (Figure 32.12). The most common species of bees are bumblebees and honeybees. Since bees cannot see the color red, bee-pollinated flowers usually have shades of blue, yellow, or other colors. Bees collect energy-rich pollen or nectar for their survival and energy. |
SciQ | SciQ-7155 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
What do ecosystems require constant inputs of? | [
"fuel",
"Water",
"energy",
"heating"
] | C | Ecosystems require constant inputs of energy from sunlight or chemicals. |
SciQ | SciQ-7156 | biochemistry
Alright so this is the oxidation of one mole of glucose equation (Without the ATPs) but till now I don't exactly know the correct answer for this question, but to not create any confusion this question is related to the Aerobic respiration (Glycolysis, Krebs Cycle and Electron transport chain).
Here's how I approached this question:
(a) is obviously not correct because the products of glycloysis are 2 pyruvate molecules and 2 ATP molecules so I checked off this choice.
(b) However seems correct because the products of 2 Krebs cycle is 4 CO2 and there is already 2CO2 when the pyruvate acid formed the 2 acetyl CoA molecules so in total that's 6CO2, but still what about the 6 Water molecules?
(c) is a very debating choice because when there is a "Complete occurrence of oxidative phosphorylation process" so that means 2 Krebs cycles had already occurred and formed the 6CO2, and during the oxidative phosphorylation process Water molecules are formed. and ATPs too? I don't exactly know about the ATPs, but aren't they supposed to be in the equation's products in order for this choice to be correct?
(d) This choice indicates to Krebs cycle but the water molecules only are formed during oxidative phosphorylation only.
So basically all the choices seems very debating and confusing and if I were to choose then I'll go with (C) because it's the only choice that makes sense for the water molecules (and the question asks for water), but I want someone to please answer this question with a brief explanation to why he chose this answer,
Thanks :) This reaction only means complete oxidation of glucose to 6 molecules of carbon dioxide and 6 molecules of water.
Reaction presented in question is very generalized, but the presence of six water molecules only means complete cellular respiration. Check out the actual biochemical pathways which take place to oxidize one glucose molecule.
And other options do not represent the complete cellular respiration, so there will not be formation of six water molecules, only option C means complete oxidation of glucose.
The following is multiple choice question (with options) to answer.
What is the final stage of aerobic respiration? | [
"proton transport",
"electron production",
"glucose transport",
"electron transport"
] | D | Electron transport is the final stage of aerobic respiration. In this stage, energy from NADH and FADH 2 is transferred to ATP. |
SciQ | SciQ-7157 | optics, visible-light, planets, liquid-state, exoplanets
The low-energy part of the UV absorption spectrum of the molecule consists of two diffuse bands with maxima at excitation energies of E ∼ 8.4 and 9.3 eV.
The following is multiple choice question (with options) to answer.
What is the lightest molecule? | [
"hydrogen",
"silicon",
"helium",
"oxygen"
] | A | Based on their molar masses, hydrogen is the lightest molecule, and oxygen is the heaviest. Because all three volumes are the same, each balloon contains the same number of gas molecules. Therefore, the hydrogen balloon will have the lowest mass, and the oxygen balloon will have the highest. |
SciQ | SciQ-7158 | dna, dna-sequencing, genomes, human-genome, mouse
I hope this is understandable, if you need any clarification on terms, please ask :)
The following is multiple choice question (with options) to answer.
The genome of an organism consists of one or more what? | [
"hemoglobin molecules",
"dna molecules",
"rna molecules",
"require molecules"
] | B | Copying and passing on genes (genetics) In which we consider the dynamics of genes and gene expression, and how genome dynamics leads to families of genes and facilitates evolutionary change. We consider how DNA is organized within a cell and how its organization influences gene expression. Finally we consider the behavior of regulatory networks at the molecular level and the role of molecular level noise in producing interesting behaviors. At this point we have introduced genes, DNA, and proteins, but we have left unresolved a number of important questions. These include how genomes are organized, how they evolve, how new genes and alleles are generated, and how they work together to produce the various behaviors that organisms display.327 We will touch on such trendy topics such as epigenetics (which is probably less interesting than most suppose) and the rather complex molecular and cellular level processes behind even the simplest biological behaviors. The details, where known–and often they are not–are beyond the scope of this course, but the basic themes are relatively straightforward, although it does takes some practice to master this type of thinking. The key is to keep calm and analyze on! Genomes and their organization Genomes are characterized by two complementary metrics, the number of base pairs of DNA and the number of genes present within this DNA. The number of base pairs is easier to measure, we can count them. This can, however, lead to a mistaken conclusion, namely that the number of base pairs of DNA within the genome of a particular species, organism, or even tissue within an organism is fixed and constant. In fact genomes are dynamic, something that we will return to shortly. The genome of an organism (and generally the cells of which it is composed) consists of one or more DNA molecules. When we talk about genome size we are talking about the total number of base pairs present in all of these DNA molecules added together. The organism with one of the largest known genomes is the plant Paris japonica; its genome is estimated to be ~150,000 x 106 (millions of) base pairs.328 In contrast the (haploid) human genome consists of ~3,200 x 106 base pairs of DNA. The relatively small genome size of birds (~1,450 x 106 base pairs) is thought to be due to the smaller genome size of their dinosaurian ancestors.329 That said there are interesting organisms that suggest that in some cases, natural selection can act to dramatically increase or decrease genome size without changing gene number. For example, the carnivorous bladderwort Utricularia gibba, has a genome of 327. |
SciQ | SciQ-7159 | species-identification
Title: Identification of a lifeform There's a video I found on Facebook and I'm unable to figure out what the creature featured happens to be.
Adding images that have been taken from the video itself, apologies in advance since they're not high qualify images.
Can anybody shed any light on what it is?
The video was shot near Ratan Babu Ghat which is situated along the bank of Hooghly river, Kolkata, West Bengal, India. Here to be precise. This is a polyclad flatworm.
Here is a video of notoplana vitrea moving similarly to the one in the video that you linked:
https://www.asturnatura.com/especie/notoplana-vitrea.html
Here is a gallery of polyclad flatworms observed in India:
https://inaturalist.ca/observations?place_id=6681&subview=grid&taxon_id=52318
A number of the images in this gallery look similar to the one in your video, but very few of them are identified beyond this order taxon of polyclad flatworm.
The following is multiple choice question (with options) to answer.
Where are free-living roundworms mainly found? | [
"arboreal habitats",
"ocean depths",
"rainforests",
"freshwater habitats"
] | D | Free-living roundworms are found mainly in freshwater habitats. |
SciQ | SciQ-7160 | centrifugal-force, centripetal-force
Similarly, a centripetal force is needed to make you go in a circle. If you sit there, you have to apply a force outwards which we call centrifugal force, to use Newton's laws.
Centripetal force is a force which provides acceleration towards centre, say, Tension while moving the object round with string. So if, you apply $F=ma$ from the revolving object, you have to add centrifugal force as the object is at rest wrt itself.
You can explain what you experience while turning due to you inertia which resists you change in motion.
The following is multiple choice question (with options) to answer.
What do you call any force that makes something move in a circle? | [
"momentum",
"centripetal force",
"tangential force",
"cyclical"
] | B | Centripetal Force is an umbrella term that refers to any force that makes something move in a circle. Examples of forces that can be centripetal forces are as follows: Gravity (the gravity between the Earth and Sun causes the Earth to go in a circle), Friction (the friction force between a car’s tires and the road causes the car to turn), Tension (when swinging a bucket around in a circle by holding onto the string, the tension of the string is the centripetal force). |
SciQ | SciQ-7161 | biophysics, theoretical-biology, ecosystem
Systems ecology, especially with regard to energy and nutrient flow.
This type of ecology can be strongly influenced by physics. For one example see the book Theoretical Ecosystem Ecology: Understanding Element Cycles by Ågren & Bosatta (Ågren was originally a physicist)
Physical limitations to growth and transport
This can include for instance mechanical contraints on plant growth (see e.g. the book Plant Physics by Nicklas & Spatz), water transport in trees (see e.g. this BioSE question) or the biomechanics of movement (see e.g. Hudson et al (2012) on the speed and movement of cheetahs or Wikipedia: Biomechanics).
Allometric relationships between organisms, e.g. with regard to metabolism
To explain these types of relationships knowledge in physics is useful. See e.g. Kleiber's law for more.
MAXENT as a general approach to ecological patterns or to model species distributions
This is basically a tool lifted from physics that can be applied to ecological problems. There are many papers to look at, but Harte & Newman (2014) (Harte is another previous physicist) and Elith et al (2010) are two good starting points.
Dynamical modelling of populations and communities
This field use many of the same tools for analysis as physics, e.g. systems of differential equations. One of the pioneers in this field (among many) were Robert May (also started with a PhD in physics), and his classical book Theoretical Ecology: Principles and Applications is still a good starting point.
Energy harnessing and conversion by organisms
This can refer both to how organsims convert prey to energy (e.g. conversion efficiencies) and the physics of photosynthesis (which is an interesting intersection between physics and molecular biology). See Jang et al (2004) and O'Reilly & Olaya-Castro (2013) for examples of the how quantum mechanics can inform us about photosynthesis.
Hopefully this will give you a sense of some different ways that knowledge in physics can be useful for biology.
The following is multiple choice question (with options) to answer.
The two parameters used to measure changes in ecosystems are resistance and what related factor? | [
"strength",
"acceptability",
"resilience",
"variation"
] | C | Ecosystems are complex with many interacting parts. They are routinely exposed to various disturbances, or changes in the environment that effect their compositions: yearly variations in rainfall and temperature and the slower processes of plant growth, which may take several years. Many of these disturbances are a result of natural processes. For example, when lightning causes a forest fire and destroys part of a forest ecosystem, the ground is eventually populated by grasses, then by bushes and shrubs, and later by mature trees, restoring the forest to its former state. The impact of environmental disturbances caused by human activities is as important as the changes wrought by natural processes. Human agricultural practices, air pollution, acid rain, global deforestation, overfishing, eutrophication, oil spills, and illegal dumping on land and into the ocean are all issues of concern to conservationists. Equilibrium is the steady state of an ecosystem where all organisms are in balance with their environment and with each other. In ecology, two parameters are used to measure changes in ecosystems: resistance and resilience. The ability of an ecosystem to remain at equilibrium in spite of disturbances is called resistance. The speed at which an ecosystem recovers equilibrium after being disturbed, called its resilience. Ecosystem resistance and resilience are especially important when considering human impact. The nature of an ecosystem may change to such a degree that it can lose its resilience entirely. This process can lead to the complete destruction or irreversible altering of the ecosystem. |
SciQ | SciQ-7162 | metabolism, human-anatomy, pharmacology, liver
For drugs introduced through an injection, for example, metabolism occurs throughout the circulatory system and in the liver. Remember that it's all the same blood supply, but the first-pass effect just refers to the blood that goes to the liver before entering the systemic circulation (by which it can travel to its target).
The following is multiple choice question (with options) to answer.
In humans, the first sites used for energy storage are liver and what else? | [
"skin cells",
"lungs",
"reproductive organs",
"muscle cells"
] | D | |
SciQ | SciQ-7163 | condensed-matter, solid-state-physics, semiconductor-physics
Title: Is there a energy lower to -13.6 eV in a given atom/element? The Hydrogen atom fundamental energy is -13.6 eV.
Is there an atom that has an energy level lower to -13.6 eV ?
if no, then why, in semiconductor physics, the integral on energy start at $-\infty$ instead of $-13.6\ eV$ ? Yes. Neglecting effects of other electrons, the ground-state energy scales like $Z^2$. So probably all other elements have more negative ground-state energies than hydrogen does.
I recommend reviewing either the Bohr or Schrodinger models for a hydrogen-like atom that has a nucleus that has $Z$ protons.
The following is multiple choice question (with options) to answer.
What are electrons at the outermost energy level of an atom are called? | [
"core electrons",
"valence electrons",
"ions",
"shell electrons"
] | B | Electrons at the outermost energy level of an atom are called valence electrons. They determine many of the properties of an element. That’s because these electrons are involved in chemical reactions with other atoms. Atoms may share or transfer valence electrons. Shared electrons bind atoms together to form chemical compounds. |
SciQ | SciQ-7164 | An example of an "unjustified step" occurred famously in Andrew Wiles's first announcement that he had proved Fermat's Last Theorem. Someone (actually, I think multiple people) found a mistake in the proof he presented. After he made a considerable additional effort, he was finally able to present a proof without that mistake, and this proof was accepted.
Some comments under the original question raised the issue of how we check the intermediate steps of a proof by contradiction, claiming that it is easier to check the steps in a direct proof since their conclusions are all true.
Things that we want to prove typically have the form $S\implies T,$ for which a direct proof typically involves assuming $S$ and then showing that $T$ follows. In the intermediate steps of the proof, we have some facts that depend on $S,$ which we cannot "check" by simply observing that they are true; we can check them by verifying the logic in every step leading up to that part of the proof, or we can check them by coming up with an alternative proof showing that they follow from $S.$
We may also introduce some known facts (which do not depend on $S$) in the course of the proof, which we can check simply by verifying that they are true facts.
A third possibility is that we derive something from $S$ that we could have known to be true without assuming $S.$ This is wasteful; we could improve the proof by simply introducing these facts as known without showing a logical derivation from $S.$
The same things happen in proof by contradiction. We will have some steps that we can check only by checking every step in the logic leading up to them or by devising an alternative proof, we may have known facts that we can check more easily, and we may even have wasted effort by deriving something from our (false) assumption that we could have simply brought in as a known fact.
The following is multiple choice question (with options) to answer.
Reaching conclusions about unobserved things on the basis of what has already been observed is known as what kind of reasoning? | [
"conductive",
"inductive",
"reductive",
"primitive"
] | B | Inductive reasoning involves reaching conclusions about unobserved things on the basis of what has already been observed. Induction is used regularly in fields such as archaeology, where inferences about the past from present are made. Inductions could also be made across outer space, as in astronomy, where conclusions about the whole universe are drawn from the limited number of observations we are able to make. |
SciQ | SciQ-7165 | organic-chemistry, nomenclature
So, $\ce{C_205H_412}$ is the molecular formula of pentadictane. $\ce{C_7547H_15096}$ is heptatetracontapentactaheptaliane.
The following is multiple choice question (with options) to answer.
The molecular formula is still c 4 h 10 , which is the same formula as? | [
"propane",
"carbon hydroxide",
"butane",
"chlorine"
] | C | The name of this molecule is 2-methylpropane. The molecular formula is still C 4 H 10 , which is the same formula as butane. A structural isomer is one of multiple molecules that have the same molecular formula, but different structural formulas. Butane and 2-methylpropane are structural isomers. |
SciQ | SciQ-7166 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
A structure composed of two or more types of tissues that work together to perform the same function is called? | [
"System",
"organ",
"Group",
"order"
] | B | The four types of tissues make up all the organs of the human body. An organ is a structure composed of two or more types of tissues that work together to perform the same function. Examples of human organs include the skin, brain, lungs, kidneys, and heart. Consider the heart as an example. Figure below shows how all four tissue types work together to make the heart pump blood. |
SciQ | SciQ-7167 | cancer, mutations
Here is another great paper that specifically addresses your question, linking increased cell division with the accumulation of both significant and insignificant mutations, which over time, lead to an accumulation of mutations needed for cancer to develop.
The following is multiple choice question (with options) to answer.
All cells undergo what during a lifetime, but when this process is out of control, cancer results? | [
"cell division",
"cell death",
"cell transition",
"cell mutation"
] | A | Cell division is just one of the stages that all cells go through during their life. This includes cells that are harmful, such as cancer cells. Cancer cells divide more often than normal cells, and grow out of control. In fact, this is how cancer cells cause illness. In these concepts, you will read about how cells divide, what other stages cells go through, and what causes cancer cells to divide out of control and harm the body. |
SciQ | SciQ-7168 | biochemistry
Hence the substrate-binding site of α-amylase does not have access to the residues that need to bind for it to perform hydroysis of glycogen, and, indeed, the enzyme that breaks down glycogen — glycogen phosphorylase — is specific for these free ends.
The α-amylases that can hydrolyse both α-1,4 and α-1,6 glycosidic links are quite few compared with those with specificity to one or the other type of linkage (see Table 2 of the MacGregor review, if you can obtain access to it). The impression obtained from following up two of the examples there is that the enzymes involved can exist in alternative conformations, the correct one of which is triggered by the substrate. An example is the glycogen debranching enzyme, the studies of which in Sulfolobus solfataricus and Candida glabrata can be read freely on-line. Although somewhat less directly relevant, the example of a Thermoactinomyces vulgaris neopullulanase is another variation on this theme.
The following is multiple choice question (with options) to answer.
Amylase and pepsin are examples of enzymes needed for what process? | [
"absorption",
"digestion",
"fermentation",
"filtration"
] | B | More than 1000 different enzymes are necessary for human life. Many enzymes are needed for the digestion of food. Two examples are amylase and pepsin. Both are described in the Figure below . |
SciQ | SciQ-7169 | genetics
So the modern definition of a phenotype is the observable characteristics of an organism, anatomical, physiological or behavioral. The first 2 points are easily accepted and uncontroversial. But there is debate about what exactly should be included in "behavior". I'm going to ignore behavior for now.
An important point, and I think this is where there is disagreement between Remi.b and me, is that a phenotype must have a genetics basis. I realize this is not explicitly mentioned in any definition, but that is very much the way people mean it. And if not, the definition is totally meaningless. Take the example of a monkey missing a finger congenitally. This is a phenotype, it is due to its genes. If the monkey is missing a finger due to a fight, this is not a phenotype because genes have nothing to do with it (again, ignoring behavior for now).
So, in my opinion, what would not be a phenotype is something that you could conclusively prove to have no genetics basis whatsoever. That's an extremely (impossible) hard case to make. But in retrospect I was perhaps to quick to include behavior in the definition, and this is due to my own biases as a behavioral neuroscientist.
I think this is the narrow definition of phenotype and I don't think anyone would disagree up to that point. You might notice that there has been no mention of evolution so far. It is because genetics and evolution have been developed independently, and even though everybody was quite aware they must be 2 sides of the same coin evolution is not directly relevant to the genotype/phenotype distinction.
The following is multiple choice question (with options) to answer.
What two words describe the debate over whether behaviors are caused by genetics or by environment? | [
"positive and negative",
"kinetic and potential",
"dominant and recessive",
"nature and nurture"
] | D | Some behaviors seem to be controlled solely by genes. Others appear to be due to experiences in a given environment. Whether behaviors are controlled mainly by genes or by the environment is often a matter of debate. This is called the nature-nurture debate . Nature refers to the genes an animal inherits. Nurture refers to the environment that the animal experiences. |
SciQ | SciQ-7170 | solar-system, space, comets, radiation, dust
Title: How can comets have tails if there's no air resistance in space? I understand that solar radiation causes material to vaporize out of a comet into dust but why does the dust then trail behind the comet like a "tail"?
Assuming gravity is the only applied force acting on the comet, shouldn't all of the material, including the dust, be travelling at the same speed due to conservation of momentum? What causes the dust to travel slower than the comet's nucleus? In other words, why does the dust form a "tail" and not a "cloud"? There are two forces that can cause the formation of a tail: the solar wind and radiation pressure.
The first misconception in your question is "the dust [travels] slower than the nucleus". The tail is not left trailing behind the comet, it is pushed away from the comet by the sun. When the comet is moving away from the sun, the tail is in front of the comet.
Now radiation pressure is small but real. When light shines on something there is a small force. This pushes dust back from the comet in the direction opposite to the sun. The dust is still affected by gravity and a curved dust tail results.
The ultraviolet light from the Sun ionises the gas and gives it an electric charge. The solar wind carries magnetic fields and the gas (or more properly plasma) follows these fields in a straight line back from the sun.
So space around the Sun is not empty. There is powerful light and magnetic fields that are strong enough to push the dust and gas released by the comet away from the coma, and form the tail.
The following is multiple choice question (with options) to answer.
Why do comet tails always point away from the sun instead of trailing behind the comet? | [
"dust particles attract",
"dust particles evaporate",
"dust particles liquify",
"dust particles recoil"
] | D | Figure 29.17 shows a comet with two prominent tails. What most people do not know about the tails is that they always point away from the Sun rather than trailing behind the comet (like the tail of Bo Peep’s sheep). Comet tails are composed of gases and dust evaporated from the body of the comet and ionized gas. The dust particles recoil away from the Sun when photons scatter from them. Evidently, photons carry momentum in the direction of their motion (away from the Sun), and some of this momentum is transferred to dust particles in collisions. Gas atoms and molecules in the blue tail are most affected by other particles of radiation, such as protons and electrons emanating from the Sun, rather than by the momentum of photons. |
SciQ | SciQ-7171 | polymers
Title: What do people mean with "per unit volume" in polymer solutions theory? I am reading Modern Theory of Polymer Solutions by Hiromi Yamakawa and in the context of the virial expansion the following puzzles me a bit:
"...expanded in terms of solute concentration $c$ (in gramms per unit volume)...
"...Thus, by use of the relation $ρ = N_A c/M$ with $N_A$ the Avogadro number, $c$ the solute concentration (g/cc), and $M$ the solute molecular weight..."
What exactly does unit volume mean in this context? And how can I interpret the unit g/cc? Unit volume is a volume equal to 1 standard volume unit in the system of units you are using.
In most contexts (like this one) it shows up as "per unit volume". In this case it is because we are discussing density. Density is mass "per unit volume".
In your question they give the units $\frac{g}{cc}$. This is a bit confusing if you don't know much about unit labeling. "$cc$" is one way to say "cubic centimetres" (probably more common some places than others, in Canada I rarely see it that way besides in the medical community and engine sizing). I find it far less confusing to keep it as $cm^3$, as then it's obviously cubic centimeters.
You can also have "unit mass" and "unit time" for example, and things are often measured in "per unit mass" and "per unit time".
I can think of a couple very common and good reasons to use "unit values". Often times materials and situations can be expressed in a way where they scale linearly with some variable. Mass of an object scales linearly for an object with uniform density (mass per unit volume). This means that if you know the density of a material, and it's volume, you can calculate the weight.
The following is multiple choice question (with options) to answer.
What is the term for the average number of individuals in a population per unit of area or volume? | [
"population diameter",
"Density group",
"population structure",
"population density"
] | D | Population density is the average number of individuals in a population per unit of area or volume. For example, a population of 100 insects that live in an area of 100 square meters has a density of 1 insect per square meter. If the same population lives in an area of only 1 square meter, what is its density? Which population is more crowded? How might crowding affect the health of a population?. |
SciQ | SciQ-7172 | thermodynamics, energy, free-energy, molecular-dynamics
I think "total energy" would be the internal energy. It would be great if someone could please confirm/debunk that--I don't know if the situation is distinct for distinct ensembles, for example. Whatever the case, I don't know how it relates to the free energy. I would like to know if I have enough information to calculate the free energy.
If anyone could please point me in the right direction, I would appreciate it. I can't find anything online and maybe that's because I don't even know where to start looking. The sum of the potential and kinetic energies is the internal energy, E (or U).
However, you don't necessarily need to know the entropy to calculate the free energy. If you perform an equilibrium molecular dynamics simulation, you can derive the free energy from the equilibrium constant.
See, for instance:
https://onlinelibrary.wiley.com/doi/full/10.1002/jcc.21776
If you are modeling a constant T and V system, where there is no work done, the equilibrium constant would give you the Helmholtz free energy:
$$\Delta A = - R T ln K^{'}_{eq}$$
where A = E - TS
If you are modeling a constant T and p system, where you have no non-pV-work, the equilibrium constant would give you the Gibbs free energy:
$$\Delta G = - R T ln K^{''}_{eq}$$
where G = H - TS = E + pV - TS
The reason for this is that, at constant T and V, with no work term, minimizing A_sys corresponds to a maximization of S_univ, and thus determines the equilibrium condition. By contrast, at constant T and p, with pV-work only, minimizing G_sys corresponds to a maximization of S_univ, and thus determines the equilibrium condition.
I've marked the equilibrium constants as prime and double-prime to indicate that these would be numerically different.
The following is multiple choice question (with options) to answer.
Gibbs free energy values can be used to determine what? | [
"equilibrium differentials",
"prime constants",
"equilibrium constants",
"equal lines"
] | C | Gibbs free energy values can be used to determine equilibrium constants. |
SciQ | SciQ-7173 | fluid-dynamics, pressure, fluid-statics, thought-experiment
at a local level, the random motion of particles is the cause of pressure,
Random motion of particles is measured by temperature; the higher the temperature, the more intense the random motion.
If we are to talk about causes, the cause of pressure on some wall is first and foremost mutual interaction of the particles and the wall. The fact that the particles move randomly is secondary. True, in gases increase of pressure often goes with increase in this random motion, because the increase of gas pressure can be done only by putting in substantial energy. But in liquids, it is possible to increase the pressure substantially with negligible amount of work and so with negligible change in intensity of this random motion.
Pressure of such liquid is due to force interaction of the particles with walls and each other, not necessarily due to their random motion. It suffices that particles push or pull each other. They do not have to move rapidly. You can have high pressure in very cold water or in ice cold at 1 K.
When pressure of a liquid water is increased, say, by moving a piston in a blocked syringe filled with water, water temperature increase is very small and is usually neglected.
Now to your question - gravity isn't necessary for pressure either. What is necessary to increase pressure is some other body that will squeeze the gas or liquid into smaller volume. On Earth, this body is the Earth with its gravity, but the same pressure is achieved in a closed vessel, such as the International Space Station, simply by making it robust enough to withstand the pressure and pushing in enough amount of gas. There is no effective gravity there, but there is pressure close to 100kPa, due to walls not allowing the gas to escape.
The following is multiple choice question (with options) to answer.
Creep, which usually takes place where the ground freezes and thaws frequently, involves movement of particles due to what force? | [
"wind",
"friction",
"gravity",
"normal"
] | C | Creep usually takes place where the ground freezes and thaws frequently. Soil and rock particles are lifted up when the ground freezes. When the ground thaws, the particles settle down again. Each time they settle down, they move a tiny bit farther down the slope because of gravity. |
SciQ | SciQ-7174 | botany, entomology
Title: What is this small white insect on my plants? Environment
I have a large amount of plants in an old industrial loft apartment.
I live in Rochester, New York.
I ship plants in from across the US, often exotic ones.
Observations
A few months ago, I noticed that two of my Sarracenia plants in my carnivorous plant bog were not growing anymore. Upon cutting them out as to not disrupt the live sphagnum moss grow medium, I noted that one of the insects in question had burrowed its way down into the core of the plant. I assume this to be the cause of the growing issue.
Today I noticed that one of my grape plants and Colocasia plants were covered in these bugs at different stages of growth. They range from white specs to ~3mm with the tail thing.
These insects appear sedentary. I have never seen one move, except when I cut the one out of the center of the plant.
Here is a picture of the bug, which was difficult to get due to the size.
Research
I looked through a variety of different "common insect" sites as well as some insect identification sites but I was unable to find anything remotely similar.
I have only elementary knowledge of insects. Any pointers in the right direction would be appreciated. Mealybug; don't know much about them.
The following is multiple choice question (with options) to answer.
Which parasite causes downy mildew in grape plants? | [
"plasmopara viticola",
"chrysomyxa ledi",
"taphrina confusa",
"epichloe typhina"
] | A | Plant Parasites Protist parasites of terrestrial plants include agents that destroy food crops. The oomycete Plasmopara viticola parasitizes grape plants, causing a disease called downy mildew (Figure 13.18a). Grape plants infected with P. viticola appear stunted and have discolored withered leaves. The spread of downy mildew caused the near collapse of the French wine industry in the nineteenth century. |
SciQ | SciQ-7175 | classical-mechanics, lagrangian-formalism, coordinate-systems, constrained-dynamics, displacement
An approximate displacement ascribed to an interval of time $\Delta t$ is
$$\Delta {\bf x}_i = {\bf v}_i(t)\Delta t = \sum_{k=1}^n \frac{\partial {\bf x}_i}{\partial q^k}\frac{dq^k}{dt}\Delta t + \frac{\partial {\bf x}_i}{\partial t}\Delta t\:,$$
which can be rephrased to
$$\Delta {\bf x}_i = \sum_{k=1}^n \frac{\partial {\bf x}_i}{\partial q^k}\Delta q^k + \frac{\partial {\bf x}_i}{\partial t}\Delta t\:. \tag{4}$$
This identity has to be compared with the definition of virtual desplacement
$$\delta {\bf x}_i = \sum_{k=1}^n \frac{\partial {\bf x}_i}{\partial q^k}\delta q^k\:.$$
Even if we choose $\delta q^k = \Delta q^k$, the right-hand sides are different in view of the term $ \frac{\partial {\bf x}_i}{\partial t}\Delta t$ which accounts for a part of the displacement, in real motion, due to the fact that constraints may depend on $t$ explicitly, as in the example above.
The following is multiple choice question (with options) to answer.
What property is defined as the magnitude or size of displacement between two positions? | [
"passing",
"gravity",
"distance",
"Distance"
] | C | Distance Although displacement is described in terms of direction, distance is not. Distance is defined to be the magnitude or size of displacement between two positions. Note that the distance between two positions is not the same as the distance traveled between them. Distance traveled is the total length of the path traveled between two positions. Distance has no direction and, thus, no sign. For example, the distance the professor walks is 2.0 m. The distance the airplane passenger walks is 4.0 m. Misconception Alert: Distance Traveled vs. Magnitude of Displacement It is important to note that the distance traveled, however, can be greater than the magnitude of the displacement (by magnitude, we mean just the size of the displacement without regard to its direction; that is, just a number with a unit). For example, the professor could pace back and forth many times, perhaps walking a distance of 150 m during a lecture, yet still end up only 2.0 m to the right of her starting point. In this case her displacement would be +2.0 m, the magnitude of her displacement would be 2.0 m, but the distance she traveled would be 150 m. In kinematics we nearly always deal with displacement and magnitude of displacement, and almost never with distance traveled. One way to think about this is to assume you marked the start of the motion and the end of the motion. The displacement is simply the difference in the position of the two marks and is independent of the path taken in traveling between the two marks. The distance traveled, however, is the total length of the path taken between the two marks. |
SciQ | SciQ-7176 | 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.
Endosperm usually develops before the what does? | [
"embryo",
"nucleus",
"fetus",
"gamete"
] | A | |
SciQ | SciQ-7177 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What is the term for geological activity that occurs within a plate? | [
"intraplate activity",
"perennials activity",
"disruption activity",
"deformation activity"
] | A | Not all geological activity is found at plate boundaries. Activity within a plate is called intraplate activity. Most intraplate activity occurs at hotspots. |
SciQ | SciQ-7178 | } } { 3 } 3 s 3 3 \frac { {! Is: a 3-sided polygon sometimes ( but not very commonly ) called the trigon P Q! Note that the variables used are in reference to the triangle of these points...
The following is multiple choice question (with options) to answer.
What is a three-dimensional anticline called? | [
"volcano",
"dome",
"cyclone",
"cave"
] | B | In an anticline, rocks arch upward. A three-dimensional anticline is a dome. |
SciQ | SciQ-7179 | energy, dimensional-analysis, power, action
Title: Energy, power and action Through unit analysis, one can identify the following relationship linking energy, action and power:
$$\mathrm{energy\ ^2 = action \times power}.$$
Alternatively, we rewrite this expression as:
$$\mathrm{power = \frac{energy^2}{action}};$$
or
$$\mathrm{action = \frac{energy^2}{power}}.$$
In light of this tight relationship, it seems odd that physicists prefer only to discuss energy and action when it comes to quantum field theory. It would seem that the inverse relationship between action and power would lead to an alternative formulation where the goal is to find extremum of power instead of action. So why is there very little discussion of power in physics? we say that your formulae are "dimensionally correct", but that's it. They're dimensionally correct for a simple reason: energy is expressed in Joules which is the geometric average of Joule.seconds, the units of action, and Joules per second, the units of power.
But if you can construct an equation that is dimensionally correct, it doesn't yet mean that it is a correct identity - and it is very far from being a demonstrably useful one. I can't imagine any sensible context in which if would be true that "energy squared equals action times power". Moreover, even if such an identity existed, there could be a numerical coefficient, and it is pretty unlikely that it would be one.
So you're just playing with units - and yes, the left hand side has the same unit as the right hand side. That's a necessary condition but not a sufficient one for an equation to be OK. For such an equation to make sense, you must actually know "power of what", "energy of what", and "action of what" you are inserting into the equation. Otherwise you don't know what you're doing.
The following is multiple choice question (with options) to answer.
Electrical energy consumed can be expressed as the product of power multiplied by what else? | [
"energy",
"time",
"work",
"speed"
] | B | Electrical energy consumed can be determined by multiplying power by time . Recall the equations for mechanical and thermal energy/work . An important idea is the efficiency of an electrical device: the fraction of electrical energy consumed that goes into doing useful work , expressed as a percentage. |
SciQ | SciQ-7180 | pharmacology, blood-brain-barrier
One technology for enabling active transport of small molecule drugs
across the BBB involves targeting endogenous nutrient transporters.
These transporters are members of the solute carrier (SLC) transporter
superfamily. Transport of small molecules across the BBB by these
membrane proteins is known as carrier-mediated transport (CMT).
In order to design drugs that utilize CMT to cross the BBB,
researchers modify their chemical structures so that they resemble
nutrients that are transported across the BBB by specific SLCs. The
prototypical drug that uses this strategy (which was developed long
before mechanisms of CMT were known) is L-DOPA, the major current drug
for Parkinson's disease. L-DOPA is used to replace dopamine that is
lost due to degeneration of dopaminergic neurons in the substantia
nigra of the brain.
Another major system that is used in normal mammalian physiology to
enable needed molecules to cross the BBB is receptor-mediated
transport (RMT). The brain uses RMT to transport proteins, peptides,
and lipoproteins that are needed for brain function across the BBB.
Examples of biomolecules that are transported into the brain via RMT
include insulin, insulin-like growth factor (IGF), leptin,
transferrin, and low-density lipoprotein (LDL).
In RMT, molecules in the circulation may bind to specific receptors on
the luminal surface of brain capillaries (i.e., the surface that
interfaces with the bloodstream). Upon binding, the receptor-ligand
complex is internalized into the endothelial cell by a process called
receptor-mediated endocytosis. The ligand may then be transported
across the abluminal membrane of the endothelial cell (i.e., the
membrane that interfaces with brain tissue) into the brain. This whole
process is called receptor-mediated transcytosis.
The following is multiple choice question (with options) to answer.
What is the name for a substance that can be used to follow the pathway of that substance through some structure? | [
"tracker",
"solution",
"gel",
"tracer"
] | D | Learn some applications of radioactivity. Radioactive isotopes have a variety of applications. Generally, however, they are useful because either we can detect their radioactivity or we can use the energy they release. Radioactive isotopes are effective tracers because their radioactivity is easy to detect. A tracer is a substance that can be used to follow the pathway of that substance through some structure. For instance, leaks in underground water pipes can be discovered by running some tritium-containing water through the pipes and then using a Geiger counter to locate any radioactive tritium subsequently present in the ground around the pipes. (Recall that tritium is a radioactive isotope of hydrogen. ) Tracers can also be used to follow the steps of a complex chemical reaction. After incorporating radioactive atoms into reactant molecules, scientists can track where the atoms go by following their radioactivity. One excellent example of this is the use of carbon-14 to determine the steps involved in. |
SciQ | SciQ-7181 | human-biology, physiology, endocrinology, vitamins, homeostasis
Title: Counterintuitive action of Vitamin D? Vitamin D acts in a way which to me is counterintuitive. It functionally supplemets Parathormone. It in the intestinal tract steps up calcium absorption by altering nuclear gene expression and also prevents calcium excretion in kidneys. All of this is understandable. But it also, like parathormone, steps up osteoclast action in bone (actually steps up both osteoclast and osteoblast, but the osteoclast action is increased more to result in net bone resorption). This means that Vitamin D increases blood calcium level by increasing bone resorption.
Then how does Vitamin D help in improving bone density, bone strength and prevent rickets or osteoporosis? All of these would require bone deposition rather than resorption. There are two pieces to this question:
a) How does bone resorption (movement of Ca/Phos out of bone into the blood) result in net improvement in bone structure?
Bones are constantly remodeling, primarily in response to mechanical stressors. Although you clearly already realize this, I will make it explicit: osteoblasts are the cells that create new bone; osteoclasts break down (resorb) bone.
Quoting Harrison’s Internal Medicine1:
Radioisotope studies indicate that as much as 18% of the total skeletal calcium is deposited and removed each year. Thus, bone is an active metabolizing tissue.…The cycle of bone resorption and formation is a highly orchestrated process carried out by the basic multicellular unit, which is composed of a group of osteoclasts and osteoblasts
The following is multiple choice question (with options) to answer.
What do osteoclasts do to bone? | [
"break it down",
"build it up",
"strengthen it",
"lengthen it"
] | A | Under the direction of osteocytes, osteoblasts continuously build up bone, while osteoclasts continuously break down bone. These processes help maintain mineral homeostasis. |
SciQ | SciQ-7182 | food, decomposition
Title: Worm compost cannot have cooked food I live in the Netherlands and it is getting fashionable to compost with worms. After investigating a few websites I noticed that most websites suggested that I cannot feed the worms leftovers from citrus fruits. This seems logical. I then started noticing that people advise against feeding the worms cooked food.
I'm no biologist but I cannot imagine a reason why cooked food is bad for the worms. Could anybody explain why this might be in layman’s terms? There are a few reasons for not feeding cooked foods to worms (Eisenia spp.) in a smaller household size worm farm. It's not because the food is cooked but what it often contains.
The earthworm used in vermiculture is usually Eisenia fetida (red wigglers) though other Eisenia species are sometimes used. All Eisenia are epigeic species meaning they live in the junction of decomposing organic matter (such as leaf litter, aging manure, rotted fallen trees) and their natural food is decaying plant matter and bacteria that are also digesting the organic matter. They don't make use of small dead animals (meat and fat).
In large scale commercial vermiculture operations, leftover and past-due-date foods from restaurants, institutions, nursing homes and schools are used along with plant matter and carboard and paper. I'm not sure how they balance cooked foods but possibly much less is used than plant matter.
The fact food is cooked isn't the problem but what's in it and/or what happens to it when added to the bin. If you have leftover vegetables and fruit that's been cooked with no added salt, it's perfectly acceptable. A certain amount of sweetened cooked fruit is also fine as the worms will eat that too. But ready-made foods usually have preservatives, salt, fats and spices added. Either worms won't eat it, leading to odour caused by mouldy rotten food, or it can make them unthrifty and even killing off your worms if it's fed them repeatedly.
The following is multiple choice question (with options) to answer.
What do tube worms rely on for food? | [
"chemosynthetic microorganisms",
"lentiviruses microorganisms",
"fatty microorganisms",
"sponges microorganisms"
] | A | These brilliant red “feathers” are actually animals called tube worms. They live in an extreme environment on the deep ocean floor, thousands of meters below the water’s surface. Their world is always very cold and completely dark. Without sunlight, photosynthesis is not possible. So what do organisms eat at these depths? Tube worms depend on chemosynthetic microorganisms that live inside them for food. In this and other ways, tube worms have adapted to the extreme conditions of their environment. |
SciQ | SciQ-7183 | cell-biology
Title: Structure of Cell Are cells spheres or ovals/circles bound by phospholipidbilayer?
If they are spherical how are we able to see the nucleus through the phospholipid bilayer under a microscope? Not exactly. That is a stereotype of cells. Muscle cells are not round nor oval, but rather elongated rods. If you were to look up epithelia cells, you can quickly see that cells are grouped based on their physical characteristics; simple (round/oval & single layer), columnar, and cuboidal to name a few. Cells come in many shapes and sizes. As Hans stated, stains are vital in viewing cellular components. There is a diverse amount of stains used - which all carry a purpose and benefit in a specific application.
The following is multiple choice question (with options) to answer.
Size is a general feature of cell structure that relates to? | [
"timing",
"activation",
"instance",
"function"
] | D | |
SciQ | SciQ-7184 | meteorology, atmosphere
Title: Why do cities at high altitude regions have high atmospheric pressures? Why do cities at high altitude regions, such as Lhasa, altitude 11995ft (3656 metre), have high atmospheric pressures such as 30.11inHg (101.97 kPa) in the weather report? The reason for this is that the reported value is the relative pressure and not the absolute pressure. If meteorological stations reported the absolute pressure, dependent on elevation, it would been really confusing. So air pressure is always adjusted to sea level.
This is also why your home barometer has to be adjusted to show the correct pressure depending on the altitude where you are.
Here are a link to the weather close to where I live. It is at 150 m elevation,
https://www.yr.no/place/Norway/Buskerud/R%c3%b8yken/B%c3%b8dalen/hour_by_hour_detailed.html?spr=eng If you seek for Drammen you will see the green line showing the same pressure but the elevation there is close to sea level 10m or so.
The following is multiple choice question (with options) to answer.
Altitude is height above what? | [
"the water table",
"sea level",
"the earth's core",
"the earth's surface"
] | B | Altitude is height above sea level. The density of air decreases with height. There are two reasons. At higher altitudes, there is less air pushing down from above. Also, gravity is weaker farther from Earth's center. So at higher altitudes, air molecules can spread out more. Air density decreases. You can see this in Figure below . |
SciQ | SciQ-7185 | homework, ecology, population-biology, conservation-biology
Title: Difference between biological control and introducing species for conservation? I have a biology assignment and we have to explain various methods and strategies for conservation, two of which are:
Biological control
Introduced Species
What is the difference between these? I was under the impression that they are essentially the same thing – biological control being the introduction of species to predate pests (eg. the abysmal failure of the cane toad).
Any clarification would be great. After talking to my teacher, he said that biological control is the introduction of species to control another species, however species may be introduced for other reasons (the "Introduced Species" method), such as to "assist an ecosystem cope, flourish or re-establish itself."
The example he gave was the introduction of South African veldt grass to Western Australia in order to stabilise sand dunes, so that they can later be built upon further (eg. plants which may not perform well in sandy, unstable soil can then be planted).
Hopefully this helps anyone else with the same problem.
The following is multiple choice question (with options) to answer.
Conservation of what property of ecosystems is the aim of measures like the endangered species act? | [
"Allopatric speciation",
"biodiversity",
"bioremediation",
"natural selection"
] | B | Conservation of Biodiversity The threats to biodiversity at the genetic, species, and ecosystem levels have been recognized for some time. In the United States, the first national park with land set aside to remain in a wilderness state was Yellowstone Park in 1890. However, attempts to preserve nature for various reasons have occurred for centuries. Today, the main efforts to preserve biodiversity involve legislative approaches to regulate human and corporate behavior, setting aside protected areas, and habitat restoration. Changing Human Behavior Legislation has been enacted to protect species throughout the world. The legislation includes international treaties as well as national and state laws. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) treaty came into force in 1975. The treaty, and the national legislation that supports it, provides a legal framework for preventing “listed” species from being transported across nations’ borders, thus protecting them from being caught or killed in the first place when the purpose involves international trade. The listed species that are protected to one degree or another by the treaty number some 33,000. The treaty is limited in its reach because it only deals with international movement of organisms or their parts. It is also limited by various countries’ ability or willingness to enforce the treaty and supporting legislation. The illegal trade in organisms and their parts is probably a market in the hundreds of millions of dollars. Within many countries there are laws that protect endangered species and that regulate hunting and fishing. In the United States, the Endangered Species Act was enacted in 1973. When an at-risk species is listed by the Act, the U. Fish & Wildlife Service is required by law to develop a management plan to protect the species and bring it back to sustainable numbers. The Act, and others like it in other countries, is a useful tool, but it suffers because it is often difficult to get a species listed, or to get an effective management plan in place once a species is listed. Additionally, species may be controversially taken off the list without necessarily having had a change in their situation. More fundamentally, the approach to protecting individual species rather than entire ecosystems (although the management plans commonly involve. |
SciQ | SciQ-7186 | geology
Title: Where do riverbed stones come from? Have they always been here since the river was formed? Are some newer than others? Riverbed 'stones' - I assume you mean things like pebbles, boulders, etc. are pieces of rock that have weathered out and been deposited in the river. Some come from rock that is very close to where they are located and some have been transported from very far away. In general (and it is a very broad generalization) the rounder the stone, the longer it has been in the river and the more likely it is to have come from far away. Of course that depends on the hardness of the rock, and other factors, too.
Some rocks are newer than others. Some have been formed quite recently and some are billions of years old.
The following is multiple choice question (with options) to answer.
Nearly all rocks are made of what? | [
"magma",
"minerals",
"sand",
"calcium"
] | B | Nearly all rocks are made of minerals. A few are made of materials that do not fit the definition of minerals. |
SciQ | SciQ-7187 | biochemistry, physiology, cell-biology
Title: What triggers meiosis in gonadal cells? What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
What specific biochemical processes are involved in inducing meiosis rather than mitosis?
It's a difficult question because every step in the development of a germ cell is ultimately necessary for the final differentiation, which includes a meiotic division. Meiosis requires a lot of specialized components to pair and segregate homologues, to induce and resolve recombination, etc. What starts it all is still largely unknown. There are plenty of mutants that halt the process, but these are required along the way, so damaging the pathway ultimately stops it from progressing. At least one study has been able to initiate the program of meiosis in yeast:
Induction of meiosis in Saccharomyces cerevisiae depends on conversion of the transcriptional represssor Ume6 to a positive regulator by its regulated association with the transcriptional activator Ime1. I Rubin-Bejerano, S Mandel, K Robzyk, and Y Kassir
Basically, they turned on a transcription factor, which activated an entire suite of downstream genes necessary for meiosis. In essence, they turned on the "meiosis pathway." Bear in mind this is yeast, so does't have separate germ cells, but the concept is probably the same.
Why are gonadal cells the only cells in the human body which do undergo meiosis?
All other cells are diploid. Only in germ cells does the organism induce reductional divisions (to make haploid gametes for ultimate fusion in the zygote of the next generation). Creation of haploid somatic cells would uncover recessive lethal mutations and cells would die. In sperm and eggs, which do not express any genes until after fertilization and karyogamy, this is not a problem.
The following is multiple choice question (with options) to answer.
What type of cell division produces gametes? | [
"meiosis",
"mutations",
"mitosis",
"apoptosis"
] | A | Sexual reproduction involves two parents. As you can see from Figure below , in sexual reproduction, parents produce reproductive cells—called gametes —that unite to form an offspring. Gametes are haploid cells. This means they contain only half the number of chromosomes found in other cells of the organism. Gametes are produced by a type of cell division called meiosis, which is described in detail below. The process in which two gametes unite is called fertilization . The fertilized cell that results is referred to as a zygote . A zygote is diploid cell, which means that it has twice the number of chromosomes as a gamete. |
SciQ | SciQ-7188 | human-anatomy
Title: Difference between Appendix and the Cecum? What's the difference between an appendix and a cecum, and what are their functions? In herbivores the Cecum is an area that stores plant matter and helps digest it via symbiotic bacteria. Carnivores have smaller Cecums because meat is easier to digest than plant matter. In humans the Cecum is also an anatomical landmark that delineates the change from small intestine (a digesting organ) to the large intestine (mostly a capacity/storage organ).
The Appendix is a small, previously thought "superfluous" fleshy worm-shaped organ at the junction between the small and large intestines. Recent research posits that the appendix is sort of a harbor for a person's gut flora that can re-populate the intestines should the existing bacteria die or get removed (diarrhea being the most common cause). It can also become infected, inflamed, and require surgery to remove (Appendicitis).
The following is multiple choice question (with options) to answer.
Where are feces formed? | [
"duodenum",
"small intestine",
"liver",
"large intestine"
] | D | 34.3 Digestive System Processes Digestion begins with ingestion, where the food is taken in the mouth. Digestion and absorption take place in a series of steps with special enzymes playing important roles in digesting carbohydrates, proteins, and lipids. Elimination describes removal of undigested food contents and waste products from the body. While most absorption occurs in the small intestines, the large intestine is responsible for the final removal of water that remains after the absorptive process of the small intestines. The cells that line the large intestine absorb some vitamins as well as any leftover salts and water. The large intestine (colon) is also where feces is formed. |
SciQ | SciQ-7189 | earthquakes, seismology, instrumentation, in-situ-measurements, diy
Title: Using accelerometer as a seismograph I'm using ADXL345 accelerometer with Raspberry Pi to build a seismograph. I've successfully hooked it up and can plot the accelerometer data in three axis. Is there any way to express these data in the form of the magnitude of an earthquake, of course, at the point of sensing? I know that it might be imprecise, but any representation would be helpful (e.g. Richter scale), and how to accomplish that. The magnitude of an earthquake is related to the total energy released, therefore to estimate it from a seismogram you need to know the distance to the source. In the case of the Richter scale for example, the relationship between magnitude and seismogram amplitude is defined for a standard distance.
If you have only one seismograph, you can not triangulate the location of the source (hypocenter). Therefore, you can not estimate the magnitude of a seismic event (Richter or moment magnitude).
But you can estimate the local seismic intensity of the event at the particular location of your instrument. With the accelerometer data you can easily measure the peak ground acceleration, that can be used to estimate the intensity in any of the existing scales. For example, the peak ground accelerations associated to each intensity level in the commonly used Mercalli intensity scale are:
Those g values would be easy to calculate with the accelerometer data and proper calibration constants.
Table taken from the Wikipedia page for peak ground acceleration
You might want to have a look at this question. There are some nice answers and references that you might find useful.
The following is multiple choice question (with options) to answer.
What measurement of the wave is used to determine the magnitude of an earthquake? | [
"diameter",
"height",
"length",
"width"
] | B | Seismograms contain a lot of information about an earthquake: its strength, length, and distance. Wave height is used to determine the magnitude of the earthquake. The seismogram shows the different arrival times of the seismic waves ( Figure below ). The first waves are P-waves since they are the fastest. S-waves come in next and are usually larger than P-waves. The surface waves arrive just after the S-waves. If the earthquake has a shallow focus, the surface waves are the largest ones recorded. |
SciQ | SciQ-7190 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
In a food chain, only about 10 percent of what passes to the next level? | [
"mineral",
"hydrogen",
"vitamins",
"energy"
] | D | At each level of a food chain, a lot of energy is lost. Only about 10 percent of the energy passes to the next level. Where does that energy go? Some energy is given off as heat. Some energy goes into animal wastes. Energy also goes into growing things that another consumer can't eat, like fur. It's because so much energy is lost that most food chains have just a few levels. There’s not enough energy left for higher levels. |
SciQ | SciQ-7191 | botany, toxicology
Title: How can a plant resist glyphosate (Roundup) herbicide? In my area, the most common weeds that strongly resists (N-(phosphonomethyl)glycine) (glyphosate) are the horseweed, or mare's tail, Conyza canadensis, and Canada thistle, Cirsium arvense There are several other weeds with similar resistance. I use the brand Roundup on jobs where a complete kill is necessary. However, I sometimes have to go through again, with glufosinate, to control these weeds. I'd prefer not to, as the glufosinate lingers much longer in the soil.
Glyphosate inhibits an enzyme used in the synthesis of the aromatic amino acids tryptophan, tyrosine, and phenylalanine. It is taken in by the stomata in the leaves, and is moved throughout the plant to all the points of growth, acting fastest on those plants which are undergoing fastest growth.
I can't seem to find an article on how the weeds mentioned can tolerate this treatment. How do these weeds resist the glyphosate? I found a paper investigating the mechanism of glyphosate resistance in Conyza canadensis. They used 31P NMR to investigate the fate of the glyphosate in vivo. What they found is that the resistant plants are able to transport glyphosate into the vacuole:
The following view of horseweed resistance to glyphosate emerges from
the data presented herein. Glyphosate enters the cytoplasm of both R
and S plant variants at the same rate. Within hours, however,
glyphosate begins to occupy the vacuole in the R but not the S
biotype. The identical pH values of R and S vacuoles speak against the
possibility of a pH-driven process. This, coupled with the
preferential movement of glyphosate from the cytosol to the vacuole in
R tissue but not in S, suggests the presence of a transporter for
glyphosate either specific to R or at a substantially greater
concentration in R than in S tissue.
The following is multiple choice question (with options) to answer.
In plants, a high concentration of iaa inhibits what? | [
"cell elongation",
"technology elongation",
"Cell reproduction",
"same elongation"
] | A | the bottom of the cell. In roots, a high concentration of IAA inhibits cell elongation. The effect slows growth on the lower side of the root, while cells develop normally on the upper side. IAA has the opposite effect in shoots, where a higher concentration at the lower side of the shoot stimulates cell expansion, causing the shoot to grow up. After the shoot or root begin to grow vertically, the amyloplasts return to their normal position. Other hypotheses—involving the entire cell in the gravitropism effect—have been proposed to explain why some mutants that lack amyloplasts may still exhibit a weak gravitropic response. |
SciQ | SciQ-7192 | thermodynamics
Energy enters the body via the incident radiation; since it is a vacuum the only way for it to leave is through emitted radiation.
The fraction of the incident radiation which it absorbs is given by the emissivity $\varepsilon$. If the body is opaque, the remainder of the incident radiation is reflected. The amount of emitted radiation is determined by the Stefan-Boltzman law. So if the power per unit area of the incident radiation is $J$, then we have
$$\frac{\mathrm{d}E}{\mathrm{d}t} = A \varepsilon \left( J - \sigma T_H^4 - \sigma T_C^4 \right),$$
where $T_R$ is the temperature of the hot side of the plane (left in the figure) and $T_C$ is the temperature of the cold side. I am ignoring any possible wavelength-dependence of the emissivity.
To get equillibrium, set the time derivative of the energy to zero (i.e. make the rate of emission equal to the rate of absorption). Thus:
$$T_H^4 + T_C^4 = \frac{J}{\sigma}.$$
So far, the properties of the material haven't seemed to make a difference! ($\sigma$ is a universal constant, and the emissivity dropped out of the equation!) But where they enter is in determining the relationship between $T_C$ and $T_H$.
To determine the equillibrium relationship between these two temperatures, we must balance conduction from the hot side to the cold side against radiation from the cold side. Conduction in the body is described by the heat equation, which at equillibrium inside the slab gives a linear temperature profile, with the temperature decreasing linearly from $T_H$ to $T_C$.
The rate of heat conduction (per unit area) in this quasi-1d problem is
$$J_{\mathrm{conduction}} = \kappa \frac{\partial T}{\partial x} = \kappa \frac{T_H - T_C}{h},$$
The following is multiple choice question (with options) to answer.
The rate of heat transfer by radiation is largely determined by what? | [
"sound",
"scope",
"color",
"environment"
] | C | All objects absorb and emit electromagnetic radiation. The rate of heat transfer by radiation is largely determined by the color of the object. Black is the most effective, and white is the least effective. People living in hot climates generally avoid wearing black clothing, for instance (see Take-Home Experiment: Temperature in the Sun). Similarly, black asphalt in a parking lot will be hotter than adjacent gray sidewalk on a summer day, because black absorbs better than gray. The reverse is also true—black radiates better than gray. Thus, on a clear summer night, the asphalt will be colder than the gray sidewalk, because black radiates the energy more rapidly than gray. An ideal radiator is the same color as an ideal absorber, and captures all the radiation that falls on it. In contrast, white is a poor absorber and is also a poor radiator. A white object reflects all radiation, like a mirror. (A perfect, polished white surface is mirror-like in appearance, and a crushed mirror looks white. |
SciQ | SciQ-7193 | evolution, bioinformatics, sequence-analysis, methods, systems-biology
Title: Is there a system biology approach to compare pathways or famillies of proteins from an evolutionary point of view for the same organism? I would be interested to know if there is a method/analysis or a set of methods to compare two groups of pathways or families of proteins.
I would specifically be interested by a system biology approach which takes all the components of the pathway or family of proteins. I would like to know if there is a method which can not only compare the similarity, homology, divergence and convergence of a family of proteins (like ribosomal proteins) between species but also between groups in the same organism.
For example I would like to compare the molecular components of vesicular trafficking pathways to the molecular components of non-vesicular pathway in the same organism saccharomyces cerevisiae (yeast).
I would greatly appreciate your suggestions. I am not sure that I completely understand, it would be a little easier if you described the problem you are trying to solve or what the motivation is.
However, I think that some of what you want to do can be accomplished by inferring gene/protein trees for each gene/protein of interest across different species (including paralogs, maybe?). This will allow you to see discordance or correlation of evolutionary rates of different genes/proteins across species.
THis kind of analysis is built into HyPhy, though I have never used it. There are also somewhat less involved methods for measuring distances between trees.
You might also be interested in protein co-evolution methods, depending on the question at hand.
Your mentioning systems biology methods suggests that you have something rather different in mind, as none of these things I suggest are really systems biology IMO, but I'm not sure what it would be. Possibly you are interested in integrating e.g. protein-protein interaction or metabolic network information as well, but that would probably involve something more homebrewed that might integrate some of these things.
Hope that helps.
The following is multiple choice question (with options) to answer.
Comparisons of amino acid sequences can shed light on the evolutionary divergence of what? | [
"related species",
"mammals",
"birds",
"dinosaurs"
] | A | |
SciQ | SciQ-7194 | 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.
How high or low a sound seems is associated with what property of the sound? | [
"decibel",
"frequency",
"pitch",
"wavelength"
] | C | How high or low a sound seems to a listener is its pitch. Pitch, in turn, depends on the frequency of sound waves. |
SciQ | SciQ-7195 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
Alveolar ducts and broncioles are developing parts of what organ system? | [
"nervous",
"digestive",
"immune",
"respiratory"
] | D | Weeks 16–24 Once the respiratory bronchioles form, further development includes extensive vascularization, or the development of the blood vessels, as well as the formation of alveolar ducts and alveolar precursors. At about week 19, the respiratory bronchioles have formed. In addition, cells lining the respiratory structures begin to differentiate to form type I and type II pneumocytes. Once type II cells have differentiated, they begin to secrete small amounts of pulmonary surfactant. Around week 20, fetal breathing movements may begin. |
SciQ | SciQ-7196 | 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.
During photosynthesis what organelle is used by plants to change sunlight into chemical energy? | [
"mitochondria",
"ribosome",
"chloroplasts",
"golgi apparatus"
] | C | When ancient plants underwent photosynthesis, they changed energy in sunlight to stored chemical energy in food. The plants used the food and so did the organisms that ate the plants. After the plants and other organisms died, their remains gradually changed to fossil fuels as they were covered and compressed by layers of sediments. Petroleum and natural gas formed from ocean organisms and are found together. Coal formed from giant tree ferns and other swamp plants. |
SciQ | SciQ-7197 | water, mountains
Title: How do mountain springs get their water? I am curious how do mountain springs get their water. The water flowing from them eventually forms rivers.
Is it only from rain and snow? Or does water also come from underground-below the mountain (if so, then how does it "climb" to the spring which is at a high altitude)? Ultimately, it comes from precipitation. Ordinarily we think of rain as coming from low-level clouds, but Putkonen[1] has compiled rainfall data in the Himalayas showing significant rains up to several thousand meters altitude, covering the range where practically everyone lives. It is this precipitation that fills the underground tables mentioned by Jean-Marie Prival in a comment to the question.
Such a source is subject to the effects of climate change, which accordingly has led to significant environmental issues. See Ref [2].
References:
1.
Jaakko K. Putkonen, "Continuous Snow and Rain Data at 500 to 4400 m Altitude near Annapurna, Nepal, 1999–2001", Arctic, Antarctic, and Alpine Research, 36:2, 244-248 (2004)
2.
Sandeep Tambe, Ghanashyam Kharel, ML Arrawatia, Himanshu Kulkarni, Kaustubh Mahamuni, Anil K Ganeriwala,
"Reviving dying springs: climate change adaptation experiments from the Sikkim Himalaya",
Mountain Research and Development 32 (1), 62-72 (2012)
The following is multiple choice question (with options) to answer.
Small water bodies often fed by springs are called what? | [
"oceans",
"ponds",
"rivers",
"puddles"
] | B | Ponds are small water bodies often fed by springs. |
SciQ | SciQ-7198 | inorganic-chemistry
Title: Wood burning and carbon dioxide or monoxide? I am building greenhouse and i want to operate greenhouse at winter time. For heating i ll use wood. And also i am thinking to give back carbon monoxide which ll come from burning process of wood. There is a question, how can avoid to get carbon monoxide from burning wood, do i must give more air flow (or oxygen flow) to burning process? Or when you burn wood there is just one gas output that is carbon dioxide? A good reference to read is Laboratory and field investigations of particulate and carbon monoxide emissions from traditional and improved cookstoves Atmospheric Environment February 2009, Pages 1170–1181.
Unforntunately, there is a significant amount of carbon monoxide, from 29 to 118 grams of CO per kg of wood.
They find that the drier the wood, the less CO, but don't expect to completely eliminate CO.
The following is multiple choice question (with options) to answer.
The combustion of propane gas produces carbon dioxide and what else? | [
"methane",
"water vapor",
"carbon monoxide",
"phosphorous"
] | B | The combustion of propane gas produces carbon dioxide and water vapor. |
SciQ | SciQ-7199 | herpetology, poison
Title: Poisonous Snakes consuming poison (chemical) While travelling with my Son to a religious shrine, we saw a dead snake lying on the road.
My Son asked a curious question to me "Dad, if Poisonous snakes consume poison (Chemical), Will they die"?
I feel the answer is depends upon the type of poisonous snake viz Cobra, Python etc and how much the reptile has consumed the poison. i.e. quantity.
What is the correct answer? If any living thing consumes enough of a poison it will die. But I feel that is not what you want to ask.
Perhaps you meant to ask if a snake will die if it drinks its own venom? That would make more sense as a question.
In English, venom and poison mean different things when talking about a toxic chemical produced by an animal.
Poison is a toxic chemical produced by an animal that is meant to be ingested/eat/drink.
Venom is a toxic chemical produced by an animal that is meant to be injected into the bloodstream.
So a snake bite has venom, but a colourful tree frog has poison on its skin.
Venom is typically not nearly as harmful if ingested, even if by a different animal, because it is meant to act directly in the bloodstream
The following is multiple choice question (with options) to answer.
Tremetol, a metabolic poison found in the white snake root plant, prevents the metabolism of what? | [
"sugars",
"lipids",
"lactate",
"sodium"
] | C | Tremetol, a metabolic poison found in the white snake root plant, prevents the metabolism of lactate. When cows eat this plant, it is concentrated in the milk they produce. Humans who consume the milk become ill. Symptoms of this disease, which include vomiting, abdominal pain, and tremors, become worse after exercise. Why do you think this is the case? Alcohol Fermentation Another familiar fermentation process is alcohol fermentation ( Figure 7.15) that produces ethanol, an alcohol. The first chemical reaction of alcohol fermentation is the following (CO2 does not participate in the second reaction):. |
SciQ | SciQ-7200 | meteorology, atmosphere, carbon, co2, rain
Bear in mind that this assumes an enormous rainfall intensity, 100% CO2 saturation of the water and equilibrium chemical dynamics. After the raindrops hit the ground at least half of it will immediately re-evaporate back into the air, leaving, at absolute most, about 3% of the atmospheric CO2 leached out of the atmosphere that will be available to react with the soil, rock or biosphere. Also consider that this is but one of several important processes affecting CO2 transience, such as photosynthesis, respiration, volcanism, industrial pollution, etc. So the CO2 estimates that you read about are average values. Advection and turbulent air mixing should ensure that the CO2 regains approximately normal concentration within an hour or two after rainfall.
The following is multiple choice question (with options) to answer.
Water, carbon dioxide, and what other element are important agents of chemical weathering? | [
"methane",
"helium",
"sulfur",
"oxygen"
] | D | Water, carbon dioxide, and oxygen are important agents of chemical weathering. |
SciQ | SciQ-7201 | 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.
Deserts and forests are examples of what type of biome? | [
"acquatic",
"freshwater",
"abundant",
"terrestrial"
] | D | Terrestrial biomes , which are land-based, such as deserts and forests. |
SciQ | SciQ-7202 | species-identification, marine-biology
Title: help identify this fish
I came across this washed up fish in Panama City, Florida in November 2015. I'm guessing it's a puffer fish but I can't find anything like it online.
Thanks. This is a kind of trunkfish. (They have different names, this could be a smooth or spotted trunkfish.). It's really a lovely and comical little fish when observed alive in coral reefs. It has the ability to change its coloration depending on whether it's excited or calm, or to minimize its contrast to the background. It is related to puffer fish.
It has a boxy, triangular body shape, and propels itself with relatively tiny, delicate fins. Like pufferfish, they are toxin producers.
In death, the body shape and coloration are different, of course. Never saw a dead one before; sad. The juveniles are adorable:
Members of this family occur in a variety of different colors, and are notable for the hexagonal or "honeycomb" patterns on their skin. - Wikipedia
The following is multiple choice question (with options) to answer.
Lampreys use their sucker to feed on what part of other fish species? | [
"blood",
"brain",
"liver",
"heart"
] | A | Viruses are classified on the basis of several traits. For example, they may be classified by capsid shape, presence or absence of an envelope, and type of nucleic acid. Most systems of classifying viruses identify at least 20 virus families. Table below shows four examples of virus families and their traits. Have any of these viruses made you sick?. |
SciQ | SciQ-7203 | evolution, botany, ecology, plant-physiology, plant-anatomy
Title: Why do some plant species have lobed leaves, while similar species in the same habitat don't? Some plants have lobed leaves, like the English oak (Quercus robur), while other plants growing the same deciduous woodland habitats, and very often growing alongside oaks, such as the European beech (Fagus sylvaticus) don't have lobes. Here are two two leaves side by side for comparison:
These two species should be subject to most of the same evolutionary pressures. Why would one evolve lobed leaves, whilst the other has only tiny serrations? This is a question for which, I think at the moment, we don't have a clear answer.
It is important to bear in mind that the leaf plays a number of important roles in the plant (photosynthesis, thermoregulation etc.) so leaf shapes probably evolved through a process of successive trade-offs. This may make it difficult to identify the exact selection processes operating on any one species. In contrast, something like the eye has a well-defined single function, which in principle at least, makes it easier to understand the link between form and function.
From Niklas (1988):
Life history and optimisation theory suggest that the number of
phenotypic solutions that allow for different equally successful trait
combinations increases as the number of trade-offs increases – a
conclusion that applies to traits within the leaf (e.g. for shape) as
well as to leaf–branch relationships.
However, there are a number of ideas to explain leaf shape diversity which include:
Thermoregulation
It has been shown that by adding lobes to leaves, the rate of heat transfer across a leaf is greater than that of an unlobed leaf of the same area (e.g. Gurevitch and Schuepp 1990). So, lobed leaves may be selected for under certain environmental conditions.
hydromechanical constraints
Lobed leaves may have greater hydraulic efficiency. For smaller veins, hydraulic pressure increases as they present an increased resistance to water flow. This places stress on the deliate outer leaf tissues. If lobed leaves have relatively less mesophyll tissue than large, highly conductive veins, they may have reduced hydraulic resistance compared unlobed leaves (Sack and Tyree 2005).
The following is multiple choice question (with options) to answer.
Nonflowering vascular plants have how many basic types of leaves? | [
"one",
"five",
"three",
"four"
] | C | Leaves may vary in size, shape, and their arrangement on stems. Nonflowering vascular plants have three basic types of leaves: microphylls (“tiny leaves”), fronds , and needles . Figure below describes each type. |
SciQ | SciQ-7204 | human-biology, senses
Olfaction (smell, as carried out by neurons in the nasal epithelium; e.g. smell of vanilla, and smell of bad food)
Gustation (taste, as carried out by neurons on the tongue; e.g. salt, sugar)
Antigen chemosensing (chemical sensing, as carried out by, for instance, immune antigen receptors on B cells)
Hormonal signaling chemosensing (chemical sensing of hormones such as insulin, as carried out for instance by myocytes)
Starch sensing? (amylase in saliva can be used as a test for digestable starch)
Visual system, at the retina?
Visible light (sensing electromagnetic radiation on the order of a few hundred nanometers in wavelength)
Internal methanol sensing (the visual system as a sensor for methanol, which disproportionately affects myelin surrounding the optic nerve)
Pressure sensing (see phosphenes)
The vestibular system
Gravity sensing
Balance
Coordination
Motion sensor
Head position sensor
Spatial orientation
Skin
thermosensation (touching a hot kettle!)
Nociception (pain sensing)
allergen sensing
sensor for gamma rays, X-rays and UV light (indicated by radiation burns, development of skin cancer, sunburns, etc.)
Bones and muscles?
Kinesthetic and bodily proprioception
Brain/mind/mental/social senses?
mental pain
boredom
mental or spiritual distress
sense of self and other, including friendship, power, place in social hierarchy, reputation, companionship
motivation and love (oxytocin, dopamine, etc. in limbic systems and other neural correlates)
I'm sure some would agree, and some would disagree about the specific cases I provide. Thus the definition of senses, or sensing, seems to be opinion-based or at the very least very sensitive to an agreed-upon operational definition, for which there is none.
The following is multiple choice question (with options) to answer.
Somatosensation includes all sensation received from the skin and mucous membranes, as well as from these? | [
"limbs and joints",
"organs",
"glial cells",
"five senses"
] | A | 36.2 Somatosensation Somatosensation includes all sensation received from the skin and mucous membranes, as well as from the limbs and joints. Somatosensation occurs all over the exterior of the body and at some interior locations as well, and a variety of receptor types, embedded in the skin and mucous membranes, play a role. There are several types of specialized sensory receptors. Rapidly adapting free nerve endings detect nociception, hot and cold, and light touch. Slowly adapting, encapsulated Merkel’s disks are found in fingertips and lips, and respond to light touch. Meissner’s corpuscles, found in glabrous skin, are rapidly adapting, encapsulated receptors that detect touch, lowfrequency vibration, and flutter. Ruffini endings are slowly adapting, encapsulated receptors that detect skin stretch, joint activity, and warmth. Hair receptors are rapidly adapting nerve endings wrapped around the base of hair follicles that. |
SciQ | SciQ-7205 | 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.
What is the only class of animals that has hair? | [
"birds",
"mammals",
"amphibians",
"reptiles"
] | B | Only mammals have hair. Hair is a fiber made mainly of the tough protein keratin. The cells of each hair are filled with keratin and no longer alive. The dead cells overlap each other, almost like shingles on a roof. They work like shingles as well, by helping shed water from hair. |
SciQ | SciQ-7206 | physiology, muscles
Title: Does muscle get bigger by increase in size of individual cells or increase in number? Somewhere in the back of my mind, I have the claim that a muscle never increases its amount of cells but, if the muscle gets bigger, it's simply because individual cells get bigger.
The book Anatomy Trains on page 36 cites "Changes in sarcomere length and physiological properties in immobilized muscle by Williams et al" when it makes the claim :
Stretched, a muscle will attempt to recoil back to its
resting length before giving up and adding more cells
and sarcomeres to bridge the gap.
Is that true? Do muscles increase the number of their cells in that way? The "back of your mind" is correct: "if the muscle gets bigger, it's simply because individual cells get bigger."
Growth of muscle can occur in three ways:
by an increase in muscle cell numbers
by an increase in muscle fiber diameter
by an increase in fiber length.
However, growth in cell numbers is limited to the prenatal and immediately postnatal period, with the animals and man being born with or soon reaching their full complement of muscle cells.
[G]rowth occurs by either hypertrophy of the existing muscle fibers by adding additional myofibrils to increase the muscle mass or by adding new sarcomeres to the ends of the existing muscle fibers to increase their length. Both of these mechanisms occur during the growth process. Growth in the girth of the muscle fibers... may be stimulated by development of stress creating an unequal pressure with splitting at the Z-band and development of additional SR and T-tubule systems. This adds to the diameter or girth of myofibers without any hyperplasia. The growth in length occurs at either end of the fibers and results in addition of new sarcomeres. In both cases, new myofibrillar protein must be synthesized and deposited in the muscle cells.
The following is multiple choice question (with options) to answer.
What is the muscular organ that nourishes and supports the growing embryo? | [
"uterus",
"stomach",
"fallopian tube",
"ovary"
] | A | The Uterus and Cervix The uterus is the muscular organ that nourishes and supports the growing embryo (see Figure 27.14). Its average size is approximately 5 cm wide by 7 cm long (approximately 2 in by 3 in) when a female is not pregnant. It has three sections. The portion of the uterus superior to the opening of the uterine tubes is called the fundus. The middle section of the uterus is called the body of uterus (or corpus). The cervix is the narrow inferior portion of the uterus that projects into the vagina. The cervix produces mucus secretions that become thin and stringy under the influence of high systemic plasma estrogen concentrations, and these secretions can facilitate sperm movement through the reproductive tract. |
SciQ | SciQ-7207 | organic-chemistry, nomenclature
Title: Nomenclature of a cyclohexyl ether and locant position enumeration
As far as I know, 'ethoxy' should be given the locant '1' as it is a functional group. The compound should thus be named 1-ethoxy-2,2-dimethylcyclohexane.
However, I was told that the correct name is 2-ethoxy-1,1-dimethylcyclohexane. Can anyone please explain why this is so? My teacher explained this to me in terms of the lowest locant sum rule, which I just discovered doesn't even exist. The smallest sum of locants rule does not exist in the IUPAC recommendations. The application of this ‘rule’ can lead to wrong results in many instances.
The corresponding section in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book) actually reads as follows:
P-14.3.5 Lowest set of locants
The lowest set of locants is defined as the set that, when compared term by term with other locant sets, each cited in order of increasing value, has the lowest term at the first point of difference; for example, the locant set ‘2,3,5,8’ is lower than ‘3,4,6,8’ and ‘2,4,5,7’.
(…)
With regard to numbering of locants, simple prefixes (simple substituent groups consisting of just one part that describes an atom, or group of atoms as a unit, for example methyl and ethoxy) are considered together with equal seniority:
P-14.4 NUMBERING
When several structural features appear in cyclic and acyclic compounds, low locants are assigned to them in the following decreasing order of seniority:
(…)
(f) detachable alphabetized prefixes, all considered together in a series of increasing numerical order;
(…)
Therefore, the example is named as 2-ethoxy-1,1-dimethylcyclohexane rather than 1-ethoxy-2,2-dimethylcyclohexane since the locant set ‘1,1,2’ is lower than ‘1,2,2’.
The following is multiple choice question (with options) to answer.
The smallest cyclic ether is called what? | [
"quark",
"aldehyde",
"peroxidase",
"epoxide"
] | D | The smallest cyclic ether is called an epoxide. Draw its structure. |
SciQ | SciQ-7208 | pathophysiology, kidney
Title: To diagnose osteomyelitis of vertebral column in chronic kidney failure Assume you suspect amyloidosis because of the history of the patient: problem with vertebral column and "purulent" (serous, fibrous, or hemorrhagic) inflammation when patient very young.
Now, the patient has a chronic renal failure.
Is there any other method to diagnose the fracture of some bone than röntgen?
Assume you do not know where the fracture is exactly. Osteomyelitis can be diagnosed with the following imaging techniques [1]:
first of all: radiography to view the anatomy of the bone
the sonography can be used to diagnose fluid collections, periosteal involvement. It is also the most useful procedure for kidney assessment [2].
CT is also useful to detect early osseous erosion, but is less sensitive when it comes to bone infection
MRI is the most sensitive and specific for osteomyelitis
Nuclear imaging can be used to identify multifocal osseous involvement.
References:
Carlos Pineda et al., Radiographic Imaging in Osteomyelitis: The Role of Plain Radiography, Computed Tomography, Ultrasonography, Magnetic Resonance Imaging, and Scintigraphy
American College of Radiology, Renal failure
The following is multiple choice question (with options) to answer.
Dialysis is a medical process of removing wastes and excess water from the blood by diffusion and ultrafiltration. when kidney function fails, dialysis must be done to artificially rid the body of this? | [
"calories",
"mucus and phloem",
"waste and fluids",
"bile juices"
] | C | Dialysis Technician Dialysis is a medical process of removing wastes and excess water from the blood by diffusion and ultrafiltration. When kidney function fails, dialysis must be done to artificially rid the body of wastes and fluids. This is a vital process to keep patients alive. In some cases, the patients undergo artificial dialysis until they are eligible for a kidney transplant. In others who are not candidates for kidney transplants, dialysis is a lifelong necessity. Dialysis technicians typically work in hospitals and clinics. While some roles in this field include equipment development and maintenance, most dialysis technicians work in direct patient care. Their on-the-job duties, which typically occur under the direct supervision of a registered nurse, focus on providing dialysis treatments. This can include reviewing patient history and current condition, assessing and responding to patient needs before and during treatment, and monitoring the dialysis process. Treatment may include taking and reporting a patient’s vital signs, preparing solutions and equipment to ensure accurate and sterile procedures. |
SciQ | SciQ-7209 | biophysics, theoretical-biology, ecosystem
Systems ecology, especially with regard to energy and nutrient flow.
This type of ecology can be strongly influenced by physics. For one example see the book Theoretical Ecosystem Ecology: Understanding Element Cycles by Ågren & Bosatta (Ågren was originally a physicist)
Physical limitations to growth and transport
This can include for instance mechanical contraints on plant growth (see e.g. the book Plant Physics by Nicklas & Spatz), water transport in trees (see e.g. this BioSE question) or the biomechanics of movement (see e.g. Hudson et al (2012) on the speed and movement of cheetahs or Wikipedia: Biomechanics).
Allometric relationships between organisms, e.g. with regard to metabolism
To explain these types of relationships knowledge in physics is useful. See e.g. Kleiber's law for more.
MAXENT as a general approach to ecological patterns or to model species distributions
This is basically a tool lifted from physics that can be applied to ecological problems. There are many papers to look at, but Harte & Newman (2014) (Harte is another previous physicist) and Elith et al (2010) are two good starting points.
Dynamical modelling of populations and communities
This field use many of the same tools for analysis as physics, e.g. systems of differential equations. One of the pioneers in this field (among many) were Robert May (also started with a PhD in physics), and his classical book Theoretical Ecology: Principles and Applications is still a good starting point.
Energy harnessing and conversion by organisms
This can refer both to how organsims convert prey to energy (e.g. conversion efficiencies) and the physics of photosynthesis (which is an interesting intersection between physics and molecular biology). See Jang et al (2004) and O'Reilly & Olaya-Castro (2013) for examples of the how quantum mechanics can inform us about photosynthesis.
Hopefully this will give you a sense of some different ways that knowledge in physics can be useful for biology.
The following is multiple choice question (with options) to answer.
What is the study of how living things interact with each other and with their environment? | [
"biology",
"ecology",
"geology",
"scientology"
] | B | Ecology is the study of how living things interact with each other and with their environment. |
SciQ | SciQ-7210 | electrostatics, electricity, electric-current, charge, flow
Title: Why does the flow of charge even create electricity? Okay this is a question I’ve asked a lot of places but I always get its the flow of charges and it’s like a property. What I don’t really understand is how is this flow of charges creating electric current.
My guess is that as these charges get closer to the desired potential(to satisfy potential difference) Energy is released which happens continuously and it is the reason for electric current atleast in a conductor.
Can I get some insight into what is happening down at the quantum level. First of all you have to understand that flow of electrical current and dissipation of energy are two completely different concepts.
Electrical current: The flow of electrical charges is called electrical current. This is like a definition and has nothing to do with dissipation. There are systems, where current flows without dissipation. At the elementary level, you get the electrical current $I$, if you count, how many elementary charges $e$ cross a specific cross-sectional area of your "conductor" per second. Mathematically this means:
$$ I := \frac{e\Delta N}{\Delta t},$$
where $I$ is the current, $\Delta t$ is the time interval (e.g. 1 second), $e$ is the elementary charge, and $\Delta N$ is the number of elementary charges that you count within time $\Delta t$.
Usually, conductors are metals, and you may think of the cross sectional area of a copper wire, for example. But you can also imagine other "conductors" that are liquids with ions in them, or even gases with charged atoms in them.
Electrical resistance: Flowing charge carriers dissipate energy, if they scatter with other particles and thereby lose energy. In metals, for example, electrons forming the electrical current will scatter from lattice vibrations (phonons) and thereby dissipate energy. This energy dissipation leads to electrical resistance, usually denoted by $R$.
The following is multiple choice question (with options) to answer.
What is a continuous flow of electric charge called? | [
"microwave current",
"magnetism",
"powered current",
"electric current"
] | D | Electric current is a continuous flow of electric charge. It is measured in amperes (A). Direct current (DC) flows in just one direction. Alternating current (AC) keeps reversing direction. |
SciQ | SciQ-7211 | geochemistry, earth-history, co2, carbon-cycle
Source: Wikimedia Commons.
I heard this argument at the University of Zaragoza. However, I am uncertain if both my teacher and I have a comprehensive understanding of this matter. One of my concerns is that CO2 dissolves below the Calcite Compensation Depth. I'm unsure if all sediments dissolve or just the top layers. This uncertainty leaves me pondering whether my argument could be refuted on this basis. I couldn't find any clarifications on Science Direct either.
Could someone elucidate this matter for both my friend (who will read this) and me?
Are the Phanerozoic CO2 levels indeed linked with the Wilson Cycle? If so, why?
Bonus Question:
If humans wouldn't exist, would we run out of CO2? (To me, this seems like an absurd query, especially in the context of that Nobel Prize article, because we'll likely gain control over Earth's geochemistry and climate long before then.) To rephrase: if we exclude human influence, would shell organisms eventually consume all the CO2 by the end of the Phanerozoic era, leading to a mass extinction and the emergence of a distinct form of life? Would this scenario transpire in this cycle or the next? On geological timescales, yes, the Wilson cycle (opening and closing of ocean basins) is bound to have an effect on atmospheric CO2 levels, if only because it will affect rainfall patterns, which in turn will affect chemical weathering of rocks, which is one of the things that removes CO2 from the air on very long timescales.
This obviously doesn't explain the post-industrial rise in atmospheric CO2 though, which has occurred on the scale of a century or so, rather than tens to hundreds of millions of years. So it seems like a grain of truth, but the argument is a non-sequitur.
"In the forthcoming million years, CO2 stored by organisms will be
released."
The following is multiple choice question (with options) to answer.
How many years can dissolved carbon be stored in the deep ocean? | [
"unknown",
"thousands",
"tens",
"hundreds"
] | B | Water erosion by runoff, rivers, and streams dissolves carbon in rocks and carries it to the ocean. Ocean water near the surface dissolves carbon dioxide from the atmosphere. Dissolved carbon may be stored in the deep ocean for thousands of years. |
SciQ | SciQ-7212 | newtonian-mechanics, fluid-dynamics, coriolis-effect
Title: Circular Winds and Coriolis force
In northern hemisphere the flow of air is shown which tries to move towards low pressure center but due to Coriolis is deflected as shown.
It's said that this causes a circular anticlockwise flow of air.
How's that?
The air will just try to move in and get deflected as shown and curve away, how then will a circular pattern be formed? Once the wind reaches a velocity such that the Coriolis and pressure gradient forces balance, it continues at that velocity due to inertia. This state is called geostrophic flow and corresponds to wind along isobars.
For an intense localized low pressure like a hurricane, the flow is not geostrophic—the pressure gradient force is larger in magnitude than the Coriolis force, maintaining the inward net acceleration required for circular motion.
The following is multiple choice question (with options) to answer.
What effect causes winds and currents to form circular patterns? | [
"horse latitudes",
"jet stream",
"centrifugal effect",
"coriolis effect"
] | D | The Coriolis effect causes winds and currents to form circular patterns. The direction that they spin depends on the hemisphere that they are in. |
SciQ | SciQ-7213 | temperature, sun, light, equator, insolation
Title: Why does the intensity of sunlight depend on your latitude? People at the equator get to bask in more sunlight than Santa Clause and other inhabitants of the arctic regions. Not quite as pronounced, but they get more than me too.
Why is the sunlight more intense closer to the equator and less intense farther away from it?
When I posted this question, I was not thinking about the possible ambiguities, such as "Are you talking about the exposure across a surface area with some non-perpendicular angle to the sun," or "Are you talking about the light gathered by an optic facing the sun?" There is a difference. Since "basking in sunlight" was the example use case, let us assume exposure across a surface area which is lying on the ground. As noted in the comments, this answer applies to things like sun-bathing and solar panels, but it does not apply so much to a specific point-receptor like an eyeball. If all objects in question are pointing directly at the sun, then the angle of incidence is equal for all of them and this answer does not apply.
For an optic facing its target, the amount of atmosphere that the light passes through is a very large influencer. At higher latitudes, the sun is not directly overhead, and so the light is not coming straight down through the path of least atmosphere. Instead, it comes in at an angle, passing through more of the atmosphere before it gets to you.
For sun-bathers, solar panels, and the ground in general, the sunlight absorbed and reflected does depend very much on what is described in this answer. For that reason, more expensive solar panels are mounted on devices which alter their angle to face the sun for increased light exposure. And a sun-bather could likewise increase their exposure by mounting their platform at an angle. This is the direction the rest of the answer will take.
The answer is similar to the answer to some other questions, such as "Why does the solar power intensity change with the season?" and "Why does the solar intensity change with the height of the sun in the sky (ie: with the time of day)?"
The very short, non-technical version (tl;dr)
Each unit (think "beam of sunlight") is spread over a larger area.
That might not seem intuitive at first, but that is the answer in a nutshell. To see why, continue to the long version.
The following is multiple choice question (with options) to answer.
What type of sunlight inhibits vertical growth in a plant? | [
"direct",
"reduced",
"infrared",
"indirect"
] | A | |
SciQ | SciQ-7214 | phase-transition, biophysics, medical-physics, glass, amorphous-solids
313 6003 pp573-5 (1985).
This outcome was identified as early as the 1960s by electron microscopy of thawed cells, which revealed many puncture holes in the membrane.
Both freezing and rethawing are opportunities for damage, as recrystallization can occur during the latter regardless of how carefully the former was performed.
Freezing into the crystalline phase of ice (and many other materials) produces sharp dendrites because some crystal orientations exhibit very fast growth kinetics. This issue doesn't arise with amorphous freezing.
For an early discussion, see, for example, Mazur's "Cryobiology: the freezing of biological systems" Science 168 3934
pp939-49 (1970) and the references within.
The following is multiple choice question (with options) to answer.
Why does ice wedging occur? | [
"water freezes",
"water melts",
"water evaporates",
"water expands"
] | D | Ice wedging happens because water expands as it goes from liquid to solid. When the temperature is warm, water works its way into cracks in rock. When the temperature cools below freezing, the water turns to ice and expands. The ice takes up more space. Over time, this wedges the rock apart. Ice wedging is very effective at weathering. You can find large piles of broken rock at the base of a slope. These rocks were broken up by ice wedging. Once loose, they tumbled down the slope. |
SciQ | SciQ-7215 | human-biology, evolution, speciation, species, human-evolution
Is this definition incorrect?
Are the publications using "species" colloquially, as opposed to scientifically?
Is "species" still a poorly defined concept? (see Ring Species)
Thanks! Short answer
The concept of species is poorly defined and is often misleading. The concepts of lineage and clade / monophyletic group are much more helpful. IMO, the only usefulness of this poorly defined concept that is the "species" is to have a common vocabulary for naming lineages.
Note that Homo neanderthalis is sometimes (although it is rare) called H. sapiens neanderthalis though highlighting that some would consider neanderthals and modern humans as being part of the same species.
Long answer
Are neanderthals and modern humans really considered different species?
Often, yes they are considered as different species, neanderthals being called Homo neanderthalis and modern humans are being called Homo sapiens. However, some authors prefer to call neanderthals Homo sapiens neanderthalis and modern humans Homo sapiens sapiens, putting both lineages in the same species (but different subspecies).
How common were interbreeding between H. sapiens and H. neanderthalis
Please, have a look at @iayork's answer.
The rest of the post is here to highlight that whether you consider H. sapiens and H. neanderthalis to be the same species or not is mainly a matter of personal preference given that the concept of species is mainly arbitrary.
Short history of the concept of species
To my knowledge, the concept of species has first been used in the antiquity. At this time, most people viewed species as fixed entities, unable to change through time and without within-population variance (see Aristotle and Plato's thoughts). For some reason, we stuck to this concept even though it sometimes appears to not be very useful.
Charles Darwin already understood that as he says in On the Origin of Species (see here)
The following is multiple choice question (with options) to answer.
Are humans a new or old species on the earth? | [
"new",
"extinct",
"old",
"primal"
] | A | This timeline shows the history of life on Earth. In the entire span of the time, humans are a relatively new addition. |
SciQ | SciQ-7216 | photons, material-science, absorption, optical-materials, glass
There are further complications to all of this as well. Will the light undergo scattering processes that may allow the light to move through a material, while changing directions and potentially even turning back on itself without being absorbed? Once light has been absorbed, does it simply dissipate the excess energy through the material as heat, fluoresce it back as visible light (and in what direction?), or even do more "forbidden" transitions such as phosphorescence? The answer to all of these questions is "yes, but in varying degrees specific to the material." It even depends on the physical size and amount of material that you have present! So your worries about the rate at which light is able to pass through different materials really just becomes a question of how likely it is for the light to become "sidetracked" as it passes through the material. The net result is an apparent change in how fast the light passes through.
So finally, we can connect all of these nuanced ideas which could each fill a book of discussion on their own (and have) to the macroscopic perspective. All of these properties, for a material like a bulky glass window pane, can be summarized with three simple parameters such as the coefficients of absorption, transmittance, and reflectance of the material. Obviously, for light moving through normal glass, there is an overwhelming victory of the transmittance effects over the absorption and reflectance effects. Of course, you have also clearly experienced that standing at an alternate angle changes the propensity of reflectance of different kinds of light, mostly because you have changed the relative orientation of the light with respect to the overarching structure of the glass itself. This is explained much more deeply within the field of chemical crystallography.
The following is multiple choice question (with options) to answer.
What kind of surface would cause diffusion when light is reflected off of it? | [
"smooth surfaces",
"rough surfaces",
"hot surfaces",
"cold surfaces"
] | B | The angle of reflection equals the angle of incidence. A mirror has a smooth surface and reflects light at specific angles. Light is diffused when it reflects from a rough surface. Mirror images can be photographed and videotaped by instruments. |
SciQ | SciQ-7217 | species-identification, botany, ecology, trees
Title: Identifying a shrub with unusual "many shoots" growth behavior While recently hiking in the southern mountains of New Hampshire, we came across a plant, and some of them were exhibiting what we interpreted to be a disease, or least unusual growth. On some of the nodes, there were a large number of extra stalks:
On each plant, the number and locations of these things varied, and not all of them had it. And we first assumed it was some ivy, or parasite, or separate plant, but it seemed pretty clear to us that it was coming right from the same branch.
We soon saw there were dead versions of this plant, and all of them had this "extra shoot" variation:
So we reasoned that no matter what this thing was -- natural variation or some kind of disease -- it was killing the plants.
Google image search was no help. It possibly identified the plant as a "viburnum", but was unable to help with the growth.
Anyone know what plant this is, or what this growth behavior is the result of? Possibly an example of a "Witch's Broom."
Witch's Broom is a deformity in plants (typically woody species) which typically causes dense patches of stems/shoots to grow from a single point on the plant. The name comes from the broom-like appearance of the stems.1
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas, or viruses.2
Sources:
1. Wikipedia
2. Book of the British Countryside. Pub. London : Drive Publications, (1973). p. 519
Image1. Gardeningknowhow.com
Image2. Iowa state University
The following is multiple choice question (with options) to answer.
What are plants called that grow where you don't want them? | [
"weeds",
"shrubs",
"reeds",
"grasses"
] | A | We obviously can’t live without plants, but sometimes they cause us problems. Many plants are weeds. Weeds are plants that grow where people don’t want them, such as gardens and lawns. They take up space and use resources, hindering the growth of more desirable plants. People often introduce plants to new habitats where they lack natural predators and parasites. The introduced plants may spread rapidly and drive out native plants. Many plants produce pollen , which can cause allergies. Plants may also produce toxins that harm human health (see Figure below ). |
SciQ | SciQ-7218 | cosmology, universe, big-bang, theory-of-everything
This would lead to more complex things.
But now, what is a "thing" in this scenario?
Well, I don't know. Let's say "everything that one could give a name".
The first thing we got in this scenario was time, wich is quiet logical I think du it's necessary to seperate states from each other.
From now, everything is possible.
Now I claim that, depending on this scenario, everything that CAN raise, WILL raise.
I would be happy if one can proof me wrong on this argument.
This Theory has some big problems:
(1) Does the universe still fluctuate?
(1.1)If yes, why don't we notice that?
(1.1.1)Are the fluctuations too small?
(1.1.2)Why is conservation of energy true, if there could raise new energy?
(2)What about ultra-stable elements?
Well,... I'm ambivalent about that.
In one way this coud cause the universe to stop doing anything else due all potential would generate elements wich do not react to anything.
But looking at the periodic table of the elements, it seems as like exactly this is happening.
What I like at this theory:
(1) infinite scope:
If something can raise, it will. Well, it still can vanish at other time.
(2) no limit to speed of light:
The limit is what exist. But new things can exist later and even if it the speed of
light might be a limit at a time, it might not be at another time.
(3) Evolutionary:
The following is multiple choice question (with options) to answer.
Who proposed that everything in the universe exerts a force of attraction on everything else? | [
"newton",
"bell",
"wilson",
"einstein"
] | A | Giant steps in science may occur if a scientist introduces a major new idea. For example, in 1666, Isaac Newton introduced the idea that gravity is universal. People had long known that things fall to the ground because they are attracted by Earth. But Newton proposed that everything in the universe exerts a force of attraction on everything else. This idea is known as Newton’s law of universal gravitation. |
SciQ | SciQ-7219 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
Living organisms are comprised of organic compounds, which are molecules built around what element? | [
"helium",
"oxygen",
"silicon",
"carbon"
] | D | Living organisms are comprised of organic compounds, molecules built around the element carbon. |
SciQ | SciQ-7220 | everyday-chemistry, cleaning, minerals
Once you've got the crystal to the cleanliness you're happy with, you can polish it with powdered polish and a cloth, given time.
If instead of nice, angular crystals you're just trying to produce something like a smooth, rounded stone, after cleaning with water you can use a series of sandpapers (start at 60-80 grit and work up to ~400 grit) and polish to gradually smooth, then polish the stone by hand. This will clear away any deposits, but it will also change the surface of the stone itself. That might be acceptable to you if you've got something like a quartz river rock, and it will make a very nice end product. Take care to keep the stone wet while working, you don't want to breathe in rock dust if you don't have to.
The following is multiple choice question (with options) to answer.
Which mineral do native americans use to decorate items? | [
"Amethyst",
"Tanzanite",
"turquoise",
"Topaz"
] | C | Some minerals are valuable simply because they are beautiful. Jade has been used for thousands of years in China. Native Americans have been decorating items with turquoise since ancient times. Minerals like jade, turquoise, diamonds, and emeralds are gemstones. A gemstone is a material that is cut and polished to use in jewelry. Many gemstones, such as those shown in Figure below , are minerals. |
SciQ | SciQ-7221 | biochemistry
Alright so this is the oxidation of one mole of glucose equation (Without the ATPs) but till now I don't exactly know the correct answer for this question, but to not create any confusion this question is related to the Aerobic respiration (Glycolysis, Krebs Cycle and Electron transport chain).
Here's how I approached this question:
(a) is obviously not correct because the products of glycloysis are 2 pyruvate molecules and 2 ATP molecules so I checked off this choice.
(b) However seems correct because the products of 2 Krebs cycle is 4 CO2 and there is already 2CO2 when the pyruvate acid formed the 2 acetyl CoA molecules so in total that's 6CO2, but still what about the 6 Water molecules?
(c) is a very debating choice because when there is a "Complete occurrence of oxidative phosphorylation process" so that means 2 Krebs cycles had already occurred and formed the 6CO2, and during the oxidative phosphorylation process Water molecules are formed. and ATPs too? I don't exactly know about the ATPs, but aren't they supposed to be in the equation's products in order for this choice to be correct?
(d) This choice indicates to Krebs cycle but the water molecules only are formed during oxidative phosphorylation only.
So basically all the choices seems very debating and confusing and if I were to choose then I'll go with (C) because it's the only choice that makes sense for the water molecules (and the question asks for water), but I want someone to please answer this question with a brief explanation to why he chose this answer,
Thanks :) This reaction only means complete oxidation of glucose to 6 molecules of carbon dioxide and 6 molecules of water.
Reaction presented in question is very generalized, but the presence of six water molecules only means complete cellular respiration. Check out the actual biochemical pathways which take place to oxidize one glucose molecule.
And other options do not represent the complete cellular respiration, so there will not be formation of six water molecules, only option C means complete oxidation of glucose.
The following is multiple choice question (with options) to answer.
Glycolysis oxidizes glucose to two molecules of pyruvate? | [
"N/A - see below",
"glucose",
"N/A - see below",
"N/A - see below"
] | B | |
SciQ | SciQ-7222 | neuroscience, pathology, human-genetics, neurology
Presumably, genes in the first category contribute most to the shared phenotype of Down syndrome, and genes in the second category contribute most to the variation. Perhaps alleles that produce mRNA transcripts at the low end of normal for those genes are less susceptible to the effects of chromosome duplication.
A case study: Amyloid precursor protein
One protein of interest in particular is the amyloid precursor protein, APP, which is also associated with Alzheimer's disease (which shares some phenotypic characteristics with Down syndrome). APP expression varies widely among tissue types and individuals. Therefore, although APP mRNA levels are significantly elevated in Down syndrome individuals, the distributions between controls and Down syndrome are very overlapping; for example, see Figure 2B from the Antonarakis 2016 review.
3. Interactions with genes on other chromosomes
The third contributor to the variation of symptoms is the interaction of duplicated chromosome 21 genes with alleles located on other chromosomes. Just for an example where some of the genetic basis is understood, Down syndrome individuals are susceptible to certain leukemias, which are also associated with specific alleles on other chromosomes (Antonarakis, 2016). It seems that trisomy 21 affects histone modification in the areas of those alleles (Lane et al., 2014) and promotes proliferation of B-cells. Therefore, Down syndrome interacts with those other oncogenes to produce a greater combined risk. Individual with Down syndrome but not possessing the other alleles are less susceptible to the increased risk of leukemia
Similar interactions are likely with other systems that are influenced by Down syndrome, though the full molecular basis of all of those interactions are not fully understood. The Down Syndrome Genomes Project aims to, among other things, discover these other alleles outside of chromosome 21 that contribute to Down syndrome symptoms, which may also help understanding of the contribution of those alleles to other disorders (Antonarakis, 2016).
The following is multiple choice question (with options) to answer.
What's the most common disorder from having an extra chromosome? | [
"down syndrome",
"Turner syndrome",
"Williams syndrome",
"cri-du-chat syndrome"
] | A | One common example of an extra-chromosome disorder is Down syndrome ( Figure below ). Children with Down syndrome are mentally disabled and also have physical deformities. Down syndrome occurs when a baby receives an extra chromosome 21 from one of his or her parents. Usually, a child will receive one chromosome 21 from the mother and one chromosome 21 from the father. In an individual with Down syndrome, however, there are three copies of chromosome 21 ( Figure below ). Therefore, Down syndrome is also known as Trisomy 21. These people have 47 total chromosomes. |
SciQ | SciQ-7223 | respiration
Here is what happens at the molecular level.
The $\rm CN^-$ ions diffuse into the mitochondria. They have high affinity to the ferrous ion of the mitochondrial enzyme cytochrome c oxidase involved in the electron transport chain (ETC), one of the phases of cellular respiration where $\rm ATP$ is generated from $\rm NADH$ and $\rm FADH_2$. And it is this process that actually requires oxygen. The inhibited cytochrome c oxidase is of no good in transporting electrons, thus no $\rm ATP$ molecules are generated. The oxygen molecules waiting for those electrons remain empty handed resulting in the increase in the concentration of molecular oxygen. Remember, ETC occurs in almost all living cells except a few like RBC which get their major share of ATP from the highly inefficient anaerobic glycolysis. Also, $\rm ATP$ is the energy currency of our body and is required in a wide variety of bodily processes like osmotic balance, nerve impulse transmission, muscle contraction etc. With no $\rm ATP$ your heart and respiratory muscles can't contract, your medulla can't regulate breathing, your kidneys can't concentrate urine and the list goes on. Death is imminent if a high concentration of cyanide gets into your blood.
The symptoms of panic like tachypnea and tachycardia (that result due to low oxygen in blood) are not usually seen unless the victim himself knows he is poisoned. The end effects like cardiac and respiratory arrest, seizures and coma, however, are similar to those of suffocation.
For further read:
The Mechanism of Cyanide Intoxication and its Antagonism
The following is multiple choice question (with options) to answer.
What type of respiration does not use oxygen? | [
"oxidation",
"condensation",
"cellular",
"fermentation"
] | D | Fermented Foods. Fermentation is a type of respiration that doesn’t use oxygen. Fermentation by bacteria is used in brewing and baking. It is also used to make the foods pictured here. |
SciQ | SciQ-7224 | ocean, oceanography, atlantic
Title: What is that drain east of newfoundland On Google Maps I just found a drain east of Newfoundland:
More details at https://www.scribblemaps.com/maps/view/What_is_that/Jafix1
I wonder what that could be?
I heard about issues from different datasources which can occur when Google mixes data from NOAA or other sources with their own. Or could that be issued by a giant ice mountain drifting southwards? Or from the last ice age? It is an artifact of the processing software when it processes Multibeam Bathymetric Survey data.
You can get the lines of the different surveys from NGBC at NOAA (https://maps.ngdc.noaa.gov/viewers/bathymetry/). As you can see in the image below both lines you see in your example correspond to multibeam data. In the area there is a fair amount of single-beam bathymetry, but the multibeam bathy is often weighted differently creating artifacts in some cases.
The GEBCO bathymetry does not contain the artifact.
The following is multiple choice question (with options) to answer.
Besides depth soundings, what else are bathymetric maps made of? | [
"intensity data",
"sonar data",
"density measures",
"solar data"
] | B | Bathymetric maps are made from depth soundings or sonar data. They help oceanographers understand the shape of bottoms of lakes, bays, and the ocean. This information also helps boaters navigate safely. |
SciQ | SciQ-7225 | dna, chromosome
Title: Are human chromosomes connected or separate molecules? Do the 46 human chromosomes form a single unbroken DNA helix? Or is it rather that a human's genome consists of 46 disconnected helices?
If it is the former, does the common numbering scheme for the chromosomes have any correlation to their actual ordering in the one large strand?
If is the latter, is there a convention on how the chromosomes are ordered in genomic datasets? Also, is there a clear understanding of how sister chromosomes "find" each other in Meiosis I?
Generally, during periods when Mitosis/Meiosis are not occurring, what's a good physical picture for how the chromosomes are physically arranged (e.g. a bowl of 46 spaghetti noodles, or maybe the sister chromosomes always stay close together, etc)
thanks! Each chromosome is a pair of distinct, separate DNA molecules. A chromosome of an eukaryotic cell nucleus is a (long) helix of two linear molecules and so has two ends, which are called telomeres. DNA naturally forms a double helix with its complementary DNA molecule, and the double helix can further curl in what are called supercoils.
In humans, the chromosomes occur in 23 pairs (totaling 46). Except for the sex chromosome pair, each member of the pair is identical in appearance in a karyotype (picture) and each such pair has a number assigned from 1 to 22; the numbering generally follows the size of the chromosome, with chromosome 1 being the longest. In mammals, the sex chromosomes in a male are quite different in size and are labelled X and Y; a female has two identical X chromosomes.
The following is multiple choice question (with options) to answer.
A cell with two sets of chromosomes is called a? | [
"chloroplasts",
"diploid",
"biploid",
"haploid"
] | B | A cell with two sets of chromosomes is diploid , referred to as 2n , where n is the number of sets of chromosomes. Most of the cells in a human body are diploid. A cell with one set of chromosomes, such as a gamete, is haploid , referred to as n . Sex cells are haploid. When a haploid sperm ( n ) and a haploid egg ( n ) combine, a diploid zygote will be formed ( 2n ). In short, when a diploid zygote is formed, half of the DNA comes from each parent. |
SciQ | SciQ-7226 | embryology
Title: Is endoderm visible in the germ layer? This picture is my drawing about germ layer - not embryonic folding as I wrote initially.
Where exactly is the endoderm here in the picture?
The known things
Ectoderm
Neural tube
Notochord
Endoderm - Where is this?
Somite
Somite leg
Intraembryonic coelom
Embryonic somatopleura
Embryonic splanchopleura (lateral mesoderm)
Endoderm
Mesoderm (intraembryonic) I think you're going for a view of tube formation, in which case, here's a good image:
Lateral plate mesoderm
Intermediate mesoderm
Somite mesoderm
Chorda
Endoderm
(Reference)
Again in your drawing I think you correctly have it labeled as 10, and don't really need to put it twice.
The following is multiple choice question (with options) to answer.
On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast) extend into the blastocyst cavity and form this? | [
"embryo sac",
"algae sac",
"neural sac",
"yolk sac"
] | D | On the ventral side of the embryonic disc, opposite the amnion, cells in the lower layer of the embryonic disk (the hypoblast) extend into the blastocyst cavity and form a yolk sac. The yolk sac supplies some nutrients absorbed from the trophoblast and also provides primitive blood circulation to the developing embryo for the second and third week of development. When the placenta takes over nourishing the embryo at approximately week 4, the yolk sac has been greatly reduced in size and its main function is to serve as the source of blood cells and germ cells (cells that will give rise to gametes). During week 3, a finger-like outpocketing of the yolk sac develops into the allantois, a primitive excretory duct of the embryo that will become part of the urinary bladder. Together, the stalks of the yolk sac and allantois establish the outer structure of the umbilical cord. The last of the extra-embryonic membranes is the chorion, which is the one membrane that surrounds all others. The development of the chorion will be discussed in more detail shortly, as it relates to the growth and development of the placenta. |
SciQ | SciQ-7227 | reproduction, sociality, fitness
Title: Which monkey species features two distinct male phenotypes? I remember coming across a popular science article years ago about a monkey species which featured two male genotypes: the first were good looking males who acquired social status (as alphas or betas) within the group and could thus achieve reproductive succes. The alternative (less frequent) phenotype achieved similar fitness by adopting an outgroup (omega) lurking rapist kind of reproductive strategy.
Does anybody know which species and whose observervations I could be referring to? I'm curious to find out if this was a valid observation and if any further research has been done on this phenomenon. Patas monkeys exhibit "sneak mating" where a male other than the resident male sires offspring. Resident males do sire more offspring than sneaker males, but both strategies do co-occur. I'm pretty sure there are other species that have a similar mating strategy as well.
The following is multiple choice question (with options) to answer.
Pairs of fish that do not practice broadcast what may exhibit courtship behavior? | [
"feeding",
"migration",
"spawning",
"inheritance"
] | C | Vinegar is primarily an aqueous solution of acetic acid. Commercial vinegar typically contains 5.0 g of acetic acid in 95.0 g of water. What is the concentration of commercial vinegar? If only 3.1% of the acetic acid −. |
SciQ | SciQ-7228 | solar-flare, solar-storm
Title: Is the dark side of the earth protected from the risks of solar flares? Many speculate about the possibility of another “Carrington event”. Without getting into unrealistic scenarios, I ask myself the following question: would electronic lines and the equipment connected to them be safe if a large CME occurred, say, between 2am and 3am?
It would seem logical that a region that is not exposed to the sun at the time of the CME would be safe, but on the other hand, auroras occur at night, suggesting that solar flares do not just impact the daytime side of the earth. Nope
Solar flares don't work like "A massive blob of hot gas hitting the bright side of the Earth"
It's more similar to "A stream of ionized plasma that 'hits' the Earth's magnetic field and gets entangled in it"
Although the solar flares face the daytime side of the Earth, they still cause a significant impact on the nighttime side as well. The solar flares do not actually "hit" the earth, but instead either get caught in the Van Allen belts, a zone of ionized plasma about 640-58,000 km in height, or in the geomagnetic field, where they get funneled into the polar atmosphere and form auroras.
The Van Allen belts seem to be the most dangerous effect of the solar flares, as they have the potential to damage satellites.
TLDR: No, the dark side of the earth is NOT protected from a solar flare.
The following is multiple choice question (with options) to answer.
The van allen radiation belts are two regions in which energetic charged particles are trapped in earth’s what? | [
"ionosphere",
"gravitational field",
"magnetic field",
"cloud cover"
] | C | Figure 22.24 The Van Allen radiation belts are two regions in which energetic charged particles are trapped in the Earth’s magnetic field. One belt lies about 300 km above the Earth’s surface, the other about 16,000 km. Charged particles in these belts migrate along magnetic field lines and are partially reflected away from the poles by the stronger fields there. The charged particles that enter the atmosphere are replenished by the Sun and sources in deep outer space. |
SciQ | SciQ-7229 | life, extremophiles
Title: How close to Earth's core can organisms live? We don't to know much about organisms living deep below the Earth's crust. Recently a team led by S. Giovanni discovered some microbes 300 m below the ocean floor. The microbes were found to be a completley new and exotic species and apparently they feed off hydrocarbons like methane and benzene. Scientists speculate that life may exist in our Solar System far below the surface of some planets or moons. This raises some questions:
What is the theoretical minimum distance from Earth's core where life can still exist. Please explain how you came up with this number. For example, there are temperature-imposed limits on many biochemical processes.
Is there the potential to discover some truly alien life forms in the Earth's mantle (by this I mean, life which is not carbon based, or life which gets its energy in ways we have not seen before, or non DNA-based life, or something along these lines)?
What is the greatest distance below the Earth's crust that life has been discovered? I believe it is the 300 m I cited above, but I am not 100% sure. There's a lot we don't know about life in deep caves, but we can bound the deepest living organism to at least 3.5 kilometers down, and probably not more than 30 kilometers down.
The worms recovered from deep mining boreholes are not particularly specifically adapted to live that far down: they have similar oxygen/temperature requirements as surface nematodes.
The Tau Tona mine is about 3.5 kilometers deep and about 60˚ C at the bottom. Hydrothermal vent life does just fine up to about 80˚C, and the crust gets warmer at "about" 25˚C per kilometer. It's entirely reasonable to expect life to about 5 kilometers down, but further than that is speculation.
Increasing pressure helps to stabilize biological molecules that would otherwise disintegrate at those temperatures, so it's not impossible there could be life even deeper. It may even be likely, given that the Tau Tona life breathes oxygen.
I am certain no life we might recognize as life exists in the upper mantle.
The following is multiple choice question (with options) to answer.
What is the lowest level of organism that can perform all activities required for life? | [
"nucleus",
"system",
"cell",
"atom"
] | C | |
SciQ | SciQ-7230 | 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 umbrella term describes small structures that exist within cells and perform specialized functions? | [
"organelles",
"atoms",
"organisms",
"macromolecules"
] | A | To see an animation of this DNA molecule, click here (http://openstaxcollege. org/l/rotating_DNA2) . Some cells contain aggregates of macromolecules surrounded by membranes; these are called organelles. Organelles are small structures that exist within cells and perform specialized functions. All living things are made of cells; the cell itself is the smallest fundamental unit of structure and function in living organisms. (This requirement is why viruses are not considered living: they are not made of cells. To make new viruses, they have to invade and hijack a living cell; only then can they obtain the materials they need to reproduce. ) Some organisms consist of a single cell and others are multicellular. Cells are classified as prokaryotic or eukaryotic. Prokaryotes are single-celled organisms that lack organelles surrounded by a membrane and do not have nuclei surrounded by nuclear membranes; in contrast, the cells of eukaryotes do have membrane-bound organelles and nuclei. In most multicellular organisms, cells combine to make tissues, which are groups of similar cells carrying out the same function. Organs are collections of tissues grouped together based on a common function. Organs are present not only in animals but also in plants. An organ system is a higher level of organization that consists of functionally related organs. For example vertebrate animals have many organ systems, such as the circulatory system that transports blood throughout the body and to and from the lungs; it includes organs such as the heart and blood vessels. Organisms are individual living entities. For example, each tree in a forest is an organism. Single-celled prokaryotes and single-celled eukaryotes are also considered organisms and are typically referred to as microorganisms. |
SciQ | SciQ-7231 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What is the continental margin made of? | [
"continental drift",
"boundary crust",
"pangea",
"continental crust"
] | D | continental margin : The transition from the land to the deep sea. The continental margin is made of continental crust. More than one-quarter of the ocean basin is continental margin. |
SciQ | SciQ-7232 | physical-chemistry, solubility
Title: At what point does decreasing solvent temperature cause a decrease in gas solubility? Example: At constant pressure, carbon dioxide becomes less soluble in water as temperature increases. We also know that carbon dioxide becomes more soluble in water as temperature decreases.
Does introduction of order and loss of kinetic energy of solvent molecules eventually lead to a decrease in a solvent's ability to accommodate gas molecules? It is hard for me to believe that ice cubes can hold gas more effectively than the same volume of a glass of water. Rules such as "solubility of A in B rises with lower temperature" are only meant to be used if there is no phase transition of the participating substances.
The following is multiple choice question (with options) to answer.
What happens to gas solubility as the temperature increases? | [
"stabilizes",
"increases",
"decreases",
"fluctuates rapidly"
] | C | Gas solubility decreases as the temperature increases. |
SciQ | SciQ-7233 | geology
Title: What is this? A sinkhole?
Lat., long.38.47491, 43.48882, in the vicinity of Van in Turkey
I saw this when hiking. I want to know what it is and what are the dangers it poses. Lots of people hike that area in spring and summer, villagers collect edible plants in the area and graze livestock there. This is most likely a small slump scar modified by later erosion. If you look at the feature from a different angle in Google Earth, you will see that it's not even circular. It's more of a teardrop-ey crescent Moon shape, with the concave part downslope from the convex part. The bottom edge and top edge used to match up before the slide.
The following is multiple choice question (with options) to answer.
What forms when a glacier scrapes a large hole in the ground? | [
"melting lake",
"drift lake",
"frozen lake",
"glacial lake"
] | D | The depression that allows water to collect to form a lake may come about in a variety of ways. The Great Lakes, for example, are glacial lakes. A glacial lake forms when a glacier scrapes a large hole in the ground. When the glacier melts, the water fills the hole and forms a lake. Over time, water enters the lake from the sources mentioned above as well. |
SciQ | SciQ-7234 | plant-physiology, life
Title: Why are Arabidopsis plant seeds being sent to the moon and not other seeds? The latest Chang'e-4 rover brings an entire ecosystem with it, including Arabidopsis plant seeds and silkworms.
My question is: why Arabidopsis? Is this question conclusive without having to ask Chinese sources, such as just by having an educated guess as regards to the plant's own qualities? Without speculating further about specific decision making processes, Arabidopsis is the standard model organism in plant biology, similar to the mouse for mammals, the fruit fly for insects, C. elegans for nematodes, etc.
It's the first plant to have its genome sequenced, it's commonly used in undergraduate laboratory experiments in part because it grows very fast, etc.
If you were going to choose a plant arbitrarily for a research project, it might as well be Arabidopsis, I'd say it would be the default against which other options would be considered.
The following is multiple choice question (with options) to answer.
What branch of science holds hope for developing crops with genes that help them withstand harsh conditions? | [
"biotechnology",
"physiology",
"physics",
"chemistry"
] | A | Biotechnology will allow the development of crops containing genes that will help them to withstand harsh conditions. For example, drought and salty soil are two significant factors affecting how well crops grow. But there are crops that can withstand these harsh conditions. Why? Probably because of that plant's genetics. So scientists are studying plants that can cope with these extreme conditions. They hope to identify and isolate the genes that control these beneficial traits. The genes could then be transferred into more desirable crops, with the hope of producing the same traits in those crops. |
SciQ | SciQ-7235 | genetics, dna, dna-sequencing, human-genetics
Title: Do eukaryote cells contain DNA that isn't part of a chromosome or located in the mitochondria? I specify eukaryote in the title, but I'm also interested if this question isn't applicable to eukaryote cells in general but is to humans. I was reading "RNA-seq: An assessment of technical reproducibility and comparison with gene expression arrays" (John Marioni 2008).
In the results it states
"By these criteria, 40% of reads mapped uniquely to a genomic location, and of these, 65% mapped to autosomal or sex chromosomes (the remainder mapped almost exclusively to mitochondrial DNA)."
I couldn't help but notice the "almost exclusively to mitochondrial DNA". Almost exclusively? Can DNA be found in places other than chromosones or mitochondria? Perhaps I'm interpreting the sentence wrong. Any pointers would be appreciated
Thanks In plants, chloroplasts and other plastids contain DNA, but I suppose you are more interested in humans. Quoting from wikipedia,
In many cells cytoplasmic DNA is also found, which is different from
nuclear DNA, both in methylation levels (cytoplasmic has less), and in
sequence. EccDNA or extrachromosomal circular DNA is present in all
eukaryotic cells, derived from genomic DNA and consists of repetitive
sequences of DNA found in both coding and non-coding regions of
chromosomes. EccDNA can vary in size from less than 2000 more than
20,000 base pairs. In animals, eccDNA molecules have been shown to
contain repetitive sequences that are seen in satellite DNA, 5S
ribosomal DNA and telomere DNA. The function of eccDNA has not been widely studied, but it has been proposed that the production of elements of eccDNA from genomic DNA sequences adds to the plasticity of the eukaryotic genome and can influence genome stability, cell aging and the evolution of chromosomes
The following is multiple choice question (with options) to answer.
In eukaryotic cells, where is the dna kept? | [
"cytoplasm",
"epidermis",
"mitochondria",
"nucleus"
] | D | In eukaryotic cells, the DNA is kept in the nucleus. The nucleus is surrounded by a double membrane called the nuclear envelope. Within the nucleus is the nucleolus. |
SciQ | SciQ-7236 | homework-and-exercises, general-relativity, metric-tensor, integration
$$
or the surface area of the sphere.
To clarify: the differential geometric concept of volume is to be taken as a measure of the "size" of the space, regardless of dimensionality. Only in a 3-dimensional manifold does it correspond to what we in everyday life think of as a volume.
The following is multiple choice question (with options) to answer.
What is a measure of the amount of space that a substance or an object occupies? | [
"volume",
"power",
"mass",
"density"
] | A | Volume is a measure of the amount of space that a substance or an object takes up. The basic SI unit for volume is the cubic meter (m 3 ), but smaller volumes may be measured in cm 3 , and liquids may be measured in liters (L) or milliliters (mL). How the volume of matter is measured depends on its state. |
SciQ | SciQ-7237 | phylogenetics
Title: Shannon's Entropy and DNA I have been working with Shannon's entropy (SE) and DNA lately, and referring to the formula and concept of SE, I just wondered whether one should in the case of DNA use each nucleotide as having a probability to show up as 0,25 or if it was better to use the probability based on the frequency in the genome (let's say the human genome).
In the case of the latter being the better, is it interesting to have those frequencies at the scale of the genome, the chromosome, the sub segment ?
I'm interested in calculating the entropy relative to a short window (the length of an Illumina read, about 125-150bases), using the proportion of each base on a given sequence length. The idea is "how much information is given" in this sequence, and by information I mean how much different bases do I have.
It might that I'm missing some basic mathematics knowledge here, don't hesitate to point it out so I can understand it better
cheers, I think that genome-wide probabilities (i.e. not 0.25 for each base) should be fine. For a given segment of DNA, the chance that the sequence doesn't appear anywhere else in the genome is fairly high.
There is lots of patchy non-randomness (e.g. at centromeres, STRs, and other tandem repeat regions), but there's not much point in modelling that because it's not random.
The following is multiple choice question (with options) to answer.
What nucleic acid stores the genetic information? | [
"molecule",
"Nucleus",
"Ribosomes",
"dna"
] | D | Nucleic acids are large polymers formed by linking nucleotides together and are found in every cell. Deoxyribonucleic acid (DNA) is the nucleic acid that stores genetic information. If all the DNA in a typical mammalian cell were stretched out end to end, it would extend more than 2 m. Ribonucleic acid (RNA) is the nucleic acid responsible for using the genetic information encoded in DNA to produce the thousands of proteins found in living organisms. |
SciQ | SciQ-7238 | microbiology, cancer, toxicology
Title: Molds associated with Aflatoxin? I've been reading how some molds may be carcinogenic. In particular, molds associated with the fungus metabolite, Aflatoxin.
Are the types of mold that produce this toxin, present in buildings/showers/domestic environments, or do they only grow on food-stuffs? Strictly speaking the common bread mould Rhizopus sp. does not produce aflatoxin.
The fungus Aspergillus flavus which belongs to the class Ascomycetes secretes aflatoxin. It attacks cereal grains , legumes, tree nuts. The fungi are green in colour and 'mould' like in appearance.
The fungus attacks the food stuffs and storage grains. So under favourable conditions it may grow in your store room if it finds food for its growth. Also Aspergillus can grow at temperatures as high as 48°C and even at low temperatures like 5-8°C.
Edit: On being asked for sources I include some which strongly support my claim
1. For suitable conditions of growth of the fungi visit https://en.m.wikipedia.org/wiki/Aspergillus_flavus and read under the Environment heading.
2. Visit https://bioweb.uwlax.edu/bio203/s2013/ernst_ale2/habitat.htm and read from " Aspergillus flavus is omnipresent " upto " Aspergillus may also grow on or inside walls in homes, especially if the house is damp or has been damaged by flooding. "
3.https://www.moldbacteria.com/mold-types.html this site provides a list of different fungi found in our homes. Here you can find Aspergillus flavus to grow in flower pot soil. Moreover other species of Aspergillus are found in kitchens and bathrooms.
The following is multiple choice question (with options) to answer.
Molds growing on foods are a common type of what organisms that play very important roles in almost every terrestrial ecosystem on earth? | [
"yeast",
"mildew",
"pollen",
"fungi"
] | D | Do you see the organisms growing on the bread in the Figure below ? They belong to the Kingdom Fungi . Molds growing on foods are some of the most common fungi in our everyday lives. These organisms may seem useless, gross, and costly. But fungi play very important roles in almost every terrestrial ecosystem on Earth. |
SciQ | SciQ-7239 | optics, maxwell-equations
On the other hand, however well you understand the scalar-wave dynamics, you still need to construct a full vector solution, and if you want a rough-and-ready most-common-case answer for how this gets done, though, it turns out to be the first one above, which you mentioned in the question: the constant-polarization solution
$$\mathbf E(\mathbf r) = \mathbf E_0 u(\mathbf r).$$
It is easy to see that this is a solution to the wave equation, but as you say,
The following is multiple choice question (with options) to answer.
What of a electromagnetic wave can be calculated using the wave equation due to their speed always being constant? | [
"oscillation",
"sound",
"resonance",
"frequency"
] | D | Green light has a higher frequency than microwaves. It is possible to calculate it, but since the speed of an electromagnetic wave is constant we know that waves with higher wavelengths must have a lower frequency based on the wave equation. |
SciQ | SciQ-7240 | general-relativity, space, matter
According to general relativity, the concept of space detached from any physical content does not exist. The physical reality of space is represented by a field whose components are continuous functions of four independent variables-the coordinates of space and time. It is just this particular kind of dependence that expresses the spatial character of physical reality. Since the theory of general relativity implies the representation of physical reality by a continuous field, the concept of particles or material points cannot play a fundamental part, nor can the concept of motion. The particle can only appear as a limited region in space in which the field strength or the energy density are particularly high. This quote is within the framework of General Relativity only. It accepts that there exist "particles" but the only materialization of their existence as particles appears in the change of the functional form of the four independent variables-the coordinates of space and time. In such a mathematical model of Nature continuity is built in.
Now the question is how well this theory/model agrees with experimental observation and astrophysical ones. In astrophysics it does very well, it has not been falsified. ( note a theoretical proposal cannot be proven true, it can be validated by observations and falsified if one observation disagrees with predictions). So if we consider matter as just clusters of galaxies, galaxies, stars, planets and even satellites one can give an A++ for the validity of the General Relativity predictions and continuity of space time functions is one of them.
This is not true when we enter the realm of atoms, molecules and elementary particles . At the micro level quantum mechanics reigns and all our experiments point out that they are discontinuous entities with mass and discrete energy levels and discrete interactions. Three more interactions in addition to the gravitational one, which last General Relativity models as space time formation. Thus the quote is falsified by experimental data at the microscopic level.
At the moment the three elementary interactions, strong, weak and electromagnetic are unified in a theory called the Standard Model . Just today we learned that the Nobel prize for physics was awarded to prof Higgs and Englert for predicting this completion of the Standard Model decades ago, with the discovery of the Higgs by CERN groups in 2012.
The following is multiple choice question (with options) to answer.
Because of the wave character of matter, the idea of well-defined orbits gives way to a model in which there is a cloud of what? | [
"mutation",
"chaos",
"probability",
"particles"
] | C | Because of the wave character of matter, the idea of well-defined orbits gives way to a model in which there is a cloud of probability, consistent with Heisenberg’s uncertainty principle. Figure 30.48 shows how this applies to the ground state of hydrogen. If you try to follow the electron in some well-defined orbit using a probe that has a small enough wavelength to get some details, you will instead knock the electron out of its orbit. Each measurement of the electron’s position will find it to be in a definite location somewhere near the nucleus. Repeated measurements reveal a cloud of probability like that in the figure, with each speck the location determined by a single measurement. There is not a well-defined, circular-orbit type of distribution. Nature again proves to be different on a small scale than on a macroscopic scale. |
SciQ | SciQ-7241 | cell-biology, mitochondria
Title: How is the number of mitochondria in a cell regulated? How does the cell regulate the number of mitochondria in a cell? What happens when there are too many or too few? The concept you refer is recognized as mitochondrial biogenesis and it is regulated by AMPK which senses the cellular energy demand. If you have few mitochondria in the cell, the electron transport chain works suboptminally generating less ATP. When the AMP/ATP ratio is high (low ATP) AMPK is activated, and turns on the catabolic pathways required to produce more ATP, included mitochondrial biogenesis.
The following is multiple choice question (with options) to answer.
Metabolism is controlled by regulation of what? | [
"nucleus activity",
"cell activity",
"sequence activity",
"enzyme activity"
] | D | 8.5 Regulation of enzyme activity helps control metabolism. |
SciQ | SciQ-7242 | electrochemistry, gas-laws, temperature, gas-phase-chemistry
PM2.5
Inefficient combustion can also produce particles as soot, and there are more expensive "dust sensors" or "PM2.5 sensors" which measure small particles (2.5 microns or larger) in the air. Soot is a hallmark of incomplete combustion (think of the smoke from a badly tuned engine) and a huge problem from incomplete or low-temperature combustion from a garbage fire.
None of these will be conclusive, you'll have to look at your data and look at when there is a fire, and learn how the signals correlate to the events.
Ultraviolet light
There are UV light based fire detectors as well, but you'd need direct line-of sight access to the flames. If the sensor is designed to be solar-blind by adding a filter that removes all wavelengths from the Sun that make it to the ground, then it might be helpful here. However, they are usually designed to work indoors where indoor lighting may have less UV than outdoor sunlight. This would take some more investigation.
read the data sheets carefully
Finally, read each sensor's data sheet carefully and note carefully the specific voltages that each sensor needs. The "Air quality" sensors need you to run for a certain amount of time (about a minute) at one voltage, then a different amount of time at another voltage because the surface chemistry is a bit more complex.
Sensors can also be found here:
The following is multiple choice question (with options) to answer.
A catalytic converter filters pollutants in exhaust created by burning what before releasing it into the air? | [
"carbon dioxide",
"fossil fuels",
"noble gas",
"fossil compounds"
] | B | Some of the pollutants from fossil fuels can be filtered out of exhaust before it is released into the air. Other pollutants can be changed to harmless compounds before they are released. Two widely used technologies are scrubbers and catalytic converters. |
SciQ | SciQ-7243 | electromagnetic-radiation, electricity, electric-current, radio-frequency
In Cartesian coordinates, this is:
$$\mathbf A(\mathbf x)\simeq \frac {\mu_0 J_0 }{4 \pi } \ \hat {\mathbf x} \ \frac{e^{-ikr}}{r} \int_{- \frac a2}^{ \frac a2}dx' \int_{- \frac b2}^{ \frac b2} dy' e^{i k (x' \sin\theta \cos\phi + y'\sin\theta\cos\phi)}=\frac {\mu_0 J_0 }{4 \pi} \ \hat {\mathbf x} \ \frac{e^{-ikr}}{r} \int_{- \frac a2}^{ \frac a2}e^{i k ( \sin\theta \cos\phi)x'}dx' \int_{- \frac b2}^{ \frac b2} e^{i k ( \sin\theta\cos\phi)y'}dy'$$
So the vector potential is :
$$\mathbf A(\mathbf x)\simeq\frac {\mu_0 J_0 A }{4 \pi } \ \hat {\mathbf x} \ \frac{e^{-ikr}}{r} \ \frac{ \sin\bigr(k \frac {a}{2}(\sin\theta\cos\phi)\bigr)}{k \frac {a}{2}(\sin\theta\cos\phi)} \frac{ \sin\bigr(k \frac {b}{2}(\sin\theta\sin\phi)\bigr)}{k \frac {b}{2}(\sin\theta\sin\phi)}$$
And the electric field:
The following is multiple choice question (with options) to answer.
What are the two components of the ecf? | [
"solids and if",
"proteins and if",
"plasma and if",
"polymer and if"
] | C | Composition of Body Fluids The compositions of the two components of the ECF—plasma and IF—are more similar to each other than either is to the ICF (Figure 26.5). Blood plasma has high concentrations of sodium, chloride, bicarbonate, and protein. The IF has high concentrations of sodium, chloride, and bicarbonate, but a relatively lower concentration of protein. In contrast, the ICF has elevated amounts of potassium, phosphate, magnesium, and protein. Overall, the ICF contains high concentrations of potassium and phosphate ( HPO 24 − ), whereas both plasma and the ECF contain high concentrations of sodium and chloride. |
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