source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-2944 | atmosphere, clouds, thermodynamics, air-currents
Title: Elevation of Atmosphere differ? Does the atmosphere depth (or how high the air molecules from the ground) of Earth or Mars differ gradually or can there be plumes of atmosphere that reaches into space? If I were able to travel a perfect circle around the equator would the atmosphere differ in elevation? The atmosphere, as a whole, is approximately in hydrostatic equilibrium. This means that the gravity of the earth holds the atmosphere to the earth, preventing its escape, though few molecules may escape every so often.
Mathematically, this can be described by $$\frac{dP}{dr}=-\rho g$$ where P is the pressure, $\rho$ is the density, and $g$ is gravity. Using the Ideal Gas Law $$P=\rho R T$$, where $T$ is temperature and $R$ is the gas constant for air. Assuming that the temperature in the height of a column of the atmosphere is averaged ($\bar{T}$) an equation for the average height of the atmosphere can be found $$P(r,\phi,\lambda)=P_0(\phi,\lambda)exp(-\frac{(r-r_0)g}{R\bar{T}(\phi,\lambda)})=P_0(\phi,\lambda)exp(-\frac{gz}{R\bar{T}(\phi,\lambda)})$$
where $r_0$ is the radius of the earth,$P_0$ is the surface pressure, $r=z+r_0$, where $z$ is the height above the earth's surface, $\phi$ is the latitude, and $\lambda$ is the longitude.
To Summarize:
As the average temperature of the atmosphere increases, the height of the atmosphere will generally increase. This means that the height of the atmosphere will generally be the lowest near the poles, but highest near the equator. There are certainly exceptions to this rule, but this generally works. If you were to go around the equator, it will likely not be a "perfect circle" since the average temperature would have to be exactly the same.
The following is multiple choice question (with options) to answer.
As altitude rises, what happens to the temperature in the thermosphere? | [
"oxygen decreases",
"temperature decreases",
"oxygen increases",
"temperature increases"
] | D | Temperature increases with altitude in the thermosphere. Surprisingly, it may be higher than 1000° C (1800° F) near the top of this layer! The Sun’s energy there is very strong. The molecules absorb the Sun’s energy and are heated up. But there are so few gas molecules that the air still feels very cold. Molecules in the thermosphere gain or lose electrons. They then become charged particles called ions. |
SciQ | SciQ-2945 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
How many stomach compartments do ruminants have? | [
"four",
"seven",
"five",
"two"
] | A | To help digest the large amount of plant material, the stomach of the ruminants is a multi-chambered organ, as illustrated in Figure 34.8. The four compartments of the stomach are called the rumen, reticulum, omasum, and abomasum. These chambers contain many microbes that break down cellulose and ferment ingested food. The abomasum is the “true” stomach and is the equivalent of the monogastric stomach chamber where gastric juices are secreted. The four-compartment gastric chamber provides larger space and the microbial support necessary to digest plant material in ruminants. The fermentation process produces large amounts of gas in the stomach chamber, which must be eliminated. As in other animals, the small intestine plays an important role in nutrient absorption, and the large intestine helps in the elimination of waste. |
SciQ | SciQ-2946 | geophysics, seismology, core
Title: Why does seismic activity shed light on the inner core rigidity? Reading Introduction to Geology (MIT 2005) and Wikipedia's article on Earth's inner core, it is specified that:
Earth was discovered to have a solid inner core distinct from its liquid outer
core in 1936, by the seismologist Inge Lehmann, who deduced its presence from observations of earthquake-generated seismic waves that reflect off the boundary of the inner core and can be detected by sensitive seismographs on the Earth's surface.
Why does seismic activity would result in the conclusion that the inner core is rigid? What is the link between seismism and inner core? The question that Azzie Rogers linked to: How can we determine the size and composition of Earth's inner core?
Does answer the theory part of the question, but I will extrapolate a little more to answer the question.
The question becomes, what kind of waves travel through what? Both shear and compressional seismic waves can travel through solids, but as it turns out, you cannot shear a liquid. As you look at teleseismic raypaths (waves traveling far from the source) you can see that the wave must travel deep into the earth and then back up again. The wave forms, and directions of these wavepaths will be altered by the different compositions of Earth's layers as it travels through: a wave just traveling through the mantle will have both its shear and compressional component. A wave traveling through the mantle and outer core will lose its original shear component, and either develop a new one as it leaves the core (but distinct from the wave that travels through the mantle only) or not have one at all. And finally, a wave that travels through the mantle, outer core and inner core will have distinct wave patters as well. Its by this comparison of waveforms that we realize that the earth not only has different compositional layers, but phase boundaries as well. I am not sure seismology alone would lead to a solid inner core, but there is abundant evidence supporting that fact. When you combine Seismology, rare bits of geochemistry, the calculation of Earth's gravity , and perhaps the most important part, the magnetic dynamo generating our magnetic field, we see a fairly clear ( albeit incomplete) story.
The following is multiple choice question (with options) to answer.
Seismic waves show that the inner core of the earth is solid while the outer core is what? | [
"silicon",
"lava",
"liquid",
"gas"
] | C | The dense, iron core forms the center of the Earth. Scientists know that the core is metal from studying metallic meteorites and the Earth’s density. Seismic waves show that the outer core is liquid, while the inner core is solid. Movement within Earth's outer liquid iron core creates Earth’s magnetic field. These convection currents form in the outer core because the base of the outer core is heated by the even hotter inner core. |
SciQ | SciQ-2947 | electromagnetism, charge
You may ask why it is then so contrary to speak that two opposite charges cancel each other. No objection. All I want you to remember is that it is the net charge that is zero. Individually the charges are not zero. Take the example of an ionic crystal, say $NaCl$, where $Na^+$ and Cl^-$ ions are tightly held together by electrostatic attraction. Both ions have equal and opposite charges. If the interaction between the two lead to the individual destruction of charges (losing property as a charge), then how the solid continues to be so brittle. There is always interaction between the two ions. This means the interaction between the two charges do not cause the charges to lose their charge. It's the effective charge that is zero. We then speak about a system, not about individual charges.
The following is multiple choice question (with options) to answer.
What do ions of the same charge do? | [
"repel each other",
"discard each other",
"attract each other",
"merge"
] | A | Ions are highly reactive, especially as gases. They usually react with ions of opposite charge to form neutral compounds. For example, positive sodium ions and negative chloride ions react to form the neutral compound sodium chloride, commonly known as table salt. This occurs because oppositely charged ions attract each other. Ions with the same charge, on the other hand, repel each other. Ions are also deflected by a magnetic field, as you saw in the opening image of the northern lights. |
SciQ | SciQ-2948 | virology
Reference:
Jacques, D., McEwan, W., Hilditch, L. et al. HIV-1 uses dynamic capsid pores to import nucleotides and fuel encapsidated DNA synthesis. Nature 536, 349–353 (2016). doi.org/10.1038/nature19098
Zila, V., Müller, T. G., Müller, B., and Kräusslich, H.-G. (2021b). HIV-1 capsid is the key orchestrator of early viral replication. PLoS Pathog. 17:e1010109. doi: 10.1371/journal.ppat.1010109 At the time I couldn't find any info on this, but I recently came across a review covering the recent literature investigating this subject. To summarize, evidence currently supports entry of the intact capsid into the nucleus through the nuclear pore complex (NPC), (this is a surprising result!) reverse transcription occurring mostly in 'nuclear speckles', and capsid uncoating most likely occurs near the end of or shortly after cDNA transcript is complete.
The authors suggest the conical shape of the HIV capsid facilitates NPC entry, but there's no direct evidence for that yet.
Electron tomography and AFM studies directly observed partially broken capsids with nucleic acid exiting, both in cell nucleus and isolated capsids. This means there's likely no signal-mediated disassembly of the capsid and makes it more likely rupture is caused by internal stress.
Two observations that undercut the "cDNA > internal pressure > ruptured capsid" hypothesis are as follows:
However, the in silico model (130) also predicts that compaction of HIV-1 nucleic acids by the viral nucleocapsid (NC) protein, present within the core at high concentration, strongly alleviates outward forces acting on the capsid shell, and NC-mediated condensation of DNA into a tightly packed globule has been demonstrated in vitro (135). The limit of dsDNA length that can be accommodated within the HIV-1 capsid under authentic conditions is currently not known.
The following is multiple choice question (with options) to answer.
Integral proteins penetrate the hydrophobic interior of the what? | [
"lipid bilayer",
"skin bilayer",
"metabolism bilayer",
"carbon bilayer"
] | A | |
SciQ | SciQ-2949 | atmosphere, climate-change, thermodynamics, radiative-transfer
All of which have a compounding effect in the regional and to a lesser degree, global environment, that Chen et al. attribute to as being a cause of a 1-2K temperature rise in high altitude areas in Eurasia and North America and as a disrupting influence in global atmospheric circulation.
Edit 28/2/2016: There is an interesting blog post about a similar phenomenon: Dubai construction alters local climate
Additional references
Chen, B., and G.-Y. Shi, 2012: Estimation of the distribution
of global anthropogenic heat flux. Atmos. Oceanic
Sci. Lett., 5, 108–112.
The following is multiple choice question (with options) to answer.
The thermal properties of what substance largely contribute to the temperature climate of europe? | [
"lava",
"clouds",
"soil",
"water"
] | D | mass, water should be a gas at room temperature (20°C), but the strong intermolecular interactions in liquid water greatly increase its boiling point. Hydrogen bonding also produces the relatively open molecular arrangement found in ice, which causes ice to be less dense than water. Because ice floats on the surface of water, it creates an insulating layer that allows aquatic organisms to survive during cold winter months. These same strong intermolecular hydrogen-bonding interactions are also responsible for the high heat capacity of water and its high heat of fusion. A great deal of energy must be removed from water for it to freeze. Consequently, as noted in Chapter 5 "Energy Changes in Chemical Reactions", large bodies of water act as “thermal buffers” that have a stabilizing effect on the climate of adjacent land areas. Perhaps the most striking example of this effect is the fact that humans can live comfortably at very high latitudes. For example, palm trees grow in southern England at the same latitude (51°N) as the southern end of frigid Hudson Bay and northern Newfoundland in North America, areas known more for their moose populations than for their tropical vegetation. Warm water from the Gulf Stream current in the Atlantic Ocean flows clockwise from the tropical climate at the equator past the eastern coast of the United States and then turns toward England, where heat stored in the water is released. The temperate climate of Europe is largely attributable to the thermal properties of water. |
SciQ | SciQ-2950 | the-sun, solar-system, spectral-type, color
Title: Why the Sun is white if it is G2? I know it's a simple question, but even I progressed in astronomy, I always had this question. So, I know the Sun, in the MK classification system, it's G2: yellow. But I also know the sun, in visible spectrum, is white! But when I search for NASA photos of Sun in this spectrum, I find some photos with the Sun being yellow, and others white, with some of them being even orange! What is happening here? Is something incorrect? The sun is a star that emits energy in form of heat and light due to incandescence and nuclear fusion.
In this emission spectrum, we can see, there is a considerable amount of all visible colors being emitted so the light will appear as white to us from space.
But when observed from Earth due to Rayleigh scattering and the presence of these bluish colors being more than reddish ones the bluish colors are easily scattered giving the sky a blue color, now the light reaching us from the sun has more yellow-reddish colors, and that's why the sun seems yellow to us when observed from the ground. The colours of stars as per MK system is what the observer might observe without any optical aid, ie the light has been filtered in the atmosphere before reaching the observer.
The yellow sun in outer space is generally an edited image of the Sun.
This is the true color photo of the Sun.
The following is multiple choice question (with options) to answer.
Our sun is on the main sequence, like most stars, and it is classified by what colorful name? | [
"red dwarf",
"yellow dwarf",
"blue dwarf",
"white dwarf"
] | B | We have a main sequence star nearby. Our Sun is on the main sequence, classified as a yellow dwarf. Our Sun has been a main sequence star for about 5 billion years. As a medium-sized star, it will continue to shine for about 5 billion more years. Most stars are on the main sequence. |
SciQ | SciQ-2951 | thermodynamics, fluid-dynamics, temperature, flow
Title: How is melting time affected by flow rate and temperature of surroundings? Suppose you have a solid sphere of m, where m is an element with freezing point of 0 degrees Celsius.
In one scenario, you place your sphere in a (“static”) 25 degree Celsius environment and measure time, t, until melting. The sphere is fixed and cannot be displaced.
In the other, you place your sphere in environment with temperature, T, and with constant flow rate, v. Again, you measure time, t, until melting.
What is the equation that would relate the two scenarios? In other words, at what temperature and flow rate would time required for melting in the second scenario equal time required in the first? The answer to this is very subtle, and is the core subject of interest in convective heat transfer. In either case, you’ll find that most engineers would model either scenario using Newton’s law of cooling:
$$Q = hA(T-T_{\infty})$$
where $Q$ is the heat transfer rate, $A$ is the surface area of the object in contact with its surroundings, $T$ is the temperature of the object and $T_{\infty}$ is the (approximate) temperature of the surroundings. $h$ is a sort of catchall term called the “heat transfer coefficient”, which is affected by all sorts of things—in particular, by flow in the surroundings of the embedded object. Most engineers find this coefficient through empirical studies.
That being said, flow in general increases the amount of heat transfer, and so an object embedded in surroundings at a different temperature & a uniform flow will heat up/cool down to the surrounding temperature faster than without the flow.
In the case without flow, temperature gradients will actually cause flow themselves by changing the density of the fluid near the object with a different temperature, so there will still be some minor convective heat transfer—this is usually called natural convection.
The following is multiple choice question (with options) to answer.
Stirring, surface area, and temperature affect the rate at which what occurs? | [
"solute fragments",
"solute freezes",
"solute dissolves",
"concentration dissolves"
] | C | When you add sugar to a cold drink, you may stir it to help the sugar dissolve. If you don’t stir, the sugar may eventually dissolve, but it will take much longer. Stirring is one of several factors that affect how fast a solute dissolves in a solvent. Temperature is another factor. A solid solute dissolves faster at a higher temperature. For example, sugar dissolves faster in hot tea than in ice tea. A third factor that affects the rate of dissolving is the surface area of the solute. For example, if you put granulated sugar in a glass of ice tea, it will dissolve more quickly than the same amount of sugar in a cube. That’s because granulated sugar has much more surface area than a cube of sugar. You can see videos of all three factors at these URLs:. |
SciQ | SciQ-2952 | evolution, molecular-biology, molecular-evolution, abiogenesis
The issue isn't actually as clear-cut as it may seem, since there is a very wide unknown space between what we consider the most archaic forms of life, and any entity that could plausibly arise via purely abiotic processes; every theory of abiogenesis does assume that a lot of the features we consider essential to life must have arisen after some kind of replication appeared, meaning those features would have evolved. So there definitely is some evolutionary biology involved in investigating abiogenesis, and maybe if we ever solve abiogenesis it will be folded into the ToE (like I said, the ToE is actually a complex set of theories and observations, not one single thing. So while our understanding of what the theory says and can say currently excludes abiogenesis, our understanding and definition of the theory could evolve). But we haven't, and it currently isn't.
You need to edit your question however, because it is completely unclear from the title or text that you are asking about abiogenesis. Your question sounds like it's about embryonic development or biochemistry. Those are the current instances we have of organisms forming; whatever processes were at work in creating the very first life, well for one thing maybe we wouldn't want to call whatever that was an "organism", but more to the point those processes cannot happen today. The atmosphere is wrong and too full of oxygen, there are organisms everywhere vaccuuming up whatever resources those original biochemical processes might have used, basically there is likely no chemical environment on modern Earth that's anything like the chemical environment life originated in.
To answer your question though, abiogenesis is currently an unsolved question, so no, Science does not have an explanation of how the first organisms formed. But if you want to have an idea of how things could have happened, what the challenges are in figuring things out, and what things Science currently considers likely or impossible, there is a lot of active research in the field and many different hypotheses. The Wikipedia page for Abiogenesis has a fairly comprehensive rundown on this.
This video describes one of them (my favorite and the first I've found actually convincing, I have no expertise whatsoever to base this on but I plug it anyway; if nothing else it gives an appreciation for what kind of things the researchers in this field look at when thinking abiogenesis) :
The following is multiple choice question (with options) to answer.
What process of gradual change is the source of diversity of life on earth? | [
"development",
"variation",
"creation",
"evolution"
] | D | The Diversity of Life The fact that biology, as a science, has such a broad scope has to do with the tremendous diversity of life on earth. The source of this diversity is evolution, the process of gradual change during which new species arise from older species. Evolutionary biologists study the evolution of living things in everything from the microscopic world to ecosystems. The evolution of various life forms on Earth can be summarized in a phylogenetic tree (Figure 1.17). A phylogenetic tree is a diagram showing the evolutionary relationships among biological species based on similarities and differences in genetic or physical traits or both. A phylogenetic tree is composed of nodes and branches. The internal nodes represent ancestors and are points in evolution when, based on scientific evidence, an ancestor is thought to have diverged to form two new species. The length of each branch is proportional to the time elapsed since the split. |
SciQ | SciQ-2953 | adaptation
If you wish to try this for yourself, here is a description of the practice as quoted in the paper:
g Tum-mo yoga is a form of meditation which allegedly allows its practitioners to alter body temperature. Previously, only subjective descriptions of this phenomenon existed: "The neophytes sit on the ground, cross-legged and naked. Sheets are dipped in icy water, each man wraps himself in one of them and must dry it on his body. As soon as the sheet has become dry, it is again dipped in the water and placed on the novice's body to be dried as before. The operation goes on in that way until daybreak. Then he who has dried the largest number of sheets is declared the winner of the competition".
The following is multiple choice question (with options) to answer.
Shivering helps the body return to a stable what? | [
"weight",
"temperature",
"pH level",
"mood"
] | B | These people may be having fun in the icy water, but their bodies are struggling to react to the cold. For example, they may begin to shiver. Shivering helps the body return to a stable temperature. The body is always working to achieve stability, or homeostasis. |
SciQ | SciQ-2954 | aqueous-solution
A final point is that some dissolved species can, in fact, be solvents on their own. In this case, the definition of whether the species is aqueous or liquid is not well-defined and usually depends on the context. For example, a 1:4 mixture of $\ce{MeOH}$ and $\ce{H_2O}$ is typically written as $\ce{MeOH{(l)} + {H_2O{(l)}}}$, but a solution where a small amount of $\ce{MeOH}$ (maybe used as a reactant) would be denoted $\ce{MeOH{(aq)}}$. This has to do with the definition of the thermodynamic activities of the species and if you have questions about this, there's probably someone else on here who is a better expert than I to explain.
The following is multiple choice question (with options) to answer.
What term is used to describe a solution in which water is the solvent? | [
"aqueous solution",
"sediment solution",
"liquids solution",
"hydro solution"
] | A | Solutions We have previously defined solutions as homogeneous mixtures, meaning that the composition of the mixture (and therefore its properties) is uniform throughout its entire volume. Solutions occur frequently in nature and have also been implemented in many forms of manmade technology. We will explore a more thorough treatment of solution properties in the chapter on solutions and colloids, but here we will introduce some of the basic properties of solutions. The relative amount of a given solution component is known as its concentration. Often, though not always, a solution contains one component with a concentration that is significantly greater than that of all other components. This component is called the solvent and may be viewed as the medium in which the other components are dispersed, or dissolved. Solutions in which water is the solvent are, of course, very common on our planet. A solution in which water is the solvent is called an aqueous solution. A solute is a component of a solution that is typically present at a much lower concentration than the solvent. Solute concentrations are often described with qualitative terms such as dilute (of relatively low concentration) and concentrated (of relatively high concentration). Concentrations may be quantitatively assessed using a wide variety of measurement units, each convenient for particular applications. Molarity (M) is a useful concentration unit for many applications in chemistry. Molarity is defined as the number of moles of solute in exactly 1 liter (1 L) of the solution: M = mol solute L solution. |
SciQ | SciQ-2955 | image-processing, distance-metrics
If your images are not photographic images (or, are scientific images that are not ordinary subjects of photography), then please also post examples of their 2D autocorrelation, suitably cropped and scaled.
Face recognition is too big a topic to be discussed in a single question. Blurring arises in multiple context in face recognition - it can be a data quality issue, or it can be done intentionally as an intermediate step in data processing.
In face recognition we want to detect the identity of faces, therefore we have to ignore image differences that are not caused by identity differences. The basic category of differences that should be ignored in face recognition are: pose, illumination and facial expression.
A general approach to ignore irrelevant differences is called normalization, which attempts to apply various operations and transforms on the input image to obtain a "canonical" or "preprocessed" image, which in turn can be used for identification.
A second approach is to extract features from images that are highly-invariant from the irrelevant factors.
The quality of a face image is subject to the capturing device and the environment where it was captured. When a face image is captured without cooperation of the subject (such as from a security camera), poor image quality is an unavoidable consequence and had to be remedied by software so as not to hamper identification.
In cooperative capture, a computerized measure of image quality is good: the operator can be notified of quality problems and the image can be re-taken.
Blurring can also be an example of malicious tampering of biometrics in order to evade detection (along with occlusion and disguise). If the image is encoded digitally, a digital checksum and cryptographic signature is sufficient to solve the problem completely. If the blurred image is submitted in physical print by an impersonator, a computerized measure of facial image quality can be used to reject such submissions.
The lack of 2D-localizable features or interest points in a certain part of facial image can be a sign of intentional blurring.
However, the broad category of digital image tampering (by a skilled user of image-editing software), can only be dealt with Digital image forensics which compares pixel statistics against known camera models.
The following is multiple choice question (with options) to answer.
What is prosopagnosia? | [
"lack of memory",
"face blindness",
"way blindness",
"time blindness"
] | B | Brain: Prosopagnosia The failures of sensory perception can be unusual and debilitating. A particular sensory deficit that inhibits an important social function of humans is prosopagnosia, or face blindness. The word comes from the Greek words prosopa, that means “faces,” and agnosia, that means “not knowing. ” Some people may feel that they cannot recognize people easily by their faces. However, a person with prosopagnosia cannot recognize the most recognizable people in their respective cultures. They would not recognize the face of a celebrity, an important historical figure, or even a family member like their mother. They may not even recognize their own face. Prosopagnosia can be caused by trauma to the brain, or it can be present from birth. The exact cause of proposagnosia and the reason that it happens to some people is unclear. A study of the brains of people born with the deficit found that a specific region of the brain, the anterior fusiform gyrus of the temporal lobe, is often underdeveloped. This region of the brain is concerned with the recognition of visual stimuli and its possible association with memories. Though the evidence is not yet definitive, this region is likely to be where facial recognition occurs. Though this can be a devastating condition, people who suffer from it can get by—often by using other cues to recognize the people they see. Often, the sound of a person’s voice, or the presence of unique cues such as distinct facial features (a mole, for example) or hair color can help the sufferer recognize a familiar person. In the video on prosopagnosia provided in this section, a woman is shown having trouble recognizing celebrities, family members, and herself. In some situations, she can use other cues to help her recognize faces. |
SciQ | SciQ-2956 | cell-biology
Title: Are There Exceptions to Animal Cells not Having Cell Walls? In the January Issue of SciAm (discussing Haemophilia):
When damage occurs to blood vessels, exposure of the blood to collagen in the cell walls and material released by the cells triggers the activation of clotting factors.
I read the original in print, but it is available online here.
This seems to imply that animal cells (in this example, those of humans) have cell walls. I sometimes see similar implications in other resources. However, in elementary biology, one is taught that animal cells never have cell walls.
Therefore, my question: Are references to animal cell cell walls (such as the above, for human animal cells) simple mistakes--or are they exceptions to a generalization? Humans, as well as the rest of the metazoans (i.e. animals), absolutely do not have cell walls. What humans do have is extracellular matrix (ECM), which is the sort of fibrous, sort of gel-like material in which cells in many of the tissues are embedded. Collagen is a major component of ECM.
From the old copy of Alberts that is hosted on the NCBI website:
Tissues are not made up solely of cells. A substantial part of their volume is extracellular space, which is largely filled by an intricate network of macromolecules constituting the extracellular matrix (Figure 19-33). This matrix is composed of a variety of proteins and polysaccharides that are secreted locally and assembled into an organized meshwork in close association with the surface of the cell that produced them...
Two main classes of extracellular macromolecules make up the matrix: (1) polysaccharide chains of the class called glycosaminoglycans (GAGs), which are usually found covalently linked to protein in the form of proteoglycans, and (2) fibrous proteins, including collagen, elastin, fibronectin, and laminin, which have both structural and adhesive functions.
The following is multiple choice question (with options) to answer.
Fungi are unique in having cell walls made of what? | [
"prokaryotic",
"chitin",
"Protein",
"lectin"
] | B | Fungi are a kingdom in the domain Eukarya that includes molds, mushrooms, and yeasts. Most fungi are multicellular. They are unique in having cell walls made of chitin. |
SciQ | SciQ-2957 | universe
Title: What's the largest non-spherical astronomical object in the universe? Some asteroids and comets are non-spherical. But is the nature of big things and gravity so that large things in the universe are always spherical? What is the biggest astronomical object in terms of volume out there that's not spherical?
Note: Astronomical object is a defined term. See Astronomical object - Wikipedia. The largest sub-galactic astronomical object (in volume) that we know of is the Carina Nebula, which is a non-spherical diffuse nebula. The Carina Nebula has a radius of about 100 parsecs.
Image credit: ESA
If you consider astronomical objects of the galactic scale, then the galaxy IC 1101 is the largest astronomical object (in volume) that we know of. From Wikipedia:
The galaxy has a diameter of approximately 6 million light years, which makes it currently (as of 2013) the largest known galaxy in terms of breadth. It is the central galaxy of a massive cluster containing a mass (mostly dark matter) of roughly 100 trillion stars. Being more than 50 times the size of the Milky Way and 2000 times as massive
IC 1101 is on the left in the image below.
Here is an image from the Sloan Digital Sky Survey (SDSS) of IC 1101:
I'll leave it to you to decide if an elliptical galaxy counts as "spherical" or not.
If you don't count elliptical galaxies, the largest spiral galaxy is NGC 262, pictured below. It has a diameter of 1.3 million light years.
The following is multiple choice question (with options) to answer.
What is the largest body in the solar system? | [
"earth",
"asteroids",
"planet",
"sun"
] | D | Our Sun is a star. This star provides light and heat and supports almost all life on Earth. The Sun is the center of the solar system. It is by far the largest part of the solar system. Added together, all of the planets make up just 0.2 percent of the solar system's mass. The Sun makes up the remaining 99.8 percent of all the mass in the solar system ( Figure below )!. |
SciQ | SciQ-2958 | newtonian-mechanics, waves, earthquake
The group of curves inside the envelope but outside (2)
As the quake starts to show up, the pendulum notes down every fractional increase of the it's magnitude. And so, the inclination of the ellipses totally curve out (perpendicularly) thereby forming new ellipses at right angles to the previous ones. Now you might ask me a question...
Why are the perpendicular ellipses confined to a small region and do not spread out?
As you can see in the image, each and every fringe in the larger ellipses are equidistant (somewhat) from each other. As the magnitude increases, the fringes begin to compress which could be noticed in the small ellipses. This shows that the quakes weren't too smooth. As the pendulum starts the ellipse, the quake forces it to wiggle in the exactly opposite direction. For this reason,
The group of intertwined curves at the center
This is very very simple than the others. The earthquake has increased to its utmost magnitude. Now, the ground has shaken in every direction which has confused the pendulum to oscillate everywhere. Luckily, it has also made a rose by its random twist & twirl...
The following is multiple choice question (with options) to answer.
Which part of an earthquake is in the ground where the ground breaks? | [
"the tectonic plate",
"the focus",
"the fault",
"the epicenter"
] | B | The focus of an earthquake is in the ground where the ground breaks. The epicenter is the point at the surface just above the focus. |
SciQ | SciQ-2959 | everyday-chemistry, analytical-chemistry, identification
It fizzed and disappeared in vinegar.
It had a yellow-orange color in blue flame.
It's salty (note that it's usually a bad idea to taste random stuff you find on your floor).
The only white crystalline material that is a plausible candidate for being there and fizzes in acetic acid (ie vinegar) is calcite - $\ce{CaCO3}$. It's also a mineral that has 'retrograde solubility' meaning it dissolves more readily in cold water. This is probably how it got to the water in the first place. This is also why it precipitates on your electric kettle. It is the same stuff.
The salty stuff that burns yellow-orange is obviously $\ce{NaCl}$, aka table salt. It also probably dissolved with the vinegar as well. Why is the salty taste not quite like table salt? Well, first of all it is mixed with calcite. But, calcite has no taste. It's possible that there is some $\ce{KCl}$ or $\ce{MgCl2}$ in there as well. They are slightly more bitter than $\ce{NaCl}$. This is the stuff they use in low sodium salt.
There's another possibility - it could be any of the epsom salt family, $\ce{MgSO4.$n$\,H2O}$.
As to would this be dissolved in the first place, you can only speculate. You say that it came from a table that was outside. Did people eat there? Could people had spilled salt on it? Is the airborne dust in your area contain a lot of calcite? What about your basement? Could someone have spilled some salts on the floor, maybe even years ago?
The following is multiple choice question (with options) to answer.
What substances contained in lemons, vinegar, and sour candies have a sour taste? | [
"acids",
"proteins",
"lactose",
"fats"
] | A | Acids have a sour taste. Lemons, vinegar, and sour candies all contain acids. |
SciQ | SciQ-2960 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
Many microorganisms are single celled and use what for perception and movement? | [
"mitochondria",
"chloroplasts",
"nucleus",
"organelles"
] | D | Chapter 12 1 MRI uses the relative amount of water in tissue to distinguish different areas, so gray and white matter in the nervous system can be seen clearly in these images. 3 Neurons enable thought, perception, and movement. Plants do not move, so they do not need this type of tissue. Microorganisms are too small to have a nervous system. Many are single-celled, and therefore have organelles for perception and movement. 5 Sodium is moving into the cell because of the immense concentration gradient, whereas potassium is moving out because of the depolarization that sodium causes. However, they both move down their respective gradients, toward equilibrium. 7 A second signal from a separate presynaptic neuron can arrive slightly later, as long as it arrives before the first one dies off, or dissipates. 9 C 11 D 13 B 15 B 17 A 19 C 21 C 23 A 25 B 27 D 29 B 31 D 33 A 34 Running on a treadmill involves contraction of the skeletal muscles in the legs, increase in contraction of the cardiac muscle of the heart, and the production and secretion of sweat in the skin to stay cool. 36 The disease would target oligodendrocytes. In the CNS, oligodendrocytes provide the myelin for axons. 38 Afferent means “toward,” as in sensory information traveling from the periphery into the CNS. Efferent means “away from,” as in motor commands that travel from the brain down the spinal cord and out into the periphery. 40 The cell membrane must reach threshold before voltage-gated Na+ channels open. If threshold is not reached, those channels do not open, and the depolarizing phase of the action potential does not occur, the cell membrane will just go back to its resting state. 42 EPSP1 = +5 mV, EPSP2 = +7 mV, EPSP 3 = +10 mV, IPSP1 = -4 mV, IPSP2 = -3 mV. 5 + 7 + 10 – 4 – 3 = +15 mV. |
SciQ | SciQ-2961 | evolution, molecular-biology, molecular-evolution, abiogenesis
The issue isn't actually as clear-cut as it may seem, since there is a very wide unknown space between what we consider the most archaic forms of life, and any entity that could plausibly arise via purely abiotic processes; every theory of abiogenesis does assume that a lot of the features we consider essential to life must have arisen after some kind of replication appeared, meaning those features would have evolved. So there definitely is some evolutionary biology involved in investigating abiogenesis, and maybe if we ever solve abiogenesis it will be folded into the ToE (like I said, the ToE is actually a complex set of theories and observations, not one single thing. So while our understanding of what the theory says and can say currently excludes abiogenesis, our understanding and definition of the theory could evolve). But we haven't, and it currently isn't.
You need to edit your question however, because it is completely unclear from the title or text that you are asking about abiogenesis. Your question sounds like it's about embryonic development or biochemistry. Those are the current instances we have of organisms forming; whatever processes were at work in creating the very first life, well for one thing maybe we wouldn't want to call whatever that was an "organism", but more to the point those processes cannot happen today. The atmosphere is wrong and too full of oxygen, there are organisms everywhere vaccuuming up whatever resources those original biochemical processes might have used, basically there is likely no chemical environment on modern Earth that's anything like the chemical environment life originated in.
To answer your question though, abiogenesis is currently an unsolved question, so no, Science does not have an explanation of how the first organisms formed. But if you want to have an idea of how things could have happened, what the challenges are in figuring things out, and what things Science currently considers likely or impossible, there is a lot of active research in the field and many different hypotheses. The Wikipedia page for Abiogenesis has a fairly comprehensive rundown on this.
This video describes one of them (my favorite and the first I've found actually convincing, I have no expertise whatsoever to base this on but I plug it anyway; if nothing else it gives an appreciation for what kind of things the researchers in this field look at when thinking abiogenesis) :
The following is multiple choice question (with options) to answer.
Because it produces oxygen, what plant process was necessary for the evolution of animals? | [
"death",
"germination",
"photosynthesis",
"reproduction"
] | C | Eventually plants evolved. Plants produce oxygen as a product of photosynthesis. Oxygen spread around the planet about 2.5 billion years ago. Many organisms died off because they could not handle the oxygen. But this development was extremely important for other life. Animals need oxygen to breathe. If photosynthesis had not evolved there would be no animals. |
SciQ | SciQ-2962 | zoology, physiology, brain, ethology, behaviour
Robins, A., Lippolis, G., Bisazza, A., Vallortigara, G. & Rogers, L. J. (1998). Lateralized agonistic responses and hindlimb use in toads. Animal Behaviour, 56, 875–881.
Rogers, L. J. & Andrew, R. J. (Eds) (2002). Comparative Vertebrate Lateralization. Cambridge: Cambridge University Press.
Roth, E. D. (2003). ‘Handedness’ in snakes? Lateralization of coiling behaviour in a cottonmouth, Agkistrodon piscivorus leucostoma, population. Animal behaviour, 66(2), 337-341.
Shine, R., Olsson, M. M., LeMaster, M. P., Moore, I. T., & Mason, R. T. (2000). Are snakes right-handed? Asymmetry in hemipenis size and usage in gartersnakes (Thamnophis sirtalis). Behavioral Ecology, 11(4), 411-415.
Sovrano, V. A., Rainoldi, C., Bisazza, A. & Vallortigara, G. (1999). Roots of brain specializations: preferential left-eye use during mirror-image inspection in six species of teleost fish. Behavioural Brain Research, 106, 175–180.
Sovrano, V. A., Bisazza, A. & Vallortigara, G. (2001). Lateralization of response to social stimuli in fishes: a comparison between different methods and species. Physiology & Behavior, 74, 237– 244.
Vallortigara, G., Rogers, L. J., Bisazza, A., Lippolis, G. & Robins, A. (1998). Complementary right and left hemifield use for predatory and agonistic behaviour in toads. NeuroReport, 9, 3341–3344.
Vallortigara, G., Rogers, L. J. & Bisazza, A. (1999). Possible evolutionary origins of cognitive brain lateralization. Brain Research Reviews, 30, 164–175.
The following is multiple choice question (with options) to answer.
What category of animals in the vertebrate group has a relatively small brain but highly developed sense organs? | [
"fish",
"mammals",
"primates",
"arthropods"
] | A | Fish have a nervous system with a brain. Fish brains are small compared with the brains of other vertebrates. However, they are large and complex compared with the brains of invertebrates. Fish also have highly developed sense organs. They include organs to see, hear, feel, smell, and taste. |
SciQ | SciQ-2963 | evolution, human-evolution
Apes
The split between the line leading to modern humans and the line leading to modern chimpanzees occured somewhere around 4 to 7 million years ago. The clade is called Hominini. The split between those and the line leading to modern gorillas occured around 8 to 19 million years ago (yes, the dates are getting fuzzier). A fossil coming close to this ancestor may be Nakalipithecus nakayamai, however, we only have a fossil jaw from that species.
Going back, we get to the split between modern-day humans/chimpanzees/gorillas and modern-day orang-utans. This is the "ape" family, Hominidae. The largest ape that we know of, Gigantopithecus, that grew to about 3 meters, is classified as an orang-utan. Note that this is not a direct ancestor of humans. Even if our ancestors were larger than modern humans at this point it's unlikely that we are talking about anything larger than a big gorilla.
Primates
Going a bit in the reverse order here: The first true primates evolved around 55 million years ago. Fossils from that time are about the size of squirrels. Humans are "old world monkeys" who first appeared around 40 million years ago - the fossils from that clade we know, for example Apidium or Aegyptopithecus are a bit larger, some as large as a dog.
Primate-like mammals
The first primate-like mammals, called Plesiadapiformes appeared around 60 million years ago. We don't know all that much about them, but the most famous Purgatorius was the size of a rat or mouse.
Mammals / placenta mammals
Going back even further, things become even murkier, but early mammals were small. Placentalia, placental mammals appeared around 90 million years ago. They were small, arboreal (tree-dwelling) animals. Early mammals appeared around 160 million years ago and fossils we have from that time place them around the size of a shrew.
Now, is it possible that there were larger mammals in there somewhere, that then "shrunk" again? Sure. Just unlikely.
Therapsid
The following is multiple choice question (with options) to answer.
What distinguishing feature predates the branching of mammals from other vertebrates? | [
"teeth",
"adaptation",
"backbone",
"eggs"
] | C | |
SciQ | SciQ-2964 | acid-base, hydrogen, protons
Title: Is water hydronium and hydroxide? In our chemistry lesson when learning about the Bronsted-Lowry definition for acids and bases, we came across the reaction...
H2O + H2O -> H3O+ + OH-
...Where water is amphiprotic which means it acts as an acid and base. Does this mean that water is a combination of hydronium and hydroxide? How is it not harmful to drink then? If there are arrows going both ways then that means it’s in equilibrium between the right side (products) and the left side (reactants).
It doesn’t mean that water is a mix of H3O+ and -OH, a vast majority of water will stay H2O, and the small amount of H3O+ or -OH wouldn’t be anywhere near a concentration to hurt you
I think the purpose of that was to show that water has the potential to form H3O+ and -OH in itself in an attempt to teach you about acid base equilibrium
The following is multiple choice question (with options) to answer.
The simplest way to define a base is which kind of compound that produces hydroxide ions when dissolved in water? | [
"magnetic",
"covalent",
"ionic",
"solvent"
] | C | The simplest way to define a base is an ionic compound that produces hydroxide ions when dissolved in water. One of the most commonly used bases is sodium hydroxide, illustrated below. |
SciQ | SciQ-2965 | behaviour, language, genetic-code
Title: How does DNA encode high level features like animal behaviour and language? We know there are complex features which animals supposed to develop based on their genes as opposed to learning from the environment and the collective, also sometimes being very specific to certain species:
Concepts how to build homes
Animal languages including social insect interactions responsible for information transmission (or do they have to learn them through an acquisition process, let's exclude languages of ape tribes where "term" creation has been demonstrated?)
Valid answer: if already known, one or to examples to corresponding research.
Constraint: we are not talking about genes responsible for some sort of tendencies in behaviour but situations where there seems to be a more or less complex "blue print". I suppose we are yet very far from understanding these things. Relation of genotype to phenotype is teh subject of much contemporary research, but it is mainly limited to simple phenotypic features, explainable by action of a few genes, such as the colors of zebra fish mutants: see, e.g., this paper and the related publications by Nüsseln-Vollhardt group. Perhaps closer to your question is circadian rythms, which also have genetic determinants.
The complex behaviors are likely a result of the complex interactions of many genes, which are a very interesting, but also a very difficult problem to solve.
The following is multiple choice question (with options) to answer.
What is the term for behaviors that are closely controlled by genes with little or no environmental influence? | [
"learned behavior",
"observational behaviors",
"innate behaviors",
"reflex behaviors"
] | C | Behaviors that are closely controlled by genes with little or no environmental influence are called innate behaviors . These are behaviors that occur naturally in all members of a species whenever they are exposed to a certain stimulus. Innate behaviors do not have to be learned or practiced. They are also called instinctive behaviors. An instinct is the ability of an animal to perform a behavior the first time it is exposed to the proper stimulus. For example, a dog will drool the first time—and every time—it is exposed to food. |
SciQ | SciQ-2966 | inorganic-chemistry, redox, oxidation-state
Title: When HI reacts with H2SO4, why is the sulphate ion reduced to hydrogen sulphide instead of sulfur dioxide? When $\ce{HI}$ reacts with $\ce{H2SO4}$, it can be represented by the following chemical equation:
$$\ce{8HI + H2SO4 -> 4I2 + H2S + 4H2O}$$
However, when $\ce{HBr}$ reacts with $\ce{H2SO4}$, the sulphate ion is reduced to sulphur dioxide instead:
$$\ce{2HBr + H2SO4 -> Br2 + SO2 + 2H2O}$$
Could anyone account for the difference here? Is there any more cases where the sulphate ion is reduced to $\ce{H2S}$ instead of $\ce{SO2}$? The book intitled Qualitative Analysis emitted by F. P. Treadwell in $1924$ mentions in the chapter Iodine (p. 323) that the reaction depends on the relative amount of $\ce{H2SO4}$. In the presence of a great excess of $\ce{H2SO4}$, its reaction on $\ce{HI}$ or iodides produces $\ce{SO2}$ apart from $\ce{I2}$. In the presence of an excess of iodides, the reaction produces $\ce{H2S}$ as mentioned by Jelly Qwerty.
The following is multiple choice question (with options) to answer.
In the forward reaction, hydrogen and iodine combine to form what? | [
"ionic hydrogen",
"hydrogen ionicide",
"hydrogen iodide",
"iodinic hydrogen"
] | C | In the forward reaction, hydrogen and iodine combine to form hydrogen iodide. In the reverse reaction, hydrogen iodide decomposes back into hydrogen and iodine. The two reactions can be combined into one equation by the use of a double arrow. |
SciQ | SciQ-2967 | equilibrium, catalysis
Figure 1 (source: Chemguide.co.uk) Your realisation is correct and something chemistry teachers try to hammer into their students’ heads time and time again (and yet, the point is still often lost):
Catalysts will never change the thermodynamics of a reaction. They only ease the path of the reaction. Forward and backward reactions will be accelerated equivalently.
So what is the benefit of a catalyst? There are multiple ones.
Speed
Take for example the Haber-Bosch process to synthesise ammonia from nitrogen and hydrogen.
$$\ce{N2 + 3 H2 <=> 2 NH3}\tag{1}$$
$$\Delta_\mathrm{r} H^0_\mathrm{298~K} = -45.8~\mathrm{\frac{kJ}{mol}}$$
This reaction is exothermic and thus should, theoretically or thermodynamicly, proceed spontaneously, e.g. if you mixed nitrogen and hydrogen in the appropriate ratio and added a spark. It does not, however. Significant activation energy is required to cleave the $\ce{N#N}$ triple bond.
Typical methods to add activation energy include heating. In the Haber-Bosch process, the mixture is heated to $400$ to $500~\mathrm{^\circ C}$ to supply the required activation energy. However, since the reaction is exothermic, heating will favour the reactant side. Increasing the pressure improves the entropic term of the Gibbs free energy equation, hence why pressures of $15$ to $25~\mathrm{MPa}$ are used.
Catalysts, based on iron with different promotors, are used to accelerate the reaction. By using catalysts, one can lower the temperature required in a trade-off between speed of reaction and favouring the product side of the equilibrium. With the conditions and catalysts used, one achieves a yield of $\approx 15~\%$ of ammonia within a reasonable timeframe. Not employing a catalyst would give much lower yields at much longer timeframes — economically much less feasible.
Direct reaction path not accessable
The following is multiple choice question (with options) to answer.
Catalysts can greatly increase the rates of chemical what? | [
"reactions",
"decay",
"effects",
"photosynthesis"
] | A | and procaine. Not only do catalysts greatly increase the rates of reactions, but in some cases such as in petroleum refining, they also control which products are formed. The acceleration of a reaction by a catalyst is called catalysis. |
SciQ | SciQ-2968 | 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.
Ecology, botany, and zoology are what type of science? | [
"physical sciences",
"life science",
"chemistry",
"psychological sciences"
] | B | Life is complex and living things are incredibly diverse. Therefore, life science is divided into many fields, such as ecology, botany, and zoology. |
SciQ | SciQ-2969 | physical-chemistry, thermodynamics, equilibrium
Title: How can we define a non-spontaneous reaction? Consider a reaction:$$\ce{$aA + bB$ <=> $cC + dD$}$$
The value of reaction quotient at a certain time $t$, $${Q_c = \frac{[C]^c[D]^d}{[A]^a[B]^b}}$$
where the concentrations $[A], [B], [C]$ and $[D]$ are at time $t$.
Let the reaction start initially at $t = 0$, with only reactants $i.e.$ $[A]$ and $[B]$ equal to say $1$ mol and $[C]$ and $[D]$ equal to $0$ mol. Hence, $$Q_c = 0$$
We know that the value of equilibrium constant $K_c$ must be such that, $$K_c > 0$$
Thus, $$Q_c < K_c$$
Which is the only condition for the advancement of reaction in forward direction. This condition does not consider the value of change in Gibbs energy $\Delta G$.
Now, considering the relation $$\Delta G = \Delta G^o + RT~\mathrm{ln}~Q_c$$
When $Q_c = 0+$ then $\mathrm{ln}~Q_c \to -\infty$, which means $\Delta G << 0$ and reaction is spontaneous in forward direction.
Hence, can it be concluded that every reaction is spontaneous in forward direction if it starts with only reactants?
If so, how can we define a non-spontaneous reaction? It sounds like your confusion arises from not making a distinction between $\Delta G$ and $\Delta G^\circ$ when describing a reaction as spontaneous or not.
The $\Delta G^\circ$ is the free energy change for the reaction at the defined "standard" conditions of 1 M solute concentrations and/or 1 bar gas partial pressures of both the reactants and products. When we make the general statement that a reaction is spontaneous or not, we are usually referring to whether this $\Delta G^\circ$ is greater or less than 0.
The following is multiple choice question (with options) to answer.
How do we describe chemical reactions? | [
"atomic numbers",
"equilibrium",
"chemical equations",
"balanced reactions"
] | C | Chemical reactions are described using chemical equations. |
SciQ | SciQ-2970 | newtonian-mechanics, forces, mass, acceleration
And is "the body accelerating" thus by (4) ?
(4) $= {N \textbf{F} \over M}$ is the reason for the title "Force on body = multiple ?"
Considering objects on earth are known to be made of "few" "things" occupying volume (but not assuming the number of kind of particle in (3) is 1) $N$ might be the same value for every object. Thus "is earths gravity determined too big by a factor of billions?". Alright, so the situation here as you have presented focuses on how the earth pulls upon one particle whose mass is the total mass divided by number of particles represented as M/N, and the force as F. And then you said because the acceleration is the same for the small particle, it should also apply for the object at large because the object is not expanding or shrinking in anyway. And so far, the reasoning is on the right track but has some issues.
The issue with this is the force changing because you are dealing with an individual particle instead of the whole mass. The calculation you have shown says the gravitational force applied to the entire mass with its entire magnitude, also applies to each individual particle with its entire magnitude. This is where the issue comes from because the force actually decreases because equation for gravity is net F=Fg=mg. So actually for the equation you derived, Fg would be M/N times g because that is the force on each individual particle. Then if you solve for acceleration, you get M/N times g divided by M/N for mass and you a=g which is as you would expect if the object was in free fall.
So all in all we just derived above that the individual accelerations are actually g down so now we can extrapolate that since individual accelerations are g down, it means the entire acceleration of the object is g down because the object isn't changing shape or size.
So no, Earth's gravity is not too big; it perfectly matches the correct gravitational acceleration
The following is multiple choice question (with options) to answer.
Represented in equations by the letter "g", what pulls objects down to the earth's surface? | [
"light",
"motion",
"gravity",
"energy"
] | C | Gravity near the Earth pulls an object downwards toward the surface of the Earth with an acceleration of . In the absence of air resistance, all objects will fall with the same acceleration. The letter is used as the symbol for the acceleration of gravity. When talking about an object's acceleration, whether it is due to gravity or not, the acceleration of gravity is sometimes used as a unit of measurement where . So an object accelerating at 2g's is accelerating at or. |
SciQ | SciQ-2971 | evolution
Title: Is there any genetic similarity that defy evolution theory? For example,
say species A is common ancestor of B, and C. Species B is a common ancestor of D and E.
We would expect that there will be more genetic similarity between D and E than D and C. And those genetic similarity must exist in B.
In other word, we won't expect genetic similarity that don't "cross" the common ancestor or the evolutionary tree.
The exception is probably genetically engineered bacteria.
That being said, am I correct?
Some people say that we have similarity with pigs and chimps even though our common ancestors may be to far off. That won't happen right?
To summarize
I expect that evolutionary tree will form a well, tree. Genetic similarity would infect "nearby" trees and can't jump between trees without connectors, such as common ancestors.
Is that what we observe for ALL species? You have an excellent answer from Remi.b already but I just wanted to add/emphasise this (because there is always more than one way of explaining something and IMO the site benefits from having many answers to the questions)...
The tree we construct does not necessarily accurately reflect what happened in evolution. If B & C evolved from A, and D & E came from B, we would create this tree if we measured using the correct indicator. But the methods we have are not perfect. The first evolutionary trees were based on morphological descriptions etc. and clearly some of the classifications were going to be wrong. These days we use molecular methods, which are probably more accurate but could also be wrong some times. For example if we based our phylogeny on one SNP variant we could have some idea about the phylogeny between a few species, but if we based it on millions of SNPs we would have a much better idea - as technology & models improve that is becoming more realistic. The key point here being there is a difference between the trees we can draw from evidence, and the real evolutionary tree.
The following is multiple choice question (with options) to answer.
The similarity in biochemical compounds between living things provides evidence for the evolution of species from what? | [
"varied ancestors",
"rare tribes",
"common ancestors",
"recent ancestors"
] | C | Biochemical compounds are carbon-based compounds that are found in living things. The similarity in biochemical compounds between living things provides evidence for the evolution of species from common ancestors. |
SciQ | SciQ-2972 | zoology, species-identification, entomology
Title: Identification of a segmented black insect in France
Found in the Lot department of southern France. I think this is some sort of soldier fly larva (family Stratiomyidae). That would explain lack of legs. There are thousands of species world wide, with both aquatic and terrestrial larvae, so it might be possible to narrow it down a bit more.
Image from bugguide.net for comparison:
Thanks to @bli for reminding me of dipteran larvae!
The following is multiple choice question (with options) to answer.
The only invertebrates than can fly belong to what broad group, which is highly successful? | [
"bats",
"insects",
"spiders",
"birds"
] | B | Insects are the only invertebrates than can fly. Flight is the main reason for their success. |
SciQ | SciQ-2973 | dna, chromosome
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
But Why does DNA need to be coiled tightly into chromosomes?
DNA double helix is like a telephone wire. If length is to be measured, it will go beyond 60 miles. Some even say it can make a trip to the moon more than 150,000 times. Such a long DNA molecule is not only the part of each organism's cell nucleus but also it's invisible to the naked eye. This happens just because of the high packaging and coiling of this long DNA molecule.
Let's see the diagram to get an idea.
At the bottom of the diagram there is a sequence of nucleotides (ATGC) in different combinations. This can be considered as a gene if it codes for certain protein which is required for the growth or any other function of the body.
Returning back to your question, Complimentary base pairs are not genes.
Genes are the segments of DNA which is a long sequence of nucleotide base pairs that code for any protein or RNA transcript that contributes to any trait/phenotype/function of an individual.
With the tight packaging of DNA double helix along with help of packaging proteins(Histones and Non-histones), the chromatid and chromosomes are made. The packaging of DNA to chromosomes is highly controlled and is a whole different topic in itself.
The following is multiple choice question (with options) to answer.
The dna is wound around proteins called what? | [
"nucleotides",
"leptons",
"pepsins",
"histones"
] | D | Chapter 9 1 Figure 9.10 Ligase, as this enzyme joins together Okazaki fragments. 2 A 4 B 6 A 8 C 10 D 12 The DNA is wound around proteins called histones. The histones then stack together in a compact form that creates a fiber that is 30-nm thick. The fiber is further coiled for greater compactness. During metaphase of mitosis, the chromosome is at its most compact to facilitate chromosome movement. During interphase, there are denser areas of chromatin, called heterochromatin, that contain DNA that is not expressed, and less dense euchromatin that contains DNA that is expressed. 14 Telomerase has an inbuilt RNA template. |
SciQ | SciQ-2974 | evolution, mammals
Title: Why haven't land animals evolved beyond urination? It occurred to me (while urinating) that this would seem to be selected against because water is a scarce resource. Why are we constantly losing water we don't need to through urination? What is it about the chemistry of urine and the waste products eliminated that make urination necessary as opposed to eliminating them through defecation and recovering the water on the way out? It is probably true that toilets and other resting-ish area are always a great place to think about biology, I agree $\ddot \smile$.
Why do we urinate?
In short, urine contains the waste from our blood while defecation is just the stuff that we haven't digested. Kidneys are the organs responsible for draining wastes (mostly nitrogen-containing, or nitrogenous, wastes) from our blood.
Trade-off: energy cost vs. water loss
You're correct that the loss of water through urination is a considerable cost for an organism (especially those living in dry environments). But the amount of water used to excrete nitrogenous wastes is negatively correlated with the energy it costs to perform this excretion. In other words, there is a trade-off between water and energy loss during nitrogen excretion. Also, the question of toxicity is important.
Three ways to excrete nitrogenous wastes
Animals basically have three choices to excrete nitrogenous wastes:
Uric acid (excreted by uricotelic organisms)
Solid (crystal) with low water solubility
Low toxicity
Little water is needed
Lots of energy is needed
Ammonia (excreted by aminotelic organisms)
Highly soluble in water
High toxicity
Lots of water is needed to dilute it because of the toxicity
Not much energy is needed
Urea (excreted by ureotelic organisms)
Solid but highly soluble in water
"medium" amount of water is needed
"medium" toxicity
"medium" amount of energy is needed
The following is multiple choice question (with options) to answer.
What part of an animal helps to prevent water loss and gives support and protection? | [
"cuticle",
"exoskeleton",
"membrane",
"backbone"
] | B | The arthropod exoskeleton consists of several layers of cuticle. The exoskeleton prevents water loss and gives support and protection. It also acts as a counterforce for the contraction of muscles. The exoskeleton doesn’t grow as the animal grows. Therefore, it must be shed and replaced with a new one periodically through life. This is called molting . |
SciQ | SciQ-2975 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
Protozoa are generally difficult to identify due to what? | [
"their hidden shape",
"their formation shape",
"their resting shape",
"their varied shape"
] | D | 22.10 Protozoa As heterotrophs, protozoa scavenge materials from their surroundings. Others are predators which actively hunt or ambush small organisms such as bacteria and other protozoa for a source of nutrition. Protozoa can be parasitic as well; they may live inside larger organisms, like humans. Most protozoa live as single cells, although a few form colonies. Protozoa are generally difficult to identify due to their varied shape. They may appear as jelly-like blobs, spherical sunbursts, or a flattened leaf. Tiny blood parasites may be only 2 μm long. On the other hand, shell-covered marine may be 5 cm or more in diameter. Furthermore, different protozoans have their own complex life cycles. The complexity has led certain organisms to be mistakenly classified for other species. Nevertheless, protozoa can move, and so, they are classified based on their methods of locomotion. Characteristics of Protozoa : • About 30,000 species known • About 10,000 species are pathogenic, including some of the worst human diseases • heterotrophic • highly variable in form and life cycle. |
SciQ | SciQ-2976 | metabolism, nutrition, digestive-system
Title: Do I have to chew for digestion to kick in? Liquid nutrient-rich products (such as Soylent) are consumed without chewing. But if I have to chew to initiate digestion, are those nutrients really "processed"? If you had to chew to digest, then beverages like sugary sodas would never be digested or provide calories or nutrients, as you (generally) don't chew when you drink them. No, chewing is not required for digestion or nutrient absorption. Chewing is important when eating solid foods, as the chewing action breaks down and begins to solublize the food, and stimulates the production of saliva, which contains enzymes that begin to break down the food prior to digestion in the stomach and intestines.
The following is multiple choice question (with options) to answer.
Where does digestion begin? | [
"spicule cavity",
"gastrovascular cavity",
"oral cavity",
"excretory system"
] | B | |
SciQ | SciQ-2977 | organic-chemistry, reaction-mechanism, alcohols
The primary carbon will not, as stated above, form a primary carbocation since it is too unstable. Hence only the bimolecular substitution will occur. If no primary carbocation is generated, no Wagner-Meerwein rearrangement can occur. And the mechanism of an $\mathrm{S_N2}$ reaction does not allow bromide’s (or anything else’s) migration.
The secondary carbon could undergo bimolecular substitution, too. The reaction rate will probably be slower than that of fragmentation and rearrangement, though, since the latter are unimolecular processes. And other shifts (e.g. methyl followed by hydride) are possible but again slower since you need to shift twice. All in all, a higher proportion of side-products may be expected.
In no case will the bromide shift after substitution; any shift would need to occur before.
The following is multiple choice question (with options) to answer.
What basic units are neither created nor destroyed during a chemical change, but are instead rearranged? | [
"particles",
"Electrons",
"molecules",
"atoms"
] | D | Atoms are neither created nor destroyed during a chemical change, but are instead rearranged to yield. |
SciQ | SciQ-2978 | nitrogen
Step three is when plants and the animals that live of the plants die and breaks down into ammonia and other waste products (this is where many explanations of the nitrogen cycle usually starts). The waste products gets converted into ammonia by bacteria and the ammonia gets converted to nitrite and the entire cycle starts all over again.
Legumes have a symbiotic relationship with some bacteria that can fixate nitrogen (N2) https://aces.nmsu.edu/pubs/_a/A129/
sources:
https://science.howstuffworks.com/life/biology-fields/nitrogen-cycle.htm
https://www.britannica.com/science/denitrifying-bacteria
The rest is from my memory.
The following is multiple choice question (with options) to answer.
Which members of the food chain break down remains of plants and other organisms when they die? | [
"fluxes",
"decomposers",
"Respiration",
"nematodes"
] | B | When plants and other organisms die, decomposers break down their remains. In the process, they release nitrogen in the form of ammonium ions. Nitrifying bacteria change the ammonium ions into nitrates. Some of the nitrates are used by plants. Some are changed back to nitrogen gas by denitrifying bacteria. |
SciQ | SciQ-2979 | aqueous-solution, solubility, solvents, solutions
Title: Does removing solution affect a supersaturated solution Given a mixture of: a saturated solution of a solute in a solvent together with excess of the solute compound as crystalline material.
If one were to change the bulk composition of the mixture by removing some of the solution could this cause dissolution or precipitation of the solid in the remaining mixture, or the concentration of the remaining solution?
Presumably one should expect some crystallisation in the portion of the solution that is removed from the mixture?
If one were to change the bulk composition of the mixture by removing some of the solution [...]
This does not change the composition of the solution above the solid. Since the concentration of the solute remains constant, I do not expect a change.
Presumably one should expect some crystallisation in the portion of the solution that is removed from the mixture?
It still is a saturated solution. Unless you evaporate the solvent (= increase the concentration of the solute) or change the temperature, nothing will change.
The following is multiple choice question (with options) to answer.
Concentration is the removal of solvent, which increases the concentration of what? | [
"vapor",
"solute",
"sodium",
"Water"
] | B | Often, a worker will need to change the concentration of a solution by changing the amount of solvent. Dilution is the addition of solvent, which decreases the concentration of the solute in the solution. Concentration is the removal of solvent, which increases the concentration of the solute in the solution. (Do not confuse the two uses of the word concentration here!) In both dilution and concentration, the amount of solute stays the same. This gives us a way to calculate what the new solution volume must be for the desired concentration of solute. From the definition of molarity,. |
SciQ | SciQ-2980 | fracking, clathrates
Title: Do we know how large deposits of methane clathrates were formed in permafrost regions? We can see that there are large buildups of methane clathrates in permafrost regions. This seems different to the buildups of natural gas which fracking releases, which appear to have just come from escaped gases from oil/coal deposits.
My question is: Do we know how large deposits of methane clathrates were formed in permafrost regions? Rotting vegetation generates methane, or marsh gas as it is sometimes called. The most obvious method by which clathrates were formed in Arctic regions is that many years ago during summer and autumn, rotting vegetation produced methane, which combined with water at cold temperatures to produce methane ice, otherwise known as clathrates. Extremely cold temperatures are not necessary to form clathrates. They form at the bottom of deep seas, where the temperature even in the tropics is a constant 4 or 5 C. There are huge deposits of clathrates on the deep ocean floor, and there has been talk of exploiting them commercially.
A theory to explain the Permo-Triassic extinction event of 250 million years ago hypothesises that super-eruptions in the Siberian Traps super-volcano raised temperatures enough to release vast quantities of methane from tundras and ocean beds, so that with the additional greenhouse gas the average temperature rose by about 10 C, causing the extinction of nearly 90 percent of all large animals, a greater mass extinction than the better known event at the end of the Cretaceous.
The following is multiple choice question (with options) to answer.
What type of coal deposits are the most extensive ever formed? | [
"jurassic",
"precambrian",
"carboniferous",
"mesozoic"
] | C | |
SciQ | SciQ-2981 | species-identification, zoology, marine-biology, ichthyology, bone
Title: Identification of a strange skull My father is a fisherman in the Baltic sea, and he has found this very strange skull. I would like to know to which animal it belonged. Can someone help identify it? Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is indeed a neurocranium.(source of the picture).
Thank you all for your help!
The following is multiple choice question (with options) to answer.
What is the term for the skeletal structure of the head that supports the face and protects the brain? | [
"ribcage",
"cranium (skull)",
"pelvis",
"thorax"
] | B | 7.2 | The Skull By the end of this section, you will be able to: • List and identify the bones of the brain case and face • Locate the major suture lines of the skull and name the bones associated with each • Locate and define the boundaries of the anterior, middle, and posterior cranial fossae, the temporal fossa, and infratemporal fossa • Define the paranasal sinuses and identify the location of each • Name the bones that make up the walls of the orbit and identify the openings associated with the orbit • Identify the bones and structures that form the nasal septum and nasal conchae, and locate the hyoid bone • Identify the bony openings of the skull The cranium (skull) is the skeletal structure of the head that supports the face and protects the brain. It is subdivided into the facial bones and the brain case, or cranial vault (Figure 7.3). The facial bones underlie the facial structures, form the nasal cavity, enclose the eyeballs, and support the teeth of the upper and lower jaws. The rounded brain case surrounds and protects the brain and houses the middle and inner ear structures. In the adult, the skull consists of 22 individual bones, 21 of which are immobile and united into a single unit. The 22nd bone is the mandible (lower jaw), which is the only moveable bone of the skull. |
SciQ | SciQ-2982 | evolution, terminology, natural-selection, computational-model, definitions
On the other hand suppose we have some environment in which there are two anisofit fitness related hereditary material populations. Now if some environmental, or recombinative genetic change inflicts those two populations, that works either in a neutral manner, i.e. causes equal population sizes of those anisofit fitness related hereditary material, or works in an opposite-directional manner, i.e. in a direction that is opposite of the expected direction mentioned above, better be termed as "contra-directional". In this situation even if the size of the populations of those hereditary materials is different (imparting the appearance of a selection) still that difference is not explained by the effect of those anisofit fitness related hereditary material on their fitness in that environment! So this would not be an example of natural selection! It would be an example of an environmental factor that caused a "genetic drift", or of a genetic recombination process that caused a "genetic drift" also.
So we in effect have a struggle between "natural selection" which works in the direction of increasing adaptation with the environment, on one hand, and "random selection" (or sometimes called neutral selection or non-selection) which doesn't necessarily work in the direction of increasing adaptation with the environment.
So in some sense "evolution" is determined by the struggle of those two kinds of mechanism of change.
If random change prevails, then evolution would not necessarily move in the direction of increasing adaptation of living organisms with their environment. While if "natural selection" prevails, then evolution would proceed in the direction of increasing adaptation to the environment. I've mostly skimmed the formalism you introduced, but getting to the 2nd half of your post, the answer is yes, you understood correctly the distinction between natural selection (aka adaptive evolution) and drift (aka neutral evolution), as well as the fact that it's not a given that natural selection would be the predominant effect in arbitrary circumstances. Small population sizes, high rates of mutation, weak genetic repair mechanisms, etc. can all lead to chance being the predominant effect.
The conditions needed for natural selection to be predominant have been investigated in lots and lots of publications. A quick overview and brief list of such publications is found in
Duret, L. (2008) Neutral theory: The null hypothesis of molecular evolution. Nature Education
The following is multiple choice question (with options) to answer.
What is it called when organisms with traits that better enable them to adapt to their environment tend to survive and reproduce in greater numbers? | [
"natural selection",
"evolution",
"natural distribution",
"adaptation"
] | A | New species develop naturally through the process of natural selection . Due to natural selection, organisms with traits that better enable them to adapt to their environment will tend to survive and reproduce in greater numbers. Natural selection causes beneficial heritable traits to become more common in a population and unfavorable heritable traits to become less common. For example, a giraffe’s neck is beneficial because it allows the giraffe to reach leaves high in trees. Natural selection caused this beneficial trait to become more common than short necks. |
SciQ | SciQ-2983 | zoology, ornithology, ethology, behaviour
Title: Crow branch pecking behaviour I was walking through a small park when two crows started cawing at me, and followed me, flying from tree-to-tree as I walked. I speculate that this is a territorial or protective behaviour, but what I found different was the crows were violently pecking the branches nearby them. I have no memories coming to mind of seeing this behaviour beforehand. I speculate that this behaviour could be threat displays, but a quick search on Google did not reveal to me any authoritative studies on this phenomenon. I'd appreciate more information and sources.
This question has been added as a casual observation on iNaturalist. This is a good question. This type of behavior -- pecking at a branch, wiping the side of the beak on a branch, pulling off twigs and dropping them, or knocking off pieces of bark -- is quite common among many corvid species, particularly when they are interrupted by something or someone that they might consider a threat. This includes not only potential predators but also potentially hostile conspecifics.
It is typically considered to be a form of displacement behavior. The concept of displacement behavior, from classical ethology, posits that when an animal experiences two conflicting drives to do two different things, it doesn't know which to do and does a third thing instead to dissipate the drive or anxiety. For branch-pecking in crows, see E.g Kilham and Waltermire 1990 Ch. 12.
Referece: Kilham, L., & Waltermire, J. (1990). The American crow and the common raven. Texas A&M University Press.
The following is multiple choice question (with options) to answer.
A crow that becomes used to a scarecrow and lands on it is an example of what? | [
"adaptation",
"assimilation",
"habituation",
"dissociation"
] | C | Another example of habituation is shown below ( Figure below ). Crows and most other birds are usually afraid of people. They avoid coming close to people, or they fly away when people come near them. The crows landing on this scarecrow have become used to a “human” in this place. They have learned that the scarecrow poses no danger. They are no longer afraid to come close. They have become habituated to the scarecrow. |
SciQ | SciQ-2984 | physical-chemistry, reaction-mechanism, free-energy
How does it come, that in one case the activity of the whole product AB is important and in another the single activities of the components of the product?
Equation (1) refers to a molar free energy of formation of $\ce{AB}$ from reagents $A$ and $B$, all under the same constant (P,T, composition) conditions, whereas (2) refers to the free energy of formation of a solid solution of $n_A$ moles of A and $n_B$ moles of B from pure components. Equation (1) refers to combination of A and B at a 1:1 mole ratio, or equivalently reaction to form 1 mole of $\ce{AB}$ from $n_A=n_B=\pu{1 mol}$. Reaction (2) refers to mixture of A and B at any arbitrary ratio or total number of moles. Therefore equation (2) is in a way more general. Also, equation (1) refers to a differential process (transformation to form 1 mole of product under contant conditions) whereas (2) refers to an integral (mixing) process.
For the given reaction:
$$\Delta G = \Delta G^⦵ + RT\ln{\frac{a_\ce{AB}}{a_\ce{A}\cdot a_\ce{B}}} $$
Since all components are pure solid substances, all activities equal 1 and therefore, $\Delta G = \Delta G^⦵$.
The following is multiple choice question (with options) to answer.
What term is used to describe the sequence of elementary steps that together comprise an entire chemical reaction? | [
"elemental mechanism",
"source mechanism",
"potassium mechanism",
"reaction mechanism"
] | D | In this equation, the letters A and B represent the reactants that begin the reaction, and the letter C represents the product that is synthesized in the reaction. The arrow shows the direction in which the reaction occurs. |
SciQ | SciQ-2985 | 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.
Structurally, diplomonads have two equal-sized what and multiple flagella? | [
"neutrons",
"nuclei",
"electrons",
"atoms"
] | B | |
SciQ | SciQ-2986 | quantum-mechanics, wavefunction, electrons, hamiltonian
This may be confusing as we are including the wavefunction of the interested electron (the effect) in calculating what could be the possible cause "on" it to have that effect. This is the crux of the mean field approach where effect feedbacks the cause until we reach at a 'self-consistent' description of the cause-effect process! (self-consistent description is the physics lexicon used for this process.)
Some caveats : While integrating over all possible ${\bf r}^'$ we encounter a singularity when ${\bf r}^' = {\bf r}$. This is dealt with what is called "self-interaction" term and correction. I dont have good understanding of this.
The following is multiple choice question (with options) to answer.
What is the term for the affected factor in an experiment? | [
"multiple variable",
"stable variable",
"dependent variable",
"independent variable"
] | C | Test the hypothesis. Make predictions based on the hypothesis and then determine if they are correct. This may involve carrying out an experiment. An experiment is a controlled scientific test that often takes place in a lab. It investigates the effects of one factor, called the independent variable , on another factor, called the dependent variable . Experimental controls are other factors that might affect the dependent variable. Controls are kept constant so they will not affect the results of the experiment. |
SciQ | SciQ-2987 | proteins, protein-folding, protein-structure, xray-crystallography
Because most proteins have hydrophilic regions on the exterior surface of the structure, crystals of proteins actually contain a considerable fraction of water molecules within the crystal itself. These water molecules are part of the crystal because they are interacting with those hydrophilic residues on the tertiary surface of the protein, both by hydrogen bonding, in some cases, and less specific polar interactions in other cases. This is at least one of the reasons why obtaining a crystal of any random protein is not at all a routine endeavor. The large proportion of water in these crystals make them very fragile once they do form, as well as not necessarily likely to form in the first place.
If you go into the technical literature to look at the electron density maps that the more commonly diagrammed structure maps are derived from, you'll be able to actually trace water molecules surrounding the individual protein molecules.
In fact, in the days of development of protein crystallography, assigning correct specific atoms to the various electron density peaks was a decidedly non-trivial task.
Effectively, despite being a crystal, the microenvironment experienced by the protein within the crystal is very much like that in an aqueous environment. The hydrophobic interactions & hydrophilic interactions will not be very different from those in solution.
That is, the crystalline state achieved is not, in fact, "a complete change of surrounding environment" to use the phrase that you've used in your post.
The following is multiple choice question (with options) to answer.
Furthermore, most of the proteins within membranes have both hydrophobic and which other regions? | [
"hydrophilic",
"cytosolic",
"atmospheric",
"lymphatic"
] | A | |
SciQ | SciQ-2988 | biochemistry, synthesis, proteins, amino-acids
Also, assume a constant amount of amino acids always being added to the resin to couple. If only the so far correctly built sequences are available, these will ‘see’ a higher ‘concentration per site’ of their coupling partners maybe resulting in slightly increased yield, too. (Note that this paragraph used layman’s terminology.)
The following is multiple choice question (with options) to answer.
What are proteins that increase the rate of biochemical reactions? | [
"hormones",
"amino acids",
"enzymes",
"metabolites"
] | C | Enzymes are proteins that increase the rate of biochemical reactions. Enzymes aren’t changed or used up in the reactions, so they can be used to speed up the same reaction over and over again. Enzymes are highly specific for certain chemical reactions, so they are very effective. A reaction that would take years to occur without its enzyme might occur in a split second with the enzyme. |
SciQ | SciQ-2989 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
What process enables all living things to maintain a constant internal environment? | [
"ketosis",
"consciousness",
"homeostasis",
"peristalsis"
] | C | All living things are able to maintain a constant internal environment through homeostasis. |
SciQ | SciQ-2990 | h. Evaluate C.
i. Compute Q(7), the amount of glucose produced during the day.
Exercise 10.3.5 “Based on studies using isolated animal pancreas preparations
maintained in vitro, it has been determined that insulin is secreted in a biphasic manner in response to a marked increase in blood glucose. There is an initial burst of insulin secretion that may last 5-15 minutes, a result of secretion of preformed insulin secretory granules. This is followed by more gradual and sustained insulin secretion that results largely from biosynthesis of new insulin molecules. ” (Rhoades and Tanner, P 710)
a. A student eats a candy bar at 10:20 am. Draw a graph representative of the rate of insulin secretion between 10:00 and 11:00 am.
b. Draw a graph representative of the amount of serum insulin between 10:00 and 11:00. Assume that insulin is degraded throughout 10 to 11 am at a rate equal to insulin production before the candy is eaten, and that serum insulin at 10:00 was Iq.
CHAPTER 10. THE FUNDAMENTAL THEOREM OF CALCULUS
468
c. Write an expression for the amount of serum insulin, I(t), for t between 10:00 and 11:00 am.
Exercise 10.3.6 Equal quantities of gaseous hydrogen and iodine are mixed resulting in the reaction
which runs until I 2 is exhausted [H 2 is also exhausted). The rate at which I 2 disappears is ^°’^ 2 gm/sec. How much I 2 was initially introduced into the mixture?
a. Sketch the graph of the reaction rate, r(t) = jp^yi-
b. Approximately how much I 2 combined with H 2 during the first second?
c. Approximately how much I 2 combined with H 2 during the second second?
d. Let Q(x) be the amount of I 2 that combines with H 2 during time 0 to 2; seconds. Write an integral that is Q(x).
e. What is Q\x)l
f. Compute W'{x) for W(x) = =^.
g. Show that there is a number, C, for which Q(x) = W(x) + C.
h. Show that C = 0.2 so that Q(x) = 0.2 – g.
The following is multiple choice question (with options) to answer.
Which hormone is secreted by the pancreas in a human body? | [
"estrogen",
"progesterone",
"insulin",
"growth hormone"
] | C | The pancreas is a large gland located near the stomach. Hormones secreted by the pancreas include insulin. Insulin helps cells absorb glucose from the blood. It also stimulates the liver to take up and store excess glucose. |
SciQ | SciQ-2991 | exoplanet, gas-giants, classification
Title: Is the transition between ice giants and Jupiter-like gas giants somewhat fluid? The ice giants Uranus and Neptune are often being distinguished from Saturn and Jupiter who consist mostly of hydrogen and helium, while the ice giants have more of heavier elements than hydrogen and helium. However, is there any clear distinction or is it just that gas giants who consist of more than 50% of heavier components than hydrogen and helium are considered ice giants, or something like that?
Saturn has a little bit more ices than Jupiter but still less than two per cent. Uranus and Neptune have ices in the deeper atmosphere while their upper atmosphere is hydrogen and helium too. Do planets inbetween exist that would be hard to classify whether they are ice giants or Jupiter-/Saturn-like gas giants? The distinction between gas giants and ice giants is a distinction that works nicely in our solar system. (And don't forget the distinction between the giant planets and the terrestrial planets, which also works nicely in our solar system.) I strongly doubt that these distinctions are universal.
Just before the end of the 20th century, astronomers and physicists thought they had developed a nice and simple explanation of how the solar system formed. Then astronomers started discovering exoplanets. Lots and lots of exoplanet systems. Some of those systems utterly defied that nice and simple explanation. In addition to the oddball systems, the exoplanets appear to lie on a spectrum rather than a nice clearcut classification into terrestrial / gas giant / ice giant.
There are many issues with that nice and simple explanation from the previous century, even in our solar system. The Nice Model, the Grand Tack Model, and the Grand Attack Model are attempts at addressing those many issues. All of these models are somewhat specific to our solar system, but are also somewhat generic. The formation of a star system appears to involve more than a bit of chaos.
The following is multiple choice question (with options) to answer.
What are the gas giants mostly made of . | [
"hydrogen and carbon",
"hydrogen and helium",
"calcium and helium",
"nitrogen and helium"
] | B | The gas giants are mostly made of hydrogen and helium. These are the same elements that make up most of the Sun. Astronomers think that most of the nebula was hydrogen and helium. The inner planets lost these very light gases. Their gravity was too low to keep them and they floated away into space. The Sun and the outer planets had enough gravity to keep the hydrogen and helium. |
SciQ | SciQ-2992 | homework-and-exercises, newtonian-mechanics, classical-mechanics, forces, friction
Title: Can the kinetic friction turn to static? Lets take for example a mass pushed by some force F. The mass rests on a horizontal surface with friction. F is large enough that the object is moving and a kinetic friction force is applied on it. After some time I stop pushing the mass, from this moment till the mass stops what kind of friction works on the problem? (kinetic or static). Kinetic friction acts till the body is in motion. As soon as it stops, no friction acts on it unless pushed by an external agent with force F<= Max. Static Friction.
The following is multiple choice question (with options) to answer.
Static friction acts on objects when they are resting on what? | [
"a surface",
"their laurels",
"a pool of water",
"a single point"
] | A | Static friction acts on objects when they are resting on a surface. For example, if you are hiking in the woods, there is static friction between your shoes and the trail each time you put down your foot (see Figure below ). Without this static friction, your feet would slip out from under you, making it difficult to walk. In fact, that’s exactly what happens if you try to walk on ice. That’s because ice is very slippery and offers very little friction. |
SciQ | SciQ-2993 | acid-base, equilibrium, ph
Since $K_\mathrm{a}$ of $\ce{NH4+}$ is so small, I am disregarding the changes and substituting $2.61$ instead of $2.61 - x$.
The final answer I am getting is not the same as the answer in the back of the book which is approximately $\mathrm{pH} = 0.76$.
What is wrong with my process? The hydrogen sulphate ion is a much stronger acid than that of the ammonium ion. Thus, almost every hydronium ion in the solution comes from the dissociation of hydrogen sulphate ions.
This said, the assumption,
The following is multiple choice question (with options) to answer.
The ammonium ion is what type of acid? | [
"kaon - lowry",
"brønsted-lowry",
"normal -lowry",
"oxidized - lowry"
] | B | We can also consider the reverse reaction in the above equation. In that reaction, the ammonium ion donates a proton to the hydroxide ion. The ammonium ion is a Brønsted-Lowry acid, while the hydroxide ion is a Brønsted-Lowry base. Most Brønsted-Lowry acid-base reactions can be analyzed in this way. There is one acid and one base as reactants, and one acid and one base as products. |
SciQ | SciQ-2994 | proteins, muscles, amino-acids, protein-binding
Title: What is difference between High quality and low quality proteins I have seen in news that some bodybuilder died of taking steroids; when I went through details I learned that "low quality proteins" contributed to their death. I have studied about linkages in proteins but I don't understand what makes them stronger or weaker. So what is the difference between high quality proteins or low quality proteins? How does low quality protein affect muscular activity or growth? "Low quality" vs. "high quality" protein does not refer to anything about the linkages between amino acids in proteins. Instead, these terms are used in a nutritional context to refer to whether an individual protein source is sufficient as a sole source of protein in someones' diet.
Essential amino acids are the amino acids that humans cannot synthesize; other amino acids can be synthesized from these, but they do not need to be part of the diet. Not all sources of protein have sufficient quantities of all of the essential amino acids. Low-quality protein sources are also referred to as "incomplete" and high-quality sources as "complete."
Meat products are typically "high quality" because they contain all of the essential amino acids together. Therefore, if you subsisted on various foods but only got your protein from one animal source, you would be okay.
Some plant products do not have all the essential amino acids in large concentrations. However, if you combine protein sources from different "low quality" plant sources that together cover these deficiencies, there is no disadvantage compared to a single "high quality" source.
In the digestive process, all you take out of the proteins you eat is the individual amino acids (generally): that means that only the amino acid composition matters, not the strength or quality of the bonds between amino acids. If someone tries to tell you otherwise, they are probably just trying to sell you something.
Here is a paper that talks about some of these issues, and addresses some of the myths about balancing proteins. The quick summary is that problems develop if you get your sole protein from a source that is low in a particular essential amino acids over a long time period, but there is no need to ensure every meal contain all the amino acids.
The following is multiple choice question (with options) to answer.
Loss of muscle mass due to breakdown of structural proteins is known as what? | [
"atrophy",
"exhaustion",
"mutation",
"distrophy"
] | A | 10.6 Exercise and Muscle Performance Hypertrophy is an increase in muscle mass due to the addition of structural proteins. The opposite of hypertrophy is atrophy, the loss of muscle mass due to the breakdown of structural proteins. Endurance exercise causes an increase in cellular. |
SciQ | SciQ-2995 | galaxy, observable-universe
Title: Universe is a cluster of orbiting Galaxies? Like planets orbiting stars, solar systems and other celestial objects orbiting a blackhole in the center of a galaxy, are the Galaxies and Galaxy clusters orbiting the centre of a universe (for example : let's say the largest blackhole of the universe). There's a few things to unpick here. Clusters or groups of galaxies are tiny compared to the size of the observable universe, and while gravity acts upon all bodies, in reality the distances between galaxies mean that effect is minimal.
And as the universe is expanding, tangential velocities are insignificant, so no, galaxies are not orbiting the centre of the universe.
And the centre of the universe is undefined - there is no "largest blackhole" to be the centre.
Even where you have two galaxies coming relatively close to each other (cf Andromeda and Milky Way colliding in about 4 billion years) the effects are so localised that until collision has happened, you wouldn't say that any of the stars in each of the galaxies is orbiting their common centre.
The following is multiple choice question (with options) to answer.
Which of these is last if ordered in increasing size: galaxy, solar system, star cluster? | [
"none of these",
"star cluster",
"solar system",
"galaxy"
] | D | Compared to Earth, the solar system is a big place. Compared to the solar system a star cluster is a big place. But galaxies are bigger—a lot bigger. |
SciQ | SciQ-2996 | genetics, dna, immunology, virology
Title: Difference between viral and human genetic material I have heard that there is a difference between viral and human genetic material. What is that difference?
If I take my cells and take DNA out of them and insert only a small part of it having a sequence, say, AGTTC, and viral DNA with the same sequence, can my body distinguish between the two? If so, how? To sum up: If we are not talking about chromosome organization, nucleotide sequences and overall genome architecture (which are incomparably different in eukaryotes and [even their] viruses) the differences in the genetic material are as follows:
The following is multiple choice question (with options) to answer.
What encloses the genetic material of the virus? | [
"the capsid",
"nuclei",
"the spindle",
"mitochondria"
] | A | Diagram of a Cytomegalovirus. The capsid encloses the genetic material of the virus. The envelope which surrounds the capsid is typically made from portions of the host cell membranes (phospholipids and proteins). Not all viruses have a viral envelope. |
SciQ | SciQ-2997 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
Plant-like protists are called what? | [
"bacterium",
"yeasts",
"sponge",
"algae"
] | D | Plant-like protists are called algae. They include single-celled diatoms and multicellular seaweed. Like plants, they contain chlorophyll and make food by photosynthesis. Types of algae include red and green algae, euglenids, and dinoflagellates. |
SciQ | SciQ-2998 | human-biology, breathing
Our lungs work off of pressure. Specifically our lungs inflate by using "negative pressure" (a word I've always hated). The pressure is not actually negative it is simply lower than the surroundings. Since there is less air in your lungs the air from the atmosphere rushes in because the pressure is higher outside your lungs. This is Boyle's Law (not the pressure outside being higher, but what happens when your lungs expand). Where an increase in Volume means a decrease in Pressure (if all else remains unchanged). In fact plants pull water up using negative pressure.
However to push out the air from our lungs we supply pressure using our muscles that overcomes the outside pressure and forces the air out.
The reason you feel your breathing change is because when that train passes by you correctly observed the strong gust of wind. This gust of wind has some force behind it that normally is not in the air you are breathing from the atmosphere. It has more force which increases the air's velocity. This actually decreases the pressure, but there's no need to get into that here (Bernoulli's).
The reason it feels like your body is "fighting to breath" is because the air is traveling in a direction with some force that you need to overcome by opening up your lungs just enough to "suck" the air in with negative pressure. This is more than the pressure you usually need to produce in order to breath in air that is "still".
What is funny to think about is we don't really have a muscle that "pulls" air in, even though it feels like you are actively doing that. The air actually rushes in on its own. All you do is expand your rib cage, which your lungs are attached to (look up on how, it's actually pretty cool), thereby making inhalation occur.
Now an interesting question for you to ask yourself is why is cold air harder to breathe?
The following is multiple choice question (with options) to answer.
How do mammals ventilate their lungs? | [
"negative pressure breathing",
"negative combination breathing",
"negative atmospheric breathing",
"negative pressure vocalizing"
] | A | |
SciQ | SciQ-2999 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
Blood vessels blood pumped by the heart flows through a series of vessels known as arteries, arterioles, capillaries, venules, and veins before returning to this? | [
"brain",
"heart",
"feet",
"lungs"
] | B | CHAPTER REVIEW 20.1 Structure and Function of Blood Vessels Blood pumped by the heart flows through a series of vessels known as arteries, arterioles, capillaries, venules, and veins before returning to the heart. Arteries transport blood away from the heart and branch into smaller vessels, forming arterioles. Arterioles distribute blood to capillary beds, the sites of exchange with the body tissues. Capillaries lead back to small vessels known as venules that flow into the larger veins and eventually back to the heart. The arterial system is a relatively high-pressure system, so arteries have thick walls that appear round in cross section. The venous system is a lower-pressure system, containing veins that have larger lumens and thinner walls. They often appear flattened. Arteries, arterioles, venules, and veins are composed of three tunics known as the tunica intima, tunica media, and tunica externa. Capillaries have only a tunica intima layer. The tunica intima is a thin layer composed of a simple squamous epithelium known as endothelium and a small amount of connective tissue. The tunica media is a thicker area composed of variable amounts of smooth muscle and connective tissue. It is the thickest layer in all but the largest arteries. The tunica externa is primarily a layer of connective tissue, although in veins, it also contains some smooth muscle. Blood flow through vessels can be dramatically influenced by vasoconstriction and vasodilation in their walls. |
SciQ | SciQ-3000 | physiology, hematology
Title: What is the function of clot retraction? I am thinking how clot retraction and fibrinolysis work together.
I think that clot retraction is a process that gets clot towards fibrinolysis process.
Fibrinolysis process then lyses the clot.
However, I am not sure if it is so simple.
Some seems to be discussing about how to differentiate start of fibrinolysis from clot retraction morphologically.
So they probably seem to be at this stage similar processes visually, but not functionally.
What is the function of clot retraction? The platelets in the clot contain contractile proteins. They bring the edges of the wound together, which also reduces the chance of further bleeding. The contraction process also supports the wound healing process as it brings the ends of the wound together.
For more information see this article: "Mechanics and contraction dynamics of single platelets and implications for clot stiffening"
The following is multiple choice question (with options) to answer.
What do you call the fragments of cells involved in the clotting process that are suspended in blood plasma? | [
"hematocrit",
"platelets",
"hemoglobin",
"ironites"
] | B | |
SciQ | SciQ-3001 | amateur-observing, radio-astronomy, jupiter
Figure 2 from the Nature paper linked above.
Comparison of wave power and pitch angle distributions for the encounter on 6 September 1996 (orbital segment G2). a The distance between Ganymede and the Galileo spacecraft, b measurements of the magnetic field, c pitch angle distribution of 527–884 keV electron fluxes, d same as c but normalized by the value of fluxes at 60° local pitch angle, e dynamic spectrogram of electric field very low frequency (VLF) spectral density, f dynamic spectrogram of magnetic field VLF spectral density
The following is multiple choice question (with options) to answer.
What year did the soho spacecraft first started to operate? | [
"2006",
"1987",
"2012",
"1996"
] | D | Humans have sent spacecraft up to study our star. The SOHO spacecraft has been in operation since 1996. The craft orbits the Sun in step with Earth but closer to it. SOHO has sent back amazing images. Onboard instruments have also sent back mountains of data. The data is mostly about the Sun's outer layers. |
SciQ | SciQ-3002 | water, elements
Title: Chemical composition of seawater Is it true that the sea water is composed of about $86\%$ oxygen, $11\%$ hydrogen and $3\%$ of minerals? The chemical formula of water is $\ce{H2O}$ (two hydrogen and one oxgen) that shows that the number of hydrogen is greater than that of oxygen.
If the number of hydrogen is greater, then why does the sea water consist of $11\%$ hydrogen and $86\%$ oxygen, which is lesser than the oxygen?
The book which I am reading says which is confusing me:
... Seawater is composed of about $86\%$ oxygen, $11\%$ hydrogen and $3\%$ of minerals, consisting mainly of sodium and chlorine. The book that you're reading is measuring by mass.
If you have pure water then you would expect oxygen to make up $\frac{16}{16 + 2}\times 100\% \approx 89 \% $ by mass. Likewise, hydrogen would make up $\frac{2}{16 + 2}\times 100\% \approx 11 \% $ by mass.
The following is multiple choice question (with options) to answer.
Concentration of what, the substance left behind when ocean water evaporates, is about 3.5 percent? | [
"sugar",
"salts",
"quartz",
"hydrogen"
] | B | Dissolved mineral salts wash into the ocean. As ocean water evaporates, it leaves the salts behind. This makes the water saltier. Ocean water is about 3.5 percent salts. The main salt is sodium chloride. |
SciQ | SciQ-3003 | ros, pid, gazebo, ros-melodic, husky
I posted on two website just in case one forum is inactive.
In the future: please don't cross-post. It's not very nice, as in the best case, it leads to split discussions, but typically (and that would be the worst case) it leads to duplication (ie: waste) of effort.
Post in one place and give people time to respond to your question.
Comment by psprox96 on 2019-10-21:
Roger that. Thanks for the info.
The following is multiple choice question (with options) to answer.
What has a distinct front and back end? | [
"imipenem sphere",
"heroclix sphere",
"volvox sphere",
"hydro sphere"
] | C | The Volvox sphere has a distinct front and back end. The colony of cells can swim in a coordinated fashion. The cells have eyespots, which are more developed in the cells near the front. This enables the colony to swim towards light. |
SciQ | SciQ-3004 | biochemistry, molecular-biology, cell-biology, cell-membrane
Once you have a firm grasp on that, consider that in order for a hydrophobic molecule to reach a plasma membrane, it must already be solvated by water. The transfer of a hydrophobe from one hydrophillic environment (water) to another (head groups of the phospholipids in the plasma membrane) should be energetically negligible. The limiting step for passive diffusion across a membrane is transfer from the hydrophillic environment of the phospholipid head groups to the hydrophobic environment of their tails. In fact, the rate of diffusion across a plasma membrane increases with hydrophobicity.
The following is multiple choice question (with options) to answer.
In how many basic was can substances cross the plasma membrane? | [
"one",
"two",
"four",
"three"
] | B | If a cell were a house, the plasma membrane would be walls with windows and doors. Moving things in and out of the cell is an important role of the plasma membrane. It controls everything that enters and leaves the cell. There are two basic ways that substances can cross the plasma membrane: passive transport and active transport. |
SciQ | SciQ-3005 | photosynthesis, chloroplasts
Title: Chloroplasts in an animal cell What would happen if we inject a chloroplast organelle into an animal cell?
Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could there be photosynthesis in such a cell, or will some of the necessary mechanisms be missing? To answer your bigger question:
Yes, most of this is possible - under some conditions -, and animals and animal cells can acquire chloroplasts, and use them.
E.g.: see Elysia chlorotica whose cells actively take up chloroplasts and use them, and keep them alive (though not replicating). - Though some genes of algae are also contained in the Elysia chlorotica genome - which may be considered as partial replication.
Also there are salamanders that have replicating algae within them (since embryogenesis) - even algae (with chloroplasts) within animal cells - though here the algae might be rather understood as symbionts or "cell types", and the animal cells don't have the chloroplasts by themselves.
The following is multiple choice question (with options) to answer.
What type of cells have chloroplasts? | [
"plant cells",
"animal cells",
"human cells",
"simple cells"
] | A | Plants are multicellular eukaryotes with cell walls made of cellulose. Plant cells also have chloroplasts. In addition, plants have specialized reproductive organs. These are structures that produce reproductive cells. Male reproductive organs produce sperm, and female reproductive organs produce eggs. Male and female reproductive organs may be on the same or different plants. |
SciQ | SciQ-3006 | virology, nomenclature
Title: Why is it called "Ebola virus disease", not just "Ebola" or "Ebola disease"? Why do scientists (pretty consistently) call it Ebola virus disease, rather than just Ebola, or Ebola disease?
Many other diseases are caused by viruses, but they don't seem to have this detail of terminology. Nor do you hear the analogous terminology for bacteria.
For example:
The following is multiple choice question (with options) to answer.
What is the term for disease-causing agents, such as bacteria and viruses? | [
"pathogens",
"vaccines",
"parasites",
"spores"
] | A | The body’s first line of defense consists of different types of barriers that keep most pathogens out of the body. Pathogens are disease-causing agents, such as bacteria and viruses. These and other types of pathogens are described in Figure below . Regardless of the type of pathogen, however, the first line of defense is always the same. |
SciQ | SciQ-3007 | sensors, distance-measurement
Title: How to measure height of water I am trying to measure the height [level] of the water in a box that goes from -3°C (saltwater) with water and 150°C dry. Objects will be placed inside the box but will not take up the whole area.
I need a sensor that is robust enough to go through those temperatures and measure accurately. I was thinking of using a float switch on a worm gear, but the motor couldn't stand the heat...
What other methods/sensors are there? I also have a clear tube that runs outside of the tank meant for visually inspecting the height of the water.
Can I use a ultrasound sensor to measure water level? is a closely related question but focuses upon ultrasound. That won't work for my particular case because the contents of the box are effectively unknown. And capacitive techniques won't work either as the box will be grounded. I didn't understand quite clearly what you want, but it sounds definitely like ultrasound. Although you mention that it probably won't work, I would still try it first. Another possibility would be to use radioactive material (gamma-source). But it might be difficult to get this stuff. The radioactive type is used for measurement of fill height in bottles. Though I don't know how they do it exactly.
I recommend to contact companies, which build bottle filling machines. They probably have ready to use solutions.
Concerning the laser: Any laser should be able to do this. The cheapest should be the best suited. You don't need a high quality beam.
If this doesn't help you, please make a drawing, to make your question more understandable.
The following is multiple choice question (with options) to answer.
To figure out the height of a wave you measure the distance between the crest and what? | [
"trough",
"crater",
"core",
"drift"
] | A | The figure above also shows how the size of waves is measured ( Figure above ). The highest point of a wave is the crest . The lowest point is the trough . The vertical distance between a crest and a trough is the wave height . Wave height is also called amplitude . The horizontal distance between two crests is the wavelength . Both amplitude and wavelength are measures of wave size. |
SciQ | SciQ-3008 | human-biology, zoology, pathology
Title: Do humans contract more physical sicknesses and diseases than animals do? I wondered: If I get into the library and look into the medical section it is evident that there are thousands and thousands of different human physical diseases. But if I look into the section of animal diseases it is by no means as large as the human section.
But humans are by no means the only beings with extraordinarily cell complexity. Many other animals have an equal amount of cell complexity. So shouldn't other animals have an comparative equal amount of diseases ?
Naturally as humans we are much more interested in human physiology which would explain the discrepancy. But is there any evidence that animals, especially mammals, have not an equal amount of (still unknown) different diseases ?
Remark:
While a bit similar, this is not this question:
Why do humans seem so much more prone to disease than animals?
I am asking about the quantity of diseases, not if humans are especially prone for diseases.
ADDENDUM:
The difference between the questions is like
"Is building A more prone to fall in natural catastrophes than other buildings because it seems like it ?"
and
"How many faults have building A in comparison to other buildings ?"
A correct answer to the first question is: "We made a statistical comparison and building A is more/less/equal prone to fall in a natural catastrophe. The impression is wrong/right."
A correct answer to the second question is: "Building A has in fact a mean approximately 13 000 faults while other buildings have only 5400 faults. But the reason can be that the other building are inspected with less care." Or "No, they both have very likely something like 9000 faults".
The following is multiple choice question (with options) to answer.
Humans possess greater diversity of what type, compared to laboratory animals? | [
"pathogens",
"elements",
"lifespans",
"genetics"
] | D | |
SciQ | SciQ-3009 | measurements, data-analysis
Practically speaking, however, all real mediums of communication require the size of the string to be bounded. If you have 40 pages in a journal article to describe your results, you only have 120000 characters to capture your result (assuming roughly 3000 characters per page). This can only describe $26^{120000}$ possible outcomes, assuming the alphabet from A-Z. If there are 3 trillion trees on earth, and 20,000 pages can get produced from each tree, and you permit all of unicode ($2^{16}$ characters) rather than just A-Z, and you use all of them up for your paper you can get $2^{960,000,000,000,000,000}$ possible outcomes, which is gargantuan, but still a far cry from infinity.
It can be shown that you can develop a string to encode any real number, while still being able to do all integer arithmetic without violating any rules. However, you can't encode every real number at the same time with this trick. You have to pick the real number, and then build the system around it. In science, constructing your measurement scheme around the result after the result is acquired is considered to be poor form.
Accordingly, all physically realizable experiments map any countably infinite values into a finite space, if for no other reason than to provide a way to actually write the results down. There are, of course, plenty of other reasons to do this mapping, but this particular one is the easiest to argue from a information theory perspective.
The following is multiple choice question (with options) to answer.
What system can be used by scientists to express very small numbers? | [
"certain diffusion",
"scientific diffusion",
"similar notation",
"scientific notation"
] | D | Very small numbers can also be expressed using scientific notation. The mass of an electron in decimal notation is 0.000000000000000000000000000911 grams. In scientific notation, the mass is expressed as 9.11 × 10 -28 g. Notice that the value of the exponent is chosen so that the coefficient is between 1 and 10. |
SciQ | SciQ-3010 | genetics
I will discuss a few concepts and slowly introduce the concept of heritability in both senses.
Phenotypic trait
The phenotype is the consequence of the genotype on the world. In brief, a phenotypic trait is any trait that an individual is made of!
Quantitative trait
A quantitative trait is any trait that you can measure and ordinate, that is any trait that you can measure with numbers. For example, height is a quantitative trait as you can say that individual A is taller than individual B which is itself taller that individual C.
Variance of a quantitative trait
In a population, different individuals can have different values for a given phenotypic trait $x$. Because we are talking about quantitative traits we can calculate the variance of the trait in the population. Let's call this variance $V_P$ such as
$$V_P=\frac{1}{N}\sum_i (x_i - \bar x)^2$$
In the above equation, $x_i$ is the value of the phenotypic trait $x$ of individual $i$. $N$ is the population size (there are $N$ individuals in the population) and $\bar x$ is the average phenotypic trait $x$ in the population.
$$\bar x = \frac{1}{N}\sum_i x_i$$
What is causing phenotypic variance
Why would a population display any phenotypic variance? Why wouldn't we just look exactly the same? What explains these differences?
For some traits, we see very little variance. To consider the example the OP gave in the post, the number of arms in the human population shows very little variance. However, there is quite a bit of variance in terms of the number of IQ, in terms of height or of weight.
There are two (main) sources of variance that are underlying this phenotypic variance. The first one is the genetic variance and the second one is the environmental variance. We will call the genetic variance $V_G$ and the environment variance $V_E$.
The following is multiple choice question (with options) to answer.
An unknown genotype can be determined by observing what, the term for characteristics of the resulting offspring? | [
"phenotypes",
"clusters",
"chromosonal variations",
"abnormalities"
] | A | Consider the following example: Suppose you have a purple and white flower and purple color ( P ) is dominant to white ( p ). The white flower must be homozygous for the recessive allele, but the genotype of the purple flower is unknown. It could be either PP or Pp . A testcross will determine the organism's genotype. The unknown genotype can be determined by observing the phenotypes of the resulting offspring. If crossing the unknown dominant phenotype ( PP or Pp genotype) individual with the recessive phenotype individual produces only dominant phenotypes (no recessive), then the unknown individual is homozygous dominant. If any recessive phenotypic individuals result from the cross, then the unknown individual must carry the recessive allele, and have the heterozygous genotype. |
SciQ | SciQ-3011 | homework-and-exercises
Title: Is geothermal energy ultimately derived from solar energy? The following question is taken from 10th class science NCERT book chapter 14th.
Most of the sources of energy we use represent stored solar energy. Which of the following is not ultimately derived from the Sun’s energy?
(a) geothermal energy (b) wind energy
(c) nuclear energy (d) bio-mass.
The answer is given as (c) nuclear energy.
I understand that the wind moves because of the uneven heating of the earth by the sun. And biomass uses solar energy for photosynthesis.
How is geothermal energy ultimately derived from the sun? It is not a correct statement:
Geothermal energy comes from the heat within the earth. The word "geothermal" comes from the Greek words geo, meaning earth," and therme, meaning "heat." People around the world use geothermal energy to produce electricity, to heat buildings and greenhouses, and for other purposes.
The earth's core lies almost 4,000 miles beneath the earth's surface. The double-layered core is made up of very hot molten iron surrounding a solid iron center. Estimates of the temperature of the core range from 5,000 to 11,000 degrees Fahrenheit (F). Heat is continuously produced within the earth by the slow decay of radioactive particles that is natural in all rock
italics mine.
Geothermal energy comes from the original energy of the matter solidifying into the sun-planetary system, ultimately from the Big Bang, and from continuous nuclear decays and reactions .
The following is multiple choice question (with options) to answer.
Wind power, solar power, hydropower, and geothermal power are called renewable sources of energy or what other term? | [
"mandatory energy",
"conservative energy",
"specific energy",
"alternative energy"
] | D | Alternative energy sources include wind power, solar power, hydropower, and geothermal power. |
SciQ | SciQ-3012 | electric-circuits, batteries
Title: Why would a series of cells not be suitable for a car battery? A car battery needs to supply a current of $200A$ to turn over the starter motor. Explain why a battery made of a series of cells would not be suitable for a car battery.
My thinking:
I'm thinking it could be something to do with the internal resistances of the cells. Would that and the high current somehow result in a short circuit of the individual cells? Here is the question in context.
I'm thinking it could be something to do with the internal resistances of the cells.
Given the context, it seems reasonable to deduce that the person who wrote the question wanted you to consider the internal resistance.
In real life, car batteries are made up of a series of cells. This fact makes this question seem somewhat unrealistic and perhaps misleading or confusing. It could certainly be argued that the question was poorly chosen. However if I encountered such a question in an exam, I would try to make the best of it by proceeding along the path the question composer obviously had in mind.
Having done so there are numerous ways you could explore the subject for a fuller and more accurate understanding of the scenario.
Note that a typical 12V car-battery has six lead-acid cells. You could find out the typical internal resistance of each cell and calculate their effect on the battery as a whole.
From earlier chapters in the book, you can work out the power, in Watts, of the starter motor. You could then calculate the power dissipated in the battery's internal resistance for a one-cell, six-cell and twenty-cell battery (at 2V per cell and using whatever "typical" value you find out for internal resistance per cell)
You could also find out if the internal resistance depends on temperature or current or other factors.
The following is multiple choice question (with options) to answer.
How much electricity is generated by an average car battery? | [
"six volts",
"twelve volts",
"ten volts",
"eight volts"
] | B | The description given above describes the process that occurs in one cell of a lead-acid battery. Because cars require a battery with a higher voltage than can be obtained with a single cell, car batteries generally consist of several cells connected together to produce the desired voltage output. A typical car battery will generate twelve volts of electricity. |
SciQ | SciQ-3013 | cell-biology, development, embryology
Title: What is cytoplasmic localization? I was studying development of chick but didn't understand what is cytoplasmic localization. My book says:
After third cleavage , the rest of the cleavages are irregular and completely delimited cells are formed all over the germinal disc which is termed as blastoderm. This outcome of cleavage called cytoplasmic localization helps seal the developmental fate of each cell's descendants. "Cytoplasmic localization" is a very general term and it means that something is present in the cytoplasm. For instance (hypothetical but there are known examples), you can say protein-X is localized to cytoplasm or the cytoplasmic localization of protein-Y is reduced upon phosphorylation. Similarly, there are terms like "nuclear localization", "ER localization", "mitochondrial localization" etc.
The usage mentioned in your excerpt is actually unclear and misleading. There is no process called cytoplasmic localization. What it actually means is that there are proteins/RNA inside the cytoplasm of the embryo that are asymmetrically distributed. When the cell divides, these molecules are therefore asymmetrically sorted to the daughter cells. Depending on what (and how much of) molecules the daughter cells receive, different cells adopt different phenotypes. Also note that the axis of division also plays a role; if lets say the distribution of a given molecule is asymmetric only about the anteroposterior axis and the division happens along that axis then both daughter cells receive the same amount of molecule and both the cells would be similar (w.r.t that molecule). This won't be the case if the division is along left-right axis. See the figure below.
From: Berika et al., 2014
I am not sure which book you are following but Developmental Biology by Scott F Gilbert is a good book and explains these processes nicely.
The following is multiple choice question (with options) to answer.
What is the term for a cellular "scaffolding" that crisscrosses the cytoplasm? | [
"cytoskeleton",
"protoskeleton",
"collagen",
"cellulose"
] | A | The cytoskeleton is a cellular "scaffolding" or "skeleton" that crisscrosses the cytoplasm. All eukaryotic cells have a cytoskeleton, and recent research has shown that prokaryotic cells also have a cytoskeleton. The eukaryotic cytoskeleton is made up of a network of long, thin protein fibers and has many functions. It helps to maintain cell shape. It holds organelles in place, and for some cells, it enables cell movement. The cytoskeleton also plays important roles in both the intracellular movement of substances and in cell division. Certain proteins act like a path that vesicles and organelles move along within the cell. The threadlike proteins that make up the cytoskeleton continually rebuild to adapt to the cell's constantly changing needs. Three main kinds of cytoskeleton fibers are microtubules, intermediate filaments, and microfilaments. |
SciQ | SciQ-3014 | dna, codon
Title: Will a Codon result in same amino acid across organisms Will all organisms with the same 3 nucleotide sequence in the codon produce the same exact same amino acid. I read that the three nucleotide sequence will code for a particular amino acid. I did not understand if that is the case across organisms. Can someone explain this in simple terms. Although the answer to this question may be found in Mitochondrial Genetic code, because that answer is primarily about mitochondrial genetic codes, I shall give a more directed answer here.
Because the same genetic code that was elucidated in bacteria was found to apply to higher eukaryotes, it was initially assumed that the genetic code was universal, and was referred to as such. Subsequently it was discovered that mitochondria did not generally employ this ‘universal’ code, which is now usually referred to as the ‘standard’ code — indeed different mitochondrial codes were found in different organisms.
However the question seems to be more concerned with the genetic codes of bacteria and the nuclear genetic codes of eukaryotes. Here also there are deviations from the standard genetic code, which can be found listed either on this Wikipedia page or at NCBI.
Below are some examples from the NCBI list (where references may be found) with the standard coding in parentheses:
Mycoplasma
UGA Trp (Ter)
Ciliates, Dasycladacean and Hexamita
UAA Gln (Ter)
UAG Gln (Ter)
Euplotidae
UGA Cys (Ter)
Candidate Division SR1, Gracilibacteria
UGA Gly (Ter)
Pachysolen tannophilus
CUG Ala (Leu)
Finally, tRNAs for the ‘additional’ amino acids, selenocysteine and pyrrolysine recognize, respectively, the UGA and UAG stop codons in specific contexts.
The following is multiple choice question (with options) to answer.
What common code do all known living organisms use? | [
"code of ethics",
"biochemical",
"genetic",
"Morse code"
] | C | The genetic code is universal. All known living organisms use the same genetic code. This shows that all organisms share a common evolutionary history. |
SciQ | SciQ-3015 | theoretical-biology, population-dynamics
$$\frac{dN(t)}{dt} = rN\left(1-\frac{N}{K} \right)\left(\frac{N}{A}-1\right) \tag{strong}\label{}$$
If per capita population growth rate (dN/dtN) is plotted against population size for these two models, as well as for the standard logistic model, this is what you get:
The following is multiple choice question (with options) to answer.
What are 2 common growth patterns of population? | [
"organic and inorganic",
"exponential and logistic",
"migratory and logistic",
"exponential and economical"
] | B | Populations may show different patterns of growth. The growth pattern depends partly on the conditions under which a population lives. Two common growth patterns are exponential growth and logistic growth. Both are represented in Figure below . |
SciQ | SciQ-3016 | quantum-mechanics, wavefunction, schroedinger-equation, parity
Title: A few parity questions for simple harmonic oscillator I think I understand that the solution to the Schrodinger equation for the SHO is based on the Hermite polynomials (and the Guassian function). The solution set of all even Hermite polynomials are a solution to the Schrodinger equation, as well as the set of all odd Hermite polynomials.
Questions:
Is the set of all odd Hermite polynomials a solution because the potential $V(x)=1/2kx^{2}$ has even parity?
Does $\psi^{*}\psi$ have even or odd parity, or neither?
Why does $<x>=0$?
The following is multiple choice question (with options) to answer.
Solutions to schrödinger’s equation involve four special numbers called what? | [
"quantum numbers",
"light numbers",
"gravity numbers",
"linear numbers"
] | A | Solutions to Schrödinger’s equation involve four special numbers called quantum numbers . (Three of the numbers, , , and , come from Schrödinger’s equation, and the fourth one comes from an extension of the theory). These four numbers completely describe the energy of an electron. Each electron has exactly four quantum numbers, and no two electrons have the same four numbers. The statement that no two electrons can have the same four quantum numbers is known as the Pauli exclusion principle . |
SciQ | SciQ-3017 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
What is the only human cell with flagella? | [
"Feces",
"egg",
"sperm",
"saliva"
] | C | Sperm cells are the only human cell with flagella . This is because of their need to "swim" long distances to reach an egg for fertilization. |
SciQ | SciQ-3018 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
What can be described as a tiny male gametophyte enclosed in a tough capsule? | [
"grain of pollen",
"cell",
"dna",
"seed"
] | A | A grain of pollen is a tiny male gametophyte enclosed in a tough capsule (see Figure below ). It carries sperm to an ovule while preventing it from drying out. Pollen grains can’t swim, but they are very light, so the wind can carry them. Therefore, they can travel through air instead of water. |
SciQ | SciQ-3019 | human-anatomy, cardiology
Title: Structure separating the left atrium from the ascending aorta? With reference to the (adult) anatomy of the human heart:
The left atrium (LA) and the proximal part of the ascending aorta (Ao) abut one another, as shown nicely in this image [1]. Is there a name for the wall(s) separating the LA and Ao? And is this a single structure (i.e. septum), or is there a sinus?
[1] http://www.radiologyassistant.nl/data/bin/w440/a5097978b829cd_3-chamber.jpg There isn't any particular structure there: you have the wall of the aorta/adventitia, and if you have an explanted heart there is a space and then the auricle of the left atrium on one side and the right atrium on the other. These would all be contained within the pericardium.
Where the aorta is most "touching" the left atrium is where the pulmonary veins come in: I think this picture from Gray is most helpful.
Figure 494. Henry Gray (1825–1861). Anatomy of the Human Body. 1918.
There really isn't much to distinguish these veins from the non-auricle part of the atrium, similar to the vena cava on the right side. If you were to cut along the veins eventually you would just open up into the atrium.
The Visible Heart Lab is another good reference http://www.vhlab.umn.edu/atlas/aorta for cardiac anatomy.
The following is multiple choice question (with options) to answer.
What is the largest artery in the body called? | [
"ventricular",
"carotid",
"aorta",
"radial"
] | C | Flaps of tissue called valves separate the heart’s chambers. Valves keep blood flowing in just one direction through the heart. For example, a valve at the bottom of the right atrium opens to let blood flow from the right atrium to the right ventricle. Then the valve closes so the blood can’t flow back into the right atrium. |
SciQ | SciQ-3020 | genetics, cell-biology, embryology, meiosis, gamete
Title: Fertilization of the human egg- where does our centrosome come from? Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can have a centrosome? If this is so, then how did oogenesis happen? ? To answer the first part of your question. The sperm actually introduces two centrosomes. The centrosome then nucleates the new microtubule assembly to form the sperm aster — a step essential for successful fertilization. You can visit these sites Simerly, et al as well as Paweltz, et al
The following is multiple choice question (with options) to answer.
Fertilization occurs if a sperm enters the egg while it is passing through what tube? | [
"ovarian",
"anterior",
"fallopian",
"vaginal"
] | C | Fertilization occurs if a sperm enters the egg while it is passing through the fallopian tube. When this happens, the egg finally completes meiosis. This results in two daughter cells that are different in size. The smaller cell is called a polar body . It contains very little cytoplasm. It soon breaks down and disappears. The larger cell is the egg. It contains most of the cytoplasm. This will develop into a child. |
SciQ | SciQ-3021 | mathematical-models, blood-pressure
Title: Why can blood vessel contraction be described as a second order system?
Suppose that the x-axis represents time, and the y-axis vessel diameter.
Then this graph is claimed to roughly describe what happens when the blood pressure increases, then decreases.
When the blood pressure first increases, the vessel diameter expands to its maximum radius. Then it contracts. What I don't understand is why it keeps on expanding and contracting after its initial expansion - does this model still make sense after its initial expansion and contraction?
Can anyone explain? Many systems have this property. The plot you are looking at is the plot of the transfer function for blood vessel diameter vs time. A trick in mathematics or engineering is to understand a system is to sometimes look at at different system with the same properties that you do understand. For instance, a mass springer damper system is similar to a RLC circuit. That is, if we understand the mass spring damper system, we view the RLC circuit as the analog to the mechanical system and vice versa. In the case of blood pressure, we also have a driven force (the heart). Thus, an extremely simple model would be
$$
m\ddot{x} + c\dot{x} + kx = F(t)
$$
As we see below, the mass spring damper model produces the a similar plot of the transfer function. If you understand the mechanical system or RLC circuit, you can look at your plot parameters as an analog to one of these systems to understand the dynamics occurring in the body.
A more interesting question is can we use PID control to manage the overshoot, rise time, and settling time of the vessel diameter in the body?
The differential equation that models this process is probably related to a Bernoulli differential equation.
http://en.wikipedia.org/wiki/Bernoulli%27s_principle
page 15 http://www.physics.usyd.edu.au/~jbryant/Fluids/Fluidslect4.pdf
http://bme.ccny.cuny.edu/faculty/bfu/blood%20flow%20permeability%20in%20microvessels.pdf
A precise differential equation will need to account for pressure (Bernoulli), fluids (Navier-Stokes), and the elasticity of the vessel walls.
The following is multiple choice question (with options) to answer.
When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the what? | [
"veins",
"arteries",
"capillaries",
"bones"
] | C | |
SciQ | SciQ-3022 | evolution, herpetology, dinosaurs
Title: Evolution of dinosaurs What did dinosaurs evolve from? Was it the reptiles that evolved from amphibians? I have been researching this but am very confused with who their direct predecessor was. Amphibians evolved from fish...reptiles from amphibians...dinosaurs from reptiles (?)...and birds from dinosaurs. That is my understanding, but it could be wrong. How are dinosaurs related to reptiles? And if they did evolve from reptiles, which kind of reptiles (such as lizards, crocodiles, or turtles for example)? Source of information
See the post The best free and most up to date phylogenetic tree on the internet? for info about how to find such information.
Generally speaking, you might be interested in an intro to phylogenetics such as the one provided in this answer for example.
Where are dinosaurs in the tree of life?
Dinosaurs fall within the Reptiliomorpha clade. Please note that Reptiliomorpha does not quite correspond to what we today call reptiles. Please see the post If dinosaurs could have feathers, would they still be reptiles?
Reptiliomorpha is the sister clade to Amphibia (from here) which contain all living amphibians.
If you look within the Amniota, you will find all of the following
Here, you see that turtles and mammals are an off-shoot of Diapsida. So dinosaurs are not mammals and there are not closely related to turtles. Now if you click on Diapsida you will find ...
the Archosauromorpha which contains all crocodiles, birds and dinosaurs. You can keep going to find Therapoda which contains many dinosaurs and birds. You can keep going like this for yourself and discover the entire tree of life!
Reacting to your sentences
What did dinosaurs evolve from?
When asking this question, please do not forget that no species evolved from an extant species. If this is unclear to you, you should have a look at this post.
Was it the reptiles that evolved from amphibians?
Well... the term reptile is a mess because it does not represent a monophyletic group (see this post). If you do not understand the term monophyletic, then you should have a look at this answer.
Amphibians evolved from fish...
The following is multiple choice question (with options) to answer.
What to tadpoles develop into? | [
"toads",
"mosquitos",
"frogs",
"snakes"
] | C | Frogs typically lay their eggs in puddles, ponds, or lakes. Their larvae, or tadpoles , have gills, a tail, but no legs, and need to live in water. If fact, they are quite similar to a fish. Tadpoles develop into adult frogs in water ( Figure below ). During this transformation, they develop lungs, lose their tails and form their four legs. |
SciQ | SciQ-3023 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
What part of the body do fish use to absorb oxygen? | [
"under belly",
"dorsal fin",
"tail fin",
"gills"
] | D | In order to absorb oxygen from the water, fish use gills ( Figure below ). Gills take dissolved oxygen from water as the water flows over the surface of the gill. |
SciQ | SciQ-3024 | solutions, electrons, metal, optical-properties, solvated-electrons
This gives a great picture of what a solvated electron could look like. The point is that it can look like a lot of things. If you wish, you can think of these isosurfaces as being an "orbital" that the excess electron is free to move around in. The difference is that we draw orbitals as 90% probability densities, only these are drawn at a constant volume, and hence don't all contain the same "percentage of the electron". In fact many of these surfaces contain less than 50% of the charge density, which demonstrates these electrons are very diffuse!
Now, the arrangements where the electron is primarily inside the cluster is going to resemble a solvated electron the most. It is worth noting structures such as 20c and 20d. In these structures, the electron interacts electrostatically with the free $\ce{O-H}$ bonds. In structures such as 13a and 24b, the electron is actually bound by the dipole field of the cluster (these clusters all have large dipole moments). Because these electrons are bound by dipole interactions, they will be quite diffuse.
One way in which electrons like these are definitely not like a proton in solution is that correlation effects become very important for the behavior of these electrons. Indeed, some of the structures shown above only give a negative binding energy when correlation is included at the CI level. (See 1 for details on all this.)
Some more interesting papers on electrons bound to water clusters are 2 and [3].
So, this sets us up for thinking about fully solvated electrons (sticking with water because it's where the most work is done since water is very important). As it happens, our orital analogy applies quite nicely in liquid water. Below is the little cover art from a paper hot off the presses (2017) by Ambrosio et al.. [4]
The following is multiple choice question (with options) to answer.
The electrons in a water molecule are more concentrated around the more highly charged oxygen nucleus than around this? | [
"peroxide nuclei",
"helium nuclei",
"carbon nuclei",
"hydrogen nuclei"
] | D | We will find in Atomic Physics that the orbits of electrons are more properly viewed as electron clouds with the density of the cloud related to the probability of finding an electron in that location (as opposed to the definite locations and paths of planets in their orbits around the Sun). This cloud is shifted by the Coulomb force so that the atom on average has a separation of charge. Although the atom remains neutral, it can now be the source of a Coulomb force, since a charge brought near the atom will be closer to one type of charge than the other. Some molecules, such as those of water, have an inherent separation of charge and are thus called polar molecules. Figure ⎛ ⎞ 19.19 illustrates the separation of charge in a water molecule, which has two hydrogen atoms and one oxygen atom ⎝H 2 O⎠ . The water molecule is not symmetric—the hydrogen atoms are repelled to one side, giving the molecule a boomerang shape. The electrons in a water molecule are more concentrated around the more highly charged oxygen nucleus than around the hydrogen nuclei. This makes the oxygen end of the molecule slightly negative and leaves the hydrogen ends slightly positive. The inherent separation of charge in polar molecules makes it easier to align them with external fields and charges. Polar molecules therefore exhibit greater polarization effects and have greater dielectric constants. Those who study chemistry will find that the polar nature of water has many effects. For example, water molecules gather ions much more effectively because they have an electric field and a separation of charge to attract charges of both signs. Also, as brought out in the previous chapter, polar water provides a shield or screening of the electric fields in the highly charged molecules of interest in biological systems. |
SciQ | SciQ-3025 | thermodynamics, temperature
Title: Non uniform freezing of lakes Here's a problem from my physics textbook:
Why do lakes freeze first at the surface?
I'm not sure why this should happen, and my guess is that the only reason for this could be the temperature distribution with depth, inside water bodies. You need to know that water at $4^{\circ}$C achieve its highest density. So naturally, water at $4^{\circ}$C will tend to move to the bottom of the lake as it is heavier. When the temperature is cool enough to freeze the lake, eventually there will be some layer of ice forming at the surface but there is still liquid water below the ice layer. The ice also works as an insulation to keep the water below it from freezing to ice completely. Also, ice has a lower density than water so any ice forming will float to the surface. There are other factor like Earth's internal heating that constantly maintaining the water at the bottom of lake from freezing.
The following is multiple choice question (with options) to answer.
What is the layer of ground below the surface that is always frozen, even in the summer? | [
"upper crust",
"permafrost",
"tundra",
"bedrock"
] | B | Polar tundra climates occur near the poles. Tundra climates have permafrost. Permafrost is layer of ground below the surface that is always frozen, even in the summer. Only small plants, such as mosses, can grow in this climate. |
SciQ | SciQ-3026 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What is usually the prey of a protist? | [
"proteins",
"pathogens",
"bacteria",
"algae"
] | C | The protist wraps around its prey, which is usually bacteria. |
SciQ | SciQ-3027 | energy, waves, energy-conservation, interference, superposition
Title: What happens to the energy when waves perfectly cancel each other? What happens to the energy when waves completely cancel each other out via destructive interference? It seems like the energy just disappears, but that would violate the law of energy conservation.
My guess is that the kinetic energy is transformed into potential energy. Or maybe what happens to the energy depends on the specific interference scenario? Can someone elaborate on that or correct me if I'm wrong? Waves always travel. Even standing waves can always be interpreted as two traveling waves that are moving in opposite directions (more on that below).
Keeping the idea that waves must travel in mind, here's what happens whenever you figure out a way to build a region in which the energy of such a moving wave cancels out fully: If you look closely, you will find that you have created a mirror, and that the missing energy has simply bounced off the region you created.
Examples include opals, peacock feathers, and ordinary light mirrors. The first two reflect specific frequencies of light because repeating internal structures create a physical regions in which that frequency of light cannot travel - that is, a region in which near-total energy cancellation occurs. An optical mirror uses electrons at the top of their Fermi seas to cancel out light over a much broader range of frequencies. In all three examples the light bounces off the region, with only a little of its energy being absorbed (converted to heat).
A skip rope (or perhaps a garden hose) provides a more accessible example. First, lay out the rope or hose along its length, then give it quick, sharp clockwise motion. You get a helical wave that travels quickly away from you like a moving corkscrew. No standing wave, that!
You put a friend at the other end, but she does not want your wave hitting her. So what does she do? First she tries sending a clockwise wave at you too, but that seems to backfire. Your wave if anything seems to hit harder and faster. So she tries a counterclockwise motion instead. That seems to work much better. It halts the forward progress of the wave you launched at her, converting it instead to a loop. That loop still has lots of energy, but at least now it stays in one place. It has become a standing wave, in this case a classic skip-rope loop, or maybe two or more loops if you are good at skip rope.
The following is multiple choice question (with options) to answer.
What concentrates wave energy or disperses it? | [
"a prism",
"wave refraction",
"wave reflection",
"wave diffusion"
] | B | Wave refraction either concentrates wave energy or disperses it. In quiet water areas, such as bays, wave energy is dispersed. This allows sand to be deposited. Land that sticks out into the water is eroded by the strong wave energy. The wave energy concentrates its power on the wave-cut cliff . |
SciQ | SciQ-3028 | photosynthesis, chloroplasts
Title: Chloroplasts in an animal cell What would happen if we inject a chloroplast organelle into an animal cell?
Will the animal cell destroy it? Or is it possible that the chloroplast will somehow survive, and even replicate? Could there be photosynthesis in such a cell, or will some of the necessary mechanisms be missing? To answer your bigger question:
Yes, most of this is possible - under some conditions -, and animals and animal cells can acquire chloroplasts, and use them.
E.g.: see Elysia chlorotica whose cells actively take up chloroplasts and use them, and keep them alive (though not replicating). - Though some genes of algae are also contained in the Elysia chlorotica genome - which may be considered as partial replication.
Also there are salamanders that have replicating algae within them (since embryogenesis) - even algae (with chloroplasts) within animal cells - though here the algae might be rather understood as symbionts or "cell types", and the animal cells don't have the chloroplasts by themselves.
The following is multiple choice question (with options) to answer.
In plants and algae, photosynthesis takes place in which organelles? | [
"cells",
"fibroblasts",
"stems",
"chloroplasts"
] | D | In plants and algae, photosynthesis takes place in organelles called chloroplasts. Chloroplasts contain stacks of membranes called thylakoids, which contain chlorophyll. Thylakoids are surrounded by a fluid-filled space called stroma. |
SciQ | SciQ-3029 | waves, acoustics
Title: Can sound waves deform (curl brake) like water waves? As far as I understand, both water waves and sound waves are mechanical waves, in the sense that both are created by the relative movement of particles in a certain medium. Sound is propagation of waves in air (relative movement of air molecules), and water waves propagate in water (relative movement of water molecules).
You can see water waves to create something called a curl brake (when they tip over) as seen on the image. Since both sound waves and water waves are similar in that they both propagate on a medium, can sound waves deform, and for example create a curl brake (tip over) too?
Can sound waves deform (curl brake) like water waves? Water waves have both transverse components, where the oscillations are perpendicular to the direction of wave motion, and longitudinal components, where the oscillations are in the direction of wave motion.
In fact, water molecules follow a circular path (orbits) in water waves. When ocean waters reach shallower parts, the “orbitals” in the upper part of the wave are moving faster than those lower, and so the wave crest moves forward faster and ahead of the rest of the wave, creating the “tube” effect.
This is different to sound waves in air, in which case there exist only longitudinal oscillations in general.
So the "curl break" phenomena is not something that will occur for sound waves due to the fact that (in air) oscillations occur parallel to the direction of propagation.
You can imagine "curl break" to occur when a wave oscillates both up-and-down and in the direction of propagation like in water waves, but not for a wave that is purely longitudinal, as in sound waves (in air).
The following is multiple choice question (with options) to answer.
What produces sound waves that travel outward in all directions in water? | [
"ultrasound machines",
"echo chamber",
"echo sounders",
"amplifiers"
] | C | During World War II, battleships and submarines carried echo sounders. Their goal was to locate enemy submarines ( Figure below ). Echo sounders produce sound waves that travel outward in all directions. The sound waves bounce off the nearest object and then return to the ship. Scientists know the speed of sound in seawater. They then can calculate the distance to the object that the sound wave hit. Most of these sound waves did not hit submarines. They instead were used to map the ocean floor. |
SciQ | SciQ-3030 | 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.
The roots of a plant take in nutrients and what vital substance? | [
"air",
"water",
"Soil",
"Ash"
] | B | |
SciQ | SciQ-3031 | biochemistry, botany, plant-physiology, photosynthesis
Title: Independence of Light independent reaction in photosynthesis? Inspired by a question asked to me by a classmate, I have the following question about Light-independent (dark phase) reactions in photosynthesis:-
Let us suppose an algae sample was exposed to light for a considerable
time so that maximum( if there is a limit) NADPH concentration was
achieved. Now if the sample is placed in dark and radioactive
¹⁴CO₂ bubbled, will the cell be radiolabelled after some time of
bubbling continuously?
The following is multiple choice question (with options) to answer.
Carbon fixation is the first step of what cycle involving light reactions? | [
"life cycle",
"water cycle",
"sun cycle",
"calvin cycle"
] | D | As Melvin Calvin discovered, carbon fixation is the first step of a cycle. Like an electron transport chain, the Calvin Cycle, shown in Figure below , transfers energy in small, controlled steps. Each step pushes molecules uphill in terms of energy content. Recall that in the electron transfer chain, excited electrons lose energy to NADPH and ATP. In the Calvin Cycle, NADPH and ATP formed in the light reactions lose their stored chemical energy to build glucose. |
SciQ | SciQ-3032 | molecules, polarity
Title: Non polar molecular and attractive forces How come when a non polar molecule increases in size, the attractive forces between the molecules of a substance also increase?
I thought that when a molecule increases in size, the atomic radius increases, which creates a bigger space between particles; thus, the force of attraction would be weaker.
But, why does the force of attraction increase when a non polar molecule increases in size? There is more than one factor that matters in the forces between molecules. The tradeoff between these different factors is complex and can't be reduced to a single simple equation or factor. So some of the factors become more important because of molecular or atomic size counterbalancing the factor of distance between the entities.
The collective force that cause molecules and atoms to attract are often referred to as van der Waal's force (though some sources use a more narrow definition that doesn't include all of the components below). The key non-bonding forces involved are:
forces between permanent dipoles
forces between permanent dipoles and induced dipoles
forces between instantaneously induced dipoles caused by quantum fluctuations
In non-polar molecules it is the third of these that dominates. Crudely stated the force arises because of uneven distribution of the electron cloud in a molecule or atom that happens as a result of quantum fluctuations in the cloud. An uneven distribution of electron density is the equivalent of a dipole moment. These dipole moments create induced dipoles in neighbouring atoms and can interact with other quantum fluctuations in the neighbouring atoms. These create small electrostatic forces between the atoms or molecules.
The reason why larger atoms or molecules seem to have larger forces is two fold. Larger molecules, crudely, have larger electron clouds and more ways to interact (shape matters too and large flat molecules "stick" together more than irregular lumpy ones: compare the melting points of benzene and toluene).
In larger atoms the explanation is simpler. Larger electron clouds are less tightly held by there nuclei than those in smaller atoms. Crudely, larger, floppier clouds can have more scope for the quantum fluctuations than tighter-held smaller clouds (also they have a larger area and that maters to the total force). So the size effect increases the strength of the force rather than reducing it as might be expected from simpler arguments.
The following is multiple choice question (with options) to answer.
What are the attractive forces that occur between polar molecules called? | [
"ion-dipole forces",
"induced-dipole forces",
"dipole-dipole forces",
"particle - dipole forces"
] | C | Dipole-dipole forces are the attractive forces that occur between polar molecules. A molecule of hydrogen chloride has a partially positive hydrogen atom and a partially negative chlorine atom. In a collection of many hydrogen chloride molecules, they will align themselves so that the oppositely charged regions of neighboring molecules are near each other. |
SciQ | SciQ-3033 | dna, gene-expression
Title: Complexity in creating transgenic animals (e.g., mice) Many papers I have seen describing transgenic rodent models (and presumably applicable to other model organisms) involve the knock-in, or modification to, a single gene, possibly two genes. With respect to recombineering techniques, what prevents targeting multiple genes in a single organism? For instance, if I wanted to simultaneously knock-in some genes and knock-out others within the same mouse, would I be forced to generate individually modified transgenic lines and then do some "fancy" breeding to generate the multiple-modified mice? One reason is the low likelihood of success. Modifying a gene almost always involves a recombination event of plasmid DNA with a target site in the genome (and I say almost just because there may be some method that I don't know about, but all the ones I'm familiar with do). The likelihood of that decreases exponentially with the number of genes you're trying to modify. If you're trying to make several mutants of individual genes the likelihood of success decreases only linearly.
Another reason is having more knowledge and experimental power. You can learn little from a double mutant if you don't also have the individual mutants to compare. In fact, most reviewers would ask for individual mutant data if you've made a double mutant in your paper. This is especially true with flies and worms, as crosses take less time with them.
Also, the more mutant genes you have, the weaker the animal. Your mutants may not be viable at all with too many mutations.
The following is multiple choice question (with options) to answer.
The production of multiple copies of a single gene is called? | [
"gene cloning",
"gene variation",
"cell cloning",
"gene change"
] | A | |
SciQ | SciQ-3034 | organic-chemistry, synthesis, plastics, fuel
Title: Can plastic be used as fuel for vehicles? I don't have much of a background in chemistry, but I know that plastics are largely made of carbon, as is oil. Is there any way to "covert", i.e. a plastic water bottle, into a substance that can be used as fuel for ? Thanks. There are many ways to recycle different types of plastic, and conversion to liquid fuels suitable for internal combustion engines is currently done on an industrial scale. The key to converting the carbon contained in long-chain polymers that make up the plastics is called pyrolysis, which is essentially a way to thermally decompose these products into shorter chain hydrocarbons suitable for use as liquid (or even gaseous or solid) fuel. According to this Wikipedia article:
Anhydrous pyrolysis can also be used to produce liquid fuel similar to diesel from plastic waste, with a higher cetane value and lower sulfur content than traditional diesel.
An example of a current commercial waste-plastic-to-fuel operation is the Canadian corportion Plastic2Oil, Inc., who claims to "convert waste plastic to ultra clean oil" in their 250,000 gallon fuel production and blending facility.
The following is an excerpt from the description of the patent-pending process used by Plastic2Oil:
The following is multiple choice question (with options) to answer.
Fossil fuels are made out of what two objects? | [
"soil and animals",
"plants and water",
"gases and animals",
"plants and animals"
] | D | Fossil fuels are made from plants and animals that lived hundreds of millions of years ago. The plants and animals died. Their remains settled onto the ground and at the bottom of the sea. Layer upon layer of organic material was laid down. Eventually, the layers were buried very deeply. They experienced intense heat and pressure. Over millions of years, the organic material turned into fossil fuels. |
SciQ | SciQ-3035 | species-identification, theoretical-biology, taxonomy, literature, bioluminescence
Title: Looking for the closest example of life forms similar to some mathematical patterns
Caveat: this is my first question here, it is quite interdisciplinary, but I hope to be in the correct place to ask. I am a user of Mathematics Stack Exchange since some years ago, and this question is related with some questions there (here, here whose general formula is discussed here and here).
Context: I am preparing a mathematical paper regarding a new family of dynamical systems (if you are not familiar with the concept, simplifying the idea it is a mathematical formula in which starting from a initial value, once applied to the formula the resulting value is again applied to the formula, and so on, finally the values are plotted and eventually a -sometimes interesting- pattern emerges) whose attractors (plotted patterns) in the present case seem to have unexpected pareidolic properties.
Basically some of the patterns generated by these systems show similarities with some structures of invertebrate life forms, specially insects, marine jellyfish, and zooplancton and also due to the patterns of the accumulation of points, also with life forms presenting bioluminescence properties.
For each interesting pattern so far I have tried to find the closest life form example, to compare both the model and the life form patterns.
So my target is including in the paper the closest life form similar to each mathematical pattern. Initially it is just a pareidolic coincidence, but it might be interesting if the mathematical formula can resemble models of some organic structures.
These are the ones I have been able to gather, both the model and the closest life form I found. The pictures I am using at the right side of and below the images are just for the sake of completeness (they belong to their respective owners, I do not own them, if there is any problem I will remove them, so just please let me know). The formula can be verified at the MSE links I have added at the beginning of the question and the Python code to generate them is in this link (please feel free to use it and modify it). The questions are after the examples (click to enlarge):
Patterns similar to thorax and abdomen of Bembicini wasp, head and body of Turritopsis dohrnii (inmortal jellyfish) and Tardigrade limbs:
Patters similar to Drain fly:
The following is multiple choice question (with options) to answer.
Amoebas and paramecia are examples of what? | [
"protists",
"vertebrates",
"bacteria",
"protozoa"
] | D | Examples of protozoa include amoebas and paramecia. |
SciQ | SciQ-3036 | microbiology, bacteriology, photosynthesis
2H+ + 2e– → H2
So that the overall reaction becomes:
2H2O + hν → 2H2 + O2
(Of course, this will be at the expense of energy and reducing power for carbohydrate synthesis.)
Using Hydrogenase for the Catalysis
The enzyme, hydrogenase, can catalyse the reduction of hydrogen ions shown above. This enzyme is rare in eukaryotes and absent from higher plants. It is thought to be very ancient, and may have originally been involved in energy generation from hydrogen in early evolution. One of the roles it plays in contemporary organisms is in reoxidizing NADH generated during certain fermentations in bacteria such as the Clostridium family — hydrogen is the gas produced in gas gangrene caused by Clostridium perfringens.
Certain photosynthetic organisms — notably the microalga, Chlamydomonas reinhardtii, and the photosynthetic cyanobacteria — also contain a hydrogenase in their chloroplasts. The activity of this is generally low, but appears to be coupled to photosynthesis in certain circumstances. This is through the reduced ferredoxin produced at PSI transferring its electron to the iron or iron–nickel centre of the hydrogenase:
The following is multiple choice question (with options) to answer.
Name the bacteria that make food through photosynthesis and release oxygen into the air? | [
"cyanobacteria",
"fusobacteria",
"algae",
"phytoplankton"
] | A | Bacteria called cyanobacteria are very important. They are bluish green in color (see Figure below ) because they contain chlorophyll (but not chloroplasts, of course). They make food through photosynthesis and release oxygen into the air. These bacteria were probably responsible for adding oxygen to the air on early Earth. This changed the planet’s atmosphere. It also changed the direction of evolution. Ancient cyanobacteria also may have evolved into the chloroplasts of plant cells. |
SciQ | SciQ-3037 | newtonian-mechanics, classical-mechanics, torque
Please tell me if I need to provide any further clarifications, and thanks in advance for all the help! First off you can look at half the bar, with a symmetry constraint. From the middle (I call point A) the fulcrum (point B) is located a distance $b$ such that $d =\frac{\ell}{2}-b$. The beam has uniform weight distribution $w = \frac{m g}{\ell}$ and we consider the weight supported by the fulcrum force $B_y$.
The following is multiple choice question (with options) to answer.
What simple machine consists of a bar that rotates around a fixed point called the fulcrum? | [
"catapult",
"battering ram",
"rotor",
"lever"
] | D | A lever is a simple machine that consists of a bar that rotates around a fixed point called the fulcrum. There are three classes of levers. Depending on its class, a lever may have an ideal mechanical advantage that is less than, equal to, or greater than 1. First-class levers also change the direction of the input force. |
SciQ | SciQ-3038 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
Which carbohydrate is produced by photosynthesis? | [
"sugar",
"insulin",
"protein",
"glucose"
] | D | Glucose is the carbohydrate produced by photosynthesis. Energy-rich glucose is delivered through your blood to each of your cells. |
SciQ | SciQ-3039 | geodesy
Title: Is there a name for the great circle where latitude and longitude are equal? Is there a name for the great circle where latitude and longitude are equal? I have attempted a google search but only the equator and the prime meridian are defined in the sources I can find. ( It is of relevance in developing a map application which keeps track of latitude and longitude ). The curve where latitude and longitude are equal is not a great circle. But as joe khool writes in his excellent answer, it's called the curve of Viviani! It's easy to see that the curve is not a great circle, because, using naïve spherical coordinates (in radians) $(\phi,\lambda)$ with $\lambda$ being longitude and $\phi$ being latitude (zero at equator), this curve passes through $(0,0)$, and also through $(\pi/2,\pi/2)$ which is the north pole ($(\pi/2,\lambda)$ is the north pole for any $\lambda$), But it also passes through, say, $(1,1)$ which is not on the great circle the between previous two points.
In fact the curve you get looks like this:
Note. I plotted this by defining Cartesian coordinates in the obvious way:
$$
\begin{align}
x &= R\cos\phi\cos\lambda\\
y &= R\cos\phi\sin\lambda\\
z &= R\sin\phi
\end{align}$$
and then plotting $(x,y,z)$ for $\phi = \lambda$ and $\lambda\in[-\pi/2,\pi/2]$.
An earlier version of this answer plotted $(x,y,z)$ for $\phi = \lambda$ and $\lambda\in[-\pi,\pi]$. This means that $\phi$ takes values which are not in $[-\pi/2,\pi/2]$ of course. I had assumed that these points would end up around the back of the planet: that you'd get a kind of 'S' which wraps around the planet, but in fact it ends up around the front of it again:
This surprised me!
The following is multiple choice question (with options) to answer.
What term is used to describe the line of latitude right in the middle of the planet? | [
"Prime Meridian",
"pole",
"orbital",
"equator"
] | D | Lines of latitude circle around Earth. The equator is a line of latitude right in the middle of the planet. The equator is an equal distance from both the North and South Pole. If you know your latitude, you know how far you are north or south of the equator. |
SciQ | SciQ-3040 | human-biology, human-anatomy
Title: Difference between the spinal cord and vertebrae column What is the difference between the spinal cord and the vertebrae column, they both run through from the head to the abdomen. Does any one have any idea. The vertebral column is a bony, segmented structure that supports the torso/head and thorax. The spinal cord is a bundle of nerves that runs inside the structure of the vertebral column. So - they run together, but are completely separate.
The following is multiple choice question (with options) to answer.
What is the opening formed between adjacent vertebrae for the exit of a spinal nerve called? | [
"intervertebral foramen",
"sympathetic ganglion",
"inferior vertebral notch",
"spinous process"
] | A | Figure 7.24 Intervertebral Disc The bodies of adjacent vertebrae are separated and united by an intervertebral disc, which provides padding and allows for movements between adjacent vertebrae. The disc consists of a fibrous outer layer called the anulus fibrosus and a gel-like center called the nucleus pulposus. The intervertebral foramen is the opening formed between adjacent vertebrae for the exit of a spinal nerve. |
SciQ | SciQ-3041 | planet, solar-system
Title: Considering our methods of exploration, how likely is it that there are unfound planets (not dwarf planets) in our solar system? I think it's probably unlikely that there are more planets between Mercury and Mars, but out from Jupiter, there's lots of empty space between the planets. Could there be some small planet hidden out there? There are no undiscovered planets between the sun and Neptune.
Objects closer (to Sun) than Neptune that are large enough to be considered planets (and not dwarf planets) can't remain 'hidden'. If it's there, the light from the sun will bounce off it and we will see it. As it moves in its orbit, we will notice the position in the sky change, so we will know it isn't a star.
I would like to give a more broad answer to this question though:
What is the maximum size of an undiscovered solar system object and how does it change as you get further from the sun?
The further out a solar system object is, the harder it is to detect. The rate at which it gets harder is severe; the light we receive from an object scales roughly as $1/r^4 $.
($1/r^2$ for the light travelling from the Sun to the object, and again, $1/r^2$ for the light travelling from the object to us on earth).
We are able to detect some very small earth-crossing asteroids. Some as small as ~50 metres across. At a guess (and this is just based on my intuition, not any calculations), there are probably no undiscovered objects larger than 1 km close to earth.
As you travel to the outer solar system (Jupiter to Neptune), the number of bodies increases dramatically. There are currently ~700,000 known solar system bodies and most of them occur in this area. It is believed that all asteroids larger than 10 km have been found.
The following is multiple choice question (with options) to answer.
What two planets is the asteroid belt found between? | [
"mars and venus",
"saturn and uranus",
"mars and jupiter",
"earth and venus"
] | C | Hundreds of thousands of asteroids have been found in our solar system. They are still being discovered at a rate of about 5,000 new asteroids per month! The majority are located in between the orbits of Mars and Jupiter. This region is called the asteroid belt , as shown in Figure below . There are many thousands of asteroids in the asteroid belt. Still, their total mass adds up to only about 4 percent of Earth’s Moon. |
SciQ | SciQ-3042 | periodic-trends, ionization-energy
Title: Ionization energy of neon vs its cationic counterpart
Which requires more ionization energy: $\ce{Ne}$ or $\ce{Ne+}?$
It seems to me like it should be neon because of noble gas configuration, but the answer given is $\ce{Ne+}.$ Does this anything to do with size of the atom shrinking?
Is this because cationic counterparts always have more ionization energy than their neutral counterparts because it becomes successively more difficult to remove electrons from atoms on successive removals?
Does this anything to do with size of the atom shrinking?
Yes, precisely; this is one way of putting it. Another way is to say that because one electron has been removed, the remaining electrons are less shielded from the nuclear charge: therefore, the effective nuclear charge increases, and the remaining electrons are harder to remove.
Is this because cationic counterparts always have more ionization energy than their neutral counterparts because it becomes successively more difficult to remove electrons from atoms on successive removals?
Yes. This is true for every element in the Periodic Table, with no exceptions, and it doesn't matter what the electronic configuration is.
If all else were equal, then it would indeed be harder to remove an electron from a noble gas configuration than a non-noble gas configuration. However, that is a very big if! Between $\ce{Ne}$ and $\ce{Ne+}$, the electron configurations are indeed different, but all else is not equal: as discussed previously, the effective nuclear charge in $\ce{Ne+}$ is greater than that in $\ce{Ne}$.
The following is multiple choice question (with options) to answer.
Neon is an example of what kind of gas? | [
"natural",
"noble",
"inert",
"ideal"
] | B | Once we reach neon, a noble gas, all of the 2p orbitals will be completely full. Neon has a configuration of 1s 2 2s 2 2p 6 . Any further electrons will need to go in the next highest energy orbital, which would be the 3s orbital. |
SciQ | SciQ-3043 | evolution
Title: Is there any genetic similarity that defy evolution theory? For example,
say species A is common ancestor of B, and C. Species B is a common ancestor of D and E.
We would expect that there will be more genetic similarity between D and E than D and C. And those genetic similarity must exist in B.
In other word, we won't expect genetic similarity that don't "cross" the common ancestor or the evolutionary tree.
The exception is probably genetically engineered bacteria.
That being said, am I correct?
Some people say that we have similarity with pigs and chimps even though our common ancestors may be to far off. That won't happen right?
To summarize
I expect that evolutionary tree will form a well, tree. Genetic similarity would infect "nearby" trees and can't jump between trees without connectors, such as common ancestors.
Is that what we observe for ALL species? You have an excellent answer from Remi.b already but I just wanted to add/emphasise this (because there is always more than one way of explaining something and IMO the site benefits from having many answers to the questions)...
The tree we construct does not necessarily accurately reflect what happened in evolution. If B & C evolved from A, and D & E came from B, we would create this tree if we measured using the correct indicator. But the methods we have are not perfect. The first evolutionary trees were based on morphological descriptions etc. and clearly some of the classifications were going to be wrong. These days we use molecular methods, which are probably more accurate but could also be wrong some times. For example if we based our phylogeny on one SNP variant we could have some idea about the phylogeny between a few species, but if we based it on millions of SNPs we would have a much better idea - as technology & models improve that is becoming more realistic. The key point here being there is a difference between the trees we can draw from evidence, and the real evolutionary tree.
The following is multiple choice question (with options) to answer.
Many organisms look very similar to other organisms because they may be from the same what? | [
"area",
"nutrients",
"parasites",
"species"
] | D |
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