source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3144 | planet, natural-satellites
Asteroids are sometimes found orbiting one another and I rarely hear that defined as a central asteroid with a smaller asteroid orbiting it, it's more often called a binary asteroid. I've never heard it called a baby asteroid orbiting it's parent, but again, definitions fall into a grey area if one asteroid is quite a bit larger than the other.
This XKCD comic addressed circumbinary orbits and "the other kind", which doesn't have a name. Not everything needs a name, and in this case, I don't there is an official one. "Central body" "Central object" or "Parent" work just fine as familiar and common terms.
The following is multiple choice question (with options) to answer.
What is an object that orbits a larger object called? | [
"satellite",
"comet",
"asteroid",
"meteorite"
] | A | One of the first uses of rockets in space was to launch satellites. A satellite is an object that orbits a larger object. An orbit is a circular or elliptical path around an object. Natural objects in orbit are called natural satellites. The Moon is a natural satellite. Human-made objects in orbit are called artificial satellites. There are more and more artificial satellites orbiting Earth all the time. They all get into space using some sort of rocket. |
SciQ | SciQ-3145 | energy, visible-light, photons, atomic-physics, absorption
Why is it that the electron loses energy when it jumps to the next energy level
Let's take the common usage of the word jump as upwards. So in this above case, the electron gains energy. It loses energy when it falls back down to a lower level.
I have to admit that I don't like using words like jump and fall, because they are based on the Bohr model of the atom, which is not correct in almost every aspect.
So let me give you two pictures, one of the old model, which your question is based on, and one of the more modern picture.
The Bohr model (of 100 years ago)
The Orbital Distribution Density model
The electron will tend to lose energy if it can, by emitting a photon of the correct wavelength, that enables it to transition to a lower energy level, but if that lower level is already occupied to the maximum amount, then the electron is forced to stay at a higher level.
The difference between the pictures is the the Bohr model assumes a particle structure, whereas we now think in terms of the probability of finding an electron in a certain region, so we cannot be as definite as in the earlier model. Also, when the transition from one level to another occurs, it is not a smooth transfer like a car changing lanes, it is for a time a more chaotic operation, with the electron (or rather its' likelyhood of being found) bouncing around the place until it settles into a lower orbit.
In the first example the electrons moving with current gives energy to the electron in the atom. So the electron in the atom absorbs the moving electron? If so how is this possible because they are both negative?
There is no question of an electron absorbing another electron. Instead, by means of photon emission, momentum can be transferred between electrons, bearing in mind the conservation laws regarding energy and momentum.
An example of this is a Feynman Diagram:
Where the wavy line represents energy and momentum being transferred by means of a photon.
The following is multiple choice question (with options) to answer.
When atoms gain or lose electrons, what is formed? | [
"gas",
"molecules",
"crystals",
"ions"
] | D | As we saw in the previous chapter, ions are formed when atoms gain or lose electrons. If an atom loses one or more electrons, the resulting ion has a positive charge (more protons are present than electrons). If the atom gains one or more electrons, the resulting ion has a negative charge (more electrons are present than protons). Positive ions are called cations, and negative ions are called anions. Because opposite charges attract one another, cations and anions are held together by strong electromagnetic forces. An ionic compound consists of a large three-dimensional array of alternating cations and anions. For example, sodium chloride (NaCl) is composed of Na + and Cl - ions arranged into a structure like the one shown in Figure below . |
SciQ | SciQ-3146 | circulatory-system, lymphatic-system, veins
Title: How does most of lymph get back into the blood stream? (I don't mean the lymphatic system) I once read that it was because of osmotic pressure that it returns to the blood stream, by entering the venules. But why? If lymph originated as plasma how come that the solute concentration is higher in the venule? Doesn't plasma contain solutes such as salts, nutrients, oxygen, etc. ? Technically 'lymph' is used to refer to the fluid found within the lymphatic system. If it's not in the lymphatic system, it is not lymph fluid. Thus, your question is really asking about interstitial fluid or the plasma that was filtered out of blood capillaries.
The answer to your question is based on the Starling equation. Normally fluid leaves a capillary due to a net pressure that favors the interstitium. This net pressure is based on the hydrostatic pressure within the capillary being greater than the interstitial pressure of the surrounding tissues, and the oncotic pressure of the capillary (that draws fluid in) being weaker than the hydrostatic pressure of the capillary (that pushes fluid out). At the venule end of this system, the capillary oncotic pressure is stronger than the capillary hydrostatic pressure, drawing fluid back into the circulatory system.
Remember that albumin is the most important component which establishes the oncotic pressure within a vessel, and that this protein is normally NOT released out of a vessel during filtration. Thus, it passes from the capillary into its corresponding venule directly.
The following is multiple choice question (with options) to answer.
Lymph capillaries collect the fluid that leaks from blood capillaries and slowly return it to what system? | [
"circulatory",
"muscular",
"gastrointestinal",
"cardiovascular"
] | D | Courtesy of the U. S. National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) Program. Lymph capillaries collect the flood the leaks from blood capillaries and is slowly returned to the cardiovascular system . |
SciQ | SciQ-3147 | muscles, lungs, human-physiology
Title: Why is there smooth muscle in our bronchioles? Having muscle tissue in our bronchioles that can constrict seems like a poor choice for tissue. Why would our airway want to ever close up? Wouldn't it be more beneficial for our bronchioles to just remain open? There are at least two things to consider.
First, ability to limit airflow is a defense mechanism for animal. Imagine getting into area of some sort of toxic evaporation, e.g. CO2 cloud near volcano , then it makes sense to decrease delivery of toxin via lungs to minimum. As I understand, that is what an allergic asthma attack. (Sorry for not providing good enough source of that)
Secondly, you are incorrect in assuming that normal state is "dilated". Dilation of branchioles is sympathetic ("fight-and-fly") response of the nervous system to something like danger, that requires short-term boost in energy production. That is, by default, your airflow is limited. Probably, to limit amount of energy you effectively burn via oxygenation. But most importantly, you leave yourself a reserve in terms of oxygen supply for critical moments.
Some more information you might find here.
The following is multiple choice question (with options) to answer.
Asthma affects what tiny branches into which the bronchi are divided? | [
"cilia",
"platelets",
"macrophages",
"bronchioles"
] | D | Asthma is a chronic illness in which the bronchioles, the tiny branches into which the bronchi are divided, become inflamed and narrow ( Figure below ). The muscles around the bronchioles contract, which narrows the airways. Large amounts of mucus are also made by the cells in the lungs. People with asthma have difficulty breathing. Their chests feel tight, and they wheeze. Asthma can be caused by different things, such as allergies. Asthma can also be caused by cold air, warm air, moist air, exercise, or stress. The most common asthma triggers are illnesses, like the common cold. Asthma is not contagious and cannot be passed on to other people. Children and adolescents who have asthma can still lead active lives if they control their asthma. Asthma can be controlled by taking medication and by avoiding contact with environmental triggers for asthma, like smoking. |
SciQ | SciQ-3148 | organic-chemistry, reaction-mechanism, redox
Aldehydes are very easily oxidized to carboxylic acids, and thus the aldehydes formed in the cleavage reaction do not survive. They are rapidly transformed into carboxylic acid groups, by a complex reaction whose mechanism you need not worry about.
Now, if the alkene had not had any hydrogens attached, the product in that case would have been a ketone
rather than an aldehyde. Ketones are not easily oxidized further, and the reaction would have stopped at that
stage.
If one of the alkene carbons had a hydrogen substituent, while the other did not, then we would get both acid
and ketone groups in our product, as shown below.
The following is multiple choice question (with options) to answer.
The difference between aldehydes and ketones is the placement of what group within the molecule? | [
"ammonia",
"benadryl",
"carbonyl",
"nucleus"
] | C | The difference between aldehydes and ketones is the placement of the carbonyl group within the molecule. An aldehyde is an organic compound in which the carbonyl group is attached to a carbon atom at the end of a carbon chain. A ketone is an organic compound in which the carbonyl group is attached to a carbon atom within the carbon chain. The general formulas for each are shown below. |
SciQ | SciQ-3149 | optics, geometric-optics
Title: In this ray diagram, a plane mirror seems to form a real image In this ray diagram the image formed seems to be real with the given position of the eye. I have learnt that plane mirrors cannot form real images at any circumstance. But at this one it does. Please explain the answer like I'm 5 and how you deduced what you propose. Farcher's answer is correct. But it can be elaborated a bit to make it easier to understand.
If you observe the above ray diagram for real images, you can see that the real images are formed when rays from the same point of an object intersect to form an image.
As your image shows, this is not the case. Rays from the top and bottom of the object intersect at the eye. Hence the image formed is not real.
As Farcher's modified image shows, the rays from the same point never intersect, but diverges. Hence the image formed is virtual.
The following is multiple choice question (with options) to answer.
A plane mirror has a flat reflective surface and forms only which kind of images? | [
"spherical",
"enlarged",
"reduced",
"virtual"
] | D | Most mirrors are plane mirrors. A plane mirror has a flat reflective surface and forms only virtual images. The image formed by a plane mirror is also life sized. But something is different about the image compared with the real object in front of the mirror. Left and right are reversed. Look at the man shaving in Figure below . He is using his right hand to hold the razor, but his image appears to be holding the razor in the left hand. Almost all plane mirrors reverse left and right in this way. |
SciQ | SciQ-3150 | statistical-mechanics, atmospheric-science, density
A limnic eruption, also referred to as a lake overturn, is a rare type of natural disaster in which dissolved carbon dioxide (CO2) suddenly erupts from deep lake waters, forming a gas cloud that can suffocate wildlife, livestock and humans. Such an eruption may also cause tsunamis in the lake as the rising CO2 displaces water. Scientists believe earthquakes, volcanic activity, or explosions can be a trigger for such phenomenon. Lakes in which such activity occurs may be known as limnically active lakes or exploding lakes.
Picture 1: one of a number of cattle killed by a limnic eruption at Lake Nyos, Cameroon.
We can occasionally prevent the buildup of carbon dioxide by degassing the body of water.
Picture 2: a siphon used by French scientists to de-gas Lake Nyos. The carbon dioxide emerges from its deposits and bubbles into the water, floating to the top.
The following is multiple choice question (with options) to answer.
Dissolved fertilizer can ultimately lead to the creation of what in lakes or coastal oceans, which means a place where nothing can live? | [
"extinction zone",
"dead zone",
"hydrothermal vent",
"deceased zone"
] | B | Chemicals that are applied to farm fields include fertilizers and pesticides. Excess chemicals can be picked up by rainwater. The chemicals can end up in streams, ponds, lakes, or the ocean. Dissolved fertilizer causes tremendous numbers of water plants and algae to grow. This can lead to dead zones where nothing can live in lakes or the coastal oceans. |
SciQ | SciQ-3151 | nuclear-physics, astrophysics, sun, fusion, stellar-physics
Basically, the Sun is a ball of hydrogen and helium, but this is not all there is. Being a Population I star, the Sun contains heavier elements (called metals in stellar astrophysics; anything lithium and heavier is considered metal in this sense). These elements already came with the gas cloud the Sun has formed from, and were produced by previously burst older stars. Despite low abundance, the metallicity plays an important role in the Sun's core power stability.
At some depth the gas ball compresses its inner area enough to heat it up so much that hydrogen fusion into helium begins. This area is called the core. This is where practically all fusion happens, and what is responsible for the star's energy production. For a Sun-mass star and below, the proton-proton chain dominates. The pp-chain energy output is approximately proportional to $T^4$. The good news is, if reaction rate drops, then the outer layer of the star will compress the core, so it heats up, and the renewed energy output compensates for the compression. So this highly-sensitive dependency on the temperature is what gives the star its long term stability.
It is also notable that the center of the core is hotter and therefore more energetic than its periphery, and turns hydrogen into helium faster. Absent any mixing, the core would develop an inert helium ball in the middle (helium cannot be fused by a Sun-mass star, its core is too cold for that): A pp-chain core is entirely non-convective. However, there is another multistage reaction that fuses protons into helium nuclei, the CNO cycle. This cycle requires metals ($C$, $N$ and $O$, naturally) be present in the core. They are not consumed, but participate in stages of the reaction and are ultimately recycled. The rate of this reaction depends on the temperature as $T^{20}$. It's a huge dependency! The CNO-dominant core has so much temperature gradient that it's fully convective, so it mixes the material very thoroughly.
The following is multiple choice question (with options) to answer.
When the hydrogen is nearly used up, the star can fuse which element into heavier elements? | [
"oxygen",
"carbon",
"helium",
"xenon"
] | C | Within a nebula, there are varying regions where gravity has caused the gas and dust to clump together. The gravitational attraction of these clumps pull more atoms into the clump. As this accretion continues, the gas pressure increases and the core of the protostar gets hotter and hotter. If the protostar gets dense enough and hot enough, a fusion reaction will ignite and the star lights up. The minimum mass for the formation of a star is about 80 times the mass of Jupiter. A star is a very large, very hot ball of gas which has hydrogen fusing into helium in the core. Stars spend the majority of their life fusing hydrogen into helium. When the hydrogen is nearly used up, the star can fuse helium into heavier elements. Throughout this process, a battle goes on in the core of the star between gravity trying to collapse the star and temperature-produced gas pressure pushing the material in the star outward. During the life of a star, there is a balance between the gas pressure pushing out and gravity pushing in. |
SciQ | SciQ-3152 | electrochemistry, redox, nomenclature, electrons
"*Negative is cathode", it says, and we are back to my question in the top: why do the electrons (black spheres) move towards the negative cathode in that schematic?
Many more diagrams agreeing with this latter one are found from a simple google search. There is no completed electronic circuit in an electrochemical cell
In an electrochemical cell, the anode is the source of electrons to the external circuit and the cathode is the sink. The circuit of charge transport gets completed by ions traveling inside the cell. A solar cell is different from an electrochemical cell in that their is no net chemical reaction. In the solar cell, electrons flow in a closed circuit - round and round in the external circuit and through the device.
Designation of anode and cathode
So labeling the anode and the cathode relies on an analogy between a voltaic cell and a photovoltaic cell as a source of electrical work. It makes sense to use the direction of electron flow in the external circuit to define anode and cathode (electrons flow from anode to cathode in the external circuit). In the voltaic cell, there is no electron flow inside the cell (there is ion flow instead to balance charges). In the photovoltaic cell, electrons flow from junction to anode and holes flow from junction to cathode (or you could say electrons flow from cathode to junction).
Unfortunately, anode and cathode are named using different conventions depending on the type of device, see this overview (and beware that the current I sometimes goes in the same direction as the electrons and sometimes not, again depending on conventions).
Negative and positive electrode
The (+) and (-) designation is confusing even just for electrochemical cells. While the designation of anode and cathode is consistent for voltaic and electrolytic cells (i.e. using and charging a battery), the designation of (+) and (-) switches, so it is uncoupled from the direction the electrons flow through the external wire.
Direction of electron flow
The following is multiple choice question (with options) to answer.
What type of cell has negative anode is positive cathode? | [
"voltaic cell",
"planetoid cell",
"picric cell",
"non-voltaic cell"
] | A | The standard cell potential is negative, indicating a nonspontaneous reaction. The battery must be capable of delivering at least 1.10 V of direct current in order for the reaction to occur. Another difference between a voltaic cell and an electrolytic cell is the signs of the electrodes. In a voltaic cell, the anode is negative and the cathode is positive. In an electrolytic cell, the anode is positive because it is connected to the positive terminal of the battery. The cathode is therefore negative. Electrons still flow through the cell form the anode to the cathode. |
SciQ | SciQ-3153 | 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.
Which human body system controls the amount of water in the body and removes wastes? | [
"mucous system",
"urinary system",
"digestive system",
"lymphatic system"
] | B | The urinary system controls the amount of water in the body and removes wastes. Any problem with the urinary system can also affect many other body systems. |
SciQ | SciQ-3154 | rocks, remote-sensing, archaeology, ground-truth
Together, #1, #2, and #3 tell us that it's probably early summer just after the river ice has broken up.
The tooth-like features in the left image are simply erosional remnants sticking out of the riverbank. They could be bedrock (not likely), ice wedges, unmelted permafrost, or simply dirt. They are on the outside of a meander, so the river is actively cutting into them, and so the river-facing faces are quite sheer and high compared to the slopes in between. The right side might be white because the conditions there had left the snow unmelted when the image was taken. And of course their shadows are longer because the river channel is at the bottom of the bluff.
If you use Google Maps or Earth to go downriver a bit (up and to the left), you will see similar features sticking out of the riverbank, but because they're at a different angle from the features in your image, the fact that they're natural is more readily apparent.
Although the terrain is much less regular on the right side of the image, again the long shadows tell the tale. There are some round lumps that may be pingoes. The shadow that looks like a man is just a coincidental jumble of shadows from the broken terrain. If you look closely at the lump that is supposed to be the "man" (which would technically be an inunnguaq) does not have any protrusions that correspond to the "arms". The "arms" are the shadow of a little cliff or shelf past the lump, which is overlapped by the lump's larger shadow.
It's similar in effect to the infamous misinterpretation of a Viking orbiter image of a natural feature on Mars as a "Face on Mars".
This is a good example of the complications of image interpretation, specifically, understanding the conditions under which the image was taken. It's also a good time to emphasize the importance of doing ground truth when interpreting images. So when you go there, let us know what you find.
The following is multiple choice question (with options) to answer.
Rounded grains indicate that the minerals eroded from what? | [
"recent rock",
"iron",
"earlier rock",
"fossils"
] | C | Cratonic rocks contain rounded sedimentary grains. Rounded grains indicate that the minerals eroded from an earlier rock. It also means that rivers or seas existed. |
SciQ | SciQ-3155 | physical-chemistry, thermodynamics, equilibrium
I know that Gibbs free energy change represents the amount of the non-expansionary work that a reaction is capable...
It is not exactly true, it is not a requirement that the process involve a reaction.
In the ligh of getafix commentary:
Take in mind that physical significance most times, in the core, is just an inaccurate idea about a physical theory/model/law. Although it may be useful sometimes from a practical perspective (and many times leads to catastrophic conclusions), it has not an add value. There is the nature. There are good formal descriptions of it obtained through years of hard work from experienced people. There are pictorial interpretations of those formal descriptions used when formalism turns too hard/complex (physical significance). I noticed that it is fashion to say that one get the true understanding of phenomena when one get the physical significance. I think that one truly understand the phenomena when feels natural the formal description and is also aware that it is just a description.
The following is multiple choice question (with options) to answer.
Changes of state of matter do not involve what type of reaction? | [
"chemical reaction",
"radiation",
"gaseous reaction",
"mechanical reaction"
] | A | Not all changes in matter involve chemical reactions. For example, there are no chemical reactions involved in changes of state. When liquid water freezes or evaporates, it is still water. No bonds are broken and no new products are formed. |
SciQ | SciQ-3156 | geology, mineralogy
There is an adage amongst some geologists that states "gold is where you find it". There is no altitude preferable for finding gold deposits. It's found in mountains, in deserts, in forests, under salt lakes, even dissolved in the oceans. The oceans contain the largest quantities of gold, but it is uneconomic to extract it from sea water because the concentration are so low.
Biological indicators, such a vegetation may work for some base metals, such as copper, but not necessarily for gold.
Also, gold can occur as a deposit of just gold, but it can also occur in association with other metals in the form of polymetallic deposits which contain gold, silver, copper, lead or zinc, even uranium.
Finally, not all deposits of minerals, gold included, are reserves. To be classified as a reserve and an orebody, a deposit of mineralization must be economic to mine.
The following is multiple choice question (with options) to answer.
What type of mining is used to recover ores that are deeper into earth’s surface? | [
"underwater mining",
"deep mining",
"underground",
"explosive mining"
] | C | Underground mining is used to recover ores that are deeper into Earth’s surface. Miners blast and tunnel into rock to gain access to the ores. An underground ore deposit can be approached from above, below, or sideways. The direction depends on the placement of the ore body, its depth, the concentration of ore, and the strength of the surrounding rock. An example of an underground mine can be seen below ( Figure below ). |
SciQ | SciQ-3157 | botany, species-identification, mycology
Title: What are those huge plants / fungi on trees called? I've seen them in Scotland in August 2015:
The plants / fungi were quite high (over 2m) on the tree. They are almost circular if you view them from the top, I guess (except for the part where they are connected to the tree). I guess the diameter of them might be over 14cm.
What are they called? Well I will agree with fileunderwater, it is a Fomes fomentarious. For more info check this: Fomes fomentarius is a tough perennial polypore that usually becomes hoof-shaped with age; it is found on standing and fallen hardwoods. Its woody upper surface develops grayish zones, and its brown pore surface features tiny round pores. When sliced open (no easy task, given its toughness) it is usually composed more of vaguely layered tubes than flesh.
Along with Piptoporus betulinus, Fomes fomentarius is one of two mushrooms that the Tyrolean Iceman was carrying around 5000 years ago. He apparently used Fomes fomentarius as tinder.
Description:
Ecology: Parasitic and saprobic on the wood of hardwoods (especially birches and beech); causing a white rot; growing alone or gregariously; perennial; fairly widely distributed in northern and north-temperate North America
Cap: Up to about 20 cm across; shell-shaped to hoof-shaped; with a dull, woody upper surface that is zoned with gray and brownish gray.
Pore Surface: Brownish; 2-5 round pores per mm; tube layers indistinct, brown, becoming stuffed with whitish material.
Stem: Absent.
Flesh: Brownish, thin, hard.
The following is multiple choice question (with options) to answer.
What are liverworts with a flattened, ribbon-like body called? | [
"hepatic liverworts",
"kidney liverworts",
"hornworts",
"thallose liverworts"
] | D | Jason Hollinger. Liverworts with a flattened, ribbon-like body are called thallose liverworts . CC BY 2.0. |
SciQ | SciQ-3158 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
What is made up of organisms of the same species that live in the same area? | [
"countries",
"system",
"population",
"tissue"
] | C | Communities consist of populations of different species. The size and growth of populations in a community are influenced by species interactions. For example, predator-prey relationships control the growth of both predator and prey populations. |
SciQ | SciQ-3159 | bond, electrons, lewis-structure, valence-bond-theory
Let's next examine the situation in $\ce{O2}$. Here is the molecular orbital diagram for $\ce{O2}$. As we again fill the orbitals with electrons according to the Aufbau Principle we again arrive at the point where we have two electrons remaining and the next available molecular orbital is the $\ce{\pi^{x}_{g}}$. But we see that there is a second orbital at exactly the same energy (degenerate) and it is the $\ce{\pi^{y}_{g}}$ orbital. According to Hund's Rule, rather than put both electrons into one of these orbitals, we place just one electron in each of these two degenerate orbitals. So while
$\ce{O2}$ does have two non-bonding electrons, they are not paired up - there is no lone pair, these electrons exist in separate orbitals and $\ce{O2}$ consequently has a triplet ground state resulting from these two unpaired non-bonding electrons.
So sometimes a non-bonding pair of electrons will exist as a lone pair (as in the case of water), sometimes they won't exist as a lone pair as in the case of oxygen. To solve these kinds of problems one must know (or guess) the structure of the molecule and then determine the molecular orbital arrangement. Then, when we fill these orbitals with electrons we will see if any non-bonding electrons will exist as a lone pair in a single orbital, or if the two non-bonding electrons will exist in separate orbitals and remain unpaired.
The following is multiple choice question (with options) to answer.
The oxygen atom in a water molecule pull the electrons away from the hydrogen atoms which leads to an unequal distribution of what? | [
"nitrogen",
"atomic mass",
"charge",
"orbits"
] | C | This model shows the arrangement of oxygen and hydrogen atoms in a water molecule. A water molecule has a bent or angular (non-linear) shape, with an angle of about 105°. The nucleus of the oxygen atom attracts electrons more strongly than do the hydrogen nuclei. As a result, the middle part of the molecule near oxygen has a negative charge, and the other parts of the molecule have a positive charge. In essence, the electrons are "pulled" toward the nucleus of the oxygen atom and away from the hydrogen atom nuclei. Water is a polar molecule, with an unequal distribution of charge throughout the molecule. |
SciQ | SciQ-3160 | significant-figures
Trailing zeros in a whole number with no decimal shown are not significant: Writing just "540" indicates that the trailing zero is not significant, and therefore, there are only two significant figures in this value.
Exact numbers have an infinite number of significant figures: This rule applies to numbers that are definitions. For example, $\pu{1 meter} = \pu{1.00 meters} = \pu{1.0000 meters} = \pu{1.0000000000000000000 meters}$, etc.
For a number in scientific notation: Consider a number $N \times 10^x$. All digits comprising $N$ are significant by the first 6 rules; "$10$" and "$x$" are not significant. For example, $5.02 \times 10^4$ has three significant figures: "$5.02$." "$10$" and "$4$" are not significant.
Rule 8 provides the opportunity to change the number of significant figures in a value by manipulating its form. For example, let's try writing 1100 with three significant figures. By rule 6, 1100 has two significant figures; its two trailing zeros are not significant. If we add a decimal to the end, we have 1100., with four significant figures (by rule 5). But by writing it in scientific notation: $1.10 \times 10^3$, we create a three-significant-figure value.
By rule 7, $100$ in your answer is exact number, hence carries infinite significant figures. Thus, your answer should have been $0.24$, with two significant figures (I assume you are familiar with rounding rules).
Now, let's apply Rule 8 to your answer:
$$\frac{0.021}{8.925} \times 100 = \frac{0.021}{8.925} \times 10^2 = 0.0024 \times 10^2 = 2.4 \times 10^{-1}$$
This final answer is a number in scientific notation, and hence has two significant figures.
The following is multiple choice question (with options) to answer.
Are zeroes that show only where the decimal point fall significant or not significant? | [
"sometimes significant",
"not significant",
"significant",
"neither"
] | B | Zeros that show only where the decimal point falls are not significant. For example, the number 470,000 has just two significant figures (4 and 7). The zeros just show that the 4 represents hundreds of thousands and the 7 represents tens of thousands. Therefore, these zeros are not significant. |
SciQ | SciQ-3161 | astrophysics
Title: Is there any way to survive solarwinter like in Sunshine - movie? Is there any way to survive solarwinter like in Sunshine - movie?
Solar winter is where for some reason sun looses its capasity to produce radiation( heat etc.). It doesn't loose everything but some of its radiation energy( say 50 %) That causes earth to cool down causing next "ice age" Food could be grown using UV lights, powered by nuclear fission.
We could probably do it.
But it would be the spece equivalent of a human being on a life support machine - all our time and energy would be consumed just with survival, so while humans as a species might survive, our society, culture and science would probably slow down to a crawl, or disappear completely. Most other species would die off, so it would be a pretty dismal future.
The following is multiple choice question (with options) to answer.
Torpor, a process that leads to a decrease in activity and metabolism and allows animals to survive adverse conditions, includes what long winter 'sleep'? | [
"relaxation",
"pollination",
"fermentation",
"hibernation"
] | D | Energy Requirements Related to Levels of Activity The more active an animal is, the more energy is needed to maintain that activity, and the higher its BMR or SMR. The average daily rate of energy consumption is about two to four times an animal’s BMR or SMR. Humans are more sedentary than most animals and have an average daily rate of only 1.5 times the BMR. The diet of an endothermic animal is determined by its BMR. For example: the type of grasses, leaves, or shrubs that an herbivore eats affects the number of calories that it takes in. The relative caloric content of herbivore foods, in descending order, is tall grasses > legumes > short grasses > forbs (any broad-leaved plant, not a grass) > subshrubs > annuals/biennials. Energy Requirements Related to Environment Animals adapt to extremes of temperature or food availability through torpor. Torpor is a process that leads to a decrease in activity and metabolism and allows animals to survive adverse conditions. Torpor can be used by animals for long periods, such as entering a state of hibernation during the winter months, in which case it enables them to maintain a reduced body temperature. During hibernation, ground squirrels can achieve an abdominal temperature of 0° C (32° F), while a bear’s internal temperature is maintained higher at about 37° C (99° F). If torpor occurs during the summer months with high temperatures and little water, it is called estivation. Some desert animals use this to survive the harshest months of the year. Torpor can occur on a daily basis; this is seen in bats and hummingbirds. While endothermy is limited in smaller animals by surface to volume ratio, some organisms can be smaller and still be endotherms because they employ daily torpor during the part of the day that is coldest. This allows them to conserve energy during the colder parts of the day, when they consume more energy to maintain their body temperature. |
SciQ | SciQ-3162 | genetics, chromosome, speciation
different species in the same location normally have different chromosomal numbers;
on the macrogeographical level at least some species show certain gradients in chromosomal numbers;
sometimes the same variation can be observed on the level of local populations.
Hybrids between species are viable and not sterile, but rare in nature. Fecundity of hybrids is lower than that of the parental species, and this seems to serve as an additional post-zygotic mechanism of species isolation.
Crossings between specimens of the same species with different numbers of chromosomes do occur in mixed populations and are also possible for parents coming from different extremities of the above mentioned chromosomal cline. In the case of mixed populations frequency of these hetezygotes is less than expected by Hardy-Weinberg. Such offspring is fertile, and its lowered frequency is associated with higher incidence of abnormal meiosis.
On the cytological level (normal) meiosis in a heterozygote individual is remarkable in showing trivalents instead of bivalents for the polymorphic chromosomes:
(a metaphase with a trivalent in the center and two bivalents) (from Staiger & Bocquet 1956)
In addition, in four out of five species of the complex chromosomal sex determination is of the following uncommon type: males are homogametic with sex chromosomes ZZ, while females are heterogametic with ZW1W2 chromosomes. So, females normally have in total an odd number of chromosomes and in their meiosis one observes a trivalent similar to the one shown above: the metacentric Z-chromosome conjugates with the two acrocentrix W-chromosomes.
Some references available on-line:
Lécher & Prunus 1971 (in French)
Solignac 1981 (English, on isolating mechanisms in general)
Lécher et al 1995 (a review in English)
Kappas et al 2013 (a review in English - see pages 23-26)
These are highly relevant to the question, but not accessible on the web:
The following is multiple choice question (with options) to answer.
What produces gametes with different alleles? | [
"prokaryotes",
"heterozygotes",
"anthocyanins",
"chromatids"
] | B | |
SciQ | SciQ-3163 | evolution, terminology, phylogenetics
Title: Is there a name for this phenomenon described in "Phylogenies and the Comparative Method"? The figures below are from Felsenstein's paper "Phylogenies and the Comparative Method". I was wondering if there was a specific name for this effect where there is an apparant correlation that is actually the result of the data being structured into two separate groups, where there is no correlation within groups but an apparent correlation between groups. "Phylogenetic non-independence" doesn't seem specific enough. I've seen this termed "phylogenetic pseudoreplication", but I can't remember offhand where. I'll see if I can find it. Without a tree, the boxes and Xs essentially represent 2 data points. As Remi.b suggests, this is really just high phylogenetic signal.
The following is multiple choice question (with options) to answer.
What term is used to describe structures that are similar in unrelated organisms? | [
"symbolic",
"reproductive",
"analogous",
"isolated"
] | C | Analogous structures are structures that are similar in unrelated organisms. The structures are similar because they evolved to do the same job, not because they were inherited from a common ancestor. For example, the wings of bats and birds, shown in Figure below , look similar on the outside. They also have the same function. However, wings evolved independently in the two groups of animals. This is apparent when you compare the pattern of bones inside the wings. |
SciQ | SciQ-3164 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
What is defined as a saturated layer of rock or soil? | [
"aquifer",
"artesian well",
"culvert",
"river bank"
] | A | An aquifer is a saturated layer of rock or soil. |
SciQ | SciQ-3165 | breathing
Title: Why does the pulmonary artery have higher glucose concentration than the pulmonary vein? If the pulmonary artery have higher glucose concentration than the pulmonary vein, does it mean glucose will be consumed during gas exchange?
That confused me because gas exchange is something like diffusion and shouldn't consume any glucose Gas exchange doesn't but the cells of the tissue it occurs in do consume glucose, even the cells in the walls of the artery will consume some. The cells in the lungs still need to be fed and only one of those two vessels has flow going into the tissue so it is the one that has to carry that glucose into the tissue.
The following is multiple choice question (with options) to answer.
Air flows into the lungs largely due to a difference in what? | [
"pressure",
"resistance",
"thrust",
"gravity"
] | A | Pulmonary Ventilation The difference in pressures drives pulmonary ventilation because air flows down a pressure gradient, that is, air flows from an area of higher pressure to an area of lower pressure. Air flows into the lungs largely due to a difference in pressure; atmospheric pressure is greater than intra-alveolar pressure, and intra-alveolar pressure is greater than intrapleural pressure. Air flows out of the lungs during expiration based on the same principle; pressure within the lungs becomes greater than the atmospheric pressure. Pulmonary ventilation comprises two major steps: inspiration and expiration. Inspiration is the process that causes air to enter the lungs, and expiration is the process that causes air to leave the lungs (Figure 22.17). A respiratory cycle is one sequence of inspiration and expiration. In general, two muscle groups are used during normal inspiration: the diaphragm and the external intercostal muscles. Additional muscles can be used if a bigger breath is required. When the diaphragm contracts, it moves inferiorly toward the abdominal cavity, creating a larger thoracic cavity and more space for the lungs. Contraction of the external intercostal muscles moves the ribs upward and outward, causing the rib cage to expand, which increases the volume of the thoracic cavity. Due to the adhesive force of the pleural fluid, the expansion of the thoracic cavity forces the lungs to stretch and expand as well. This increase in volume leads to a decrease in intra-alveolar pressure, creating a pressure lower than atmospheric pressure. As a result, a pressure gradient is created that drives air into the lungs. |
SciQ | SciQ-3166 | 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.
The cytoplasm divides during what stage of the cell cycle? | [
"electrolysis",
"birthing",
"cytokinesis",
"capitis"
] | C | 3. The third step is the division of the rest of the cell. This is called cytokinesis, as it is in a prokaryotic cell. During this step, the cytoplasm divides, and two daughter cells form. |
SciQ | SciQ-3167 | evolution, speciation
Lastly, I consider whether primary and secondary sympatric speciation represent a mechanistic dichotomy, I suggest that primary and secondary contact can leave a similar genomic signature, when speciation is driven by tightly clustered or large effect loci. Arguably, the advent of affordable population genomic studies should place less focus on whether study systems result from primary or secondary contact and instead focus on the mechanistic aspects of the genomic architecture and making progress in identifying the conditions and processes under which natural and sexual selection can drive speciation, without extrinsic barriers to gene flow. TLDR
Sympatric speciation and allopatric speciation with later migration into the same habitat were historically diffucult to distinguish without looking at palaeo-biological data. The paper argues that while palaeo-genetics has made this easier, it is still difficult to distinguish pure sympatric speciation (which it calls primary) and sympatric speciation with a geneflow from an geographically separated (allopatrically speciated?) subpopulation (which it terms "secondary sympatric speciation" or "speciation with secondary gene flow", "...with secondary contact" etc.).
Speciation
Speciation is the divergence of one species (with one gene pool) into two different species (with different gene pools). It is obvious that this will happen if subpolulations are geographically separated and continue to adapt to their local conditions (allopatric speciation).
However, Mayr suggested (back in the 1940s) that there is another type of speciation that happens while the speciating populations share a habitat, and, consequently, while gene flow between these subpopulations is maintained until the speciation process is complete. This requires strong selection pressure towards two different ecological niches each with their associated adaptations.
Empirical examples have been discussed and called into question again. One cool and frequently discussed example is that of the apple maggot in North America that has developed from the hawthorn maggot after the introduction of apples in North America.
Debate
The following is multiple choice question (with options) to answer.
Researchers have also used insect courtship to explore genetic variation underlying differences in what? | [
"behavior",
"reproduction",
"function",
"instance"
] | A | |
SciQ | SciQ-3168 | neuroscience, brain
Title: What is in the space between neurons in a brain? When neuron animations are displayed, there are frequently seen neurons, axons arranged in a lattice with a lot of empty space between. I'm interested if there is indeed empty space in the brain, or if it is filled with some sort of fluid? I've checked an article on cerebrospinal fluid but am not sure that it is present all throughout the brain.
The reason I'm asking is that I'm thinking of neurotransmitters- they are released in synapses, but I'm not sure how they stay there - are they suspended in some liquid as well? Not so empty, actually.
The human brain has a mass of ~1.5kg, and volume ~1200cc (a little bigger for men, a little smaller for women). So is heavier than water by a good margin.
While it has Cerebrospinal fluid, that only occupies the subarachnoid space (the space below the skull and above the cortex, contained between two layers: pia matter and arachnoid membrane) and the ventricular system (several spaces inside the brain, remnants of the embryological development of the brain).
Neuron density may vary widely, depending mainly on the particular characteristics of neuron cell types and their interconnections. But besides neurons, there's a lot of infrastructure inside the brain. For example:
Astroglia: They are a type of glial cells which participate in the formation of the blood-brain barrier (supporting the endothelial cells), nourishing of neurons, maintenance of ion and neurotransmitter concentrations, among others. They also keep in place most of the tissue.
Microglia: Small cells with immune (phagocitic) functions inside the brain.
Radial glia: A more specialized precursor cell, that also participates in neuronal migration in the brain.
Oligodendrocites: Cells responsible for the insulation (myelination) of axons.
Neuroepithelial cells: The stem cells in the brain.
The following is multiple choice question (with options) to answer.
What part of the brain lies under the cerebrum and behind the brain stem? | [
"spinal cord",
"thymus",
"cerebellum",
"medulla"
] | C | The cerebellum is the next largest part of the brain. It lies under the cerebrum and behind the brain stem. The cerebellum controls body position, coordination, and balance. Whether you are riding a bicycle or writing with a pen, you are using your cerebellum. |
SciQ | SciQ-3169 | molecular-biology, molecular-genetics, development, sex
Quote from a Review (Yao 2005):
We have just begun to glimpse into the mechanisms underlying ovarian development. Convincing evidence challenges us to reconsider the existing paradigm that describes ovarian development as a default system. The default concept was first proposed in the early 1950s when Jost performed the groundbreaking experiments to demonstrate mechanisms of sex differentiation of reproductive tracts (Jost, 1947, 1953, 1970). The term “default” was not originally intended to describe the developmental status of the ovary. Instead, it is referred to the female reproductive tract or the Mullerian duct based on the fact that the female reproductive tract forms in both XX and XY individuals in the absence of gonads. Indeed, now it has become evident that early ovarian development is an active process involving intrinsic cell fate decisions and complex crosstalks between germ cells and somatic cells. Most intriguingly, the appearance of testicular structures in XX individuals where Sry and its downstream components are absent further raises the improbable question: Could the testicular development be default after all?
The following is multiple choice question (with options) to answer.
In human females, the mammary glands are associated with, but not part of, what organ system that is used to create new humans? | [
"endocrine",
"digestive",
"reproductive",
"immune"
] | C | |
SciQ | SciQ-3170 | volcanoes, pyroclastic-flows
Edit: In a research* it is suggested that a turbidite current can flow over barriers, if the thickness of the flow exceeds %65 of the barrier. One may interpret this that, after a pyroclastic current dives to shallow water it may come back to the surface again.
The following is multiple choice question (with options) to answer.
What is the term for volcanic mudflows? | [
"rivers",
"plumes",
"lahars",
"cones"
] | C | Mudflows or lahars, which are volcanic mudflows, are mass movements that contain a lot of water. |
SciQ | SciQ-3171 | observational-astronomy, history
Title: Nicolas Copernicus discovery As I was reading about the heliocentric model, a question came up: How was Nicolaus Copernicus able to figure out that the sun is at the center of the solar system, and that all planets orbit around it, even though the telescope had not been invented yet? During his time the geocentric model was the standard. Copernicus did not figure out that the Sun was at the centre of the solar system. He merely proposed that a heliocentric model simplified the calculation of planetary orbits. Epicycles (circles within circles) were still needed in the Copernican model, for instance for the orbit of Mars, but there were fewer of them than in the Ptolemaic model.
The Copernican model received a boost when Kepler, discovering that planetary orbits were elliptical, removed the need for epicycles completely, thus increasing Copernicus' advantage over Ptolemy.
The first evidence that the Copernican model was a true representation of actual reality came with the observation of stellar parallax in 1806. Until then, it was preferred only because it was a simpler description - a much simpler one, after Kepler.
The following is multiple choice question (with options) to answer.
During the scientific revolution, who proposed that the sun, not earth, is the center of the solar system? | [
"Galileo",
"janus",
"copernicus",
"Newton"
] | C | The Scientific Revolution occurred in Europe. This was the beginning of modern Western science. Many scientific advances were made during this time. Copernicus proposed that the sun, not Earth, is the center of the solar system. |
SciQ | SciQ-3172 | string-theory, quantum-chromodynamics, confinement
Title: Can we quantitatively understand quark and gluon confinement in quantum chromodynamics and the existence of a mass gap? Quantum chromodynamics, or QCD, is the theory describing the strong nuclear force. Carried by gluons, it binds quarks into particles like protons and neutrons. According to the theory, the tiny subparticles are permanently confined. A quark or a gluon cannot be taken from a proton because the strong force gets stronger with distance. How much do we understand of this phenomenon? and what do we hope to find about it by studying M-theory? Confinement cannot be rigorously shown in QCD with current techniques, because all analytic results in QCD are perturbative and the perturbative expansion breaks down at low energies where the coupling becomes strong.
QCD has a negative $\beta$-function, i.e. the Yang-Mills coupling grows at lower energies and becomes weaker at high energies. But the $\beta$-function itself is only known perturbatively, that is as a power series in the coupling strength. This expansion makes sense when the coupling is weak not when it is strong. This perturbative calculation of the $\beta$-function therefore teaches us two lessons:
The theory is asymptotically free, the coupling becomes weaker and weaker at high energies. Since the perturbative computation is justified in this regime, we can conclude that asymptotic freedom has been shown rigorously.
At low energies the coupling becomes strong due to the $\beta$-function, but the calculation of the $\beta$-function itself relies on weak coupling. So we cannot say anything definite about this regime. However, the growing coupling is seen as a hint of confinement. One cannot, for example, compute meson masses in perturbative QCD.
The following is multiple choice question (with options) to answer.
Quantum chromodynamics combines what property with quark theory? | [
"mass",
"sound",
"contrast",
"color"
] | D | Why must hadrons be white? The color scheme is intentionally devised to explain why baryons have three quarks and mesons have a quark and an antiquark. Quark color is thought to be similar to charge, but with more values. An ion, by analogy, exerts much stronger forces than a neutral molecule. When the color of a combination of quarks is white, it is like a neutral atom. The forces a white particle exerts are like the polarization forces in molecules, but in hadrons these leftovers are the strong nuclear force. When a combination of quarks has color other than white, it exerts extremely large forces—even larger than the strong force—and perhaps cannot be stable or permanently separated. This is part of the theory of quark confinement, which explains how quarks can exist and yet never be isolated or directly observed. Finally, an extra quantum number with three values (like those we assign to color) is necessary for quarks to obey the Pauli exclusion principle. Particles such as the Ω − , which is ++ composed of three strange quarks, sss , and the Δ , which is three up quarks, uuu, can exist because the quarks have different colors and do not have the same quantum numbers. Color is consistent with all observations and is now widely accepted. Quark theory including color is called quantum chromodynamics (QCD), also named by Gell-Mann. |
SciQ | SciQ-3173 | genetics
Title: What distinguishes Mendelian Inheritance from Non-Mendelian Inheritance? I'm having some trouble determining what exactly is the difference between Mendelian inheritance and non-Mendelian inheritance. For instance, I understand that chromosomal abnormalities such as Down's Syndrome fall under non-Mendelian inheritance because they concern chromosomes, not single genes. And I also understand that Mendelian inheritance concerns single genes, as in Sickle-cell anemia (which is an autosomal recessive disorder).
What confuses me is the fact that our textbook discusses dihybrid and trihybrid (concerning 2 genes and 3 genes, respectively) crosses under the Mendelian inheritance chapter, when to me it seems like these crosses are non-Mendelian because they deal with multiple genes. However, Gregor Mendel did in fact use the dihybrid cross to deduce the law of independent assortment, so I'm completely confused. Could someone please clarify this for me? I'm afraid that I'm maybe misinterpreting something. You can discuss multiple genes within the framework of Mendelian inheritance; what you're probably thinking of, though, is the fact that Mendelian inheritance doesn't recognize the idea of multiple genes that contribute to a single trait.
For example, if there is a gene that controls petal color (blue vs. white, with blue = dominant) and a gene that controls height (short vs. tall, with tall = dominant), then Mendelian inheritance predicts that two short plants with white flowers will only produce short plants with white flowers.
But if there are multiple genes that interact to determine height in a complex way, that's outside the scope of Mendelian inheritance.
The following is multiple choice question (with options) to answer.
Traits inherited in mendelian patterns are either? | [
"divergent or dominant",
"dominant or recessive",
"dominant or autosomal",
"recessive or allelic"
] | B | |
SciQ | SciQ-3174 | genetics
Additional response added as requested:
I see what you are getting at - why do children seem like such individual and unique things sometimes?
In sexual reproduction, the offspring are the product of the shuffling of the parent's genomes through meiosis, where the pairs of chromosomes we have are combined to make a single chromosome that will be half of the children genome.
This process can result in completely novel combinations of genes while conveying many likenesses from the parent. I would guesstimate that this is the major cause of the uniqueness of offspring/children.
Also in mammals there are some cell lines which splice families of genes which will cause offspring to be potentially quite different from either parent. Immune genes for instance are created from scratch from a bunch of genes that the parents give. Making each offspring unique but also the product of the parent's genetic repertoire. This can be significant as it affects health and also to some extent attraction - studies have shown that people who smell attractive to us are immunologically distinct from us.
@David mentions epigenetic variation, which is a more recent significant development. During our life, the germline (sperm/egg) DNA may be chemically labelled depending upon environmental conditions we experience. A famous example is experiencing famine conditions, which caused the children to be born on the small side amongst other effects. More recent studies have shown that this is a widespread mechanism to control cells in our body during our lifetime as well as communicate to our offspring how life is. It is expected that this labeling does not affect us forever - the epigenetic labels change over the course of a generation quite often (we believe).
The following is multiple choice question (with options) to answer.
What kind of reproduction results in offspring that are genetically unique? | [
"fragmentation",
"asexual reproduction",
"budding",
"sexual reproduction"
] | D | Sexual reproduction results in infinite possibilities of genetic variation. In other words, sexual reproduction results in offspring that are genetically unique. They differ from both parents and also from each other. This occurs for a number of reasons. |
SciQ | SciQ-3175 | 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.
How many vertebrae make up the human vertebral column? | [
"32",
"33",
"35",
"35"
] | B | Human Vertebral Column and Vertebrae. The human vertebral column consists of 33 vertebrae. Two vertebrae are shown here enlarged. |
SciQ | SciQ-3176 | human-biology, cell-biology
Title: What kinds of cells does human saliva contain? I have heard that our saliva contains cells. What cell types can be found in human saliva? It contains white blood cells (leukocytes) and cells from the inner lining of the mouth (buccal epithelial cells). The DNA obtained from these cells is the basis of DNA profiling based on saliva samples.
Source: Salimetrics
The following is multiple choice question (with options) to answer.
What do cells of dermal tissue secrete? | [
"moisture",
"blood",
"hair",
"cuticle"
] | D | Dermal tissue covers the outside of a plant. It's like the plant's skin. Cells of dermal tissue secrete a waxy substance called cuticle. Cuticle helps prevent water loss and damage to the plant. |
SciQ | SciQ-3177 | evolution, taxonomy
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild.
That last part takes care of the ligers and tiglons. But what if we consider plants? Under the definition I just gave, most grasses (around 11,000 species) would have to be considered as one species. In the wild, most grasses will freely pollinate related species and produce hybrid seed, which germinates. You might then think we could just modify the definition to specify that the offspring must be fertile (i.e. able to reproduce with one another)...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but do not breed freely with members of another species in the wild to produce fertile progeny.
Unfortunately, the situation is still more complicated (we've barely started!). Often wild hybridisation events between plants lead to healthy, fertile offspring. In fact common wheat (Triticum aestivum) is a natural hybrid between three related species of grass. The offspring are able to breed freely with one another.
Perhaps we could account for this by taking into account whether the populations usually interbreed, and whether they form distinct populations...
The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of populations or meta-populations of related individuals that resemble one another, are able to breed among themselves, but do tend not to breed freely with members of another species in the wild to produce fertile progeny.
The following is multiple choice question (with options) to answer.
What is the term for many different types of animals within the same species? | [
"habitat",
"pollution",
"differentiation",
"diversity"
] | D | |
SciQ | SciQ-3178 | organic-chemistry, inorganic-chemistry, acid-base, solvents, molecules
Title: How can one find products when one knows the reagents? I'm going to use an example (I could have used a different one);
On the document it is about the study of the chemical balance of an acid-basic solution.
The chemists have written the chemical reaction equation to make a table of the evolution of pH during the reaction.
If I understand with this equation I'll be able to understand others.
$\ce{CH3COOH + H2O ->CH3COO- + H3O+}$
Here is what I already understand:
This is the equation of methanoic acid with water
I understood why the general formula of methanoic acid is $\ce{CH3COOH}$
What I want to know is how do we know that
$\ce{CH3COOH}$ changes into $\ce{CH3COO-}$ ?
$\ce{H2O}$ changes into $\ce{H3O+}$?
The following is multiple choice question (with options) to answer.
What is a process in which some substances change into different substances? | [
"a toxic reaction",
"a chemical reaction",
"a thermodynamic reaction",
"a bio reaction"
] | B | A chemical reaction is a process in which some substances change into different substances. In a chemical reaction, bonds break in reactants and new bonds form in products. |
SciQ | SciQ-3179 | bacteriology, soil, nitrogen-cycle
While nitrite is the main product, the enzyme from N. europaea can produce nitric oxide as well. Therefore Step 2 can produce nitric oxide (NO). In this case, additional mechanisms of converting NO to NO2 are involved.
Further destiny of released nitrite can be different. In one process it could be oxidized by different microorganisms (bacteria, archaea) to nitrate (NO3) which could be consumed by plants or washed out to deeper horizons with water. In another case, nitrite, nitric oxide and nitrate could be involved in process of denitrification. During this process, a group of denitrifying organisms (bacteria, archaea and fungi) consume nitrogenous compounds and reduce them to nitrogen (N2), which can escape to the atmosphere. This process can occur through different metabolic pathways mainly with aid of reductases like nitric oxide reductase. One of the possible intermediate product of such pathways is a nitrous oxide (NO2). If N2O escapes from cells we can observe a resale of nitrous oxide from soil.
Let's return to your first question, and particularly to the part where you ask about significant amounts of nitrous oxide.
First of all, nitrification is a natural process and is a part of the nitrogen cycle. Some organisms fixate nitrogen and convert it to ammonia, some oxidize ammonia to nitrous compounds and some of them reduce it back to nitrogen. It occurs everywhere virtually in all terrestrial and water biocenoses. In a healthy ecosystem, the inflow of nitrogen is theoretically equal to the outflow (with temporal deposition in trophic chains). In such natural conditions, the release of nitrous oxide should be neglectable.
The situation changes significantly when we add an ammonia to soil artificially as a fertilizer. The main problem is that we break an equilibrium between nitrogen fixation, nitrification and denitrification. The second big problem is that an ammonia is toxic for most organisms, so we can alter microbiome. In such case, we can expect an excess of products of nitrification and improper denitrification with exaggerated levels of released nitrous oxide. The actual proportions vary significantly depending on both biotic and abiotic conditions, therefore it is difficult to predict real levels of nitrous oxide released without in situ examination.
The following is multiple choice question (with options) to answer.
What causes nitrate to go back to its gaseous nitrogen state? | [
"denitrifying bacteria",
"phytoflagellate bacteria",
"enzymes",
"decomposers"
] | A | Denitrifying bacteria turn nitrate back into gaseous nitrogen. |
SciQ | SciQ-3180 | biochemistry, metabolism, bioenergetics
Title: What is the energy source for adipocytes? Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes? Adipocytes use glucose as an energy source. They express the insulin-responsive glucose transporter GLUT4 just like muscle cells so that when blood glucose levels rise they are primed to take the glucose up for fatty acid biosynthesis, but they also use glucose as a fuel molecule.
The following is multiple choice question (with options) to answer.
What is the metabolic process by which cells obtain energy by “burning” glucose? | [
"cellular transportation",
"electromagnetic respiration",
"cellular digestion",
"cellular respiration"
] | D | The use of the word respiration in relation to gas exchange is different from its use in the term cellular respiration . Recall that cellular respiration is the metabolic process by which cells obtain energy by “burning” glucose. Cellular respiration uses oxygen and releases carbon dioxide. Respiration by the respiratory system supplies the oxygen and takes away the carbon dioxide. |
SciQ | SciQ-3181 | quantum-mechanics, visible-light, reflection, optical-materials
Can someone explain me the interaction between the photon and the molecules in case of a reflection on a solid surface with white color?
I am not asking about direction of light, not asking how the photon knows where to go. (This is well explained already by Feynman's QED.) I realized that I got a downvote, which normally means the answer is wrong, while I think it is true. But the OP has updated the question, so I take this as a chance to also update my answer.
Udate
It seems you expect one simply answer why different things in nature appear white, but the truth is there are different reasons for different things.
For example, clouds are white because of Mie scattering, that is scattering of photons on particles (here small water droplets). There is almost no wavelength-dependence of the scattering efficiency in the visible range, so that all wavelengths in the incoming sunlight are scattered with the same probability, and as a result the cloud is white. But notice, the incoming light has to contain all wavelengths for that. During sunset for example, the cloud base is sometimes red because illuminated by the sun, which is red when close to the horizon during sunset (the reason is that blue light is scattered out of the direct beam due to Rayleigh scattering that prefers to scatter blue light and is responsible for the blue sky during the day).
Another white material is milk, which is a liquid. It is also white because of scattering, this time on particles within the milk. But again, you need an illumination of a light source containing all wavelengths to get a white substance. In a green room, a glass if milk will appear greenish of course...
The following is multiple choice question (with options) to answer.
What weakly scatters visible light? | [
"air",
"Reflection",
"water",
"space"
] | A | The color of a material is due to the ability of its atoms to absorb certain wavelengths while reflecting or reemitting others. A simple red material, for example a tomato, absorbs all visible wavelengths except red. This is because the atoms of its hydrocarbon pigment (lycopene) have levels separated by a variety of energies corresponding to all visible photon energies except red. Air is another interesting example. It is transparent to visible light, because there are few energy levels that visible photons can excite in air molecules and atoms. Visible light, thus, cannot be absorbed. Furthermore, visible light is only weakly scattered by air, because visible wavelengths are so much greater than the sizes of the air molecules and atoms. Light must pass through kilometers of air to scatter enough to cause red sunsets and blue skies. |
SciQ | SciQ-3182 | ## 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.
Arteries carry oxygenated blood away from the heart, what carries un-oxygenated blood back to the heart? | [
"glands",
"veins",
"intestines",
"lungs"
] | B | |
SciQ | SciQ-3183 | rna-seq, r, deseq2, networks
Title: What are the ways to process a list of differentially expressed genes? We are studying six different human macrophage/dendritic cell types isolated from healthy skin. They all differ from each other in a few cell surface markers.
We are interested in the characteristics of each cell type ("marker" genes or biological processes), the differences between them (especially cell surface proteins), and their relations (e.g. "which are the closest relatives?") as can be inferred from the transcriptome, from an immunological point of view. The wider context is HIV-infection, thus HIV infection-related differences (and similarities) are of particular interest.
One naive approach is to contrast two of the most similar cell types (as inferred from previous knowledge, the sorting strategy and the PCA plot), and produce a list of differentially expressed (DE) genes.
I have now a list of ~500 DE genes between two cell types, together with fold changes, expression means etc., produced with DESeq2 on bulk RNA-seq data.
What are the best practices to process this list to answer some of the above?
I've found PPI analysis on NetworkAnalyst, and GO and pathway analysis on InnateDB useful.
What other options are available?
I'm particularly interested in approaches using R. You originally had asked a very broad question, so I'll try to demonstrate why that is such a hard question to answer. I've done two fairly large differential analysis studies (and a few smaller ones) covering very different areas of research, and the approaches that other researchers used subsequent to my differential expression calculations were unsurprisingly also very different.
The following is multiple choice question (with options) to answer.
What type of analysis is performed to study gene expression patterns in cells? | [
"dna analysis",
"residues analysis",
"rna analysis",
"proteins analysis"
] | C | RNA analysis is performed to study gene expression patterns in cells. RNA is naturally very unstable because RNAses are commonly present in nature and very difficult to inactivate. Similar to DNA, RNA extraction involves the use of various buffers and enzymes to inactivate macromolecules and preserve the RNA. Gel Electrophoresis Because nucleic acids are negatively charged ions at neutral or basic pH in an aqueous environment, they can be mobilized by an electric field. Gel electrophoresis is a technique used to separate molecules on the basis of size, using this charge. The nucleic acids can be separated as whole chromosomes or fragments. The nucleic acids are loaded into a slot near the negative electrode of a semisolid, porous gel matrix and pulled toward the positive electrode at the opposite end of the gel. Smaller molecules move through the pores in the gel faster than larger molecules; this difference in the rate of migration separates the fragments on the basis of size. There are molecular weight standard samples that can be run alongside the molecules to provide a size comparison. Nucleic acids in a gel matrix can be observed using various fluorescent or colored dyes. Distinct nucleic acid fragments appear as bands at specific distances from the top of the gel (the negative electrode end) on the basis of their size (Figure 17.4). A mixture of genomic DNA fragments of varying sizes appear as a long smear, whereas uncut genomic DNA is usually too large to run through the gel and forms a single large band at the top of the gel. |
SciQ | SciQ-3184 | species-identification, entomology
Title: Can you identify this animal?
It was in the bathroom, 2cm in lenght (or so). It has two small antenas on the head. I live on Balkan peninsula, inland. That is a European Millipede.
I found this picture by searching European Millipede. Obviously there are different types - and this is the one you have.
Here is a wiki link I found: https://en.wikipedia.org/wiki/Cylindroiulus
I think your specifically is a Cylindroiulus britannicus
.
The following is multiple choice question (with options) to answer.
What class are centipedes and millipedes in? | [
"spirogyra",
"terapoda",
"xerophyte",
"myriapoda"
] | D | Myriapoda, which includes centipedes and millipedes. All of these animals live on land, and can have anywhere from ten to nearly 200 pairs of appendages. |
SciQ | SciQ-3185 | visible-light, reflection, laser, refraction
Title: Curved Light stream? I was wondering, a while ago, i asked if there is a way to bend light someway, which I got the answer is index of refraction.
Which is when light passes through a material it refracts to a certain degree.
In this question I wish to know if this method when applied with a dense enough index, that that when you turn the light beam to a different direction, do you see it arc or curve in a smooth form, that given enough index of refraction or am I thinking of something else?
I usually thought certain substances like a water tank with oil or sugar can cause a light beam to curve smoothly. Are you asking if it is possible to get a curved light beam by varying the refraction index?
Yes, it is possible. Every time light propagates in a medium with a non uniform refraction index, the ray trajectory is not rectilinear. If there is a sharp transition between regions with two different values of the refraction index, the Snell law controls the angle the refracted beam gets closer or farther from the normal to the incidence point.
If the refraction index is a smooth function of the position, the light beam is bent smoothly and follows a curve trajectory instead of a piece-wise straight line.
The phenomenon can nicely observed with a laser pointer and a transparent container (like a fish tank) where some salt (NaCl is ok) is put on the bottom and then the container is gently filled by water (without stirring or creating turbulence). After some hours (even one day) there is an almost uniform vertical gradient of salt concentration. A laser beam entering from a side wall is clearly bent as in this picture. The entrance point is the spot on the left.
The following is multiple choice question (with options) to answer.
Light moving from air into water is bent ___________ the normal? | [
"Longly",
"thinly",
"less",
"more"
] | D | Light moving from air into water is bent ___________ the normal. |
SciQ | SciQ-3186 | neuroscience
Title: Nervous system : Nerve signals If the electrical signals from all the various organs throughout the body eventually connect to the nerves in the spinal column traveling up to the brain, how does the brain differentiate the different signals. Is the nerve in the spinal column like an electrical conduit with many wires inside? Yes is the simple answer. A nerve will go up to a specific part of the brain which the brain knows corresponds to a certain region of the body. It isn't perfect though e.g. pain in the diaphragm confuses the brain which doesn't recognise that pain must be coming from there so instead tells the body there is shoulder pain, however this is useful in medicine. Another infamous example is pain from heart disease (angina) which causes pain in the jaw and arm. Perhaps even more interestingly, if a nerve is cut and then grows back linking to the wrong nerve it may lead to the completely wrong part of the body being identified when touched. Also if the brain itself is stimulated in these corresponding areas, a person will feel he or she is indeed being touched in a certain part of the body.
The following is multiple choice question (with options) to answer.
An electrical signal along a nerve cell triggers the secretion of what? | [
"attenuation molecules",
"axons",
"conduction molecules",
"neurotransmitter molecules"
] | D | |
SciQ | SciQ-3187 | bond, ions
But in October 2016, astronomers reported that the very basic chemical ingredients of life—the carbon-hydrogen molecule (CH, or methylidyne radical), the carbon-hydrogen positive ion (CH+) and the carbon ion (C+)—are the result, in large part, of ultraviolet light from stars, rather than in other ways, such as the result of turbulent events related to supernovae and young stars, as thought earlier. So we can say these ions are in existence in our universe.
I hope it helps you.
I'm new to Stackoverflow so sorry if I've made any mistake in giving your desired answer
.
The following is multiple choice question (with options) to answer.
Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur are basic elements that form what type of compounds, which are vital to life? | [
"inorganic compounds",
"amino acids",
"organic compounds",
"hydrocarbons"
] | C | In just the right combinations, you get life. Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Some of the most basic of elements, but some of the most important. Together they can form countless combinations of organic compounds. And in just the right combinations, anything can happen. |
SciQ | SciQ-3188 | organic-chemistry, molecular-structure, molecules
Title: Complex organic molecules I am studying astronomy and came across the following term in the astrochemistry course called 'complex organic molecules' or also written as COMs. My question is: What is exactly meant with these molecules? Is it just a molecule with more than one carbon atom? tl;dr: two different definitions. Astronomy: multiple carbon atoms in molecule. Chemistry: polymer
Interestingly enough, after reading about COMs here, as well as reading the Wikipedia page and the corresponding arXiv paper, it seems like chemists and astronomers have different definitions of what a complex organic molecule should be!
As far as I knew, in chemistry complex organic molecules were long polymers, such as proteins, which were composed of thousands upon thousands of amino acid units. In the astronomy paper, however, they cite other types of molecules.
$\ce{CH3OH,
CH3CHO, HCOOCH3 and CH3OCH3}$, all cited as "complex" (haha) organic molecules in the paper, would appear to chemists as relatively simple molecules. (I read the paper, because it piqued my interest that something like a protein could be found in space). I then read the Springer article.
The term “complex organic molecules” is used differently in astronomy and chemistry. In astronomy, complex organic molecules are molecules with multiple carbon atoms such as benzene and acetic acid. These molecules have been detected in interstellar space with radio telescopes. In chemistry, “complex organic molecules” refer to polymer-like molecules such as proteins.
The following is multiple choice question (with options) to answer.
Urea and carbon dioxide are molecules with how many carbon atoms? | [
"four",
"even number",
"two",
"one"
] | D | |
SciQ | SciQ-3189 | cell-biology, gene-expression, development, embryology
I'm reluctant to go into too much detail on this because you're asking about a complex process that is still under active study and I'm unclear as to how much information you actually want. A book could be written on this subject alone, and many review papers have been published. Here's a recent one:
Development: Do Mouse Embryos Play Dice?
I suggest you read that and then if you have further, more specific questions, we can try and answer them for you.
The following is multiple choice question (with options) to answer.
Half of the neurons formed in the embryo are eliminated because of _____________ | [
"disease",
"contraction",
"competition",
"cell death"
] | C | |
SciQ | SciQ-3190 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What do omnivores eat? | [
"only plants",
"only seafood",
"only animals",
"plants & animals"
] | D | Omnivores are heterotrophs that consume both plants and animals. They include crows and human beings. The grizzly bears pictured in Figure below are also omnivores. |
SciQ | SciQ-3191 | geophysics, plate-tectonics
Title: Equatorial bulge and tectonic plates It is well known that the Earth is not a sphere, but rather it bulges at the equator. Also it is well known that the Earth's crust is composed of 7 or 8 (depending on definition) major tectonic plates, which are able to move on top of the asthenosphere, the upper layer of the Earth's mantle.
Due to the equatorial bulge, it would seem as though plates near the equator should not be able to drift away from the equator, and plates away from the equator should not be able to drift near the equator, since they will not be of the right shape to fit over these portions of the Earth. So how are the plates able to drift to and from the equator when the surface of the Earth is shaped differently there? The plates are not as rigid as you think. You seem to be imagining the situation as something like this: I boil an egg and take the shell off in pieces, but I can't take a piece of shell from the end and make it lay flat on the side of the egg. However, rock is not that rigid on scales of thousands of kilometres and millions of years (I don't think there exists any material which would be that rigid). Also, Earth's equatorial bulge is tiny relative to its diameter -- less than 50km. Tectonic plates move very slowly, and there is plenty of time for them to deform as they move.
The following is multiple choice question (with options) to answer.
Upwelling mantle at the mid-ocean ridge pushes plates in which direction? | [
"inward",
"westward",
"outward",
"eastward"
] | C | Plates move for two reasons. Upwelling mantle at the mid-ocean ridge pushes plates outward. Cold lithosphere sinking into the mantle at a subduction zone pulls the rest of the plate down with it. |
SciQ | SciQ-3192 | ecology
Title: Do invasive species cause long-term damage to ecosystems they invade? Growing up in the U.S., I was warned at various times of the dire consequences of a variety of introduced pests (usually insects).
Japanese beetles, gypsy moths, and most recently the brown marmorated stink bug are all introduced pests that, at various times, were described as serious threats to our ecology.
These threats aren't confined to arthropods, either. The giant African land snail is causing a stir in Florida (indeed, Florida seems to suffer from an excessive variety of introduced species.
"Lack of native predators" is frequently cited as the primary reason many invasive species are considered such a risk to the ecology.
I understand that these introduced species can place tremendous pressure on native species that fill similar ecological niches, and may even push these species out of the region due to competition for food and habitat. However, do the overall ecologies that these species are introduced to adjust over long periods of time?
The numbers of Japanese beetles and gypsy moths don't seem anywhere as high as when I was a child. Has the ecosystem adjusted, or has the overpopulation self-corrected as the species ran low on food through over-consumption? Or are the populations still just as problematic now as they were 30 years ago, and I just am not seeing the bigger picture?
What is the long-term impact that we've seen from invasive, introduced species? Is there a significant difference on the long-term impact between introduced flora, arthropods, or mammals? The answer really depends on how you think of invasive. One extreme answer is to say that all things are relative, and that the concepts of local and invasive are all relative. This matters to a certain extent because ecologists draw a fuzzy line between invasive and naturalized. You could start with some basic species that we all think of as either good, local, or neutral. Take the earthworm. Most people think of it as a common native species, but the earthworm is actually an invasive species that has radically changed much of North America that came over with the Europeans. Similarly, brown trout are also invasive, coming to the US in the 1800's.
The following is multiple choice question (with options) to answer.
Why are exotic species also called invasive species? | [
"imitate other species",
"help other species",
"threaten other species",
"disregard other species"
] | C | conditions in the new environment, threatening the species that exist there. For this reason, exotic species are also called invasive species. Exotic species can threaten other species through competition for resources, predation, or disease. |
SciQ | SciQ-3193 | homework, reproduction, embryology
Title: Which process is needed to complete male reproductive development? In order to properly complete male reproductive development:
A. primordial germ cells must begin Meiosis I in utero.
B. Sertoli cells must produce testosterone.
C. Dihydrotestosterone must masculinize Wolffian duct derivatives
D. the paramesonephric ducts must degenerate
E. the metanephros must form the genital epithelium
My attempt: I think the answer is C because testosterone turns into DHT which then masculinzing the wolffian duct. Other people I am studying with claim the answer is D (which is true) except that I dont think the loss of the paramesonephric duct is needed to complete male repro development. Regarding option C:
Although it is correct that testosterone is converted into DHT, it is the former, not the latter, which is responsible for differentiation of the mesonephric (a.k.a. Wolffian) ducts:
Between 8 and 12 weeks, the initial secretion of testosterone stimulates mesonephric ducts to transform into a system of organs—the epididymis, vas deferens, and seminal vesicle—that connect the testes with the urethra.*
DHT (dihydrotestosterone) is produced in the Leydig cells by the 5α-Reductase enzyme. It is required for induction of the external male genitalia (urethra, penis, and scrotum) and prostate from the embryonic ureteral groove, and for testicular descent into scrotum.
Regarding option D:
Sertoli cells secrete Anti Müllerian Hormone (AMH), which causes degeneration of the müllerian (a.k.a. paramesonephric) ducts between weeks 8 and 10. It is normal to speak about degeneration of the müllerian ducts as a defining aspect of male embryology, and thus I believe answer D is correct. Your point is taken, however:
Nevertheless, small müllerian duct remnants can be detected in the adult male, including a small cap of tissue associated with the testis, called the appendix testis, and an expansion of the prostatic urethra, called the prostatic utricle.*
The following is multiple choice question (with options) to answer.
The process of producing mature sperm is called what? | [
"spermatogenesis",
"ketoacidosis",
"spermatosis",
"glycogenolysis"
] | A | The process of producing mature sperm is called spermatogenesis . Sperm are produced in the seminiferous tubules of the testes and become mature in the epididymis . The entire process takes about 9 to 10 weeks. You can watch an animation of spermatogenesis at this link: http://wps. aw. com/bc_martini_eap_4/40/10469/2680298. cw/content/index. html . |
SciQ | SciQ-3194 | Finally, the following are theorems of propositional logic: \begin{align} & \neg (p \wedge \neg p) \\ & (p \wedge \neg p) \to q \\ \end{align} So, from a falsehood, you can prove anything. If a theory is inconsistent, then for some sentence $p$ it proves both $p$ and $\neg p$. In an inconsistent theory, anything and everything is provable.
To paraphrase Terry Tao explanation: $A \, \Longrightarrow \, B$ means intuitively "B is not more false than A". So if $A$ is false, then nothing is more false, any $B$ is no more false than $A$, and the implication is true.
• Ha, good point. Why SHOULD B be more false than A? Or more true thereafter. Well, it probably shouldn't :) – user2901512 Oct 12 '15 at 18:21
Turn the table around; what can we infer if A→B is true?
A→B | A | B
-----+---+---------------
T | T | T
T | F | No information
On the assumption that both rows are possible, we infer that F→F and F→T must have the same truth value. (and also, that T→F is false)
Similarly,
A→B | A
-----+----------------
T | No information
and therefore F→F and F→T can't be false.
A similar justification comes from how you prove A→B; a typical method is:
• Assume A is true
• ...
• Conclude B is true
and any (valid) argument of this form counts as a proof of A→B.
Since such a proof doesn't consider the possibility that A is false, the only way this could possibly work is if you don't need to consider that possibility: that is, if F→B is guaranteed to be true, always.
There are some good answers up there. I just want to add a tiny bit:
The following is multiple choice question (with options) to answer.
Unlike theories, which are proved true, what are often falsified? | [
"samples",
"hypotheses",
"controls",
"conclusions"
] | B | |
SciQ | SciQ-3195 | cell-biology, organelle
Title: Univocal identifying of a plant cell We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts in order to justify my statement.
Now in the exercise, we first had to identify the parts of a cell (which was shown in form of an image) and then in part b) reason whether it was an animal or plant cell.
I had identified a chloroplast and a vacuole and stated that the only cell with this organelles was the plant cell. My teacher answered that I had missed the fact, that the cell had also a cell wall (which is indeed a difference between plant and animal cells).
My question is
Is the fact that the cell had a cell wall necessary in my argumentation, i.e. are there other cells having chloroplasts and a vacuole without being a plant cell?
Could you provide a source which supports, or doesn't support my statement so that I can show it to my teacher?
Thanks in advance Your teacher is right, chloroplasts and vacuoles are not sufficient to define a plant cell.
Amoeba have both chloroplasts (McFadden et al, PNAS, 1994) and vacuoles (Day, J. Morphology, 1927) but they are not plants - and they do not have a cell wall.
Sea slugs eat algae and can "steal" their plastids and keep them working for weeks/months, effectively becoming photosynthetic animals for a while. This is called kleptoplastidy (Pillet, Mob. Genet. Elements, 2013).
The following is multiple choice question (with options) to answer.
What living things have cell walls containing cellulose and plastids such as chloroplasts? | [
"reptiles",
"mammals",
"plants",
"animals"
] | C | Plants have eukaryotic cells with large central vacuoles, cell walls containing cellulose, and plastids such as chloroplasts and chromoplasts. Different types of plant cells include parenchymal, collenchymal, and sclerenchymal cells. The three types differ in structure and function. |
SciQ | SciQ-3196 | fusion
Title: Where does the energy produced by fusion come from? Fission, in layman's (or "initiate's") terms, is easy enough to understand; a large atom with a lot of protons and neutrons requires a large amount of force provided by the strong interaction to overcome electromagnetism and keep the nucleus together. The necessary energies were imparted to the atom during its formation, which we can replicate to some degree within a nuclear reactor; a combination of heat and fast-moving free protons/neutrons recaptured by the atoms of the fuel turns uranium into plutonium, even as the actual atom-splitting produces much lighter krypton and barium isotopes (or a host of other possibilities, some more likely than others, as with many other types of reactions). That atom-splitting, by the way, reduces the size of the resulting nuclei, and therefore reduces the amount of strong interaction force required to contain them; the leftover energy is released as a high-frequency gamma photon.
Fusion, however, is an odder beast. A fusion reaction requires a large amount of starting energy; enough to strip the electrons off of the deuterium/tritium nuclei and form plasma. That heat is also enough to accelerate the particles fast enough that when they collide, the initial electromagnetic repulsion is overcome and the strong interaction binds them together.
Now, that's a lot of energy required; the Sun's inner core where most of the fusion occurs is estimated to be about 15 million Kelvin. The reaction, however, doesn't seem to release any energy, based at least on this simplistic explanation. Now, obviously that's wrong; pretty much all the energy we have available to us right now is, however indirectly, a result of the Sun bathing us in the energy from nuclear fusion. The rest of it, such as from nuclear fission, is also star-based, via creation of superheavy elements in stellar nucleogenesis.
The following is multiple choice question (with options) to answer.
Where does the energy from an atomic bomb come from? | [
"neutron",
"isotope of atom",
"nucleus of atom",
"electron shell"
] | C | An atomic bomb explodes and generates a huge mushroom cloud. The tremendous energy released when the bomb explodes is incredibly destructive. Where does all the energy come from? The answer is the nucleus of the atom. |
SciQ | SciQ-3197 | hydrology, rivers, dams
Title: Do dams reduce the flow of river downstream? There is a conflict between Egypt and Ethiopia, because the latter wants to build a dam on the Nile river. Citing this article:
[Egypt] fears the Nile dam will reduce its share of the river and leave the
country with dwindling options as it seeks to protect its main source
of fresh water.
What do they mean by "reduce its share of the river"? As far as I understand, the dam will create a reservoir, which will initially divert some water to be filled, but once that is done, the flow of the river should be the same. Is Egypt worried about this initial reduction, or do dams somehow reduce the flow of a river?
If so, what is the mechanism? I would guess that this is due to increased evaporation from the river, since the reservoir has a bigger surface than the usual river, but then again, it also collects more rain. Once a dam has been constructed in a river, the natural flow of water will be disrupted.
You correctly state that initially there will be a period required for the dam to fill. Until then, little of no water will flow beyond the dam.
Dams are created for one or more of three reasons:
To supply potable water to a population of humans for domestic or
industrial purposes.
For agricultural purposes.
To generate hydro-electricity.
The following is multiple choice question (with options) to answer.
Removal of dams on rivers is an example of what? | [
"restoration",
"reproduction",
"evolution",
"renewal"
] | A | 21.3 Preserving Biodiversity Five mass extinctions with losses of more than 50 percent of extant species are observable in the fossil record. Recent extinctions are recorded in written history and are the basis for one method of estimating contemporary extinction rates. The other method uses measures of habitat loss and species-area relationships. Estimates of contemporary extinction rates vary but are as high as 500 times the background rate, as determined from the fossil record, and are predicted to rise. There is a legislative framework for biodiversity protection. International treaties such as CITES regulate the transportation of endangered species across international borders. Legislation within individual countries protecting species and agreements on global warming have had limited success; there is at present no international agreement on targets for greenhouse gas emissions. In the United States, the Endangered Species Act protects listed species but is hampered by procedural difficulties and a focus on individual species. The Migratory Bird Act is an agreement between Canada and the United States to protect migratory birds. The non-profit sector is also very active in conservation efforts in a variety of ways. Conservation preserves are a major tool in biodiversity protection. Presently, 11 percent of Earth’s land surface is protected in some way. The science of island biogeography has informed the optimal design of preserves; however, preserves have limitations imposed by political and economic forces. In addition, climate change will limit the effectiveness of present preserves in the future. A downside of preserves is that they may lessen the pressure on human societies to function more sustainably outside the preserves. Habitat restoration has the potential to restore ecosystems to previous biodiversity levels before species become extinct. Examples of restoration include reintroduction of keystone species and removal of dams on rivers. Zoos have attempted to take a more active role in conservation and can have a limited role in captive breeding programs. Zoos also have a useful role in education. |
SciQ | SciQ-3198 | life, replication
Title: What is the name of the smallest self-replicating thing? Some time last year, I found an article on Wikipedia about the smallest something to be able to reproduce.
I don't remember exactly what it was, but I am fairly certain that after the initial discovery another of the previous organism (this one slightly smaller) was discovered.
I think that the smallest something might have been the smallest self-replicating protein, or smallest self-replicating molecule, or something like that.
It was not mentioned in this thread: Which organism has the smallest genome length?
It had a strange, stand-out name and I believe it was discovered in the 90s. You're probably thinking of the Spiegelman Monster. It was actually discovered in 1965, but it was discovered that it became shorter over time in 1997.
It also wasn't included in that thread, and it has a strange name.
http://en.wikipedia.org/wiki/Spiegelman_Monster
The following is multiple choice question (with options) to answer.
What is considered the smallest unit of life? | [
"proteins",
"cell",
"particle",
"molecule"
] | B | CHAPTER SUMMARY 4.1 Studying Cells A cell is the smallest unit of life. Most cells are so tiny that they cannot be seen with the naked eye. Therefore, scientists use microscopes to study cells. Electron microscopes provide higher magnification, higher resolution, and more detail than. |
SciQ | SciQ-3199 | 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 living things are considered photoautotrophs because they use sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates? | [
"plants",
"protazoa",
"bacteria",
"moulds"
] | A | Solar Dependence and Food Production Some organisms can carry out photosynthesis, whereas others cannot. An autotroph is an organism that can produce its own food. The Greek roots of the word autotroph mean “self” (auto) “feeder” (troph). Plants are the best-known autotrophs, but others exist, including certain types of bacteria and algae (Figure 5.2). Oceanic algae contribute enormous quantities of food and oxygen to global food chains. Plants are also photoautotrophs, a type of autotroph that uses sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. All organisms carrying out photosynthesis require sunlight. |
SciQ | SciQ-3200 | 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.
Acids are molecular compounds that dissolve in water to produce hydronium ions and what else? | [
"an alkali",
"a neutron",
"an anion",
"a proton"
] | C | Acids are molecular compounds that dissolve in water to produce hydronium ions and an anion. |
SciQ | SciQ-3201 | thermodynamics, water, phase-transition, phase-diagram
Title: Vaporization - phase diagram I understand what boiling and vaporization is. But what puzzles me is the phase diagram.
When I spill a glass of water in my room, it will soon vaporize, though there was normal atmospheric pressure and 20 °C. If you look in phase diagram of water, it should be still liquid at this point.
I understand that molecules of water escape the surface and turn into vapor, but... is the phase diagram of water wrong then? The temperature and pressure didn't change around that spilled water and still it turns into gas, although (looking at the phase diagram), it should be liquid. The phase diagram has equilibrium states for pure water, vapor, and both at saturation. You have water exposed to atmospheric gases, so the pressure is not that of pure vapor. The water will evaporate trying to create a partial pressure of vapor equal to the vapor pressure for saturated water at the water temperature. If the surface is open to flow of fresh air, this vapor pressure is not achieved, and the water slowly evaporates away.
The following is multiple choice question (with options) to answer.
What is the terme for water vapor changing to liquid water? | [
"freezing",
"evaporation",
"condensation",
"transubstantiation"
] | C | |
SciQ | SciQ-3202 | electrochemistry
Title: What causes electrons to move from zinc to copper? Here is something that no video in youtube about electrochemistry can explain me about galvanic cells.
Suppose we have $\ce{Zn}$ metal immerse in $\ce{Zn^{2+}}$ in one side, then $\ce{Cu}$ metal immerse in $\ce{Cu^{2+}}$ in the other side. Then, if we link the $\ce{Zn}$ metal to $\ce{Cu}$ metal with some conductor wire, electrons will flow from the $\ce{Zn}$ metal to the copper wire, but this will stop quickly without a salt bridge.
My question is why do the electrons move from $\ce{Zn}$ metal through the wire to the $\ce{Cu}$ metal in the first place? What causes that? There is no reaction since the electrons will only flow one way in the wire. When you connect the zinc metal to the copper metal with a wire, there is a voltage potential generated between them, just like in a thermocouple.
From Wikipedia:
Any junction of dissimilar metals will produce an electric potential related to temperature.
In this case, we don't care about the temperature effects.
When a salt bridge is placed between the solution, then the electrons are carried by the anions in the solution from one electrode to the other electrode.
So the zinc metal releases electrons when it dissolves, which travel through the wire easily, to the copper. The $\ce {Cu^{2+}}$ in solution grabs the electrons from the copper electrode, adding copper metal to the electrode. Since there is now more negative ions in this solution, the anions move across the bridge to the zinc electrode. The anions attack the zinc metal, causing the zinc to loose electrons when it dissolves.
I'm not sure what starts the reaction, nor why the zinc dissolves easily.
The following is multiple choice question (with options) to answer.
What processes involve a transfer of electrons between the wire and the solution? | [
"thermal",
"electrochemical",
"magnetic",
"radioactive"
] | B | Electrochemistry is the study of chemical processes that occur at the interface between an electron conductor, such as a wire, and a solution of electrolytes, which is often simply an ionic substance dissolved in water. Electrochemical processes involve a transfer of electrons between the wire and the solution. These reactions can be used to create electrical power, to purify metals, and to carry out a number of useful chemical transformations. |
SciQ | SciQ-3203 | cardiology, embryology, pain, central-nervous-system
Title: At what stage is the nervous system developed enough to interpret neuronal signals as 'pain'? According to this article in Live Science, one of the reasons the fetus can't feel pain until 19 weeks is because the nervous system isn't fully developed.
But according to this article, the heart starts beating at day 16.
And according to this article, the nervous system controls the rate beating of the heart.
Then my question is, **how can it be assured that the nervous system isn't developed until 19 weeks, when the nervous system controls the heart beating rate since day 16? First, there is some confusion on your part about heart cells and pain perception. Heart cells generate an action potential intrinsically; they do not need the central nervous system to beat (your second article explains this; read the part about the importance of calcium.) So yes, long before a fetus can feel pain, the heart is beating, because there must be circulation of nutrients throughout the embryo.
Secondly, the vagus nerve and sympathetic nerves can affect heart rate (the former by slowing it down when firing). These nerves start to reach their endpoints late in week 4 of development. So 19 days is not correct.
Cardiac sympathetic system
Although the primitive human heart starts to beat at 21 to 22 d, heart development continues to day 50, and it is near the end of this period, during the fifth week, that thoracic neural crest cells migrate from the neural tube through the somites and form aggregations (ganglia) near the dorsal aorta. [emphasis mine]
To experience pain, however, requires maturation of certain parts of the brain, most importantly, part of the thalamus and the cerebral cortex:
Current theories of pain consider an intact cortical system to be both necessary and sufficient for pain experience. In support are functional imaging studies showing that activation within a network of cortical regions correlate with reported pain experience. Furthermore, cortical activation can generate the experience of pain even in the absence of actual noxious stimulation. These observations suggest thalamic projections into the cortical plate are the minimal necessary anatomy for pain experience. These projections are complete at 23 weeks' gestation. [emphasis mine]
The following is multiple choice question (with options) to answer.
What happens when development of nervous system is disturbed? | [
"neurodevelopmental disorders",
"vascular disorders",
"muscular disorders",
"neurochemical disorders"
] | A | Neurodevelopmental Disorders Neurodevelopmental disorders occur when the development of the nervous system is disturbed. There are several different classes of neurodevelopmental disorders. Some, like Down Syndrome, cause intellectual deficits. Others specifically affect communication, learning, or the motor system. Some disorders like autism spectrum disorder and attention deficit/ hyperactivity disorder have complex symptoms. Autism Autism spectrum disorder (ASD) is a neurodevelopmental disorder. Its severity differs from person to person. Estimates for the prevalence of the disorder have changed rapidly in the past few decades. Current estimates suggest that one in 88 children will develop the disorder. ASD is four times more prevalent in males than females. |
SciQ | SciQ-3204 | species-identification, mycology
Title: Mushroom Identificaton(USA) I need help identifying a perculiar species of mushroom found in my yard today. Color is orange-yellow, around 3-4 inches total radius, its a cluster of tiny to medium mushrooms. They were found near an oak tree. Location is southern Georgia, USa. These could be specimens of Omphalotus Illudens based on the orange/yellow color, the time of the year, their association with decaying wood (an oak in this case) and your location (eastern North America)
You can read more about these species in this reference: Messiah College
The following is multiple choice question (with options) to answer.
What color is the fungus in blue cheese? | [
"green",
"pink",
"blue",
"purple"
] | C | Blue cheese is blue because of the fungus growing throughout it. |
SciQ | SciQ-3205 | special-relativity, kinematics, space-travel, asteroids
Title: How a spacecraft travelling near light speed avoid asteroids? How would a spacecraft traveling near light speed avoid a (relatively dense group of) asteroids? Or suppose such spacecraft is designed, how would the physics work for steering it inside such a "cloud" of asteroids?
If it simply by designing the spacecraft to have huge acceleration, wouldn't that mean lots of constraints on the material the spacecraft can be made of? The speed of protons in the LHC is at 99.9999991% of the speed of light.
You can see what happens when a proton hits a proton travelling in the opposite direction at those speeds.
A candidate event in the search for the Higgs boson, showing two electrons and two muons (Image: CMS/CERN)
Now the spacecraft in question presumably is traveling at a similar fraction of the speed of light with respect with the asteroid cluster. 8 TeV (the energy of the proton in the above interaction) is still enormous energy at contact. What will happen is that the individual protons of the spacecraft will react as elementary particles creating an enormous number of secondaries similar to the image above. Immediate destruction of spacecraft.
Avoidance can only happen by detecting the presence of the cluster some fraction of a light year away from it and plot course accordingly.
IMO the main danger to such a fast traveling spacecraft will come from the low density ions in space, which will produce such interactions inimical to life. A strong magnetic field might throw away ions, but there are also neutral particles in the cosmic dust which cannot be stopped easily. A very strong and very massive shielding system will be necessary.
It's important to also note asteroid fields are not very dense at all. It's not like the objects in Saturn's rings or the fictional asteroid field in Star Wars. The asteroids are incredibly far in between in most cases so your chances of hitting an asteroid aren't really much greater at a higher velocity, it will just cause much more damage if it does hit you. So the biggest problem as stated above would be the particles in the interstellar medium. Of course if you have the technology to travel in such a manner in the first place you would have access to technologies we haven't yet conceived and it could be that at that level of technology this wouldn't be an issue.
The following is multiple choice question (with options) to answer.
Not even light can escape from what extremely dense object sometimes found in deep space? | [
"large holes",
"star holes",
"light holes",
"black holes"
] | D | Black holes Black holes are objects having such large gravitational fields that things can fall in, but nothing, not even light, can escape. Bodies, like the Earth or the Sun, have what is called an escape velocity. If an object moves straight up from the body, starting at the escape velocity, it will just be able to escape the gravity of the body. The greater the acceleration of gravity on the body, the greater is the escape velocity. As long ago as the late 1700s, it was proposed that if the escape velocity is greater than the speed of light, then light cannot escape. Simon Laplace (1749–1827), the French astronomer and mathematician, even incorporated this idea of a dark star into his writings. But the idea was dropped after Young’s double slit experiment showed light to be a wave. For some time, light was thought not to have particle characteristics and, thus, could not be acted upon by gravity. The idea of a black hole was very quickly reincarnated in 1916 after Einstein’s theory of general relativity was published. It is now thought that black holes can form in the supernova collapse of a massive star, forming an object perhaps 10 km across and having a mass greater than that of our Sun. It is interesting that several prominent physicists who worked on the concept, including Einstein, firmly believed that nature would find a way to prohibit such objects. Black holes are difficult to observe directly, because they are small and no light comes directly from them. In fact, no light comes from inside the event horizon, which is defined to be at a distance from the object at which the escape velocity is exactly the speed of light. The radius of the event horizon is known as the Schwarzschild radius R S and is given by. |
SciQ | SciQ-3206 | 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.
The nucleus is comprised primarily of? | [
"faith",
"matter",
"energy",
"empty space"
] | D | While the great majority of the alpha particles did pass straight through the foil with no deflection, to everyone’s surprise, some alpha particles were deflected. In fact, some alpha were bounced almost straight backward by the foil. Rutherford, using Coulomb’s law and Newton’s laws found that the results could be explained only if all the positive charge of the atom were concentrated in a tiny, central core, now called the nucleus . Rutherford’s model of the atom is therefore, called the nuclear model of the atom. All of the positive charge and essentially all of the mass of the atom are in its nucleus. The atom is 10,000 times as large as the nucleus and is mostly empty space. It was known that electrons are outside the nucleus but how the electrons were arranged in an atom was still a mystery. |
SciQ | SciQ-3207 | breathing
Title: Why does the pulmonary artery have higher glucose concentration than the pulmonary vein? If the pulmonary artery have higher glucose concentration than the pulmonary vein, does it mean glucose will be consumed during gas exchange?
That confused me because gas exchange is something like diffusion and shouldn't consume any glucose Gas exchange doesn't but the cells of the tissue it occurs in do consume glucose, even the cells in the walls of the artery will consume some. The cells in the lungs still need to be fed and only one of those two vessels has flow going into the tissue so it is the one that has to carry that glucose into the tissue.
The following is multiple choice question (with options) to answer.
What in mammalian lungs, increases the surface area for gas exchange? | [
"thorax",
"bronchi",
"alveoli",
"bronchioles"
] | C | The lungs of mammals are unique in having alveoli. These are tiny, sac-like structures. Each alveolus is surrounded by a network of very small blood vessels (see Figure below ). Because there are millions of alveoli in each lung, they greatly increase the surface area for gas exchange between the lungs and bloodstream. Human lungs, for example, contain about 300 million alveoli. They give the lungs a total surface area for gas exchange of up to 90 square meters (968 square feet). That’s about as much surface area as one side of a volleyball court!. |
SciQ | SciQ-3208 | condensed-matter
Title: If a liquid is compressed enough, would it become solid? If a liquid were to be compressed so tensely that the particles had no room to move, would it then become a solid?
Also, would the same happen with a gas? It depends on the substance. It is easy to work out though from the relevant phase diagram.
Isothermally increasing the pressure of liquid CO$_2$ will create a solid phase (dry ice). But increasing the pressure of liquid water will not create ice.
A gas-to-solid transition with increasing pressure is a process called deposition. It will happen with most substances if the temperature is sufficiently low.
The following is multiple choice question (with options) to answer.
What is the process by which some solids transition directly into gases? | [
"vaporization",
"articulation",
"sublimation",
"amplification"
] | C | Sublimation and Deposition Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublime at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes and a vivid purple vapor forms (Figure 10.27). The reverse of sublimation is called deposition, a process in which gaseous substances condense directly into the solid state, bypassing the liquid state. The formation of frost is an example of deposition. |
SciQ | SciQ-3209 | biochemistry, neuroscience, brain, neuroanatomy
Title: The human brain in numbers I: neurons Even though knowing the number of neurons in a functional unit or with the same function is not of main importance, it may be interesting to know their orders of magnitude, especially in the human brain. For example:
|------------------|------------------|
| cerebellum | 100,000,000,000 |
| cortex | 20,000,000,000 |
| telencephalon | 10,000,000,000 |
| brainstem | 1,000,000,000 |
| sensory neurons | |
| haptic | 500,000,000 |
| visual | 100,000,000 |
| auditory | 2,000 |
| limbic system | |
| amygdala | 10,000,000 |
|------------------|------------------|
The following is multiple choice question (with options) to answer.
What are the two main parts of the human nervous system? | [
"brain, heart",
"lungs, brain",
"lungs, spinal cord",
"brain, spinal cord"
] | D | |
SciQ | SciQ-3210 | waves, acoustics, frequency, resonance
Title: Can't understand Resonance in an Air Column
In this image about resonating air column in my book, they say that resonance occurs at those specific lengths marked in the diagram. However,
its also said that natural frequency of air column decreases with increase in length.
resonance occurs when the natural frequency of tuning fork is equal to the natural frequency of the air column.
But in the figure, the frequency is same for $\frac{\lambda}4$, $\frac{3\lambda}4$ and $\frac{5\lambda}4$. How is that so? Shouldn't the tuning fork resonate with the air column at only one length, as the natural frequency of the air column is different for different lengths? Why is it not like the picture below for different lengths? An air column of given length has many resonant frequencies. These are called the fundamental and the harmonics. The fundamental has the longest wavelength that can fit in the column and satisfy the right conditions at the two ends. In this example one end has to have no air oscillation (at the closed end) and the other has to have a maximum air oscillation (at the open end).
The fundamental thus has a longer wavelength and therefore a lower frequency as the air column gets longer.
The image shows three cases which all have the same wavelength and thus the same frequency: the fundamental of an air column of length $l_1$, then the first harmonic of an air column of length $3 l_1$ and the second harmonic of the air column of length $5 l_1$. Those longer air columns do have lower fundamental frequencies, but the person drawing the diagram was interested in the fact that a tuning fork of some given frequency will resonate with many different air columns, when the tuning fork hits the note of one of the harmonics.
The term 'natural frequency' is normally used for the fundamental.
The following is multiple choice question (with options) to answer.
In frequency, the larger the air column, the larger the what? | [
"wavelength",
"mass",
"gravity",
"absorption"
] | A | a) The water forms the bottom of the tube and thus where the node of the wave will be. Thus the air column is where the sound wave can exist. The larger the air column, the larger the wavelength. Frequency is inversely proportional to wavelength, thus the tube with the smallest air column will have the highest frequency. So the answer is tube C. |
SciQ | SciQ-3211 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
Subducting plate and epicenter are terms related to what phenomenon? | [
"tidal wave",
"hurricane",
"earthquake",
"eruption"
] | C | A cross section of earthquake epicenters. The depth outlines the subducting plate. There are shallow, intermediate, and deep earthquakes. |
SciQ | SciQ-3212 | 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 is the process by which organisms break down chemicals to make food energy? | [
"electrolysis",
"excretion",
"chemosynthesis",
"gametogenesis"
] | C | In chemosynthesis, organisms break down chemicals to make food energy. |
SciQ | SciQ-3213 | genetics
So the modern definition of a phenotype is the observable characteristics of an organism, anatomical, physiological or behavioral. The first 2 points are easily accepted and uncontroversial. But there is debate about what exactly should be included in "behavior". I'm going to ignore behavior for now.
An important point, and I think this is where there is disagreement between Remi.b and me, is that a phenotype must have a genetics basis. I realize this is not explicitly mentioned in any definition, but that is very much the way people mean it. And if not, the definition is totally meaningless. Take the example of a monkey missing a finger congenitally. This is a phenotype, it is due to its genes. If the monkey is missing a finger due to a fight, this is not a phenotype because genes have nothing to do with it (again, ignoring behavior for now).
So, in my opinion, what would not be a phenotype is something that you could conclusively prove to have no genetics basis whatsoever. That's an extremely (impossible) hard case to make. But in retrospect I was perhaps to quick to include behavior in the definition, and this is due to my own biases as a behavioral neuroscientist.
I think this is the narrow definition of phenotype and I don't think anyone would disagree up to that point. You might notice that there has been no mention of evolution so far. It is because genetics and evolution have been developed independently, and even though everybody was quite aware they must be 2 sides of the same coin evolution is not directly relevant to the genotype/phenotype distinction.
The following is multiple choice question (with options) to answer.
What is the term for an organism’s underlying genetic makeup, consisting of both the physically visible and the non-expressed alleles? | [
"divergency",
"genotype",
"trait map",
"phenotype"
] | B | Phenotypes and Genotypes Two alleles for a given gene in a diploid organism are expressed and interact to produce physical characteristics. The observable traits expressed by an organism are referred to as its phenotype. An organism’s underlying genetic makeup, consisting of both the physically visible and the non-expressed alleles, is called its genotype. Mendel’s hybridization experiments demonstrate the difference between phenotype and genotype. For example, the phenotypes that Mendel observed in his crosses between pea plants with differing traits are connected to the diploid genotypes of the plants in the P, F1, and F2 generations. We will use a second trait that Mendel investigated, seed color, as an example. Seed color is governed by a single gene with two alleles. The yellow-seed allele is dominant and the green-seed allele is recessive. When true-breeding plants were cross-fertilized, in which one parent had yellow seeds and one had green seeds, all of the F1 hybrid offspring had yellow seeds. That is, the hybrid offspring were phenotypically identical to the true-breeding parent with yellow seeds. However, we know that the allele donated by the parent with green seeds was not simply lost because it reappeared in some of the F2 offspring (Figure 8.5). Therefore, the F1 plants must have been genotypically different from the parent with yellow seeds. The P plants that Mendel used in his experiments were each homozygous for the trait he was studying. Diploid organisms that are homozygous for a gene have two identical alleles, one on each of their homologous chromosomes. The genotype is often written as YY or yy, for which each letter represents one of the two alleles in the genotype. The dominant allele is capitalized and the recessive allele is lower case. The letter used for the gene (seed color in this case) is usually related to the dominant trait (yellow allele, in this case, or “Y”). Mendel’s parental pea plants always bred true because both. |
SciQ | SciQ-3214 | human-anatomy
Title: Difference between Appendix and the Cecum? What's the difference between an appendix and a cecum, and what are their functions? In herbivores the Cecum is an area that stores plant matter and helps digest it via symbiotic bacteria. Carnivores have smaller Cecums because meat is easier to digest than plant matter. In humans the Cecum is also an anatomical landmark that delineates the change from small intestine (a digesting organ) to the large intestine (mostly a capacity/storage organ).
The Appendix is a small, previously thought "superfluous" fleshy worm-shaped organ at the junction between the small and large intestines. Recent research posits that the appendix is sort of a harbor for a person's gut flora that can re-populate the intestines should the existing bacteria die or get removed (diarrhea being the most common cause). It can also become infected, inflamed, and require surgery to remove (Appendicitis).
The following is multiple choice question (with options) to answer.
Which organ is a wide tube connecting the small intestine with the anus? | [
"stomach",
"rectum",
"jejunum",
"large intestine"
] | D | The large intestine is a wide tube that connects the small intestine with the anus. In adults, the large intestine is about 1.5 meters (5 feet) long. It is larger in width but shorter in length than the small intestine. |
SciQ | SciQ-3215 | everyday-chemistry, toxicity
Such oxidation reactions are catalyzed both by soluble metals such as iron and by light. Hydrogen sulfide also can combine with metals such as iron (Fe++) to precipitate as black iron sulfide (Figure 1 bottom; FeS and FeS2).
The following is multiple choice question (with options) to answer.
What is produced when sulfur and oxygen combine? | [
"Solid oxides",
"sulfur oxides",
"ethanol oxides",
"treatment oxides"
] | B | Sulfur oxides include sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ). Sulfur oxides are produced when sulfur and oxygen combine. This happens when coal burns. Coal can contain up to 10 percent sulfur. |
SciQ | SciQ-3216 | botany, plant-physiology
Title: Can any plant regenerate missing tissue? I have not yet found a plant that, when an insect eats a hole in one of its leaves, it can regenerate the lost tissue. Many plants will grow a new stem if the old one is cut, but it is not a perfect regeneration, and has no likeness in form to the previous stem. Are there any plants that can, even to a degree, regenerate missing tissue? In general, plant cells only undergo differentiation at special regions in the plant known as meristems. Two of the primary types of meristem are the root apical meristem (at the tips of roots) and the shoot apical meristem (at shoot tips)^. Within the shoot apical meristem the plant cells divide and begin to differentiate into different cell types (such as different cells of the leaf, or vascular cells). Later growth (of, say, a leaf) is largely a result of cell expansion (although cell division does still occur, but drops off as the leaf expands). Therefore, if you punch a hole in a leaf, it probably won't be filled in because the cells in that leaf have finished growing and dividing.
However, as a shoot grows, more meristems are created. These are found in the axillary buds, just above where the leaf meets the stem. The meristems in the axillary buds can grow to form branches. Different plants obviously make different numbers of branches, but there is a common control mechanism known as apical dominance, where the meristem at the tip of the shoot suppresses the growth of the lower axillary buds. This is why a shoot with no branches can be made to grow branches by cutting off the tip (gardeners often do this to make "leggy" plants more bushy).
All of that was a long explanation to say, no, a plant doesn't normally^^ regenerate in the sense of filling in cells that have gone missing. However, if you cut off a shoot, the next remaining bud might begin to grow and, in a sense, replace the part that was lost. In that case, an existing bud is recruited to form a new branch and replace lost functionality, but I wouldn't say that qualifies as regenerating missing tissue.
^There are other types of meristem as well.
The following is multiple choice question (with options) to answer.
Plant cells divide into two equal halves during what process? | [
"prokaryotes",
"cytokinesis",
"death",
"mitosis"
] | D | |
SciQ | SciQ-3217 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
What is the type of succession that happens after the destruction of a habitat? | [
"tertiary succession",
"secondary succession",
"primary succession",
"typical succession"
] | B | Sometimes ecological succession occurs in areas where life has already existed. These areas already have soil full of nutrients. Secondary succession is the type of succession that happens after something destroys the habitat, such as a flood or other natural disaster. Abandoning a field that was once used for agriculture can also lead to secondary succession ( Figure below ). In this case, the pioneer species would be the grasses that first appear. Lichen would not be necessary as there is already nutrient-rich soil. Slowly, the field would return to its natural state. |
SciQ | SciQ-3218 | inorganic-chemistry, nomenclature
Examples:
potassium phosphate, calcium chloride, magnesium cyanide
Answers: (hover to peek!)
$\ce{K3PO4, CaCl2, Mg(CN)2}$
Naming a covalent compound from its formula
Name the less electronegative element and then the more electronegative element ("carbon monoxide" but not "oxygen monocarbide")
Apply suffixes to anions in exactly the same way as we did for ionic compounds. ("sulfur hexafluoride" but not "sulfur fluoride") Also, keep the name all lowercase as before.
Use numerical prefixes.[3] Hence "dinitrogen tetroxide" for $\ce{N2O4}$ but not "nitrogen oxide". Here's the first ten suffixes: $$\begin{array}{|c|c|} \hline
\mathrm{prefix} & \mathrm{number}\\ \hline
\mathrm{mon(o)} & 1 \\
\mathrm{di} & 2 \\
\mathrm{tri} & 3 \\
\mathrm{tetr(a)} & 4 \\
\mathrm{pent(a)} & 5 \\
\mathrm{hex(a)} & 6 \\
\mathrm{hept(a)} & 7 \\
\mathrm{oct(a)} & 8 \\
\mathrm{non(a)} & 9 \\
\mathrm{dec(a)} & 10 \\
\hline
\end{array}$$ Note that:
the letter in parentheses is dropped when the anion begins with a vowel ("tetroxide", but not "tetraoxide")
we do not specify the mono- prefix for the first element ("carbon tetrachloride" but not "monocarbon tetrachloride")
we can construct similar numerical prefixes for larger counts by using the Greek system. Example: "undeca" for 11. Look at a larger list on Wikipedia.
The following is multiple choice question (with options) to answer.
The name of a monatomic cation is simply the name of the element followed by this word? | [
"laser",
"ion",
"bond",
"amine"
] | B | The name of a monatomic cation is simply the name of the element followed by the word ion. Thus, Na+ is the sodium ion, Al3+ is the aluminum ion, Ca2+ is the calcium ion, and so forth. We have seen that some elements lose different numbers of electrons, producing ions of different charges (Figure 3.3 "Predicting Ionic Charges"). Iron, for example, can form two cations, each of which, when combined with the same anion, makes a different compound with unique physical and chemical properties. Thus, we need a different name for each iron ion to distinguish Fe2+ from Fe3+. The same issue arises for other ions with more than one possible charge. There are two ways to make this distinction. In the simpler, more modern approach, called the Stock system, an ion’s positive charge is indicated by a roman numeral in parentheses after the element name, followed by the word ion. Thus, Fe2+ is called the iron(II) ion, while Fe3+ is called the iron(III) ion. This system is used only for elements that form more than one common positive ion. We do not call the Na+ ion the sodium(I) ion because (I) is unnecessary. Sodium forms only a 1+ ion, so there is no ambiguity about the name sodium ion. The second system, called the common system, is not conventional but is still prevalent and used in the health sciences. This system recognizes that many metals have two common cations. The common system uses two suffixes (-ic and -ous) that are appended to the stem of the element name. The -ic suffix represents the greater of the two cation charges, and the -ous suffix represents the lower one. In many cases, the stem of the element name comes from the Latin name of the element. Table 3.2 "The Common System of Cation Names" lists the elements that use the common system, along with their respective cation names. Table 3.2 The Common System of Cation Names. |
SciQ | SciQ-3219 | food, eggs, allergies
Title: Is it possible to be allergic to the yolk of an egg but not the egg white? At lunch one day, my friend had a hard boiled Easter egg. When he pealed it he squeezed the yolk, or yellow part, of the egg out. I asked him what on earth he was doing and he said, "I'm allergic to the yellow part of the egg not the white." I was very confused by this, he also sad he was allergic to tomatoes but could still eat pizza with sauce on it, apples but only the skins, and some other strange things. I didn't think this was possible at all. Can anyone explain this and tell me if it's even possible to be allergic to one part of an egg and not the other, or is it all in his head. If this is possible, is there an actual name for this condition? The protein composition of the egg white and egg yolk differ appreciably. Hence, it is plausible for one to countenance symptoms of indigestion when consuming the egg yolk as opposed to the albumen, egg whites. It is important to stress that your friend may only an indigestion towards egg yolks as opposed to an immune response to an antigen.
If we consider the protein family, the egg yolk comprises a family of phosvitins, a group of highly phosphorylated proteins capable of mustering iron and calcium metal cations - serving a role in embryo development.
These are primarily absent from the albumen which comprises (with an unexpected name!) a highest percentage of suspended ovalbumin, ovotransferrin and ovomucoid. As demonstrated by the American College of Allergy, Asthma & Immunology, it is feasible to suffer an intolerance towards the egg yolk and yet suffer no gastro-enteric indigestion to the egg whites.
More information regarding the American College is available from: https://acaai.org/allergies/types/food-allergies/types-food-allergy/egg-allergy
The following is multiple choice question (with options) to answer.
What is an extremely severe food allergy reaction? | [
"lymphocytes",
"sepsis",
"anaphylaxis",
"apoptosis"
] | C | Food allergies occur when the immune system reacts to substances in food as though they were harmful “foreign invaders. ” Foods that are most likely to cause allergies are pictured in Figure below , and include nuts, eggs, grains and milk. Symptoms of food allergies often include vomiting and diarrhea. Symptoms of food allergies include itching and swelling of the lips and mouth. More serious symptoms include trouble breathing. In some instances, a food allergy can trigger anaphylaxis, which is an extremely severe reaction. Emergency medical treatment is critical for this condition, which left untreated, can lead to death. |
SciQ | SciQ-3220 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
What do you call the formation of a water vapor pocket? | [
"coagulation",
"cavitation",
"precipitation",
"conduction"
] | B | |
SciQ | SciQ-3221 | nutrition, hematology, metabolism
Title: How does a glucose molecule enter the cell from blood vessel? The transporters in the plasma membrane of the cells promote the entry of glucose molecules from the extracellular matrix to the cytosol of the cell. Could someone explain how does the nutrient molecule enter the extracellular space from the blood vessel?
For instance, in the context of the pancreas, the walls of the blood vessel is fenestrated. The literature also provides evidence for the presence of connexon in the endothelium of the capillaries.
My doubt is, the nutrient molecule that diffuses from the blood vessel reaches the cytosol of the cell through
Diffusing through connexon ?(or)
Does it reach the interstitial matrix(the fluid surrounding the cells) and then uptaken by the transporters present in the plasma membrane of the cell? I think I understand your question, Natasha. In short, your own answer #2 is correct.
There are 3 spaces, and 2 pathways for glucose to pass from one to the next:
intracapillary plasma
extracellular fluid
the cytosol.
Ways glucose gets into the cell:
(2->3) To get from the ECF to the cytosol , glucose always needs a transport protein. These are the GLUTs. In two cases, the small intestine and kidney, these are part of a secondary active transport system based on the Na/K-ATPase. In the pancreas, it's GLUT2.
(1->2) To get from the capillary plasma to the ECF requires filtration, the process of applying hydrostatic pressure to the plasma and literally squeezing it like a sponge. The boundary of the "blood sponge" is the basement membrane. The membrane holds in the proteins, and lets anything dissolved in the watery serum (like glucose) through.
The Filtration Constant Kf is proportional to the percentage of the BM that is exposed in a given capillary, which varies by the type and other factors like histamine release.
The following is multiple choice question (with options) to answer.
Internal body fluids link exchange surfaces to what else? | [
"organs",
"ligaments",
"tissue",
"body cells"
] | D | |
SciQ | SciQ-3222 | electromagnetism, electricity, magnetic-fields
Title: Why does electricity flowing through a copper coil generate a magnetic field? Can some one please explain to me why electricity flowing though a copper coil generates a magnetic field or where I could possibly find that information? Are there other materials that produce a magnetic field when a current is run through them in a different shape? Thanks!
Can some one please explain to me why electricity flowing though a
copper coil generates a magnetic field or where I could possibly find
that information?
An electric current (a flow of electric charge) has an associated magnetic field regardless of the material (or space) the flow occurs in. This is a fundamental part of electromagnetism, rooted in observation, and quantified in Ampere's Law.
I wish to emphasize that this phenomenon is considered fundamental in nature, which means there cannot be a "more" fundamental explanation (if there were, electromagnetism would not be fundamental).
The following is multiple choice question (with options) to answer.
What magnetism is produced by electricity? | [
"electromagnetism",
"Charges",
"excitation",
"diffusion"
] | A | Magnetism produced by electricity is called electromagnetism . Today, electromagnetism is used in many electric devices. However, until electromagnetism was discovered, scientists thought that electricity and magnetism were unrelated. A Danish scientist named Hans Christian Oersted (pictured in the Figure below ) changed all that. He made the important discovery that electric current creates a magnetic field. But like many other important discoveries in science, Oersted’s discovery was just a lucky accident. |
SciQ | SciQ-3223 | botany, plant-physiology
Title: Can any plant regenerate missing tissue? I have not yet found a plant that, when an insect eats a hole in one of its leaves, it can regenerate the lost tissue. Many plants will grow a new stem if the old one is cut, but it is not a perfect regeneration, and has no likeness in form to the previous stem. Are there any plants that can, even to a degree, regenerate missing tissue? In general, plant cells only undergo differentiation at special regions in the plant known as meristems. Two of the primary types of meristem are the root apical meristem (at the tips of roots) and the shoot apical meristem (at shoot tips)^. Within the shoot apical meristem the plant cells divide and begin to differentiate into different cell types (such as different cells of the leaf, or vascular cells). Later growth (of, say, a leaf) is largely a result of cell expansion (although cell division does still occur, but drops off as the leaf expands). Therefore, if you punch a hole in a leaf, it probably won't be filled in because the cells in that leaf have finished growing and dividing.
However, as a shoot grows, more meristems are created. These are found in the axillary buds, just above where the leaf meets the stem. The meristems in the axillary buds can grow to form branches. Different plants obviously make different numbers of branches, but there is a common control mechanism known as apical dominance, where the meristem at the tip of the shoot suppresses the growth of the lower axillary buds. This is why a shoot with no branches can be made to grow branches by cutting off the tip (gardeners often do this to make "leggy" plants more bushy).
All of that was a long explanation to say, no, a plant doesn't normally^^ regenerate in the sense of filling in cells that have gone missing. However, if you cut off a shoot, the next remaining bud might begin to grow and, in a sense, replace the part that was lost. In that case, an existing bud is recruited to form a new branch and replace lost functionality, but I wouldn't say that qualifies as regenerating missing tissue.
^There are other types of meristem as well.
The following is multiple choice question (with options) to answer.
What is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate? | [
"cambium",
"meristem",
"epidermis",
"ganglion"
] | B | Most plants continue to grow as long as they live. They grow through a combination of cell growth and cell division (mitosis). The key to plant growth is meristem, a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Meristem allows plant stems and roots to grow longer (primary growth) and wider (secondary growth). |
SciQ | SciQ-3224 | bond, quantum-chemistry, molecular-orbital-theory
For example, the fact that $\ce{He2}$ molecule is not formed can be explained from its MO diagram, which shows that the number of electrons in antibonding and bonding molecular orbitals is the same, and since the destabilizing energy of the antibonding MO is greater than the stabilising energy of bonding MO, the molecule is not formed. This is the common line of reasoning you find at most places. Mathematical Explanation
When examining the linear combination of atomic orbitals (LCAO) for the $\ce{H2+}$ molecular ion, we get two different energy levels, $E_+$ and $E_-$ depending on the coefficients of the atomic orbitals. The energies of the two different MO's are:
$$\begin{align}
E_+ &= E_\text{1s} + \frac{j_0}{R} - \frac{j' + k'}{1+S} \\
E_- &= E_\text{1s} + \frac{j_0}{R} - \frac{j' - k'}{1-S}
\end{align} $$
Note that $j_0 = \frac{e^2}{4\pi\varepsilon_0}$, $R$ is the internuclear distance, $S=\int \chi_\text{A}^* \chi_\text{B}\,\text{d}V$ the overlap integral, $j'$ is a coulombic contribution to the energy and $k'$ is a contribution to the resonance integral, and it does not have a classical analogue. $j'$ and $k'$ are both positive and $j' \gt k'$. You'll note that $j'-k' > 0$.
This is why the energy levels of $E_+$ and $E_-$ are not symmetrical with respect to the energy level of $E_\text{1s}$.
Intuitive Explanation
The following is multiple choice question (with options) to answer.
What bonds form because they give atoms a more stable arrangement of electrons? | [
"covalent",
"Ionic bond",
"Polar bond",
"Hydrogen bond"
] | A | Covalent bonds form because they give atoms a more stable arrangement of electrons. Look at the hydrogen atoms in Figure above . Alone, each hydrogen atom has just one electron. By sharing electrons with another hydrogen atom, it has two electrons: its own and the one in the other hydrogen atom. The shared electrons are attracted to both hydrogen nuclei. This force of attraction holds the two atoms together as a molecule of hydrogen. |
SciQ | SciQ-3225 | c
Title: Match blood types in C I have written a solution to the blood-type matching problem, as described at https://projectlovelace.net/problems/blood-types/. The problem is to determine whether a given recipient (in this case, argv[1]) will find a match for a blood transfusion in an array of available donors (argv + 2).
Input blood type: B+
Input list of available blood types: A- B+ AB+ O+ B+ B-
Output: match
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <err.h>
typedef struct {
enum { O, A, B, AB } abo;
enum { P, M } rh;
} Blood;
const int abo[4][4] = {
{ O, O, O, O }, // O
{ O, A, O, A }, // A // *
{ O, B, O, B }, // B // *
{ O, A, B, AB }, // AB
};
const int rh[2][2] = {
{ P, M }, // P
{ M, M }, // M // *
};
Blood
parse(char *s){
char rh0 = s[strlen(s)-1];
char *abo0 = strdup(s);
abo0[strlen(s)-1] = '\0';
Blood b = {
!strncmp(abo0, "O", 1) ? O
: !strncmp(abo0, "A", 1) ? A
: !strncmp(abo0, "B", 1) ? B
: !strncmp(abo0, "AB", 2) ? AB
: -1,
rh0 == '+' ? P
: rh0 == '-' ? M
: -1,
};
return b;
}
The following is multiple choice question (with options) to answer.
What is the common abbreviation for noting the rhesus blood type? | [
"rh",
"RNA",
"AB",
"h2"
] | A | Rhesus blood type is determined by one common antigen. A person may either have the antigen (Rh + ) or lack the antigen (Rh - ). |
SciQ | SciQ-3226 | evolution, dna, theoretical-biology, genomes, species
Title: Biodiversity is restricted by genome combinatorics? Me and some friends are interested in opinions for the following:
Conjecture
The maximum number of species must be limited by the maximum
combinatorial/permutational space that can be occupied by DNA. Thus if
there is a maximum physical genome size this is what will determine
the maximum number of species that can possibly exist.
Explanation
E.G. say maximum number of DNA base pairs able to fit in a genome was $3$, each base pair can be one of either ${A,G,T,C}$. Then there are $4^3 = 64$ possible combinations of genomes. Extrapolate to genome sizes of $x$ base pairs, then there are $4^x$ combinations.
Questions
Would it be possible to claim that the underlying "blueprint" that codes for living diversity sets the absolute maximum for the total "diversity space"?
**Does it make sense to define the total number of species life can achieve with the simple function:
$S < 4^x$, where X is the maximum genome size measured in DNA base pairs?**
Notable Comments
The following is multiple choice question (with options) to answer.
Coral reefs are a type of what large community and have the highest biodiversity on earth? | [
"biome",
"taxon",
"phylum",
"order"
] | A | USFWS Pacific. Coral reefs are one of the biomes with the highest biodiversity on Earth . CC BY 2.0. |
SciQ | SciQ-3227 | cell-biology, neuroscience, histology
Although the paper mainly talks of the sorting of axonal and somatodendritic vesicles as seen in the picture, they also seem to apply for the RER which actually are the basis for Nissl's granules.
This structure excludes not only somatodendritic vesicles but also larger organelles, such as the Golgi complex and the rough ER, in effect constituting the cytoplasmic boundary for the somatodendritic and axonal domains..... The exclusion of the rough ER and Golgi complex, in addition to somatodendritic vesicles, at the PAEZ suggests that a common restriction mechanism may operate for all of these organelles.
Well, as you might have understood by now, it's not a matter of the size of the axon/ dendrite since same sized vesicles are being diverted in either direction and as previously mentioned, even mitochondria enter the axon.
The following is multiple choice question (with options) to answer.
What large organelle comprised of cup-shaped discs is found close to the nucleus of the cell, where it modifies proteins that have been delivered in transport vesicles? | [
"ribosome",
"mitochondria",
"golgi apparatus",
"chloroplast"
] | C | The Golgi apparatus is a large organelle that is usually made up of five to eight cup-shaped, membrane-covered discs called cisternae, as shown in Figure above . The cisternae look a bit like a stack of deflated balloons. The Golgi apparatus modifies, sorts, and packages different substances for secretion out of the cell, or for use within the cell. The Golgi apparatus is found close to the nucleus of the cell, where it modifies proteins that have been delivered in transport vesicles from the RER. It is also involved in the transport of lipids around the cell. Pieces of the Golgi membrane pinch off to form vesicles that transport molecules around the cell. The Golgi apparatus can be thought of as similar to a post office; it packages and labels "items" and then sends them to different parts of the cell. Both plant and animal cells have a Golgi apparatus. Plant cells can have up to several hundred Golgi stacks scattered throughout the cytoplasm. In plants, the Golgi apparatus contains enzymes that synthesize some of the cell wall polysaccharides. |
SciQ | SciQ-3228 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
The penis, testes and epididymes are structures in what male anatomical system? | [
"immune",
"protective",
"endocrine",
"reproductive"
] | D | The male reproductive system consists of structures that produce sperm and secrete testosterone. They include the penis, testes, and epididymes. |
SciQ | SciQ-3229 | optics, visible-light, electric-fields, reflection, refraction
Title: Brewster's angle reflected wave- is it part of the refracted or incident ray? I am trying to figure out what is happening to the charged particles in the reflective surface in the case of Brewster's angle. When this angle is different than zero or Brewster's angle, then the reflected light is only "partially" polarised. Why is the oscillation of the particles such that the reflected wave is polarized parallel to the reflecting surface when the angle is Brewster's angle?
I understand the explanation behind separating the electric fields into their components, yet I don't understand what causes this polarization to be observed? How does the vector component of the electric field emerge from the reflective surface while the other component remains as a part of the refracted wave?
By "parallel" I mean oscillating to the left and right- represented by dots (not into the page) in the diagram below. There are two planes I have talked about, the first one being the plane of the page(plane of incidence) and the plane perpendicular (the plane parallel to the reflecting surface, which is also the plane of polarization) An unpolarized wave can be represented by the sum of two waves with perpendicular polarisations and equal amplitude. The unpolarised incident wave can be considered to be of this nature, with one polarisation in the plane of incidence (p-polarised) and another at right angles to that (s-polarised), and with the electric fields of both being perpendicular to the direction of incident wave motion.
When the electric field of the incident wave is incident upon the interface, it sets up an electric field in the medium. Because of the continuity conditions for the electric field (any components tangential to the surface are continuous) and the requirement for a fixed phase relationship between the incident, reflected and transmitted waves, we obtain the law of reflection and Snell's law of refraction.
The following is multiple choice question (with options) to answer.
When waves are reflected at the same angle, what is it called? | [
"angle of reflection",
"field of view",
"refraction",
"phenomenon of reflection"
] | A | Reflected waves have the same speed and frequency as the original waves before they were reflected. However, the direction of the reflected waves is different. When waves strike an obstacle head on, the reflected waves bounce straight back in the direction they came from. When waves strike an obstacle at any other angle, they bounce back at the same angle but in a different direction. This is illustrated in the Figure below . In this diagram, waves strike a wall at an angle, called the angle of incidence. The waves are reflected at the same angle, called the angle of reflection, but in a different direction. Notice that both angles are measured relative to a line that is perpendicular to the wall. |
SciQ | SciQ-3230 | 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.
What us state leads all states in producing geothermal energy? | [
"nevada",
"Texas",
"california",
"virginia"
] | C | Geothermal energy is an excellent resource in some parts of the world. Iceland gets about one fourth of its electricity from geothermal sources. In the United States, California leads all states in producing geothermal energy. Geothermal energy in California is concentrated in the northern part of the state. The largest plant is in the Geysers Geothermal Resource Area. Geothermal energy is not economical everywhere. Many parts of the world do not have underground sources of heat that are close enough to the surface for building geothermal power plants. |
SciQ | SciQ-3231 | mycology, parasitology
Title: How do parasitic fungi sense optimal fruiting conditions from inside the host? Question is pretty straight forward. Are there generally any chemical cues? In model fungi, the G protein coupled receptor Gpr1 is known to sense sugars and upregulate a cAMP linked PKA pathway, while in pathogenic strains, it senses Methionine. This probably is the environmental cue that sets off fruiting. There is a recently published extensive review too: Heterotrimeric G protein signaling in filamentous fungi
Reference
Li, Liande, Sara J. Wright, Svetlana Krystofova, Gyungsoon Park, and Katherine A. Borkovich. “Heterotrimeric G Protein Signaling in Filamentous Fungi.” Annual Review of Microbiology 61, no. 1 (October 2007): 423–452.
The following is multiple choice question (with options) to answer.
Sexual signaling molecules released by fungi are known as what? | [
"hormones",
"vibrations",
"pheromones",
"sperm"
] | C | |
SciQ | SciQ-3232 | newtonian-mechanics, energy, everyday-life, biophysics
Running involves more and varied movements, it's a very different gait. It is definitely not just the same movement as walking but faster. Some of those movements are vertical, or relate to jumping, some have shock absorption components and relate to landing. Much of that extra energy is dissipated both ways - we use energy both to jump and to cushion and come to a halt on landing. We also accelerate our feet to match our ground speed and must slow them to zero each stride, then speed and lift the other way as well, not just rely on gravity and pendulum activity. The fact this is at extension and not at ground impact doesn't change anything. Again, energy is lost both ways. I'm also going to guess that it's harder to be efficient across a wider compared to narrower range of motions, therefore the wider range of movements and systems used in running means it's much more likely that efficiency varies considerably, according to biological subsystem or type of movement.
Human gross muscle motion energy handling/metabolism is not efficient and doesn't behave like an ideal object. We have multiple energy pathways, and switch between them according to need. This happens less with walking, more with vigorous exercise like running. The "emergency" or "sustained activity" energy cycle our bodies switch to, when running, is less efficient - if it was more efficient it would probably have evolved as our primary not our fallback. And of course many biochemical reactions and body responses just aren't linear; they also may have min/max rates or durations.
The following is multiple choice question (with options) to answer.
Which energy is momentarily stored in tendons after each leap provides a boost for the next leap? | [
"thermal",
"magnetic",
"kinetic",
"alternating"
] | C | |
SciQ | SciQ-3233 | body diagram of the situation. You can use the Inclined Plane – Simple Machine Gizmo™ to see how inclined planes can help to lift objects. An inclined plane of angle θ = 20. The inclined plane is one of the six classical simple machines defined by Renaissance scientists. A cylinder of mass m = 250 g and length l = 10 cm is placed on an inclined plane of a rake angle α = 30 °. Materials: spring scale, object: block of wood or similar object, flat board, string, masking tape, protractor. QUESTIONS: 1. A very important application in mechanics is the inclined plane. First draw a free body diagram of the block. Floating displays using a DCRA have the space efficiency problem of having a system thickness equal to the height of the floating image and the problem of a ghost image interrupting the visibility of the floating display. It allows one to use less force to move an object. A ramp is the most basic example of an inclined plane. The lecture begins with the application of Newton’s three laws, with the warning that they are not valid for objects that move at speeds comparable to the speed of light or objects that are incredibly small and of the atomic scale. 0-kilogram object accelerating at 10. In today's lab, you will be investigating how different angles of an inclined plane affect the easiness to pull up an object. Acceleration = m/s 2 compared to 9. A force of magnitude $$T=\text{312} \text{N}$$ up an incline is required to keep a body at rest on a frictionless inclined plane which makes an angle of $$\text{35}$$ $$\text{°}$$ with the horizontal. Compute The Component Of The Gravitational Force Acting Down The Inclined Plane. A body resting on a plane inclined at at an angle α to the horizontal plane is in a state of equilibrium when the gravitational force tending to slide the body down the inclined plane is balanced by an equal and opposite frictional force acting up the inclined plane. angle of inclination: The angle that the inclined surface makes with the horizontal ground. Get an answer for 'Work on an incline plane. Simple machines are tools that make your work easier. ) and Inclined Planes Overview. Most things would rapidly slide across a floor that was slanted almost vertically steep. Then, measure the distance from that point to the bottom of the plane. Lifting a load vertically straight up takes
The following is multiple choice question (with options) to answer.
What is the name for a simple machine that consists of two inclined planes? | [
"wedge",
"slope",
"pulley",
"lever"
] | A | Imagine trying to slice a tomato with a fork or spoon instead of a knife, like the one in Figure below . The knife makes the job a lot easier because of the wedge shape of the blade. A wedge is a simple machine that consists of two inclined planes. But unlike one inclined plane, a wedge works only when it moves. It has a thin end and thick end, and the thin end is forced into an object to cut or split it. The chisel in Figure below is another example of a wedge. |
SciQ | SciQ-3234 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
Each gamete will have one copy of each chromosome following which process involving cell division? | [
"genomes",
"osmosis",
"meiosis",
"mutations"
] | C | Figure 7.8 Following meiosis, each gamete has one copy of each chromosome. Nondisjunction occurs when homologous chromosomes (meiosis I) or sister chromatids (meiosis II) fail to separate during meiosis. |
SciQ | SciQ-3235 | human-evolution, skin
Title: Skin Colour in "Northern" Regions of The earth Question: Netflix has recently produced a two-part miniseries, The Evolution of US, that examines the evolution of "man". The topic of of human skin colour was covered and it was stated that 'lighter skin pigmentation was a preferred natural selection for early humans living in the "northern" regions'. The idea being that lighter skin could "absorb" sun-rays; which apparently is necessary for activating vitamin-D. Is this a true statement ? And where might I find good sources of literature to read on this topic ?
Now this particular series does not define "northern" and to be fair neither was the term "lighter skin" . My motivation in asking the question is driven by my own travels in far eastern Russia, Mongolia, Alaska, and parts of Peru and Ecuador. In each of those locations I observed numerous groups of indigenous people with dark brown skin and pitch black straight hair; which seems to contradict the statement in the series. Melanin reduces the skin's ability to make Vit D due to reduced UV penetration. This is a disadvantage in northern areas where people get less sun light, and also need to wear heavy cloths to keep warm which adds to the problem. People in Sunny regions have the opposite need as there is more than enough UV light exposure, but they run the risk of developing skin cancer, which is why having melanin provides an evolutionary advantage in these regions.
Interestingly, in the Arabian Gulf region, there is currently an epidemic of Vit D deficiency especially among those with dark skin. Although there is plenty of sun light, people tend to avoid the harsh sun almost completely by commuting strictly in cars and avoiding walking outdoors during the day. Car windows (and glass in general) are opaque to UV rays, therefor reducing the skin's ability to produce Vit D, and forcing many locals who adopt such lifestyle to take oral Vit D supplements.
Here is a link with some references to confirm the medical link between Vit D deficiency and lack of sunlight exposure:
https://www.webmd.com/food-recipes/qa/how-can-dark-skin-lead-to-vitamin-d-deficiency
The following is multiple choice question (with options) to answer.
Where do most skin structures originate in? | [
"dermis",
"epidermis",
"hypodermis",
"cuticle"
] | A | Layers of Human Skin. The outer layer of the skin is the epidermis, and the inner layer is the dermis. Most skin structures originate in the dermis. |
SciQ | SciQ-3236 | co2, ocean-models, carbon-capture
Title: Can phytoplankton growth be stimulated in oceans to sequester CO2? Casual learner only.
Decades ago, I read, one ocean scientist stated, jokingly, probably, "Give me half a shipload of iron filings and I will give you another ice age." This was in response to the fact of iron being the only deficit in the southern ocean holding back phytoplankton growth. Some experiments did take place since then revealing a danger of toxic blooms and that the iron did not stay long enough in the upper ocean to have significant effect. But I find no continued investigations into stimulating phytoplankton growth despite it being such a major source of carbon absorption. Research into the topic has been intermittent for a variety of reasons. Ocean iron fertilization experiments – past, present, and future looking to a future Korean Iron Fertilization Experiment in the Southern Ocean (KIFES) project reviewed the status of research on the topic in 2018 and recommended ways the concept could be tested.
The "iron hypothesis" put forth by John Martin in 1990 was that iron dust carried into the ocean accelerated historic ice ages by fertilizing phytoplankton which then captured enormous volumes of carbon dioxide, reducing the greenhouse effect -- iron being a key nutrient for phytoplankton. The suggestion followed that one could combat modern global warming by artificially fertilizing oceans with iron filings.
The KIFES paper linked above and other sources suggest no credible scientific organization has wanted to conduct the large-scale experimentation and risk the potential ecological impacts and public disapproval to test out whether iron fertilization will have the desired sequestration effects, though some startups such as Blue Dot Change plan to try on their own, according to MIT Technology Review.
The following is multiple choice question (with options) to answer.
What are the primary producers in the ocean? | [
"fish",
"zooplankton",
"phytoplankton",
"algea"
] | C | Phytoplankton are the primary producers in the ocean. They form the base of most marine food chains. |
SciQ | SciQ-3237 | organic-chemistry, bond, lewis-structure
Title: How do I draw a Lewis diagram after drawing the orbital diagram The question says "Oxygen can form compounds with every period 3 element except argon. Determine which would be ionic or covalent compounds, and draw Lewis diagrams to represent each one." I started with oxygen and fluorine and I'm having a hard time. I don't know if there should be lone pairs, double bonds, or even lone electrons.Here's my attempt at it: First of all, oxygen follows "the octet rule", which states that certain elements are stable when they have 8 electrons around them. Now this rule is by no means absolute, does not work with d orbitals onward, and should only be used in very elementary chemistry, unless you actually know its cause. In the case of that picture, you are missing 2 non-bonding electrons on the oxygen.
Remember that a covalent bond means that electrons are being shared by the 2 atoms. In the case of O and F, the pauling electronegativities are quite similar, so the electrons are actually "shared".
However, when you try to put oxygen together with group 1 or group 2 elements, you will find very different electronegativity values. What this means is that oxygen has much more affinity to electrons than Na or Mg. The rule I was taught at school was that a difference of 2 or more in electronegativity between the elements results in ionic compounds, meaning the oxygen "steals" the electrons, becoming a negative anion, whereas Na for example becomes a positive one.
The last guideline you should take into account, is that an atom tends to lose or gain electrons because it "likes" to have its most outer shell full. So when you look at the principal quantum number ($n$) of the most outer shell, you should create compounds where it is full. In the case of oxygen, that quantum number is $2$, which can have 8 electrons, hence the octet rule. For Na, you have 1 electron in $n=3$, so if the atom looses that electron, it will become more stable, therefore we have $\ce{Na+}$.
The following is multiple choice question (with options) to answer.
Chemists use simple diagrams to show an atom’s valence electrons and how they do what? | [
"bond",
"react",
"transfer",
"escape"
] | C | Lewis Diagrams Chemists use simple diagrams to show an atom’s valence electrons and how they transfer. These diagrams have two advantages over the electron shell diagrams introduced in Chapter 2 "Elements, Atoms, and the Periodic Table". First, they show only valence electrons. Second, instead of having a circle around the chemical symbol to represent the electron shell, they have up to eight dots around the symbol; each dot. |
SciQ | SciQ-3238 | soil-science
Title: How does humanure make soil "fluffier"? This BBC article says biosolids make soil "fluffier", among other benefits. How?
Adding humanure also changes soil structure, making it more resilient, preventing erosion and balancing out moisture, says Moss. It makes dirt fluffier, so water passes through easier. Conversely, in drought conditions, this also helps it retain water. The less compact soils are also softer, enabling seedlings to take faster and grow stronger roots, producing better yields. What are Biosolids and how do they work?
a biosolid is a product of the sewage treatment processes and is a semi-solid sludge of organic matter, nutrient-rich organic compounds. Here I list several reasons as to why biosolids would make the soil 'fluffier' and and better
As I said earlier biosolids are typically made out of organic matter, organic matter is carbon-based and biosolids are usually biological material (decomposed feces, urine and et cetera).
If you are not familiar with the normal decomposition processs it is a biological material (banana, apple, feces and et cetera) that is decomposed by microbes, molds, fungi and etc
biosolids are biological and/or organic material so what I just stated above applies to biosolids as well
Think of what you flush down a toilet or what goes down a sewer drain, are those things carbon based and biological? (human feces is an organic-compound and it goes in the sewers)
So now we know that biosolids are like other organic-compounds, how does this maker the soil fluffier. When something undergoes decomposition it turns into fresh brand-new soil, and quite obviously this new soil would be much more higher-quality and better than over-used old soil.
Here it states that organic material in a landfill produce gases due to decomposition so it makes sense that the same process would happen underground where microbial decomposition can release gases in the soil thus making the soil fluffier
So I can conclude that biosolids do, in fact help soil and make it fluffier and better.
The following is multiple choice question (with options) to answer.
Soil erosion is a natural process, but what can increase it unnaturally? | [
"human preservation",
"volcanic eruption",
"human activities",
"animal activies"
] | C | Soil erosion is a natural process, but human activities can increase it. |
SciQ | SciQ-3239 | biochemistry, physiology, cell-biology
Title: What triggers meiosis in gonadal cells? What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
What specific biochemical processes are involved in inducing meiosis rather than mitosis?
It's a difficult question because every step in the development of a germ cell is ultimately necessary for the final differentiation, which includes a meiotic division. Meiosis requires a lot of specialized components to pair and segregate homologues, to induce and resolve recombination, etc. What starts it all is still largely unknown. There are plenty of mutants that halt the process, but these are required along the way, so damaging the pathway ultimately stops it from progressing. At least one study has been able to initiate the program of meiosis in yeast:
Induction of meiosis in Saccharomyces cerevisiae depends on conversion of the transcriptional represssor Ume6 to a positive regulator by its regulated association with the transcriptional activator Ime1. I Rubin-Bejerano, S Mandel, K Robzyk, and Y Kassir
Basically, they turned on a transcription factor, which activated an entire suite of downstream genes necessary for meiosis. In essence, they turned on the "meiosis pathway." Bear in mind this is yeast, so does't have separate germ cells, but the concept is probably the same.
Why are gonadal cells the only cells in the human body which do undergo meiosis?
All other cells are diploid. Only in germ cells does the organism induce reductional divisions (to make haploid gametes for ultimate fusion in the zygote of the next generation). Creation of haploid somatic cells would uncover recessive lethal mutations and cells would die. In sperm and eggs, which do not express any genes until after fertilization and karyogamy, this is not a problem.
The following is multiple choice question (with options) to answer.
Which part of the reproductive process only contributes one set of chromosomes? | [
"ovum",
"plasma",
"egg",
"sperm"
] | D | This sperm is ready to penetrate the membrane of this egg. Notice the difference in size of the sperm and egg. Why is the egg so much larger? The egg contributes all the cytoplasm and organelles to the zygote. The sperm only contributes one set of chromosomes. |
SciQ | SciQ-3240 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
What do you call different organs working together? | [
"organ systems",
"endocrine system",
"maturation systems",
"cellular system"
] | A | |
SciQ | SciQ-3241 | classical-mechanics
Title: Help me find flaws on my simple machines invention I have a work to make an invention on simple machines. First of all I am sorry if my English is not very good or clear. As we all know, simple machines are used to simplify things in life and use less work (mechanical advantage). My concept is using a pulley to pull things up, but I want to use like a machine that needs to be stepped (lever type 3) to move the pulley. But I feel like there is a flaw to my invention, and feel very frustated. This is my concept visualization:
P.S: Sorry for the language usage (Image is semi-English and semi-Indonesian language)
Thank you for the help. The idea of simple machines is usually "sacrifice length to gain force". Or the opposite, but more rarely. You have incorporated a level and pulleys in your design. Let's analyze those.
The lever
The first problem is that you have made a lever that, if you step on it, the weight will go down. But, it would already go down by gravity, this is not useful. You probably want to counteract gravity and make it go up, so something like this:
The other problem is the general idea of using a level with your foot. The thing is, you can't move your foot much. This means do not really have length to sacrifice to gain force. So, to use a lever with your foot, you have to either:
Use it to lift something very light with a single motion of the foot. It's hard to find a use for this, though. Also, it means that the edge of the lever would be really long a take much space.
Use it to lift a heavy weight, but your foot won't have enough room. To gain multiple times one floor's height, you'd probably want to jump from some roof:
Now that we got the lever "solved", let's discuss the pulley (which is much easier for you to do without being unrealistic).
Note that just having a pulley somewhere doesn't provide you an advantage. You have to use something like a snatch block:
This will indeed allow you to use a long rope to raise the weight with less effort:
The following is multiple choice question (with options) to answer.
A machine is any device that makes work easier by doing what? | [
"changing molecules",
"removing barriers",
"moving things",
"changing a force"
] | D | A machine is any device that makes work easier by changing a force. When you use a machine, you apply force to the machine. This force is called the input force. The machine, in turn, applies force to an object. This force is called the output force. Recall that work equals force multiplied by distance:. |
SciQ | SciQ-3242 | experimental-physics, spectroscopy, gamma-rays
The issue I am having is with the photoelectric absorption and how light (optical photons are being generated) , the book I am ref from is 'Radiation Detection and Measurement, G.F Knoll, pg 49-50'. Also the crystal I am using for my experiment is a sodium/Thallium crystal.
So here my understand of how the photoelectric interaction is occurring in the crystal.
As the gamma photo enters the crystal it is 100% absorbed by an atom to which is comes into contact with and a photo electron is ejected, this is normally from the K-shell of the atom, so for my lab the gamma photo should have and energy > than the binding energy of the atom.
So when the photo electron is ejected a gap is left within the K-shell so a surrounding electron the fill it place and a characteristic x-ray is emitted and through phosphorylation and collisions with the photo electron optical light is generated by energy dissipation.
Is this along the correct line to what is actual happening within the crystal with regards to the photoelectric interaction. No. There are several steps involved. They all involve electrons and photons and atoms but with very different energies and numbers. Some accounts blur over the distinctions, but it's really quite clear.
First stage: a single high energy photon (gamma ray) interacts in the crystal. It may give all its energy to an atomic electron (photoelectric effect) or just some of it (Compton effect) or even, if its energy is large enough, have all its energy converted to an electron and a positron. So this electron (and maybe positron) has an energy of hundreds of keV. (The binding energy of the target electron is small on this scale).
Second stage: this electron (/positron) with its energy moves through the NaI crystal. It passes the crystal atoms and the field from its moving charge excites their atomic electrons to higher levels: as it does so it loses energy and slows down, eventually stopping. It travels a mm or so, which is a long way in terms of atoms, so it leaves lots of excited electrons behind it. These drop down to their original level and many of them give out photons as they do so which are in the visible region with typically eV energies.
The following is multiple choice question (with options) to answer.
When electricity is passed through solid sodium it changes into what and gives off light? | [
"gas",
"plasma",
"hydrocarbons",
"liquids"
] | A | A vapor light also produces visible light by electroluminescence The bulb contains a small amount of solid sodium or mercury as well as a mixture of neon and argon gases. When an electric current passes through the gases, it causes the solid sodium or mercury to change to a gas and emit visible light. Sodium vapor lights, like the streetlight pictured in the Figure below , produce yellowish light. Mercury vapor lights produce bluish light. In addition to lighting city streets, vapor lights are used to light highways and stadiums. The bulbs are very bright and long lasting so they are a good choice for these places. |
SciQ | SciQ-3243 | evolution, trees
Title: How related are trees? I was surprised to see how far apart macadamia and hazelnuts are from each other. I always thought all trees had a common ancestor that was also a tree. But that doesn't seem to be the case? Did wood evolve multiple times? The word "tree" is a not a taxonomic classification, but a human perceptual clustering based on form and size. The word "fish" has a similar problem, covering a vast collection of taxa, some of which are less closely related to one another than they are to us.
Becoming tree-like often has a strong evolutionary value, because plants compete for sunlight and taller plants shade shorter plants. Thus, we should not be surprised that "tree" forms have evolved independently in a number of different lineages.
The common evolutionary lineage for all of these, however, is tracheophyta, the vascular plants. These are plants that have differentiated xylem (which is the wood of a tree) and phloem tissues for transport of water and minerals. Most such plants are not trees, of course, but these tissues provide an effective means of vertical transport and the basis for hard woody material, which appears to have been the key differentiator between plants capable of evolving into trees and plants that are not able do to so.
The following is multiple choice question (with options) to answer.
What type of plant makes up nearly all plant species? | [
"angiosperms",
"microbes",
"fungus",
"gymnosperms"
] | A |
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