source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-44 | agriculture
The primary cereals for making bread are wheat and rye, while barley and oats may be mixed in. Historically significant portions of the rural population of Europe were sustained by cereal-based food in the form of gruel and porridge rather than by bread, especially prior to the introduction of the potato. Barley can be consumed in the form of pearl barley and groats and oats in the form of oatmeal. Especially in cool and humid climates not very suitable for cultivating wheat and rye, oats were once commonly cultivated and consumed. When Samuel Johnson wrote his dictionary, he famously defined oats as: "A grain which in England is generally given to horses, but in Scotland supports the people." A major historical and modern use of barley has been as malted barley, the main ingredient in beer brewing.
In the case of Finland it is interesting to note how late the transition from slash-and-burn agriculture to the use of permanent fields occurred. According to Teija Alenius, Environmental change and anthropogenic impact on lake sediments during the Holocene in the Finnish − Karelian inland area, Ph.D. thesis, University of Helsinki, 2007 (online)
The following is multiple choice question (with options) to answer.
Where does most of our food come from? | [
"gymnosperms",
"lichen",
"microbes",
"angiosperms"
] | D | |
SciQ | SciQ-45 | pressure, temperature, ideal-gas, states-of-matter
Title: Do gases have a general upper limit of density? Is there some limit for the density of gases, at which no change in condition could make it more dense without making it fluid, or solid - or something 'in between'? Yes - you can have a state where increasing the pressure would create a supercritical fluid
See Phase Diagram
The following is multiple choice question (with options) to answer.
Gases are most ideal at high temperature and what pressure? | [
"stable",
"high",
"absolute",
"low"
] | D | Under what conditions then, do gases behave least ideally? When a gas is put under high pressure, its molecules are forced closer together as the empty space between the particles is diminished. A decrease in the empty space means that the assumption that the volume of the particles themselves is negligible is less valid. When a gas is cooled, the decrease in kinetic energy of the particles causes them to slow down. If the particles are moving at slower speeds, the attractive forces between them are more prominent. Another way to view it is that continued cooling the gas will eventually turn it into a liquid and a liquid is certainly not an ideal gas anymore (see liquid nitrogen in the Figure below ). In summary, a real gas deviates most from an ideal gas at low temperatures and high pressures. Gases are most ideal at high temperature and low pressure. |
SciQ | SciQ-46 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
Hard igneous rocks and easily dissolved sedimentary rocks respond very differently to what natural force? | [
"weathering",
"sunlight",
"evaporation",
"gravity"
] | A | Each type of rock weathers in its own way. Certain types of rock are very resistant to weathering. Igneous rocks tend to weather slowly because they are hard. Water cannot easily penetrate them. Granite is a very stable igneous rock. Other types of rock are easily weathered because they dissolve easily in weak acids. Limestone is a sedimentary rock that dissolves easily. When softer rocks wear away, the more resistant rocks form ridges or hills. |
SciQ | SciQ-47 | human-biology, physiology, endocrinology, vitamins, homeostasis
Title: Counterintuitive action of Vitamin D? Vitamin D acts in a way which to me is counterintuitive. It functionally supplemets Parathormone. It in the intestinal tract steps up calcium absorption by altering nuclear gene expression and also prevents calcium excretion in kidneys. All of this is understandable. But it also, like parathormone, steps up osteoclast action in bone (actually steps up both osteoclast and osteoblast, but the osteoclast action is increased more to result in net bone resorption). This means that Vitamin D increases blood calcium level by increasing bone resorption.
Then how does Vitamin D help in improving bone density, bone strength and prevent rickets or osteoporosis? All of these would require bone deposition rather than resorption. There are two pieces to this question:
a) How does bone resorption (movement of Ca/Phos out of bone into the blood) result in net improvement in bone structure?
Bones are constantly remodeling, primarily in response to mechanical stressors. Although you clearly already realize this, I will make it explicit: osteoblasts are the cells that create new bone; osteoclasts break down (resorb) bone.
Quoting Harrison’s Internal Medicine1:
Radioisotope studies indicate that as much as 18% of the total skeletal calcium is deposited and removed each year. Thus, bone is an active metabolizing tissue.…The cycle of bone resorption and formation is a highly orchestrated process carried out by the basic multicellular unit, which is composed of a group of osteoclasts and osteoblasts
The following is multiple choice question (with options) to answer.
A diet rich in calcium and what vitamin may reduce the risk of osteoporosis and related bone fractures? | [
"vitamin A",
"vitamin d",
"niacin",
"vitamin C"
] | B | Skeletal system problems include osteoporosis, bone fractures, and ligament sprains. A diet rick in calcium and vitamin D may reduce the risk of osteoporosis and related bone fractures. Following safe practices may also reduce the risk of fractures as well as sprains. |
SciQ | SciQ-48 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
How many people die from air pollution each year? | [
"14 million",
"22 million",
"17 million",
"5 million"
] | B | Air pollution is harmful to human beings and other living things. About 22 million people die from air pollution each year. Breathing polluted air increases the risk of developing lung diseases such as asthma and lung cancer. Breathing bad air also increases the chances of dying from other diseases. Children are most likely to be affected by air pollution. That’s because their lungs are still developing and growing. Children also take in more air for their size than adults do. Some air pollutants damage the environment as well as the health of living things. The type of damage depends on the pollutant. Air pollution can also harm the environment. |
SciQ | SciQ-49 | microbiology, bacteriology, photosynthesis
2H+ + 2e– → H2
So that the overall reaction becomes:
2H2O + hν → 2H2 + O2
(Of course, this will be at the expense of energy and reducing power for carbohydrate synthesis.)
Using Hydrogenase for the Catalysis
The enzyme, hydrogenase, can catalyse the reduction of hydrogen ions shown above. This enzyme is rare in eukaryotes and absent from higher plants. It is thought to be very ancient, and may have originally been involved in energy generation from hydrogen in early evolution. One of the roles it plays in contemporary organisms is in reoxidizing NADH generated during certain fermentations in bacteria such as the Clostridium family — hydrogen is the gas produced in gas gangrene caused by Clostridium perfringens.
Certain photosynthetic organisms — notably the microalga, Chlamydomonas reinhardtii, and the photosynthetic cyanobacteria — also contain a hydrogenase in their chloroplasts. The activity of this is generally low, but appears to be coupled to photosynthesis in certain circumstances. This is through the reduced ferredoxin produced at PSI transferring its electron to the iron or iron–nickel centre of the hydrogenase:
The following is multiple choice question (with options) to answer.
What substances serve as catalysts in most of the biochemical reactions that take place in organisms? | [
"carbohydrates",
"hormones",
"iseotrops",
"enzymes"
] | D | Enzymes are involved in most of the biochemical reactions that take place in organisms. About 4,000 such reactions are known to be catalyzed by enzymes, but the number may be even higher. Enzymes allow reactions to occur at the rate necessary for life. |
SciQ | SciQ-50 | equilibrium
Title: metallic mercury is shaken with a solution of mercury(II) nitrate
Hi there, I am reviewing equilibrium.
About this question, I wonder if the chemical equation is wrong.
Because the description says 'a solution of mercury(I) nitrate is formed'.
However, in the equation, the product is Hg2 2+?
I thought the product should be Hg1+.
Here is my answer, but my answer seems to be wrong. Your expression would be correct if the mercury(I) ions were individual, separate atoms like most metals. But they are actually paired up, forming $\ce{Hg_2^{2+}}$ with a covalent bond between the metal atoms. Thus, properly,
$\ce{Hg(l) + Hg^{2+} <=> Hg2^{2+}}$
with $K_c$ then equalling $\ce{[Hg2^{2+}]/[Hg^{2+}]}$ as given in the textbook.
This behavior of forming diatomic metal(I) ions is actually known with several elements in Group 2 and Group 12 (or if you are using an older text, Group 2A and Group 2B), but mercury is the one that most commonly has metal(I) ions and not always metal(II). So your textbook (presumably) identifies specifically mercury as forming $\ce{Hg2^{2+}}$.
The following is multiple choice question (with options) to answer.
The formation of an amalgam allows the metal to react with what? | [
"air and water",
"cloth and plastic",
"helium and oxygen",
"blood and sweat"
] | A | The metals of group 13 (Al, Ga, In, and Tl) are all reactive. However, passivation occurs as a tough, hard, thin film of the metal oxide forms upon exposure to air. Disruption of this film may counter the passivation, allowing the metal to react. One way to disrupt the film is to expose the passivated metal to mercury. Some of the metal dissolves in the mercury to form an amalgam, which sheds the protective oxide layer to expose the metal to further reaction. The formation of an amalgam allows the metal to react with air and water. |
SciQ | SciQ-51 | homework-and-exercises, newtonian-mechanics, forces, friction, constrained-dynamics
Title: How can change in direction of force on pulley affect this situation This problem (the b part) asks me to find the acceleration of the blocks but I'm quite not able to understand 2 thing
1.how the change in direction of F will cause the change of acceleration.
How to judge whether kinetic or static friction is operating
I dont want the solution for it but the basic idea of how the change in this force can cause a change in equation
For the determination of friction the general way to us is to assume that they move together then find common acceleration and again putting this acceleration in an equation to check whether friction coming out is greater than or less than static friction but here net force on system is upwards so:
my equations
For $m_1$
$F$-$f_s$=$m_1a$
For $m_2$
$T$+$f_s$=$m_2 a$ This answer is for (b) part.
Finding whether static or kinetic friction will be involved is easy.
We can see that pulling up results in the lower mass $m_2$ moving backwards and $m_1$ moving forwards. So the masses are surely going to slip.
Only reason to not slip would be if $F < \mu_s m_1 g$ which does not seem to be the case.
The reason why direction of $F$ matters can be understood if we consider (just for understanding) that the friction between $m_1$ and $m_2$ is so high that they don't slip. Then in case (1), the string would not even move and it would be equivalent to pulling $m_1 + m_2$ with a force $F$ horizontally. In case (2), If we imagine the blocks to not slip as previous, then F is basically trying to lift the system up and we won't have horizontal acceleration. Hope you understood why direction matters.
The reaction force on pulley1 would be different in both cases and since that pulley is attached to the mass itself, it makes a difference. ie: in case(2) $F_2$ would be along $X$ and that would also contribute to Acceleration.
The following is multiple choice question (with options) to answer.
A pulley changes the direction of the force t exerted by the cord without changing its what? | [
"magnitude",
"latitude",
"longitude",
"position"
] | A | automobile axle drives a wheel, which has a much larger diameter than the axle. The MA is less than 1. (c) An ordinary pulley is used to lift a heavy load. The pulley changes the direction of the force T exerted by the cord without changing its magnitude. Hence, this machine has an MA of 1. |
SciQ | SciQ-52 | biochemistry, bacteriology
Title: What is the film that covers the tongue? What is the film that covers the tongue in the mornings, even after brushing the teeth and tongue the night before and why does it have color variations? Do the different colors mean anything? It isn't really a film. The tiny bumps that cover your tongue are called papillae, and are normally pink in color. However, they can become inflamed and white when irritated. The appearance of the white "coating" is caused by debris, bacteria and dead cells getting lodged between the papillae.
You may be breathing through your mouth when you sleep, which is drying it out. Bacteria may also still be the cause; you may not be brushing well enough or your toothpaste may not be correctly doing its job.
The color variations may be due to different types or amounts of debris, or the color may vary with different conditions listed here. Tongue color changes also often occur with glossitis (inflammation of the tongue itself).
The following is multiple choice question (with options) to answer.
What is the name of the small bumps that contain taste buds and covers the tongue? | [
"palatine tonsils",
"lingual tonsils",
"cuticle",
"papillae"
] | D | Figure 14.3 The Tongue The tongue is covered with small bumps, called papillae, which contain taste buds that are sensitive to chemicals in ingested food or drink. Different types of papillae are found in different regions of the tongue. The taste buds contain specialized gustatory receptor cells that respond to chemical stimuli dissolved in the saliva. These receptor cells activate sensory neurons that are part of the facial and glossopharyngeal nerves. LM × 1600. (Micrograph provided by the Regents of University of Michigan Medical School © 2012). |
SciQ | SciQ-53 | forces, newtonian-gravity, acceleration, collision, free-fall
Title: Gravity and force I have a question and am not able to answer it.
Suppose you drop two objects from different heights. They are exactly the same shape, size and weight. Now we know that the gravitational acceleration is constant for all objects. Also, $F = ma$. Since both the values are the same, they ought to exert the same force on Earth on striking which is not true. You may imagine the difference between someone dropping a ball on you from a feet and one from 10 feet. Can you explain the reason?
And what exactly is force? Is it the strength for the smallest time or for a second?
If we apply Newton's second law to my question, then the ball dropped from a height should remain in contact in the ground for a very short time and bounce off quickly?
Since both the values are the same, they ought to exert the same force on Earth on striking which is not true.
Actually, the values are not the same. The gravitational acceleration is equal for them both, but the acceleration in $\sum F=ma$ is not this gravitational acceleration.
When something hits the ground, it is stopped. That is, it is slowed down very fast from it's impact speed to no speed. That is, it experiences a very large deceleration. And it is this acceleration, you plug into the $\sum F=ma$ formula.
Now, surely, the object with higher impact speed, which is the object that falls from the largest height, is decelerated more and therefore experiences a much larger force on impact, to cause this deceleration.
The following is multiple choice question (with options) to answer.
In the absence of air resistance, all falling objects accelerate at the same rate due to what force? | [
"motion",
"gravity",
"weight",
"velocity"
] | B | What if you were to drop a bowling ball and a soccer ball at the same time from the same distance above the ground? The bowling ball has greater mass than the basketball, so the pull of gravity on it is greater. Would it fall to the ground faster? No, the bowling ball and basketball would reach the ground at the same time. The reason? The more massive bowling ball is also harder to move because of its greater mass, so it ends up moving at the same acceleration as the soccer ball. This is true of all falling objects. They all accelerate at the same rate due to gravity, unless air resistance affects one object more than another. For example, a falling leaf is slowed down by air resistance more than a falling acorn because of the leaf’s greater surface area. You can simulate the effect of air resistance on acceleration due to gravity by doing the interactive animation at this URL: http://www. science-animations. com/support-files/freefall. swf. |
SciQ | SciQ-54 | molecular-biology, cell-biology, proteins, cell-membrane
Title: What is meant by "opposing plasma membrane" with respect to cell adhesion molecules? I am reading the Handbook of Neurochemistry and Molecular Neurobiology and I am learning about cell adhesion molecules (CAMs) and I have come across the following:
CAMs are involved in homo‐ or heterophilic interactions with molecules
positioned on opposing plasma membranes, and such interactions are
referred to as trans‐interactions. In addition, CAMs are often
involved in homo‐ or heterophilic interactions with other
membrane‐associated molecules positioned in the same plasma membrane.
Such membrane‐lateral interactions are referred to as
cis‐interactions.
I know that cell adhesion molecules are proteins mediation cell-cell or cell-extracellular matrix interactions. However, in the above excerpt from the book in the following statement: CAMs are involved in homo‐ or heterophilic interactions with molecules positioned on opposing plasma membranes, I am not sure what exactly is meant by "opposing plasma membranes". I think that this refers to the plasma membrane of a neighbouring cell the CAM is interacting with, however I am not fully certain.
Any insights are appreciated. Opposing means facing each other, so the two outer surfaces can interact. Like two opposing armies.
I found an article:
"Pharmacology of cell adhesion molecules of the nervous system"
at
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2644493/
doi: 10.2174/157015907782793658
"...CAM-induced intracellular signalling is triggered via homophilic (CAM-CAM) and heterophilic (CAM - other counter-receptors) interactions..."
The following is multiple choice question (with options) to answer.
The ability for a plasma membrane to only allow certain molecules in or out of the cell is referred to as what? | [
"total permeability",
"moderate permeability",
"periodic permeability",
"selective permeability"
] | D | The plasma membrane forms a barrier between the cytoplasm inside the cell and the environment outside the cell. It protects and supports the cell and also controls everything that enters and leaves the cell. It allows only certain substances to pass through, while keeping others in or out. The ability to allow only certain molecules in or out of the cell is referred to as selective permeability or semipermeability. To understand how the plasma membrane controls what crosses into or out of the cell, you need to know its composition. |
SciQ | SciQ-55 | 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.
In the presence of oxygen, hydrogen can interact to make what? | [
"water",
"carbon",
"acid",
"helium"
] | A | A pile of leaves slowly rots in the backyard. In the presence of oxygen, hydrogen can interact to make water. Gold can be stretched into very thin wires. |
SciQ | SciQ-56 | galaxy
Title: How many galaxies have been discovered? I know Andromeda is our nearest galaxy. But how many known galaxies have been discovered and what are they? First, the nearest galaxy to ours is not Andromeda, according to the NASA based page "The Nearest Galaxies", it was until recently considered to be the Canis Major Dwarf Galaxy at approximately 42,000 light years away. However, recently, there is suggestion that the closer Omega Centauri Globular Cluster may be a disrupted dwarf galaxy (Another source).
Now, in answer to your other query of how many galaxies there are - there is a global project called Galaxy Zoo which is attempting to catalogue and classify all observed galaxies, so far, according to the Galaxy Zoo for astronomers page, thus far they have
the entire Sloan Digital Sky Survey spectroscopic sample and all existing Hubble Space Telescope surveys (around 1.5 million galaxies in total).
Pictured: The Hubble Ultra-Deep Field which contains over 10,000 objects, the majority of which are galaxies. The image is only a bit over 3 arcminutes across--a tiny sliver of the sky.
The following is multiple choice question (with options) to answer.
What galaxy is our solar system a part of? | [
"milky way",
"Andromeda",
"Bode's Galaxy",
"Centaurus"
] | A | Compared to Earth, the solar system is a big place. But galaxies are bigger - a lot bigger. A galaxy is a very large group of stars held together by gravity. How enormous a galaxy is and how many stars it contains are impossible for us to really understand. A galaxy contains up to a few billion stars! Our solar system is in the Milky Way Galaxy. It is so large that if our solar system were the size of your fist, the galaxy’s disk would be wider than the entire United States! There are several different types of galaxies, and there are billions of galaxies in the universe. |
SciQ | SciQ-57 | electrical-engineering
The rod of diameter d is bent around a curve of radius r. The light beam is tangent to the inner edge at B, and strikes the outer edge at angle t - so it stays in, but only just. Angle OBA is between a radius and a tangent, so is a right angle.
We can then express t using some trigonometry as
sin(t) = r/(r+d)
Serendipity! we already know sin(t) in terms of refractive indices, so we can write:
n1/n2 = r/(r+d)
And re-arrange for r:
r = d/(n2/n1 -1)
If we use the refractive index of air (n1=1) and acrylic (n2=1.49) then this simplifies to
r > 2.04d
Now, there may be slight variations in refractive index for different acrylic grades, and for different wavelengths, so you'll probably want to keep to a bend radius a bit larger than that, but it should give a good starting point.
The following is multiple choice question (with options) to answer.
The angle at which light bends when it enters a different medium is known as what? | [
"resonance",
"bounce",
"refraction",
"frequency"
] | C | The angle at which light bends when it enters a different medium depends on its change in speed. The greater the change in speed, the greater the angle of refraction is. For example, light refracts more when it passes from air to diamond than it does when it passes from air to water. That’s because the speed of light is slower in diamond than it is in water. |
SciQ | SciQ-58 | 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.
Whether the organism is a bacterium, plant, or animal, all living things access energy by breaking down these? | [
"carbohydrate molecules",
"oxygen molecules",
"protein molecules",
"lipid molecules"
] | A | The Energy Cycle Whether the organism is a bacterium, plant, or animal, all living things access energy by breaking down carbohydrate molecules. But if plants make carbohydrate molecules, why would they need to break them down, especially when it has been shown that the gas organisms release as a “waste product” (CO2) acts as a substrate for the formation of more food in photosynthesis? Remember, living things need energy to perform life functions. In addition, an organism can either make its own food or eat another organism—either way, the food still needs to be broken down. Finally, in the process of breaking down food, called cellular respiration, heterotrophs release needed energy and produce “waste” in the form of CO2 gas. In nature, there is no such thing as waste. Every single atom of matter and energy is conserved, recycling over and over infinitely. Substances change form or move from one type of molecule to another, but their constituent atoms never disappear (Figure 8.20). CO2 is no more a form of waste than oxygen is wasteful to photosynthesis. Both are byproducts of reactions that move on to other reactions. Photosynthesis absorbs light energy to build carbohydrates in chloroplasts, and aerobic cellular respiration releases energy by using oxygen to metabolize carbohydrates in the cytoplasm and mitochondria. Both processes use electron transport chains to capture the energy necessary to drive other reactions. These two powerhouse processes, photosynthesis and cellular respiration, function in biological, cyclical harmony to allow organisms to access life-sustaining energy that originates millions of miles away in a burning star humans call the sun. |
SciQ | SciQ-59 | thermodynamics, rotational-kinematics, degrees-of-freedom
$$ B \approx 3.97 \times 10^{-23} \text{J} $$
which is about $3k$. So as long as the temperature is above say $30K$ the rotational modes will be excited and nitrogen will have a specific heat of $\tfrac{5}{2}R$. If you go down to temperatures of $3K$ and below then the specific heat will fall to $\tfrac{3}{2}R$ just like a monatomic gas.
The specific heat of nitrogen at constant volume is 0.743 kJ/(kg.K), and converting this to J/mole.K we get 20.8 J/(mole.K) and this is indeed 2.50R (to three significant figures).
The conformist mentions that the vibrations of the nitrogen molecule will contribute to the specific heat, and indeed they will. However the energy of the first vibrational mode is 2359 cm$^{-1}$, which converted to non-spectrogeek units is $4.7 \times 10^{-20}$ J or about $3400k$. So the vibrational mode isn't going to contribute to the specific heat until the temperature gets above 3400K.
The following is multiple choice question (with options) to answer.
Increasing the temperature of n2 molecules increases what energy of motion? | [
"compression energy",
"emotional energy",
"residual energy",
"kinetic energy"
] | D | Increasing the temperature increases the average kinetic energy of the N2molecules. |
SciQ | SciQ-60 | electromagnetic-radiation
Here is something you can do for fun and might be instructive too. Get a small portable AM radio and tune it between stations. Now move it around near your computer when the computer is running. You will hear all kinds of strange noises. The noises might even change somewhat depending on what the computer is doing. Now go do the same thing to other electronic devices. If you think the computer was noisy, try holding the radio near your refigerator when its running, near your fuse box, or near your car with the hood up. There is a lot of low power RF floating around, with disk drives being very very tiny sources in the scheme of things.
The following is multiple choice question (with options) to answer.
Which radio frequency should you listen to if you want less noise? | [
"wave",
"fm",
"am",
"cb"
] | B | FM radio is inherently less subject to noise from stray radio sources than AM radio. The reason is that amplitudes of waves add. So an AM receiver would interpret noise added onto the amplitude of its carrier wave as part of the information. An FM receiver can be made to reject amplitudes other than that of the basic carrier wave and only look for variations in frequency. It is thus easier to reject noise from FM, since noise produces a variation in amplitude. Television is also broadcast on electromagnetic waves. Since the waves must carry a great deal of visual as well as audio information, each channel requires a larger range of frequencies than simple radio transmission. TV channels utilize frequencies in the range of 54 to 88 MHz and 174 to 222 MHz. (The entire FM radio band lies between channels 88 MHz and 174 MHz. ) These TV channels are called VHF (for very high frequency). Other channels called UHF (for ultra high frequency) utilize an even higher frequency range of 470 to 1000 MHz. The TV video signal is AM, while the TV audio is FM. Note that these frequencies are those of free transmission with the user utilizing an old-fashioned roof antenna. Satellite dishes and cable transmission of TV occurs at significantly higher frequencies and is rapidly evolving with the use of the high-definition or HD format. |
SciQ | SciQ-61 | astrophysics, radiation, thermal-radiation, plasma-physics
Title: Is Sun brighter than what we actually see? I learned from that plasma can reflect radiations of frequency less than that of its own oscillations. If so, considering the plasma in Sun's atmosphere, it should also reflect solar radiations.
That would mean that the radiation emitted from the inner layers of the Sun would be reflected back by the outer layers. So, the only radiation coming out should be the ones generated at the outer layers, for which there is no denser layers of plasma surrounding it. And of course, the ones that have higher frequencies than the plasma in each layer would come out unscathed.
If this is true, most of the radiation generated by fusion will be trapped inside, and what we observe is only a fraction.
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer. So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties? Is Sun brighter and hotter than what we see from outside?
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer.
Because the material in the star is opaque, it completely depends on the outermost layer. Of course the properties of that layer (such as its temperature) are driven by the energy coming from the interior.
So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties?
It is appropriate for an object that has a spectrum that closely matches a blackbody spectrum. However the only property that describes is the temperature of the visible layer. It doesn't imply anything about the interior and processes that produce and distribute energy. You shouldn't read blackbody and think that means that the (invisible) interior is simple or in some way similar to the exterior.
The sun's interior is much hotter than the exterior (around 15 million Kelvin in the core, compared to the 6000 Kelvin or so at the photosphere). Because it is not visible, I would hesitate to call it "brighter". But you could consider it that way.
The following is multiple choice question (with options) to answer.
What form of radiation is the energy emitted by the sun? | [
"magnetic",
"seismic",
"electromagnetic",
"thermal"
] | C | Figure 8.11 The sun emits energy in the form of electromagnetic radiation. This radiation exists at different wavelengths, each of which has its own characteristic energy. All electromagnetic radiation, including visible light, is characterized by its wavelength. |
SciQ | SciQ-62 | astrophysics, radiation, thermal-radiation, plasma-physics
Title: Is Sun brighter than what we actually see? I learned from that plasma can reflect radiations of frequency less than that of its own oscillations. If so, considering the plasma in Sun's atmosphere, it should also reflect solar radiations.
That would mean that the radiation emitted from the inner layers of the Sun would be reflected back by the outer layers. So, the only radiation coming out should be the ones generated at the outer layers, for which there is no denser layers of plasma surrounding it. And of course, the ones that have higher frequencies than the plasma in each layer would come out unscathed.
If this is true, most of the radiation generated by fusion will be trapped inside, and what we observe is only a fraction.
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer. So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties? Is Sun brighter and hotter than what we see from outside?
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer.
Because the material in the star is opaque, it completely depends on the outermost layer. Of course the properties of that layer (such as its temperature) are driven by the energy coming from the interior.
So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties?
It is appropriate for an object that has a spectrum that closely matches a blackbody spectrum. However the only property that describes is the temperature of the visible layer. It doesn't imply anything about the interior and processes that produce and distribute energy. You shouldn't read blackbody and think that means that the (invisible) interior is simple or in some way similar to the exterior.
The sun's interior is much hotter than the exterior (around 15 million Kelvin in the core, compared to the 6000 Kelvin or so at the photosphere). Because it is not visible, I would hesitate to call it "brighter". But you could consider it that way.
The following is multiple choice question (with options) to answer.
What is the suns innermost layer called? | [
"surface",
"flare",
"solar",
"core"
] | D | The core is the Sun's innermost layer. The core is plasma. It has a temperature of around 15 million degrees Celsius (C). Nuclear fusion reactions create the immense temperature. In these reactions, hydrogen atoms fuse to form helium. This releases vast amounts of energy. The energy moves towards the outer layers of the Sun. Energy from the Sun's core powers most of the solar system. |
SciQ | SciQ-63 | human-biology, endocrinology, growth
Title: Pituitary giants - is the fusing of growth plates dependent on amount of growth hormone in blood? I wanted to ask a couple questions related to pituitary giants (people who are giants because of some anomaly, such as a tumor, in their pituitary gland).
Some of these giants seem to keep growing and growing until the tumor (or the gland) is removed. Is this because the fusing of the growth plates is controlled by the amount of growth hormone in blood?
The reason for this question is that many of the giants have been described to grow past when the growth plates should probably have fused. For example (all heights in meter, m):
Bernard Coyne This giant is described as having been 2.36m at the age of 20, but 2.54m at the time of his death at the age of 23.
Edouard Beaupré At the age of 17, this giant was measured as 2.16m tall and at the age of 21, he was measured at 2.50m tall. At the time of his death, at the age of 23, he was listed (in his death certificate) as having been 2.51m tall and "still growing".
Väinö Myllyrinne This giant was 2.22m at the age of 21 but is described as having "experienced a second phase of growth in his late thirties", attaining a height of 2.51m by the time of his death at 54.
Adam Rainer This giant was, unusually enough, a "dwarf" at the age of 18, reaching a height of 1.22m. However he had a growth spurt afterwards, reaching a height of 2.18m at the age of 30 and 2.34m by the time of his death at age 49.
The following is multiple choice question (with options) to answer.
A growth spurt requires constant divisions of what? | [
"seeds",
"proteins",
"hairs",
"cells"
] | D | To grow and develop, you must form new cells. Imagine how often your cells must divide during a growth spurt. Growing just an inch requires countless cell divisions. Your body must produce new bone cells, new skin cells, new cells in your blood vessels and so on. |
SciQ | SciQ-64 | 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's the term for the gradual progression from simple plants to larger more complex ones in an area? | [
"complex progression",
"primary pattern",
"pattern progression",
"primary succession"
] | D | The pioneer species is soon replaced by other populations. Abiotic factors such as soil quality, water, and climate will determine the species that continue the process of succession. Mosses and grasses will be able to grow in the newly created soil. During early succession, plant species like grasses that grow and reproduce quickly will take over the landscape. Over time, these plants improve the soil and a few shrubs can begin to grow. Slowly, the shrubs are replaced by small trees. Small trees then are succeeded by larger trees. Since trees are more successful at competing for resources than shrubs and grasses, a forest may be the end result of primary succession. |
SciQ | SciQ-65 | species-identification, botany, ecology
Title: Algae or Lichen identification. Coastal BC, Canada I have tried all books and internet resources I know of, but I still have no idea what this might be — a lichen or something else.
At first glimpse, I thought it was something man-made and unnatural, but then I looked closer and saw how it appears to be attached and growing. It grows on exposed rocks well above the high tide. The photo is taken in late March, on northern Vancouver Island. It's loosely attached to the rock.
It was somewhat abundant around the general area (within of a few km), but I haven't seen it elsewhere - although I'm not from BC so there might be a lot of this around.
The water droplet in the lower right corner give a rough sense of scale.
Edit:
Adding another photo in which I just noticed a streak of white, which I included in original resolution. I want to propose you expand your search to a broader taxonomic scope. Specifically, I think you might be looking at a species of "red" green algae (family: Trentepohliaceae).
From Nelson et al. (2011):
All Trentepohliaceae have filamentous growth forms and often contain large amounts of carotenoid pigments (ß-carotene and hematochrome), causing the algae to appear yellow orange in color (Thompson and Wujek 1997, Lo´pez-Bautista et al. 2002).
The Trentepohliaceae contains five genera: (Trentepohlia, Printzina, Phycopeltis, Cephaleuros and Stomatochroon) and 70+ species worldwide.
For example, the following algae (picture from England) looks fairly similar to your specimen:
Trentepohlia aurea
Source: David Fenwick
If your specimen is a species in this family of algae, it is most likely in the Trentepohlia genus (or possibly Printzina genus).
Trentepohlia is a genus of filamentous chlorophyte green algae in the family Trentepohliaceae.
Typically orange or yellow in color.
Live on tree trunks and wet rocks or symbiotically in lichens.
Here's a picture of a free-living Trentepohlia species from coastal Oregon, USA:
Source: Richard C. Hoyer (2015)
The following is multiple choice question (with options) to answer.
Fungi may form mutualistic relationships with plants, algae, cyanobacteria, and what? | [
"plants",
"eggs",
"farmers",
"animals"
] | D | |
SciQ | SciQ-66 | nitrogen
Step three is when plants and the animals that live of the plants die and breaks down into ammonia and other waste products (this is where many explanations of the nitrogen cycle usually starts). The waste products gets converted into ammonia by bacteria and the ammonia gets converted to nitrite and the entire cycle starts all over again.
Legumes have a symbiotic relationship with some bacteria that can fixate nitrogen (N2) https://aces.nmsu.edu/pubs/_a/A129/
sources:
https://science.howstuffworks.com/life/biology-fields/nitrogen-cycle.htm
https://www.britannica.com/science/denitrifying-bacteria
The rest is from my memory.
The following is multiple choice question (with options) to answer.
Which cycle tracks the flow of nitrogen through an ecosystem? | [
"life cycle",
"nitrogen reaction",
"nitrogen cycle",
"water cycle"
] | C | Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation. The nitrogen cycle tracks the flow of nitrogen through an ecosystem . CC BY-NC 3.0. |
SciQ | SciQ-67 | meteorology, weather-forecasting, tornado, thunderstorm
Title: Could a large burst of super-heated or super-cooled air cause tornadoes to fall apart? We know how tornadoes form: when areas of hot air and cold air mingle, causing rotation. We can even see them form on the radar.
Yet, for all of our technology, we can't stop such events from happening - even though we can cause it to rain by seeding clouds.
But if someone were at the area that a tornado was about to form and was able to introduce an area of super-heated or super-cooled air into the potential tornado, would it destabilize the formation of the destructive whirlwind? Or would doing such a thing cause more of them to form or for them to form more quickly and/ or be more damaging? Changing air currents is very difficult and energy intensive. You'd need to alter an entire weather system - no easy feat. If you heated a very large region of cool air you might prevent the spiraling that causes tornadoes to form, but you'd need to warm at least few states worth of upper atmosphere. It would be an enormous undertaking.
There's also the logistical problem of how would you go about doing it? Heating in principal can be done faster than cooling, presumably sending up a whole lot of hydrogen in a few hundred balloons and igniting it forming hot water-vapor, which as it condenses, would further heat the atmosphere. Cooling warm air is harder as there's no quick and easy method to cool an enormous volume of air, so I think heating the high cold air would be easier than cooling the low moist air, but it would still be an enormous effort and probably cost more in prevention than the tornadoes are likely to do in total damage.
http://images.slideplayer.com/22/6379142/slides/slide_22.jpg
There's no neat and tidy technological trick to get it done that I can think of.
The following is multiple choice question (with options) to answer.
What consequence of a tornado is responsible for most injuries and deaths? | [
"falling debris",
"catching debris",
"flying debris",
"touring debris"
] | C | A tornado only strikes a small area. But it can destroy everything in its path. Most injuries and deaths from tornadoes are caused by flying debris ( Figure below ). In the United States, an average of 90 people are killed by tornadoes each year. The most violent two percent of tornadoes account for 70% of the deaths by tornadoes. |
SciQ | SciQ-68 | 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 are the only truly innate behaviors in humans called? | [
"reflexes",
"automatic movements",
"feats",
"flinches"
] | A | All animals have innate behaviors, even human beings. Can you think of human behaviors that do not have to be learned? Chances are, you will have a hard time thinking of any. The only truly innate behaviors in humans are called reflex behaviors . They occur mainly in babies. Like innate behaviors in other animals, reflex behaviors in human babies may help them survive. |
SciQ | SciQ-69 | thermodynamics, pressure, atmospheric-science, density, air
Title: Why does air pressure decrease with altitude? I am looking to find the reason: why air pressure decreases with altitude? Has it to do with the fact that gravitational force is less at higher altitude due to the greater distance between the masses? Does earth’s spin cause a centrifugal force? Are the molecules at higher altitude pushing onto the molecules of air at lower altitudes thus increasing their pressure? Is the earths air pressure higher at the poles than at the equator? The air pressure at a given point is the weight of the column of air directly above that point, as explained here. As altitude increases, this column becomes smaller, so it has less weight. Thus, points at higher altitude have lower pressure.
While gravitational force does decrease with altitude, for everyday purposes (staying near the surface of the Earth), the difference is not very large. Likewise, the centrifugal force also does not have significant impact.
The following is multiple choice question (with options) to answer.
What happens to the density of air as the altitude decreases? | [
"remains the same",
"increases",
"multiplies",
"decreases"
] | D | The pressure of the earth’s atmosphere, as with any fluid, increases with the height of the column of air. In the case of earth’s atmosphere, there are some complications. The density of the air is not uniform but decreases with altitude. Additionally there is no distinct top surface from which height can be measured. We can, however, calculate the approximate difference in pressure between two altitudes using the equation . The average pressure of the atmosphere at sea level is 1.013 × 10 5 Pa. This pressure is often expressed as 101.3 kPa. |
SciQ | SciQ-70 | general-biology, habitat
Title: How does life change when you dig deeper? I've just realized that I have no idea what life / biotopes / soil looks like when you dig deeper than a few meters.
I know that in the first meter of soil you can find all sorts of live animals (like moles and rabbits), insects (like ants, but many more), plants, and single-celled organisms, of course.
But how does that change when you get to the depth of a metro station (below 30m)? When you plan to build a metro, do you have to consider that you might destroy a biotope?
I guess there is a point from which you will quite certainly not find animal/plant life in the soil anymore. This will, of course, depend on where exactly you are. But can you give a rough estimate of how deep we're talking? 50m? 100m? 1km? Extremophile bacteria and archea are living very deep beyond our imaginations. This is what you need for general composition at different depths. And this and this is for the deepest living organism known ! Following is image from (Manson et al 2010) which shows at what depth you will get bacteria
Even more deeper, Wold's single species ecosystem, Desulforudis audaxviator which can be found 3 km below sea level.
The following is multiple choice question (with options) to answer.
How do some animals change their depth? | [
"by changing their density",
"metamorphosis",
"mass migration",
"spontaneous mutations"
] | A | Some animals change their depth by changing their density. Recall that things that are denser than their surroundings sink while those that are less dense than their surroundings float. Most fish have a swim bladder, a special sac that is filled with gases from their blood. When the fish's swim bladder is full, it is less dense than the surrounding water and the fish will rise towards the surface. Another property of water that affects lakes is the unique changes in density during phase changes. The density of most substances increases when a liquid becomes a solid. This is not so for water: Solid water is actually less dense than liquid water. It is for this reason that ice floats. Can you imagine a world where ice sank? Lakes would freeze from the bottom up, killing many fish. Frozen water in the Polar Regions would sink and change the ocean levels. The fact that ice floats is essential for the survival of many aquatic ecosystems and ultimately life on Earth. Besides the changes in density, there are other ways in which the phase changes of water have significant impacts. When water is trapped in small cracks in rocks, it will expand as it freezes and break up the rock causing weathering. The transpiration (evaporation) of water from a good-sized tree can move 1800 liters of water out of the ground in a single day. Sublimation, the phase change between solid and gas, is responsible for the formation of frost. As you can see, water has many special properties that make its role in nature unique. It is considered the "universal solvent” because its bipolar molecule enables it to dissolve a wide variety of substances. Water is the only substance that occurs naturally in all three states; solid, liquid, and gas. Water is truly a miracle for life!. |
SciQ | SciQ-71 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
What phenomenon is crowding out other species and making all the other causes of extinction worse? | [
"human overpopulation",
"climate change",
"human suburbanization",
"migration"
] | A | Human overpopulation, which is crowding out other species. It also makes all the other causes of extinction worse. |
SciQ | SciQ-72 | human-biology, toxicology
Effect on biological systems (Wikipedia)
Kushner DJ, Baker A, Dunstall TG. Pharmacological uses and perspectives of heavy water and deuterated compounds. Can J Physiol Pharmacol. 1999 Feb;77(2):79-88. PMID: 10535697.
Steve Scheiner and Martin Čuma. Relative Stability of Hydrogen and Deuterium Bonds. J. Am. Chem. Soc. 1996 118, 6, 1511–1521 DOI: 10.1021/ja9530376
*Experiments with mice, rats, and dogs have shown that a degree of 25% deuteration causes (sometimes irreversible) sterility, because neither gametes nor zygotes can develop. Mammals (e.g. rats) were given heavy water to drink die after a week, at a time when their body water approaches about 50% deuteration. The mode of death appears to be the same as that in cytotoxic poisoning or in acute radiation syndrome , and is due to deuterium's action in generally inhibiting cell division.
The following is multiple choice question (with options) to answer.
Dessication is an extreme and usually fatal form of what in animals? | [
"depletion",
"dehydration",
"starvation",
"diarrhea"
] | B | |
SciQ | SciQ-73 | diffusion
Incidentally, this derivation can also be presented in terms of particles at dynamical equilibrium in a gravitational field (again under the assumption that the system is isothermal) or in terms of osmotic pressure. For some discussion of the different versions, see the Wikipedia page on Brownian motion.
The following is multiple choice question (with options) to answer.
Internal and external forms of what life process occur as simple diffusion due to a partial pressure gradient? | [
"photosynthesis",
"respiration",
"metabolism",
"reproduction"
] | B | Internal Respiration Internal respiration is gas exchange that occurs at the level of body tissues (Figure 22.23). Similar to external respiration, internal respiration also occurs as simple diffusion due to a partial pressure gradient. However, the partial pressure gradients are opposite of those present at the respiratory membrane. The partial pressure of oxygen in tissues is low, about 40 mm Hg, because oxygen is continuously used for cellular respiration. In contrast, the partial pressure of oxygen in the blood is about 100 mm Hg. This creates a pressure gradient that causes oxygen to dissociate from hemoglobin, diffuse out of the blood, cross the interstitial space, and enter the tissue. Hemoglobin that has little oxygen bound to it loses much of its brightness, so that blood returning to the heart is more burgundy in color. Considering that cellular respiration continuously produces carbon dioxide, the partial pressure of carbon dioxide is lower in the blood than it is in the tissue, causing carbon dioxide to diffuse out of the tissue, cross the interstitial fluid, and enter the blood. It is then carried back to the lungs either bound to hemoglobin, dissolved in plasma, or in a converted form. By the time blood returns to the heart, the partial pressure of oxygen has returned to about 40 mm Hg, and the partial pressure. |
SciQ | SciQ-74 | evolution, species
Title: Reasons why living fossils exist?
A living fossil is a living species (or clade) that
appears to be similar to another species otherwise known only from fossils,
typically with no close living relatives.
A living fossil is considered as a successful organism, which has made its way through many major extinction events. Also, the morphology of living fossils resemble some species of organisms which we know only through their fossil remains.
What is the reason for a particular type of species to become a living fossil; is the engineering of this particular species extraordinary, in that it can survive any selection process encountered thus far?
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Have these organisms modified themselves, so that currently their morphology seems to be similar to a fossil organism? One part of your question betrays a serious error:
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Actually the reverse is true; constancy of form can only be maintained in the presence of continuous selective pressure. It's just that this is stabilising selection that acts to maintain the existing form rather than push the organism to new morphologies. In fact, most selection acts in this manner. This shouldn't surprise you: organisms are typically well adapted to their environments so changes are more likely to reduce fitness than increase fitness.
It's also worth noting that although living fossils show little morphological change they can continue to show change at the molecular level at rates as high as, or higher than, other organisms - e.g. (May et al 2007; Cao et al 2013).
The following is multiple choice question (with options) to answer.
The fossil record shows that this type of event is followed by the evolution of new species to fill the habitats where old species lived? | [
"mass extinction",
"formation extinction",
"minor extinction",
"moderate extinction"
] | A | After each mass extinction, new species evolve to fill the habitats where old species lived. This is well documented in the fossil record. |
SciQ | SciQ-75 | soil
Caliche generally forms when minerals leach from the upper layer of the soil (the A horizon) and accumulate in the next layer (the B horizon), at depths around 3 to 10 feet under the surface. It generally consists of carbonates in semiarid regions—in arid regions, less-soluble minerals form caliche layers after all the carbonates have been leached from the soil. The deposited calcium carbonate accumulates—first forming grains, then small clumps, then a discernible layer, and finally, a thicker, solid bed. As the caliche layer forms, the layer gradually becomes deeper, and eventually moves into the parent material, which lies under the upper soil horizons.
However, caliche also forms in other ways. It can form when water rises through capillary action. In an arid region, rainwater sinks into the ground very quickly. Later, as the surface dries out, the water below the surface rises, carrying up dissolved minerals from lower layers. This water movement forms a caliche that tends to grow thinner and branch out as it nears the surface. Plants can contribute to the formation of caliche, as well. Plant roots take up water through transpiration, and leave behind the dissolved calcium carbonate, which precipitates to form caliche. It can also form on outcrops of porous rocks or in rock fissures where water is trapped and evaporates. In general, caliche deposition is a slow process, but if enough moisture is present in an otherwise arid site, it can accumulate fast enough to block a drain pipe.
(photo from http://www.naturephoto-cz.com/karst-cave-photo-24442.html)
The following is multiple choice question (with options) to answer.
Soluble minerals and clays accumulate in what soil layer, allowing it to hold more water? | [
"subsurface",
"subsoil",
"topsoil",
"silt"
] | B | Below the topsoil is the “B” horizon. This is also called the subsoil . Soluble minerals and clays accumulate in the subsoil. Because it has less organic material, this layer is lighter brown in color than topsoil. It also holds more water due to the presence of iron and clay. There is less organic material in this layer. |
SciQ | SciQ-76 | electric-circuits, potential, electrical-resistance, conductors
These analogies are not exact and are only intended to give you a better feel as to what is happening.
Hope this helps.
The following is multiple choice question (with options) to answer.
What is the common word for potential difference in a circuit? | [
"frequency",
"velocity",
"watt",
"voltage"
] | D | Conceptual Questions 19.1 Electric Potential Energy: Potential Difference 1. Voltage is the common word for potential difference. Which term is more descriptive, voltage or potential difference? 2. If the voltage between two points is zero, can a test charge be moved between them with zero net work being done? Can this necessarily be done without exerting a force? Explain. What is the relationship between voltage and energy? More precisely, what is the relationship between potential difference and electric potential energy? 4. Voltages are always measured between two points. Why? 5. How are units of volts and electron volts related? How do they differ?. |
SciQ | SciQ-77 | zoology, phylogenetics, literature, palaeontology
Title: Size of Purussaurus, a giant Miocene crocodylian (2022) What is the currently accepted size estimates (length and mass) of Purussurus barsiliensis? I quote the relevant part in Wikipedia.
From Wikipedia: https://en.wikipedia.org/wiki/Purussaurus
The skull length of the largest known individual of the type species, P. brasiliensis is 1,453 millimetres (57.2 in).[2] It has been estimated that P. brasiliensis reached about 10.3 metres (34 ft) in length, weighing about 5.16 metric tons (5.69 short tons).[2] Another estimate gave a larger size of 12.5 metres (41 ft) in length, ranging from 9.8–15.7 metres (32–52 ft), and 8 metric tons (8.8 short tons) in weight, ranging from 5.6–12.6 metric tons (6.2–13.9 short tons), with a mean daily food intake of 40.6 kilograms (90 lb).[3] It is also likely that Purussaurus reached only 10.9 metres (36 ft) long and 5.6 metric tons (6.2 short tons).[3] A 2022 study estimated a length of 7.6–9.2 metres (25–30 ft) and a mass of 2–6.2 metric tons (2.2–6.8 short tons) using a phylogenetic approach; and a length of 9.2–10 metres (30–33 ft) and mass of 3.9–4.9 metric tons (4.3–5.4 short tons) using a non-phylogenetic approach.[4]
Old estimates were up to 13 meters but more recent ones decreased it to 10.9 and the newest one from 2022 decreased even further:
A 2022 study estimated a length of 7.6–9.2 metres (25–30 ft) and a mass of 2–6.2 metric tons (2.2–6.8 short tons) using a phylogenetic approach; and a length of 9.2–10 metres (30–33 ft) and mass of 3.9–4.9 metric tons (4.3–5.4 short tons) using a non-phylogenetic approach.[4]
The following is multiple choice question (with options) to answer.
How many chambers does the stomach of a crocodile have? | [
"three",
"ten",
"six",
"two"
] | D | The crocodilian digestive system is highly adapted to their lifestyle. Crocodilians are known to swallow stones, known as gastroliths , which help digest their prey. The crocodilian stomach is divided into two chambers. The first is powerful and muscular. The other stomach is the most acidic digestive system of any animal. It can digest mostly everything from their prey, including bones, feathers, and horns!. |
SciQ | SciQ-78 | mathematical-models, population-dynamics
Title: Range of feasible coefficients in an unlimited growth model If you are given an unlimited growth model in the form:
$\frac {dP(t)}{dt} = k P(t)$
Obviously the population growth would never be unlimited, but let's presume for the moment that we are introducing a species into an environment where there is the possibility for unlimited growth, at least on for a given time -- i.e. invasive species.
$k$ is some rate of growth of the population at time $t$, denoted by $P(t)$
What are some feasible values of $k$? In other words, if a number is way above or way below $k$, where would I know that the research I am reading is preposterously off-base?
I am sure it is different for different types of animals, including mammals, birds, bacteria, etc. A solid limit: k must be greater than zero. Unless you're talking about some cannibalistic species or something that isn't suited to the model at all.
As long as the species is productive in the new environment: k is greater than 1. The population is probably growing or again you probably won't be using an exponential growth model.
As mentioned before you would need to know the species for more information. But if you look at generation times and litter sizes:
Some bacterial generation times (from here) range from 10 to
2000 minutes (33 hours). So that is $k=2$ per generation time. Per
day you're looking at a lower bound of 2 per day and an upper bound
of $k=2^{14}=10^{43}$ per day.
Mice are something like 12 week generation time and a litter of 10
giving something like $k=10^{10}$ per year.
Elephants are one young every 25 years. So $k=16$ per century or so.
Of course this is all based on gross assumptions. But you're looking for guidelines for a unrealistic model so hopefully they'll do.
The following is multiple choice question (with options) to answer.
When populations get close to the carrying capacity, what happens to growth? | [
"spikes",
"dies",
"slows",
"halts"
] | C | Populations usually grow bigger when they have what they need. How fast they grow depends on birth and death rates. They grow more slowly as they get close to the carrying capacity. This is the biggest population the environment can support. |
SciQ | SciQ-79 | heat, thermal-conductivity
Title: Why would a ~1 cm thick layer of argon be a significantly poorer conductor of heat than air? In yesterday's new Periodic Video, Argon (new) - Periodic Table of Videos, after about 07 min 00 sec, Sir Martyn Poliakoff says:
The final, and I have to admit perhaps slightly boring application of argon, is in double glazing (of windows) to keep our houses warm. Because argon has a heavy atom, the atoms don’t move very fast in the gas phase, and therefore they’re bad at conducting heat (emphasis added).
So if you have double glazing (that’s two sheets of glass in your window) if you put argon between the glass, it is much more effective at insulating the inside of the house, keeping cold out, than if you use air, because air has a much higher conductivity of heat.
So, if you look out of the window, you may find that you are looking through argon gas.
The following is multiple choice question (with options) to answer.
Although air can transfer heat rapidly by convection, it is a poor conductor and thus a good what? | [
"transporter",
"absorber",
"insulator",
"magnet"
] | C | Although air can transfer heat rapidly by convection, it is a poor conductor and thus a good insulator. The amount of available space for airflow determines whether air acts as an insulator or conductor. The space between the inside and outside walls of a house, for example, is about 9 cm (3.5 in) —large enough for convection to work effectively. The addition of wall insulation prevents airflow, so heat loss (or gain) is decreased. Similarly, the gap between the two panes of a double-paned window is about 1 cm, which prevents convection and takes advantage of air’s low conductivity to prevent greater loss. Fur, fiber, and fiberglass also take advantage of the low conductivity of air by trapping it in spaces too small to support convection, as shown in the figure. Fur and feathers are lightweight and thus ideal for the protection of animals. |
SciQ | SciQ-80 | botany, plant-physiology, plant-anatomy
Title: How do plants grow year after year even though they die? How do plants grow, die, and then grow again? For instance, when my plants die during the winter, how do they grow again next year? Does it have something to do with the root system? Or do they even die? It depends on the type of plant, but basically not all of the plant dies. Plants have evolved a number of strategies for winter* dormancy. These are common ones, but probably not an exhaustive list.
Deciduous trees and bushes simply drop their leaves in the fall, and so may look "dead" to the unskilled eye - though with practice, it's usually easy to distinguish between dead and dormant. Then when the weather warms in the spring, new leaves grow.
Other perennial plants may lose some or all of their top growth, even dying back to ground level, but the roots will be alive, and will start growing when the ground warms.
Still other plants have developed specialized underground structures like bulbs & rhizomes - think daffodils, tulips, irises, and similar. The rest of the plant dies, only to grow again from the bulb when conditions are right.
It's worth noting that most, if not all, of these are used for propagation as well, often naturally, and frequently with a bit of human help. Bulbs and rhizomes multiply: the daffodil bulb you planted a few years ago may now be a dozen bulbs, each of which can be moved to grow new ones. Many perennials can be increased by dividing the root mass into pieces, each of which will become a new plant. And cuttings from many trees & bushes can be induced to form new root systems, and become new plants.
Or summer, dry season, &c. For simplicity, I'll just say "winter".
The following is multiple choice question (with options) to answer.
Most plants grow continuously, except for what periods? | [
"winter",
"abnormal",
"mutant",
"dormant"
] | D | |
SciQ | SciQ-81 | the-moon, telescope, hubble-telescope
Title: Powerful-enough telescopes to observe the Lunar Roving Vehicle from Earth? Apparently, not even the Hubble telescope (which is actually in orbit, not even on Earth) is powerful enough to observe the LVR... will we ever have the technology to observe the LVR from Earth?
(it would be my dream to be able to observe the Apollo relics with a "retail" telescope. I am no expert in optics, so have no idea if for example "computer-enhanced" zooming could work, instead of a giant mirror?) I don't think so. In order to resolve an object one metre across (as a single pixel) at a distance of 384,400km (the diameter of the Moon's orbit), you would need a telescope mirror about 200 metres in diameter, and to achieve a resolution of 10cm (which you would probably need to form a recognisable image), you would need a telescope mirror with a 2km diameter. Currently the largest Earth based telescope has a 30-metre mirror.
The following is multiple choice question (with options) to answer.
What man-made devices in space are used to observe the earth's surface? | [
"crystals",
"telescopes",
"sensors",
"satellites"
] | D | Observations can happen on many scales. You can use a microscope to observe tiny things. You can use a telescope to observe distant things in space. To learn about the effects of climate change, you could observe Earth's surface. How would you make observations of Earth's surface? You could do this from the land surface or from space. Many important observations are made by orbiting satellites. These satellites have a bird's eye view of how the planet is changing ( Figure below ). |
SciQ | SciQ-82 | acid-base, equilibrium, ph, electronic-configuration
Covalent compounds of elements in the third period and below tend to be very weak bases, if at all. I'm not sure why, but I suspect that it's because bonds involving these elements tend to form much weaker dipoles than bonds involving nitrogen. The weaker dipole would limit their ability to forcibly pull protons off of water molecules.
All that said, there are many ionic compounds that form basic solutions due to containing the cation of a weak acid. In these cases the base is a cation, not a molecule. Certainly some of these cations contain nitrogen, but many do not. Examples without nitrogen include any soluble carbonates and bicarbonates and any salts of carboxylic acids.
The following is multiple choice question (with options) to answer.
Carboxylic acids are weak acids, meaning they are not 100% ionized in what? | [
"liquid",
"air",
"water",
"ethanol"
] | C | Carboxylic acids are weak acids (see the chapter on acids and bases), meaning they are not 100% ionized in water. Generally only about 1% of the molecules of a carboxylic acid dissolved in water are ionized at any given time. The remaining molecules are undissociated in solution. We prepare carboxylic acids by the oxidation of aldehydes or alcohols whose –OH functional group is located on the carbon atom at the end of the chain of carbon atoms in the alcohol:. |
SciQ | SciQ-83 | endocrinology
Title: Abnormal Prolactin Level I want to know what makes the balance of the Prolactin abnormal. Is that related to the presence of a nodule near the pituitary? The main abnormality in prolactin levels is hyperprolactinemia, meaning blood levels of prolactin above the normal range, not during pregnancy or lactation.
The major cause of these abnormal prolactin levels are tumors consisting of pituitary lactotroph cells--called prolactinomas--which secrete prolactin. This is generally corrected with synthetic dopamine analogues, as dopamine negatively regulates secretion of prolactin in lactotroph cells.
Here is a 2010 review with further detail:
http://joe.endocrinology-journals.org/content/206/1/1.full.pdf
The following is multiple choice question (with options) to answer.
An endocrine disease usually involves the secretion of too much or not enough of what? | [
"sweat",
"metabolite",
"hormone",
"enzyme"
] | C | Diseases of the endocrine system are relatively common. An endocrine disease usually involves the secretion of too much or not enough hormone. When too much hormone is secreted, it is called hypersecretion. When not enough hormone is secreted, it is called hyposecretion. |
SciQ | SciQ-84 | genetics
Title: Can there be medium height(neither tall nor short) pea plants in Mendel's experiment? Can there be medium height(neither tall nor short) pea plants in Mendel's experiment?
All textbooks I have read seem to imply that pea plants have to be either tall or short, nothing in between. Medium height (like in people) and other traits that seem like a mixture of two extremes are often a result of incomplete dominance. For example, a red and white flower are bred to produce an offspring with pink petals.
Mendelian genetics does not include incomplete dominance (which is classified as, surprisingly, non-Mendelian genetics).
Basically, Mendel got very lucky with his choice of plant. Pea plant height is strictly dominant, meaning one dominant allele results in tall plants, regardless of the identity of the second inherited allele. This is a consequence of the genetic makeup of pea plants. Had he tried a similar experiment with snapdragon flower color, he would be very confused.
(See https://www.ndsu.edu/pubweb/~mcclean/plsc431/mendel/mendel2.htm for snapdragon incomplete dominance example.)
The following is multiple choice question (with options) to answer.
In experiments with garden peas, austrian monk gregor mendel described the basic patterns of what? | [
"inheritance",
"preference",
"color",
"behavior"
] | A | For thousands of years, humans have understood that characteristics such as eye color, hair color, or even flower color are passed from one generation to the next. The passing of characteristics from parent to offspring is called heredity . Humans have long been interested in understanding heredity. Many hereditary mechanisms were developed by scholars but were not properly tested or quantified. The scientific study of genetics did not begin until the late 19 th century. In experiments with garden peas, Austrian monk Gregor Mendel described the basic patterns of inheritance. Keep in mind that while we know about DNA and its role as the genetic material, Mendel did not know of the existence of DNA. Nor did he understand the concept of the chromosome or the process of meiosis, and yet, he was still able to correctly describe basic inheritance patterns. |
SciQ | SciQ-85 | physiology, nutrition, organic-chemistry
Title: How is it known that there are only three macronutrients: proteins carbohydrates and lipids? It is stated here that in human nutrition, micronutrients are nutrients required generally in less than 100 mg daily quantities whereas macronutrients are required in gram quantities. It is widely stated that our macronutrients are carbohydrates, lipids, and proteins. How was it shown that these are the human macronutrients and that we don't have other macronutrients?
One answer to this similar question on Quora suggests that ethanol or ketones could be considered macronutrients. Ethanol is mentioned in this article, though ketones are not. Other sources I saw didn't clarify. Summary
The question is based on the misconception that the term “macronutrient” originated as a scientific definition, to which entities satisfying this definition were assigned. In fact it was a default term used as a distinction from compounds falling into the earlier category, “micronutrient”, and was used initially to encompass the three specific classes of food that had been established to be sources of energy through decades of nutritional research. Hence there was no question of whether there “should” be more macronutrients. The term is not a scientific definition, and today is used in different ways so that anyone using the term needs to clarify what it should be taken to mean in that particular context.
Food Energy and the history of Nutrition
Scientific studies of nutrition, dating the late 18th century, were initially concerned with chemical structure, metabolic fate and energy produced by different foods, and this is described in a short readable article by Ned Stafford in Nature (2010) 468, S16–17.
By the end of the 19th century protein, fat and carbohydrate had been established as the chemical fuels that supplied energy from the diet, and the energy values (in terms of the, now obsolete, calorie) had been established by Atwood, using his respiration calorimeter.
Micronutrients
The following is multiple choice question (with options) to answer.
Nutrition and diet affect your metabolism. more energy is required to break down fats and proteins than this? | [
"vitamins",
"carbohydrates",
"electrolytes",
"minerals"
] | B | 24.7 Nutrition and Diet Nutrition and diet affect your metabolism. More energy is required to break down fats and proteins than carbohydrates; however, all excess calories that are ingested will be stored as fat in the body. On average, a person requires 1500 to 2000 calories for normal daily activity, although routine exercise will increase that amount. If you ingest more than that, the remainder is stored for later use. Conversely, if you ingest less than that, the energy stores in your body will be depleted. Both the quantity and quality of the food you eat affect your metabolism and can affect your overall health. Eating too much or too little can result in serious medical conditions, including cardiovascular disease, cancer, and diabetes. Vitamins and minerals are essential parts of the diet. They are needed for the proper function of metabolic pathways in the body. Vitamins are not stored in the body, so they must be obtained from the diet or synthesized from precursors available in the diet. Minerals are also obtained from the diet, but they are also stored, primarily in skeletal tissues. |
SciQ | SciQ-86 | organic-chemistry, nomenclature, hydrocarbons
Title: Preferred IUPAC names for branched unsaturated hydrocarbons (polyenes)?
What are the preferred IUPAC names for the following three compounds?
Compound 1 is 3-ethenylhexa-1,5-diene. 2 is 3-methylidenehexa-1,5-diene.
But I am still not sure about 3. I have narrowed it down to two choices: 3-ethylidenehexa-1,5-diene or 4-ethenylhexa-1,4-diene.
How do I decide which two of the three double bonds should be in the parent chain, considering that both choices of parent chain have the same number of complex and double bonds?
The information I used is from the following Q&As:
How is a side-group that contains a double bond named?
How do you name an alkene using IUPAC rules if the longest carbon chain in this alkene does not include the double bond? According to the general methodology described in the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), a double bond is expressed by changing the ending ‘ane’ of the name of the corresponding saturated parent structure to ‘ene’.
P-31.1.1.1 The presence of one or more double or triple bonds in an otherwise saturated parent hydride (…) is denoted by changing the ending ‘ane’ of the name of a saturated parent hydride to ‘ene’ or ‘yne’. Locants as low as possible are given to multiple bonds as a set, even though this may at times give ‘yne’ endings lower locants than ‘ene’ endings. If a choice remains, preference for low locants is given to the double bonds. In names, the ending ‘ene’ always precedes ‘yne’, with elision of the final letter ‘e’ in ‘ene’. Only the lower locant for a multiple bond is cited, except when the numerical difference between the two locants is greater than one, in which case the higher locant is enclosed in parentheses.
(…)
For example:
The following is multiple choice question (with options) to answer.
What are unsaturated hydrocarbons with at least one double bond between carbon atoms called? | [
"peptides",
"alkenes",
"amines",
"enzymes"
] | B | Alkenes are unsaturated hydrocarbons with at least one double bond between carbon atoms. |
SciQ | SciQ-87 | solvents, solubility, melting-point, phase
Similarities:
In each case, forces between the particles that comprise the solid are disrupted and that takes energy. (Whether it’s chemical bonds or intermolecular forces depends on the process and on the solid and on your definitions. (See this question.) But melting (rare exception noted in previous comments) is endothermic and dissolving can be either endo- or exo-thermic.
In each case you end up with a liquid. Macroscopically, if you walked into a room and saw the liquid on the table, it would be difficult to say whether this liquid came from a solid that had melted or a solid that had dissolved in a solute and made a solution.
But it would be very easy to determine which you had experimentally in a “dozen” different ways.
Both melting and dissolving require interaction among groups of atoms, molecules, or ions.
There are probably more differences that could be given (how to handle thermodynamic calculations, complexity of the system etc.), and possibly more similarities, but that's enough for me on this topic.
The following is multiple choice question (with options) to answer.
What is the opposite of melting? | [
"freezing",
"liquidation",
"compression",
"evaporation"
] | A | All of the changes of state that occur between solid, liquid and gas are summarized in the diagram in the figure below. Freezing is the opposite of melting and both represent the equilibrium between the solid and liquid states. Evaporation occurs when a liquid turns to a gas. Condensation is the opposite of vaporization and both represent the equilibrium between the liquid and gas states. Deposition is the opposite of sublimation and both represent the equilibrium between the solid and gas states. |
SciQ | SciQ-88 | sensation, olfaction
http://www.comeaddestrareuncane.com/blog/tag/cani-molecolari/
In the dog, the surface of the olfactory mucosa varies between 70 and 150 cm2 - in this tissue the number of olfactory receptors varies from 250 to 280 million - In 1962, Becker et al. showed that dogs are able to recognize substances in dilutions from 1/100 to 1/10.000.000.
- http://milano.corriere.it/milano/notizie/cronaca/12_febbraio_19/cani-olfatto-parere-esperto-1903358352720.shtml
Have you noticed how a dog sniffs the urine of a female "tasting it"? It is the same action that makes the viper when it follows the track of the mouse: it evertes the tongue and carries on it the odorous particles in the buccal cavity, and this organ has a function in the middle between the olfactory and gustatory ones. "Pointing dogs" is as pointing "the wild" taste the smell.
"Eat the scent", in the jargon, because savored, not only in terms of smell, the smell of the wild. The Jacobson's organ is then a second organ capable of perceiving odors, the first we've said is represented ciliated epithelium of the mucous membrane of the nose.
But there is a third organ called the "Rodolfo-Masera" which also serves to sense the emanations chemical (not yet known which), that way you could explain a specialization of these organs to perceive certain groups of biochemicals than others.
- http://www.laciotola.net/Cani/la-funzione-olfattiva-del-cane.html
The following is multiple choice question (with options) to answer.
A unique characteristic of mammals is the ability to chew, this happens by the temporalis and the masseter allowing what? | [
"Bakward and forward",
"Up and down",
"side-to-side movement",
"Grinding"
] | C | The adductor muscle that closes the jaw is composed of two muscles in mammals: the temporalis and the masseter. These allow side-to-side movement of the jaw, making chewing possible, which is unique to mammals. Most mammals have heterodont teeth, meaning that they have different types and shapes of teeth rather than just one type and shape of tooth. Most mammals are diphyodonts, meaning that they have two sets of teeth in their lifetime: deciduous or “baby” teeth, and permanent teeth. Other vertebrates are polyphyodonts, that is, their teeth are replaced throughout their entire life. Mammals, like birds, possess a four-chambered heart. Mammals also have a specialized group of cardiac fibers located in the walls of their right atrium called the sinoatrial node, or pacemaker, which determines the rate at which the heart beats. Mammalian erythrocytes (red blood cells) do not have nuclei, whereas the erythrocytes of other vertebrates are nucleated. The kidneys of mammals have a portion of the nephron called the loop of Henle or nephritic loop, which allows mammals to produce urine with a high concentration of solutes, higher than that of the blood. Mammals lack a renal portal system, which is a system of veins that moves blood from the hind or lower limbs and region of the tail to the kidneys. Renal portal systems are present in all other vertebrates except jawless fishes. A urinary bladder is present in all mammals. Mammalian brains have certain characteristics that differ from other vertebrates. In some, but not all mammals, the cerebral cortex, the outermost part of the cerebrum, is highly folded, allowing for a greater surface area than is possible with a smooth cortex. The optic lobes, located in the midbrain, are divided into two parts in mammals, whereas other vertebrates. |
SciQ | SciQ-89 | pathology
Title: Why are some bodily fluids more of an infection risk than others? Whilst on a recent refresher course it was highlighted that when considering risk of exposure to infection from bodily fluids we should be aware of two distinct risk levels:
High Risk:
Blood
Semen
Vaginal Secretions
Diarrhea
Low Risk:
Saliva
Vomit
Urine
CSF (Cerebrospinal fluid)
Why is it that some bodily fluids are a greater infection risk than others? Is it related to the fluids themselves or the species of pathogen that are located within them? This is just about where the pathogens can be found that are dangerous to people.
Vomit is highly acidic and less accommodating to microbe growth. Similarly saliva has many immune components in it as well as digestive enzymes that keep most microorganisms down.
Urine and CSF are actually quite sterile as they come from environments that are highly filtered - the kidney is an osmotic processor that essentially is a molecular filter and does not allow cells to pass, the spine is highly insulated from the blood and other direct exposure to microorganisms.
Compare that with the 'dangerous' list and you have organs that are open to human pathogens. Venerial disease like HPV is so common that what - about 1 in 5 people under a certain age carry it. That is a pretty high expectation of a biohazard. most infections and viruses are blood bourne - influenza, cold, as well as any bacterial infections.
Feces is always a dangerous thing to handle as the digestive tract is rich in nutrients and essentially directly open to external bacteria and fungi. (and its not acidified like the stomach). Also parasites like tape worms and other multicelled animals! yum!
Diarrhea is often caused by an infection of some sort, so its just more likely a hazard, but feces is always a place where you might find a pathogen.
This is not to say that the 'safe' list is totally safe. Its just less likely to bear disease causing agents.
The following is multiple choice question (with options) to answer.
Most of the pathogens that cause stis enter the body through mucous membranes of which organs? | [
"reproductive organs",
"eyes",
"stomach",
"kidneys"
] | A | Most of the pathogens that cause STIs enter the body through mucous membranes of the reproductive organs. All sexual behaviors that involve contact between mucous membranes put a person at risk for infection. This includes vaginal, anal, and oral sexual behaviors. Many STIs can also be transmitted through body fluids such as blood, semen, and breast milk. Therefore, behaviors such as sharing injection or tattoo needles is another way these STIs can spread. |
SciQ | SciQ-90 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
The activation of what kind of buds induces branching? | [
"leafy buds",
"arterial buds",
"lymphatic buds",
"axillary buds"
] | D | |
SciQ | SciQ-91 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
Sexual reproduction involves haploid gametes and produces a diploid zygote through what process? | [
"infection",
"vivisection",
"sedimentation",
"fertilization"
] | D | Sexual reproduction involves haploid gametes and produces a diploid zygote through fertilization. |
SciQ | SciQ-92 | organic-chemistry, notation
Title: Chemical formula of ethanol and other carbon compounds Should chemical formula of ethanol be written as $\ce{CH3CH2OH}$ or $\ce{C2H5OH}$? And whats the logic behind it? I have seen the former being used more often, so why is ethane represented by $\ce{C2H6}$ than $\ce{CH3CH3}$? $\ce{CH3CH2OH}$, and $\ce{C2H5OH}$ or $\ce{EtOH}$ (Ethyl OH) tells you specifically what are the bonds in the molecule. $\ce{CH3H6O}$, which would be the equivalent of writing ethane like $\ce{C2H6}$, on the other hand, tells you nothing, since it can be both ethanol or dimethyl ether. Bigger formulas can represent thousends of different compounds if written like that.
The reason why $\ce{C2H6}$ is used instead of $\ce{CH3CH3}$ is because it can only represent ethane - it's a very simple compound with no isomers, so you can write it both ways.
You can write ethanol both ways you suggested, although I've never seen $\ce{C2H5}$ instead of $\ce{Et}$ anywhere but in examples. What you shouldn't do is write it like $\ce{C2H6O}$.
If you were asking what is the logic of $\ce{CH3CH2OH}$:
What it's telling you is that the compound it is representing [ethanol] consists of a carbon atom bonded to 3 hydrogen atoms and to another carbon atom, which is bonded to 2 hydrogen atoms and 1 oxygen atom, which is finally bonded to 1 hydrogen atom, as follows:
The following is multiple choice question (with options) to answer.
All alkanes are composed of carbon and hydrogen atoms, and have similar bonds, structures, and formulas; noncyclic alkanes all have a formula of cnh2n+2. the number of carbon atoms present in an alkane has what? | [
"crippling limit",
"no limit",
"done limit",
"such limit"
] | B | All alkanes are composed of carbon and hydrogen atoms, and have similar bonds, structures, and formulas; noncyclic alkanes all have a formula of CnH2n+2. The number of carbon atoms present in an alkane has no limit. Greater numbers of atoms in the molecules will lead to stronger intermolecular attractions (dispersion forces) and correspondingly different physical properties of the molecules. Properties such as melting point and boiling point (Table 20.1) usually change smoothly and predictably as the number of carbon and hydrogen atoms in the molecules change. Properties of Some Alkanes[3] Alkane. |
SciQ | SciQ-93 | human-biology, surgery
Title: Is there a simple incision that would render a man impotent? I’m writing a novel in which two women (one of whom is a doctor) take revenge on a rapist by performing surgery on him.
What would be the simplest but most effective way of causing permanent and total erectile dysfunction?
I assume cutting one or more nerves but there are several up for contention:
The Dorsal nerve
Pudendal nerve
Inferior rectal nerve
Perineal nerve
Posterior scrotal nerves
Ideally, I’d like the surgery to be so minimally invasive that he wouldn’t even be aware that it had been done to him. You want to somehow damage the cavernous nerves of the penis. If you damage the preganglionic root of the cavernous nerves (the pelvic splanchnic nerve), you'll create all kinds of other problems.
You might also consider using a chemical agent instead of surgery; this will allow for increased discretion and ease of administration. I discuss this after the break in my answer.
Erection is driven by the parasympathetic nervous system; ejaculation is driven by the sympathetic nervous system. Since you're looking for "permanent and total erectile dysfunction," you want to disrupt parasympathetic innervation to the penis. The candidates you've mentioned (dorsal nerve, pudendal nerve, inferior rectal nerve, perineal nerve, posterior scrotal nerves) won't work since none of them provide parasympathetic innervation to the penis. Rather, the dorsal nerve of the penis is a branch of the pudendal nerve and provides sympathetic (ejaculation) and sensory innervation; the inferior rectal nerves are also branches of the pudendal nerve and provide purely somatic innervation to the anus (these lie below the pectinate line, which marks the boundary we use to define internal and external hemorrhoids); the posterior scrotal nerves are a sensory branch of the perineal nerve, which itself is a branch of the pudendal nerve. This plate from Gray's will help you visualize these relationships.
The following is multiple choice question (with options) to answer.
What percentage of men suffer from some form of erectile dysfunction by age 40? | [
"approximately 10 percent",
"approximately 60 percent",
"approximately 80 percent",
"approximately 40 percent"
] | D | Male Reproductive System Erectile dysfunction (ED) is a condition in which a man has difficulty either initiating or maintaining an erection. The combined prevalence of minimal, moderate, and complete ED is approximately 40 percent in men at age 40, and reaches nearly 70 percent by 70 years of age. In addition to aging, ED is associated with diabetes, vascular disease, psychiatric disorders, prostate disorders, the use of some drugs such as certain antidepressants, and problems with the testes resulting in low testosterone concentrations. These physical and emotional conditions can lead to interruptions in the vasodilation pathway and result in an inability to achieve an erection. Recall that the release of NO induces relaxation of the smooth muscles that surround the penile arteries, leading to the vasodilation necessary to achieve an erection. To reverse the process of vasodilation, an enzyme called phosphodiesterase (PDE) degrades a key component of the NO signaling pathway called cGMP. There are several different forms of this enzyme, and PDE type 5 is the type of PDE found in the tissues of the penis. Scientists discovered that inhibiting PDE5 increases blood flow, and allows vasodilation of the penis to occur. PDEs and the vasodilation signaling pathway are found in the vasculature in other parts of the body. In the 1990s, clinical trials of a PDE5 inhibitor called sildenafil were initiated to treat hypertension and angina pectoris (chest pain caused by poor blood flow through the heart). The trial showed that the drug was not effective at treating heart conditions, but many men experienced erection and priapism (erection lasting longer than 4 hours). Because of this, a clinical trial was started to investigate the ability of sildenafil to promote erections in men suffering from ED. In 1998, the FDA approved the drug, marketed as Viagra®. Since approval of the drug, sildenafil and similar PDE inhibitors now generate over a billion dollars a year in sales, and are reported to be effective in treating approximately 70 to 85 percent of cases of ED. Importantly, men with health problems—especially those with cardiac disease taking nitrates—should avoid Viagra or talk to their physician to find out if they are a candidate for the use of this drug, as deaths have been reported for at-risk users. |
SciQ | SciQ-94 | joining, frame
Title: Locking joints and frame construction I'm designing a large light art project and I've been trying to find kits that could essentially make lattice-like structures. For example how stages and cranes have lattice structures. The idea would be similar to wire frame floats for parades, but with adjustable locking joints and plastic or aluminum pipes.
The idea would be similar to a locking Hirth joint, but would also be universal, so I could assemble the pipes in any direction and lock them. Doesn't have to be Hirth though.
The final structure would be similar to this, but again fully adjustable and able to make different types of latticed structures.
Does anything like this exist?
Thanks Look at the scaffolding clamps - both fixed and pin- jointed.
The following is multiple choice question (with options) to answer.
What secures together immovable joints and prevents them from moving? | [
"dense collagen",
"dense cartilage",
"light cartilage",
"light collagen"
] | A | Immovable joints allow no movement because the bones at these joints are held securely together by dense collagen . The bones of the skull are connected by immovable joints. |
SciQ | SciQ-95 | seismology, earthquakes, plate-tectonics
Title: Fault representation In most illustrations and diagrams of the types of faults, there is always something similar. I noticed that there is a side of the hanging wall and foot wall which is slanted.
We're supposed to make a models for each type of fault; however, the material to be used will be difficult to cut diagonally. I'd like to know if it is necessary to have one side slanted? Or if having it vertical fine.
Please mention sources too. Thank you. Faults are results of stress. The direction of the stress controls what kind of fault that is formed. The most fundamental reason for a fault to occur is horizontal compression or extension, even if it's often more complicated in reality.
Your two examples are dip-slip faults, with a vertical displacement as a result of horizontal stress.
In your first example, the normal fault. The total distance (from left to right) is increased. There has been an extension of the crust. If the fault plane would have been vertical, no distance would have been gained.
In the second example, the reverse fault, the distance is decreased. It's been a horizontal compression of the crust. The dip of a reverse fault is usually rather steep. If the dip is lower, you'll rather form a ramp. Typical for thrust faults.
Vertical fault planes are associated with strike-slip faults or ring faults above collapsing calderas or sinkholes. It's also common, but not for textbook examples of dip-slip faults.
So, unless you are showing a strike-slip fault, you have to find a way to cut diagonally. Do measure the horizontal displacement!
Addition about making fault models:
We made a layer cake for a college some time ago and (of course) wanted to have a fault in it. The simplest way was to make a reverse fault, erode the uppermost layer of the hanging wall block and assume that the lowest exposed layer was of the same lithology (chocolate sandstone reservoir rock). However, it took some geoenginering to make it look good and we decided to make an impact crater next time.
The following is multiple choice question (with options) to answer.
Transform faults are the site of massive what? | [
"storms",
"vibrations",
"earthquakes",
"tornadoes"
] | C | Transform faults are the site of massive earthquakes. |
SciQ | SciQ-96 | thermodynamics, temperature
Title: Non uniform freezing of lakes Here's a problem from my physics textbook:
Why do lakes freeze first at the surface?
I'm not sure why this should happen, and my guess is that the only reason for this could be the temperature distribution with depth, inside water bodies. You need to know that water at $4^{\circ}$C achieve its highest density. So naturally, water at $4^{\circ}$C will tend to move to the bottom of the lake as it is heavier. When the temperature is cool enough to freeze the lake, eventually there will be some layer of ice forming at the surface but there is still liquid water below the ice layer. The ice also works as an insulation to keep the water below it from freezing to ice completely. Also, ice has a lower density than water so any ice forming will float to the surface. There are other factor like Earth's internal heating that constantly maintaining the water at the bottom of lake from freezing.
The following is multiple choice question (with options) to answer.
When water goes above and below its freezing point, what rock-breaking phenomenon is common? | [
"ice inverting",
"ice crushing",
"ice locking",
"ice wedging"
] | D | Rocks can break apart into smaller pieces in many ways. Ice wedging is common where water goes above and below its freezing point ( Figure below ). This can happen in winter in the mid-latitudes or in colder climates in summer. Ice wedging is common in mountainous regions like the Sierra Nevada pictured above. |
SciQ | SciQ-97 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
The diatoms are unicellular photosynthetic protists that encase themselves in intricately patterned, glassy cell walls composed of silicon dioxide in a matrix of organic particles. these protists are a component of freshwater and these? | [
"source plankton",
"waste plankton",
"land plankton",
"marine plankton"
] | D | The diatoms are unicellular photosynthetic protists that encase themselves in intricately patterned, glassy cell walls composed of silicon dioxide in a matrix of organic particles (Figure 23.18). These protists are a component of freshwater and marine plankton. Most species of diatoms reproduce asexually, although some instances of sexual reproduction and sporulation also exist. Some diatoms exhibit a slit in their silica shell, called a raphe. By expelling a stream of mucopolysaccharides from the raphe, the diatom can attach to surfaces or propel itself in one direction. |
SciQ | SciQ-98 | organic-chemistry, inorganic-chemistry, organic-reduction, organic-oxidation
Title: Organic chemistry Could someone tell me what happens when a compound having a benzene ring reacts with a mixture of NaOH/HCHO?
What reaction and mechanism does this follow? One example of a reaction like this is the reaction of Benzaldehyde and Formaldehyde in the presence of a basic hydroxide (OH-).
This reaction proceeds as follows:
Thus, using Sodium Hydroxide (NaOH), The reaction would yield Phenylmethanol (C6H5CH2OH) and Sodium Formate (HCOONa, sodium salt of formic acid)
If you want a better answer, or if this was not quite what you were looking for, you can try to better define your "Benzene Compound"
The following is multiple choice question (with options) to answer.
What type of reactions form compounds? | [
"chemical reactions",
"physical reactions",
"mineral reactions",
"consumption reactions"
] | A | A compound is a unique substance that forms when two or more elements combine chemically. Compounds form as a result of chemical reactions. The elements in compounds are held together by chemical bonds. A chemical bond is a force of attraction between atoms or ions that share or transfer valence electrons. For a video introduction to compounds, go to this URL: http://www. youtube. com/watch?v=-HjMoTthEZ0 . |
SciQ | SciQ-99 | 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.
Millions of years ago, plants used energy from the sun to form what? | [
"greenhouse gases",
"carbon compounds",
"fossil fuels",
"evolution"
] | B | Fossil fuels include coal, oil, and natural gas. Fossil fuels are the greatest energy source for modern society. Millions of years ago, plants used energy from the Sun to form carbon compounds. These compounds were later transformed into coal, oil, or natural gas. Fossil fuels take millions of years to form. For this reason, they are non-renewable. We will use most fossil fuels up in a matter of decades. Burning fossil fuels releases large amounts of pollution. The most important of these may be the greenhouse gas, carbon dioxide. |
SciQ | SciQ-100 | evolution, terminology, natural-selection, computational-model, definitions
On the other hand suppose we have some environment in which there are two anisofit fitness related hereditary material populations. Now if some environmental, or recombinative genetic change inflicts those two populations, that works either in a neutral manner, i.e. causes equal population sizes of those anisofit fitness related hereditary material, or works in an opposite-directional manner, i.e. in a direction that is opposite of the expected direction mentioned above, better be termed as "contra-directional". In this situation even if the size of the populations of those hereditary materials is different (imparting the appearance of a selection) still that difference is not explained by the effect of those anisofit fitness related hereditary material on their fitness in that environment! So this would not be an example of natural selection! It would be an example of an environmental factor that caused a "genetic drift", or of a genetic recombination process that caused a "genetic drift" also.
So we in effect have a struggle between "natural selection" which works in the direction of increasing adaptation with the environment, on one hand, and "random selection" (or sometimes called neutral selection or non-selection) which doesn't necessarily work in the direction of increasing adaptation with the environment.
So in some sense "evolution" is determined by the struggle of those two kinds of mechanism of change.
If random change prevails, then evolution would not necessarily move in the direction of increasing adaptation of living organisms with their environment. While if "natural selection" prevails, then evolution would proceed in the direction of increasing adaptation to the environment. I've mostly skimmed the formalism you introduced, but getting to the 2nd half of your post, the answer is yes, you understood correctly the distinction between natural selection (aka adaptive evolution) and drift (aka neutral evolution), as well as the fact that it's not a given that natural selection would be the predominant effect in arbitrary circumstances. Small population sizes, high rates of mutation, weak genetic repair mechanisms, etc. can all lead to chance being the predominant effect.
The conditions needed for natural selection to be predominant have been investigated in lots and lots of publications. A quick overview and brief list of such publications is found in
Duret, L. (2008) Neutral theory: The null hypothesis of molecular evolution. Nature Education
The following is multiple choice question (with options) to answer.
What is the term for the process in which living things with beneficial traits produce more offspring than others do? | [
"natural survival",
"natural process",
"natural variety",
"natural selection"
] | D | The other idea is that evolution occurs by natural selection. Natural selection is the process in which living things with beneficial traits produce more offspring than others do. This results in changes in the traits of living things over time. |
SciQ | SciQ-101 | thermodynamics, energy, energy-conservation, phase-transition, physical-chemistry
Title: Why is Energy change occurring during the reaction at constant temperature and constant volume given by internal energy change? When volume and temperature are kept constant, shouldn't internal energy remain constant (as it's a state function depending on state variables)? When heat is supplied, why does the internal energy increase if state variables are kept constant? For a system likely to be the seat of a chemical reaction, the variables of state are not limited to the temperature and the volume: it is necessary to add the extent of reaction.
The following is multiple choice question (with options) to answer.
In a chemical reaction, the amounts of reactants and products will be constant when what state is attained? | [
"saturation",
"homogeneity",
"peak",
"equilibrium"
] | D | The amount of reactants and products do not have to be equal. However, after equilibrium is attained, the amounts of reactants and products will be constant. |
SciQ | SciQ-102 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
What protects a developing flower while it is still a bud? | [
"shell",
"lobes",
"sepals",
"petals"
] | C | Sepals protect the developing flower while it is still a bud. Sepals are usually green, which camouflages the bud from possible consumers. |
SciQ | SciQ-103 | newtonian-mechanics, newtonian-gravity, celestial-mechanics
Title: Attraction between two objects in the universe. The resulting number of forces between them Right now I am studying Newton's Law of Universal Gravitation and I already learned his Third Law. It is said that there is an action-reaction pair between the falling apple and the Earth which results in the apple being attracted to the Earth and Earth to the apple at the same time and with the same force. But if we imagine bigger objects like Earth and Mars in the close distance, will it mean that Earth attracts to Mars and Mars is being attracted to the Earth with the gravitational force of Earth and at the same time Mars attracts to Earth and Earth to Mars because of Mars gravitational force. So as a result I counted 4 forces between two objects. Is it correct or not, and please explain why :) There's only the one gravitational interaction. You can describe it however many ways you like, but the physical interaction is only happening once.
If you want to know how two objects will move because of a force between them, relative to a distant inertial observer, calculate the change of their relative velocity by picking whatever frame measures the acceleration due to gravity that you want to integrate over time, then conserve momentum in the distant inertial frame.
For example: Bob and Alice are standing together on some frictionless ice. Bob (mass $m_B$) pushes on Alice (mass $m_A$) such that Alice has a velocity of $v$ relative to Bob. Conserve momentum $P_0$ in the frame in which you want to measure Alice's and Bob's velocity. (If this is the frame in which Alice and Bob were initially standing still, $P_0 = 0$.)
$P_0 = m_A v_a + m_Bv_b$
$v = v_a - v_b$
Solve for $v_a$ and $v_b$ in terms of $v, m_A, m_B, P_0$.
The following is multiple choice question (with options) to answer.
What is the term for the force of attraction between things that have a mass? | [
"motion",
"gravity",
"weight",
"magnetism"
] | B | Gravity has traditionally been defined as a force of attraction between things that have mass. According to this conception of gravity, anything that has mass, no matter how small, exerts gravity on other matter. Gravity can act between objects that are not even touching. In fact, gravity can act over very long distances. However, the farther two objects are from each other, the weaker is the force of gravity between them. Less massive objects also have less gravity than more massive objects. |
SciQ | SciQ-104 | bacteriology
Saier, MH. & Bogdanov, V. (2013) Membranous Organelles in Bacteria. JOURNAL OF MOLECULAR MICROBIOLOGY AND BIOTECHNOLOGY 23: 5-12 DOI: 10.1159/000346496
Free full text here.
The language used in this review seems to support the existence of mesosomes as some sort of intermediate in the formation of intracellular membranes in prokaryotes. This review is a polemic in favour of the idea that prokaryotes do indeed contain intracellular membrane-bounded compartments. It has no abstract, but the first paragraph gives a flavour of its stance:
The traditional view of life on Earth divides the living world into two major groups, prokaryotes and eukaryotes. These two groups were originally suggested to differ in very basic respects. While eukaryotes had complex cell structures including a cytoskeleton and intracellular membrane-bounded organelles, prokaryotes were believed to lack them. In fact, numerous textbooks and current sources still note this distinction and hold it to be true. For example, in Campbell’s Biology [Campbell, 1993, p. 515] it is stated without equivocation: ‘Prokaryotic cells lack membrane-enclosed organelles.’ In ‘Functional Anatomy of Prokaryotic and Eukaryotic Cells’ [Tortora et al., 2009, chapt. 4] it is similarly claimed that ‘Prokaryotes lack membrane-enclosed organelles, specialized structures that carry on various activities’. In the current Wikipedia, under ‘Prokaryote’ the following statement can be found: ‘The prokaryotes are a group of organisms whose cells lack a cell nucleus (karyon) or any other membrane-bounded organelles’. In the same online compendium under ‘Organelle’, one can read: ‘whilst prokaryotes do not possess organelles per se, some do contain protein-based microcompartments’. Proteinceous microcompartments will be the subject of a forthcoming Journal of Molecular Microbiology and Biotechnology written symposium, but this one will show that these generalizations, suggesting a lack of subcellular compartmentalization in prokaryotes, are blatantly in error [Murat et al., 2010a].
The following is multiple choice question (with options) to answer.
What are the long, thin protein extensions in most prokaryotic cells called? | [
"flagellum",
"neutrons",
"cingulum",
"analyte"
] | A | |
SciQ | SciQ-105 | organs, lifespan
Title: Organs lifespan out of the body What organ can be conserved outside of the body for the longest time and still function when reimplanted? Depends what you consider an organ. Typically though it's the cells which require the most metabolic activity which have the shortest life span. The kidney is the most of the major internal organs with up to 36 hours with liver coming second at up to 16 hours.
The following is multiple choice question (with options) to answer.
Dialysis is a treatment for failure of what organs? | [
"kidneys",
"spleen",
"liver",
"lungs"
] | A | Kidney failure may be treated with dialysis. |
SciQ | SciQ-106 | microbiology, virology, virus
Title: How does the MMR vaccine affect lymph nodes in preventing measles? I am trying to understand this statement about the Measles part of the MMR (Mumps, Measles and Rubella) vaccine
Measles prevention: MMR (AB protect during primary and secondary viremia)
Measles enters from respiratory tract, through mucosa of the upper respiratory tract. The virus passes into cervical lymph nodes. Now, starts first viremia (MMR somehow helping here) which lasts about 5 days. Then antibodies are secreted during 15 days which leads to rash lasting about 3 days.
I think this second viremia refers to the possible dissemination of the virus to other lymph nodes by blood.
This suggests me that the vaccine primarily have a mechanism that affects in the lymph nodes or generally in the lymphatic circulation.
How MMR vaccine affect lymph nodes in preventing measles? Lets define viremia first: The primary viremia occurs in the cells which the virus enters first in the body. There it replicates to high titers before it leaves this cells, spreads through the body and infects other cells. This is then the second viremia.
For measles the primary viremia occurs in the respiratory epithelium and in the local lymph nodes. The second viremia then occurs in skin, conjunctiva, respiratory tract, and other distant organs. In this phase also the characteristic rash occurs due to a hypersensitivity reaction of the skin. For details see here and here.
The measles vaccine works like any other vaccine: By raising an immune response against the vaccination virus. This leads to a normal immune response which leads to the production of specific antibodies against the measles virus and also to immunologic memory. These antibodies are available to fight the virus when it enters the body of a vaccinated person. This also triggers the proliferation of virus specific memory B cells which then differentiate into plasma cells and produce vast amounts of protective antibodies. So there is no special mechanism involved here beyond immunologic memory.
The following is multiple choice question (with options) to answer.
What preventive measure can protect even young children against diseases such as viral meningitis? | [
"nutrition",
"malnutrition",
"surgical intervention",
"vaccination"
] | D | Children as young as 2 years of age can be vaccinated against viral meningitis. |
SciQ | SciQ-107 | ## 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.
Renal plasma flow equals the blood flow per minute times the what? | [
"hematocrit",
"leukocytes",
"erythrocytes",
"hemoglobin"
] | A | Renal plasma flow equals the blood flow per minute times the hematocrit. If a person has a hematocrit of 45, then the renal plasma flow is 55 percent. 1050*0.55 = 578 mL plasma/min. |
SciQ | SciQ-108 | bond, energy, crystal-structure, ionic-compounds
$$F=\frac 1{4\pi\varepsilon_0r_0^2}Q_1Q_2$$
and thus there is less energy involved in breaking the lattice, so lattice energy decreases.
As you move down, the size increases and the valence electron in the outermost shell experiences lesser repulsion and thus it can be easily removed, therefore the elements at the bottom are highly electro-positive or conversely very less electro-negative. So when forming bonds, the elements at the bottom easily remove the electron(s) and gain more developed charged rather than the ones on the top who just release it just partially. This charge variation varies the dipole moment $\vec \mu=q\times\vec d$, by altering the partial charge $q$. Thus downwards as $q$ increases, $|\mu|$ also does increase and make the compounds formed by the element more ionic. Also the ionic/covalent character may be varied depending upon the bonding partner, in sense of, elements or other entities.
Also as charges $z^+$, $z^-$ increases, the magnitude of lattice energy does also increase as can be seen clearly from the Born-Lande equation.
$$\begin{array}{r|c|l}
&&\text{Ionic Solid}&\text{Lattice Energy (kJ/mol)}\\\hline
&\text{Variation of}&\ce{NaF}&926\\
&r_0 \text{ i.e. distance}&\ce{NaCl}&786\\
&\text{between ions}&\ce{NaBr}&752\\
&&\ce{NaI}&702\\\hline
&\text{Variation of}&\ce{NaF}&926\\
&z^+,z^- \text{ i.e. charge}&\ce{MgO}&3800\\
&\text{on ions}&\ce{Al2O3}&15900\\
\end{array}$$
The following is multiple choice question (with options) to answer.
What does lattice energy of an ionic solid measure the strength of? | [
"electrons",
"metals",
"atoms",
"bonds"
] | D | Lattice energy of an ionic solid is a measure of the strength of bonds in that ionic compound. |
SciQ | SciQ-109 | If the papillae (bumps on your tongue) can sense 5 basic tastes
and any combination of those tastes produce a unique taste,
how many possible unique tastes can you have?
. . $\displaystyle \begin{array}{ccccc} \text{1-at-a-time:} & _5C_1 &=& 5 \\ \text{2-at-a-time:} & _5C_2 &=& 10 \\ \text{3-at-a-time:} & _5C_3 &=& 10 \\ \text{4-at-a-time:} & _5C_4 &=& 5 \\ \text{5-at-a-time:} & _5C_5 &=& 1 \\ \hline & \text{Total:} && {\color{blue}31} \end{array}$
Call the five basic tastes: $\displaystyle a,b,c,d,e$
You can list them and count them yourself . . .
. . $\displaystyle \begin{array}{ccc}\text{1-at-a-time:} & a,b,c,d,e \\ \\ \text{2-at-a-time:} & ab,ac,ad,ae,bc\\ & bd,be,cd, ce, de \\ \\ \text{3-at-a-time:} & abc, abd, abe, acd, ace \\ & ade, bcd, bce, bde, cde \\ \\ \text{4-at-a-time:} & abcd, abce, abde, acde, bcde \\ \\ \text{5-at-a-time:} & abcde \end{array}$
6. Originally Posted by Soroban
Hello, Masterthief1324!
I agree with skeeter and Dinkydoe . . .
The following is multiple choice question (with options) to answer.
How many different types of taste can be detected by taste buds? | [
"two",
"five",
"three",
"hundreds"
] | B | |
SciQ | SciQ-110 | human-biology, evolution, speciation, species, human-evolution
Is this definition incorrect?
Are the publications using "species" colloquially, as opposed to scientifically?
Is "species" still a poorly defined concept? (see Ring Species)
Thanks! Short answer
The concept of species is poorly defined and is often misleading. The concepts of lineage and clade / monophyletic group are much more helpful. IMO, the only usefulness of this poorly defined concept that is the "species" is to have a common vocabulary for naming lineages.
Note that Homo neanderthalis is sometimes (although it is rare) called H. sapiens neanderthalis though highlighting that some would consider neanderthals and modern humans as being part of the same species.
Long answer
Are neanderthals and modern humans really considered different species?
Often, yes they are considered as different species, neanderthals being called Homo neanderthalis and modern humans are being called Homo sapiens. However, some authors prefer to call neanderthals Homo sapiens neanderthalis and modern humans Homo sapiens sapiens, putting both lineages in the same species (but different subspecies).
How common were interbreeding between H. sapiens and H. neanderthalis
Please, have a look at @iayork's answer.
The rest of the post is here to highlight that whether you consider H. sapiens and H. neanderthalis to be the same species or not is mainly a matter of personal preference given that the concept of species is mainly arbitrary.
Short history of the concept of species
To my knowledge, the concept of species has first been used in the antiquity. At this time, most people viewed species as fixed entities, unable to change through time and without within-population variance (see Aristotle and Plato's thoughts). For some reason, we stuck to this concept even though it sometimes appears to not be very useful.
Charles Darwin already understood that as he says in On the Origin of Species (see here)
The following is multiple choice question (with options) to answer.
What species do humans belong to? | [
"hominids",
"homo erectus",
"homo sapiens",
"monkeys"
] | C | Homo sapiens is our species. We originated about 200,000 years ago in Africa. Evidence of a spiritual life appears about 32,000 years ago. The evidence includes stone figurines that probably have religious significance ( Figure below ). |
SciQ | SciQ-111 | acid-base, titration
Title: Acid-base titration: Calculate pKa with only three values given
There's an unkown acid, diluted with an unknown amount of water and titrated with $\ce{NaOH}$.
After adding $\pu{10.00 mL}$ $\ce{NaOH}$, a $\mathrm{pH}$ value of $4.65$ is measured.
After adding another $\pu{12.22 mL}$ ($\pu{22.22 mL}$ $\ce{NaOH}$ in total), the equivalence point is reached.
Calculate the $\mathrm{p}K_\mathrm{a}$ of the acid!
The following is multiple choice question (with options) to answer.
Titration is a method to determine what in acids or bases? | [
"alkalinity",
"concentration",
"maturation",
"glucose"
] | B | The concentration of an acid or base can be determined by titration. |
SciQ | SciQ-112 | proteins, amino-acids, classification
Title: Classifying Polypeptides (and/or Proteins) Since polypeptides are a linear chain of twenty amino acids, each having a single letter abbreviation (e.g. Alanine = A). So can a polypeptide be represented as just the sequence (say: ADN for an Alanine, Aspartic acid, Asparagine polypeptide)?
This method of classifying polypeptides would lead to a possible 8000 (20**3) variations just for 3-amino-acid-polypetides (3200000 for 5-amino-acid-polypeptides, etc.) and that there would be many variations; and for longer polypeptides - that is, proteins - there would be even more variations.
Or are only the important polypeptides and proteins named, since not every variation of polypeptides and proteins are found in the body? I would've thought that many proteins (and enzymes, etc.) are incredibly specific and so they could be classified in some methodological way, as opposed to just 'lipase' or 'carbohydrase' which provides no structural information (though it would have a long methodological name). You can certainly refer to short peptides by their sequence. I don't know of any exact boundaries, but I've seen tripeptides referred to by either their three letter codes (Ala-Asp-Asn) or even the chemical name (alanylaspartylasparagine) although obviously that gets ridiculous pretty quickly.
As the largest known protein, titin also has the longest IUPAC name of
a protein. The full chemical name of the human canonical form of
titin, which starts methionyl... and ends ...isoleucine, contains
189,819 letters and is sometimes stated to be the longest word in the
English language, or any language. However, lexicographers regard generic names of chemical compounds as verbal formulae rather than English words
The following is multiple choice question (with options) to answer.
How many different amino acids make up proteins. | [
"25",
"20",
"14",
"30"
] | B | There are 20 amino acids that make up proteins. With three bases per codon, there are 64 possible codons. This is more than enough to code for the 20 amino acids plus start and stop signals. You can see how to translate the genetic code in Figure below . Start at the center of the chart for the first base of each three-base codon. Then work your way out from the center for the second and third bases. |
SciQ | SciQ-113 | organic-chemistry, acid-base, biochemistry, enzymes, medicinal-chemistry
Title: Betaine HCl stomach pH It seems betaine HCl is often recommended for those suffering from "low stomach acid" -- which, as I understand, is having too high stomach pH for proper digestion (especially for proteolysis via pepsin). However, I have a few questions then -- though I'm not sure if my reasoning is correct here:
Understandably, one wouldn't want to drink pure or highly concentrated HCl by itself to increase stomach acid! But then, what role does the betaine play?
I'm guessing betaine HCl probably does not dissolve in water to give the same pH as just straight (or concentrated) hydrochloric acid -- since then it would seem just as dangerous as drinking plain HCl!
In that case, if it doesn't decrease the pH as much, making it safe for oral consumption, what value does it bring for "lowering stomach pH" anyway? I mean, one could just drink a little vinegar or citric acid for the same effect?
Or, perhaps, is betaine-HCl just a means of some "delayed release" of HCl to lower stomach pH without hurting the mouth and esophagus during its initial consumption? Betaine may just be a useful amphoteric here, given it's quarternary ammonium and carboxylic acid groups (although not just any amphoteric, such as water, may suffice here!)
Alternatively, could the value of betaine HCl simply be in providing a source of $\ce{Cl-}$ anions, possibly for increased pepsin activity? (I'm not sure if pepsin requires merely low pH or specifically also needs $\ce{Cl-}$ anions as well) Betaine-HCl seems to be often formulated with additional pepsin enzyme(s) as well... Looks like I was right to be skeptical, according to WebMD:
The following is multiple choice question (with options) to answer.
What are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections or acidity? | [
"ulcers",
"lesions",
"hernia",
"clots"
] | A | Ulcers are sores in the lining of the stomach or duodenum that are usually caused by bacterial infections. They may also be caused by the acidic environment of the stomach. Stomach acids may damage the lining of the stomach. Symptoms typically include abdominal pain and bleeding. You can see how stomach ulcers develop at this link: http://www. youtube. com/watch?v=4bXZRgJ-1fk . |
SciQ | SciQ-114 | reproduction, sociality, fitness
Title: Which monkey species features two distinct male phenotypes? I remember coming across a popular science article years ago about a monkey species which featured two male genotypes: the first were good looking males who acquired social status (as alphas or betas) within the group and could thus achieve reproductive succes. The alternative (less frequent) phenotype achieved similar fitness by adopting an outgroup (omega) lurking rapist kind of reproductive strategy.
Does anybody know which species and whose observervations I could be referring to? I'm curious to find out if this was a valid observation and if any further research has been done on this phenomenon. Patas monkeys exhibit "sneak mating" where a male other than the resident male sires offspring. Resident males do sire more offspring than sneaker males, but both strategies do co-occur. I'm pretty sure there are other species that have a similar mating strategy as well.
The following is multiple choice question (with options) to answer.
In some species, what has led to the evolution of alternative male mating behavior and morphology? | [
"similar selection",
"sexual selection",
"distributive selection",
"sexual process"
] | B | |
SciQ | SciQ-115 | dna, chromosome
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
But Why does DNA need to be coiled tightly into chromosomes?
DNA double helix is like a telephone wire. If length is to be measured, it will go beyond 60 miles. Some even say it can make a trip to the moon more than 150,000 times. Such a long DNA molecule is not only the part of each organism's cell nucleus but also it's invisible to the naked eye. This happens just because of the high packaging and coiling of this long DNA molecule.
Let's see the diagram to get an idea.
At the bottom of the diagram there is a sequence of nucleotides (ATGC) in different combinations. This can be considered as a gene if it codes for certain protein which is required for the growth or any other function of the body.
Returning back to your question, Complimentary base pairs are not genes.
Genes are the segments of DNA which is a long sequence of nucleotide base pairs that code for any protein or RNA transcript that contributes to any trait/phenotype/function of an individual.
With the tight packaging of DNA double helix along with help of packaging proteins(Histones and Non-histones), the chromatid and chromosomes are made. The packaging of DNA to chromosomes is highly controlled and is a whole different topic in itself.
The following is multiple choice question (with options) to answer.
What structure is made from dna and protein molecules coiled together? | [
"bacterium",
"atoms",
"chromosome",
"enzymes"
] | C | As a cell prepares to divide, its DNA first forms one or more structures called chromosomes. A chromosome consists of DNA and protein molecules coiled into a definite shape. Chromosomes are circular in prokaryotes and rodlike in eukaryotes. You can see an example of a human chromosome in Figure below . The rest of the time, DNA looks like a tangled mass of strings. In this form, it would be very difficult to copy and divide. |
SciQ | SciQ-116 | energy, photons, semiconductor-physics, solar-cells
In down-conversion one high energy photon promotes an electron from 1 to 3, and by falling to energy level 2 and then 1, two photons can be emitted. Thus one high energy photon in and two low energy photons out.
Of course the next step would be to use a solar cell to collect the converted photons. The up and down converters themselves don't generate power.
Other approaches
There are other approaches to reaching higher efficiency. In specially engineered materials high energy photons can generate multiple electron-hole pairs which provides more current per photon than normal solar cells.
Then there are the hot-carrier approaches. If a material and maintain a thermal gradient then this provides an additional thermodynamic potential allowing higher efficiencies to be achieved.
You can even use hot-carrier materials as a spectral converters! I've worked on this approach over the last few years.
The following is multiple choice question (with options) to answer.
What renewable energy source converts energy from the sunlight into electricity? | [
"hydrostatic energy",
"geophysical energy",
"solar energy",
"geothermal energy"
] | C | Less energy is needed to get renewable energy sources. Solar energy is a good example. Sunlight is everywhere, so no one needs to go out and find it. We don’t have to drill for it or pump it to the surface. We just need to install solar panels like the ones in Figure below and let sunlight strike them. The energy from the sunlight is changed to electricity. The electricity is used to power lights and appliances in the house. So solar energy doesn't have to be transported. |
SciQ | SciQ-117 | human-anatomy
In the wrist, you can have palmar flexion, dorsiflexion (extension), ulnar flexion (abduction) and radial flexion (adduction) (Teachmeanatomy).
In the ankle, you can have plantar flexion, dorsiflexion (extension), inversion (inward rotation, adduction) and eversion (outward rotation, abduction). (ScienceDirect).
In the shoulder and hip, raising a limb to the same side as the limb is, is abduction (lateral extension) and raising it to the opposite side is adduction.
Moving the thumb toward the palm (in the same plane as palm) is flexion (adduction) and moving it away from it is extension (abduction).
You can read about flexion and extension and other movements here: Types of Body Movements (BCcampus)
The following is multiple choice question (with options) to answer.
The radial artery and which artery parallel their namesake bones, giving off smaller branches until they reach the wrist, or carpal region? | [
"ulnar",
"biceps",
"triceps",
"humerus"
] | A | Arteries Serving the Upper Limbs As the subclavian artery exits the thorax into the axillary region, it is renamed the axillary artery. Although it does branch and supply blood to the region near the head of the humerus (via the humeral circumflex arteries), the majority of the vessel continues into the upper arm, or brachium, and becomes the brachial artery (Figure 20.31). The brachial artery supplies blood to much of the brachial region and divides at the elbow into several smaller branches, including the deep brachial arteries, which provide blood to the posterior surface of the arm, and the ulnar collateral arteries, which supply blood to the region of the elbow. As the brachial artery approaches the coronoid fossa, it bifurcates into the radial and ulnar arteries, which continue into the forearm, or antebrachium. The radial artery and ulnar artery parallel their namesake bones, giving off smaller branches until they reach the wrist, or carpal region. At this level, they fuse to form the superficial and deep palmar arches that supply blood to the hand, as well as the digital arteries that supply blood to the digits. Figure 20.32 shows the distribution of systemic arteries from the heart into the upper limb. Table 20.9 summarizes the arteries serving the upper limbs. |
SciQ | SciQ-118 | species-identification, zoology, marine-biology, ichthyology, bone
Title: Identification of a strange skull My father is a fisherman in the Baltic sea, and he has found this very strange skull. I would like to know to which animal it belonged. Can someone help identify it? Looks like this is a neurocranium of a tuna or a similar species (dorsal view on this site).
I've also found a very similar picture of Atlantic blue tuna from USA, which seems to support that this is indeed a neurocranium.(source of the picture).
Thank you all for your help!
The following is multiple choice question (with options) to answer.
The bones of the skull are connected by what type of joints? | [
"pivoting",
"semi-mobile",
"immovable",
"adjustable"
] | C | Immovable joints allow no movement because the bones at these joints are held securely together by dense collagen. The bones of the skull are connected by immovable joints. |
SciQ | SciQ-119 | atmosphere, wind, geography, troposphere, stratosphere
Title: Other than the South Pole where is the windless place on Earth? For this other question "Would this chambered cylinder be possible", preferably near the equator where is a calmest place from the troposphere to the stratosphere where is the windless place one Earth most of the year? Not just the south pole, but 'Ridge A' and many other parts of the high Antarctic Plateau, at or about 4000 metres altitude, are generally recognized as being the least windy. Otherwise, there are a many parts of the high pressure belts at about +/- 30 degrees which have little wind for most of the year. These tend to be very dry deserts where occasional winds have momentum from other regions. On a local scale there are some deep valleys in tropical rain forests. Once you get below the canopy turbulence level they seldom receive winds of any significance - just the lightest breeze from impeded convection. However, records are hard to find because anemometers in such locations are not really representative of anything.
There is an instagram which claims that Fern tree bus stop, in Hobart, Tasmania, is the 'calmest place on Earth'.
But my experience of Hobart is that icy winds in winter can be far from calm.
These things are relative. Compared to the 2100 km/hour winds of Neptune, everywhere on our planet is as close to windless as makes no difference.
The following is multiple choice question (with options) to answer.
What is the lowest layer of the atmosphere? | [
"chromosphere",
"ionosphere",
"lithosphere",
"troposphere"
] | D | The troposphere is the lowest layer of the atmosphere. All of the air you breathe is in the troposphere. All of Earth's weather—wind, rain, snow, heat—is in the troposphere. The troposphere is the lowest and most important layer of the atmosphere!. |
SciQ | SciQ-120 | 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 the name of the type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate? | [
"bundle sheth cell",
"cuticle",
"meristem",
"guard cell"
] | C | The key to continued growth and repair of plant cells is meristem . Meristem is a type of plant tissue consisting of undifferentiated cells that can continue to divide and differentiate. Meristem at the tips of roots and stems allows them to grow in length. This is called primary growth. Meristem within and around vascular tissues allows growth in width. This is called secondary growth. |
SciQ | SciQ-121 | evolution
bacteria
cyanobacteria
archaea
protists
fungi
algae
plants
nematodes
arthropods
vertebrates
Bacterial and archaean colonisation
The first evidence of life on land seems to originate from 2.6 (Watanabe et al., 2000) to 3.1 (Battistuzzi et al., 2004) billion years ago. Since molecular evidence points to bacteria and archaea diverging between 3.2-3.8 billion years ago (Feng et al.,1997 - a classic paper), and since both bacteria and archaea are found on land (e.g. Taketani & Tsai, 2010), they must have colonised land independently. I would suggest there would have been many different bacterial colonisations, too. One at least is certain - cyanobacteria must have colonised independently from some other forms, since they evolved after the first bacterial colonisation (Tomitani et al., 2006), and are now found on land, e.g. in lichens.
Protistan, fungal, algal, plant and animal colonisation
Protists are a polyphyletic group of simple eukaryotes, and since fungal divergence from them (Wang et al., 1999 - another classic) predates fungal emergence from the ocean (Taylor & Osborn, 1996), they must have emerged separately. Then, since plants and fungi diverged whilst fungi were still in the ocean (Wang et al., 1999), plants must have colonised separately. Actually, it has been explicitly discovered in various ways (e.g. molecular clock methods, Heckman et al., 2001) that plants must have left the ocean separately to fungi, but probably relied upon them to be able to do it (Brundrett, 2002 - see note at bottom about this paper). Next, simple animals... Arthropods colonised the land independently (Pisani et al, 2004), and since nematodes diverged before arthropods (Wang et al., 1999), they too must have independently found land. Then, lumbering along at the end, came the tetrapods (Long & Gordon, 2004).
Note about the Brundrett paper: it has OVER 300 REFERENCES! That guy must have been hoping for some sort of prize.
References
The following is multiple choice question (with options) to answer.
Phosphate-containing ocean sediments form primarily from the bodies of ocean organisms and from their what? | [
"excretions",
"blood",
"ancestors",
"skeletons"
] | A | The Phosphorus Cycle Phosphorus is an essential nutrient for living processes; it is a major component of nucleic acids and phospholipids, and, as calcium phosphate, makes up the supportive components of our bones. Phosphorus is often the limiting nutrient (necessary for growth) in aquatic, particularly freshwater, ecosystems. Phosphorus occurs in nature as the phosphate ion (PO43-). In addition to phosphate runoff as a result of human activity, natural surface runoff occurs when it is leached from phosphate-containing rock by weathering, thus sending phosphates into rivers, lakes, and the ocean. This rock has its origins in the ocean. Phosphate-containing ocean sediments form primarily from the bodies of ocean organisms and from their excretions. However, volcanic ash, aerosols, and mineral dust may also be significant phosphate sources. This sediment then is moved to land over geologic time by the uplifting of Earth’s surface. (Figure 20.13) Phosphorus is also reciprocally exchanged between phosphate dissolved in the ocean and marine organisms. The movement of phosphate from the ocean to the land and through the soil is extremely slow, with the average phosphate ion having an oceanic residence time between 20,000 and 100,000 years. |
SciQ | SciQ-122 | newtonian-mechanics, estimation
Would the rock have created a seismic event of its own (if so, how large)?
Would the rock have created a crater? The energy of the rock at the time of hitting the earth is mgh.
No rock we know of is going to be able to survive this collision with out breaking into pieces.
Non the less it will be a big impact and depending on the geology of the location it hits a variety of reactions scenarios can happen.
If the soil is aggregate of silt and sand and gravel, it would part into several shear rupture sections which look like slices of shell pattern surfaces starting from the bottom surface of the rock and turning up exiting the earth surface a few hundred yards outside of the impact zone and probably even eject some material out like a bomb crater. This scenario will have shakes that could be recorded miles away.
The calculation of how much of the momentum of rock will be shared with the shear material and accelerating them will be involved but not impossible.
If the geology of the impact area is of very low bearing like mostly silt and loose clays, the rock my lose most of its kinetic energy by just sinking into the dirt mostly with a giant humph with a cloud of dust rising.
If the geology is hard or rocky with the 'optimal' amount of mass and resilience it could create a substantial earthquake by resonating with the impact.
The following is multiple choice question (with options) to answer.
What does erosion do to pieces of broken rock? | [
"lead them",
"Smooth them",
"Cancel Them",
"moves them"
] | D | Erosion moves the pieces of broken rock. |
SciQ | SciQ-123 | gene, genetics
Title: How long does it take for a person to lose all offsprings due to inheritance? From this I know we will only inherit some genetic informations from parents, which is about 50 percent. But the problem is, gene has finite size, after some generations a person leaves only $0.5 \times 0.5 \times 0.5$ parts of genes to the offsprings, and it will be casted into zero. My question is, how long does it required for a person to lose all genetic information in the world? I think your question conveys some misunderstanding.
A child is related to each parent by a factor of ½. Humans have a diploid genome, meaning they have two copies of each chromosome (see: autosome). When two humans reproduce, they each contribute one copy of each chromosome to the offspring, in other words, they contribute a haploid genome to make a diploid child. Genetic information is not "lost" - the genome is not shrinking by a factor of ½ every generation.
However, relatedness does decrease from generation to generation. You are related to each of your parents by a factor of ½, each of your grandparents by a factor of ½ $\times$ ½, your great-grandparents by a factor of ½ $\times$ ½ $\times$ ½... You are also related to your children by a factor of ½, you are related to your grandchildren by a factor of ½ $\times$ ½... You get the picture, right?
For example, imagine the genome carries just one gene. Your father carries alleles $AA$ at that locus, and your mother $aa$. You would then be $Aa$ and, because half of your alleles came from your father and the other half from your mother, be related to each by a factor of ½, but all three of you have the same number of genes (1) and that gene is the same length (in nucleotides, barring mutations) in all three.
The following is multiple choice question (with options) to answer.
The passing of traits from parents to offspring is done through what? | [
"sperm",
"dna",
"blood",
"egg"
] | B | Genetics is the study of inheritance. Inheritance is the passing of traits from parents to offspring. How are these traits "passed"? Through DNA, which is the genetic material of all organisms. This concept will focus on genetics, inheritance, and DNA. |
SciQ | SciQ-124 | pressure, ideal-gas, kinetic-theory, evaporation
Title: Finding the equilibrium vapor pressure of two solutions(of different concentrations) enclosed in a vessel
The saturated vapour pressure above
an aqueous solution of sugar is known to be
lower than that above pure water, where
it is equal to $p_{sat}$, by $\Delta p = 0.05p_{sat}c$.
where c is the molar concentration of the
solution. A cylindrical vessel filled to
height $h_1 =10$cm with a sugar solution of
concentration $c_1 = 2\times 10^{-3}$ is placed under
a wide bell jar. The same solution of concentration
$c_2 = 10^{-3}$ is poured under the
bell to a level $h_2$ << $h_1$ (Shown in the given figure).Determine the level h of the solution in
the cylinder after the equilibrium has been
set in. The temperature is maintained constant
and equal to 20 °C. The vapour above
the surface of the solution contains only
water molecules, and the molar mass of
water vapour is $\mu = 18\times 10^{-3}$ kg/mol.
The following is multiple choice question (with options) to answer.
In a glass of sweet tea the sugar is known as the solute and the water is known as what? | [
"pigment",
"calcium",
"solid",
"solvent"
] | D | If you’re like Tanya in this picture, you prefer your iced tea sweetened with sugar. Sweetened iced tea is a solution in which solid sugar (the solute) is dissolved in cold liquid tea, which is mostly water (the solvent). When you add sugar to tea, particles of water pull apart particles of sugar. The particles of sugar spread throughout the tea, making all of it taste sweet. |
SciQ | SciQ-125 | geophysics, earthquakes, plate-tectonics, geography
Title: Why is the Ring of Fire there? The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else?
Any help would be appreciated! This question is very similar to: Why does the "Ring of Fire" pretty much define "Pacific Rim"
The high levels of volcanoes and earthquakes are primarily due to subduction. So why is the Pacific surrounded by subduction zones?
Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it. This destruction of the ocean plate(s) occurs at subduction zones.
This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.
The following is multiple choice question (with options) to answer.
A few earthquakes take place away from plate boundaries, these are called what? | [
"deformation earthquakes",
"intraplate earthquakes",
"outer earthquakes",
"distant earthquakes"
] | B | The remaining 5% are scattered around other plate boundaries. A few earthquakes take place away from plate boundaries. These are intraplate earthquakes. |
SciQ | SciQ-126 | acid-base, reaction-mechanism
Title: Litmus paper - turning red, blue and even bleached I have blue litmus paper, and if I put it in an acid it turns red. I also have red litmus paper, and if I put it in a base, it turns blue.
I know the question about litmus was asked and answered and I like the answer:
How does the litmus pH indicator work?
However, damp litmus paper also becomes bleached in presence of chlorine gas. I believe it has nothing to do with the mechanism described in aforementioned question. I wonder what the mechanism is. Wikipedia actually suggests:
For instance, chlorine gas turns blue litmus paper white – the litmus dye is bleached, because of presence of hypochlorite ions. This reaction is irreversible, so the litmus is not acting as an indicator in this situation.
I also found an equation which describes formation of hypochloric acid (source):
$$\ce{Cl2 (g) + H2O (l) -> HClO (aq) + HCl (aq)}$$
The problem that I have now is as follows: We know that litmus paper gets discolored because of contact with hypochloric acid. But what is actually the chemical reaction for that? I can supply some details now, and hopefully this ought to qualify as an answer.
As I mentioned earlier litmus is a mixture of 10-12 dyes (CAS number: 1393-92-6).
The acid-base indicator properties of litmus are primarily due to 7-hydroxyphenoxazone chromophore (pictured below)
The answer you linked to discusses the acid-base indication mechanism in some detail, so I shall skip over that.
Anyway, what this serves to establishing that it is indeed a extended $\pi$-conjugated system that we are dealing with in the chromophore.
Now, $\ce{HOCl}$ would bring about halohydrination (basically an electrophilic addition) across the $\pi$ bonds, thus disrupting the conjugated system.
Halohydrins are compounds that contain an $\ce{-OH}$ and $\ce{-X}$ groups on adjacent carbons.
This image describes the general mechanistic scheme in a simpler case:
The following is multiple choice question (with options) to answer.
Red litmus paper turns what color when placed in a basic solution? | [
"white",
"blue",
"pink",
"orange"
] | B | Red litmus paper turns blue when placed in a basic solution. |
SciQ | SciQ-127 | electrochemistry, redox, equilibrium, ph, concentration
Therefore, if you link two Standard Hydrogen Electrodes, you won't be able to measure a voltage.
If you don't intend to have standard conditions however, the reduction will indeed take place in the more acedic half-cell (simply spoken). This is also indicated by the electrode potential you calculated: -0,059V * pH. The reduction takes place in the half-cell with the higher potential and the potential you calculated increases with lower pH (more acedic solution).
The following is multiple choice question (with options) to answer.
The difference between the theoretical half-reaction reduction potential and the actual voltage required is called what? | [
"overcharge",
"excess",
"overpotential",
"resistance"
] | C | can occur in electrolytic cells by introducing a power supply, which supplies the energy to force the electrons to flow in the nonspontaneous direction. Electrolysis is done in solutions, which contain enough ions so current can flow. If the solution contains only one material, like the electrolysis of molten sodium chloride, it is a simple matter to determine what is oxidized and what is reduced. In more complicated systems, like the electrolysis of aqueous sodium chloride, more than one species can be oxidized or reduced and the standard reduction potentials are used to determine the most likely oxidation (the half-reaction with the largest [most positive] standard reduction potential) and reduction (the half-reaction with the smallest [least positive] standard reduction potential). Sometimes unexpected half-reactions occur because of overpotential. Overpotential is the difference between the theoretical half-reaction reduction potential and the actual voltage required. When present, the applied potential must be increased, making it possible for a different reaction to occur in the electrolytic cell. The total charge, Q, that passes through an electrolytic cell can be expressed as the current (I) multiplied by time (Q = It) or as the moles of electrons (n) multiplied by Faraday’s constant (Q = nF). These relationships can be used to determine things like the amount of material used or generated during electrolysis, how long the reaction must proceed, or what value of the current is required. |
SciQ | SciQ-128 | human-biology, eggs
In order to form a zygote (fertilized egg) to develop properly into a fetus it has to be an environment to meet it needs. In a female uterus all these needs are met but replicating them might be difficult. An artificial womb would have to be able to provide nutrients, oxygen, and channels for the development process of a fetus as well as system to expel (birth) the fetus once its development is complete. So can today's technology and science do all this? In theory yes, if resources and time where dedicated (and red tape cut) it would be possible to develop a fertilized egg in an artificial environment within the foreseeable future. There have been multiple experiment where artificial wombs were implanted with fertilized eggs and began to grow but were stopped due to legality.
I encourage you to read the following Wikipedia and motherboard articles regarding artificial wombs and ectogenesis.
https://en.wikipedia.org/wiki/Artificial_uterus
http://motherboard.vice.com/read/artificial-wombs-are-coming-and-the-controversys-already-here
*Note there is a lot of biology I did not mention regarding zygote to fetus development which is the biggest question/obstacle that ectogenesis might face
The following is multiple choice question (with options) to answer.
While the egg is developing, other changes are taking place in the uterus. it develops a thick lining that is full of what? | [
"tiny blood vessels",
"amniotic fluid",
"white blood cells",
"large arteries"
] | A | While the egg is developing, other changes are taking place in the uterus. It develops a thick lining that is full of tiny blood vessels. The lining prepares the uterus to receive a fertilized egg if fertilization actually takes place. |
SciQ | SciQ-129 | neuroscience, neuroanatomy
Likewise, the spinal chord is structured into sensory and motor regions. In summary, the spinal chord consists of: 1) cell bodies (motor, sensory, inter; grey in the picture), 2) ascending axons (blue), 3) descending axons (red). Similar to nerves, axons going up or down the spinal chord are bundled into "tracts". Sensory axons are never bundled with motor axons, making it possible to create a map of the spinal chord in cross-section.
The tracts' names might be a bit confusing at first, but on second look are actually pretty self-explanatory. They usually contain where the axons come from and where they are going in order to synapse with other neurons. E.g. the spinocerebellar tract is formed of axons coming from the spine and going to the cerebellum. Given that the cerebellum is near the brain and the spine is further down, this is obviously an ascending tract - and ascending tracts are always sensory (because sensory information never needs to be carried downwards due to the brain being at the top).
Where it gets blurry
The sensory/motor separation isn't always as clear as I've described above. In fact, nerves (bundles of axons anywhere in the body outside of the CNS) will usually contain both sensory and motor pipelines. In particular, the cranial nerves (12 of the most important nerves) all include sensory and motor components for the respective part of the body that they manage. E.g. the facial nerve contains both the sensory connections for parts of the tongue and the motor connections that control facial muscles.
Another more complex example is pain sensation, where interneurons in the spinal chord can feed back onto sensory neurons and inhibit their signals, or axons can inhibit those packed in the same nerve bundle simply due to electrical effects.
The following is multiple choice question (with options) to answer.
The neural plate undergoes a series of cell movements where it rolls up and forms a tube called what? | [
"occular tube",
"neural tube",
"cell tube",
"peripheral tube"
] | B | called growth factors signal some cells at the edge of the ectoderm to become epidermis cells. The remaining cells in the center form the neural plate. If the signaling by growth factors were disrupted, then the entire ectoderm would differentiate into neural tissue. The neural plate undergoes a series of cell movements where it rolls up and forms a tube called the neural tube, as illustrated in Figure 43.28. In further development, the neural tube will give rise to the brain and the spinal cord. |
SciQ | SciQ-130 | biochemistry, molecular-biology, cell-biology, cell-membrane
Once you have a firm grasp on that, consider that in order for a hydrophobic molecule to reach a plasma membrane, it must already be solvated by water. The transfer of a hydrophobe from one hydrophillic environment (water) to another (head groups of the phospholipids in the plasma membrane) should be energetically negligible. The limiting step for passive diffusion across a membrane is transfer from the hydrophillic environment of the phospholipid head groups to the hydrophobic environment of their tails. In fact, the rate of diffusion across a plasma membrane increases with hydrophobicity.
The following is multiple choice question (with options) to answer.
Due to the __________ nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot easily diffuse across the cell membrane. | [
"catalytic",
"saturated",
"hydrophobic",
"hydrophylic"
] | C | Small nonpolar molecules can easily diffuse across the cell membrane. However, due to the hydrophobic nature of the lipids that make up cell membranes, polar molecules (such as water) and ions cannot do so. Instead, they diffuse across the membrane through transport proteins. A transport protein completely spans the membrane, and allows certain molecules or ions to diffuse across the membrane. Channel proteins, gated channel proteins, and carrier proteins are three types of transport proteins that are involved in facilitated diffusion. |
SciQ | SciQ-131 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
In what way do all vertebrates reproduce? | [
"sexually",
"biologically",
"asexually",
"mitosis"
] | A | Vertebrates reproduce sexually, and almost all have separate male and female sexes. Aquatic species generally have external fertilization, whereas terrestrial species usually have internal fertilization. Vertebrates have one of three reproductive strategies, known as ovipary, ovovivipary, or vivipary. |
SciQ | SciQ-132 | cell-biology, cell-culture
Cell Membrane Changes:
Cell membrane to become less fluid,
potentially affecting its permeability and functionality.
Ice Formation:
Extreme cold can cause ice crystals to form
within and around the cells.
But I really want to see these up close under a microscope.
The temperatures don't have to be extreme. Just like mildly cold ice water vs. a warm shower. When the cold water hits a cell do you see it like bounce off? When the warm water hits a cell do you see it enter the cell? You can't see these changes easily under a microscope. It is a challenge to add heat or cold to cells on a microscope in a manner that you might see, unless you have the right equipment.
You might see protein denaturation - it's like an egg cooking, but because the cells are so small, it happens very fast and you aren't left with a residue, the cells detach before this happens or just disintegrate. For this to happen you need to be heating above about 55 - 65 C (131 - 149 F) for observable denaturation - this is about the same temp as egg white denatures (IIRC 61 C/141 F), but some proteins denature much earlier. Part of the reason it is so difficult to see is the range of temperatures it happens over, so the process is spread out.
Membrane fluidity is not something you will see at all unless you are making specific measurements of it - the cells just don't move enough for you to notice the difference between warm and cold. Water doesn't "bounce off" or enter cells because of membrane fluidity - it enters through protein channels called aquaporins - you can't see these either, far far far too small for light microscopy.
Adding water to the cells (note - cells don't like water in general, mammalian cells need isoosmotic conditions with some salt to keep them happy or they undergo osmotic stress and pop, which you might see, but it isn't dramatic at all). As they are already in a liquid - Have you ever added hot water to cold - how much difference do you see? How would you know when the cold/hot water reached the cells?
The following is multiple choice question (with options) to answer.
First, high temperature denatures proteins and does what to cells? | [
"finds them",
"exposes them",
"develops them",
"kills them"
] | D | |
SciQ | SciQ-133 | organic-chemistry, molecular-structure
The deposit of a single molecule on a clean, flat, and cold surface. From the outsider's perception of work done @IBM Zurich and other groups, preparing such a pad accommodating an organic molecule is something understood well; perhaps some adjustments in how the molecules are then deposited are needed. Are nanoputains as substance well sublimable, would be OMBE feasible?
The cold surface tightens the contact between molecule and substrate, lowers thermal vibrations of the molecule deposited; contributes that the then collected AFM is crisp. Provided the earlier mentioned conformational flexibility of the material (not necessary flat molecule, either), how do you -- if necessary -- decoil the members of a nanoputain? To move small molecules entirely, optical tweezers come to my mind, but here it were moving just a portion of a molecule representing a leg, redressing bow tie and hat that I assume as even more delicate.
So my speculation is the second part is the more challenging one. Maybe it was already addressed as the original work was published in 2003, a citation analysis may shed some light on this aspect.
The following is multiple choice question (with options) to answer.
What term is used to describe a collection of molecules surrounded by a phospholipid bilayer that is capable of reproducing itself? | [
"organism",
"proteins",
"cell",
"atom"
] | C | A cell membrane is essentially a mixture of phospholipids that form a phospholipid bilayer. One definition of a cell is a collection of molecules surrounded by a phospholipid bilayer that is capable of reproducing itself. The simplest cells are bacteria, which consist of only a single compartment surrounded by a single membrane. Animal and plant cells are much more complex, however, and contain many different kinds of compartments, each surrounded by a membrane and able to carry out specialized tasks. |
SciQ | SciQ-134 | human-biology
Title: Stopping the effect of hormone Many hormones released by endocrine organs travel down in the blood and bind to specific receptors on the target cells. What then breaks that binding of the molecule with the receptor ? ( thus inactivating further stimulation of the target cell ) The binding is reversible typically; part of the potency of a drug is ow well and for how long it binds to its target. There's a natural equilibrium of binding and dissociation. Many drugs, once bound to their cognate receptor, cause a down regulation of their cognate receptor on the target cell. The bound/activated downstream signalling pathways may be inhibited by ubiquitination of the downstream signals themselves or upregulation of antagonists etc. The hormone itself has a half life, which is very important, thus levels naturally decrease and for some hormones this is incredibly rapid. Levels may decrease due to breakdown or excretion. Increase of binding hormones may decrease free hormone thus it's effect also.
The following is multiple choice question (with options) to answer.
By allowing blood levels of a hormone to be regulated within a narrow range, feedback loops contribute to maintaining what state? | [
"hibernation",
"homeostasis",
"hypothesis",
"consciousness"
] | B | Role of Feedback Loops The contribution of feedback loops to homeostasis will only be briefly reviewed here. Positive feedback loops are characterized by the release of additional hormone in response to an original hormone release. The release of oxytocin during childbirth is a positive feedback loop. The initial release of oxytocin begins to signal the uterine muscles to contract, which pushes the fetus toward the cervix, causing it to stretch. This, in turn, signals the pituitary gland to release more oxytocin, causing labor contractions to intensify. The release of oxytocin decreases after the birth of the child. The more common method of hormone regulation is the negative feedback loop. Negative feedback is characterized by the inhibition of further secretion of a hormone in response to adequate levels of that hormone. This allows blood levels of the hormone to be regulated within a narrow range. An example of a negative feedback loop is the release of glucocorticoid hormones from the adrenal glands, as directed by the hypothalamus and pituitary gland. As glucocorticoid concentrations in the blood rise, the hypothalamus and pituitary gland reduce their signaling to the adrenal glands to prevent additional glucocorticoid secretion (Figure 17.6). |
SciQ | SciQ-135 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Collagen fibers, elastic fibers, and reticular fibers comprise what type of tissue? | [
"intestine tissue",
"connective tissue",
"nucleus tissue",
"skin tissue"
] | B | Connective Tissue Fibers and Ground Substance Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fiber is made from fibrous protein subunits linked together to form a long and straight fiber. Collagen fibers, while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the movement of the body. Elastic fiber contains the protein elastin along with lesser amounts of other proteins and glycoproteins. The main property of elastin is that after being stretched or compressed, it will return to its original shape. Elastic fibers are prominent in elastic tissues found in skin and the elastic ligaments of the vertebral column. Reticular fiber is also formed from the same protein subunits as collagen fibers; however, these fibers remain narrow and are arrayed in a branching network. They are found throughout the body, but are most abundant in the reticular tissue of soft organs, such as liver and spleen, where they anchor and provide structural support to the parenchyma (the functional cells, blood vessels, and nerves of the organ). All of these fiber types are embedded in ground substance. Secreted by fibroblasts, ground substance is made of polysaccharides, specifically hyaluronic acid, and proteins. These combine to form a proteoglycan with a protein core and. |
SciQ | SciQ-136 | human-biology, biochemistry, molecular-biology, cell-membrane, pulmonology
Title: How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)? How does lipoid pneumonia lead to acute respiratory distress syndrome (ARDS)?
The vaping illnesses that have been happening on the news in the United States are being caused by the federal prohibition on marijuana. Smugglers will legally go to recreational marijuana dispensaries in legal states and purchase cartridges that contain about a gram of "wax". Proper cartridges will use polyethylene glycol, polypropylene glycol, or vegetable glycerin to suspend the THC for vaporizing, but the smugglers have been known to open up the tank and remove some of the wax and refill the remaining volume with Vitamin E Oil. These tampered cartridges are then sold on the black market to recreational and medical consumers in illegal states.
The CDC Report: "Outbreak of Lung Injury Associated with the Use of E-Cigarette, or Vaping, Products"
Edit: So, I was on some conspiracy shtuff when I wrote this post because I was worried about impurities in my vapes killing me. I don't want to take this down because I want my cognitive distortion to remain visible as a reminder of how we can succumb to biased reasoning. Also, the answer I marked correct contextualized the fragmented information of which I was aware and attempted to give me an improved framework for understanding the terms I was using incorrectly as a layman. There are several ways to get ARDS (sepsis, pneumonia, trauma, pancreatitis, etc). Pathophysiologically, they all converge at alveolar insult. So however it happens, there's alveolar insult, cytokine release that recruits neutrophils, and the activated neutrophils release toxic mediators that destroy the alveolar membranes. So for your question specifically, the mineral oil in the vape cartridges (theoretically) is instigating an inflammatory reaction that destroys alveolar membranes.
The following is multiple choice question (with options) to answer.
What the name of the disease where some of the alveoli of the lungs fill with fluid so they can no longer exchange gas? | [
"lung cancer",
"pneumonia",
"leukemia",
"emphysema"
] | B | Pneumonia is a disease in which some of the alveoli of the lungs fill with fluid so they can no longer exchange gas. Symptoms of pneumonia typically include coughing, chest pain, difficulty breathing, and fatigue. Pneumonia may be caused by an infection or an injury to the lungs. |
SciQ | SciQ-137 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
What occurs when groups from the same species stop mating because of something other than physical or geographic separation? | [
"complementary speciation",
"sympatric speciation",
"invasive speciation",
"extinction"
] | B | Sympatric speciation occurs when groups from the same species stop mating because of something other than physical or geographic separation. The behavior of two groups that live in the same region is an example of such separation. The separation may be caused by different mating seasons, for example. Sympatric speciation is more difficult to identify. |
SciQ | SciQ-138 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
What environment do animals with gills live in? | [
"air",
"underground",
"water",
"cold"
] | C | |
SciQ | SciQ-139 | thermodynamics, temperature, boiling-point
Title: How it was decided that the freezing point of water in the Kelvin scale of temperature should be 273.15 K? While discussing about the different temperature scales, our teacher told us about the freezing point and boiling point of water in different scales. I asked my teacher that how these numbers were decided, like why it was decided that 273.15 should be the freezing point of water in Kelvin scale and not some other number, but could not get a satisfactory answer. So, here I am requesting if anyone could tell me the reasons for giving the different specific numbers in different scales for the same temperature, in the simplest way possible. History: the Celsius scale was defined first; the zero on the Kelvin scale is dependent on that definition
It may seem awkward and annoying that the zero point on the Kelvin scale (and therefore the freezing point of water) isn't an exact number, but it is a consequence of history.
There used to be a variety of different temperature scale in the early history of chemistry. The Fahrenheit scale annoyingly used by a small number of countries to confuse science students, is one legacy of that era. And this matters because of how the scales were defined.
The original definition of the celsius scale was based on the freezing point and boiling point of pure water under very carefully defined conditions. The difference between the two temperatures was divided into 100 for convenience (it is certainly more convenient than the Fahrenheit scale which divides that interval into 180 parts though the original definition of the endpoints was more complicated and convoluted). The Kelvin scale came later but uses exactly the same interval as the celsius scale. The bp was set at 100 celsius and the freezing point at 0 celsius.
But this definition occured long before we knew there was an absolute lower limit for temperature. And it was based on empirical observations. When chemists and physicists got to grips with thermodynamics and started to explore really low temperatures, it was too late to define a new scale with different definitions. So when experiments revealed that there was a lower limit, absolute zero, they could only measure what that number was on the celsius scale as it made little sense to devise a new scale and mess with all the existing definitions.
The following is multiple choice question (with options) to answer.
What is the boiling and freezing point of water in celcius? | [
"212 degrees c and 32 degrees c",
"100 degrees c and 32 degrees c",
"100 degrees c and 0 degrees c",
"212 degrees c and 0 degrees c"
] | C | Melting and boiling points are somewhat unique identifiers, especially of compounds. In addition to giving some idea as to the identity of the compound, important information can be obtained about the purity of the material. |
SciQ | SciQ-140 | zoology, digestive-system, pets
Title: Is it safe to feed an adult fire salamander with slime maggots? As a reminder, maggots feed of a flesh, while fire salamander consumes his prey alive, without killing it.
Can it happen that the maggot will start eating the salamander from the inside? Although I am afraid I don't know much about fire salamanders specifically, it is certainly possible for ingested fly larvae (or larvae hatching from ingested eggs) to survive ingestion and subsequently cause intestinal damage. Parasitic infestation by fly larvae that grow inside the host while feeding on its tissue is called myiasis. Enteric myiasis (also called gastric, rectal, or intestinal myiasis to indicate the affected part of the digestive system) occurs occasionally in humans following the ingestion of cheese infested with cheese fly maggots. Casu marzu, a traditionally produced Sardinian cheese, is supposed to have live cheese fly maggots in it, and cases of bloody diarrhoea following its consumption are known. If they're dead the cheese is considered unsafe to eat (although personally I'd correct that to 'more unsafe').
The following is multiple choice question (with options) to answer.
What are living things that obtain glucose by eating self feeders called? | [
"producers",
"chimeras",
"heterotrophs",
"viruses"
] | C | Types of organisms that make glucose by photosynthesis are pictured in Figure below . They include plants, plant-like protists such as algae, and some kinds of bacteria. Living things that make glucose are called autotrophs ("self feeders"). All other living things obtain glucose by eating autotrophs (or organisms that eat autotrophs). These living things are called heterotrophs ("other feeders"). |
SciQ | SciQ-141 | 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.
Virtually every task performed by living organisms requires this? | [
"solids",
"mineral",
"energy",
"metals"
] | C | Introduction Virtually every task performed by living organisms requires energy. Energy is needed to perform heavy labor and exercise, but humans also use energy while thinking, and even during sleep. In fact, the living cells of every organism constantly use energy. Nutrients and other molecules are imported into the cell, metabolized (broken down) and possibly synthesized into new molecules, modified if needed, transported around the cell, and possibly distributed to the entire organism. For example, the large proteins that make up muscles are built from smaller molecules imported from dietary amino acids. Complex carbohydrates are broken down into simple sugars that the cell uses for energy. Just as energy is required to both build and demolish a building, energy is required for the synthesis and breakdown of molecules as well as the transport of molecules into and out of cells. In addition, processes such as ingesting and breaking down pathogenic bacteria and viruses, exporting wastes and toxins, and movement of the cell require energy. From where, and in what form, does this energy come? How do living cells obtain energy, and how do they use it? This chapter will discuss different forms of energy and the physical laws that govern energy transfer. This chapter will also describe how cells use energy and replenish it, and how chemical reactions in the cell are performed with great efficiency. |
SciQ | SciQ-142 | immunology, pathology, pathophysiology
SRC
You can see in healthy phagocytes that through one of two pathways, protein antigens end up displayed on HLA molecules for cellular immunity to take over. Option B is that another cell like a macrophage detects distress signals from the infected cell and induces cell death in it through receptors or oxidative burst. In the case of Salmonella, HLA expression is down-regulated and oxidative burst can be inhibited so localized, infected antigen-presenting cells cant mount an effective response.
That's not to say everything is de-regulated early on. If you succeed in antigen presentation or innate killing (perhaps a non-pathogenic strain), you will resolve the infection as seen in the above figure: a combination of T-mediated killing, B-mediated killing, NK-mediated killing, and generalized inflammation.
In the chronic case, the pathogen will have escaped the primary immune response, but the system will attempt to continue to resolve the infection. This can lead to a number of things: cellular anergy, cellular hyperactivity, sequestration (see granuloma), chronic inflammation & tissue damage, and so forth. The following diagram is predicated upon viral infections but the immunology is largely similar:
SRC
There are changes to the system that are a result of over-exposure to antigen, and an inability to clear that stimulation. The best way to explain it is that chronic stimulation leads to both hyperactivity and suppression. The constant presence of effector molecules like TNF-a leads to a persistent state of tissue inflammation, which is bad for the tissue, but taken together with the persistent presence of antigen, this may lead to dysfunctional responses by lymphocytes (3).
A particularly virulent infection may be impossible for your immune system to clear without assistance, then, requiring the intervention of gram-negative antibiotics, for example.
The following is multiple choice question (with options) to answer.
The binding of what helps eliminate antigens by phagocytosis and complement-mediated lysis | [
"antibodies",
"proteins",
"fats",
"amino acids"
] | A | |
SciQ | SciQ-143 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
What muscles are used to pump water over the gills? | [
"lungs and pharynx",
"muscles and pharynx",
"jaws and pharynx",
"pharynx and tonsils"
] | C |
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