source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3244 | 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.
Prokaryotic cells have what structure outside their plasma membrane? | [
"cell wall",
"sodium channel",
"cell membrane",
"plasma wall"
] | A | Most prokaryotic cells are much smaller than eukaryotic cells. They have a cell wall outside their plasma membrane. Prokaryotic DNA consists of a single loop. Some prokaryotes also have small, circular pieces of DNA called plasmids. |
SciQ | SciQ-3245 | cell-biology, molecular-biology
Title: Intracellular lipid transport I know that lipids are carried around the body in the blood either as micelles or by lipid-binding proteins which allow them to be solved.
Lipids can't always be integrated in a membrane though, the phospholipids used in membranes have to be synthesised somewhere from a precursor which will also by hydrophobic.
Consequently, at some point there will have to be transport of lipids within the cell where the lipids will need to be in solution. How is this facilitated? Like in the blood, intracellular lipid trafficking is facilitated by vesicular transport and lipid carriers like fatty acid binding proteins. In addition, intracellular membranes are densely packed and they can exchange lipids by collision and transient hemifusion. If you have access to Cell, a good review is from Prinz W. 2010 Lipid Trafficking sans vesicles, Where, Why, How?
The following is multiple choice question (with options) to answer.
The hemolymph and body cells exchange chemicals within what body part? | [
"the heart",
"the gums",
"the sinuses",
"the lungs"
] | C | |
SciQ | SciQ-3246 | bond
Title: Types of bonds in a molecule For example in dinitrogen pentoxide, $\ce{N2O5}$, covalent as well as coordinate bonds (type of covalent bonds) are present, but it appears that it contains only covalent bond.
What is a proper method to find out which type of bonds are present in a molecule? Electrovalent bonds are easiest to identify. If a compound is made up of a metal and non-metal/non-metallic radical (like carbonate), then, 99.99% times, it contains electovalent bond. If a compound is made up of 2 or more non-metals/non-metallic radicals, then it contains covalent bond. Coordinate covalent bonds appear mostly with compounds containing Hydrogen element. To identify the coordinate covalent bonds, you can draw the branched structural formula of the compound and see if the shared pair of electrons are coming from the same molecule.
The following is multiple choice question (with options) to answer.
Types of compounds include covalent and which other compounds? | [
"solvent",
"reactant",
"soluble",
"ionic"
] | D | Types of compounds include covalent and ionic compounds. They differ in the nature of the bonds that hold their atoms or ions together. |
SciQ | SciQ-3247 | biochemistry, medicinal-chemistry
Title: What makes a metal safe to use for an artificial joint? What determines if a metal is suitable for transplantation such as in the hip? What I am most interested in however is why might some metals be toxic to animals once in the body? There are a number of reasons why a given metal may be toxic to an animal:
Radioactive metals are the easy ones.
Some metals can affect the normal biosynthetic pathways within the body. Lead is a good example of this, as it can take the place of calcium; I believe beryllium does the same for magnesium.
Some metals themselves are very reactive. Hexavalent chromium ($Cr(VI)$) is highly reactive, and will cause damage through severe oxidative reactions, whereas $Cr(III)$ is largely okay.
A lot of metals are okay, even required, at some level, but become toxic at too high a concentration. Iron, for example.
People can simply have allergies to metals. Nickel in silver jewelry is a good example, although in my experience it can be overcome.
The basic gist is that some metals are required for life, some aren't but aren't too terrible, and some are completely toxic to it. Different organisms can vary a bit in which metals are useful or not. A good implant will of course not be toxic at all, and will be strong and long-lasting. Titanium is often used, given its strength and general nonreactiveness, but so is cobalt, despite being toxic to some degree.
Ref: Metal Sensitivity in Patients with Orthopaedic Implants. Hallab, et al. J Bone Joint Surg Am, 2001 Mar 01;83(3):428-428
The following is multiple choice question (with options) to answer.
Animals can transport what waste material in the circulatory system and store it safely at high concentrations? | [
"phosphorus",
"proteins",
"carbon",
"urea"
] | D | |
SciQ | SciQ-3248 | physiology
Title: How does a nerve cell adjust if O2 diffusion is interrupted? What effects would it have on a nerve if the oxygen supply is cut off? Is there any data on this?
Does the nerve conductance velocity increase? What about the Amplitude and receptor-channels on/in the nerve?
Funnily enough it's insanely hard to come by an answer to this question, or maybe I'm just searching at the wrong places.... If Oxygen diffusion is interrupted, there is a serious problem. Neurons inside of the brain slowly start to die, many other things like change in personality or the inability to process pain impulses occur if the brain is deprived of oxygen.If this is not fixed within 15 minutes it is impossible to survive.
The actual effects on the neurons are as follows:
Like in most cells the first solution to this kind of circumstance is anaerobic metabolism, the same happens in neurons but it does not last long and it is inefficient. As far as i'm concerned nerve conductance decreases in this kind of scenario and the receptors shrivel.
Well if the receptors are shriveling, they shouldn't be able to transfer impulses meaning that nerve conductance should stop.
This link to an article on the effects on the brain from oxygen deprivation.
https://www.livestrong.com/article/106179-effects-lack-oxygen-brain/
The following is multiple choice question (with options) to answer.
What can happen if there is a blockage in circulation to the brain? | [
"hydration",
"memory",
"stroke",
"automation"
] | C | Atherosclerosis normally begins in late childhood and is typically found in most major arteries. It does not usually have any early symptoms. Causes of atherosclerosis include a high-fat diet, high cholesterol, smoking, obesity, and diabetes. Atherosclerosis becomes a threat to health when the plaque buildup prevents blood circulation in the heart or the brain. A blocked blood vessel in the heart can cause a heart attack. Blockage of the circulation in the brain can cause a stroke. |
SciQ | SciQ-3249 | elasticity
Title: "Poynting vector" for transverse waves in elastic solid What is the expression or name for the vector that gives the direction and intensity associated with the energy flux or momentum flux carried by transverse waves in an elastic solid? I just learned that this is called the elastodynamic Pointing vector,
$$ \mathbf{S} = -\mathbf{v}\cdot \mathbf{T},$$
where $\mathbf v$ is the particle velocity and $\mathbf T$ is the stress tensor.
Source: C. Dean, Braselton in Theoretical and Computational Acoustics 2003, citing Auld, Acoustic fields and waves in solids, vol. I (1973).
For example, consider a purely transversal wave propagating along the $z$ axis, with the displacement along the $x$ axis. A volume element may have an instantaneous velocity $v$ in the $x$ direction. The stress tensor will describe $x$-$z$ shear stress. Then we would have
$$ \mathbf S = -(v, 0, 0) \cdot
\left( \begin{array}{ccc}
0 & 0 & \sigma_{xz} \\ 0 & 0 & 0 \\ \sigma_{zx} & 0 & 0
\end{array}\right)
=
(0, ~0, -v\sigma_{zx}).
$$
The following is multiple choice question (with options) to answer.
The high points of a transverse wave are called what? | [
"ridges",
"crests",
"valleys",
"points"
] | B | The high points of a transverse wave are called crests, and the low points are called troughs. |
SciQ | SciQ-3250 | climate-change, sea-level, glaciology, ice-sheets, antarctica
Title: Where does the biggest land-based ice cap reside? I'm thinking biggest in volume, regarding which area of the planet will contribute more to a raising in sea level - were the ice in those regions to melt.
I can basically think of two candidates, namely Greenland and Antarctica. So maybe some comparison between the contributions of the two would be great. Antarctica is the ice sheet (cap) that will contribute most IF it would melt completely. The 2013 IPCC report (Ch. 4, the Cryosphere) provides an estimate of 58.3 m of sea level equivalent (sle). Greenland would if completely wasted away provide 7.36 m sle. Remaining glaciers provide an additional 0.41 m sle. The likelihood of Antarctica completely wasting away seems unlikely with our current understanding although the so-called West Antarctic Ice sheet (closes to the Antarctic Penninsula is sitting with its base deep below the current sea level) is far more likely to be lost than the East Antarctic Ice Sheet. Hence the contribution from Antarctica is likely less than the maximum number. Greenland on the other hand is thought to have a "point of no return" beyond which it will irreversibly be lost given the current or warmer climate. Since Greenland is mostly land-based, much of the mass loss will be by surface melting while West-Antarctica can lose much of its mass by ice berg calving which is likely a much faster loss mechanism. Estimates on the scenarios are emerging but there are still uncertainties and there may also be feedbacks that we either do not fully understand or have not yet seen that can change these scenarios (particularly for West-Antarctica). This Science article
published online May 12 2014 is a good example of emerging research on the stability issues of West Antarctica.
The following is multiple choice question (with options) to answer.
Besides greenland, where are the earth's largest ice sheets found? | [
"Asia",
"antarctica",
"North America",
"Europe"
] | B | Nearly all glacial ice is in the polar regions. The largest ice sheets are in Antarctica and Greenland. The remaining 1% of Earth's ice is found elsewhere, like in the mountains, for example. At higher altitudes, temperatures are colder. Snow is more likely to fall and not melt. Except Australia, every continent has glaciers in the high mountains. |
SciQ | SciQ-3251 | electromagnetic-radiation
Title: Why EM waves lose energy via the square of distance but the light will not? Does that mean that EM propagate forever in vacuum? today at some class at the university we were taught about the propagation of EM (electromagnetic) waves and that they lose energy proportional to the square of distance. Then someone asked: "Why then the light propagate forever in outer space?"
And the professor answered: "Light is not electromagnetic wave so it won't lose energy, it's just described as an em." (like a mathematical model)
That answer left me speachless because as far as I know light is em. I would apreciate an answer from someone expert. By "Light", I assume you mean visible light. visible light is apart of the electromagnetic spectrum, and is itself, an electromagnetic wave.
An electromagnetic wave is a component of the electric and magnetic field, caused by the condition that: $$\frac{\partial \vec{J}}{\partial t} ≠ 0$$
When a charge accelerates, an electromagnetic wave is emmitted.
This wave consists of an electric component and a magnetic component
In the simplest form, for a point source of radiation
$\vec{E} \propto \frac{1}{r} $
$\vec{B} \propto \frac{1}{r} $
Meaning the strength of the Electric and magnetic field components decrease as the wave travels further away.
The poynting vector: $\vec{S} = \frac{1}{\mu_{0}} \vec{E} × \vec{B}$
Denotes the power radiated per unit area. Aka the rate of energy flowing as a result of the EM wave.
Meaning,
$\vec{S} \propto \frac{1}{r^2}$
There is an inverse square law for power radiated.
The rate at which energy flows is inversely proportional to the square of the distance from the source.
The total energy is constant however, as although the energy flow is less the further away you get, the energy is spread over a larger area.
The following is multiple choice question (with options) to answer.
What kind of path does the energy of an electromagnetic wave take? | [
"fluctuating",
"elliptical",
"circuitous",
"straight line"
] | D | The energy of an electromagnetic wave travels in a straight line along the path of the wave. The moving light wave has associated with it an oscillating electric field and an oscillating magnetic field. Scientists often represent the electromagnetic wave with the image below. |
SciQ | SciQ-3252 | atoms, phase
Title: What is the physical state of a single atom? Can a single atom on its own be either a solid, liquid, or a gas? Or is it none of them? This answer has been written so it hopefully can be understood by people that do not have a degree. If something is not correct, let me know, but be aware that throwing around fancy words will not help anyone understanding this any better. Consider the other posts here concerning liquids and solids, I don't want to be redundant and repeat what has been said already.
The answer is a bit complicated. One would intuitively say no, but that doesn't tell the whole story.
Take the interstellar medium. We have about 1 atom per cm³ in there and it is called a "gas". Now that's what I would call an isolated atom in the gas phase.
An atom is an object that belongs into the realms of quantum mechanics. A solid, liquid or gas is something that belongs into our classical world. If you zoom in close enough, that means if we look at a problem microscopically, words like "solid" or "liquid" no longer make sense. If you now begin to zoom out, the quantum effects vanish. This is sometimes called quantum decoherence and we enter the world of classical physics where solids and and liquids exist again.
So I would argue it all depends on how closely you look at the problem. Isolated atoms in a large volume? A gas if you ask me. But if you have to zoom in to talk about an individual atom within a larger compound consisting of many more atoms, let's say one atom within a piece of iron, you no longer can say that this single atom is "solid".
Think of it like this:
Can a single person have a political system?
The following is multiple choice question (with options) to answer.
The direct conversion of a solid to a gas, without an intervening liquid phase, is called what? | [
"amplification",
"isolation",
"insertion",
"sublimation"
] | D | The direct conversion of a solid to a gas, without an intervening liquid phase, is calledsublimation. The amount of energy required to sublime 1 mol of a pure solid is theenthalpy of sublimation (ΔHsub). Common substances that sublime at standard temperature and pressure (STP; 0°C, 1 atm) include CO2 (dry ice); iodine (Figure 11.18 "The Sublimation of Solid Iodine"); naphthalene, a substance used to protect woolen clothing against moths; and 1,4-dichlorobenzene. As shown in Figure 11.17 "The Three Phases of Matter and the Processes That Interconvert Them When the Temperature Is Changed", the enthalpy of sublimation of a substance is the sum of its enthalpies of fusion and vaporization provided all values are at the same T; this is an application of Hess’s law. (For more information about Hess’s law, see Chapter 5 "Energy Changes in Chemical Reactions", Section 5.2 "Enthalpy"). Equation 11.3. |
SciQ | SciQ-3253 | biochemistry, molecules, polymers, chemical-biology
A monomer is the simplest building block of a macromolecule with the properties of that macromolecule. They can be strung together to produce a macromolecule (usually by dehydration synthesis).
I would have no problem with these definitions if not for my teacher mentioning once that some monomers can also be macromolecules by themselves. Because some monomers of certain macromolecules- such as the monosaccharide glucose vs. the disaccharide sucrose or the polysaccharide amylose - can act on their own as an essential and functional carbohydrate, they are macromolecules by themselves.
Is this true? For example, could glucose be a macromolecule by itself?
Thanks. I can't think of an example where a biological monomer would be a macromolecule.
Definitions of macromolecule vary, usually by molecular weight or number of monomers (repeat units).
Personally, I'd go with ~1000 Dalton for a minimum, but the original definition of 1000 atoms is a good start too.
In any case, no biological monomer, including glucose will function the same as a macromolecule.
Consider starch - a macromolecule of sugars. It doesn't dissolve as quickly as simple sugar and has different physical properties.
Update
To clarify my comments.. Macromolecules or polymers are made up of monomers the way words are made up of letters. So no, a glucose molecule isn't really the same as a macromolecule, just like "R" is not a word.
Yes, macromolecules can be used to make larger assemblies like microtubules, filaments, etc., much the same way that words can form sentences and paragraphs.
In the polymer literature there's even the concept of a "macromonomer" referring to a monomer that is already large in size.
In my opinion though, the basic constituents (monomers) are still amino acids, nucleic acids, sugars, etc. These are not macromolecules.
The following is multiple choice question (with options) to answer.
Amino acids are the building blocks of what macromolecules? | [
"sugars",
"lipids",
"proteins",
"carbohydrates"
] | C | 3.4 Proteins Proteins are a class of macromolecules that perform a diverse range of functions for the cell. They help in metabolism by providing structural support and by acting as enzymes, carriers, or hormones. The building blocks of proteins (monomers) are amino acids. Each amino acid has a central carbon that is linked to an amino group, a carboxyl group, a hydrogen atom, and an R group or side chain. There are 20 commonly occurring amino acids, each of which differs in the R group. Each amino acid is linked to its neighbors by a peptide bond. A long chain of amino acids is known as a polypeptide. Proteins are organized at four levels: primary, secondary, tertiary, and (optional) quaternary. The primary structure is the unique sequence of amino acids. The local folding of the polypeptide to form structures such as the α helix and β-pleated sheet constitutes the secondary structure. The overall three-dimensional structure is the tertiary structure. When two or more polypeptides combine to form the complete protein structure, the configuration is known as the quaternary structure of a protein. Protein shape and function are intricately linked; any change in shape caused by changes in temperature or pH may lead to protein denaturation and a loss in function. |
SciQ | SciQ-3254 | forces, classical-mechanics, friction, torque
For me, if the force exerted on the tire by the ground is in the direction of motion, static friction will point backwards, opposing the eventual relative motion
If you gun the engine and the tire spins (or if you're on ice or something with minimal friction), it spins in a way where the bottom of the wheel moves backward (to the rear of the car) and the top of the wheel moves forward.
Friction creates forces that oppose relative motion. Since the wheel "wants" to move backward, that means that the friction force (on the tire) points forward. The relative motion we are talking about isn't between the car and the ground, it's between the bottom of the tire and the ground.
The following is multiple choice question (with options) to answer.
What force opposes a motion of a moving body? for example a car breaking on a road. | [
"friction",
"thermal",
"tension",
"vibration"
] | A | Friction is a force that opposes motion between any surfaces that are touching. Friction can work for or against us. For example, putting sand on an icy sidewalk increases friction so you are less likely to slip. On the other hand, too much friction between moving parts in a car engine can cause the parts to wear out. Other examples of friction are illustrated in the two Figures below and below . You can see an animation showing how friction opposes motion at this URL:. |
SciQ | SciQ-3255 | muscles
Title: What is meant by a muscle fiber being glycerinated? I was popped this questions today, "what is a glycerinated muscle fiber, and what is required for its contraction," and had little idea. I'm assuming the question is "what's required for its contraction as compared to normal muscle tissue?"
There's a limited amount of information out there about this. It appears that it is a type of in vitro system requiring special preparation of typical muscle tissue. I was wondering if anyone here had a little more information. Is this something that's just used in teaching lab exercises? From: http://www.acad.carleton.edu/curricular/BIOL/classes/bio126/Documents/Lab_5.pdf
Glycerination disrupts the membranes of the muscle cells, ruptures mitochondria, and leaches out soluble constituents such as ATP and inorganic ions. However, glycerinated muscle retains the organized structural array of myosin thick filaments and actin thin filaments, actin-associated proteins like troponin and tropomyosin which regulate contraction, and the functional capacity for contraction.
I would expect that because the sample has lost ATP and inorganic ions, you would need to supply ATP (the source of energy), $Mg^{2+}$ (which is necessary for ATP hydrolysis) and $Ca^{2+}$ (to induce the contraction).
The following is multiple choice question (with options) to answer.
The pain of angina means the heart muscle fibers need more what? | [
"nitrogen",
"carbon",
"oxygen",
"water"
] | C | Coronary heart disease often does not have any symptoms. A symptom of coronary heart disease is chest pain. Occasional chest pain can happen during times of stress or physical activity. The pain of angina means the heart muscle fibers need more oxygen than they are getting. Most people with coronary heart disease often have no symptoms for many years until they have a heart attack. |
SciQ | SciQ-3256 | 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.
Acids and bases are important in living things because what proteins typically can perform their job only at a certain level of acidity? | [
"enzymes",
"hormones",
"vitamins",
"catalysts"
] | A | Acids and bases are important in living things because most enzymes can do their job only at a certain level of acidity. Cells secrete acids and bases to maintain the proper pH for enzymes to work. For example, every time you digest food, acids and bases are at work in your digestive system. Consider the acidic environment of the stomach. The acidic environment helps with the digestion of food. The enzyme pepsin, which helps break down proteins in the stomach can only function optimally in the low pH environment. The stomach secretes a strong acid that allows pepsin to work, and the stomach to do its job. However, when stomach contents enter the small intestine, the acid must be neutralized. This is because enzymes in the small intestine need a basic environment in order to work. An organ called the pancreas secretes a strong base into the small intestine, and this base neutralizes the acid. |
SciQ | SciQ-3257 | cellular-respiration, fermentation
Fermentation: An ATP-generating process in which organic compounds act as both donors and acceptors of electrons. Fermentation can take place in the absence of O2. Discovered by Louis Pasteur, who described fermentation as “la vie sans l’air” (“life without air”).
So the biochemical lawyers have produced a definition that very few readers will be able to take in at first sight. What is this business about electron donors and acceptors? Well what it means in relation to the fermentation process in which lactic acid is produced (note my legalistic choice of words) is that one organic compound is reduced (glyceraldehyde 3-phosphate) — by NAD+ — and one organic compound is oxidized (pyruvate) — by NADH. And as the production of ATP is included in the definition this means that Berg et al. include glycolysis in this definition of fermentation.
…except that on the same page there is the following statement:
pyruvate is converted, or fermented, into lactic acid in lactic acid fermentation or into ethanol in alcoholic fermentation
So here it seems that the word is being used for the conversion of pyruvate to lactate or ethanol, i.e. it excludes glycolysis.
Pasteur managed to talk about fermentation without being aware of glycolysis or ATP, and it is clear to me that you can write whatever carefully phrased definitions you like, but people are going to continue to use venerable terms like fermentation in whatever way seems natual to them.
The following is multiple choice question (with options) to answer.
Cellular respiration that proceeds in the presence of oxygen is known as what? | [
"aerobic respiration",
"kinetic respiration",
"anaerobic respiration",
"digestive respiration"
] | A | Then, about 2 or 3 billion years ago, oxygen was gradually added to the atmosphere by early photosynthetic bacteria. After that, living things could use oxygen to break down glucose and make ATP. Today, most organisms make ATP with oxygen. They follow glycolysis with the Krebs cycle and electron transport to make more ATP than by glycolysis alone. Cellular respiration that proceeds in the presence of oxygen is called aerobic respiration . |
SciQ | SciQ-3258 | electromagnetic-radiation, wave-particle-duality
Title: The Feynman Lectures, behavior of electromagnetic spectra Its is mentioned that radio waves work as waves whereas X-rays behave like particles. What does it mean? Can someone elaborate it to a complete newbie.
Feynman Lectures
One of the consequences is that things which we used to consider as waves also behave like particles, and particles behave like waves; in fact everything behaves the same way. There is no distinction between a wave and a particle. So quantum mechanics unifies the idea of the field and its waves, and the particles, all into one. Now it is true that when the frequency is low, the field aspect of the phenomenon is more evident, or more useful as an approximate description in terms of everyday experiences. But as the frequency increases, the particle aspects of the phenomenon become more evident with the equipment with which we usually make the measurements. In fact, although we mentioned many frequencies, no phenomenon directly involving a frequency has yet been detected above approximately $10^{12} $ cycles per second.
Its is mentioned that radio waves work as waves whereas X-rays behave like particles. What does it mean? Can someone elaborate it to a complete newbie.
Electromagnetic radiation is described by the classical Maxwell's equations which are wave equations. They cover a whole frequency spectrum
The following is multiple choice question (with options) to answer.
Electromagnetic radiation behaves like particles as well as what? | [
"waves",
"currents",
"points",
"fluids"
] | A | Electromagnetic radiation behaves like particles as well as waves. This prompted Albert Einstein to develop his wave-particle theory. |
SciQ | SciQ-3259 | classical-mechanics
Title: Help me find flaws on my simple machines invention I have a work to make an invention on simple machines. First of all I am sorry if my English is not very good or clear. As we all know, simple machines are used to simplify things in life and use less work (mechanical advantage). My concept is using a pulley to pull things up, but I want to use like a machine that needs to be stepped (lever type 3) to move the pulley. But I feel like there is a flaw to my invention, and feel very frustated. This is my concept visualization:
P.S: Sorry for the language usage (Image is semi-English and semi-Indonesian language)
Thank you for the help. The idea of simple machines is usually "sacrifice length to gain force". Or the opposite, but more rarely. You have incorporated a level and pulleys in your design. Let's analyze those.
The lever
The first problem is that you have made a lever that, if you step on it, the weight will go down. But, it would already go down by gravity, this is not useful. You probably want to counteract gravity and make it go up, so something like this:
The other problem is the general idea of using a level with your foot. The thing is, you can't move your foot much. This means do not really have length to sacrifice to gain force. So, to use a lever with your foot, you have to either:
Use it to lift something very light with a single motion of the foot. It's hard to find a use for this, though. Also, it means that the edge of the lever would be really long a take much space.
Use it to lift a heavy weight, but your foot won't have enough room. To gain multiple times one floor's height, you'd probably want to jump from some roof:
Now that we got the lever "solved", let's discuss the pulley (which is much easier for you to do without being unrealistic).
Note that just having a pulley somewhere doesn't provide you an advantage. You have to use something like a snatch block:
This will indeed allow you to use a long rope to raise the weight with less effort:
The following is multiple choice question (with options) to answer.
Claw ends of hammers and flagpole pulleys are examples of simple machines that reverse what? | [
"direction of power",
"direction of friction",
"direction of work",
"direction of force"
] | D | Some machines change the direction of the force applied by the user. They may or may not also change the strength of the force or the distance over which the force is applied. Two examples of machines that work this way are the claw ends of hammers and flagpole pulleys. You can see in the Figure below how each of these machines works. In both cases, the direction of the force applied by the user is reversed by the machine. |
SciQ | SciQ-3260 | everyday-chemistry, biochemistry, food-chemistry, terminology
Vitamin D is not strictly a vitamin, rather it is the precursor of one
of the hormones involved in the maintenance of calcium homeostasis and
the regulation of cell proliferation and differentiation, where it has
both endocrine and paracrine actions.
The name vitamin D1 was originally given to the crude product of irradiation of ergosterol,
which contained a mixture of ergocalciferol with inactive lumisterol (an isomer of ergosterol) and suprasterols. When ergocalciferol was identified
as the active compound, it was called vitamin D2. Later, when cholecalciferol was identified as the compound formed in the skin and found in foods, it was
called vitaminD3.
Remarks
The "Vitamin B" naming of these compounds must have been through discovery, and no clear experiments had accurately produced identity of these compounds, there were named as they were discovered but since they have been identified they they now have systematic names
abeit vitamin B still being used today and are formulated as "vitamin B complexes" in pharmaceutical products (perhaps to avoid confusion) hence systematic names are used (folic acid, pantonthenic acid, biotin, thiamin, niacin, cobalamin etc) I have never come across complexes of other Vitamins. Remember for a compound to be named a vitamin it must fit the description above, but I am not disputing the fact that other compounds with similar biological activities exist as "K" group.
References
Nutritional Biochemistry of Vitamins (Bender)
Nutritional biochemistry (Brody)
Modern Nutrition in Health and Disease (Rosset al)
The following is multiple choice question (with options) to answer.
Lipids are also know by what name? | [
"proteins",
"fats",
"sugars",
"acids"
] | B | |
SciQ | SciQ-3261 | 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.
Roots, stems and leaves are organs commonly found in what? | [
"animals",
"fungi",
"algae",
"plants"
] | D | The three types of tissues work together in most plant organs. Three organs commonly found in modern plants are roots, stems, and leaves. |
SciQ | SciQ-3262 | virology, infection
Title: Why don't viruses cause wounds? A simple mental model of a viral infection is that an infected cell emits a lot of virions and eventually dies. The emitted virions have a chance of infecting other cells. Nearby cells are at a higher risk of infection.
Based on this model, if one cell in my nose gets infected, I would expect a large part of my nose to be destroyed, as the infection spreads and destroys more and more cells in the same area.
This does not happen! I survived a number of infections and still have my nose. Why?
I know there are "flesh eating" bacteria. Why isn't this the norm for infections? Does a common cold virus or SARS-CoV-2 not infect a lot of cells within the same area? A virus does not destroy that many cells before it is exterminated by the immune system or before the host dies.
Perhaps even more crucially, viruses typically target a very specific type of cell — those on the inner mucal surface of the nose in the case of cold or flu, those of the gastrointestinal tract in the case of stomach viruses, CD4 immune cells in the case of HIV, etc.
Update
As an example of how much time it takes for a virus to eat a noticeable wound, one could take the extermination of the immune cells by HIV - although it does not look as a physical wound, it is one, in the sense that enough of the specific tissue is destroyed to cause a life-threatening condition. It takes about a decade(!) - from the initial infection to the immune system failure.
On the other hand, the lethal effect of typical respiratory viruses is typically via obstructions of the respiratory ways due to inflammation or secretions resulting from the immune response, or via creating suitable conditions for a more serious bacterial infection.
The following is multiple choice question (with options) to answer.
What type of cells in the body fluids and tissues of most animals specifically interact with and destroy pathogens? | [
"Microglial cells",
"immune cells",
"White blood cells",
"Dendritic cells"
] | B | |
SciQ | SciQ-3263 | human-biology, cancer, systems-biology
Title: How does cancer of the larynx (laryngeal cancer) affect the respiratory system? The larynx is part of the respiratory system and is responsible for producing sound (our voices). My question is how cancer in the larynx (voice box) affect the respiratory system overall? I appreciate any answer, but if it's not too inconvenient, please don't use too complex terminology (I'm in grade 10 Canada).
Thanks According to this website:
http://www.spirometry.guru/fvc.html
it causes difficulty with inhalation but exhalation is normal...
"Typically the expiratory part of the F/V-loop is normal: the
obstruction is pushed outwards by the force of the expiration."
"During inspiration the obstruction is sucked into the trachea with
partial obstruction and flattening of the inspiratory part of the
flow-volume loop."
the exact symptoms of a laryngeal tumor depends on where it is located on the larynx... above the vocal cords, on the vocal cords, or below the vocal cords...
but more generally:
anatomy:
mouth/nose-->pharynx-->larynx-->trachea-->bronchi-->lungs
a tracheostomy may be necessary... basically the surgeon makes a connection between the skin outside the throat and the trachea... this bypasses the larynx (as well as pharynx and nose/mouth)...
The following is multiple choice question (with options) to answer.
What makes breathing difficult due to respiratory system disease? | [
"narrow air passages",
"water in the lungs",
"weak lungs",
"slippery air passages"
] | A | respiratory system disease in which air passages of the lungs periodically become too narrow, making breathing difficult. |
SciQ | SciQ-3264 | species-identification
Title: Identification of a lifeform There's a video I found on Facebook and I'm unable to figure out what the creature featured happens to be.
Adding images that have been taken from the video itself, apologies in advance since they're not high qualify images.
Can anybody shed any light on what it is?
The video was shot near Ratan Babu Ghat which is situated along the bank of Hooghly river, Kolkata, West Bengal, India. Here to be precise. This is a polyclad flatworm.
Here is a video of notoplana vitrea moving similarly to the one in the video that you linked:
https://www.asturnatura.com/especie/notoplana-vitrea.html
Here is a gallery of polyclad flatworms observed in India:
https://inaturalist.ca/observations?place_id=6681&subview=grid&taxon_id=52318
A number of the images in this gallery look similar to the one in your video, but very few of them are identified beyond this order taxon of polyclad flatworm.
The following is multiple choice question (with options) to answer.
What type of cell layer do flatworms have? | [
"mesoderm",
"endoderm",
"epidermis",
"cuticle"
] | A | Flatworms have a mesoderm cell layer and simple organ systems. They also show cephalization and bilateral symmetry. |
SciQ | SciQ-3265 | neuroscience, neuroanatomy
Title: Why is the anterior pituitary not considered part of the diencephalon? According to the wikipedia page on the diencephalon, the posterior pituitary gland is considered part of the diencephalon, but the anterior is not. Is there a reason that these two lobes of the same gland are considered different enough not to be part of the same brain region? Worth going to the wikipedia page on the pituitary:
In all animals, the fleshy, glandular anterior pituitary is distinct from the neural composition of the posterior pituitary, which is an extension of the hypothalamus.
The anterior pituitary arises from an invagination of the oral ectoderm (Rathke's pouch). This contrasts with the posterior pituitary, which originates from neuroectoderm.
The posterior lobe develops as an extension of the hypothalamus, from the floor of the third ventricle.
In other words, the different parts of the pituitary are, developmentally, entirely separate. The posterior lobe is actually part of the hypothalamus. The anterior lobe is not even part of the brain.
Lumping them together with one label happened because the anatomists who originally named the thing didn't know much about it, which is not surprising because anatomical names are quite old and understanding of the functions of any parts of the brain is quite new. Old names stick.
The following is multiple choice question (with options) to answer.
What gland is located at the base of the brain and secretes the hormone melatonin? | [
"thymus",
"pineal",
"thyroid",
"pituitary"
] | B | The pineal gland is a tiny gland located at the base of the brain. It secretes the hormone melatonin. This hormone controls sleep-wake cycles and several other processes. |
SciQ | SciQ-3266 | parasitology
Title: Tapeworms and their effect on humans I've read that some people in some countries actually use tapeworms as a form of losing weight. What are the dangers to these people? I haven't really found much on this topic (besides popular sites) but I can summarize it here:
There are quite some tapeworms (or cestoda), I found numbers of up to 3500 species. They attach to the intestinal wall of the humans and then start to take up predigested food through their skin. With that, they reduce food from their host and start to grow, some get as long as 15 meters!
Some of the worms seem to be relatively harmless (besides stealing food), but this is more true for the first world. In poor countries, where there is not enough food, tapeworms can cause severe malnutrition.
Some tapeworms can migrate into the blood stream and from there into other tissues or organs like muscles, eye and brain. There they can cause cysts which can lead to organ failure and death.
For more information see this CDC webpage and this article: "Biochemistry and physiology of tapeworms.". This popular article is probably also interesting.
The following is multiple choice question (with options) to answer.
What are the most common roundworm parasites of people in the u. s.? | [
"cutworms",
"hookworms",
"leeches",
"pinworms"
] | D | Tiny pinworms are the most common roundworm parasites of people in the U. S. In some areas, as many as one out of three children are infected. Humans become infected when they ingest the nearly microscopic pinworm eggs. The eggs hatch and develop into adults in the host’s digestive tract. Adults lay eggs that pass out of the host’s body to continue the cycle. Pinworms have a fairly simple life cycle with only one host. |
SciQ | SciQ-3267 | desert
Title: When was the first not-icy desert formed? For how long have deserts existed and which one would be the first to be created? I'm talking about arid, dry deserts, not the Antarctic or Arctic or any other icy deserts. Deserts have existed since at least the Permian period (299-251 million years ago) when the world's continents had combined into the Pangaea supercontinent. Stretching from pole to pole, this land mass was large enough that portions of its interior received little or no precipitation, according the University of California Museum of Paleontology.
Pangaea broke into smaller land masses which were moved across the surface by tectonic forces, a process that both changed global climate patterns and the climate those continents were exposed to. As a result, current desert regimes date back to no more than 65.5 million years, according to this Encyclopedia Britannica article:
The desert environments of the present are, in geologic terms,
relatively recent in origin. They represent the most extreme result of
the progressive cooling and consequent aridification of global
climates during the Cenozoic Era (65.5 million years ago to the
present), which also led to the development of savannas and scrublands
in the less arid regions near the tropical and temperate margins of
the developing deserts. It has been suggested that many typical modern
desert plant families, particularly those with an Asian centre of
diversity such as the chenopod and tamarisk families, first appeared
in the Miocene (23 to 5.3 million years ago), evolving in the salty,
drying environment of the disappearing Tethys Sea along what is now
the Mediterranean–Central Asian axis.
Which would put the oldest of "modern" desert somewhere in the region of what later became North Africa or South Asia.
The following is multiple choice question (with options) to answer.
What is the type of landscape that occurs at higher latitudes than deserts, has short grasses and low bushes, and are dry because they are in continental interiors? | [
"plains",
"plateau",
"steppe",
"tundra"
] | C | Other dry climates get a little more precipitation. They are called steppes . These regions have short grasses and low bushes ( Figure below ). Steppes occur at higher latitudes than deserts. They are dry because they are in continental interiors or rain shadows. |
SciQ | SciQ-3268 | quantum-mechanics, special-relativity, speed-of-light, heisenberg-uncertainty-principle
Title: Could the Heisenberg uncertainty principle be derived from the speed of light limit? Background:
As I was thinking about an alternative approach to the question: "why is there a finite speed of light, and why its magnitude corresponds to c?" –ultimately, I was trying to understand from which more fundamental theory could the electromagnetic permeability and permittivity of vacuum be derived from, as I share the view that only dimensionless constants are truly fundamental–, I felt on these papers (here and here) which seem to suggest that the speed of light is originated from the quantum properties of vacuum, more precisely, to the magnetization and polarization of fermion pairs in a quantum vacuum model. As far as I know, the existence of those short-lived (so-called) virtual particle pairs is made possible by the Heisenberg uncertainty principle (further reading).
I couldn't help but wonder if one could take the other way round, namely, if one could start from the special relativity principle which imposes c as the maximum speed of transmission of information/interaction and, by logical inference, find the necessity of an uncertainty principle which allows the existence of virtual particles pairs, that is, of quantum fluctuations in vacuum.
As I am relatively new to these subjects (I am still at the undergraduate level), and I suspect my reasoning to be in some way inconsistent, I would appreciate the opinion of any more knowledgeable person. Also, please excuse any misunderstanding of the underlying physics.
My question is, then:
Could this link between the uncertainty principle and the finite speed of light be envisageable? If it were, could it act as a conceptual connection between the principles of special relativity and quantum mechanics? If not, which logical problems would it encounter?
P.S.:
I also found this similar discussion on ResearchGate, which could be useful to anyone interested on answering this question. In Research Gate it is a very bad discussion mainly based on a couple of articles in a Journal on physics by a the Center for Innovative Research. The main editor seems to be someone doing microelectronics in India. To me the whole Center and the articles seem totally unreputable. If you can find a reputable scientific organization publishing anything like that Please refer to it. If not the best thing in my mind is to totally remove this reference.
The following is multiple choice question (with options) to answer.
The existence of (virtual) photons is possible only by virtue of the heisenberg uncertainty principle and can travel an unlimited distance, so the range ofthe electromagnetic for is what? | [
"finite",
"infinite",
"simple",
"generated"
] | B | CRITICAL THINKING QUESTIONS 19. How are neurons similar to other cells? How are they unique? 20. Multiple sclerosis causes demyelination of axons in the brain and spinal cord. Why is this problematic?. |
SciQ | SciQ-3269 | electricity, visible-light, waves
Title: Electromagnetic Waves We all know that light is an electro magnetic wave. but is electricity a EM wave? If it is then why light does not requires a medium to travel and why on the other side electricity needs a conductor ( I mean a medium) to travel. WHY? Or HOW? Electricity, understood as movement of electrical charges, can generate an EM-Wave, if the geometric conditions of the circuit and frequency conditions in the current flow are given.
As for the means to travel, it is interesting to refer to "skin effect." As the frequency of the current passing through a conductor is increased, the flow of electric charge moves to the outer surface of the conductor.
When the wavelength of the frequency associated with the movement of electric charges, it becomes comparable to the conductor length, the phenomenon of "radiation" is produced.
Ultimately, the movement of electric charge is normally performed in a conductive medium. If the specified conditions are met, this movement can generate an electromagnetic wave, which can propagate even in a vacuum.
So, electricity is not an electromagnetic wave, but can generate a disturbance in the associated electromagnetic field that has the ability to spread like a wave.
Something interesting to note is that an electromagnetic wave can generate electricity (photoelectric effect).
The following is multiple choice question (with options) to answer.
What is energy that travels in the form of an electromagnetic wave? | [
"light",
"gravity",
"sound",
"microwave"
] | A | Light is one type of electromagnetic radiation . Light is energy that travels in the form of an electromagnetic wave. Pictured below is a diagram of an electromagnetic wave ( Figure below ). An electromagnetic (EM) wave has two parts: an electric field and a magnetic field. The electric and magnetic fields vibrate up and down, which makes the wave. |
SciQ | SciQ-3270 | thermodynamics, water, phase-transition, evaporation, gas
Title: Why does water turn into water vapor? I read an article lately and it said that water turns into steam when it reaches its boiling point. But it led me to another question.
Why does water boil and why does the water turn into gas when it boils? Water molecules have attractive forces between them and form the liquid state.
First of all start with a container with water liquid and a vacuum above the water liquid.
This container and the water within it is kept at a constant temperature.
Some the water liquid molecules will have enough kinetic energy to overcome the attraction of their neighbouring water liquid molecules and escape from water liquid surface and become water vapour.
There is a net migration with water liquid molecules becoming water vapour molecules.
As time goes on and the number of water vapour molecules increases but some of those water vapour molecules will hit the water surface and become part of water liquid.
Eventually there are sufficient water vapour molecules and a dynamic equilibrium will be set up where the rate at which water liquid is converted into water vapour is exactly the same as the rate at which water vapour is converted into water liquid.
The pressure of the water vapour when this condition is satisfied is called the saturated vapour pressure.
Increasing the temperature means that the average kinetic energy of the water molecules increases and so the probability of a water liquid escaping from the surface of the liquid is increased.
So the rate at which water liquid turns to into water vapour increases.
For a time there is a net migration from water liquid to water vapour until the increase in the density of water vapour is sufficient for a new dynamic equilibrium to be set up.
The saturated vapour pressure increases as the temperature increases.
Raising the temperature will thus increase the saturated vapour pressure until there comes a temperature when the density of the vapour is the same as the density of the liquid.
The boundary (surface) between the liquid and the vapour disappears and you have just one phase.
That temperature is called the critical temperature and here is one video showing this effect.
Water liquid does not exist above the its critical temperature of $374\,^\circ \rm c$
The following is multiple choice question (with options) to answer.
What changes water vapor to liquid water? | [
"global warming",
"combustion",
"fermentation",
"condensation"
] | D | Condensation changes water vapor to liquid water. As air rises higher into the atmosphere, it cools. Cool air can hold less water vapor than warm air. So some of the water vapor condenses into water droplets. Water droplets may form clouds. |
SciQ | SciQ-3271 | mass, measurements
Title: How precise can current technologies measure the mass of an object? Masses of various objects are listed on this wikipedia page: Orders of magnitude (mass). For example, mass of an HIV-1 virus is on the order of 1 femtogram.
Are these data actually measured (which I really doubt), or calculated?
What is the most precise measurement technique we have to measure the mass of an object? The most precise measurement of the mass of an electron was reported by Sturm et al in Nature 506, 467–470 (27 February 2014), quoting a relative precision of $3\times 10^{-11}$, meaning they determined the mass to better than $3\times 10^{-41}~\rm{kg}$.
If that is not the best, at least it gives you an upper bound...
Note that if you could weigh such a small mass directly with scales on earth, the force would be equivalent to the gravitational pull of a mosquito (mass 2.5 mg) on a grain of sand (0.7 mg) at a distance of about 6 million kilometers - about 17 times the distance to the moon...
Astonishing.
Acknowledgement: CuriousOne's comment got me thinking about the measurement of the mass of the electron, and led me to the above analysis.
The following is multiple choice question (with options) to answer.
What instrument, with a digital readout, is used by scientists to measure very small masses? | [
"common balance",
"mixed balance",
"mechanical balance",
"electronic balance"
] | D | To measure very small masses, scientists use electronic balances, like the one in the Figure below . This type of balance also makes it easier to make accurate measurements because mass is shown as a digital readout. In the picture, the balance is being used to measure the mass of a white powder on a plastic weighing tray. The mass of the tray alone would have to be measured first and then subtracted from the mass of the tray and powder together. The difference between the two masses is the mass of the powder alone. |
SciQ | SciQ-3272 | nuclear-physics, radioactivity
Title: Carbon-14 formation in atmosphere Wikipedia says Carbon-14 is formed in the atmosphere by the reaction:
1n + 14N → 14C + 1p
This looks like neutron capture. However, I would expect neutron capture to result in 15N. However, "proton emission" seems to be a rare phenomenon:
15N → 14C + 1p
So, my first question is, does the reaction happen in two stages, or is the proton ejected "immediately"?
Secondly, is this overall type of reaction 1n + → + 1p common? Are there any other examples of such reactions, other than with 14N? It is a prompt (immediate) reaction, and is more usually written something like N14(n,p)C14 to indicate that. It is far from the only such reaction.
EDIT - To quantify my statement that there are many similar reactions, I went to the Evaluated Nuclear Data Files site hosted at Brookhaven (ENDF), entered 'n,p' for the reaction, 'sig' for the desired quantity (sig = sigma = cross-section in barns for the reaction). This returned 308 separate data sets, from He3(n,p)H3 to Bi209(n,p)Pb209. So, indeed, the existence of the N14(n,p)C14 reaction is no great surprise.
The following is multiple choice question (with options) to answer.
What element is released into the atmosphere by the burning of fossil fuels? | [
"sulfur",
"carbon",
"oxygen",
"helium"
] | A | water. Sulfur, critical to the 3–D folding of proteins (as in disulfide binding), is released into the atmosphere by the burning of fossil fuels, such as coal. The cycling of these elements is interconnected. For example, the movement of water is critical for the leaching of nitrogen and phosphate into rivers, lakes, and oceans. Furthermore, the ocean itself is a major reservoir for carbon. Thus, mineral nutrients are cycled, either rapidly or slowly, through the entire biosphere, from one living organism to another, and between the biotic and abiotic world. |
SciQ | SciQ-3273 | organic-chemistry, nomenclature, hydrocarbons
Title: Chain with double bond or triple bond
In this hydrocarbon there can be two main chains: one with two double bonds and one with a double and a triple bond
Both main chains contain seven carbon atoms.
Which will be considered correct and why? According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), as already mentioned in the question, the first relevant criterion to be considered in choosing a principal chain is the length of the chain.
When there is a choice for the principal chain, the following criteria are applied, in the order listed, until a decision is reached:
P-44.4.1 If the criteria of P-44.1 through P-44.3, where applicable, do not effect a choice of a senior parent structure, the following criteria are applied successively until there are no alternatives remaining. (…)
The senior ring, ring system, or principal chain:
(a) has the greater number of multiple bonds (P-44.4.1.1);
(b) has the greater number of double bonds (P-44.4.1.2);
(…)
(h) has the lower locant for an attached group expressed as a suffix (P-44.4.1.8);
(…)
Since both possible chains in this case have two multiple bonds, Rule (a) is not enough to make a choice.
According to Rule (b), the principal chain is the hepta-1,6-diene because it has the greater number of double bonds.
Therefore, the preferred IUPAC name (PIN) is 4-(prop-2-yn-1-yl)hepta-1,6-diene.
The following is multiple choice question (with options) to answer.
What type of hydrocarbons contain at least one double or triple bond between carbon atoms? | [
"ionic",
"saturated",
"catalytic",
"unsaturated"
] | D | Unsaturated hydrocarbons contain at least one double or triple bond between carbon atoms. As a result, the carbon atoms are unable to bond with as many hydrogen atoms as they would if they were joined only by single bonds. This makes them unsaturated with hydrogen. Unsaturated hydrocarbons are classified on the basis of their bonds as alkenes, alkynes, or aromatic hydrocarbons. |
SciQ | SciQ-3274 | waves
Title: Is wave motion the combined motion of the disturbance and the medium? Using a textbook slinky as an example, if the disturbance propagates through the slinky from left to right and the particles of the slinky vibrate up and down, does that mean 'wave motion' is also associated with the medium? Since the motion of the wave that we perceive is the combined motion of the disturbance and the medium? This answer is maybe not the most straightforward satisfactory answer to your stated question, but I think it anticipates ways of thinking that are used in more advanced areas of physics.
There are two pictures of what a wave is.
A wave is coherent motion in a medium; as time progresses energy moves through the medium and vibrations occur in different locations.
A wave is a propagating disturbance. It is not made of anything, the word "wave" refers a disturbance which propagates energy from one place to another.
Your question kind of implies that a wave is some combination of 1 and 2. I would say that either 1 or 2 are valid pictures, but you should treat them as distinct pictures of the same physical phenomenon and not reason about both simultaneously.
The advantage of the first picture is that it gives you a clear mechanical model of what is going on at a fundamental level; if you zoom in there are particles in the material, and the particles are oscillating back and forth in tandem -- that coherent motion is a wave. However, the disadvantage is that wave phenomena occur in many circumstances, and there are features of any particular example that will not generalize and can lead you astray if you take them too seriously. For example, light traveling in vacuum cannot be accurately visualized as motion of particles.
The advantage of the second picture is that it is more abstract and general -- wave phenomena occur in all kinds of materials, and so there is no need to specify which specific material you are thinking of, because we can make very general statements about waves that apply to any material. The disadvantage is that it can be hard to wrap your head around a disturbance without a medium, and also sometimes trying to be too general means you miss special aspects of the particular situation you might be interested in (for example, cool behavior like solitons can occur in water but not in light propagating in vacuum).
The following is multiple choice question (with options) to answer.
What is the general name for a wave that travels along the surface of a medium? | [
"light wave",
"stack wave",
"speed wave",
"surface wave"
] | D | A surface wave is a wave that travels along the surface of a medium. The medium is the matter through which the wave travels. Ocean waves are the best-known examples of surface waves. They travel on the surface of the water between the ocean and the air. |
SciQ | SciQ-3275 | human-biology, biochemistry, metabolism, food
Which seem to go in different, rather contradictory directions.
Also, Studies partially supporting either viewpoint can be found:
Study considering hemoglobin A1c levels
Study considering peak glucose levels
Study considering snacking
Which leaves the non-biologist asking themselves which is the "major effect" (certainly, there will be some truth to each position, but the question is which one(s) got the "main point"), and if there are any other important effects to be considered, hence this broad question here, so I understand, from a biological standpoint, what happens to the carbohydrates when I eat them, so I can conclude for myself how to adapt my diet for "optimal" health. Scope of Answer
The original poster provided ample context for his question, which related to health considerations. It was perhaps for this reason, among others, that the question had not received an answer at the time of writing: questions relating to medical or health advice are off-topic here. However, his actual question is primarily biochemical:
What are the biological differences between the digestion of sugar and
different types of carbs as constituents of different types of food in
humans?
Although this might be answered with a little internet search, I felt it would be hospitable if someone offered him an answer to this — and this only.
Definitions
The basic sugar unit is a mono-saccharide, those of relevance to this question being hexoses or pentoses, having six or five carbon atoms, respectively.
What in non-technical language is called sugar, refers to a specific molecule, sucrose, which is a disaccharide of covalently-bonded glucose and fructose.
What in non-technical language are referred to as dietary carbohydrates generally refers to the storage polysaccharide of plants such as potato and other root vegetables, rice, and other cereal crops used to make bread. This is a homo-polymer composed solely of glucose units.
Summary of the differences in metabolism
Arising from these definitions, the following differences in metabolism emerge:
Different enzymes (amylase for these polysaccharides, sucrase for saccharose) are used to catalyse the hydrolysis of the linkages between the monomeric units.
Absorption in the gut is different for glucose and fructose, as is transport into cells.
The following is multiple choice question (with options) to answer.
Carbohydrates are an important group of biological molecules that includes sugars and these? | [
"proteins",
"starches",
"vitamins",
"fats"
] | B | Carbohydrates are an important group of biological molecules that includes sugars and starches. |
SciQ | SciQ-3276 | biochemistry, neuroscience, pharmacology, toxicology, literature
The endogenous cannabinoid system is sensitive to contact with exogenous cannabinoids such as the delta-9-THC, which is known to impair memory in humans.
In a further study is was examined what impact chronic cannabis use has on memory-related functions by examination of the subsequent memory effect (SME) of the event-related potential (ERP). The study concluded that comparing the group to the control group that chronic users of cannabis have an altered memory related brain activation in the form of dysfunctional SME production which may also go hand in hand with reduced neural efficiency.
Several investigators studied the acute effects of cannabis specifically on attentional processing. Hart et al. (2001) studied the effects of placebo, light (1.8%), and heavy (3.9%) THC cigarettes in chronic, daily cannabis users and found no significant differences in the accuracy of response to attentional tasks. However, performance on a tracking task, which requires sustained attention, was found to improve significantly after the high dose of THC, relative to the other conditions.
In one study of 37 adults with a history of light cannabis use, acute intoxication with a high dose of THC resulted in significant impairment on a measure of impulsivity (McDonald et al., 2003). Another study (Ramaekers et al., 2006) found similar impairment on a task of inhibition in intoxicated, chronic cannabis users. The results measured where in a timespan from 0-6 hours after consumption.
In another study from 2010, researchers investigated "semantic-priming".
The following is multiple choice question (with options) to answer.
What types of drugs affect the brain and influence how a person can feel, think, or act? | [
"analgesics",
"antibiotics",
"prescription",
"psychoactive"
] | D | Many drugs affect the brain and influence how a person feels, thinks, or acts. Such drugs are called psychoactive drugs. They include legal drugs such as caffeine and alcohol, as well as illegal drugs such as cocaine and heroin. They also include certain medicines, such as antidepressant drugs and medical marijuana. |
SciQ | SciQ-3277 | physical-chemistry, reaction-mechanism, free-energy
How does it come, that in one case the activity of the whole product AB is important and in another the single activities of the components of the product?
Equation (1) refers to a molar free energy of formation of $\ce{AB}$ from reagents $A$ and $B$, all under the same constant (P,T, composition) conditions, whereas (2) refers to the free energy of formation of a solid solution of $n_A$ moles of A and $n_B$ moles of B from pure components. Equation (1) refers to combination of A and B at a 1:1 mole ratio, or equivalently reaction to form 1 mole of $\ce{AB}$ from $n_A=n_B=\pu{1 mol}$. Reaction (2) refers to mixture of A and B at any arbitrary ratio or total number of moles. Therefore equation (2) is in a way more general. Also, equation (1) refers to a differential process (transformation to form 1 mole of product under contant conditions) whereas (2) refers to an integral (mixing) process.
For the given reaction:
$$\Delta G = \Delta G^⦵ + RT\ln{\frac{a_\ce{AB}}{a_\ce{A}\cdot a_\ce{B}}} $$
Since all components are pure solid substances, all activities equal 1 and therefore, $\Delta G = \Delta G^⦵$.
The following is multiple choice question (with options) to answer.
Chemical reactions always involve what? | [
"physical change",
"energy",
"heating",
"fuel"
] | B | Chemical reactions always involve energy. Energy is a property of matter that is defined as the ability to do work. When methane burns, for example, it releases energy in the form of heat and light. Other chemical reactions absorb energy rather than release it. |
SciQ | SciQ-3278 | newtonian-mechanics, kinematics, centripetal-force
$\ddot{r} \hat{\bf r}$ radial acceleration owing to motion in the radial direction
$- \frac{v_\theta^2}{r} \hat{\bf r}$ the centripetal acceleration which causes any transverse velocity to change direction (and thus follow a circle if the other terms were absent)
$r \ddot{\theta} \hat{\boldsymbol \theta}$ acceleration around a circle associated with second derivative of the angle.
$2 \dot{r} \dot{\theta} \hat{\boldsymbol \theta}$
the Coriolis acceleration, which is present only when both $r$ and $\theta$ are changing.
Three dimensions
At any point on a trajectory you can define a plane singled out by the velocity and acceleration vectors. In that plane you can set up rectangular coordinates and polar coordinates in two dimensions, and then the above formulae apply.
The following is multiple choice question (with options) to answer.
An object undergoing circular motion experiences centripetal what? | [
"vibration",
"transmission",
"velocity",
"acceleration"
] | D | Linear or tangential acceleration refers to changes in the magnitude of velocity but not its direction. We know from Uniform Circular Motion and Gravitation that in circular motion centripetal acceleration, a c , refers to changes in the direction of the velocity but not its magnitude. An object undergoing circular motion experiences centripetal acceleration, as seen in Figure 10.5. Thus, a t and a c are perpendicular and independent of one another. Tangential acceleration a t is directly related to the angular acceleration. |
SciQ | SciQ-3279 | geology, sedimentology
Title: Is Desert Sandstone a chemical sedimentary rock? I gather that chemical sedimentary rocks are formed when minerals in solution are supersaturated and therefore they precipitate out.
I also understand that desert sandstone is formed as Iron Oxide rich water evaporates leaving a hematite cement.
Does this mean Desert Sandstone is a chemical sedimentary rocks? No, it's not.
The overwhelming majority of the material in the rock is clastic, not chemical. Chemical sedimentary rocks are rocks where (almost) all of the material was precipitated, such as travertine, evaporites, etc.
Cementation is a chemical process. As a clastic sedimentary rock has to be cemented somehow, otherwise it would be a sediment rather than a rock, all clastic sedimentary rocks have undergone some chemical process. This does not mean that they are chemical though.
As diagenesis progresses and the rock undergoes more chemical changes it may become a diagenetic clastic sedimentary rock of even a metamorphic one, but never a chemical sedimentary rock. This implies that most, if not all, of its initial mass precipitated out of solution.
The following is multiple choice question (with options) to answer.
What rocks are formed by crystallization of chemical precipitates? | [
"chemical sedimentary",
"layered",
"volcanic",
"carbon sedimentary"
] | A | Sedimentary rocks formed by the crystallization of chemical precipitates are called chemical sedimentary rocks . Dissolved ions in fluids precipitate out of the fluid and settle out, just like the halite pictured below ( Figure below ). |
SciQ | SciQ-3280 | botany, plant-physiology, plant-anatomy
Title: Sporophyte and gametophyte
My textbook says that in both groups of seedless plants (vascular plants, non-vascular plants) the gametophyte is a free-living plant, independent of the sporophyte.
I don't understand this statement and am now wondering if the sporophyte and gametophyte are stages in a plant's lifecycle, or are they individual parts of the plant, or are the sporophyte and the gametophyte different plants altogether? Secondly, does this differ depending on the organism?
Different plants or different structures that make up the same organism? The sporophtye is the diploid stage in the life cycle. In comparison, with humans, you and I would be sporophytes.
The Gametophyte is the haploid stage in the life cycle. In comparison, with humans, spermatozoids and ovules are gametophytes.
The following is multiple choice question (with options) to answer.
In some plants, the sporophyte is diploid, while the gametophyte is what? | [
"meiosis",
"gametes",
"humanoid",
"haploid"
] | D | The sporophyte produces haploid spores. The rhizoid buds to form a mature gametophyte. The zygote is housed in the venter. Figure 25.21 Which of the following statements about the fern life cycle is false? a. Sporangia produce haploid spores. The sporophyte grows from a gametophyte. The sporophyte is diploid and the gametophyte is haploid. Sporangia form on the underside of the gametophyte. |
SciQ | SciQ-3281 | cell-biology, molecular-biology
Title: Intracellular lipid transport I know that lipids are carried around the body in the blood either as micelles or by lipid-binding proteins which allow them to be solved.
Lipids can't always be integrated in a membrane though, the phospholipids used in membranes have to be synthesised somewhere from a precursor which will also by hydrophobic.
Consequently, at some point there will have to be transport of lipids within the cell where the lipids will need to be in solution. How is this facilitated? Like in the blood, intracellular lipid trafficking is facilitated by vesicular transport and lipid carriers like fatty acid binding proteins. In addition, intracellular membranes are densely packed and they can exchange lipids by collision and transient hemifusion. If you have access to Cell, a good review is from Prinz W. 2010 Lipid Trafficking sans vesicles, Where, Why, How?
The following is multiple choice question (with options) to answer.
A lipid is one of a highly diverse group of compounds made up mostly of what? | [
"amines",
"proteins",
"nucleic acid",
"hydrocarbons"
] | D | Lipids A lipid is one of a highly diverse group of compounds made up mostly of hydrocarbons. The few oxygen atoms they contain are often at the periphery of the molecule. Their nonpolar hydrocarbons make all lipids hydrophobic. In water, lipids do not form a true solution, but they may form an emulsion, which is the term for a mixture of solutions that do not mix well. |
SciQ | SciQ-3282 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
During mitosis what is replicated in the primary spermatocyte? | [
"rna",
"oocyte",
"mitochondira",
"dna"
] | D | Two identical diploid cells result from spermatogonia mitosis. One of these cells remains a spermatogonium, and the other becomes a primary spermatocyte, the next stage in the process of spermatogenesis. As in mitosis, DNA is replicated in a primary spermatocyte, and the cell undergoes cell division to produce two cells with identical chromosomes. Each of these is a secondary spermatocyte. Now a second round of cell division occurs in both of the secondary spermatocytes, separating the chromosome pairs. This second meiotic division results in a total of four cells with only half of the number of chromosomes. Each of these new cells is a spermatid. Although haploid, early spermatids look very similar to cells in the earlier stages of spermatogenesis, with a round shape, central nucleus, and large amount of cytoplasm. A process called spermiogenesis transforms these early spermatids, reducing the cytoplasm, and beginning the formation of the parts of a true sperm. The fifth stage of germ cell formation—spermatozoa, or formed sperm—is the end result of this process, which occurs in the portion of the tubule nearest the lumen. Eventually, the sperm are released into the lumen and are moved along a series of ducts in the testis toward a structure called the epididymis for the next step of sperm maturation. |
SciQ | SciQ-3283 | neuroscience
Title: Nervous system : Nerve signals If the electrical signals from all the various organs throughout the body eventually connect to the nerves in the spinal column traveling up to the brain, how does the brain differentiate the different signals. Is the nerve in the spinal column like an electrical conduit with many wires inside? Yes is the simple answer. A nerve will go up to a specific part of the brain which the brain knows corresponds to a certain region of the body. It isn't perfect though e.g. pain in the diaphragm confuses the brain which doesn't recognise that pain must be coming from there so instead tells the body there is shoulder pain, however this is useful in medicine. Another infamous example is pain from heart disease (angina) which causes pain in the jaw and arm. Perhaps even more interestingly, if a nerve is cut and then grows back linking to the wrong nerve it may lead to the completely wrong part of the body being identified when touched. Also if the brain itself is stimulated in these corresponding areas, a person will feel he or she is indeed being touched in a certain part of the body.
The following is multiple choice question (with options) to answer.
What can carry nerve impulses from tissues and organs to the spinal cord and brain? | [
"healthy neurons",
"respiratory neurons",
"motor neurons",
"sensory neurons"
] | D | Sensory neurons carry nerve impulses from tissues and organs to the spinal cord and brain. |
SciQ | SciQ-3284 | At some point, all work needs a public airing to improve. That time for me is now. Thank you in advance on behalf of my students for any feedback.
## Chemistry, CAS, and Balancing Equations
Here’ s a cool application of linear equations I first encountered about 20 years ago working with chemistry colleague Penney Sconzo at my former school in Atlanta, GA. Many students struggle early in their first chemistry classes with balancing equations. Thinking about these as generalized systems of linear equations gives a universal approach to balancing chemical equations, including ionic equations.
This idea makes a brilliant connection if you teach algebra 2 students concurrently enrolled in chemistry, or vice versa.
FROM CHEMISTRY TO ALGEBRA
Consider burning ethanol. The chemical combination of ethanol and oxygen, creating carbon dioxide and water:
$C_2H_6O+3O_2 \longrightarrow 2CO_2+3H_2O$ (1)
But what if you didn’t know that 1 molecule of ethanol combined with 3 molecules of oxygen gas to create 2 molecules of carbon dioxide and 3 molecules of water? This specific set coefficients (or multiples of the set) exist for this reaction because of the Law of Conservation of Matter. While elements may rearrange in a chemical reaction, they do not become something else. So how do you determine the unknown coefficients of a generic chemical reaction?
Using the ethanol example, assume you started with
$wC_2H_6O+xO_2 \longrightarrow yCO_2+zH_2O$ (2)
for some unknown values of w, x, y, and z. Conservation of Matter guarantees that the amount of carbon, hydrogen, and oxygen are the same before and after the reaction. Tallying the amount of each element on each side of the equation gives three linear equations:
Carbon: $2w=y$
Hydrogen: $6w=2z$
Oxygen: $w+2x=2y+z$
where the coefficients come from the subscripts within the compound notations. As one example, the carbon subscript in ethanol ( $C_2H_6O$ ) is 2, indicating two carbon atoms in each ethanol molecule. There must have been 2w carbon atoms in the w ethanol molecules.
The following is multiple choice question (with options) to answer.
Chemical equations need to be balanced to satisfy the law of what? | [
"conservation of matter",
"glow of matter",
"speed of matter",
"material of matter"
] | A | Chemical equations need to be balanced to satisfy the law of conservation of matter. |
SciQ | SciQ-3285 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
Which species in class insecta has three body segments, six jointed legs, and multiple head appendages? | [
"sauropod",
"arthropod",
"mollusc",
"arachnid"
] | B | arthropod in Class Insecta that has three body segments, six jointed legs, and multiple head appendages. |
SciQ | SciQ-3286 | genetics
Additional response added as requested:
I see what you are getting at - why do children seem like such individual and unique things sometimes?
In sexual reproduction, the offspring are the product of the shuffling of the parent's genomes through meiosis, where the pairs of chromosomes we have are combined to make a single chromosome that will be half of the children genome.
This process can result in completely novel combinations of genes while conveying many likenesses from the parent. I would guesstimate that this is the major cause of the uniqueness of offspring/children.
Also in mammals there are some cell lines which splice families of genes which will cause offspring to be potentially quite different from either parent. Immune genes for instance are created from scratch from a bunch of genes that the parents give. Making each offspring unique but also the product of the parent's genetic repertoire. This can be significant as it affects health and also to some extent attraction - studies have shown that people who smell attractive to us are immunologically distinct from us.
@David mentions epigenetic variation, which is a more recent significant development. During our life, the germline (sperm/egg) DNA may be chemically labelled depending upon environmental conditions we experience. A famous example is experiencing famine conditions, which caused the children to be born on the small side amongst other effects. More recent studies have shown that this is a widespread mechanism to control cells in our body during our lifetime as well as communicate to our offspring how life is. It is expected that this labeling does not affect us forever - the epigenetic labels change over the course of a generation quite often (we believe).
The following is multiple choice question (with options) to answer.
Whether it's puppies or people, offspring and parents usually share many of what? | [
"traits",
"clothes",
"fruits",
"insects"
] | A | People have long known that offspring are similar to their parents. Whether it's puppies or people, offspring and parents usually share many traits. However, before Gregor Mendel's research, people didn't know how parents pass traits to their offspring. |
SciQ | SciQ-3287 | volcanology, volcanic-hazard, volcanic-eruption
Title: Would a Yellowstone eruption destroy global agriculture? Someone recently claimed in my hearing that if the Yellowstone caldera were to erupt, the resulting ash cloud would end all agriculture for a year or two. (The speaker is not a scientist, and neither am I.)
Is that accurate?
Are there reasonable scenarios (i.e., not this) worked out for the effects of a supervolcano eruption?
I did see this question, where one of the commenters points out that such an event would be unprecedented, so our ability to predict is limited, but I'm still curious about whatever we do know at this stage. An eruption of the Yellowstone super volcano would cause agricultural disaster over a very large area. Its global effect would be significant, but not totally devastating.
The resulting climate cooling could last up to a decade. The temporary climate shift could alter rainfall patterns, and, along with severe frosts, cause widespread crop losses and famine.
But a Yellowstone megablast would not wipe out life on Earth. There were no extinctions after its last three enormous eruptions, nor have other supereruptions triggered extinctions in the last few million years.
Eruption of super volcanoes is rare which makes it difficult to ascertain what exactly would happen when the Yellowstone super volcano eventually erupts - which won't be any time soon.
Yellowstone last erupted 174 000 years ago, which was a minor eruption. Lava from Yellowstone won't be the problem, but the ash and gases will be.
The last major eruption, 630 000 years ago, covered much of western and central United States with ash. The maximum thickness of the ash from that eruption is 660 ft. The eruption was a double eruption, 170 years apart. The amount of ash thrown into the atmosphere with each eruption caused the ocean to cool by 3 degrees Celsius with each eruption.
The following is multiple choice question (with options) to answer.
Connected to agriculture, forestry, mining, and urbanization, what is the single biggest cause of extinction today? | [
"freshwater loss",
"global warming",
"habitat loss",
"hunting"
] | C | The single biggest cause of extinction today is habitat loss . Agriculture, forestry, mining, and urbanization have disturbed or destroyed more than half of Earth’s land area. In the U. S. , for example, more than 99 percent of tall-grass prairies have been lost. Other causes of extinction today include:. |
SciQ | SciQ-3288 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
The hexapoda subphylum includes mainly what type of animal? | [
"birds",
"mammals",
"spiders",
"insects"
] | D | Living arthropods are divided into four subphyla. They are described in Table below . The Hexapoda subphylum includes mainly insects. There are so many insects and they are so important that they are described in greater detail below. |
SciQ | SciQ-3289 | zoology, terminology, nomenclature, invertebrates, etymology
Urochorda
Cephalochorda
Craniata
which is more or less the accepted division today, with Urochorda being called Urochordata now.
In this essay, Lankester says:
The evidence of degeneration is admitted as conclusive in the case of the parasitic Crustacea and Cirrhipedes. It is equally incontestable in that very large and varied group of non-parasitic organisms, the Tunicata (Urochordate Vertebrata).2
(in the above 'Vertebrata' is what we call 'Chordata'). He adds this footnote:
2The whole argument as to the Tunicates of course rests on the view- supported by many arguments, that the larval urochord, which many of
them possess, is not a larval organ acquired by larval adaptation, but is hereditary and transmitted from adult ancestors.
The term 'urochord' seems to be established and used without comment there, and probably is taken as simple neo-Latin for 'tail chord', although that may be somewhat loose, perhaps meaning the notochord is present but does not extend into the head. A 1913 Webster's Dictionary defines urochord as:
(Zool.) The central axis or cord in the tail of larval ascidians and of certain adult tunicates.
In 1882, Lankester futher discussed the anatomy of the tunicates in the context of the division of the chordata in a paper called "The Vertebration of the Tail of Appendiculariæ". This paper includes an illustration of a larval tunicate with the "notochord (urochord)" indicated.
The following is multiple choice question (with options) to answer.
What are living echinoderms divided into five of? | [
"clades",
"species",
"sexes",
"classifications"
] | A | |
SciQ | SciQ-3290 | solar-system, comets
Title: How does a comet form? As the title explains,
How does a comet form?
What are the elements, what is a comet composed of?
Why didn't they become part of planets, moons or asteroids?
Comets are some of the material left over from the formation of the planets. Our entire solar system, including comets, was created by the collapse of a giant, diffuse cloud of gas and dust about 4.6 billion years ago. Much of the matter merged into planets, but some remained to form small lumps of frozen gas and dust in the outer region of the solar system, where temperatures were cold enough to produce ice.
A comet is generally considered to consist of a small nucleus embedded in a nebulous disk called the coma. the nucleus, containing practically all the mass of the comet, is a “dirty snowball” conglomerate of ices and dust.For one, of the observed gases and meteoric particles that are ejected to provide the coma and tails of comets, most of the gases are fragmentary molecules, or radicals, of the most common elements in space: hydrogen, carbon, nitrogen, and oxygen. The radicals, for example, of CH, NH, and OH may be broken away from the stable molecules CH4 (methane), NH3 (ammonia), and H2O (water), which may exist as ices or more complex, very cold compounds in the nucleus.
3.Many astronomers believe that these small objects never became planets or other large objects because of the gravity of the large planets. For example, the pull of Jupiter's kept 'stirring the pot' of the asteroid belt, so that the gravitational pull of the asteroids on each other was constantly being disturbed.
For the Kuiper belt and Oort cloud, there is a popular theory called 'planetary migration.' The main idea behind this theory is that the large outer planets of our Solar System started out much closer to the Sun when the Solar System was formed. As they migrated outward through the cloud of small objects still there, the gravity of these large planets pulled a lot of the small objectsout of their orbits. Some were pulled into the planets, and some were flung far into the outer reaches of the Solar System.
The objects that were flung very far out by Jupiter became the Oort cloud. The object that were not flung out quite as far by the movement of Neptune became the Kuiper belt.
Source
The following is multiple choice question (with options) to answer.
Gases on earth originated from comets and what events? | [
"tides",
"black holes",
"supernovas",
"volcanic eruptions"
] | D | The earliest Earth did not have an atmosphere or free water. The planet was far too hot for gases and water to collect. The atmosphere and oceans that we see today evolved over time. The gases came from volcanic eruptions and from comets. |
SciQ | SciQ-3291 | the-sun, solar-system, earth, temperature, weather
That Wikipedia quote mentioned that "change in day length is another factor". I have some info and graphs about that here.
The distance from the Earth to the Sun does have an effect on the climate, but it's fairly minor. Currently, the Earth is closest to the Sun (perihelion) in early January, around 10 days after the December solstice, during the northern hemisphere winter and southern hemisphere summer. That makes the southern summer a bit hotter than the northern summer. It also makes the southern summer a bit shorter, because the orbital speed is fastest near the perihelion. However, the climate in the southern hemisphere is strongly affected by the strong circumpolar ocean current around Antarctica, which keeps the southern oceans cold all year round. In the southern hemisphere, not many people live at higher latitudes than 40° because it's just too cold, but that latitude in the northern hemisphere is quite heavily populated.
I have some info about the perihelion here and here.
For what it's worth, here's a graph of the distance from the Earth to Sun and to the SSB, for 2022, with a 7 day timestep between the data points.
Plotting script from https://astronomy.stackexchange.com/a/49823/16685
Here's a plot spanning 1700 to 2200 (the same timespan as my Sun-SSB plot in the answer linked above), also with a 7 day timestep.
The following is multiple choice question (with options) to answer.
What season is it in the southern hemisphere when it's winter in the northern? | [
"Spring",
"Winter",
"summer",
"autumn"
] | C | Winter solstice for the Northern Hemisphere happens on December 21 or 22. The North Pole of Earth's axis points away from the Sun ( Figure below ). Light from the Sun is spread out over a larger area. With fewer daylight hours in winter, there is also less time for the Sun to warm the area. When it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere. |
SciQ | SciQ-3292 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
What is the name for areas where there is overlap between closely related species? | [
"gap zones",
"extinction zones",
"mono zones",
"hybrid zones"
] | D | 18.3 Reconnection and Rates of Speciation Speciation is not a precise division: overlap between closely related species can occur in areas called hybrid zones. Organisms reproduce with other similar organisms. The fitness of these hybrid offspring can affect the evolutionary path of the two species. Scientists propose two models for the rate of speciation: one model illustrates how a species can change slowly over time; the other model demonstrates how change can occur quickly from a parent generation to a new species. Both models continue to follow the patterns of natural selection. |
SciQ | SciQ-3293 | human-biology, human-anatomy, human-physiology
Title: How can we move our lips even though they don't have any bones? How can we move our lips even though they don't have any bones?
We can move everything if it is attached to the bones. Example: Legs & Arms.
otherwise we can't move it. Because of the Orbicularis oris muscle, it's a complex of muscles in the lips that encircles the mouth, It forms the greater part of the substance of the lips, lying between the skin and the mucus membrane, and extending from the edge of each lip to its root.
The following is multiple choice question (with options) to answer.
By what are skeletal muscles attached to bones? | [
"joints",
"veins",
"tendons",
"ligaments"
] | C | Most muscles are skeletal muscles, which are attached to bones by tendons. Skeletal muscles work in pairs to move bones back and forth at joints. |
SciQ | SciQ-3294 | geophysics, hydrology, geysers
Are the 65 minute and 91 minute values given for the eruption times simply a byproduct of needing more time for the steam to "recharge" after a larger eruption, or is there a deeper interplay between the underground cavity and the main channel that causes some sort of a vortex that has a (somewhat) regular periodicity? First I would like to say this is not my area of expertise, so this should perhaps be a comment but I am not allowed yet to comment on this site.
In a simplistic view a geyser has heated water chamber with a column of water above it. The water is heated above the normal boiling temperature but is kept liquid by the pressure of the water column above it. When the water eventually starts to vaporize this reduces the pressure on the water in the chamber resulting in more rapid vaporization of the water in the chamber resulting in the eruption.
For Old Faithful assume two chambers, one chamber is lower than the other. If the temperatures in both chambers are high enough the vaporization in the upper chamber would also reduce the pressure in the lower chamber allowing it to vaporize resulting in both chambers emptying, resulting in a longer eruption. Assuming the infill and heating rates are essentially constant then the time before the next eruption would take longer because both chambers are "empty". On the other hand if the upper chamber vaporizes and but the lower one does not, either because it is not hot enough or the pressure hasn't dropped enough or back pressure from the upper chamber keeps the lower chamber liquid, then only the upper chamber will empty resulting in less time to infill and reheat.
Again not my area.
The following is multiple choice question (with options) to answer.
What is the best-known geyser in the world that also faithfully erupts every 90 minutes? | [
"old guy",
"devil's tongue",
"angel falls",
"old faithful"
] | D | Old Faithful is the best-known geyser in the world. You can see a picture of it in Figure below . The geyser erupts faithfully every 90 minutes, day after day. During each eruption, it may release as much as 30,000 liters of water!. |
SciQ | SciQ-3295 | mechanical-engineering, structural-engineering, materials
The net kinetic energy change for object A is $(1/2)m_A (v_{f}^2 - v_{Ao}^2)$. Apply the same for object B.
As for energy absorbed by the objects individually, the answer is ambiguous. The objects cease to exist as individual objects at the moment of the collision. Any energy lost is absorbed by the final combined object, not by any one individually.
The following is multiple choice question (with options) to answer.
What kind of energy constitutes the total kinetic energy of all the atoms that make up an object? | [
"atmospheric energy",
"kinetic energy",
"thermal energy",
"phenomena energy"
] | C | The atoms that make up matter are in constant motion, so they have kinetic energy. All that motion gives matter thermal energy. Thermal energy is defined as the total kinetic energy of all the atoms that make up an object. It depends on how fast the atoms are moving and how many atoms the object has. Therefore, an object with more mass has greater thermal energy than an object with less mass, even if their individual atoms are moving at the same speed. You can see an example of this in Figure below . |
SciQ | SciQ-3296 | species-identification, zoology
Title: Are these birds in video real? What are they called? I recently came acroos this video : https://m.facebook.com/story.php?story_fbid=1053324651468913&id=492140647587319
I want to know whether these birds are real or edited? If they're real, what are their names? Yes, they are real, that's not a CGI. That footage belongs to The Cornell Lab of Ornithology, and those are birds-of-paradise.
The first one is a Wilson's Bird of Paradise (Diphyllodes respublica). Here is an image of it:
The second one, showing a courtship display, is a Superb Bird of Paradise (Lophorina superba). Here is an image of it:
And the courtship display:
The third one is a King Bird of Paradise (Cicinnurus regius). Here is an image of it:
The next one is the Wahnes's parotia (Parotia wahnesi). Here is a picture of it:
The last one is a King of Saxony Bird of Paradise (Pteridophora alberti). Here is its picture:
Finally, here is the only correct way (just kidding) to watch any video with birds of paradise: narrated by David Attenborough! Have a look:
https://www.youtube.com/watch?v=nWfyw51DQfU
The following is multiple choice question (with options) to answer.
What is the name for birds that live on water like ducks? | [
"landfowl",
"guineafowl",
"waterfowl",
"gamefowl"
] | C | Waterfowl are birds that live on the water. These include ducks, geese, swans, and pelicans, to name a few. Landfowl are ground-feeding birds such as chickens and turkeys. Penguins are a group of flightless birds adapted for life in the water with flippers. Diurnal raptors are birds of prey that hunt during the day. These include falcons, eagles and hawks. Nocturnal raptors hunt during the night. These include various types of owls. Parrots are brightly colored and very intelligent. They are found in the tropics and include cockatoos, parrots, and parakeets. |
SciQ | SciQ-3297 | botany, reproduction
Title: Are the seeds in a single capsicum fruit genetically identical? Hopefully not a too-basic question for the venue. I'm a chile pepper growing hobbyist and have spent some time searching around and reading up on pepper (angiosperm) reproduction, but I'm not getting a clear picture of the details.
It seems like flowers have multiple ovules and it seems like one pollen-grain landing on the stigma leads to fertilization of a single ovule. And it seems like that process produces a single seed.
But that fertilization also prompts fruit growth and flower death and capsicum fruits have many seeds, never just one (that I've ever seen).
So, does each seed have a potentially different father? Or are the multiple seeds generated through a reproductive/cloning process that I'm not seeing written about? Or something else? No, the seeds are not genetically identical. Each seed come from the fertilization of an ovum with a sperm from a separate pollen grain. Since each pollen grain can come from a different plant, the seeds will generally differ from one another.
Additionally, even ova from a single plant will not usually be genetically identical to one another. This is because the process that creates the ova (meiosis) shuffles the genes of the parent plant on then places only half into the ovum. The same kind of shuffling goes on in the creation of pollen grains.
In the chili pepper genus (Capsicum), plants are predominantly self-pollinating. This means the majority of the pollen for the seeds in a fruit will come from the very same plant. This generally reduces the amount of variation seen in the offspring compared to complete cross-plant pollination. Some cross-pollination can nevertheless occur if there are other varieties in the neighborhood. The fruit will not show the effects of the new genetic combinations present in its seed, but only a plant grown from the seed will make the differences evident.
The following is multiple choice question (with options) to answer.
Spores are generally produced through what type of reproduction? | [
"hormone",
"similar",
"sexual",
"asexual"
] | C | The lifecycle of basidiomycetes includes alternation of generations (Figure 24.16). Spores are generally produced through sexual reproduction, rather than asexual reproduction. The club-shaped basidium carries spores called basidiospores. In the basidium, nuclei of two different mating strains fuse (karyogamy), giving rise to a diploid zygote that then undergoes meiosis. The haploid nuclei migrate into basidiospores, which germinate and generate monokaryotic hyphae. The mycelium that results is called a primary mycelium. Mycelia of different mating strains can combine and produce a secondary mycelium that contains haploid nuclei of two different mating strains. This is the dikaryotic stage of the basidiomyces lifecyle and and it is the dominant stage. Eventually, the secondary mycelium generates a basidiocarp, which is a fruiting body that protrudes from the ground—this is what we think of as a mushroom. The basidiocarp bears the developing basidia on the gills under its cap. |
SciQ | SciQ-3298 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
What do we call the diffusion of water across a membrane because of a difference in concentration? | [
"electrolysis",
"hemostasis",
"osmosis",
"cell transportation"
] | C | The diffusion of water across a membrane because of a difference in concentration is called osmosis. |
SciQ | SciQ-3299 | $4.7\times {10}^{-13}$
### A General Note: Scientific Notation
A number is written in scientific notation if it is written in the form $a\times {10}^{n}$, where $1\le |a|<10$ and $n$ is an integer.
### Example 10: Converting Standard Notation to Scientific Notation
Write each number in scientific notation.
1. Distance to Andromeda Galaxy from Earth: 24,000,000,000,000,000,000,000 m
2. Diameter of Andromeda Galaxy: 1,300,000,000,000,000,000,000 m
3. Number of stars in Andromeda Galaxy: 1,000,000,000,000
4. Diameter of electron: 0.00000000000094 m
5. Probability of being struck by lightning in any single year: 0.00000143
### Solution
The following is multiple choice question (with options) to answer.
Scientific notation expresses a number as a what, times a power of 10? | [
"fraction",
"function",
"coefficient",
"expression"
] | C | Scientific notation expresses a number as a coefficient times a power of 10. |
SciQ | SciQ-3300 | inorganic-chemistry, physical-chemistry, quantum-chemistry, electronic-configuration, terminology
In the sodium atom pairs of $^2\!P_{1/2}$, $^2\!P_{3/2}$ states result from the promotion of the 3s valence electron to any $np$ orbital with $n > 2$. It is convenient to label the states with this value of $n$, as $n{}^2\!P_{1/2}$ and $n{}^2\!P_{3/2}$, the n label being helpful for states that arise when only one electron is promoted and the unpromoted electrons are either in filled orbitals or in an $s$ orbital. The $n$ label can be used, therefore, for hydrogen, the alkali metals, helium and the alkaline earths. In other atoms it is usual to precede the state symbols by the configuration of the electrons in unfilled orbitals, as in the $2p3p~{}^1\!S_0$ state of carbon.
The following is multiple choice question (with options) to answer.
How many valence electrons does a sodium atom have ? | [
"two",
"six",
"three",
"one"
] | D | A: Any element in group 1 has just one valence electron. Examples include hydrogen (H), lithium (Li), and sodium (Na). Any element in group 18 has eight valence electrons (except for helium, which has a total of just two electrons). Examples include neon (Ne), argon (Ar), and krypton (Kr). Oxygen, like all the other elements in group 16, has six valence electrons. |
SciQ | SciQ-3301 | cell-biology, cancer, cloning
Title: Difference between clonal and subclonal mutations I'm a physicist writing a proposal that has to do with cancer as a disease driven by evolutionary selection. As far as I understand, all tumors start with a single precursor (single cell or group of cells), and the other cells derive from this precursor by cycles of alterations and selection processes.
Reading recent articles, such as this, I learned that the derived cells include both clones and subclones. Since I'm not sure I understood things correctly, I have a few questions on the difference between the two words:
Is it OK to call clones the cells derived from the precursors?
When should I use subclones?
In the case of heterogeneity, is it fine to call clonal population a group of clones with the same characteristics? clones means when a cell has the same DNA characteristics as his predecessor so in that case of yours you could say that those cells are clones while for sub-clones I am not that sure, the difference of clone and sub-clone is that a sub-clone is basically a clone who is then remade with a different characteristic(an upgrade if you will) , since cancer are mutated cells you could call them like that but only if you study its DNA, meaning you have to study deep to find out if there are sub-clones in there. AS for the 3 question I didn't quite understood what you meant cuz you just used 2 words with opposite meaning because heterogeneity means a group of organismes with different characteristics and clonal population means organismes with same DNA ( much like a colony of bacteria).
The following is multiple choice question (with options) to answer.
Within an organism, the cells that give rise to the next generation are known as germ cells, while those that do not (that is, the cells that die when the organism dies) are known as what cells? | [
"somatic",
"neural",
"cloning",
"xylem"
] | A | reality versus abstraction. It is organisms, whether single- or multi-cellular, that produce new organisms. As we will discuss in detail when we consider the origins of multicellular organisms, a cell within a multicellular organism normally cannot survive outside the organism nor can it produce a new organism - it depends upon cooperation with the other cells of the organism. In fact, each multicellular organism is an example of a cooperative, highly integrated social system. The cells of a typical multicellular organism are part of a social system in which most cells have given up their ability to reproduce a new organism; their future depends upon the reproductive success of the organism of which they are a part. It is the organism’s success in generating new organisms that underlies evolution’s selective mechanisms. Within the organism, the cells that give rise to the next generation of organism are known as germ cells, those that do not (that is, the cells that die when the organism dies) are known as somatic cells.47 All organisms in the modern world, and for apparently the last ~3.5-3.8 billion years, arise from a pre-existing organism or, in the case of sexually reproducing organisms, from the cooperation of two organisms, an example of social evolution that we will consider in greater detail in Chapter 4. We will also see that breakdowns in such social systems can lead to the death of the organism or the disruption of the social system. Cancer is the most obvious example of an anti-social behavior; in evolutionary terms, it can, initially, be rewarded (more copies of the cancerous cell are produced) but ultimately leads to the extinction of the cancer, and often the death of the organism within which the cancer occurs.48 This is because evolutionary mechanisms are not driven by long term outcomes, but only by immediate ones. Spontaneous generation and the origin of life
The ubiquity of organisms raises obvious questions: how did life start and what led to all these different types of organisms? At one point, people believed that these two questions had a single answer, but we now recognize that they are really two quite distinct questions and their answers involve distinct mechanisms. An early view held by those who thought about such things was that supernatural processes were necessary to produced life in general and human beings in particular. The articulation of the Cell Theory and the Theory of Evolution by Natural Selection, which we will discuss in detail in the next chapter, together with an accumulation of data enables us to conclude quite persuasively that life had a single successful origin, that only natural processes were involved, and that various (again natural) evolutionary processes generated the diversity of life. But how did life itself originate? It used to be widely accepted that various types of organisms, such as flies, frogs, and even mice, could arise spontaneously, from non-living matter.49 Flies, for example, were thought to appear from rotting flesh and mice from wheat. If true, on-going spontaneous generation would have profound implications for our understanding of biological systems. For example,. |
SciQ | SciQ-3302 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
An external opening in the what of amphibians allows wastes and gametes to exit the body? | [
"cloaca",
"urethra",
"oral cavity",
"anus"
] | A | All amphibians have digestive, excretory, and reproductive systems. All three of these organ systems use a single body cavity, called the cloaca. Wastes enter the cloaca from the digestive and excretory systems. Gametes enter the cloaca from the reproductive system. A single external opening in the cloaca allows the wastes and gametes to exit the body. (Many other four legged vertebrates also have a cloaca. ). |
SciQ | SciQ-3303 | climate-change, climatology
Thus, your question is a little misconstrued: we can't answer "Who are the 3%?" because the 3% are research articles rather than people. However, we can ask "Which are the 3% of published research abstracts which do not support the scientific consensus?" And since Cook et al. (2013) is an open access paper with supporting data provided, you can easily answer this question for yourself: simply download the data file from the supplementary data page and look at the papers with an endorsement rating of 5, 6, or 7. (It's in CSV format, so is easy to load into a spreadsheet or text editor.) Further supplementary data is available from the project page at Skeptical Science, and replication of the research is actively encouraged. If you're interested in the actual people behind the 3% of "non-consensus" papers you can look at the author lists for those publications (though of course there's no guarantee that all those authors would still stand by all their conclusions).
I suggest that you start your investigations by reading the paper itself. It's clear and concise, and will give you much more thorough information about the methodology and supporting data than I've been able to fit into this answer.
The following is multiple choice question (with options) to answer.
What kind of scientists measure percentages of sand, silt, and clay? | [
"soil scientists",
"texture scientists",
"amount scientists",
"petro scientists"
] | A | Soil scientists measure the percentage of sand, silt, and clay in soil. They plot this information on a triangular diagram, with each type of particle at one corner ( Figure below ). |
SciQ | SciQ-3304 | biochemistry, endocrinology, cell-signaling
Title: Effect of steroid hormone on specific cells? As steroid hormones can pass through the plasma membrane by simple diffusion because they are lipid derived hormones, it means that they are capable of passing through every cell of our body, BUT why are only specific cells responsive against steroid hormones?
For example, all of our body cells almost contains the genes for the development of secondary sexual characters but why do only specific cells show a response against these steroid hormones because the development of secondary sexual characters occur only in specific region of our body, that is, beard formation occur only in a specific region of the face, etc.
IN SUMMARY: When steroid hormones can pass through every cell of our body then why do they show only a localized response? Unlike other types of hormones, steroid hormones do not have to bind to plasma membrane receptors. Instead, they can interact with intracellular receptors that are themselves transcription activators. Steroid hormones too hydrophobic to dissolve readily in the blood travel on specific carrier proteins from their point of release to their target tissues. In the target tissue, the hormone passes through the plasma membrane by simple diffusion and binds to its specific receptor protein in the cytoplasm. The receptor-hormone complex then translocates into the nucleus where it acts by binding to highly specific DNA sequences called hormone response elements (HREs), thereby altering gene expression.
Hormone binding triggers changes in the conformation of the receptor proteins so that they be- come capable of interacting with additional transcription factors. The bound hormone-receptor complex can either enhance or suppress the expression of adjacent genes.
The DNA sequences (HREs) to which hormone- receptor complexes bind are similar in length and arrangement, but differ in sequence, for the various steroid hormones. Each receptor has a consensus HRE sequence to which the hormone-receptor complex binds well, with each consensus consisting of two six-nucleotide sequences, either contiguous or separated by three nucleotides,
The ability of a given hormone to act through the hormone-receptor complex to alter the expression of a specific gene depends on the exact sequence of the HRE, its position relative to the gene, and the number of HREs associated with the gene.
The following is multiple choice question (with options) to answer.
What hormone affects developent and maturation in animals? | [
"melatonin",
"insulin",
"dopamine",
"thyroid"
] | D | |
SciQ | SciQ-3305 | paleontology
Title: How to start studying dinosaurs and pre-historic mammals/sea creatures I'm kind new to this hole thing of dinosaurs that I'm really interested in, are there any good books/websites/webpages to study the biology of pre-historic creatures? Dinosaurs, mammals, fishes, anything that is not alive anymore. Also, any good books about the history of how these species evolved and the history behind them would be appreciated. Here's what it takes to really study this: you need to go through the whole bachelor program for geoscientists, that includes fundamental geodynamics like plate tectonics, magmatism, volcanism, volcanic and metamorphic rocks and generally the cycles that make up earth's internal dynamics.
Then there is the huge field of external factors, like sediment geology (that's really complicated stuff), weathering and transport and how soils come to being, diagenesis and the structures sediments can form and their classifications. Role of the ocean (that's where it starts, before all) and the atmosphere, of course.
When through that, usually 4 semesters or so, you can start to specialize. For paleontolgy you need knowledge of earth history, of course, it's subdivision, and the conditions at certain times as far as they are known. Once that's done, then comes real paleontology: Animals (invertebrates and vertebrates), plants, and their development, biological evolution (that's frequently underrated, I find), taphonomy, ... For a sturdy base count another 2-4 semesters.
You may see that even a bunch of websites, maybe all of them together, cannot replace actual study. I am not aware of any site that even gives a reasonable overview of the field. Geoscience, and thus paleontology, touch many fields of natural science.
That said, when asked "How to learn about animal paleontology ?" I allways mention Micheal Benton, Vertebrate Paleontology. It needs a basic understanding of geoscience, evolution and skeleton anatomy. Functional morphology, phylogeny and an overview over sediment geology and earth history also won't harm, but you could give it a try. Some things are explained in between.
The following is multiple choice question (with options) to answer.
The three types of mammals are characterized by their method of what? | [
"differentiation",
"specializaiton",
"pattern",
"reproduction"
] | D | There are three types of mammals, characterized by their method of reproduction. All mammals, except for a few, are viviparous , meaning they produce live young instead of laying eggs. The monotremes , however, have birdlike and reptilian characteristics, such as laying eggs and a cloaca. An example of a monotreme is the platypus with its birdlike beak and egg-laying characteristics. The echidnas are the only other monotreme mammals. A second type of mammal, the marsupial mammal, includes kangaroos, wallabies, koalas and possums. These mammals give birth to underdeveloped embryos, which then climb from the birth canal into a pouch on the front of the mother's body, where it feeds and continues to grow. The remainder of mammals, which is the majority of mammals, are placental mammals. These mammals develop in the mother's uterus, receiving nutrients across the placenta. Placental mammals include humans, rabbits, squirrels, whales, elephants, shrews, and armadillos. Dogs and cats, and sheep, cattle and horses are also placental mammals. |
SciQ | SciQ-3306 | exoplanet
It's probably possible to have volcanic eruptions even though dozens or maybe even hundreds of miles of exotic ice because the heat has to go somewhere, eventually, assing it's likely to build up over time, so either by circulation of eruption, the heat has push through at some point. This even happens on so called "dead" planets like Mars or even the Moon. Mars still has the occasional volcanic eruption, just not very often.
But water worlds certainly can have plate tectonics. There's nothing in the water that would prevent it from happening. Plate Tectonics is, as I understand it, primarily a factor of the size of the planet. Gas planets - different story, but planets with a hard surface, Earth sized, a tiny bit smaller to a fair bit but not much bigger are good candidates for plate tectonics (I think). There's some debate on how large, I think, still going on. But I remember reading that ocean/water worlds might even be more likely to have plate tectonics. Plate tectonics is definitely something we'd look for if we ever get a close enough look at other planets in different solar-systems (exoplanets).
Just my thoughts on this. Not meant to be complete or definitive.
The following is multiple choice question (with options) to answer.
What planet has the most volcanoes? | [
"venus",
"uranus",
"Mars",
"Earth"
] | A | Venus has more volcanoes than any other planet. There are between 100,000 and one million volcanoes on Venus! Most of the volcanoes are now inactive. There are also a large number of craters. This means that Venus doesn’t have tectonic plates. Plate tectonics on Earth erases features over time. Figure below is an image made using radar data. The volcano is Maat Mons. Lava beds are in the foreground. Scientists think the color of sunlight on Venus is reddish-brown. |
SciQ | SciQ-3307 | dna
Title: is having more copies of gene better then having it less? if it's why is it ? I was learning about elephants rarely getting cancer and learn that elephants have 40 copies of genes while human only has 2 copies of genes each from parents.
so I wonder if it's better to have more copies of the gene then having 2
I was learning about elephants rarely getting cancer and learn that elephants have 40 copies of genes while human only has 2 copies of genes each from parents.
Where did you read that? Please always include your sources.
What you're saying is unclear but I suppose you are referring to ploidy variation among species and not to CNV (Copy Number Variation) for specific genes. It is also possible that you mistake alleles for genes but it is impossible to tell where your misunderstanding is without reading from your source. I will assume you talked about ploidy variation.
Elephants are diploids, just like humans. So, the claim appears flat wrong.
so I wonder if it's better to have more copies of the gene then having 2
There is no general rule. Because having a single working copy is often enough, high ploidy can be a pretty good defense against loss of function mutations but that's only valid for some time just after a recent polyplodization event as the relaxation of selection pressures against such mutations will lead these deleterious mutations to higher frequencies (at mutation - drift - selection equilibrium).
Note that doubling or halving the number of gene copies often yield to issues in dosage of mRNA and protein expressed. Related to that you might to read about dosage compensation
The following is multiple choice question (with options) to answer.
Gene duplications that are able to persist over many generations without causing too much harm to an organism or species can lead to what? | [
"characteristics",
"mutations",
"permutations",
"parasites"
] | B | |
SciQ | SciQ-3308 | orbital-motion, sun, earth, relative-motion
Title: Revolution of Earth If all motion is relative, how do we know that the Earth revolves around the sun?
Or we are just making the above statement from the frame of reference in which Sun is at the origin? Motion may be relative, but only in certain reference frames will Newton's Second Law,
$$ \vec{F} = m \vec{a}, $$
hold without having to invoke ad hoc forces $\vec{F}$.
In this case, suppose we did look at everything in the reference frame where the Earth is not moving. Then the Sun would be moving in a giant circle, $1\ \mathrm{AU}$ in radius, every year. But since even before Newton we've known that objects should just move at the same speed and in the same direction unless acted upon by an external force. Uniform circular motion requires something to be accelerating you ($\vec{a}$) all the time.
What, then, is acting on the Sun to accelerate it? Since $m$ is so large for the Sun, you need quite a large $\vec{F}$ to make the necessary $\vec{a}$. The Earth's gravity won't suffice. In fact, the "force" here is known as centrifugal force, and it is "fictitious" in the sense that a better choice of reference frame would eliminate it.
So yes, you can say that the Sun moves around the Earth, but only subject to the caveat that you are not talking about an inertial frame. Instead, that statement only holds in a reference frame where objects experience some centrifugal "force," which does not come from any fundamental interaction like gravity or electromagnetism.
The following is multiple choice question (with options) to answer.
What keeps earth in orbit around the sun? | [
"motion",
"gravity",
"momentum",
"energy"
] | B | Why do satellites stay in orbit? Why don't they crash into Earth due to the planet's gravity? Newton’s law of universal gravitation describes what happens. Every object in the universe is attracted to every other object. Gravity makes an apple fall to the ground. Gravity also keeps you from floating away into the sky. Gravity holds the Moon in orbit around Earth. It keeps Earth in orbit around the Sun. |
SciQ | SciQ-3309 | newtonian-mechanics, energy, work, integration, calculus
Title: Work-Energy Theorem for a path that is not smooth In the analysis of Newtonian Mechanics for a single particle, we come across the definition of work and also the Work-Kinetic Energy theorem:
For a single particle, the work done on a particle by a force $\textbf{F}$ in transforming the particle from condition A to condition B is defined as: $$W_{AB} = \int_A^B{\textbf{F}}.d\textbf{r}$$
and the integrand can be reduced to an exact differential, if $\bf{F}$ is the net force acting on the particle, as:
$${\textbf{F}}.d\textbf{r} = m.\frac{d\textbf{v}}{dt}\textbf{.}\frac{d\textbf{r}}{dt}.dt = m\textbf{v}.d\textbf{v} = dK \implies \boxed{W_{AB} = K_B - K_A}$$
However, can the same theorem hold if the curve $\textbf{r} = \textbf{r}(t)$ is such that there are points where $\textbf{r}(t)$ is not differentiable, such as path 1 in the picture below?
The following is multiple choice question (with options) to answer.
The work-energy theorem states that the net work on a system equals the change in what type of energy? | [
"kinetic energy",
"residual energy",
"binary energy",
"new energy"
] | A | How the Work-Energy Theorem Applies Now let us consider what form the work-energy theorem takes when both conservative and nonconservative forces act. We will see that the work done by nonconservative forces equals the change in the mechanical energy of a system. As noted in Kinetic Energy and the Work-Energy Theorem, the work-energy theorem states that the net work on a system equals the change in its kinetic energy, or W net = ΔKE . The net work is the sum of the work by nonconservative forces plus the work by conservative forces. That is,. |
SciQ | SciQ-3310 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
Living organisms release carbon dioxide into the atmosphere by what method? | [
"genomic respiration",
"widespread respiration",
"major respiration",
"cellular respiration"
] | D | Cellular respiration by living things releases carbon into the atmosphere or ocean as carbon dioxide. |
SciQ | SciQ-3311 | evolution, mammals
Title: Why haven't land animals evolved beyond urination? It occurred to me (while urinating) that this would seem to be selected against because water is a scarce resource. Why are we constantly losing water we don't need to through urination? What is it about the chemistry of urine and the waste products eliminated that make urination necessary as opposed to eliminating them through defecation and recovering the water on the way out? It is probably true that toilets and other resting-ish area are always a great place to think about biology, I agree $\ddot \smile$.
Why do we urinate?
In short, urine contains the waste from our blood while defecation is just the stuff that we haven't digested. Kidneys are the organs responsible for draining wastes (mostly nitrogen-containing, or nitrogenous, wastes) from our blood.
Trade-off: energy cost vs. water loss
You're correct that the loss of water through urination is a considerable cost for an organism (especially those living in dry environments). But the amount of water used to excrete nitrogenous wastes is negatively correlated with the energy it costs to perform this excretion. In other words, there is a trade-off between water and energy loss during nitrogen excretion. Also, the question of toxicity is important.
Three ways to excrete nitrogenous wastes
Animals basically have three choices to excrete nitrogenous wastes:
Uric acid (excreted by uricotelic organisms)
Solid (crystal) with low water solubility
Low toxicity
Little water is needed
Lots of energy is needed
Ammonia (excreted by aminotelic organisms)
Highly soluble in water
High toxicity
Lots of water is needed to dilute it because of the toxicity
Not much energy is needed
Urea (excreted by ureotelic organisms)
Solid but highly soluble in water
"medium" amount of water is needed
"medium" toxicity
"medium" amount of energy is needed
The following is multiple choice question (with options) to answer.
Excretory organs that conserve what essential substance help terrestrial animals to avoid desiccation? | [
"food",
"air",
"metabolytes",
"water"
] | D | |
SciQ | SciQ-3312 | sun, solar-system, solar-system-exploration
Title: How is SUN rotating? Is Sun rotating anti clockwise similar to planet Venus or is it continuously changing it rotation ? The sun rotates in anti-clockwise direction (when viewed from the north).
The Sun, however, does not rotate as a whole body. It is made up of gaseous plasma and the time taken to complete one rotation increases with latitude. It takes around 25 days at equator and 38 days at poles (it is judged by the location of sun spots).
The following is multiple choice question (with options) to answer.
Venus rotates slowly in a direction opposite to the direction of what? | [
"the Earth's orbit",
"the orbit of Mars",
"its orbit",
"the sun"
] | C | Venus rotates slowly in a direction opposite to the direction of its orbit. |
SciQ | SciQ-3313 | organic-chemistry, acid-base, ph
The usual rule that "$\mathrm{pH}$ of 7 is neutral" comes from solutions in water: Water has the property that it can be converted into, and self-converts between ("auto-ioniziation") separate $\mathrm{H}^{+}$ and $\mathrm{OH}^{-}$ ions and its usual molecular form, $\mathrm{H}_2\mathrm{O}$. When one is dealing with pure water with no adulterants present, there is always, due to this process, around $10^{-7}\ \mathrm{\frac{mol}{dm^3}}$ of $\mathrm{H}^{+}$ present (though actually, this depends on temperature, but around room temp, it is around this much). Decimal logarithm of $10^{-7}$ is -7, hence the $\mathrm{pH}$ is 7. When you throw some acid in and it releases its protonic payload, the concentration of $\mathrm{H}^{+}$ rises by that amount, thus the $\mathrm{pH}$ drops.
The following is multiple choice question (with options) to answer.
What is the ph of pure water? | [
"2",
"4",
"5",
"7"
] | D | milk of magnesia, pH = 10.5 2. pure water, pH = 7 3. wine, pH = 3.0. |
SciQ | SciQ-3314 | mixtures, gas-phase-chemistry
Now as it happens, for ideal gases, which the atmosphere is close to being, you can mentally subdivide the volume into tiny little equal-sized cubes, one for each atom or molecule in the mixture, and on average there would be one atom/molecule of $X$ in each fourth cube if $X$ is 25% by volume of the mixture. (I emphasize "on average" because of course since the gas atoms or molecules are continuously moving around randomly, they will bunch up and spread out momentarily all the time, so at any given instant there may be zero or many more than one $X$ atom/molecule per tiny cube.) Real mixtures in the liquid state often have at least some nonideality, e.g. even in a dilute solution of $\ce{NaCl}$ in water, you will find "structure" in the solution, with the $\ce{Na+}$ cations and $\ce{Cl-}$ anions surrounded by a fairly fixed arrangement of $\ce{H2O}$ molecules, almost like a tiny piece of clathrate, so a mental arrangement of tiny boxes is an even less accurate atomic-scale description of the solution.
In short, the percent by volume description of a mixture is only a way to characterize the amount of material that goes into it, it is not intended as any kind of implication of what the mixture looks like at the atomic scale.
As for why NASA reports the composition of the atmosphere by percent by volume: probably because it's closest to the actual experiments done to measure it. You would typically measure the composition of a gas mixture by physically separating it (e.g. by lowering the temperature until each gas liquefied) and then measuring the volume of each component. You certainly could from those measurements easily calculate a percent by moles, but – why? You introduce a calculational step between the measurement and what you report, and scientists tend to prefer getting original data, right what comes from the instrument, if possible, as a way of avoiding even the smallest risk of some error introduced in calculation.
The following is multiple choice question (with options) to answer.
The volume of a gas is comprised of about 10% matter. what is the rest? | [
"empty space",
"instead space",
"open space",
"normal space"
] | A | The volume of a gas contains only about 10% matter, with the rest being empty space. ΔHsub is equal to ΔHvap. |
SciQ | SciQ-3315 | enzymes
Accepted Name: pyruvate kinase
(because that’s what everyone uses and is in all the text books)
Other names: phosphoenolpyruvate kinase; phosphoenol transphosphorylase
pyruvate kinase (phosphorylating); fluorokinase; fluorokinase (phosphorylating); pyruvic kinase; pyruvate phosphotransferase
(note these include naming it for the reverse reaction)
Systematic name ATP:pyruvate 2-O-phosphotransferase
So why is that the systematic name? If you click back from this page to the group EC 2.7.1 to which this belongs, you will find that this group is of ‘Phosphotransferases with an Alcohol Group as Acceptor’, itself a subgroup of phosphotransferases.
So, to summarize, there is a systematic name that have been arrived at after long and careful deliberation and appears in the introductory paragraphs of scientific publications. Thereafter the common name is used, which although sometimes now recognized as a misnomer, seemed most appropriate at the time.
The following is multiple choice question (with options) to answer.
Heterotrophs is another name for what group? | [
"consumers",
"omnivores",
"producers",
"autotrophs"
] | A | Consumers are also called heterotrophs. There are several different types of heterotrophs depending on exactly what they consume. They may be herbivores, carnivores, or omnivores. |
SciQ | SciQ-3316 | genetics, cell-biology, gene-expression, cell-cycle
Title: Why don't cells double gene expression after S-Phase? In the cell cycle (G1-S-G2-M), all of the DNA is replicated during the S or Synthesis stage. The cell may then spend some considerable time in the G2 phase before splitting in the M phase. Since there is double the amount of genetic material in the G2 phase, what mechanism if any, prevents the amount of gene expression from also doubling? When the double strand is duplicated, the old strand (or, in other terms, the template) is methylated : this modification is enough to prevent the bind by the RNApol system and, by so, the transcription.
By methylation, DNA-repair systems are able to detect which is the newer strand, to discover and fix replication errors.
Here you can find additional infos
The following is multiple choice question (with options) to answer.
What is dna transcribed into after being replicated? | [
"rna",
"protein",
"gene",
"diploid chromosomes"
] | A | The three general transfers are believed to occur normally in most cells. These describe the normal flow of biological information. DNA is replicated, DNA is transcribed into RNA, and RNA is translated into protein. The three special transfers are known to occur under special conditions, such as with some viruses. The three unknown transfers are not believed to occur. |
SciQ | SciQ-3317 | evolution, terminology, phylogenetics
Title: Is there a name for this phenomenon described in "Phylogenies and the Comparative Method"? The figures below are from Felsenstein's paper "Phylogenies and the Comparative Method". I was wondering if there was a specific name for this effect where there is an apparant correlation that is actually the result of the data being structured into two separate groups, where there is no correlation within groups but an apparent correlation between groups. "Phylogenetic non-independence" doesn't seem specific enough. I've seen this termed "phylogenetic pseudoreplication", but I can't remember offhand where. I'll see if I can find it. Without a tree, the boxes and Xs essentially represent 2 data points. As Remi.b suggests, this is really just high phylogenetic signal.
The following is multiple choice question (with options) to answer.
What is name of the phenomenon where similar traits evolve independently in species that do not share a common ancestry? | [
"equation evolution",
"convergent evolution",
"coalescence evolution",
"divergent evolution"
] | B | Figure 22.31 The force on a current-carrying wire in a magnetic field is. |
SciQ | SciQ-3318 | fluid-dynamics, acceleration, harmonic-oscillator, harmonics
Title: Fluid filled harmonic oscillator A vessel (preferably circular) filled with water is accelerating unidirectionally such that the level of water is higher on one end than the other. What I want to know is that if the vessel is immediately stopped, the water level will force itself back to the equilibrium point, but in doing so push the other end up. If water is an ideal fluid, what type of oscillation will occur in this situation.
I can tell that maybe the mathematical expression for this oscillation will be complex, but please do let me know if I am thinking this correctly.
I am considering, finding the oscillation equation for infinitesimally small u-tubes(considering a 2-d plane) and integrating it to get the final expression.
Thanks in advance Consider the following diagram:
The following is multiple choice question (with options) to answer.
The flow of water through the sponge is unidirectional, driven by the beating of what? | [
"cilia",
"antennae",
"fin",
"flagella"
] | D | Sponges are characterized by a feeding system unique among animals. As sponges don't have mouths, they must feed by some other method. Sponges have tiny pores in their outer walls through which water is drawn. Cells in the sponge walls filter food from the water as the water is pumped through the body and out other larger openings. The flow of water through the sponge is unidirectional, driven by the beating of flagella, which line the surface of chambers connected by a series of canals. |
SciQ | SciQ-3319 | soft-question, advice-request
Title: How do you go from insights to formal solutions? My question pertains to the problem of translating ideas and insights to the solution (of some problem) into formal notations, thus expressing the answer formally.
In other words, having a bunch of ideas (pertaining to the solution) and transforming them into a well composed, formal solution is a process which I often find difficult.
It might be because (at times) I am not aware of enough literature in the problem domain and so have the problem of not knowing how to express my ideas. However, I would like to know if this is something that can be improved upon and if so, how? Transforming intuition into formal argument is difficult, and the degree to which it is viewed as necessary is sociological, and varies by community. In general, arguments tend to be less formal in AI conferences, reasonably formal in the "Theory A" community, and extremely formal (i.e. machine verifiable) in parts of the programming languages "Theory B" community.
Probably the best way to develop this skill is to take rigorous courses that require formal argument on problem sets. You can also just read papers in the community that you would like to publish in, but you have to make sure to actually read the arguments carefully for this to be helpful. i.e. it is easy to read a paper and feel that you understand it, but be unable to reproduce key parts of the argument. A good way to do this is to plan to actually present the paper to a group of friends. If you actually have to present the arguments on a board and answer questions, you will be able to force yourself to really understand.
Do this a few times and you should be able to construct formal arguments of your own.
The following is multiple choice question (with options) to answer.
What is the process for developing knowledge called? | [
"theory",
"evolution",
"creationism",
"science"
] | D | Science is a process for developing knowledge. Change in knowledge about the natural world is expected because there is often room for new observations which may challenge current views. No matter how well one theory explains a set of observations, it is possible that a different theory may explain them just as well or better, or may also encompass a wider range of observations. Scientists are always testing and attempting to improve theories. Scientists know that even if there is no way to gain complete knowledge about something, an increasingly accurate understanding of nature will develop over time. |
SciQ | SciQ-3320 | cardiology, fat-metabolism
Title: Can fats clog veins or capillaries? I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
I googled a bit but everything was regarding arteries.
Is it because veins have a much wider diameter than arteries that even if some fats deposit they won't clog it?
And for capillaries, they are much smaller so shouldn't they be more vulnerable to this?
In addition, I guess since one of the lymphatic vessels functions are to transport fats from capillaries in villi to bloodstream, how are they adapted to prevent deposit of fats as they carry out the transportation?
N:B I'm just an OL biology student, and also horrible at chemistry
I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
Wikipedia says this:
Veins do not develop atheromata, because they are not subjected to the same haemodynamic pressure that arteries are,[8] unless surgically moved to function as an artery, as in bypass surgery.
The cited study isn't freely available, but seems to have tested in rabbits by surgically modifying their blood flow and giving them a high fat diet.
As for capillaries, they are continuously remodeled, so while they do become clogged for a variety of reasons, once flow stops they're disassembled and new capillaries formed if the tissue becomes hypoxic.
The following is multiple choice question (with options) to answer.
Arteries, veins, and capillaries are the three main types of what? | [
"cell structures",
"blood pathways",
"blood vessels",
"blood shapes"
] | C | |
SciQ | SciQ-3321 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
Amphibians may attract mates with what? | [
"only calls",
"neither",
"only scents",
"calls or scents"
] | D | Amphibians may attract mates with calls or scents. |
SciQ | SciQ-3322 | 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 type of bounded nucleus do protists have? | [
"Ribosomes",
"Endoplasmic reticulum",
"membrane",
"Mitochondrion"
] | C | |
SciQ | SciQ-3323 | evolution, anatomy, organs
Title: Why Is Most Life Symmetrical Externally But Not Internally? Mammals, reptiles, arachnids, insects, etc are all as far as I am aware symmetrical in appearance.
Take a human for instance, make a line from the top of our head right down the middle. However, internally it is not the same. Our organs excluding the kidneys, lungs, reproductive organs, etc are not symmetrically placed in our body.
The following is multiple choice question (with options) to answer.
Which body part is unsuitable for animals living on land? | [
"gills",
"feet",
"lungs",
"hands"
] | A | |
SciQ | SciQ-3324 | proteins, gene-expression
Title: IPTG and lac operator with e coli for foreign gene question We did an experiment were we have e coli with a plasmid with a gene from another bacteria in it, and we put in IPTG in for induction. Will after looking up more about IPTG online I see it's related to the lac operator, which from what I've found just deals with lactose. Is there some other function that has? How can this be related to or effect the thing we put in and what we're doing? I'm missing the connection here. The lac operon contains genes which are important for the metabolization of lactose as an energy source - normally glucose is used for this purpose. Usually the operon is tighly regulated and as long as there is another source of energy it is kept in an inhibited state.
The presence of lactose removes the lac repressor from the lac operon and allows the expression of the genes and thus allowing the metabolization of lactose. The mechanism can be turned on and off depending on the presence of lactose.
IPTG is a substance which mimicks the presence of allolactose (a metabolite of lactose) and it can activate transcription from the lac operon. As IPTG (in contrast to allolactose) cannot be hydrolyzed by β-galactosidase, it's concentration in the cell stays the same. Using the lac operon and IPTG enables you to switch on the expression of the gene on your plasmid and to start the overexpression.
The following is multiple choice question (with options) to answer.
Which inducer turns on the expression of the lac genes? | [
"allolactose",
"galactose",
"glucose",
"xerophyte"
] | A | When lactose is available, a lactose metabolite called allolactose binds to the allosteric site on the repressor. This interaction causes a conformational change in the repressor shape and the repressor falls off the operator, allowing RNA polymerase to bind to the promoter and initiate transcription. Allolactose is called an inducer because it turns on, or induces the expression of the lac genes. |
SciQ | SciQ-3325 | neuroscience, brain, brain-stem
On the contrary, if the ARAS is working normally but the consciousness neural process is not, there can be alertness without, with minimal, or with some awareness. The degree of impairment of awareness depends on how much the consciousness neural process is dysfunctional. For example, in the case of damages to the consciousness neural process from diffuse cerebral hypoxia, extensive bilateral cerebral infarcts, or diffuse cerebral cortical injury, the results can be various abnormal conscious awareness’s states that range in severity of abnormal conscious awareness, depending on how much the consciousness neural process is impaired, such as (from mild to severe) acute confusional state, akinetic mutism, minimally conscious state (MCS), and vegetative state (VS). In the latter two categories, which are severe conditions, the patients can open eyes and have some reflex responses, such as blinking, chewing, and yawning, but show no (in VS) or minimal (in MCS) signs of conscious awareness of self and the environment (by clinical testing or by special investigations such as EEG, evoked potentials, and fMRI) [2].
The following is multiple choice question (with options) to answer.
What is the most common type of brain injury? | [
"Contusion",
"Anoxic Event",
"concussion",
"Diffuse Axonal"
] | C | The most common type of brain injury is a concussion. This is a bruise on the surface of the brain. It may cause temporary symptoms such as headache and confusion. Most concussions heal on their own in a few days or weeks. However, repeated concussions can lead to permanent changes in the brain. More serious brain injuries also often cause permanent brain damage. |
SciQ | SciQ-3326 | entropy, soft-question, elasticity
Title: What's the difference between elastic energy and entropic elasticity? I was reading up some articles on elasticity theory to make an essay about elastic energy in rubber bands, but in the first paragraph of this article it is said that rubber bands do not show elastic potential energy, but entropic elasticity. I've never seen this before, and since its fundamentally a thermodynamics thing, it takes the research to another field completely. What is the actual difference between entropic elasticity and ordinary elasticity? Does it matter when studying the potential energy of an elastic body? We know that all things occur to maximize entropy. (In other words, the Second Law tells us that we more often see outcomes that are more likely to occur—that is, those outcomes with higher entropy).
As outlined here, energy minimization can act as a surrogate for entropy maximization. We can interpret this as favoring both high entropy and strong bonding, as the latter releases energy that provides the entropy benefit of heating the rest of the universe.
This is all encompassed in the Gibbs free energy, which includes both internal energy and entropy terms.
For a standard metal spring, the internal energy term dominates. As typically modeled using a pair potential, the atomic/molecular spacing is shifted slightly from its (minimum) equilibrium position. (This doesn’t affect the entropy much.) The greater energy upon displacement corresponds to a restoring force that imparts springlike behavior, with linear elasticity and a constant stiffness observed for small displacements.
The ideal gas can also resist deformation (specifically, compression), but this material model has no capacity to store energy. To understand the bulk modulus of the ideal gas, we have to return to the Second Law: the drive for entropy maximization produces a restoring force toward the equilibrium configuration of pressure equilibration with the surroundings. In contrast to internal-energy-mediated elasticity, the behavior of an entropic spring is immediately nonlinear (e.g., the isothermal stiffness of the ideal gas is just its pressure), and the stiffness is strongly temperature dependent because the entropy term in the Gibbs free energy has the temperature as its coefficient.
The following is multiple choice question (with options) to answer.
Changing the shape of an elastic material gives it what type of energy? | [
"potential",
"practical",
"initial",
"thermal"
] | A | Changing the shape of an elastic material gives it potential energy. |
SciQ | SciQ-3327 | genetics
I will discuss a few concepts and slowly introduce the concept of heritability in both senses.
Phenotypic trait
The phenotype is the consequence of the genotype on the world. In brief, a phenotypic trait is any trait that an individual is made of!
Quantitative trait
A quantitative trait is any trait that you can measure and ordinate, that is any trait that you can measure with numbers. For example, height is a quantitative trait as you can say that individual A is taller than individual B which is itself taller that individual C.
Variance of a quantitative trait
In a population, different individuals can have different values for a given phenotypic trait $x$. Because we are talking about quantitative traits we can calculate the variance of the trait in the population. Let's call this variance $V_P$ such as
$$V_P=\frac{1}{N}\sum_i (x_i - \bar x)^2$$
In the above equation, $x_i$ is the value of the phenotypic trait $x$ of individual $i$. $N$ is the population size (there are $N$ individuals in the population) and $\bar x$ is the average phenotypic trait $x$ in the population.
$$\bar x = \frac{1}{N}\sum_i x_i$$
What is causing phenotypic variance
Why would a population display any phenotypic variance? Why wouldn't we just look exactly the same? What explains these differences?
For some traits, we see very little variance. To consider the example the OP gave in the post, the number of arms in the human population shows very little variance. However, there is quite a bit of variance in terms of the number of IQ, in terms of height or of weight.
There are two (main) sources of variance that are underlying this phenotypic variance. The first one is the genetic variance and the second one is the environmental variance. We will call the genetic variance $V_G$ and the environment variance $V_E$.
The following is multiple choice question (with options) to answer.
What type of traits are features that are passed from one generation to the next called? | [
"genetic traits",
"familial traits",
"inherited traits",
"generational traits"
] | C | The theory of evolution by natural selection means that the inherited traits of a population change over time. Inherited traits are features that are passed from one generation to the next. For example, your eye color is an inherited trait. You inherited your eye color from your parents. Inherited traits are different from acquired traits , or traits that organisms develop over a lifetime, such as strong muscles from working out ( Figure below ). |
SciQ | SciQ-3328 | organic-chemistry
Title: What are the minimal chemical requirements for a food which we all can eat? I've been puzzled by the following though experiment for the past few days:
I want to make my own food from scratch, but I do not know where to start from.
I want to be 100% sure that what I eat will never contains something that can damage my body. For example: If you buy something from the local market you can not be 100% sure that it's safe to eat. (99.9 % maybe... but that's not 100%)
I want to ask you to tell me, how can I make a food that I can eat, or should I say - live on it, for the rest of my life, that's 100% safe, I can control every aspect of it's creation and has many combinations of taste because I love diversity.
Thank you for your time : )
Edit:
Because I realized my question is very broad and indeed is a little... too much scientific I want to close it. But before I do so, here's what I had in mind:
I wanted to take some chemical elements, put them in a jar, run some electricity, heat, whatever through it, filter it, do some additional processing and eat it.
I wanted to know if the stomach can take it, because I was going to eat food that's not hard to digest. Considering the three basic biomolecules used by the body are carbohydrates, lipids, and proteins, you would need to consume these three molecules only. Now we can choose three substances.
Glucose, one of the most basic carbohydrates, is needed for ATP production, so that would be a food choice there.
Any oil or butter will provide lipids.
Protein comes from a variety of sources. Meat is typically though of as the best, but nuts are a pretty good source too.
Since nuts satisfy proteins and lipids, I'd say honey roasted peanuts are the most basic food you could live off of, if you replace pure glucose for the honey.
The following is multiple choice question (with options) to answer.
What is your body made up of? | [
"energy",
"trillions of cells",
"skin",
"millions of elements"
] | B | According to the cell theory , all living things are made up of cells, which is the structural unit of living organisms, and living cells always come from other living cells. In fact, each living thing begins life as a single cell. Some living things, such as bacteria, remain single-celled. Other living things, including plants and animals, grow and develop into many cells. Your own body is made up of an amazing 100 trillion cells! But even you—like all other living things—began life as a single cell. |
SciQ | SciQ-3329 | biochemistry, gas-laws
Title: What is the state of aggregation (gas, liquid) of oxygen in blood? Atmospheric oxygen is in O2 and a gas. Then we inhale the air, our efficient lungs do the magic to filter out the oxygen and push them into the blood stream.
When we say hemo and globin transport the oxygen using the iron ions. In what state oxygen is transported in the blood? as a gas or a liquid or an ion? It is hard for me to conceive of the idea that oxygen would be in gaseous form in the blood. "GAS in blood?" e.g. Arterial Blood Gas Test
Also, how does the lungs convert the gas into something that is compatible to be in blood?
References:
Amount of Oxygen in the Blood Regarding the state of oxygen in blood: It is in solution in the blood plasma (which mostly consists of water), in the form of single molecules. Think of water which you leave exposed to air: carbon dioxide will be captured and dissolved (along with the other gases in air), but these molecules are not gaseous or liquid, but rather "in solution", which is different from the "classical" states.
Back to oxygen: As your reference already states, most of the oxygen in solution will bind to hemoglobin. The actual state of oxygen in that complex has been debated, but it is believed to be reduced by the hemoglobin iron to the superoxide anion, coordinated to Fe$^{3+}$. See Wikipedia on this.
Also, the lungs do not "convert" the atmospheric oxygen to anything, they rather allow, due to their very large surface area, the quick exchange of oxygen/carbon dioxide in solution and in the air.
The following is multiple choice question (with options) to answer.
Hemoglobin is responsible for transporting what within our blood? | [
"nitrogen",
"dioxide",
"oxygen",
"water"
] | C | To predict the relative stabilities of metal complexes with different ligands. One of the most important properties of metallic elements is their ability to act as Lewis acids that form complexes with a variety of Lewis bases. A metal complex consists of a central metal atom or ion that is bonded to one or more ligands (from the Latinligare, meaning “to bind”), which are ions or molecules that contain one or more pairs of electrons that can be shared with the metal. Metal complexes can be neutral, such as Co(NH3)3Cl3; positively charged, such as [Nd(H2O)9]3+; or negatively charged, such as [UF8]4−. Electrically charged metal complexes are sometimes called complex ions. A coordination compound contains one or more metal complexes. Coordination compounds are important for at least three reasons. First, most of the elements in the periodic table are metals, and almost all metals form complexes, so metal complexes are a feature of the chemistry of more than half the elements. Second, many industrial catalysts are metal complexes, and such catalysts are steadily becoming more important as a way to control reactivity. For example, a mixture of a titanium complex and an organometallic compound of aluminum is the catalyst used to produce most of the polyethylene and polypropylene “plastic” items we use every day. Finally, transition-metal complexes are essential in biochemistry. Examples include hemoglobin, an iron complex that transports oxygen in our blood; cytochromes, iron complexes that transfer electrons in our cells; and complexes of Fe, Zn, Cu, and Mo that are crucial components of certain enzymes, the catalysts for all biological reactions. Metal complexes are so important in biology that we consider the topic separately in Section 23.6 "Transition Metals in Biology". |
SciQ | SciQ-3330 | zoology, ichthyology, marine-biology
Switek goes on to to talk about exceptions in some marine mammals:
At this point some of you might raise the point that living pinnipeds like seals and sea lions move in a side-to-side motion underwater. That may be true on a superficial level, but pinnipeds primarily use their modified limbs (hindlimbs in seals and forelimbs in sea lions) to move through the water; they aren’t relying on propulsion from a large fluke or caudal fin providing most of the propulsion with the front fins/limbs providing lift and allowing for change in direction. This diversity of strategies in living marine mammals suggests differing situations encountered by differing ancestors with their own suites of characteristics, but in the case of whales it seems that their ancestors were best fitted to move by undulating their spinal column and using their limbs to provide some extra propulsion/direction.
The following is multiple choice question (with options) to answer.
How do bipedal creatures walk? | [
"on six legs",
"on four legs",
"on two legs",
"on twelve legs"
] | C | Birds are endothermic tetrapod vertebrates. They are bipedal, which means they walk on two legs. Birds also lay amniotic eggs with hard, calcium carbonate shells. Although birds are the most recent class of vertebrates to evolve, they are now the most numerous vertebrates on Earth. Why have birds been so successful? What traits allowed them to increase and diversify so rapidly? Birds can vary considerably in size, as you can see from the world’s smallest and largest birds, pictured in Figure below . The tiny bee hummingbird is just 5 centimeters (2 inches) long, whereas the ostrich towers over people at a height of 2.7 meters (9 feet). All modern birds have wings, feathers, and beaks. They have a number of other unique traits as well, most of which are adaptations for flight. Flight is used by birds as a means of locomotion in order to find food and mates and to avoid predators. Although not all modern birds can fly, they all evolved from ancestors that could. |
SciQ | SciQ-3331 | identification, minerals
Title: How can chemists distinguish pure chemical element specimens that look almost "the same" as well as what deposit is what in a multimineral mined rock? As a non chemist I am most often charmed when visiting Wikipedia articles of chemical elements and see images of very pure specimens of element after element, proton by proton, and often also metal cube specimen made from smithing similar pure deposits.
The wiki article Periodic table allows me to do so easily; here are some elements I found looking almost the same and don't think I personally could distinguish between them without some instrument:
molybdenum and manganase
titanium and chromium
rutenium and cadmium
sodium and aluminium
silicone and germanium
The following is multiple choice question (with options) to answer.
Any sample of matter that has the same physical and chemical properties throughout the sample is called what? | [
"substance",
"type",
"molecule",
"element"
] | A | Elements and Compounds Any sample of matter that has the same physical and chemical properties throughout the sample is called a substance. There are two types of substances. A substance that cannot be broken down into chemically simpler components is an element. Aluminum, which is used in soda cans, is an element. A substance that can be broken down into chemically simpler components (because it has more than one element) is acompound (Figure 1.2 "The General Steps of the Scientific Method"). Water is a compound composed of the elements hydrogen and oxygen. Today, there are about 118 elements in the known universe. In contrast, scientists have identified tens of millions of different compounds to date. |
SciQ | SciQ-3332 | inertial-frames, relative-motion, doppler-effect
Title: Which one is moving? If there are two objects moving relative to each other at a constant velocity, is there any experiment the bodies themselves can do to determine which one is moving?
EDIT: The comments say "NO". So please can anyone explain this:
If we could make bodies produce sound and while one produces other calculates the received frequency. So, does Doppler effect give same frequencies for both the cases or is there a way to perceive the difference? The principle of relativity is one of the most basic assumptions built in to standard physics. Fundamentally, it says that there's no single choice of a "correct" state of motion, which means that there cannot be any "experiment the bodies themselves can do to determine which one is moving" because there is no correct answer to that question — the only things that matter are relative velocities (because there is no such thing as "absolute" velocity). The issue of "which one is moving" depends on which frame you're in, and any frame is as correct as any other frame. So that's why the answer to the main question is "NO".
But there's another different question here, having to do with the Doppler effect in air, and it brings up an interesting subtlety. Only relative velocities matter, but now you have three things — the two bodies and the air — and the relative velocities between each pair of them will come into the physics. In principle, you could decide if one is at rest relative to the air. But there's nothing absolute about the air; it's just another object in physics. The wind could start to blow, and now suddenly the other object might be the one that's at rest relative to the air. Moreover, someone could drive by and decide that all three are moving with respect to her. But the principle of relativity says that she should be able to calculate the Doppler shift and — assuming she correctly accounts for the fact that the air is moving relative to her — get the right answer.
The following is multiple choice question (with options) to answer.
What is a measure of both speed and direction of motion? | [
"intensity",
"velocity",
"distance",
"acceleration"
] | B | Velocity is a measure of both speed and direction of motion. Velocity is a vector, which is a measurement that includes both size and direction. |
SciQ | SciQ-3333 | zoology, experimental
Title: Fish "coming back to life" after being frozen I've encountered a clip on Youtube showing a goldfish thrown in liquid nitrogen and immediately after to normal water and swimming normally. In the explanation to the clip it says:
For everyone that is worried about the goldfish, it survived and was perfectly fine until we fed him and a few of his friends to our turtles. (Which is what they were bought for in the first place!)
I am wondering now as to several issues.
If the goldfish wasn't fed to the turtles and was allowed to live out its life, would it suffer any long term damages from the act?
Is time an issue here, if the fish was kept frozen for a longer time, would it suffer more damage and would it be able to be revived?
Is the size and nature of the fish's body a factor? Would a larger animal or an animal with better resistance to frost that would take more time to completely freeze have damage due to gradual freezing of body and systems?
Does the fact that fish have cold blood affect the result of the experiment? I have no idea what's the real reason for the survival of the poor fish, but I would guess this is all in the timing. I know for certain ;-) that one can submerge a hand in liquid nitrogen for a short time or in general one can pour liquid nitrogen on the skin with no harm done whatsoever.
The reason is that the difference in temperature that interface (-180 deg C or so for liquid nitrogen and 20-30 for the skin surface) is so large that nitrogen vaporizes instantly and does not penetrate/affect the tissue. The demonstrator could have pulled the fish with bare hands.
I think that for the goldfish the time was too short and while it was cooled/shocked a bit, it might have been too short to do any serious damage. But -
As a scientist, I can't help but notice that we don't really know the condition of the fish before or after the liquid nitrogen 'treatment'. We only see it flapping for a few seconds when back in water. I wonder what happened to the eyes and the mouth, both quite sensitive tissues for such a shock. Also, the water the fish was in was a factor probably, providing additional buffer between the fish and the liquid nitrogen.
Last but not least, the ethical committee quite certainly did not approve that demonstration.
The following is multiple choice question (with options) to answer.
What do fish eggs hatch to form? | [
"adolescent fish",
"unfertilized eggs",
"fish eggs hatch to form larvae",
"tadpoles"
] | C | Almost all fish have sexual reproduction, generally with separate sexes. Most fish are oviparous. Many species reproduce by spawning. Eggs hatch to form larvae, which undergo metamorphosis to become adults. |
SciQ | SciQ-3334 | botany, plant-physiology, ecology, virology, host-pathogen-interaction
Note about symbiosis - comes in reaction to @Gerhard's comment
Different authors use the word symbiosis differently. From wikipedia:
The definition of symbiosis is controversial among scientists. Some believe symbiosis should only refer to persistent mutualisms, while others believe it should apply to any type of persistent biological interaction (i.e. mutualistic, commensalistic, or parasitic).4 After 130+ years of debate,5 current biology and ecology textbooks now use the latter "de Bary" definition or an even broader definition (i.e. symbiosis = all species interactions), with the restrictive definition no longer used (i.e. symbiosis = mutualism)
The following is multiple choice question (with options) to answer.
Commensalism, mutualism, and parasitism are known as what type of relationships? | [
"peculiar",
"symbiotic",
"various",
"simple"
] | B | 19.4 Community Ecology Communities include all the different species living in a given area. The variety of these species is referred to as biodiversity. Many organisms have developed defenses against predation and herbivory, including mechanical defenses, warning coloration, and mimicry. Two species cannot exist indefinitely in the same habitat competing directly for the same resources. Species may form symbiotic relationships such as commensalism, mutualism, or parasitism. Community. |
SciQ | SciQ-3335 | quantum-mechanics, atomic-physics, spectroscopy, hydrogen, orbitals
Title: Is the atomic shell model valid considering electron-electron interaction? In atomic physics the shell model is motivated by starting looking at the H-atom. Solving Schrödinger's equation leads to atom orbitals labled by quantum numbers n,l,m. Taking Pauli's principle into account it is said that that atom can be 'build up' by filling the shells considering Hund's rules. After that the state of an atom can be written in spectroscopic notation as $^{2S+1}L_J$ and transitions by selection rules. But in this model the electromagnetic interaction between the electrons are neglected cause the shells are filled only taking the quantum numbers into account. My questions is how valid this is because for example a transision is only determined by allowed changes of quantum numbers which are only well defined for a seperation ansatz $\Psi(\vec{r},t)=R_{nl}(r)Y_{lm}(\phi,\theta)$ but this can only be applied for the H-atom. It depends a bit on what you mean by 'the shell model'.
If you mean that you take the hydrogenic wavefunctions (perhaps scaled to the nuclear charge) and then populate them with the chosen number of electrons, then that is obviously going to be a terrible description of reality. Nobody does that, and nobody would really consider that as a serious model of the atom.
Instead, the shell model really refers to a more sophisticated approach, which is more often called the Hartree-Fock self-consistent-field method.
The following is multiple choice question (with options) to answer.
The modern model of the atom, which scientists call the quantum mechanical model, is based on what scientist's work on orbitals? | [
"Newton",
"schrödinger",
"Bohr",
"Sagan"
] | B | Schrödinger’s work on orbitals is the basis of the modern model of the atom, which scientists call the quantum mechanical model. The modern model is also commonly called the electron cloud model. That’s because each orbital around the nucleus of the atom resembles a fuzzy cloud around the nucleus, like the ones shown in the Figure below for a helium atom. The densest area of the cloud is where the electrons have the greatest chances of being. |
SciQ | SciQ-3336 | units, si-units, metrology
Title: How units were defined? I was wondering how we humans can be sure that one meter is one meter and that one second is one second. Nowadays, except for the Kilogram, all other units are well defined using highly accurate techniques (frequency of atoms vibrations or stuff like that). But at the end all units are kind of related to each other and the definition of each unit is based on a combination of other units. There must be some viable sources that have constant measurable values that we used to define the basic units. What is those sources?
To explain more let's start with the meter. From wikipedia, the definition is: The metre is the length of the path travelled by light in vacuum during a time interval of 1/299,792,458 of a second. So here it is clear that the definition of a meter relies on the accuracy of how we define a second.
Now let's look at the second:
the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
How is this period calculated? The sensor has probably some equations that imply transformations using other units like Kg etc...
Where does this loop stops?
EDIT:
I think I was a little bit mistaken. Not all units are directly related and there is 3 totally independent units which are : Time (second), Temperature (kelvin) and Mass (kilogram). Time and Temperature are well defined but Kilogram is still unclear. Every existing unit can be transformed into a combination of those three. It means that all units based on Kilogram are not absolute. In short, up until now, the $kg$ was arbitrary, but now people are trying to define it based on universal constants
There is a ongoing process to try and link all the units to universal constants.
This has been done already for the second (using Cesium) and the meter (using the speed of light in a vacuum)
However, the kilogram is a little less straightforward. An interesting read is SI units revision proposal.
It proposes to link the kg to the Plank constant $h$, but also to link Kelvin $K$ to the Stefan-Boltzman constant $k$ and more of these constructions.
The following is multiple choice question (with options) to answer.
Time, mass, length, and temperature are considered to be what kinds of units? | [
"unitary",
"support",
"base",
"measurement"
] | C | Base units have independent scales and cannot be described by a combination of any other base units. Examples of base units used in chemistry are length, mass, temperature, and time. |
SciQ | SciQ-3337 | thermodynamics, statistical-mechanics, temperature
Air is not an ideal gas. The most important factor is that air usually contains a non negligible amount of water vapor, the presence of which can greatly change its thermodynamic properties
In the atmosphere, wind is actually a large mass of air moving from regions of higher pressure to regions of lower pressure. Such a mass of air can be colder than the surrounding air, so the presence of wind can actually be linked to a decrease in temperature. The discussion becomes much more complicated in this cases, and a full understanding of it would require some knowledge of atmospheric science.
The following is multiple choice question (with options) to answer.
What does the heat energy affect in the atmosphere? | [
"erosion and condensation",
"winds and weather",
"gravity and precipitation",
"density and humidity"
] | B | How do the differences in energy striking different latitudes affect Earth? The planet is much warmer at the equator than at the poles. In the atmosphere, the differences in heat energy cause winds and weather. On the surface, the differences cause ocean currents. Can you explain how?. |
SciQ | SciQ-3338 | 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 are the taste receptors found as tiny bumps on the tongue called? | [
"ear buds",
"taste buds",
"fat buds",
"hard buds"
] | B | Taste receptors are found in tiny bumps on the tongue called taste buds (see Figure below ). There are separate taste receptors for sweet, salty, sour, bitter, and meaty tastes. The meaty taste is called umami . You can learn more about taste receptors and the sense of taste by watching the animation at the following link: http://www. bbc. co. uk/science/humanbody/body/factfiles/taste/taste_ani_f5. swf . |
SciQ | SciQ-3339 | organic-chemistry, biochemistry, carbohydrates
Title: Is formaldehyde a carbohydrate? Formaldehyde has the formula $\ce{CH2O}$, and the ratio of atoms in a simple carb is $\ce{1C:2H:1O}$. This fits the formula of carbohydrates. When I researched this, I found some sources saying that formaldehyde is the simplest carb, but other sources saying it is glycolaldehyde ($\ce{C2H4O2}$). Is formaldehyde a carbohydrate? According to IUPAC definition:
‘carbohydrate’ includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups to carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom, an amino group, a thiol group or similar heteroatomic groups. It also includes derivatives of these compounds [...]
But according to Wikibooks
the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons. Natural saccharides are generally built of simple carbohydrates called monosaccharides with general formula $\ce{(CH2O)_n}$ where $n$ is three or more [...]
Because formaldehyde and glycolaldehyde (not a true sugar) has one and two carbon respectively in its structures we can exclude both as a carbohydrate.
The following is multiple choice question (with options) to answer.
What is the chemical formula for a glucose molecule? | [
"d5 h12 o6",
"c6 h12 o6",
"H2 C3 NA6",
"a5 h12 o6"
] | B | The sugar glucose is a covalent compound. When sugar dissolves in water, it forms individual glucose molecules (C 6 H 12 O 6 ). You can see how this happens in the Figure below . Sugar is polar like water, so sugar molecules also have positive and negative ends. Forces of attraction between oppositely charged ends of water and sugar molecules pull individual sugar molecules away from the sugar crystal. Little by little, the sugar molecules are separated from the crystal and surrounded by water. You can watch this happening in the video at the following URL: http://www. youtube. com/watch?v=hydUVGUbyvU. |
SciQ | SciQ-3340 | quantum-mechanics, schroedinger-equation
Title: Applying the Schroedinger equation I hope this isn't a dumb question, but...
If we have two fixed sine waves, both of which have a frequency range of +1 to -1, with a ratio between the waves of wave(1):3 to wave(2): 1, what does the Schrodinger equation tell us (if anything) about the relationship between the waves?
Equally, if the waves are no longer fixed (ie, time dependent) and wave(1) has complete nine oscillations, what does Schrodinger predict about the relationship between the waves for oscillation number 10? The Schroedinger equation is a dynamical equation that predicts the time evolution of a quantum system. Since it sounds like the time evolution of your system is externally imposed, the schroedinger equation doesn't make any predictions about it.
Your question is analogous to saying, "I define a particle trajectory in 1D, $x(t)$ for $0<t<T_{\mathrm{max}}$. What does $F=ma$ tell us about the trajectory? What does the trajectory do for $T_{\mathrm{max}} < t < T_{\mathrm{max}} + \Delta T$?"
The following is multiple choice question (with options) to answer.
In physics, the number of waves that pass a fixed point in a given amount time is referred to as what ? | [
"combination frequency",
"wave frequency",
"wave count",
"creation frequency"
] | B | Wave speed is related to both wavelength and wave frequency. Wavelength is the distance between two corresponding points on adjacent waves. Wave frequency is the number of waves that pass a fixed point in a given amount of time. This equation shows how the three factors are related:. |
SciQ | SciQ-3341 | inorganic-chemistry, reactivity
Title: Why does potassium react more violently with water than lithium? Recently, I was telling my friends about the violent reaction that takes place when you throw potassium into water. Soon after, a friend of mine claimed that lithium would react more violently than potassium.
I disagreed with him, because potassium is more electropositive than lithium and thus more reactive.
My friend claimed lithium to be more reactive than potassium due to its position in the reactivity series of metals:
$$\ce{Li > Cs > Rb > K > Ba > Sr > Ca > Na > Mg}$$
Then we found out that potassium reacts indeed more violently in water.
But what about his argument? Why isn't he right? For the reaction,
$$\ce{M -> M+ + e-}$$
the heat liberated is highest for lithium owing to its high negative $E^\circ$ value so one would think that the reaction must be most vigorous.
The reason behind the more violent reactivity of potassium rather than lithium lies in kinetics and not in thermodynamics.
No doubt, maximum energy is evolved with lithium but the vaporization and ionization will also consume maximum energy (the melting point and ionization energy of lithium are the highest) and so the reaction proceeds gently. On the other hand, potassium has a lower melting point and ionization enthalpy. The heat of reaction is sufficient to melt it. The molten metal spreads over the water and exposes a larger surface to water. Also, the hydrated radius of lithium is the greatest out of all alkali metals. This reduces the ionic mobility which in turn reduces the speed of the molten metal.
That's why potassium gives a more violent reaction with water.
Reference:
Kumar, Prabhat Conceptual Inorganic Chemistry; Shri Balaji Publications: Muzaffarnagar, U.P., 2014.
The following is multiple choice question (with options) to answer.
The reactions between alkali metals and water are particularly vigorous and include the rapid production of large quantities of what gas? | [
"oxygen",
"hydrogen",
"carbon",
"helium"
] | B | All alkali metals are very soft and can be cut easily with a knife. Due to their high reactivity, they must be stored under oil to prevent them from reacting with oxygen or water vapor in the air. The reactions between alkali metals and water are particularly vigorous and include the rapid production of large quantities of hydrogen gas. Alkali metals also react easily with most nonmetals. All of the alkali metals are far too reactive to be found in nature in their pure elemental form. For example, all naturally occurring sodium exists as a compound, such as sodium chloride (table salt). |
SciQ | SciQ-3342 | electricity, electrons, voltage, batteries, electrochemistry
Title: How batteries create voltage? I am trying to have a more fundamental understanding of electricity and specifically what voltage is.
My memory of highschool physics was that a battery has an excess of electron on one terminal, and a shortage on the other. This explanation caused some confusion when I thought about batteries in series; why does two 1,5V batteries add to 3V.
If it is excess and shortage of electrons, created from a chemical reaction, that attract the electrons from cathode to anode, wouldn't the volt (J/C) be the same for a circuit with two batteris; every electron in the cathode has one void to fill in the anode?
Some reading lead me to see battery voltage as a measurement of how much energy per electron (J/C) the chemical reaction produces, and the number of reactions per second as the current (C/s). I know 1 coulomb is not 1 electron, and one reaction doesn't necessarily = 1 free electron, this is a rough picture in my mind.
Does this mean that it is the energy released from the reaction that is accelerating the electron a certain amount depending on the amount of energy, and how is it that two batteries accelerate the electron twice as much?
This is my first attempt at articulation my confusion, so I'm sorry that this is not as eloquent as it could be Voltage (up to a factor) is the work one electron can produce when travelling from anode ($-$) to cathode ($+$). Current is the number of electrons flowing.
The energy needed to do the work comes from the energy released when electron participates in the reaction happening at cathode. This is chemistry-specific, so one cell of a battery has usually a very specific voltage.
Now imagine what happens if you have two cells in series. When, electron travels from A2 to C1 it produces work $W$ and when it reaches $C1$ it releases energy $U$. But at the same time, it allows another electron to travel from $A1$ to $C2$ and release another chunk of energy $U$. So in the end, $W=U+U=2U$ and we say that two cells in series have twice as large voltage, meaning for every electron participating in outer current, there is now twice as many reactions.
The following is multiple choice question (with options) to answer.
Batteries produce voltage through what type of reaction? | [
"chemical",
"magnetic",
"thermal",
"radiation"
] | A | Chemical cells are found in batteries. They produce voltage by means of chemical reactions. A chemical cell has two electrodes, which are strips made of different materials, such as zinc and carbon (see Figure below ). The electrodes are suspended in an electrolyte. An electrolyte is a substance containing free ions that can carry electric current. The electrolyte may be either a paste, in which case the cell is called a dry cell, or a liquid, in which case the cell is called a wet cell. Flashlight batteries contain dry cells. Car batteries contain wet cells. Animations at the URL below show how batteries work. |
SciQ | SciQ-3343 | thermodynamics, statistical-mechanics
I have now shown that temperature is a macroscopic concept because I have only needed macroscopic physical ideas and quantities (energy, entropy, mass, volume) to define and describe it precisely.
It remains to say how temperature relates to microscopic behaviours and quantities. To find out the temperature of a collection of small things such as atoms or molecules or vibrations or whatever, the mathematical method amounts, in the end, to finding out the entropy and using equation (2) or (3). In many cases it turns out that the temperature is closely related to the mean kinetic energy of the parts of the system, but in order to say this in a quantitative way one has to be quite careful in deciding how the parts are being counted. But temperature is not a property of a single atom or a single vibration or a single rotation. It is a collective property, like an average. If atoms in a gas are moving around and colliding with one another, then at any given time some atoms will be moving fast, with lots of energy, and some will be slow, with little energy. But we should not say that in this case some atoms are hot and some cold. Rather, the temperature is a property of the distribution of energy. It is a measure of how quickly the number of atoms at a given energy falls off as a function of energy, when the atoms are continuously exchanging energy with one another through collisions. (This measure is somewhat related to the average energy per particle but they are not quite the same.)
Relating temperature to energy
Here is a further comment on the relationship between temperature and energy, suitable for school-level study. For many simple systems it happens that the entropy goes up in proportion to the logarithm of the energy, as long as the temperature is high enough:
$$
S \propto \log U
$$
with a proportionality constant of order $R$ (the gas constant):
$$
S \simeq R \log U .
$$
This implies that the energy is proportional to the exponential of the entropy:
$$
U = A e^{S/R}
$$
where $A$ is a constant. In this case
$$
\frac{dU}{dS} = \frac{1}{R} A e^S = \frac{U}{R}
$$
so using equation (2) we find
$$
The following is multiple choice question (with options) to answer.
The speed of a particle in what state is directly proportional to the temperature of the system? | [
"liquid",
"frozen",
"solid",
"gas"
] | D | The speed of a gas particle is directly proportional to the temperature of the system. |
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