source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-5344 | solid-state-physics, molecules
The band structure in Carbon comes from 2p electrons on the individual carbon atoms which are aligned perpendicularly to the planes of the carbon sheets. The bonding of these 2p electrons can be seen on the left hand side in Benzene molecules with the hexagonal structure - 6 atomic orbitals contribute to make 3 bonding and 3 antibonding molecular orbitals.
The bonding orbitals ($\pi$) are filled with 6 electrons (the arrows) and the antibonding levels ($\pi^*$) are empty. Now on the right handside of the diagram many 2p orbitals from many carbon atoms combine to form the bonding (mostly filled) and antibonding (mostly empty) bands of graphite.
Now you could look at the energies of the electron states and say that we have non-integer $n$ values, but I think it makes more sense to think of the electron states being spread over many many atoms and having different (integer) numbers of nodes in the wavefunctions over a larger number of atoms.
The following is multiple choice question (with options) to answer.
What type of electrons does carbon have? | [
"ionic",
"shell",
"gradient",
"valence"
] | D | Carbon is a nonmetal in group 14 of the periodic table. Like other group 14 compounds, carbon has four valence electrons. Valence electrons are the electrons in the outer energy level of an atom that are involved in chemical bonds. The valence electrons of carbon are shown in Figure below . |
SciQ | SciQ-5345 | human-biology, eyes, vision, human-eye
Title: Superhuman eyesight My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was lying as he reeled off the whole number plate and not just some. My husband went across the road to prove him wrong and get him to admit he was making it up but he wasn't. We even asked people in the restaurant and waiting staff for their opinion and everyone was blown away. I'm totally astonished and slightly freaked out by his sight and I'm hoping someone can explain for me.
Specifics
The following is multiple choice question (with options) to answer.
What do doctors call farsightedness or the inability to see close objects clearly? | [
"hyperopia",
"myopia",
"hypopia",
"dysarthria"
] | A | Farsightedness is also known as hyperopia . It affects about one fourth of people. People with hyperopia can see distant objects clearly, but nearby objects appear blurry. In hyperopia, the eye is too short. This results in images being focused in back of the retina ( Figure above ). Hyperopia is corrected with a convex lens, which curves outward like the outside of a bowl. The lens changes the focus so that images fall on the retina as they should. |
SciQ | SciQ-5346 | population-genetics
Title: Average and lowest degrees of kinship/consanguinity among humans? I would appreciate insight into the average, median, RMS or any similar measure of relatedness among the current world population - and perhaps something about how rapidly this may be changing. A similar question is how un-related any two humans can be: i.e., what is the lowest degree of consanguinity between the two most distantly related people. The context is an exploration of how humans have evolved tendencies toward racism and other in/outgroup distinctions, when all humans share such a large fraction of DNA with each other, very nearly as much with non-human primates, and about half even with fruit flies. Might be some helpful lessons in there!
Apologies if the question is ill-formed, or answer readily available someplace - I've browsed the Web for several years on this topic, and found nothing I could understand..
Accessible material about most recent common ancestor and identical ancestor point seems to indicate a wide range of both methodologies and results, based mainly on statistical simulations since "hard" genetic structures apparently do not persist. MRCA datings based on mitochondrial and other genetics seem to line up with human behavioral modernity, ca. 200 kya. But there seem to be extreme estimates as recent as 2.3 kya, which implies a lot of mobility and high fertility by some not-so-distant forebears (like Genghis Khan). In any case, IAP may be a better starting point for this shared-anncestry question.
I'm guessing that no human is further than about a 10th~12th cousin to any other. Can't be more that 32nd, since 2^33 is more than the number of living humans!
All thoughts, including guesses more informed than mine, will be appreciated.
~ ~ ~ ~ ~
Addendum - tried to post this as an answer, but it was deleted:
MANY thanks to Zo-Bro-23 for the time, effort and creativity to create his response. I hope it is well-indexed for future explorers to find!
In case useful or interesting to anyone,or sparks further contributions, here were/are my main motivations for this inquiry:
The following is multiple choice question (with options) to answer.
What type of simple inheritance is too simplified to explain most human traits? | [
"spontaneous mutation",
"mendelian",
"etiology",
"mitosis"
] | B | Most human traits have more complex modes of inheritance than simple Mendelian inheritance. For example, the traits may be controlled by multiple alleles or multiple genes. |
SciQ | SciQ-5347 | nuclear-physics, astrophysics, sun, fusion, stellar-physics
Basically, the Sun is a ball of hydrogen and helium, but this is not all there is. Being a Population I star, the Sun contains heavier elements (called metals in stellar astrophysics; anything lithium and heavier is considered metal in this sense). These elements already came with the gas cloud the Sun has formed from, and were produced by previously burst older stars. Despite low abundance, the metallicity plays an important role in the Sun's core power stability.
At some depth the gas ball compresses its inner area enough to heat it up so much that hydrogen fusion into helium begins. This area is called the core. This is where practically all fusion happens, and what is responsible for the star's energy production. For a Sun-mass star and below, the proton-proton chain dominates. The pp-chain energy output is approximately proportional to $T^4$. The good news is, if reaction rate drops, then the outer layer of the star will compress the core, so it heats up, and the renewed energy output compensates for the compression. So this highly-sensitive dependency on the temperature is what gives the star its long term stability.
It is also notable that the center of the core is hotter and therefore more energetic than its periphery, and turns hydrogen into helium faster. Absent any mixing, the core would develop an inert helium ball in the middle (helium cannot be fused by a Sun-mass star, its core is too cold for that): A pp-chain core is entirely non-convective. However, there is another multistage reaction that fuses protons into helium nuclei, the CNO cycle. This cycle requires metals ($C$, $N$ and $O$, naturally) be present in the core. They are not consumed, but participate in stages of the reaction and are ultimately recycled. The rate of this reaction depends on the temperature as $T^{20}$. It's a huge dependency! The CNO-dominant core has so much temperature gradient that it's fully convective, so it mixes the material very thoroughly.
The following is multiple choice question (with options) to answer.
The sun emits energy in the form of what? | [
"particles radiation",
"mechanical radiation",
"microwave radiation",
"electromagnetic radiation"
] | D | Figure 5.10 The sun emits energy in the form of electromagnetic radiation. This radiation exists in different wavelengths, each of which has its own characteristic energy. Visible light is one type of energy emitted from the sun. |
SciQ | SciQ-5348 | inorganic-chemistry
Title: Why do metals tend to lose electrons, as opposed to maintaining electric neutrality? Metals tend to lose electrons to obtain the stable noble gas configuration of 8 valence electrons.
Why do they want to obtain this configuration, and how does the strength of their "desire" to obtain this configuration compare with the "desire" to maintain neutral charge. If the answer depends on the chemical, I'm happy for you to provide some examples.
Thanks. Firstly, atoms "want" to achieve the noble gas configuration of 8 valence electrons because it is the most stable form. All that means is that it doesn't tend to react under normal conditions that we experience on Earth, therefore it will stay in that configuration for quite a while and are less likely to react. There is a more complex quantum physical answer for that but you'll have to go elsewhere for than.
The main force that keeps electrons in atoms is the electrical attraction between the electrons and the protons in the nucleus and so, if it is more energetically favourable to lose that electron in order to form a bond, then that is what will happen.
Focusing on the Alkali metals as an example, as you move down the group, they get more and more reactive. This is because of two main reasons that are a result of the electrons being further away from the nucleus:
Because they're further away, the attraction between the protons and the outer most electron is less
Secondly, taking Rubidium as an example, it has 37 electrons and 37 protons. From the perspective of the outer-most electron, there are 36 electrons repelling it, and 37 protons attracting it, therefore acting as a net charge of 1. However, if you take into account the first point, the repulsion of the closer electrons is stronger than the attraction of the protons so it could even be less than one
The following is multiple choice question (with options) to answer.
The number of electrons in the outer energy level determines what property of nonmetals? | [
"permeability",
"reactivity",
"vibration",
"density"
] | B | Some nonmetals are very reactive, whereas others are not reactive at all. It depends on the number of electrons in their outer energy level. |
SciQ | SciQ-5349 | acid-base, hydrogen, protons
Title: Is water hydronium and hydroxide? In our chemistry lesson when learning about the Bronsted-Lowry definition for acids and bases, we came across the reaction...
H2O + H2O -> H3O+ + OH-
...Where water is amphiprotic which means it acts as an acid and base. Does this mean that water is a combination of hydronium and hydroxide? How is it not harmful to drink then? If there are arrows going both ways then that means it’s in equilibrium between the right side (products) and the left side (reactants).
It doesn’t mean that water is a mix of H3O+ and -OH, a vast majority of water will stay H2O, and the small amount of H3O+ or -OH wouldn’t be anywhere near a concentration to hurt you
I think the purpose of that was to show that water has the potential to form H3O+ and -OH in itself in an attempt to teach you about acid base equilibrium
The following is multiple choice question (with options) to answer.
Acids are the opposites of what? | [
"gas",
"bases",
"water",
"solids"
] | B | Acids and bases have had many uses throughout history. In this chapter we want to explore the properties of acids and bases and the reactions in which they take part. |
SciQ | SciQ-5350 | 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.
What is the process in which gases are exchanged between the body and the outside air? | [
"ingestion",
"precipitation",
"respiration",
"metabolism"
] | C | Respiration is the process in which gases are exchanged between the body and the outside air. The lungs and other organs of the respiratory system bring oxygen into the body and release carbon dioxide into the atmosphere. |
SciQ | SciQ-5351 | water, phase
Title: Does autoionization occur in steam? It is well known that H2O spontaneously autoionizes to H+ and OH- when it is in liquid phase. I was wondering whether it does the same in gas phase, either to the same extent as in liquid phase or at all. Yes, water is ionized to some extent in all phases. One study even extends to 1,000 K!
A concise discussion of the change in ionization with temperature at Chemguide also explains the variation of pH of neutral water with temperature. [The concept of pH 7 being neutral is based on Kw (in mol2 dm-6) of ~10-14 at ~300 K.]
In general, the higher the temperature, the more a compound is ionized.
The following is multiple choice question (with options) to answer.
Steam consists of what common and essential element in its gaseous phase? | [
"water",
"air",
"carbon dioxide",
"plasma"
] | A | |
SciQ | SciQ-5352 | dna, rna, virus, virology, gene
Title: Is there any virus that contains both DNA and RNA in its genome? It is known that viruses contain DNA or RNA- either one and not both.
I came across a question: Which virus contains both DNA and RNA? Here is the results summary of the study that describes the discovery of DNA:RNA hybrid virus:
Results
Bioinformatic analysis of viral metagenomic sequences derived from a hot, acidic lake revealed a circular, putatively single-stranded DNA virus encoding a major capsid protein similar to those found only in single-stranded RNA viruses. The presence and circular configuration of the complete virus genome was confirmed by inverse PCR amplification from native DNA extracted from lake sediment. The virus genome appears to be the result of a RNA-DNA recombination event between two ostensibly unrelated virus groups. Environmental sequence databases were examined for homologous genes arranged in similar configurations and three similar putative virus genomes from marine environments were identified. This result indicates the existence of a widespread but previously undetected group of viruses.
And here is the link to the paper:
https://biologydirect.biomedcentral.com/articles/10.1186/1745-6150-7-13
The following is multiple choice question (with options) to answer.
The capsid is made from the what that are encoded by viral genes within their genome? | [
"acids",
"proteins",
"lipids",
"hormones"
] | B | Viruses vary in their structure. A virus particle consists of DNA or RNA within a protective protein coat called a capsid. The shape of the capsid may vary from one type of virus to another. The capsid is made from the proteins that are encoded by viral genes within their genome. |
SciQ | SciQ-5353 | isomers
(5) $\ce{CH3CH2CH(CH3)-O-CH3}$ :methyl sec-butyl ether
(6) $\ce{(CH3)3-C-O-CH3}$ : methyl tert-butyl ether
The following is multiple choice question (with options) to answer.
Methane, ethane, and propane are three of the smallest what? | [
"microorganisms",
"atoms",
"alkanes",
"organisms"
] | C | The three smallest alkanes are methane, ethane, and propane. Some hydrocarbons have one or more carbon–carbon double bonds (denoted C=C). These hydrocarbons are called alkenes. http://catalog. flatworldknowledge. com/bookhub/reader/2547 - gobch04_s06_f02shows the formulas and the molecular models of the two simplest alkenes. Note that the names of alkenes have the same stem as the alkane with the same number of carbon atoms in its chain but have the ending -ene. Thus, ethene is an alkene with two carbon atoms per molecule, and propene is a compound with three carbon atoms and one double bond. Figure 4.7 Formulas and Molecular Models of the Two Simplest Alkenes. |
SciQ | SciQ-5354 | quantum-mechanics, newtonian-mechanics
Title: What happens to a radioactive element or isotope's electrons when it undergoes alpha decay? It seems to make sense that when an atom loses two protons, it would lose two electrons as well, but I don't actually know what happens. It is complicated and we ignore it, but your intuition is right. When the nucleus loses an alpha particle its charge decreases by two. The atomic physicists now claim their job is done and don't care. The solid state physicists don't consider radioactivity, so they don't care either. If it is an atom floating freely in space, two electrons will move off in some direction, but who cares? If it is an atom in a solid crystal, you should ask how much the recoil moves the atom and whether it dislocates the crystal.
The following is multiple choice question (with options) to answer.
The number of neutrons and electrons may vary or change in an atom. what happens to the number of protons? | [
"remains the same",
"increases",
"decreases",
"depends"
] | A | The number of protons per atom is always the same for a given element. However, the number of neutrons may vary, and the number of electrons can change. |
SciQ | SciQ-5355 | biophysics, theoretical-biology, ecosystem
Systems ecology, especially with regard to energy and nutrient flow.
This type of ecology can be strongly influenced by physics. For one example see the book Theoretical Ecosystem Ecology: Understanding Element Cycles by Ågren & Bosatta (Ågren was originally a physicist)
Physical limitations to growth and transport
This can include for instance mechanical contraints on plant growth (see e.g. the book Plant Physics by Nicklas & Spatz), water transport in trees (see e.g. this BioSE question) or the biomechanics of movement (see e.g. Hudson et al (2012) on the speed and movement of cheetahs or Wikipedia: Biomechanics).
Allometric relationships between organisms, e.g. with regard to metabolism
To explain these types of relationships knowledge in physics is useful. See e.g. Kleiber's law for more.
MAXENT as a general approach to ecological patterns or to model species distributions
This is basically a tool lifted from physics that can be applied to ecological problems. There are many papers to look at, but Harte & Newman (2014) (Harte is another previous physicist) and Elith et al (2010) are two good starting points.
Dynamical modelling of populations and communities
This field use many of the same tools for analysis as physics, e.g. systems of differential equations. One of the pioneers in this field (among many) were Robert May (also started with a PhD in physics), and his classical book Theoretical Ecology: Principles and Applications is still a good starting point.
Energy harnessing and conversion by organisms
This can refer both to how organsims convert prey to energy (e.g. conversion efficiencies) and the physics of photosynthesis (which is an interesting intersection between physics and molecular biology). See Jang et al (2004) and O'Reilly & Olaya-Castro (2013) for examples of the how quantum mechanics can inform us about photosynthesis.
Hopefully this will give you a sense of some different ways that knowledge in physics can be useful for biology.
The following is multiple choice question (with options) to answer.
In biological augmentation, ecologists use what to add essential materials to ecosystems? | [
"fluids",
"sediments",
"organisms",
"stem cells"
] | C | |
SciQ | SciQ-5356 | optics, waves, diffraction
Title: Interference in diffraction gratings I am currently studying the Wikipedia article for diffraction grating, and am having difficulty understanding some of the information in the theory of operation section of the article.
An idealised grating is made up of a set of slits of spacing $d$, that must be wider than the wavelength of interest to cause diffraction. Assuming a plane wave of monochromatic light of wavelength $\lambda$ with normal incidence (perpendicular to the grating), each slit in the grating acts as a quasi point-source from which light propagates in all directions (although this is typically limited to a hemisphere). After light interacts with the grating, the diffracted light is composed of the sum of interfering wave components emanating from each slit in the grating. At any given point in space through which diffracted light may pass, the path length to each slit in the grating varies. Since path length varies, generally, so do the phases of the waves at that point from each of the slits. Thus, they add or subtract from each other to create peaks and valleys through additive and destructive interference. When the path difference between the light from adjacent slits is equal to half the wavelength, $\dfrac{\lambda}{2}$, the waves are out of phase, and thus cancel each other to create points of minimum intensity. Similarly, when the path difference is $\lambda$, the phases add together and maxima occur. The maxima occur at angles $\theta_m$, which satisfy the relationship $d \sin(\theta_m) = |m|$, where $\theta_m$ is the angle between the diffracted ray and the grating's normal vector, and $d$ is the distance from the center of one slit to the center of the adjacent slit, and $m$ is an integer representing the propagation-mode of interest.
(By Vigneshdm1990 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=58383485.)
The following is multiple choice question (with options) to answer.
What kind of interference is observed when the paths differ by a whole wavelength, and the waves arrive in phase? | [
"spontaneous interference",
"constructive interference",
"necessary interference",
"non-interference"
] | B | To understand the double slit interference pattern, we consider how two waves travel from the slits to the screen, as illustrated in Figure 27.13. Each slit is a different distance from a given point on the screen. Thus different numbers of wavelengths fit into each path. Waves start out from the slits in phase (crest to crest), but they may end up out of phase (crest to trough) at the screen if the paths differ in length by half a wavelength, interfering destructively as shown in Figure 27.13(a). If the paths differ by a whole wavelength, then the waves arrive in phase (crest to crest) at the screen, interfering constructively as shown in. |
SciQ | SciQ-5357 | c#, object-oriented
//Check for Fish nearby
direction = fishNearBy(x, y, sharkScent);
Debug.WriteLine("direction: " + direction);
if (direction == 0)
direction = rnd.Next(1, 5);
{
switch (direction)
{
case 1://East. If Index 0 move to TableEnde
if (newY > 0)
{
newY = newY - 1;
moved = true;
}
else
{
newY = TableY - 1;
moved = true;
}
break;
case 2://West. If TableEnde move to 0.
if (newY < TableY - 1)
{
newY = newY + 1;
moved = true;
}
else
{
newY = 0;
moved = true;
}
break;
case 3://North. If top reached try again
if (newX > 0)
{
newX = newX - 1;
moved = true;
}
break;
case 4://South. If bottom reached try again
if (newX < TableX - 1)
{
newX = newX + 1;
moved = true;
}
break;
default:
break;
}//switch
}//if
if (myArray[newX, newY].fishType == fishTypeEnum.fish)
{
Debug.WriteLine("Fisch gefangen");
eatFish(newX, newY);
myArray[x, y].ageStarvation = 0; ;
}
if (moved)
{
Debug.WriteLine("Hai bewegen");
myArray[newX, newY].cellColor = myArray[x, y].cellColor;
myArray[newX, newY].fishType = myArray[x, y].fishType;
myArray[newX, newY].age = myArray[x, y].age + 1;
myArray[newX, newY].ageStarvation = myArray[x, y].ageStarvation + 1;
myArray[newX, newY].moved = true;
The following is multiple choice question (with options) to answer.
What are mudskipper fish able to do in short distances? | [
"run",
"tumble",
"spit",
"walk"
] | D | Thomas H Brown. Mudskippers are fish that are able to walk short distances . CC-BY 2.0. |
SciQ | SciQ-5358 | pathology
Title: Are all diseases caused by organisms (microorganisms)? Are there other causes? Or is it correct to say that all diseases are in fact caused by organisms (microorganisms)? It is not correct to say that all diseases are caused by foreign organisms. Counterexamples are:
Cancer is caused by random genetic mutations in the cells of our body. The mutations can be caused by many factors such as ionizing radiation, smoking, chemical toxins etc.
Diseases such as stroke or heart attack are caused by blood clots blocking the blood flow to essential organs.
Autoimmune diseases are caused by the immune system falsely recognizing cells of the body as foreign and attacking that tissue leading to a wide variety of symptoms.
Alzheimer's disease is caused by chronic neurodegeneration, meaning that the cells in the brain die. The causes are not quite understood but as Alzheimer's usually appears late in life it is likely related to ageing. Also, it is known that some genetic defects can lead to early-onset Alzheimers.
Prion proteins can cause diseases such as Creutzfeldt–Jakob disease also known as mad-cow disease.
Hereditary diseases such as early-onset Alzheimers or ALS are cause by gene defects inherited from the parents.
Toxins can cause chronic diseases such as lead poisoning.
The list probably goes on...
Please note that the first two on the list are the most common cause of death in developed countries.
The following is multiple choice question (with options) to answer.
What is the major cause of disease in agricultural crops? | [
"pollution",
"bacteria",
"drought",
"fungi"
] | D | Some fungi have a different kind of relationship with plants. They are plant parasites. They get food from the plants and cause harm to the plants in return. Fungi are the major causes of disease in agricultural crops. They may eventually kill their plant hosts. |
SciQ | SciQ-5359 | mycology
Title: How do fairy rings propagate? It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, but what has been bizarre to me is how fairy rings form. Why do the fruiting bodies arrange themselves in a more or less circular shape, as opposed to the random scattering one would expect from wind-borne spores? When a fungal spore germinates in a suitable location, the growing mycelium will spread underground in all directions. In the ideal situation, the result is that the mycelium will become circular. Over time, the center of the mycelium will die out whereas the newly formed mycelium (underground) will develop the familiar mushrooms above ground and this will result in a fairy ring.
The following is multiple choice question (with options) to answer.
What type of reproduction occurs in almost all fungi? | [
"fragmentation",
"asexual",
"budding",
"sexual"
] | D | Sexual reproduction also occurs in virtually all fungi. This involves mating between two haploid hyphae. During mating, two haploid parent cells fuse, forming a diploid spore called a zygospore . The zygospore is genetically different from the parents. After the zygospore germinates, it can undergo meiosis, forming haploid cells that develop into new hyphae. |
SciQ | SciQ-5360 | 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 protists absorb food molecules across their cell membranes? | [
"solid",
"fibrous",
"absorptive",
"dielectric"
] | C | Absorptive protists absorb food molecules across their cell membranes. This occurs by diffusion . These protists are important decomposers. |
SciQ | SciQ-5361 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
How do dogs lose body heat? | [
"panting",
"eating",
"barking",
"sweating"
] | A | One way mammals lose excess heat is by increasing blood flow to the skin. This warms the skin so heat can be given off to the environment. That’s why you may get flushed, or red in the face, when you exercise on a hot day. You are likely to sweat as well. Sweating also reduces body heat. Sweat wets the skin, and when it evaporates, it cools the body. Evaporation uses energy, and the energy comes from body heat. Animals with fur, such as dogs, use panting instead of sweating to lose body heat (see Figure below ). Evaporation of water from the tongue and other moist surfaces of the mouth and throat uses heat and helps cool the body. |
SciQ | SciQ-5362 | cell-biology, cellular-respiration, mitochondria
Title: Electron Transport Chain in Mitochondria I was researching cellular respiration, and this is a rather confusing part. I need help understanding the purpose of Complex II and how the ATP Synthase generates the energy to turn ADP to ATP. The good ol'electron transport chain (ETC).
Before beginning let us begin by looking at the structure of a mitochondrion and the purpose of the ETC.
(source: tokresource.org)
Take of note four things:
The intermembrane space
The matrix
The electron transport chain proteins and
ATP Synthase
Now lets talk about the purpose of the ETC, essentially its job is to create a H+ (proton) gradient between the intermembrane space and the matrix it does this by taking protons from the matrix and "pumping" them out to the intermembrane space.
This creates a higher concertation in the intermembrane space and lower concertation in the matrix. This gradient will result in a process called chemiosmosis where these H+ ions (protons) will go through ATP synthase on the inner plasma membrane in order to return to the lower concentration in the matrix.
So the most important thing to note about this is that the flow of protons through the ATP Synthase is what gives it the energy necessary to create ATP.
Alright now that is out of the way lets discuss how the ETC goes about pumping these electrons out of the matrix into the intermembrane as well as how ATP Synthase works.
If you were to zoom into the area that is labeled electron transport chain proteins (that I told you to note) you would see something like this.
(source: cnx.org)
What we see here is that ETC is actually made up of a series of complexes (I, II, III, and IV) and a couple of "electron/reaction" carriers (ubiquinone and cyt c). These complexes and carriers are in charge of moving an electron via a series of redox reaction along resulting in the "pumping" of protons out the matrix at each complex.
*Note, understanding redox reactions help in understanding what is happening here.
The chemistry gets a little intense at this point, so I'm going to quote and link the Wikipedia article on this, which does a wondrous job explaining what occurs complex to complex.
The following is multiple choice question (with options) to answer.
The electron transport chains are located on the inner membrane of which organelle? | [
"chloroplast",
"axon",
"lysosome",
"mitochondrion"
] | D | High-energy electrons are released from NADH and FADH 2 , and they move along electron transport chains, like those used in photosynthesis. The electron transport chains are on the inner membrane of the mitochondrion. As the high-energy electrons are transported along the chains, some of their energy is captured. This energy is used to pump hydrogen ions (from NADH and FADH 2 ) across the inner membrane, from the matrix into the intermembrane space. Electron transport in a mitochondrion is shown in Figure below . |
SciQ | SciQ-5363 | soil
An analogous hypothesis proposed by RUSSEL3 for increases in the number of bacteria after partial sterilization by heat, frost, or other means is that by such partial sterilization the protozoa are killed, thus permitting the unhindered development of bacteria which under normal conditions is held in check by protozoa.
BROWN and SMITH (loc. cit.) in their investigations dealt mainly with the physiological activities of bacteria under conditions of low temperature and frost, although they also made some determinations of the number of bacteria in frozen soil. Their principal conclusions regarding the ammonifying, nitrifying, denitrifying, and nitrogen fixing powers of frozen soils are as follows: (1) that "frozen soils possess a much greater ammonifying power than unfrozen soils"; (2) that "during the fall season, the ammonifying power of the soil increases until the temperature of the soil almost reaches zero, when a decrease occurs, and this is followed by a gradual increase and the ammonifying power of the soil reaches a maximum at the end of the frozen period"; (3) that "the nitrifying power of frozen soils is weak and shows no tendency to increase with extension of the frozen period"; (4) that "frozen soils possess a decided denitrifying power which seems to diminish with the continuance of the frozen period"; (5) that "during the fall season, the denitrifying power of the soil increases until the soil freezes, after which a decrease occurs"; (6) that "frozen soils possess a nitrogen fixing power which increases with the continuance of the frozen period, being independent of moderate changes in the moisture conditions, but restricted by large decreases in moisture"; and (7) that "in the fall, the nitrogen fixing power of the soil increases until the soil becomes frozen, which in almost ceases, after which a smaller nitrogen fixing power is established."
The following is multiple choice question (with options) to answer.
What happens to growth of plants and bacteria in warmer regions? | [
"they are stunted",
"they mutate",
"they grow slower",
"they grow faster"
] | D | In warmer regions, plants and bacteria grow faster. Plants and animals weather material and produce soils. In tropical regions, where temperature and precipitation are consistently high, thick soils form. Arid regions have thin soils. |
SciQ | SciQ-5364 | electromagnetism, electromagnetic-radiation, magnetic-fields
The answer will be not complete without electromagnetic radiation. It was observed that a periodically changed electric current (in an antenna rod) lead not only to a induced time varying magnetic field but - if the power of the antenna generator is high enough - to a remarkable electromagnetic radiation. Accelerating electrons, this electrons emitting a part of their energy as electromagnetic radiation. It was observed that this radiation has an electric and a magnetic field component. In the near field of the antenna the electric field bears (induces) a magnetic field. The magnetic field induces an electric field and so on and this happens with a propagation velocity of - naturally - the speed of light. Electromagnetic radiation is caused by electrons (or other particles) but once emitted the periodical occurring electric and magnetic fields are self-propagating and not more related to any particle.
The following is multiple choice question (with options) to answer.
Electromagnetic waves are generally caused by magnetic fields doing what (or moving in what way)? | [
"revolving",
"vibrating",
"rippling",
"folding"
] | B | An electromagnetic wave begins when an electrically charged particle vibrates. The Figure below shows how this happens. A vibrating charged particle causes the electric field surrounding it to vibrate as well. A vibrating electric field, in turn, creates a vibrating magnetic field. The two types of vibrating fields combine to create an electromagnetic wave. You can see animations of electromagnetic waves at these URLs:. |
SciQ | SciQ-5365 | human-biology, cell-biology, tissue, tissue-repair
Shining light on skin pigmentation: the darker and the brighter side
of effects of UV radiation.
Melanocyte biology and skin pigmentation.
Melanosome Degradation: Fact or Fiction
The following is multiple choice question (with options) to answer.
Exposure to what can increase the amount of pigment in the skin and make it appear darker? | [
"sunlight",
"gamma rays",
"nuclear radiation",
"ultraviolet radiation"
] | D | Genes are a major determinant of human skin color. However, exposure to ultraviolet radiation can increase the amount of pigment in the skin and make it appear darker. |
SciQ | SciQ-5366 | oceanography, geochemistry
Title: Why is NaCl so hyper abundant in the ocean? Why is sodium chloride far and away the most abundant salt dissolved in ocean water? Its two constituent ions do have a very high frequency in the crust of the earth, but they are far from the most common. Chlorine is (according to Wikipedia) the 21st most abundant element, and sodium 6th.
I certainly understand that a combination of their solubility and reasonably high frequency would lead one to expect them to be abundant in sea water, but they are hyper abundant, completely dominating all other salt ions. Iron, for example, is twice as abundant, and potassium only a little less abundant, and fluorine more abundant than chlorine.
Moreover, if the salts are deposited in the ocean through weathering of rocks and deposition via rivers, why does the salinity not simply grow and grow? I understand that some is lost due to tectonic activity, but it seems extraordinarily unlikely that these two forces should be equally balanced, and so we would see a significant change in average salinity over time.
(Please note I am migrating this question from the Chemistry SE at their recommendation.) Fluoride salts tend to be not particularly soluble in water. Chloride salts are. The same goes for salts containing sodium versus those containing calcium. Sodium chloride is ridiculously easy to dissolve.
Regarding your second question, it is geological forces that keep salinity more or less constant. People formerly argued that the Earth can't be more than a few hundred million years old because otherwise the river waters running into the oceans would eventually result in an insanely high salinity. It turns out that the Earth's oceans are young (young compared to the 4.5 billion year age of the Earth). The vast majority of oceanic crust is less than 100 million years old. We see huge salt deposits sprinkled across the world because those are the dried up remnants of former seas and oceans. Salt is also drawn into the Earth at subduction zones, where it combines chemically with basalt.
The following is multiple choice question (with options) to answer.
Most of the trash in the ocean is made of what material? | [
"wood",
"styrofoam",
"hydrocarbons",
"plastic"
] | D | Much of the trash in the oceans is plastic. Many types of plastic do not degrade. Some break down into plastic molecules, but these can also be a pollutant. Plastic shopping bags are extremely abundant in the oceans. Since water runs from land into the sea, chemicals can end up in the sea. Pesticides, herbicides, and fertilizers are among the chemicals. |
SciQ | SciQ-5367 | 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.
What is the name of the glands that produce milk in female mammals ? | [
"fetal glands",
"mammary glands",
"recombinant glands",
"sebaceous glands"
] | B | Female mammals have mammary glands . The glands produce milk after the birth of offspring. Milk is a nutritious fluid. It contains disease-fighting molecules as well as all the nutrients a baby mammal needs. Producing milk for an offspring is called lactation . |
SciQ | SciQ-5368 | neuroscience, cardiology, action-potential
Title: Do nerve cells cause action potential in cardiac muscle? I think the answer is no, but I am not 100% sure.
If it was yes, then the dendrite of the nerve cell should each time receive a stimulus causing Na+ channels to open, when the contraction happen.
Also, then it would mean that outside events could alter the function of hearth, which would be dangerous.
The heart has a special excitatory system and a contractile system - Sinoatrial node and Pacemaker cells, which control the action potentials in different portions of the heart.
So heart and primarily myocardium i.e. cardiac muscle can depolarise without any external influence with a slow, positive increase in voltage across the cell's membrane.
Do nerve cells cause action potential in cardiac muscle? The vagus nerve controls heart rate. This is the best example of a direct nerve action potential impacting cardiac muscle, although one could argue the adrenaline system to be an indirect mechanism.
The vagus nerve is part of the parasympathetic system, it acts to decrease heart rate. Resting heart rate is maintained by permanent vagal stimulation/tone by the release of acetylcholine.
The following is multiple choice question (with options) to answer.
The conductive cells within the heart establish the heart rate and transmit it through the what? | [
"conduction",
"myocardium",
"meiosis",
"neurons"
] | B | 19.2 Cardiac Muscle and Electrical Activity The heart is regulated by both neural and endocrine control, yet it is capable of initiating its own action potential followed by muscular contraction. The conductive cells within the heart establish the heart rate and transmit it through the myocardium. The contractile cells contract and propel the blood. The normal path of transmission for the conductive cells is the sinoatrial (SA) node, internodal pathways, atrioventricular (AV) node, atrioventricular (AV) bundle of His, bundle branches, and Purkinje fibers. The action potential for the conductive cells consists of a prepotential phase with a slow influx of Na+ followed by a rapid influx of Ca2+ and outflux of K+. Contractile cells have an action potential with an extended plateau phase that results in an extended refractory period to allow complete contraction for the heart to pump blood effectively. Recognizable points on the ECG include the P wave that corresponds to atrial depolarization, the QRS complex that corresponds to ventricular depolarization, and the T wave that corresponds to ventricular repolarization. |
SciQ | SciQ-5369 | optics, vision
Title: Insides of eyelids and light People commonly see the insides of their eyelids and see a little amount of light and no amount of light of the insides of their eyelids depending on what environment they're in, What's the difference of seeing the amount of light of the insides of their eyelids? Your eyelids are partially transparent to light. In the presence of a strong light source, even with eyes closed some light will make it through. Usually it will be reddish after passing through the skin filled with blood vessels.
You may also see greenish, yellowish, magenta, or purplish images that fade after closing your eyes. These are called after-images and are the result of the chemicals in your retina resetting themselves after light is removed. They typically consist of cyan, magenta, and yellow which are are opposite colors of your cone receptors: red, green, and blue.
The following is multiple choice question (with options) to answer.
What is the opening in the front of the eye? | [
"the cornea",
"the iris",
"the macula",
"the pupil"
] | D | The pupil is an opening in the front of the eye. It looks black because it doesn’t reflect any light. It allows light to enter the eye. The pupil automatically gets bigger or smaller to let more or less light in as needed. |
SciQ | SciQ-5370 | inorganic-chemistry, transition-metals, oxidation-state
Title: Anomalous oxidation states of Transition Metals
I have noted down the available positive oxidation states of the first
row of transition elements (on the Periodic Table) from the respective Wikipedia articles of
the elements.
$\ce{Sc} - 3, 2,1$
$\ce{Ti} - 4, 3, 2, 1 $
$\ce{V} - 5, 4, 3, 2, 1$
$\ce{Cr} - 6, 5, 4, 3, 2, 1$
$\ce{Mn} - 7, 6, 5, 4, 3, 2, 1$
$\ce{Fe} - 6,5,4,3,2,1 $
$\ce{Co} - 5,4,3,2,1 $
$\ce{Ni}- 4,3,2,1$
$\ce{Cu} - 4,3,2,1$
$\ce{Zn} - 2,1$
The following is multiple choice question (with options) to answer.
Binary transition-metal compounds, such as the oxides and sulfides, are usually written with idealized what? | [
"fluctuations",
"speciation",
"noble gases",
"stoichiometries"
] | D | VII *The convention of using roman numerals to indicate the oxidation states of a metal is used here. Binary transition-metal compounds, such as the oxides and sulfides, are usually written with idealized stoichiometries, such as FeO or FeS, but these compounds are usually cation deficient and almost never contain a 1:1 cation:anion ratio. Thus a substance such as ferrous oxide is actually a nonstoichiometric compound with a range of compositions. The acid–base character of transition-metal oxides depends strongly on the oxidation state of the metal and its ionic radius. Oxides of metals in lower oxidation states (less than or equal to +3) have significant ionic character and tend to be basic. Conversely, oxides of metals in higher oxidation states are more covalent and tend to be acidic, often dissolving in strong base to form oxoanions. |
SciQ | SciQ-5371 | 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.
What disease refers to the dangerous buildup of fatty materials in blood vessels? | [
"fibrosis",
"gout",
"atherosclerosis",
"arthritis"
] | C | A unique mutation is found in people in a small town in Italy. The mutation protects them from developing atherosclerosis, which is the dangerous buildup of fatty materials in blood vessels. The individual in which the mutation first appeared has even been identified. |
SciQ | SciQ-5372 | 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.
Which nerve directly stimulates the contraction of skeletal muscles in the pharynx and larynx to contribute to the swallowing and speech functions? | [
"gland nerve",
"glands nerve",
"vagus nerve",
"larynx nerve"
] | C | Nerves of the Face and Oral Cavity An iconic part of a doctor’s visit is the inspection of the oral cavity and pharynx, suggested by the directive to “open your mouth and say ‘ah. ’” This is followed by inspection, with the aid of a tongue depressor, of the back of the mouth, or the opening of the oral cavity into the pharynx known as the fauces. Whereas this portion of a medical exam inspects for signs of infection, such as in tonsillitis, it is also the means to test the functions of the cranial nerves that are associated with the oral cavity. The facial and glossopharyngeal nerves convey gustatory stimulation to the brain. Testing this is as simple as introducing salty, sour, bitter, or sweet stimuli to either side of the tongue. The patient should respond to the taste stimulus before retracting the tongue into the mouth. Stimuli applied to specific locations on the tongue will dissolve into the saliva and may stimulate taste buds connected to either the left or right of the nerves, masking any lateral deficits. Along with taste, the glossopharyngeal nerve relays general sensations from the pharyngeal walls. These sensations, along with certain taste stimuli, can stimulate the gag reflex. If the examiner moves the tongue depressor to contact the lateral wall of the fauces, this should elicit the gag reflex. Stimulation of either side of the fauces should elicit an equivalent response. The motor response, through contraction of the muscles of the pharynx, is mediated through the vagus nerve. Normally, the vagus nerve is considered autonomic in nature. The vagus nerve directly stimulates the contraction of skeletal muscles in the pharynx and larynx to contribute to the swallowing and speech functions. Further testing of vagus motor function has the patient repeating consonant sounds that require movement of the muscles around the fauces. The patient is asked to say “lah-kah-. |
SciQ | SciQ-5373 | dna, chromosome
Chromosome is a highly coiled structure of DNA molecule. Often observed in X-shaped only. Along with DNA, some proteins are also make up chromosomes.
But Why does DNA need to be coiled tightly into chromosomes?
DNA double helix is like a telephone wire. If length is to be measured, it will go beyond 60 miles. Some even say it can make a trip to the moon more than 150,000 times. Such a long DNA molecule is not only the part of each organism's cell nucleus but also it's invisible to the naked eye. This happens just because of the high packaging and coiling of this long DNA molecule.
Let's see the diagram to get an idea.
At the bottom of the diagram there is a sequence of nucleotides (ATGC) in different combinations. This can be considered as a gene if it codes for certain protein which is required for the growth or any other function of the body.
Returning back to your question, Complimentary base pairs are not genes.
Genes are the segments of DNA which is a long sequence of nucleotide base pairs that code for any protein or RNA transcript that contributes to any trait/phenotype/function of an individual.
With the tight packaging of DNA double helix along with help of packaging proteins(Histones and Non-histones), the chromatid and chromosomes are made. The packaging of DNA to chromosomes is highly controlled and is a whole different topic in itself.
The following is multiple choice question (with options) to answer.
What do we call coiled structures made of dna and proteins? | [
"nodes",
"chromosomes",
"Organisms",
"Molecules"
] | B | Chromosomes are coiled structures made of DNA and proteins. They form after DNA replicates and are the form in which the genetic material goes through cell division. Chromosomes contain genes, which code for proteins. |
SciQ | SciQ-5374 | quantum-mechanics, energy, hilbert-space
Title: Discrete energies allowed for a particle in a box For a cubic box the energy of a particle is given by:
$$ E = \frac{\pi^2 \hbar^2}{2mL^2} [n_1^2+n_2^2+n_3^2]$$
It is possible that $E$ has the same value for different combinations of $n_1, n_2$ and $n_3$.
I have read that when there are states with the same energy, this energy level is said to be degenerated.
Does this mean that the probability to get this level is $0$? Degeneracy means, an energy-level can be occupied by different combinations of quantum number $n_i$. So you are correct in this point.
But this means, there are multiple eigenstates with the same value, so their probability is the same for every eigenstate and not $0$.
A more thorough explanation can be found here.
The following is multiple choice question (with options) to answer.
Energy comes in discrete packages called what? | [
"quota",
"quasi",
"quasar",
"quanta"
] | D | Energy comes in discrete packages called quanta. |
SciQ | SciQ-5375 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
Which type of cell can carry out more functions, eukaryotic cells or prokaryotic cells? | [
"chromosomal cells",
"eukaryotic cells",
"both",
"Prokaryotic Cells"
] | B | In addition to having a plasma membrane, cytoplasm, a nucleus and ribosomes, eukaryotic cells also contain membrane-bound organelles . Each organelle in a eukaryote has a distinct function. Because of their complex level of organization, eukaryotic cells can carry out many more functions than prokaryotic cells. The main differences between prokaryotic and eukaryotic cells are shown in Figure below and listed in Table below . Keep in mind that some eukaryotic cells may have characteristics or features that other eukaryotic cells lack, such as the cell wall. |
SciQ | SciQ-5376 | physiology, cardiology, blood-circulation, circulatory-system
Title: Why does higher venous volume increase atrial pressure? If the cardiac output stays the same (hypothetically, although obviously it doesn't stay the same), then why does higher venous volume increase right atrial pressure? Shouldn't the flow rate be conserved (with a constant cardiac output) so that the venous return to the right atrium is no different than before, and therefore the pressure is no different? Imagine the circulatory system is an amusement park ride. The ride is the left ventricle and the arterial system. After riding, people go around and get back in line to go again. The line and the building housing it are the venous system. Maybe the lungs are some sort of staging area where you get ready to get on the ride.
The right atrium is the end of the venous system. Venous pressures are right atrial pressure.
When all is well the line is moderate and people wait a short time before riding again. But now 100 more people arrive. If the park workers can speed up the ride or loading rate to accommodate the extra riders then great. But if the ride cannot go any faster then the line backs up. If you imagine that it is raining out, all the people in line bunch into the building housing it. Venous pressure increases. It will stay increased unless the number of riders (blood volume) decreases or the heart improves its output to accommodate the load.
Congestive heart failure is a useful example. The ride speed (cardiac output) cannot increase because the heart is weak. If riders increase (blood volume) it backs up into the waiting line or venous system. This increase in volume occurs if someone with CHF eats a salty meal – water follows salt and blood volume increases, which backs up in the venous system because the heart cannot increase its output to accommodate the increased volume. These sick folks are said to be volume overloaded. You can see increased venous pressure as the signs of CHF – for example dilated external jugular veins.
Among many adaptations to deal with increased venous pressure is atrial natriuretic peptide. When increased venous pressure stretches the right atrium this peptide hormone is secreted which is a cue to the kidney to dump sodium, and with it fluid volume.
The following is multiple choice question (with options) to answer.
When vascular disease causes stiffening of arteries, compliance is reduced and resistance to blood flow is increased. the result is more turbulence, higher pressure within the vessel, and reduced blood flow. this increases the work of this? | [
"heart",
"muscles",
"lung",
"brain"
] | A | Compliance Compliance is the ability of any compartment to expand to accommodate increased content. A metal pipe, for example, is not compliant, whereas a balloon is. The greater the compliance of an artery, the more effectively it is able to expand to accommodate surges in blood flow without increased resistance or blood pressure. Veins are more compliant than arteries and can expand to hold more blood. When vascular disease causes stiffening of arteries, compliance is reduced and resistance to blood flow is increased. The result is more turbulence, higher pressure within the vessel, and reduced blood flow. This increases the work of the heart. |
SciQ | SciQ-5377 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
Animals that do not have internal control of their body temperature are called what? | [
"photophores",
"athermal",
"cold-blooded",
"ectotherms"
] | D | Thermoregulation Animals can be divided into two groups: those that maintain a constant body temperature in the face of differing environmental temperatures, and those that have a body temperature that is the same as their environment and thus varies with the environmental temperature. Animals that do not have internal control of their body temperature are called ectotherms. The body temperature of these organisms is generally similar to the temperature of the environment, although the individual organisms may do things that keep their bodies slightly below or above the environmental temperature. This can include burrowing underground on a hot day or resting in the sunlight on a cold day. The ectotherms have been called cold-blooded, a term that may not apply to an animal in the desert with a very warm body temperature. An animal that maintains a constant body temperature in the face of environmental changes is called an endotherm. These animals are able to maintain a level of activity that an ectothermic animal cannot because they generate internal heat that keeps their cellular processes operating optimally even when the environment is cold. |
SciQ | SciQ-5378 | optics
Title: light accumulation in an optic fibre If we send light down an optic fibre and loop the fibre back onto itself, with just an opening for our light source, would the light (photons) accumulate within the fibre?
If so then to what extent would they accumulate and can it be calculated?
Would this be the bandwidth of the fibre? Yes, you can create a 'ring' with optical fiber, with a coupling section to add photons in. You can keep adding photons until the (non-linear) loss mechanisms balance the input. This can be estimated, but is hard to calculate from first principles because you don't know all the parameters for the actual assembled setup. This has nothing in particular to do with the bandwidth of the fiber, although where your laser is with respect to the loss profile vs wavelength impacts the loss mechanisms.
The following is multiple choice question (with options) to answer.
What do optical fibres look like? | [
"thin glass tubes",
"big flashlights",
"flat paper",
"square boxes"
] | A | Besides entertaining a cat, laser light has many other uses. It is used to scan bar codes, for example, and to carry communication signals in optical fibers. Optical fibers are extremely thin glass tubes that are used to guide laser light (see Figure below ). Sounds or pictures are encoded in pulses of laser light, which are then sent through an optical fiber. All of the light reflects off the inside of the fiber, so none of it escapes. As a result, the signal remains strong even over long distances. More than one signal can travel through an optic fiber at the same time, as you can see in Figure below . Optical fibers are used to carry telephone, cable TV, and Internet signals. |
SciQ | SciQ-5379 | genetics
Title: What distinguishes Mendelian Inheritance from Non-Mendelian Inheritance? I'm having some trouble determining what exactly is the difference between Mendelian inheritance and non-Mendelian inheritance. For instance, I understand that chromosomal abnormalities such as Down's Syndrome fall under non-Mendelian inheritance because they concern chromosomes, not single genes. And I also understand that Mendelian inheritance concerns single genes, as in Sickle-cell anemia (which is an autosomal recessive disorder).
What confuses me is the fact that our textbook discusses dihybrid and trihybrid (concerning 2 genes and 3 genes, respectively) crosses under the Mendelian inheritance chapter, when to me it seems like these crosses are non-Mendelian because they deal with multiple genes. However, Gregor Mendel did in fact use the dihybrid cross to deduce the law of independent assortment, so I'm completely confused. Could someone please clarify this for me? I'm afraid that I'm maybe misinterpreting something. You can discuss multiple genes within the framework of Mendelian inheritance; what you're probably thinking of, though, is the fact that Mendelian inheritance doesn't recognize the idea of multiple genes that contribute to a single trait.
For example, if there is a gene that controls petal color (blue vs. white, with blue = dominant) and a gene that controls height (short vs. tall, with tall = dominant), then Mendelian inheritance predicts that two short plants with white flowers will only produce short plants with white flowers.
But if there are multiple genes that interact to determine height in a complex way, that's outside the scope of Mendelian inheritance.
The following is multiple choice question (with options) to answer.
Genetics is the branch of biology that focuses on heredity in what? | [
"schools",
"organisms",
"vacuums",
"fruits"
] | B | Genetics is the branch of biology that focuses on heredity in organisms. |
SciQ | SciQ-5380 | molecular-biology, proteins, genetics, learning
Title: How do proteins and genes participate in learning? I am a computer scientist that studies biology and bioinformatics.
In the last weeks, I have been trying to study new research directions, and I would like to deepen my knowledge on the role and behavior of genes and proteins in learning.
By learning, I mean the human process: the information I is absent at time T, and present at time T+1.
I would like to study more this problem, and I am wondering: how do proteins and genes behave during learning?
I have read that proteins that participate in learning are called marker proteins. Is it true? Which role do they have?
Where could I find some resources to study this fascinating problem?
Thank you very much! The storage of memories in cells is rarely thought of on the protein level of the cell. Cells are usually given a developmental state, but no memory. A cell may become a liver cell, cancerous, or diabetic, but this is not memory, but a physiological change in the cell which is usually not reversible to a previous state.
For example cancer treatments are entirely focused on identifying the cancerous cells and killing them. Internally the genomes of cancer cells often have deletions and duplications. They are cancerous, they have not learned to be cancerous. Though not as dramatic, it is now thought that cellular differentiation which creates different types of cells is heavily influenced by epigenetic modification of the genome; the DNA is marked by methyl groups which dictates the state of the cell by modifying the gene. This is mediated by proteins for sure, but is quite complex and not well understood at this time. Epigenetic markers can even change gene behavior between generations of offspring as well, though that is not usually called memory.
How is information stored in the brain? This is thought to be reflected in the organization of the neurons in the brain. There are many kinds of neurons. They can be distinguished by the sorts of axons and dendrites that emanate from the cell body. They can also be distinguished by the chemical variety of neurotransmitter they use (there are a score of different molecules). So to a great extent the type of cell and the specific proteins it chooses to use to mediate information is very important.
The following is multiple choice question (with options) to answer.
What type of protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle? | [
"amino acid",
"conduction protein",
"membrane protein",
"rod protein"
] | C | The second main component of plasma membranes are the variety of proteins. A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. Membrane proteins can be put into two groups based on how the protein is associated with the membrane: (1) integral membrane proteins and (2) peripheral membrane proteins. |
SciQ | SciQ-5381 | thermodynamics, atoms, phase-transition
But let's look at how the states change. In a solid, you have a bunch of atoms that can be thought of as masses connected by springs. As heat is added to the system, the atoms begin to vibrate in the lattice of springs. As more heat is added, they vibrate enough to break the springs. This is when the solid begins to melt and turn to a liquid.
Now you have a liquid where the atoms are all moving around but they aren't free to move wherever they want. More heat is added to the system and the atoms begin to translate faster and faster. Eventually they translate fast enough to overcome the forces that are holding them together in a liquid. Now they fly free and are a gas.
So ultimately, heat is energy that makes atoms and molecules move in some way. They may translate, rotate, vibrate, or the electrons may begin moving around depending on how much heat is there and what configuration the molecule has.
The following is multiple choice question (with options) to answer.
What is defined as the ability to cause changes in matter? | [
"nuclear",
"momentum",
"evolution",
"energy"
] | D | Energy is defined as the ability to cause changes in matter. You can change energy from one form to another when you lift your arm or take a step. In each case, energy is used to move matter — you. The energy of moving matter is called kinetic energy . |
SciQ | SciQ-5382 | evolution, zoology, adaptation
One answer that came to mind is domestic animals - the horse and dog in prehistory, the cat in ancient Egypt, etc. That seems too obvious on one hand, and on the other hand may not really be an answer, as there seems to be no indication that pre-domestic animals were endangered by humans in any meaningful way. Are there animals that have significantly adapted themselves to surviving as wild animals in human-influenced environments? Note: This is an answer to the last line of your question.
A classical example of animals adapting to the influence of humans on their environment is the adaption of the Peppered Moth.
Here is a brief summary:
The peppered moth was originally a mostly unpigmented animal (<1800). During the industrial revolution in the southern parts of the UK a lot of coal was burned. This led to soot blackening the countryside. Soon afterwards, a fully pigmented variety was first observed. Only a hundred years later, in 1895, this pigmented variety almost completely displaced the unpigmented variety.
It has been shown that the pigmentation is under strong selective pressure as birds hunt these moths. Since birds rely on their visual system to detect their prey, the variety that blends in with its environment (=camouflage) has a selective advantage over the variety that stands out.
As pointed out by Tim in the comments, since the 1970s there has been a rapid reversal with unpigmented animals being more abundant. As far as I understand, it is accepted that this reversal is due to a decrease in human induced air pollution leading to less sooty barks on trees which makes the unpigmented variety harder to prey upon.
Addendum: genetic basis of adaption
In a beautiful recent study, the causal mutation for the pigmented, or melanic, variety was identified: A ~9kb transposon insertion in the first intron of the gene cortex. The authors calculate that this mutation happened in the year 1819, a few years after the industrial revolution was in full swing. The interpretation is that due to sooty tree bark this mutation, causing pigmented moth, was under strong selection.
The following is multiple choice question (with options) to answer.
What group of animals has permeable skin that makes them vulnerable to pollution? | [
"reptiles",
"mammals",
"amphibians",
"fish"
] | C | Amphibians have permeable skin that easily absorbs substances from the environment. This may explain why they seem to be especially sensitive to pollution. Monitoring the health and survival of amphibians may help people detect pollution early, before other organisms are affected. |
SciQ | SciQ-5383 | Now consider the second row of $$\C$$. This is a cosine sampled at horizontal axis values:
$\vec{t_1} \triangleq \left[ 2 \pi \frac{n}{N} \;\mathrm{for}\; n \in 0,1,\ldots,N-1 \right]$
Call $$t_{k, n}$$ the value of $$\vec{t_k}$$ at index $$n$$. Now consider the second column of $$\C$$. This is a cosine sampled at horizontal axis values for $$n = 1$$:
$\begin{split}t_{0,1} = (0) 2 \pi \frac{1}{N} \\ t_{1,1} = (1) 2 \pi \frac{1}{N} \\ ... \\ t_{N-1,1} = (N-1) 2 \pi \frac{1}{N} \\\end{split}$
In general, because the sequence $$k 0,1,,N-1$$ is equal to the sequence $$n \in 0,1,\ldots,N-1$$, this means that the column sampling positions for row $$n \in t_{0, n}, t_{1, n}, ... , t_{N-1, n}$$ are equal to the row sampling positions for corresponding ($$k = n$$) row $$k \in t_{k, 0}, t_{k, 1}, ... , t_{k, N-1}$$. Write column $$z$$ of $$\C$$ as $$C_{:,z}$$; column $$z$$ of $$\S$$ is $$S_{:, z}$$. Therefore $$C_{z, :} = C_{:, z}, S_{z, :} = S_{:, z}$$.
### Row dot products and lengths¶
The following is multiple choice question (with options) to answer.
A period is a horizontal row of the what? | [
"periodic table",
"species table",
"phases table",
"cycles table"
] | A | A period is a horizontal row of the periodic table. There are seven periods in the periodic table, with each one beginning at the far left. A new period begins when a new principal energy level begins filling with electrons. Period 1 has only two elements (hydrogen and helium), while periods 2 and 3 have 8 elements. Periods 4 and 5 have 18 elements. Periods 6 and 7 have 32 elements because the two bottom rows that are separated from the rest of the table belong to those periods. They are pulled out in order to make the table itself fit more easily onto a single page. |
SciQ | SciQ-5384 | atmosphere, carbon-cycle
Title: For a tree over its entire existence, does it actually have a net negative effect on atmospheric CO2? A tree while alive converts CO2 + water -> carbohydrates + O2. However, once the tree dies, it decays, releasing CO2 back into the atmosphere. My question is, over an individual tree's overall existence, does a tree actually contribute to a reduction in atmospheric CO2?
I'm aware there's other pathways a tree could end up as a more long term carbon store (carbonaceous rocks), but mostly interested in if a tree were to die and fall in a forest, decay in 50-150 years, would it have contributed to a net reduction in CO2, or does a tree typically act as more of a temporary 100+ year store of CO2? A brief review of recent non-paywalled available literature indicates that such an effect likely exists but that it is difficult to quantify based on currently available data.
Some amount of carbon from trees can be sequestered in the soil for periods time significantly longer than the typical above-ground decomposition time of organic matter, potentially for millennia. This clearly lengthens the carbon cycle time, but it is not clear to me whether this represents carbon storage, as there does not seem to be a well established minimum cut-off time for this. The primary source for soil-sequestered carbon are tree roots, with leaf litter constituting a secondary source.
The following paper (preprint online) addresses the question in the specific context of agroforestry, i.e. cropland interspersed with trees. The paper notes multiple times that the processes involved in soil sequestration are not well understood and that quantitative measurements and estimates vary widely, as one would expect based on differences in climatic and soil condition. Note on units: A Mg corresponds to a metric ton.
Klaus Lorenz and Rattan Lala, "Soil organic carbon sequestration in agroforestry systems. A review." Agronomy for Sustainable Development, Vol. 34, No. 2, April 2014, pp. 443-454.
The following is multiple choice question (with options) to answer.
What term refers to any method of removing carbon dioxide from the atmosphere and storing it in another form? | [
"carbon metamorphosis",
"carbon sequestration",
"carbon transfer",
"carbon footprint"
] | B | Carbon sequestration is any way of removing carbon dioxide from the atmosphere and storing it in another form. Carbon is sequestered naturally by forests. Trees take in carbon dioxide for photosynthesis. Artificial methods of sequestering carbon underground are being researched. |
SciQ | SciQ-5385 | 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 system protects the body from worms, germs, and other agents of harm? | [
"lymph system",
"immune",
"hormones",
"digestion"
] | B | The immune system protects the body from worms, germs, and other agents of harm. The immune system is like a medieval castle. The outside of the castle was protected by a moat and high stone walls. Inside the castle, soldiers were ready to fight off any invaders that managed to get through the outer defenses. Like a medieval castle, the immune system has a series of defenses. In fact, it has three lines of defense. Only pathogens that are able to get through all three lines of defense can harm the body. |
SciQ | SciQ-5386 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Most members of the animal kingdom have differentiated tissues of four main classes—nervous, muscular, connective, and this? | [
"digestive",
"neural",
"crystalline",
"epithelial"
] | D | ingest their food and usually develop into motile creatures with a fixed body plan. Most members of the animal kingdom have differentiated tissues of four main classes—nervous, muscular, connective, and epithelial—that are specialized to perform different functions. Most animals reproduce sexually, leading to a developmental sequence that is relatively similar across the animal kingdom. Organisms in the animal kingdom are classified based on their body morphology and development. True animals are divided into those with radial versus bilateral symmetry. Animals with three germ layers, called triploblasts, are further characterized by the presence or absence of an internal body cavity called a coelom. Animals with a body cavity may be either coelomates or pseudocoelomates, depending on which tissue gives rise to the coelom. Coelomates are further divided into two groups called protostomes and deuterostomes, based on a number of developmental characteristics. |
SciQ | SciQ-5387 | ecology, marine-biology, ichthyology, life-history
(American eel, Anguilla rostrata, picture from Wikipedia in public domain)
As a fun sidenote, captive eel can become very old, and earlier this year a more than 155-year-old European eel that was kept in a well died (see newsstory) - the oldest known eel from what I know. Eels were often put in wells because they were believed to keep the well water clean.
Semelpary is also found in other fish species, for instance in the Smelt (Osmeridae) family, where many species are fished commercially. Some (most?) species in the family have multiyear life histories, but some, e.g. the Delta smelt (Hypomesus transpacificus) only live for a single year. Similarly to Salmon, Smelt also migrate from sea to freshwater to spawn, i.e. an anadromous life history.
Overall, less than 1% of teleost fish are semelparous according to Finch (1994) - see link for more examples of semelparous fish species and background. However, this figure is most likely uncertain, given that we know very little about the life history of many marine species. In some cases, you can also find a range of life-history strategies from semelparous to partially or totally iteroparous within the same species, depending on ecological context. Nevertheless, the low overall proportion of semelparous fish means that semelpary is generally a rare life history strategy in human exploited fish species.
(Delta smelt, Hypomesus transpacificus, picture from Wikipedia in public domain)
The following is multiple choice question (with options) to answer.
Which ancient fish has just two living species and is at risk of extinction? | [
"squids",
"latimeria",
"hominids",
"coelacanths"
] | D | Coelacanths are ancient fish with just two living species. They are at risk of extinction because of their very small numbers. |
SciQ | SciQ-5388 | blood-circulation, blood-pressure, tissue
Title: Blood circulation and blood pressure in different tissues The volume of blood coursing the blood circulation is approximately five litres. A typical vein will stretch about eight times as much as corresponding artery. Because veins have high capacitance, large changes in blood volume have little effect on arterial blood pressure.
If the volume rise or falls, the elastic walls stretch or recoil, changing the volume of blood thus blood pressure in the nervous system.
What else tissues can we consider?
I am interested in blood circulation and blood pressures in different tissues. I'm not sure I understand your question very well-maybe try and rephrase it? As another example, low blood pressure in the kidneys is sensed by the juxtaglomerular apparatus which secretes renin into the circulation. Renin converts angiotensinogen (released by the liver) into angiotensin I. Angiotensin I is then converted into angiotensin II by angiotensin converting enzyme (this is the target of anti-hypertensives called ACE inhibitors) secreted by the lungs. Angiotensin II is a potent vasoconstrictor which directly increases the blood pressure (and hence glomerular filtration rate). Angiotensin II also causes the release of aldosterone which acts on the kidneys to re-absorb salt and water again all facilitating an increase in blood pressure. I hope I've answered your question, if not please edit the question so it very clear.
The following is multiple choice question (with options) to answer.
A decline in blood flow to what organs stimulates release of the enzyme renin, in turn stimulating the reabsorption of sodium and water? | [
"thyroids",
"kidneys",
"lungs",
"kidneys"
] | B | Kidneys The kidneys participate in several complex endocrine pathways and produce certain hormones. A decline in blood flow to the kidneys stimulates them to release the enzyme renin, triggering the renin-angiotensin-aldosterone (RAAS) system, and stimulating the reabsorption of sodium and water. The reabsorption increases blood flow and blood pressure. The kidneys also play a role in regulating blood calcium levels through the production of calcitriol from vitamin D3, which is released in response to the secretion of parathyroid hormone (PTH). In addition, the kidneys produce the hormone erythropoietin (EPO) in response to low oxygen levels. EPO stimulates the production of red blood cells (erythrocytes) in the bone marrow, thereby increasing oxygen delivery to tissues. You may have heard of EPO as a performance-enhancing drug (in a synthetic form). |
SciQ | SciQ-5389 | biophysics, chemical-compounds
Title: What causes anything to smell? We all know that we can see anything because of Light Absorption and all. We can hear things because of caused vibrations. But what makes an object smell? I read somewhere about the presence of odorous chemical compounds in the objects which makes them smell. Then, What gives smell to those odorous chemical compounds?
What gives smell to those odorous chemical compounds
Your nose and your brain. First of all, there are just some molecules flowing through your nose. There are many receptor neurons that react to those molecules and send "signals" to your brain. In the end, you smell something.
It's the same with light: light really is just an electromagnetic wave of certain wavelength and humans happen to have cells that react to such waves.
The following is multiple choice question (with options) to answer.
What common air pollutant is characterized by its sharp odor and often triggers asthma attacks? | [
"nitrogen dioxide",
"plant dioxide",
"pigment dioxide",
"Carbon Dioxide"
] | A | Nitrogen dioxide is a toxic gas with a sharp odor. It can irritate the eyes and throat and trigger asthma attacks. It is a major air pollutant. |
SciQ | SciQ-5390 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
In addition to a nucleus what do eukaryotic cells have? | [
"organelles",
"nutrons",
"electrons",
"protons"
] | A | Eukaryotic cells have a nucleus and membrane-bound structures called organelles. |
SciQ | SciQ-5391 | genetics, allele
Title: What is meant by 'identical alleles'? I read in my book that "two alleles are considered to be homozygous if they are identical". But at the same time I read the definition of allele to be:
genes which code for a pair of contrasting traits are called alleles
My doubt is that how can they be both contrasting (different) and identical (same) at the same time
What I think is that if homozygous is somehow a part of specific conditions in alleles then how can it be different from alleles itself. These are just issues with singular and plural and whether you refer to individual copies or categories/types.
Two of the same allele copies are the same allele (category/type). Two different alleles (copies) can also be different (categories/types).
In the context of a diploid individual, they have two instances of each gene so therefore two alleles; these alleles can be the same or different.
So you can say you have two "red flower" alleles, meaning two copies of the red flower allele. Or you can have a population that has two alleles for flower color: red flower alleles or white flower alleles.
The same is used in English for other things. You might say a farm grows two fruits, peaches and plums, and also that I have two fruits in my hand, both peaches. You need to use surrounding context to recognize whether copy or type is meant.
The following is multiple choice question (with options) to answer.
What term is used to describe a cross between two individuals that have different traits? | [
"assimilation",
"hybridization",
"purebreed",
"fraternization"
] | B | Mendel first worked with plants that differed in a single characteristic, such as flower color. A hybridization is a cross between two individuals that have different traits. A hybridization in which only one characteristic is examined is called a monohybrid cross . The offspring of such a cross are called monohybrids. Mendel noted that hybridizing true-breeding (P generation) plants gave rise to an F 1 generation that showed only one trait of a characteristic. For example, a true-breeding purple-flowering plant crossed with a true-breeding white-flowering plant always gave rise to purple-flowered hybrid plants. There were no white-flowered hybrids. Mendel wanted to know what happened to the white-flowers. If indeed a "heritable factor" for white-flower had disappeared, all future offspring of the hybrids would be purple-flowered - none would be white. To test this idea, Mendel let the F 1 generation plants self-pollinate and then planted the resulting seeds. |
SciQ | SciQ-5392 | human-biology, physiology, respiration, breathing, lungs
Title: Why does hyperventilation make you feel like you need to breathe more? Calm Clinic claims:
"The problem is that hyperventilation makes your body feel like you're not getting enough oxygen. Essentially, it makes you feel like you need to take deeper breaths and take in as much air as possible. This makes all of the symptoms of hyperventilation worse."
As far as I know, the brain controls breathing rate by measuring the amount of carbon dioxide in the blood. So is this true? If so, why? Hyperventilation alone does not cause you to feel that you're not getting enough oxygen. Rather, it's what causes hyperventilation that does that (thus resulting in hyperventilation.)
The Calm Clinic explains this quite well (while only mildly contradicting your quote):
During periods of intense anxiety, the body is sent into a state of fight or flight, when the brain signals to the body that danger is afoot. When this happens, you automatically start breathing quickly, as this oxygenates your blood and prepares your body to respond to a threat by fighting or fleeing. If the threat that has triggered your fight or flight response (whether real or imagined) persists, you’re likely to continue hyperventilating until you start to experience other unpleasant physical symptoms.
The focus of your question is
"...This makes all of the symptoms of hyperventilation worse." [emphasis mine]
You can hyperventilate by breathing too quickly or too deeply; either way, in people without underlying medical disorders, hyperventilation is usually caused by stress/anxiety. Anxiety makes your heart rate increase, and causes a perception of the need for more air (not the actual hyperventilation). It is often accompanied by some degree of chest tightness, which many people reasonable attribute to a problem with their heart. These things tend to cause more stress, so it's a cycle. The symptoms of hyperventilation are dizziness/lightheadedness, tingling in your hands/feet and around your mouth, and more but less common symptoms.
Under normal circumstances, hyperventilation leads to a period of decreased respiratory rate to allow for arterial blood to build up that critical buffer, HCO3.
Dealing with Anxiety Symptoms: Hyperventilation
(written for laypersons)
The following is multiple choice question (with options) to answer.
What also happens when people feel anxious and breathe too fast? | [
"they become pettite",
"they become lightheaded",
"they become elated",
"they become hostile"
] | B | Sometimes people who are feeling anxious breathe too fast and become lightheaded. This is called hyperventilation. Hyperventilation can upset the pH balance of the blood, resulting in blood that is too basic. Explain why. |
SciQ | SciQ-5393 | human-anatomy
Taken from here such people would be able to dislocate then get their hands in front and relocate.
The body can be trained to be quite flexible through training like gymnastics etc...
The following is multiple choice question (with options) to answer.
Which two systems together provide support to the body and allow for movement? | [
"skeletal and muscular",
"muscular and nervous",
"skeletal and digestive",
"vascular and muscular"
] | A | 16.5 | Musculoskeletal System By the end of this section, you will be able to: • Discuss the axial and appendicular parts of the skeletal system • Explain the role of joints in skeletal movement • Explain the role of muscles in locomotion The muscular and skeletal systems provide support to the body and allow for movement. The bones of the skeleton protect the body’s internal organs and support the weight of the body. The muscles of the muscular system contract and pull on the bones, allowing for movements as diverse as standing, walking, running, and grasping items. Injury or disease affecting the musculoskeletal system can be very debilitating. The most common musculoskeletal diseases worldwide are caused by malnutrition, which can negatively affect development and maintenance of bones and muscles. Other diseases affect the joints, such as arthritis, which can make movement difficult and, in advanced cases, completely impair mobility. Progress in the science of prosthesis design has resulted in the development of artificial joints, with joint replacement surgery in the hips and knees being the most common. Replacement joints for shoulders, elbows, and fingers are also available. |
SciQ | SciQ-5394 | ngs, genomics, cancer
Title: Difference between copy number neutral reads and active reads In this paper, the authors talk about copy number neutral reads (as reads that equally represent parental chromosomes) and active reads (as reads from only one parent chromosome):
We reasoned that the reads mapped into a genomic window can be partitioned in two sets: one set includes reads that equally represent parental chromosomes (copy number neutral reads); and the other set contains reads from only one parent chromosome (active reads).
Nonetheless, I have some difficulties understanding these two concepts. Can somebody try to expand on what they wrote? In genetics normally one gets a copy (allele) of a gene (or actually a chromosome) from each parent. If the alleles differ between parents, for example by a SNP, one would have one copy of each allele. With (NGS) sequencing you would get an even amount of reads for both copies. However with somatic mutations, hence mutations which occur after meiosis and gamete forming, one can lose or gain parts of the chromosome (copy number variation). In this situation, some genomic regions might be deleted or amplified. So the allele of one parent can be deleted, leaving you with only the allele of the other parent.
As requested, I have made a simple drawing of a situation where a region differs between parent alleles with SNPs. After a deletion of one of the allele only reads of the other allele are left.
The following is multiple choice question (with options) to answer.
The chromosomes that have a mixture of maternal and paternal sequence are called what? | [
"gene",
"DNA",
"antibodies",
"recombinant"
] | D | Figure 7.3 In this illustration of the effects of crossing over, the blue chromosome came from the individual’s father and the red chromosome came from the individual’s mother. Crossover occurs between non-sister chromatids of homologous chromosomes. The result is an exchange of genetic material between homologous chromosomes. The chromosomes that have a mixture of maternal and paternal sequence are called recombinant and the chromosomes that are completely paternal or maternal are called non-recombinant. |
SciQ | SciQ-5395 | heating-systems
Comparison between the two.
So you can see that, while you use more efficiently the primary energy with the steam boiler, if the electricity you get is from a renewable source then the ceramic might be more environmentally friendly.
Of course, I avoid going into the discussion about carbon emissions, or the total impact on the environment (e.g. consider if your electricity came from nuclear). That makes the problem even more complex.
A Better solution
If you live in a relatively warm climate (i.e. you don't get temperatures under 0 more that a few days per year), a better alternative for electrical power can be a heat pump.
The difference with heat pumps, is that they don't use the electrical energy directly for heating. (Simply put) What they do is they use the electrical energy to mechanically move an arrangement of pumps/compressors/condensors to pump heat energy from one side of the wall to the other. Heat energy that would not usually be inclined to flow towards that direction. More specifically, they take heat from the colder environment and pump it inside a warmer room.
That process, in ideal conditions, is very efficient. For example, for one unit of electrical energy you can nowadays move up to 4 units of heat energy. That ratio of useful energy to energy expended is the basic formula for the famous COP - Coefficient of performance. In this specific example COP would be 4.
So in ideal conditions, if you used 100 units of fossil fuel, and got 35 units of electrical energy, in theory you could get 140 units of heat energy pumped in your room.
Of course, there are limitations. E.g. at cold climates using a heat pump would create ice/frost on the heat pump, which ultimately would lower significantly the COP.
The following is multiple choice question (with options) to answer.
Different types of home heating systems all function by producing what type of energy? | [
"distinct",
"natural",
"electron",
"thermal"
] | D | Types of home heating systems include hot-water, warm-air, and solar heating systems. All of them have the same basic function: producing thermal energy and transferring it to air throughout the house. |
SciQ | SciQ-5396 | food, nutrition, energy-metabolism
Title: What are the bare minimum nutrients required to survive as a human? I am trying to determine the bare minimum nutritional requirements to survive as a human, ignoring energy (caloric) requirements. Another way to ask this question is: What elements can humans not live without? I am not inquiring solely about what nutrients are needed, but also their approximate amounts.
Imagine pills that a person can take that covers all their base nutritional needs and that after taking this pill the person can eat whatever they want to meet their caloric requirements. Hypothetically, this pill could have some amount (how much?) fat, carbohydrates, protein, fiber, minerals, and vitamins, and the person could subsequently eat any other food to meet their caloric requirements knowing their nutritional needs would already be otherwise met. Lets ignore the possibility of the person suffering from health issues due to eating too much of any specific food to meet their caloric requirements (e.g., taking the magic pills and then eating only butter).
A person in this situation could think "Ok I've got most of my bases covered, now I just need to ingest another 1000 calories of (almost) anything I want).
What nutrients are absolutely necessary for humans to survive indefinitely, and how much of these nutrients are required?
I am hoping for a complete list with approximate amounts (e.g., 20g fat, 20g carbohydrates, 1mg Vitamin X, .05mg Vitamin Y, 10mg mineral X). Essential nutrients include (NutrientsReview):
Water
9 amino acids: histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, tryptophan, threonine, valine
2 fatty acids (alpha linolenic and linoleic acid)
Vitamins: A, B1, B2, B3, B5, B6, folic acid, biotin, B12, C,
D, E and K (and choline, which is considered a vitamin-like substance)
Minerals: calcium, chromium, chloride, copper, iodine, iron,
manganese, molybdenum, phosphorus, potassium, selenium, sodium, zinc
The following is multiple choice question (with options) to answer.
Nutrients the body needs in relatively large amounts are called what? | [
"macronutrients",
"minerals",
"micronutrients",
"vitamins"
] | A | Nutrients the body needs in relatively large amounts are called macronutrients . They include carbohydrates, proteins, lipids, and water. All macronutrients except water can be used by the body for energy. (The energy in food is measured in a unit called a Calorie. ) The exact amount of each macronutrient that an individual needs depends on many factors, including gender and age. Recommended daily intakes by teens of three macronutrients are shown in Table below . Based on your gender and age, how many grams of proteins should you eat each day?. |
SciQ | SciQ-5397 | particle-physics
Title: Explanation for self-rupture glass is needed I witnessed a phenomenon that I couldn't conclude its cause. Please bear with me for the length of the recall, for I merely want to include any details that might help us to investigate. I had a cooking glass lid sat on a wooden shelf that is away from the stove and oven and other heating objects. The shelf is nailed on the wall and is situated just above my eye level, and a counter top is also on the same side of the wall where the shelf is installed.
Now here comes the surprise. In a winter afternoon 2011, my room had almost the same temperature as an autumn morning, and while I was cutting my lettuce on that counter top which I pointed out in above passage, a pounding sound, as if a heavy car door slam or a tree trump falling on top of the roof, knocked its introduction from the shelf that was just above my eye level. First, I thought I may had knocked something around me off(which I didn't believe that for there wasn't anything around me to knock off); then I thought it may be my neighbor next door dropping a heavy box; last, I suspected somewhere my roof top collapsed.
But it was my third suspicion directed me to meet that glass lid I mentioned above, and I found it had ruptured completely like glacier creaked BUT still having all broken pieces bounded without any pieces scattering toward random direction! Only the nob of the lid popped out partially. Before this happened, I hadn't used that lid for cooking for years, and I didn't removed it from any heating object nor there was something on top of the lid that day, and I believe what the lid had maybe just an invisible layer of dust.
I was glad my face hadn't been stung by any glass residues, but ponder what really happen to that glass lid and why it ruptured without collapsed. Below, I attached 2 pictures of the scene from that day. If you have any similar experience or know the theory behind it, may you please drop me an explanation to this incidence? Thank you in advance.
The following is multiple choice question (with options) to answer.
Which property changes when a glass breaks? | [
"its physical property",
"Chemical",
"State",
"density"
] | A | When glass breaks, its physical properties change. Instead of one solid sheet of glass, it now has holes and cracks. |
SciQ | SciQ-5398 | antigen
Title: Minimum size for a peptide/protein to be immunogenic in human? What is the minimum size for an (injected) peptide/protein to cause immunogenic response in human?
A reference is very helpful, as well.
Thanks in advance There's a few limiting factors including how proteins are presented that constrains the actual size needed to get peptide presentation. These depend largely on the MHC molecules (HLA in humans). The binding groove in MHC-I actually limits the size of peptides it can load to 8-10 amino acids, 9 being the most common. This is because "pockets" at either end of the binding groove are said to actually grasp the peptide, and it doesn't allow for much longer sequences. MHC-II lacks these grasping pockets, and so it can bind much longer sequences (Figure 1). MHC-II typically binds sequences of 13-25 amino acids.
Figure 1. Difference between the MHC-I and II binding groove.
There are also a given number of requisite anchor residues that complement the binding pocket of the MHC binding groove that mostly display a particular character at the given position (normally polar at a given position, etc.) (Figure 2).
Figure 2. Just a sampling of possibilities across HLA isoforms.
All information and figures courtesy of Parham "The Immune System," 4th ED.
If the presented peptide has met the prerequisities and has been identified by a leukocyte, in theory it should produce an immune response. I think these are some good considerations to make when you're thinking about how small can a peptide be. I'm assuming here that MHC-II would be handling your injected protein through an extracellular pathway (I can't know for sure), and so the smallest literature MHC-II peptide range I've ever seen is 11 amino acids on the low side. There are a number of computational studies out there that attempt to predict MHC affinity, but it's problematic due to the range of sizes MHC-II may bind and there is variability among the binding cores that contain the anchor amino acids.
The following is multiple choice question (with options) to answer.
What do you call large, y-shaped proteins that recognize and bind to antigens? | [
"proteins",
"antibodies",
"parasites",
"membranes"
] | B | Plasma cells are activated B cells that secrete antibodies. Antibodies are large, Y-shaped proteins that recognize and bind to antigens. Plasma cells are like antibody factories, producing many copies of a single type of antibody. The antibodies travel throughout the body in blood and lymph. Each antibody binds to just one kind of antigen. When it does, it forms an antigen-antibody complex (see Figure below ). The complex flags the antigen-bearing cell for destruction by phagocytosis . |
SciQ | SciQ-5399 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
What is the process by which plants make their own food? | [
"glycolysis",
"cellular respiration",
"photosynthesis",
"metabolism"
] | C | |
SciQ | SciQ-5400 | zoology
Title: Why Egg shell is not called a cell wall? Egg is a single cell and has a outer hard covering outside inside which there is a cell membrane. Then why isn't the egg shell a cell wall?
Is it because no exchange of materials take place through it? Egg shells are actually porous so that the organism inside can aquire oxygen and get rid of carbon dioxide as it develops (http://www.scientificamerican.com/article/bring-science-home-chick-breathe-inside-shell/).
Although gametes (eggs and sperm) are single cells, an egg shell (or "wall" if you like) is created by the mother (therefore external to the egg cell) and contains many compartments separated by protein membranes:
https://www.exploratorium.edu/cooking/eggs/eggcomposition.html
The initial egg cell is a tiny fraction of a size of the egg visualised here, so it would therefore be incorrect to call the egg shell a "cell wall" as it is a structure independent of the egg cell itself.
The following is multiple choice question (with options) to answer.
In amniotes that lay eggs, the shell of the egg provides protection for the developing embryo while being permeable enough to allow for the exchange of carbon dioxide and this? | [
"oxygen",
"tissue",
"Protein",
"gas"
] | A | Characteristics of Amniotes The amniotic egg is the key characteristic of amniotes. In amniotes that lay eggs, the shell of the egg provides protection for the developing embryo while being permeable enough to allow for the exchange of carbon dioxide and oxygen. The albumin, or egg white, provides the embryo with water and protein, whereas the fattier egg yolk is the energy supply for the embryo, as is the case with the eggs of many other animals, such as amphibians. However, the eggs of amniotes contain three additional extra-embryonic membranes: the chorion, amnion, and allantois (Figure 29.20). Extra-embryonic membranes are membranes present in amniotic eggs that are not a part of the body of the developing embryo. While the inner amniotic membrane surrounds the embryo itself, the chorion surrounds the embryo and yolk sac. The chorion facilitates exchange of oxygen and carbon dioxide between the embryo and the egg’s external environment. The amnion protects the embryo from mechanical shock and supports hydration. The allantois stores nitrogenous wastes produced by the embryo and also facilitates respiration. In mammals, membranes that are homologous to the extra-embryonic membranes in eggs are present in the placenta. |
SciQ | SciQ-5401 | 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 term is used to describe viruses that live in a dormant state inside the body? | [
"latency",
"dorment",
"potential",
"hidden"
] | A | Some viruses live in a dormant state inside the body. This is called latency . For example, the virus that causes chicken pox may infect a young child and cause the short-term disease chicken pox. Then the virus may remain latent in nerve cells within the body for decades. The virus may re-emerge later in life as the disease called shingles. In shingles, the virus causes painful skin rashes with blisters (see Figure below ). |
SciQ | SciQ-5402 | botany
All
142
45.01± 5.23
2306
45.64± 4.95
18 124
46.85± 3.98
3754
47.88± 3.49
For an algal estimate, see here:
Carbon is obtained from the post-carbon-capture flow and compressed to 1 MPa for transport and supply to the growth volume (requiring 248 kJ/kg of gas). Carbon uptake efficiency is 79%. The algal biomass productivity is 82.5 t/ha-yr (23.8 g/m2-d) with an elemental composition consisting of 48% carbon, 6.3% nitrogen, and 0.6% phosphorus (Huntley et al., 2015).
The following is multiple choice question (with options) to answer.
What is the main component of phytoplankton? | [
"seawater",
"coral",
"sponge",
"algae"
] | D | Algae play significant roles as producers in aquatic ecosystems. Microscopic forms live suspended in the water column. They are the main component of phytoplankton . As such, they contribute to the food base of most marine ecosystems. |
SciQ | SciQ-5403 | 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.
Compounds that contain mainly the elements carbon and hydrogen are called what kind of compounds? | [
"organic compounds",
"natural compounds",
"reactive compounds",
"microscopic compounds"
] | A | Compounds that contain mainly the elements carbon and hydrogen are called organic compounds . This is because they are found mainly in living organisms. Most organic compounds are held together by covalent bonds. An example of an organic compound is glucose (C 6 H 12 O 6 ), which is shown in Figure below . Glucose is a simple sugar that living cells use for energy. All other compounds are called inorganic compounds. Water is an example of an inorganic compound. |
SciQ | SciQ-5404 | human-biology, reproduction
Title: What are possible health risks to women having large numbers of children? What is the possible health issue the women would face in this record?
The record for most children born to a single couple belongs to the
first wife of Feodor Vassilyev of Russia. In 27 pregnancies between
1725 and 1765 she gave birth to 16 pairs of twins, 7 sets of triplets,
and 4 sets of quadruplets for a grand total of 69 children. A common problem for any woman who has experienced pregnancy and childbirth is damage to the levator ani muscle, which comprises a portion of the "pelvic floor."
from here
This can cause a number of symptoms, including urinary incontinence (due to an increase in pressure on the bladder from less effective muscular support), and possible prolapse of the bladder, uterus, or rectum into the vagina, again due to the weakening of the pelvic floor.
The following is multiple choice question (with options) to answer.
What type of diagnosis happens before a baby is born? | [
"maternal",
"postnatal",
"fetal",
"prenatal"
] | D | Prenatal diagnosis refers to the diagnosis of a disease or condition before the baby is born. |
SciQ | SciQ-5405 | nuclear-physics, radioactivity
In particular, a fission to fragments with $2<Z<30$ is almost impossible because those have a relatively low binding energy per nucleon. If one can energetically win by fusion, it's pretty much guarantee that one may also find an energetically favored alpha decay because the alpha particle has a pretty high binding energy per nucleon, allowing the other decay product to have a similar binding energy per nucleon if not lower, thus making the decay more likely.
The opposite implication obviously doesn't hold: most of the known radioactive isotopes are the light ones that can't split by fission (alpha decay is not counted even though it is a sort of "minifission"). In general, alpha and beta radioactivity is much more common among the known nuclides than fission.
It's important to realize that the link between fissiles and radioactivity is a bit indirect: the main isotopes that bring radioactivity to spinach etc. and that represent a public health concern are not the heavy nuclei themselves: it's the decay products such as the isotopes of iodine, cesium, strontium etc. Sometimes they're products of long chains of radioactive decay; the fission of the heavy nuclei is just the beginning of the chain, a tip of an iceberg.
The following is multiple choice question (with options) to answer.
Unlike nuclear fission, which involves dangerous radioisotopes, nuclear fusion involves what two harmless elements? | [
"hydrogen and carbon",
"hydrogen and helium",
"magnesium and helium",
"hydrogen and oxygen"
] | B | The use of nuclear fusion for energy has several pros. Unlike nuclear fission, which involves dangerous radioisotopes, nuclear fusion involves hydrogen and helium. These elements are harmless. Hydrogen is also very plentiful. There is a huge amount of hydrogen in ocean water. The hydrogen in just a gallon of water could produce as much energy by nuclear fusion as burning 1,140 liters (300 gallons) of gasoline! The hydrogen in the oceans would generate enough energy to supply all the world’s people for a very long time. |
SciQ | SciQ-5406 | atmosphere, ocean, hydrology, climate-change
Comment: I strongly endorse the use of wind and hydropower as sources of energy over the further use of fossil fuels. However, I still think it is important to do research into the actual renewability of presumed-renewable energy sources, as we don't want to end up with another fossil fuel-type situation, in which we become aware of dependency on these energy sources and their malignant environmental side-effects long after widespread enthusiastic adoption. Electricity from waves, from hydro (both run-of-river and storage) and from wind, are all indirect forms of solar power. Electricity from tides is different, and we can deal with that in a separate question. Global tidal electricity generation is not yet at the scale of gigawatts, so it's tiny for now.
Winds come about from the sun heating different parts of the planet at different rates, due to insolation angles, varying cloud cover, varying surface reflectivity, and varying specific heat of surface materials. Temperature differentials create wind currents.
Waves come about from wind, so they're a twice-indirect form of solar power.
Sunlight on water speeds up evaporation, lifting the water vapour into clouds, giving them lots of gravitational potential. That rain then falls, sometimes onto high land, from where it can be gathered into storage reservoirs that are tapped for electricity, or where it flows into rivers that are then harnessed in run-of-river hydro.
How much power is there? Well, the insolation from the sun is, at the outer boundary of the Earth's atmosphere, at an intensity of about 1400 Watts per square metre. The Earth's albedo is roughly about 30% - i.e. on average about 400 Watts are reflected back into space, giving an average irradiation into the Earth of about 1000 Watts per square metre. Picture the Earth's surface as seen from the Sun: wherever the Earth is in its orbit on its own axis, and around the Sun, the Sun sees a disc that has the Earth's diameter, so the surface area exposed to the Sun is just $\pi$ times the square of Earth's radius, which is about 6 300 kilometres.
So the incoming solar radiation is $1000 \times 6,300,000^2 \times \pi \approx 125 \times 10^{15} \rm \ W$
The following is multiple choice question (with options) to answer.
What is another environmental benefit of conserving resources? | [
"warmer temperatures",
"more jobs",
"lower prices",
"less trash"
] | D | When we conserve resources, we also cut down on the trash we produce. Americans throw out 340 million tons of trash each year. We throw out 2.5 million plastic bottles alone—every hour! Most of what we throw out ends up in landfills ( Figure below ). In a landfill, all those plastic bottles take hundreds of years to break down. What are the problems caused by producing so much trash? Natural resources must be used to produce the materials. Land must be given over to dump the materials. If the materials are toxic, they may cause pollution. |
SciQ | SciQ-5407 | physiology, herpetology, poison, amphibians
+
0.002 mg/L will fatally damage the sensitive skin on tadpoles, frogs, salamanders and other amphibians.
another source:
Free chlorine (Cl2) is a greenish gas that is well known for its
highly toxic properties as can be attested to by the thousands of
soldiers that died and were severely injured from chlorine exposure
during World War I. In water, chlorine is the most toxic substance
that we will discuss. Ironically for the amphibian keeper, it is this
toxic nature of chlorine and its ability to denature proteins, which
makes its encounter inevitable. Chlorine is generally used as an
antibacterial agent in municipal water supplies and may be present in
concentrations of over 9 mg/1 in some tap water (measured in Houston,
Texas as an example, although levels were generally lower). The
concentration of chlorine in municipal water supplies can vary greatly
from day to day, or even hour to hour, depending on conditions at the
water treatment facilities. Concentrations as low as 0.0034 mg/1 have
been noted to reduce reproduction in fathead minnows with 72 hour
LC100 (lethal concentration for 100% kill) at 0.15 mg/1 (Arthur and
Eaton,1971). LC50 (96 hour) for the shiners (Notemigonus chrysoleucas)
was as low as 0.19 mg/1 (Esvelt et al., 1971). The concentrations
found in municipal water supplies are many times greater than the
minimum lethal concentrations for many aquatic life forms.
Thus, the well being of the frog in the water of the swimming pool depends on the time the frog spends in the water. Eventually, with extended exposure the chlorine concentration will exceed the one compatible will life and the frog will die. This time is multifactorial variable, thus cannot be assessed easily - the weight and the skin surface area and skin permeability will affect the frog survival in a great degree.
The following is multiple choice question (with options) to answer.
The bright color of poison dart frogs serves what purpose? | [
"attracting mates",
"warning predators",
"attracting predators",
"no purpose"
] | B | Poison dart frogs have toxins in their skin. Their bright colors warn potential predators not to take a bite!. |
SciQ | SciQ-5408 | dna, terminology
Title: Is a DNA molecule a single strand of polynucleotide or two of them linked together? Our molecular biology teacher told us that a double helix of DNA was composed of two DNA molecules linked together by hydrogen bonds. The thing is, until now, I always thought a DNA molecule was composed of two strands, those being polynucleotides, both of them being linked together. I can't find a link which is saying the same as my teacher, even if it seems technically correct to call a double helix a dimer of two DNA molecules.
I was curious to know what was the exact terminology. As you pointed out, though this may be basic biology, seeking clarification when receiving conflicting information is a good thing. Don't feel embarrassed for asking. :)
.. our molecular biology teacher told us that a double helix of DNA was composed of two DNA molecules linked together by hydrogen bonds.
Respectfully, your teacher is incorrect. A single, double-stranded DNA molecule is comprised of two helical shaped polynucleotides, and are connected together via hydrogen bonding.
Highlight of each polynucleotide
Highlight of hydrogen bonding
And just for further validation, according to Molecular Biology of the Cell, 4th ed., by Alberts B, Johnson A, Lewis J, et al.:
A DNA molecule consists of two long polynucleotide chains composed of four types of nucleotide subunits. Each of these chains is known as a DNA chain, or a DNA strand. Hydrogen bonds between the base portions of the nucleotides hold the two chains together.
So, it would seem that your teacher is referring to each polynucleotide, a.k.a. DNA strand, as a DNA molecule. Instead, she should use the verbiage: a single DNA molecule is composed of two DNA strands, which are helical-shaped polynucleotides.
The following is multiple choice question (with options) to answer.
What consist of chains of small molecules called nucleotides? | [
"Atomic acids",
"nucleic acids",
"nitrous acids",
"structural acids"
] | B | Nucleic acids are biochemical compounds that include RNA (ribonucleic acid) and DNA (deoxyribonucleic acid). Nucleic acids consist of chains of small molecules called nucleotides. Nucleotides are the monomers of nucleic acids. A nucleotide is shown in Figure below . |
SciQ | SciQ-5409 | pressure, home-experiment, atmospheric-science
Title: Atmospheric pressure experiment using a cup with a fluid to hold a glass plate When I was in high school, my teacher did an experiment to show the power of atmospheric pressure.
Experiment:
Prepare a glass bottle, fill with water, put a glass plate on the bottle, make sure there is no air in the bottle, just water. Hold the glass bottle and plate, and invert them. Slowly, release the hand which hold the plate. Because the atmospheric pressure, the glass plate will not fall down.
The following is multiple choice question (with options) to answer.
Atmospheric pressure can be measured with what tool? | [
"barometer",
"thermometer",
"scale",
"ruler"
] | A | Atmospheric pressure can be measured with a barometer. |
SciQ | SciQ-5410 | electrons, charge, quasiparticles, leptons
Title: How do electrons get a charge? Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged?
The negative or positive charges were assigned by convention. But it is a fact that electrons are charged. My question is why electrons? and not neutrons?
Also while reading http://en.wikipedia.org/wiki/Electron, I saw that "Independent electrons moving in vacuum are termed free electrons. Electrons in metals also behave as if they were free. In reality the particles that are commonly termed electrons in metals and other solids are quasi electrons, quasiparticles, which have the same electrical charge, spin and magnetic moment as real electrons but may have a different mass ( or Effective mass - extra mass that a particle seems to have while interacting with some force )."
What does this mean? Your question touches the question of ontology in particle physics. Historically we are used to be thinking of particles as tiny independent entities that behave according to some laws of motion. This stems from the atomistic theory of matter, which was developed some two thousand years ago from the starting point of what would happen if we could split matter in ever smaller parts. The old Greeks came to the conclusion that there had to be a limit to that splitting, hence the atom hypothesis was born.
This was just a philosophical idea, of course, until around the beginning of the 19th century we learned to do chemistry so well that it became obvious that the smallest chunks that matter can be split into seemed to be the atoms of the periodic table. A hundred years later we realized that atoms can be split even further into nuclei and electrons. What didn't change was this idea that each chunk had its own independent existence.
This idea ran into a deep crisis during the early 20th century when we discovered the first effects of quantum mechanics. It turns out that atoms and nuclei and electrons do not, at all, behave like really small pieces of ordinary matter. Instead, they are behaving radically different, so different, indeed, that the human imagination has a hard time keeping up with their dynamic properties.
The following is multiple choice question (with options) to answer.
What kind of charge do electrons have? | [
"positive",
"negative",
"unusual",
"effective"
] | B | electrons, which have a negative electric charge. |
SciQ | SciQ-5411 | toxicology
Liver damage in animals exposed to white phosphorus progresses
rapidly. Four hours after receiving a single oral dose of white
phosphorus, minimal fatty changes in hepatocytes were observed; by 12
hours fatty changes were extensive (Ghoshal et al. 1969). Exposure to
white phosphorus has been shown to damage the rough endoplasmic
reticulum and cause a disaggregation of polyribosomes (Ganote and Otis
1969; Pam et al. 1972). This damage results in impairment of protein
synthesis, in particular, a decrease in the synthesis of the
apolipoprotein portion of very low density lipoproteins (VLDL), which
are required for the transport of triglycerides. A significant
decrease in protein synthesis has been detected as early as 3 hours
after oral exposure (Barker et al. 1963). The smooth endoplasmic
reticulum is also involved in the formation of the VLDLs, and damage
to the smooth endoplasmic reticulum also impairs the formation of
VLDLs. The net result of these ultrastructural changes is an
accumulation of triglycerides in the liver (Ghoshal et al. 1969). This
results in steatosis and fibrosis, which is one of the mechanisms
involved in the hepatotoxicity of white phosphorus. The mechanism
behind the damage to the endoplasmic reticulum is not known; also, it
is not known whether white phosphorus itself or a metabolite of white
phosphorus is the damaging agent. In addition to these damages, white
phosphorus or a metabolite causes damage to the mitochondria and
nuclei in the livers of animals orally exposed to white phosphorus
(Ghoshal et al. 1969). The damage to the mitochondria may impair the
cell’s ability to produce ATP, thus resulting in necrosis of the cell.
The following is multiple choice question (with options) to answer.
What are lipids that contain phosphorus called? | [
"phospholipids",
"amino acids",
"eukaryotes",
"alkaloids"
] | A | Some lipids contain the element phosphorus as well as oxygen, carbon, and hydrogen. These lipids are called phospholipids. Two layers of phospholipid molecules make up most of the cell membrane in the cells of living things. |
SciQ | SciQ-5412 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
How many chambers does the stomach of a ruminant have? | [
"4",
"3",
"5",
"1"
] | A | |
SciQ | SciQ-5413 | reaction-mechanism
It is generally said that reactants react so that they can achieve a
lower energy state. Then why does a reversible reaction occur in the
first place?
Good question. Remember that we can always add energy to make an unfavorable reaction proceed. For example, the sodium ion, which is isoelectronic with neon, is stable with a full octet of electrons. However, we can still take away more electrons. It just takes a rather sizable application of energy.
The following is multiple choice question (with options) to answer.
What states that chemical reactions occur when atoms, ions, or molecules collide? | [
"disturbance theory",
"elemental theory",
"reaction theory",
"collision theory"
] | D | Collision theory states that chemical reactions occur when atoms, ions, or molecules collide. In other words, these species need to make contact with one another in order for a reaction to take place. Based on this concept, along with a couple of other key points, collision theory helps to explain why certain factors will influence the rate of a chemical reaction. |
SciQ | SciQ-5414 | 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.
Biological macromolecules are organic, which means that they must contain what? | [
"hydrogen",
"oxygen",
"aluminum",
"carbon"
] | D | 2.3 | Biological Molecules By the end of this section, you will be able to: • Describe the ways in which carbon is critical to life • Explain the impact of slight changes in amino acids on organisms • Describe the four major types of biological molecules • Understand the functions of the four major types of molecules The large molecules necessary for life that are built from smaller organic molecules are called biological macromolecules. There are four major classes of biological macromolecules (carbohydrates, lipids, proteins, and nucleic acids), and each is an important component of the cell and performs a wide array of functions. Combined, these molecules make up the majority of a cell’s mass. Biological macromolecules are organic, meaning that they contain carbon. In addition, they may contain hydrogen, oxygen, nitrogen, phosphorus, sulfur, and additional minor elements. |
SciQ | SciQ-5415 | evolution, human-anatomy, eyes, human-evolution, human-eye
Title: Is the backward positioning of photoreceptors bad design? (Several questions have been asked about this topic but most are quite old and there has been at least one study since then that has attempted to answer this in a new way)
Since photoreceptors are placed at the back of nerve cells in vertebrates, these nerves have to then bundle up before passing to the brain, leading to a blind spot. This video (from a usually reliable channel) from 2:30-4:00 says that its bad design and is just something the initial eyes in vertebrates fixed on, and was too difficult to correct later.
But this report of a study from 2015 says that this arrangement helps vertebrates see colours more easily during daytime, and is not a bad design.
Even if this design does help in seeing colours better, the same effect could have been achieved through other means without having to create a blind spot, no?
Can this be called a bad design or not? Properly speaking, you should not use the word "design" when talking about evolution. All you can describe are more or less fit variations. A variation that is advantageous in one context can be detrimental in another.
That being said, I assume what you are asking is whether the eyes could be better, as if an engineer would design them from scratch. The answer is "probably yes". The backward wiring of the photoreceptors is an issue that the brain has mostly been able to work around, but it is obvious that forward-facing photoreceptors would be easier to work with. There are multiple issues, one is the blindspot as you identified. Another one is the diffraction of the light by the ganglion cells fibers. Part the light is adsorbed too, so because of the non-homogeneous thickness of the macula there are color distortions near the center of the visual field. But again, it is not impossible that having a forward-facing retina would be more detrimental in some environment, although I fail to think of a case where a backward retina would be better.
The following is multiple choice question (with options) to answer.
What do you call the membrane lining the back of the eye? | [
"cornea",
"retina",
"aperture",
"stimulation"
] | B | The retina is a membrane lining the back of the eye. The retina has nerve cells called rods and cones that change images to electrical signals. Rods are good at sensing dim light but can’t distinguish different colors of light. Cones can sense colors but not dim light. There are three different types of cones. Each type senses one of the three primary colors of light (red, green, or blue). |
SciQ | SciQ-5416 | organs, skin, pain, injury
Title: Why Is The Toughness Of Skin Different On Different Parts Of The Body? My cat was licking my arm with his sandpaper like tongue. It hurt and the area he was licking was slightly smarting afterwards. However, when he licks the palm of my hand the feeling is rather ticklish and results in no pain during or after.
We can pick up sharp, prickly, abrasive objects with our hands (palms/fingers) and even rub against them and have little to no damage incurred. However, if we do the same with say the back of our hand we are more likely to be injured.
I thought maybe the skin is thicker in our palms and that is resulting in our palms being more resilient. But, our palms are so sensitive to touch that it makes me think the skin is thinner to allow the nerves closer access to our environment.
Why is there such a stark difference in different areas of skin on our body when it comes to feeling pain and being susceptible to injury from scrapes, bruises, cuts, etc? As dd3 said the density of mechanoreceptors dictates skin sensitivity to touch (also look at penfield map. It is a nice illustration of how different senses are mapped to the brain and to what extent each region is sensitive to stimulus). Skin thickness is also different in different regions. This article says that Dikkopf1 (a Wnt pathway antagonist) controls skin thickness.
The following is multiple choice question (with options) to answer.
Lacking blood vessels, nerve endings, or glands, the epidermis is the outer layer of what? | [
"lungs",
"liver",
"skin",
"brain"
] | C | The epidermis is the outer layer of skin. It consists almost entirely of epithelial cells. There are no blood vessels, nerve endings, or glands in this skin layer. Nonetheless, this layer of skin is very active. It is constantly being renewed. How does this happen?. |
SciQ | SciQ-5417 | endocrinology
Excitement or stress response, including fast heart rate and breathing and anxiety: short term response: adrenaline; long-term response: cortisol
Appetite: ghrelin, leptin, adiponectin, cholecystokinin, insulin, glucagon-like peptide, gastrointestinal peptide...
Sexual drive: sex hormones, mainly testosterone and estradiol
Sleepiness: melatonin, cortisol
Depression: cortisol, sex hormones (mainly in women)
The point of this answer is to show that some of your feelings can be simply affected by hormones, which are note some ultimate forces, and that being aware of that can help you to control them to some extent.
The following is multiple choice question (with options) to answer.
The deepest region of the adrenal cortex is the zona reticularis, which produces small amounts of a class of steroid sex hormones called what? | [
"dioxins",
"androgens",
"estrogen",
"testosterone"
] | B | Hormones of the Zona Reticularis The deepest region of the adrenal cortex is the zona reticularis, which produces small amounts of a class of steroid sex hormones called androgens. During puberty and most of adulthood, androgens are produced in the gonads. The androgens produced in the zona reticularis supplement the gonadal androgens. They are produced in response to ACTH from the anterior pituitary and are converted in the tissues to testosterone or estrogens. In adult women, they may contribute to the sex drive, but their function in adult men is not well understood. In post-menopausal women, as the functions of the ovaries decline, the main source of estrogens becomes the androgens produced by the zona reticularis. |
SciQ | SciQ-5418 | 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.
All living things maintain a stable internal environment through what process? | [
"homeostasis",
"consciousness",
"alertness",
"maintenance"
] | A | All living things have ways of maintaining a stable internal environment. This stable condition is called homeostasis. |
SciQ | SciQ-5419 | ecology
Title: Statement about Tropical Rainforests I made a statement about tropical rainforests, and I want to know if it's somewhat true or not:
The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The reason that a tropical rainforest has a huge amount of vegetation is because of the quick mineralisation. If a dead leaf falls onto the ground, it immediately gets turned into minerals, which the plants immediately use for sustaining theirselves There are many websites which describe this phenomenon. They all seem to confirm the basic premise of the question: in tropical rain forests most of the minerals are held in the biomass and rapid decomposition contributes to the recycling of these nutrients for new growth. One example is here.
Tropical rainforests are noted for the rapid nutrient cycling that occurs on the ground. In the tropics, leaves fall and decompose rapidly. The roots of the trees are on the surface of the soil, and form a thick mat which absorbs the nutrients before they reach the soil (or before the rain can carry them away). The presence of roots on the surface is a common phenomenon in all mature forests; trees that come along later in succession win out in competition for nutrients by placing their roots over top of the competitors, and this pattern is seen in the temperate rainforest as well. What does not occur in the temperate rainforest, however, is a rapid cycling of nutrients. Because of the cold conditions and the acidity released by decomposing coniferous needles on the forest floor, decomposition is much slower. More of the nutrients are found in the soil here than would be the case in a tropical forest, although like the tropical forest most of the nutrients are held in the plants and animals themselves.
I looked for actual evidence of these differences in rates of decomposition and I found this:
Salinas, N. et al. (2011) The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests. New Phytologist 189: 967-977
The following is multiple choice question (with options) to answer.
Tropical rainforests are an example of a climate that occurs near what? | [
"poles",
"equator",
"deserts",
"tundras"
] | B | Tropical wet climates occur at or very near the Equator. They have high rainfall year round. Tropical rainforests ( FIgure below ) grow in this type of climate. |
SciQ | SciQ-5420 | thermodynamics, energy, combustion
Title: What is change in internal energy of a system in which combustion occurs at constant temperature? We got a question in a test, in which we were asked which system has zero change in internal energy and it had an option which was combustion of methane at constant temperature. I imagined this to be a situation in which the combustion is carried out in a system, where the change in internal energy of system due to heat released, is cancelled by the work done by the system. The reason why I thought of this is because of the formula,
∆U=nCv∆T,
But this was wrong. When I asked my sir how this was wrong, he was not able to say why the ans using above stated formula is wrong. He tried giving me a logical explanation in which he said that a small part of the system releases heat which is used by the remaining part for it's combustion, thus the total temperature remains constant. but I am unable to understand why we choose to only study a part of the system while we have the entire system. It makes no sense to me. Could someone please explain how my sir's explanation is valid here and why the formula is wrong to use here? The change in internal energy of a reaction mixture is a function not only of the temperature change but also of the changes in the amounts of reactants and products in the mixture. This is because energy is consumed and released when we break- and make chemical bonds. The equation you wrote for the internal energy change applies only to a pure species or to a mixture of constant chemical composition. The occurrence of chemical reactions causes a change in the internal energy even at constant temperature.
The following is multiple choice question (with options) to answer.
What changes the chemical composition of a substance and can only occur through a chemical reaction? | [
"Oxygen Changes",
"carbon changes",
"mineral changes",
"chemical changes"
] | D | Pure substances, such as compounds, can be separated through chemical changes. Chemical changes change the chemical composition of a substance and can only occur through a chemical reaction. |
SciQ | SciQ-5421 | zoology, ethology
Title: Is there a term for tool use in animals? Is there a technical/scientific term that scientists use to refer to tool making abilities found in certain types of animals?
Reference http://en.wikipedia.org/wiki/Animal_cognition#Tool_and_weapon_use Having read this article on tool use in Chimpanzees in full, I am inclined to say that if such a term existed then either the article itself or the titles of any of the 30 articles referenced would have included it.
Searching a couple of online biological dictionaries and ethology sites hasn't yielded anything either, therefore until someone else points out that I'm missing the obvious I'd say you're free to coin the term yourself!
The following is multiple choice question (with options) to answer.
What term is used to describe the way that animals interact with each other or their environment? | [
"animal magnetism",
"animal behavior",
"animal decline",
"animal range"
] | B | Animal behavior is any way that animals interact with each other or their environment. Many animal behaviors promote fitness by increasing the chances of surviving or reproducing. If such behaviors are controlled by genes, they evolve by natural selection. |
SciQ | SciQ-5422 | entomology, ant
Title: In an ant (or bee) colony, what is the very approximate ratio of new breeders to workers? For example, out of every 1000 eggs laid, X mature into drones and/or virgin queens. That seems impossibly precise but it illustrates the kind of number I want well. I'll accept answers for any species and any number of species, even one, with any amount of precision or lack thereof, because right now I can't even feel confident saying that there are more workers or more breeders, though I obviously suspect more workers.
I would also be ecstatic to have any live count just before the nuptial flight, i.e. for this colony in this study there were X workers, Y drones, and Z virgin queens just before the nuptial flight, or X workers and (Y+Z) breeders, or X% of the colony was breeders, or for this species on average X% are breeders just before the nuptial flight.
Anything. Any one thing and I can accept it as an answer.
I can find any number of studies that talk about the sex ratio between drones and virgin queens, so I know someone is counting. Maybe I'm not reading closely enough, but they always seem to slip away from giving all the numbers I need to figure this out for myself. So.
This answer is specific to the western honeybee, Apis mellifera, as there are massive amounts of data on them; more, possibly, than any other insect species. There has certainly been more data collected about them than any other hymenopteran.
At around the time of the nuptial flight, there may be as many as 60,000 workers in the hive, though likely number is more like 15,000 - 20,000. There will be either one (virgin) or two (one mated, one virgin) queens (the old queen will stay with the hive, if she is alive). There may be as many as 400 drones from the original colony (though usually the number is less, around 150 is typical; 10 - 50 of them will actually mate with the queen), and an equal number may join in the flight drawn from other colonies, especially in commercial beekeeping operations. Somewhere between 1000 - 6000 workers will take part in the nuptial flight with the virgin queen and the drones.
The following is multiple choice question (with options) to answer.
What kind of bees are most adult bees in a hive? | [
"queens",
"drones",
"worker bees",
"larvae"
] | C | Most of the adult bees in a colony are workers. They cooperate to build the hive, collect food, and care for the young. Each worker has a specific task to perform, depending on its age. Young worker bees clean the hive and feed the offspring. Older worker bees build the waxy honeycomb or guard the hive. The oldest worker bees leave the hive to find food. |
SciQ | SciQ-5423 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
In most animals, the circulatory system is used to transport blood through the what? | [
"fur",
"nerves",
"body",
"stratum corneum"
] | C | CHAPTER SUMMARY 40.1 Overview of the Circulatory System In most animals, the circulatory system is used to transport blood through the body. Some primitive animals use diffusion for the exchange of water, nutrients, and gases. However, complex organisms use the circulatory system to carry gases, nutrients, and waste through the body. Circulatory systems may be open (mixed with the interstitial fluid) or closed (separated from the interstitial fluid). Closed circulatory systems are a characteristic of vertebrates; however, there are significant differences in the structure of the heart and the circulation of blood between the different vertebrate groups due to adaptions during evolution and associated differences in anatomy. Fish have a two-chambered heart with unidirectional circulation. Amphibians have a three-chambered heart, which has some mixing of the blood, and they have double circulation. Most non-avian reptiles have a three-chambered heart, but have little mixing of the blood; they have double circulation. Mammals and birds have a four-chambered heart with no mixing of the blood and double circulation. |
SciQ | SciQ-5424 | genetics, botany, seeds
Title: What DNA does a self-fertile plant's seedling have? Some plants are said to be self-fertile. An example is Prunus tomentosa.
Assuming that no cross-pollination happened with other plants, if a self-fertile plant such as prunus tomentosa produces a seedling, what DNA will the seedling have? Is the seedling's DNA an exact copy of the parent plant's DNA, or do the genes get rearranged? Selfing (aka self-fertilizing) differs from cloning. When selfing occurs, the offspring is not an exact copy of the parent. When cloning occurs, the offspring is an exact copy (except for a few mutations) of the parent.
Selfing implies that an individual will produce two gametes (typically a spermatozoid and an ovule but that might be a bit more complicated) and these two gametes are fusing to give the zygote (egg or offspring if you prefer).
As a consequence, when selfing, meiosis is occurring (and therefore segregation and recombination) so that the offspring is not an exact clone of the parent but rather some kind of a rearrangement of the parent genome (with a few mutations of course).
The following is multiple choice question (with options) to answer.
In sexually reproducing organisms, parents pass a copy of each type of what to their offspring by producing gametes? | [
"genome",
"chromosome",
"molecule",
"phenotype"
] | B | In sexually reproducing organisms, parents pass a copy of each type of chromosome to their offspring by producing gametes. When gametes are fertilized and form offspring, each has a unique combination of chromosomes and genes from both parents. The inherited gene combination determines the characteristics of the offspring. |
SciQ | SciQ-5425 | newtonian-mechanics, conservation-laws
So generally the plate will move : it could translate and also rotate. Constraining forces (and torques) would be needed to keep it in place. If it is released it will move.
The following is multiple choice question (with options) to answer.
At transform plate boundaries, two plates move in which directions? | [
"north and south",
"opposite",
"same",
"parallel"
] | B | At transform plate boundaries, two plates move in opposite direction. |
SciQ | SciQ-5426 | voltage
If the power plant were providing DC voltage though, and you couldn't complete a circuit, then a charge buildup would eventually neutralize whatever process the power plant was using to create the voltage difference. The bigger the piece of Earth your voltmeter were connected to, the longer you'd have before this happens, but I have no idea what actual numbers look like.
The following is multiple choice question (with options) to answer.
The voltages generated at a power plant are stepped up by what passive devices, which then reduce voltage to a safe level at the point of use? | [
"batteries",
"transformers",
"transistors",
"capacitors"
] | B | Figure 20.19 Power is distributed over large distances at high voltage to reduce power loss in the transmission lines. The voltages generated at the power plant are stepped up by passive devices called transformers (see Transformers) to 330,000 volts (or more in some places worldwide). At the point of use, the transformers reduce the voltage transmitted for safe residential and commercial use. (Credit: GeorgHH, Wikimedia Commons). |
SciQ | SciQ-5427 | 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 is the term for the dark brown or black coating found on exposed desert rocks, which is formed of iron and manganese oxides? | [
"desert varnish",
"desert shadow",
"desert patina",
"desert rust"
] | A | Exposed rocks in desert areas often develop a dark brown or black coating called desert varnish ( Figure below ). Wind transports clay-sized particles that chemically react with other substances at high temperatures. The coating is formed of iron and manganese oxides. |
SciQ | SciQ-5428 | organic-chemistry, electronic-configuration, transition-metals, reference-request, catalysis
My question is, why $\ce{Pt, Ru, Rh, Pd}$ all being transition metals still show different chemoselectivity in hydrogenation reactions?
1st edit: (After reading ringo's comment I think I should add something more) Well, I first thought that the number of $\ce{d}$ electrons is the cause. But, both $\ce{Pd}$ and $\ce{Pt}$ have same number of $\ce{d}$ electrons. Yet, they show different chemoselectivity. I think the difference is because $\ce{Pt}$ has an $\ce{f}$ orbital filled up.
And, I guess as $\ce{Ru, Rh, Pd}$ belong to same period, they show similar chemoselectivity. Unfortunately, this is extremely complicated and the topic of active research in both computational and inorganic chemistry and chemical engineering. There is no simple answer to your question. We can discuss various forces that go to determining chemoselectivity though.
1) Crystal structure: You said that you are primarily focused on bare metal catalysis, so I will restrict myself to those systems. Not all surfaces of even the same material behave the same. These are commonly described by Miller indices (1), which describe the surface by how a plane cuts through the material's unit cell. The reactivity and selectivity are heavily determined by the exact surface structure (think dangling bond sites, binding sites, multicenter reactivity, all of which are influenced by the surface atomic structure both local and in its immediate environs). Different materials will have different crystal structures based on both electronic effects (like how many valence electrons there are) and size effects (how big atoms are, although there is relatively less variation on this in the 2nd and 3rd rows).
The following is multiple choice question (with options) to answer.
What two ways may catalyst be classified? | [
"reactive or nonreactive",
"homogeneous or heterogeneous",
"fast or slow",
"oxygenated or heterogenous"
] | B | Catalysts may be classified as either homogeneous or heterogeneous. A homogeneous catalyst is uniformly dispersed throughout the reactant mixture to form a solution. Sulfuric acid, for example, is a homogeneous catalyst used in the synthesis of esters such as procaine (Example 13). An ester has a structure similar to that of a carboxylic acid, in which the hydrogen atom attached to oxygen has been replaced by an R group. They are responsible for the fragrances of many fruits, flowers, and perfumes. Other examples of homogeneous catalysts are the enzymes that allow our bodies to function. In contrast, a heterogeneous catalyst is in a different physical state than the reactants. For economic reasons, most industrial processes use heterogeneous catalysts in the form of solids that are added to solutions of the reactants. Because such catalysts often contain expensive precious metals such as platinum or palladium, it makes sense to formulate them as solids that can be easily separated from the liquid or gaseous reactantproduct mixture and recovered. Examples of heterogeneous catalysts are the iron oxides used in the industrial synthesis of ammonia and the catalytic converters found in virtually all modern automobiles, which contain precious metals like palladium and rhodium. Catalysis will be discussed in more detail in Chapter 14 "Chemical Kinetics" when we discuss reaction rates, but you will encounter the term frequently throughout the text. |
SciQ | SciQ-5429 | evolution, dna, theoretical-biology, genomes, species
Title: Biodiversity is restricted by genome combinatorics? Me and some friends are interested in opinions for the following:
Conjecture
The maximum number of species must be limited by the maximum
combinatorial/permutational space that can be occupied by DNA. Thus if
there is a maximum physical genome size this is what will determine
the maximum number of species that can possibly exist.
Explanation
E.G. say maximum number of DNA base pairs able to fit in a genome was $3$, each base pair can be one of either ${A,G,T,C}$. Then there are $4^3 = 64$ possible combinations of genomes. Extrapolate to genome sizes of $x$ base pairs, then there are $4^x$ combinations.
Questions
Would it be possible to claim that the underlying "blueprint" that codes for living diversity sets the absolute maximum for the total "diversity space"?
**Does it make sense to define the total number of species life can achieve with the simple function:
$S < 4^x$, where X is the maximum genome size measured in DNA base pairs?**
Notable Comments
The following is multiple choice question (with options) to answer.
What phylum has the highest number of species on earth? | [
"cephalopods",
"lichens",
"arthropods",
"lophotrochozoa"
] | C | 15.3 Flatworms, Nematodes, and Arthropods Flatworms are acoelomate, triploblastic animals. They lack circulatory and respiratory systems, and have a rudimentary excretory system. The digestive system is incomplete in most species. There are four traditional classes of flatworms, the largely free-living turbellarians, the ectoparasitic monogeneans, and the endoparasitic trematodes and cestodes. Trematodes have complex life cycles involving a secondary mollusk host and a primary host in which sexual reproduction takes place. Cestodes, or tapeworms, infect the digestive systems of primary vertebrate hosts. Nematodes are pseudocoelomate members of the clade Ecdysozoa. They have a complete digestive system and a pseudocoelomic body cavity. This phylum includes free-living as well as parasitic organisms. They include dioecious and hermaphroditic species. Nematodes have a poorly developed excretory system. Embryonic development is external and proceeds through larval stages separated by molts. Arthropods represent the most successful phylum of animals on Earth, in terms of number of species as well as the number of individuals. They are characterized by a segmented body and jointed appendages. In the basic body plan, a pair of appendages is present per body segment. Within the phylum, classification is based on mouthparts, number of appendages, and modifications of appendages. Arthropods bear a chitinous exoskeleton. Gills, tracheae, and book lungs facilitate respiration. Embryonic development may include multiple larval stages. |
SciQ | SciQ-5430 | waves
Title: Question about the dispersion relation I'm a Non-physics major student. Recently, I am puzzling by the dispersion relation.
For a wave, we have $v=f\lambda$, where $v$, $f$ and $\lambda$ is the velocity, frequency and wave length of the wave, respectively. According to this relation, velocity should depends on the frequency. Then why should we have the definition of dispersive medium, as in my opinion everything is dispersive. Because from the formula above, the velocity should automatically depends on the frequency. Can anybody help me with my question? Thanks a lot! For media where the speed does not depend on frequency, the equation $v = f \lambda$ does not mean $v$ depends on the frequency. It is a relationship between $f$ and $\lambda$ such that when you multiply them together they give the speed $v$.
For a non-dispersive medium if you know the frequency of the wave and its wavelength, then you can work out the speed and this number is the same for all frequencies and wavelengths.
This means that if you change the frequency of the wave then (since you also know the speed $v$ as a fixed number) you can work out the wavelength (similarly if you have a wave with a different wavelength you can determine the frequency).
For media described as dispersive then you write this as $v(f)$. This means if you know the wavelength for one particular frequency you can calculate the speed of the wave for that combination.
But, if the frequency changes and you do not know how the speed depends on frequency, then you cannot work out the wavelength for a different frequency (since you do not know what the speed is, as it changes with frequency and you have only worked it out for one frequency).
The following is multiple choice question (with options) to answer.
The speed of a wave is a product of its wavelength and what else? | [
"density",
"magnitude",
"voltage",
"frequency"
] | D | The speed of a wave is a product of its wavelength and frequency. Because the speed of electromagnetic waves through space is constant, the wavelength or frequency of an electromagnetic wave can be calculated if the other value is known. |
SciQ | SciQ-5431 | astrophysics, stars, plasma-physics
Title: Plasma and Stars I have read that most stars are made mostly of plasma.
My questions in this statement are:
Are there stars not made of plasma?
In what percentage stars are made of plasma?
Are there stars not made of plasma?
.....
Plasma is an electrically neutral medium of unbound positive and negative particles (i.e. the overall charge of a plasma is roughly zero). It is important to note that although the particles are unbound, they are not ‘free’ in the sense of not experiencing forces. When a charged particle moves, it generates an electric current with magnetic fields; in plasma, the movement of a charged particle affects and is affected by the general field created by the movement of other charges.
For more details see this link too.
A basic effect of the motion of charges is that electromagnetic radiation is created, i.e. light and thus stars certainly have plasma because they are called stars for being stationary sources of light in the night sky, in contrast to planets. The sun in the center of the solar system is a star and allows us to study the composition of stars, including the evident plasma.
......
Our Sun, and all of the other stars, are made of plasma, much of interstellar space is filled with a plasma, albeit a very sparse one, and intergalactic space too.
[note that "all other stars is not really correct in this wiki link. see below]
Stars that are not wholy plasma are neutron stars:
A neutron star is the collapsed core of a large (10–29 solar masses) star. Neutron stars are the smallest and densest stars known to exist.1 With a radius on the order of 10 km, they can, however, have a mass of about twice that of the Sun. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past the white dwarf star density to that of atomic nuclei.
....
Neutron stars that can be observed are very hot and typically have a surface temperature around 6×10^5 K.
The following is multiple choice question (with options) to answer.
What type of gas are stars made up of? | [
"calcium",
"hydrogen",
"water vapor",
"freon"
] | B | the fact that stars are made up of very lightweight hydrogen gas. |
SciQ | SciQ-5432 | 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.
What are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules? | [
"cells",
"proteins",
"carbons",
"acids"
] | B | Proteins Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective; they may serve in transport, storage, or membranes; or they may be toxins or enzymes. Each cell in a living system may contain thousands of different proteins, each with a unique function. Their structures, like their functions, vary greatly. They are all, however, polymers of amino acids, arranged in a linear sequence. The functions of proteins are very diverse because there are 20 different chemically distinct amino acids that form long chains, and the amino acids can be in any order. For example, proteins can function as enzymes or hormones. Enzymes, which are produced by living cells, are catalysts in biochemical reactions (like digestion) and are usually proteins. Each enzyme is specific for the substrate (a reactant that binds to an enzyme) upon which it acts. Enzymes can function to break molecular bonds, to rearrange bonds, or to form new bonds. An example of an enzyme is salivary amylase, which breaks down amylose, a component of starch. Hormones are chemical signaling molecules, usually proteins or steroids, secreted by an endocrine gland or group of endocrine cells that act to control or regulate specific physiological processes, including growth, development, metabolism, and reproduction. For example, insulin is a protein hormone that maintains blood glucose levels. Proteins have different shapes and molecular weights; some proteins are globular in shape whereas others are fibrous in nature. For example, hemoglobin is a globular protein, but collagen, found in our skin, is a fibrous protein. Protein shape is critical to its function. Changes in temperature, pH, and exposure to chemicals may lead to permanent changes in the shape. |
SciQ | SciQ-5433 | electromagnetism, magnetic-fields, history
Title: What this thing is and what it's used for? Images:
I'm not sure if this is the right stackexchange to ask this question but i haven't found a "gas display detection and measuring devices" stackexchange so physics seems like a somewhat reasonable place to ask.
I've found something looking like a chandelier i'm supposed to sell online on my job and i have no idea what it is used for, all i can gather is that there are three compasses that function and that can be locked in place with a small lever. the outside of the wooden box says:
"Hermann Sewerin
Vorm. Vulkan-Werk GMBH
Gaspatex(R)
Gütersloh i. Wf.
Gas-Anzeige-Spür- und Messgeräte"
Meaning gas display detection and measuring devices from a german manufacturer of such devices.
Thanks for any help, or for pointing me in the right direction to ask. that thing indicates the magnetic field strength emanating from a tube carrying a current of electricity through the hole in the center of the device. it is an antique and hasn't been used for this purpose for probably 75 years.
The following is multiple choice question (with options) to answer.
A geiger counter is used for detecting what? | [
"pressure",
"radiation",
"convection",
"mutation"
] | B | One of the simplest ways of detecting radioactivity is by using a piece of photographic film embedded in a badge or a pen. On a regular basis, the film is developed and checked for exposure. Comparing the exposure level of the film with a set of standard exposures indicates the amount of radiation a person was exposed to. Another means of detecting radioactivity is an electrical device called a Geiger counter (Figure 15.2 "Detecting Radioactivity"). It contains a gas-filled chamber with a thin membrane on one end that allows radiation emitted from radioactive nuclei to enter the chamber and knock electrons off atoms of gas (usually argon). The presence of electrons and positively charged ions causes a small current, which is detected by the Geiger counter and converted to a signal on a meter or, commonly, an audio circuit to produce an audible “click. |
SciQ | SciQ-5434 | evolution, species
Title: Reasons why living fossils exist?
A living fossil is a living species (or clade) that
appears to be similar to another species otherwise known only from fossils,
typically with no close living relatives.
A living fossil is considered as a successful organism, which has made its way through many major extinction events. Also, the morphology of living fossils resemble some species of organisms which we know only through their fossil remains.
What is the reason for a particular type of species to become a living fossil; is the engineering of this particular species extraordinary, in that it can survive any selection process encountered thus far?
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Have these organisms modified themselves, so that currently their morphology seems to be similar to a fossil organism? One part of your question betrays a serious error:
Is there not enough selection pressure exerted on this species in order to force it to change morphologically?
Actually the reverse is true; constancy of form can only be maintained in the presence of continuous selective pressure. It's just that this is stabilising selection that acts to maintain the existing form rather than push the organism to new morphologies. In fact, most selection acts in this manner. This shouldn't surprise you: organisms are typically well adapted to their environments so changes are more likely to reduce fitness than increase fitness.
It's also worth noting that although living fossils show little morphological change they can continue to show change at the molecular level at rates as high as, or higher than, other organisms - e.g. (May et al 2007; Cao et al 2013).
The following is multiple choice question (with options) to answer.
All species have evolved a pattern of living, called a life history strategy, in which they partition energy for growth, maintenance, and what? | [
"abundance",
"variation",
"deatn",
"reproduction"
] | D | 45.2 Life Histories and Natural Selection All species have evolved a pattern of living, called a life history strategy, in which they partition energy for growth, maintenance, and reproduction. These patterns evolve through natural selection; they allow species to adapt to their environment to obtain the resources they need to successfully reproduce. There is an inverse relationship between fecundity and parental care. A species may reproduce early in life to ensure surviving to a reproductive age or reproduce later in life to become larger and healthier and better able to give parental care. A species may reproduce once (semelparity) or many times (iteroparity) in its life. |
SciQ | SciQ-5435 | species-identification, botany
Title: Identification of a plant Please help me to identify this plant
The plants can be found on italian balconies and I would like to buy one, but I do not know what I should look for.
The habit of the plant is trailing. This is likely to be a stone plant (Aizoaceae), depending on habit, it could well be the ice plant (Carpobrotus edulis). Stone plants are a quite diverse family of succulents from southern Africa, but are widespread throughout the western world as stabilizers of sand-dunes and in gardens as they are very tolerant of lack of watering and high salinity.
Ice plants are very common in the Mediterranean region, having become an invasive pest on much of the coastline.
If it is ice plant, then you can sub-cultivate it by taking a small part of the plant, usually leaves with a bit of stem, but even a leaf by itself may work, and placing it in water or on sandy soil. With regular watering, it should grow roots and then be plantable.
Apparently the leaves of ice plant are edible (hence the edulis part of the name), similar to Aloe I suspect.
The following is multiple choice question (with options) to answer.
What are the most diverse plants on earth? | [
"gymnosperms",
"conifers",
"grasses",
"angiosperms"
] | D | Angiosperms , or flowering plants, are the most abundant and diverse plants on Earth. Angiosperms evolved several reproductive adaptations that have contributed to their success. Like all vascular plants, their life cycle is dominated by the sporophyte generation. A typical angiosperm life cycle is shown in Figure below . |
SciQ | SciQ-5436 | python, pygame, battle-simulation, pokemon
if defender.type2 != None and type_advantage > 0:
for weakness in defender.type2.weakness_list:
if move.type.name == weakness:
if type_advantage == 1:
type_advantage = 2
elif type_advantage == 2:
type_advantage = 4
elif type_advantage == 0.5:
type_advantage = 1
break
for resist in defender.type2.resist_list:
if move.type.name == resist:
if type_advantage == 1:
type_advantage = 0.5
elif type_advantage == 2:
type_advantage = 1
elif type_advantage == 0.5:
type_advantage = 0.25
break
for immune in defender.type2.immune_list:
if move.type.name == immune:
type_advantage = 0
break
return type_advantage
@staticmethod
def get_percent(numerator, denominator):
number = int(round((numerator/denominator)*100))
percent = ("%s%%" % number)
return percent
The following is multiple choice question (with options) to answer.
What is the second line of defense? | [
"inflammatory response",
"immune response",
"rejection of foreign bodies",
"fight or flight"
] | A | The second line of defense includes the inflammatory response and phagocytosis by nonspecific leukocytes. |
SciQ | SciQ-5437 | evolution, biochemistry, plant-physiology, plant-anatomy, life
Title: Plants without bacteria? is it theoretically possible? I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But it is a natural way.
But is it possible to have a world with plants (without mammals or microorganisms and without bacteria) that could exist in the long term. Saying the atmosphere of these world has already enough nitrogen, oxygen and CO2, and of course there is water.
What could break this artificially created world with such conditions (say the world created not from low-level living structures)?
Could bacteria emerge in the world? This is the sort of question that should be considered from more than one perspective. Since this is speculation, take it as a given that there is a lot of 'what if' here.
I doubt most animals and plants can do entirely without bacteria - as you say most of the essential nutrients come from bacteria, who fix nitrogen. If only plants were left on earth, eventually the plants would use up all the nitrogen and they would have to find a way to fix more.
Can bacteria emerge from just a world of plants? I don't think viruses arise spontaneously, but since genomes often have viruses embedded in them, over the course of a billion years or so, its possible since bacteria and viruses continue to be impressed upon our genomes. Would it happen in time? Most would be skeptical whether that timing could work out.
In practice it would be hard to create a world like this. I would be interested to see whether you could sterilize the microorganisms off of seeds without killing the plant for instance. If you're asking about a small sterile environment with only plants, you could do it by adding the nutrients the plants need and giving them sunlight. Such self sustaining systems have been made with cyanobacteria and i'd be surprised if plants could not be included. But these are closed systems and judged by limited amounts of time, so whether this is an answer to your question is not clear. Here it looks like some water plants and fish have been done. If there was a plant that created CO₂ at an adequate rate its possible.
The following is multiple choice question (with options) to answer.
What is the term for when organisms need other organisms to survive? | [
"coexistence",
"intradependence",
"realization",
"interdependence"
] | D | All living things depend on their environment to supply them with what they need, including food, water, and shelter. Their environment consists of physical factors—such as soil, air, and temperature—and also of other organisms. An organism is an individual living thing. Many living things interact with other organisms in their environment. In fact, they may need other organisms in order to survive. This is known as interdependence . For example, living things that cannot make their own food must eat other organisms for food. Other interactions between living things include symbiosis and competition. |
SciQ | SciQ-5438 | organic-chemistry, inorganic-chemistry
But then, some inorganic compounds do have carbon too, and there may even be some compounds that some call organic, and others call inorganic, like $CO_2$.
As I have felt it, in my learnings so far, it's like inorganic chemistry is the default chemistry and organic chemistry goes a step beyond.
But I don't quite grasp the difference.
What is the real semantics behind the word "organic"?
For example, we humans are made of loads of water, and that's a pretty organic thing to me. But then, water is inorganic.
Diamonds are the carbon top of the cake, and do not transmit the idea of being an "organic" thing.
Another very confusing thing are polymers, chanins of loads of carbons with other elements, in many shapes and textures. To me, a piece of "plastic" is not a very organic thing, but indeed, they are!
That brings the semantics into an even more confusing level.
And of course, there must be historical reasons for those chosen words.
Could someone please point out where this distinction comes from and why it is important?
With all my respect to science and the people who made chemistry a useful thing. This question is not about critics, it's about not knowing the facts, so of course I am the ignorant here.
Related and useful: What is the definition of organic compounds? IUPAC is the International Union of Pure and Applied Chemistry, they make recommendations on the nomenclature. IUPAC mentions that the difference between organic and inorganic is not distinct. To quote "The boundaries between ‘organic’ and ‘inorganic’ compounds are blurred." in Brief Guide to the Nomenclature of Inorganic Chemistry R. M. Hartshorn, K.-H. Hellwich, A. Yerin.
Since the terminology of organic vs. inorganic is all human classification, it is not a binary system 0 or 1. What we can say now is that traditionally, all organic compounds do contain carbon. It can come from natural sources or purely synthetic. There is no such restriction. Plastic is an organic compound because it contains a lot of carbon chains.
Note that this word organic, as used in chemistry, has nothing to with the buzz word used in marketing of organic food, organic fruits, organically grown stuff. The word organic comes from French organique designating the jugular vein, hence related to organs or living beings.
The following is multiple choice question (with options) to answer.
What is an organic compound that is made up of only carbon and hydrogen? | [
"an acid",
"a component",
"a hydrocarbon",
"a catalyst"
] | C | A hydrocarbon is an organic compound that is made up of only carbon and hydrogen. A hydrocarbon is the simplest kind of organic molecule and is the basis for all other more complex organic compounds. Hydrocarbons can be divided into two broad categories. Aliphatic hydrocarbons are hydrocarbons that do not contain the benzene group or a benzene ring . Aromatic hydrocarbons contain one or more benzene rings. In this concept, we will discuss the aliphatic hydrocarbons. |
SciQ | SciQ-5439 | biochemistry, physiology, digestive-system, fat-metabolism
Title: How are micelles formed from the byproducts of emulsification in fat digestion? It is known that fat droplets are made into emulsion droplets via the addition of bile salts. It is then said that the emulsion droplets are made into micelles through some sort of lipase, which can be absorbed and transported to different cells through the LDL and HDL pathway.
My question is what is the biochemistry for transforming emulsion droplets into micelles? How does water, lipase, and other factors make these micelles? Fat (triglyceride) enters the small intestine in the form of an emulsion of droplets which are stabilised by surfactants from the diet including proteins and phospholipids.
Bile salts (BS) bind to the surface of these droplets, displacing proteins. The BS-stabilised droplets are the substrate for pancreatic lipase which can adsorb to the BS-stabilised surface and convert the triglycerides to monoglycerides and free fatty acids.
The products of lipolysis then enter micelles that are formed by BS and phosphatidylcholine (PC: also in bile). The prevailing view is that these micelles take the form of discs of bilayer-like structure with BS situated both around the edges protecting the exposed acyl groups, and also embedded within the PC bilayer.
I think that the mechanism by which the products of lipolysis move from BS/PC micelles into enterocytes is not known. However, once they have entered they are re-esterified to form triglycerides which are packaged into chylomicrons (a class of lipoproteins) and exported into the lymphatic system.
Maldonado-Valderrama et al. (2011) The role of bile salts in digestion. Adv Colloid Interface Sci. 165:36-46 doi: 10.1016/j.cis.2010.12.002
The following is multiple choice question (with options) to answer.
Bile salts produced by the liver assist in breaking apart what kind of fats? | [
"Sugar",
"soluble",
"dietary",
"carbohydrates"
] | C | Many other salts are important in the body. For example, bile salts produced by the liver help break apart dietary fats, and calcium phosphate salts form the mineral portion of teeth and bones. |
SciQ | SciQ-5440 | acoustics, doppler-effect
Title: Hearing sound when going supersonic Suppose we are travelling supersonic along a straight line. Further up along the line, there is a stereo, that's emitting sound at a frequency that changes in such a way that the Doppler shift caused by our supersonic travel in relation to the stereo effectively cancels out, and the sound is hence always maintained in our hearing range..
If the stereo is loud enough will we (no matter how ever briefly) be able to hear the sound at all? Yes, I think so. Since we don't have the source behind our backs, we will "meet" the sound and be able to hear it. When we pass the stereo, we will be able to hear the sound of the "stereo history" (i.e. already radiated) but not any "new one" (radiated post our flyby).
The following is multiple choice question (with options) to answer.
Where does most of the sound we hear travel through? | [
"air",
"the ground",
"light",
"water"
] | A | Most of the sounds we hear reach our ears through the air, but sounds can also travel through liquids and solids. If you swim underwater—or even submerge your ears in bathwater—any sounds you hear have traveled to your ears through the water. Some solids, including glass and metals, are very good at transmitting sounds. Foam rubber and heavy fabrics, on the other hand, tend to muffle sounds. They absorb rather than pass on the sound energy. |
SciQ | SciQ-5441 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
A reptile's what doesn't generate enough energy to keep their body temperature stable? | [
"tissue",
"respiration",
"skin",
"metabolism"
] | D | Like amphibians, reptiles are ectotherms with a slow metabolic rate. Their metabolism doesn’t generate enough energy to keep their body temperature stable. Instead, reptiles regulate their body temperature through their behavior. For example, the crocodile in Figure below is soaking up heat from the environment by basking in the sun. Because of their ectothermy, reptiles can get by with as little as one tenth the food needed by endotherms such as mammals. Some species of reptiles can go several weeks between meals. |
SciQ | SciQ-5442 | python, visualization, dataframe, graphs, matplotlib
# example data
x = list(range(14))
y1 = np.arange(14)
y2 = np.arange(14)[::-1]
y3 = [8 for x in range(14)]
# Interesting part
fig, ax = plt.subplots()
ax.bar(x, y1, color="red", edgecolor="None", linewidth=2, label='1')
ax.bar(x, y2, color="None", edgecolor="blue", linewidth=2, label='2')
ax.bar(x, y3, color="None", edgecolor="green", linewidth=2, label='3')
ax.legend()
plt.show()
The following is multiple choice question (with options) to answer.
Bar, circle, and line are examples of what kind of data visualization? | [
"maps",
"spreadsheets",
"formulas",
"graphs"
] | D | Graphs are very useful tools in science because they display data visually. Three commonly used types of graphs are bar graphs, circle graphs, and line graphs. Each type of graph is suitable for a different type of data. |
SciQ | SciQ-5443 | 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.
What is the first phase of mitosis? | [
"metaphase",
"telophase",
"prophase",
"meiosis"
] | C | The first and longest phase of mitosis is prophase . During prophase, chromatin condenses into chromosomes, and the nuclear envelope, or membrane, breaks down. In animal cells, the centrioles near the nucleus begin to separate and move to opposite poles (sides) of the cell. As the centrioles move, a spindle starts to form between them. The spindle, shown in Figure below , consists of fibers made of microtubules. |
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