source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-7444 | geology, crust, geobiology
Title: Does crustal thickness have anything to do with how life existed and sustained on Earth? The original question that was put on hold "If the crust were the thickest layer of Earth, what effect would its thickness have on organisms?" was actually one of those 'counterfactual question' found on my science book, and it was really just a 'reflect upon' question. And it's actually a hard one for me to answer since it's 'what if?'s. So by revising, it would still confuse some poeple, but I guess it's already specific on its own. But I still find it hard.
Follow up question:
And what if it ever was thicker than the mantle or the rest of Earth's layers, can the planet still sustain biological life? If the crust were the thickest layer or Earth, several things would happen:
It wouldn't be a "crust" any more, by definition. Because this is what a "crust" is: a thin layer on the exterior of something. However, if we assume that the mechanical properties of the crust (being cold and brittle etc) would extend deeper in the Earth, the following applies.
No mantle convection, or at least mantle convection weak enough to probably not affect the surface. Therefore, no volcanoes, no mountain building, no subduction, no recycling of volatile elements, no sub-seafloor hydrothermal vents.
If it's cold enough, the core probably solidified and there is no magnetic field.
A good example would be Mars. A planet hypothesised to have tectonic activity in the past, but not any more. The crust of Mars isn't the thickest layer (again - think of definitions), but it is thicker in absolute and relative terms when compared to Earth. I will leave the implications of "Marsifying" Earth on organisms for you to figure out.
The following is multiple choice question (with options) to answer.
What crust is thinner and denser than continental crust? | [
"asteroid",
"oceanic",
"coastal",
"land"
] | B | Oceanic crust is thinner and denser than continental crust. |
SciQ | SciQ-7445 | immunology, pathology, cardiology, hematology
Title: Human anti animal antibodies issues in blood testing Do people have to be exposed to animals to get HAMA antibodies? Can these antibodies impact blood tests with false negatives as well as false positives? You do not need to be exposed directly to animals to get human anti-mouse (or human anti-animal) antibodies; you can also be exposed to animal products in various ways.
Circulating anti-animal antibodies can arise from iatrogenic and noniatrogenic causes. The former is the result of the normal response of the human immune system to an administered “foreign” protein antigen. Currently available diagnostic and pharmaceutical agents derived from an animal source are extensive and range from rodent immunoglobulins to hormones isolated from fish. In addition, some recombinant proteins are affinity purified on immobilized monoclonal mouse antibody columns, and the possibility exists for some of the mouse monoclonal antibody to detach and copurify with the protein
You can also get anti-animal antibodies from blood transfusions:
Blood transfusion is also associated with an increased incidence of anti-animal antibodies. A study of 2829 participants in a population health survey revealed that 14.4% of the participants who had been transfused were anti-animal positive, compared with 10.4% of the participants who had never received a blood transfusion. This difference was presumably attributable to infusion of preexisting human anti-animal antibody or as a result of infusion of a foreign antigen present in the unit of blood
or through vaccination:
Vaccination against infectious diseases is another route by which animal protein antigens may be inadvertently presented to the immune system and trigger antibody formation. In the US, chick embryo or egg cultures are frequently used in vaccine production, and residual chicken protein may be present in vaccines, whereas in Europe, some vaccines contain rabbit serum, e.g., rubella vaccine in France, and multimicrobial vaccine (Bruschettini vaccine) in Italy
or "unconventional therapies":
The following is multiple choice question (with options) to answer.
What are the antibodies an animal produces after exposure to a microbial antigen? | [
"monoclonal",
"isolated",
"chimeric",
"polyclonal"
] | D | |
SciQ | SciQ-7446 | earth, thermal-radiation, thermal-conductivity
Title: Energy loss of Earth How does the Earth lose the energy that it gains from the sun's radiation if it is surrounded by - and in contact with - nothing? Matter above absolute zero will radiate (electromagnetic) energy no matter what. This is due to the motion of atoms (specifically charged subatomic particles) in the energized matter. Conduction between two bodies in thermal contact is only one means of transferring energy - it is different than radiation. The earth does not need to be in contact with anything to radiate energy.
The following is multiple choice question (with options) to answer.
How does heat travel from the sun to the earth? | [
"through light waves",
"through sound waves",
"thermal radiation from the sun",
"secondary radiation from the sun"
] | C | The bonfire from the opening image has a lot of thermal energy. Thermal energy is the total kinetic energy of moving particles of matter, and the transfer of thermal energy is called heat. Thermal energy from the bonfire is transferred to the hands by thermal radiation. Thermal radiation is the transfer of thermal energy by waves that can travel through air or even through empty space, as shown in the Figure below . When the waves of thermal energy reach objects, they transfer the energy to the objects, causing them to warm up. This is how the fire warms the hands of someone sitting near the bonfire. This is also how the sun’s energy reaches Earth and heats its surface. Without the energy radiated from the sun, Earth would be too cold to support life as we know it. |
SciQ | SciQ-7447 | evolution, biochemistry, life-history
Title: Was iron important for the first life on Earth? Some ions or compounds are thought not to have become involved or important in the metabolism of living organisms until some time after certain mutations took place. For instance, early life is thought to selectively allow calcium ions through its membrane, but eventually also evolved the ability to selectively allow sodium ions, specifically through a mutation that lead to a change in the composition of a channel protein from glutamine to lysine.
Currently, iron is involved in oxidations involving molecular oxygen, such as in cytochromes and clearly holds a key role in modern life, despite that free iron or even ferric compounds are rarely accessible. From my understanding, iron most likely became incorporated into the metabolism of microbes after during/after aerobic organisms had developed, but this does not rule out the possibility that iron was involved earlier on. So, I am wondering if iron was involved in early life, and details on how would be appreciated. Cyanobacteria require iron for photosynthesis and can be found as fossil stromatolites dating back to 3.5 billion years ago. Stromatolites are layered structures made up of cyanobacteria and sediment.
Source: https://en.wikipedia.org/wiki/Stromatolite
Modern stromatolites can be found at Shark Bay in Australia, Chetumal Bay in Belize, and Laguna Bacalar in the Yucatan Peninsula.
Cyanobacteria are also believed to have evolved into the first microbes to produce oxygen by photosynthesis, which was a catalyst for the Great Oxygenation Event which occurred around 2.45 billion years ago.
The following is multiple choice question (with options) to answer.
What were the first life forms found on earth similar to? | [
"bacteria",
"mold",
"viruses",
"ferns"
] | A | Life on Earth began about 3.5 to 4 billion years ago. The first life forms were single-celled organisms similar to bacteria. The first multicellular organisms did not appear until about 610 million years ago. Many different types of organisms evolved during the next ten million years, in an event called the Cambrian Explosion . This sudden burst of evolution may have been caused by some environmental changes that made the Earth's environment more suitable for a wider variety of life forms. |
SciQ | SciQ-7448 | inorganic-chemistry, metallurgy
Title: Does Gallium (liquid or solid) corrode all forms of brass? I know that it corrodes copper, but does it do the same to all brass or bronze compositions? From here
Gallium is corrosive to all metals except tungsten and tantalum, which have a high resistance to corrosion.
Beta-Brass is embrittled by Gallium
Due to its highly reducing character it is highly corrosive material.
The following is multiple choice question (with options) to answer.
Steel, bronze, and brass are examples of what? | [
"oxides",
"alloys",
"compounds",
"chemicals"
] | B | Pure metals may be less useful than mixtures of metals, called alloys. Examples of alloys include steel, bronze, and brass. |
SciQ | SciQ-7449 | convolution, cross-correlation, template-matching
A little bit about how is this task usually done:
Picking up the heart beats from an ECG signal usually involves rectification of the signal and sliding window integration with the possible addition of some filtering to reduce the effect of artefacts. The "ideal" result of this is a time series that looks like a square pulse with the positive transition of the pulse almost aligned with the start of the QRS complex and the negative transition of the pulse aligned with the end of the QRS complex. But in practice, you might find that this signal is more "floating" due to noise and artefacts which means that you might also have to use an adaptive threshold technique to improve the detection performance.
For more information please see this link. For much more information, including signals, please see this link.
Hope this helps.
The following is multiple choice question (with options) to answer.
A pacemaker uses electrical shocks to stimulate the what to beat properly? | [
"liver",
"pancreas",
"heart",
"brain"
] | C | Shock Hazards Electrical currents through people produce tremendously varied effects. An electrical current can be used to block back pain. The possibility of using electrical current to stimulate muscle action in paralyzed limbs, perhaps allowing paraplegics to walk, is under study. TV dramatizations in which electrical shocks are used to bring a heart attack victim out of ventricular fibrillation (a massively irregular, often fatal, beating of the heart) are more than common. Yet most electrical shock fatalities occur because a current put the heart into fibrillation. A pacemaker uses electrical shocks to stimulate the heart to beat properly. Some fatal shocks do not produce burns, but warts can be safely burned off with electric current (though freezing using liquid nitrogen is now more common). Of course, there are consistent explanations for these disparate effects. The major factors upon which the effects of electrical shock depend are 1. The amount of current. |
SciQ | SciQ-7450 | species-identification, mycology, mushroom
Title: Species ID: Buckyball-like fungus Previous research
A friend of mine shared a link of some beautiful fungi: https://i.stack.imgur.com/B81Pu.jpg. I was intrigued by the curious critter below -- it seems to have honed the power of buckyball geometry, presumably much before we Humans ever did (search: Buckminsterfullerene to learn about a feat of chemical engineering).
Google reverse-image search almost got me the answer I needed, but no species name.
I've asked friends on Facebook with no answers yet.
Question
What is the name of this species of fungus?
Related Questions on Stack Biology
Here's a related Species Identification question of a fungus: Puffball mushroom species ID? (by @rg255)
EDIT: I'm an idiot... the Imgur had species names, thus answering my question, post-mortem. Thanks @skymningen for pointing that out. Looks very similar to Clathrus ruber fungus.
Be careful, it is poisonous.
The following is multiple choice question (with options) to answer.
What is the cloud of brown dust-like power that escapes when a puffball fungus is touched? | [
"spores",
"ions",
"pollon",
"seeds"
] | A | This is a "puffball" fungus. At maturity, clouds of a brown dust-like power escape when they are touched. This powdery substance is made up of spores, the reproductive structure of the fungus. |
SciQ | SciQ-7451 | plant-anatomy
Title: Are bryophyte sporangia multicellular? My research on the matter can be summarized in a sentence: "It [sporangium] can be composed of a single cell or can be multicellular" (Source: https://en.wikipedia.org/wiki/Sporangium). Yet there shouldn't be a reply placed between "They are" and "They aren't" test options, speaking of "Are bryophyte sporangia multicellular?". A link to the source where I could ascertain whether the bryophyte sporangia is multicellular (if I could ascertain) is highly appreciated. In Embryophyta (land plants), including bryophytes, the sporangium is usually a multicellular structure.
Perhaps you meant to ask about the number of spore mother cells (SMCs) in each sporangium? That varies across groups. In bryophytes, each sporangium has many SMCs, and accordingly produces a large number of spores. (Contrast this with angiosperms, where a megasporangium [called an ovule] has only one megaspore mother cell.)
References and further reading:
https://courses.lumenlearning.com/boundless-biology/chapter/bryophytes/
https://www.britannica.com/science/plant-development
Image attribution:
By LadyofHats. (Public domain;
https://commons.wikimedia.org/wiki/File:Hornwort_structures.jpg)
The following is multiple choice question (with options) to answer.
What are the cone-like structures that contain sporangia called? | [
"contrail",
"gametes",
"medulla",
"strobili"
] | D | Leaves, Sporophylls, and Strobili A third innovation marks the seedless vascular plants. Accompanying the prominence of the sporophyte and the development of vascular tissue, the appearance of true leaves improved their photosynthetic efficiency. Leaves capture more sunlight with their increased surface area by employing more chloroplasts to trap light energy and convert it to chemical energy, which is then used to fix atmospheric carbon dioxide into carbohydrates. The carbohydrates are exported to the rest of the plant by the conductive cells of phloem tissue. The existence of two types of morphology suggests that leaves evolved independently in several groups of plants. The first type of leaf is the microphyll, or “little leaf,” which can be dated to 350 million years ago in the late Silurian. A microphyll is small and has a simple vascular system. A single unbranched vein—a bundle of vascular tissue made of xylem and phloem—runs through the center of the leaf. Microphylls may have originated from the flattening of lateral branches, or from sporangia that lost their reproductive capabilities. Microphylls are present in the club mosses and probably preceded the development of megaphylls, or “big leaves”, which are larger leaves with a pattern of branching veins. Megaphylls most likely appeared independently several times during the course of evolution. Their complex networks of veins suggest that several branches may have combined into a flattened organ, with the gaps between the branches being filled with photosynthetic tissue. In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls—leaves that were modified structurally to bear sporangia. Strobili are cone-like structures that contain sporangia. They are prominent in conifers and are commonly known as pine cones. |
SciQ | SciQ-7452 | quantum-gravity, physical-constants
Title: What is the smallest existing thing in theory and law? What is the smallest existing thing in theory and law?
"What is the smallest existing thing in theory and law?"
The Merriam Webster Dictionary defines a "thing" as:
: an object or entity not precisely designated or capable of being
designated
a: an inanimate object distinguished from a living being
b: a separate and distinct individual quality, fact, idea, or usually
entity
c: the concrete entity as distinguished from
...
A Photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force (even when static via virtual particles). Mass: 0 < 1×10−18 eV/c^2.
The photon has zero rest mass and always moves at the speed of light within a vacuum. Since the Photon is a Point Particle and has a size of zero you might say it's not a thing, nothing; that leaves us with:
The smallest real thing is the Neutrino. Mass: ≤ 0.120 eV/c^2.
The smallest theoretical thing is the Planck Particle. Radius: 5.72947×10−35 m, Mass: 3.85763×10−8 kg.
The following is multiple choice question (with options) to answer.
What are considered to be the smallest particles of matter? | [
"ions",
"atoms",
"cells",
"molecules"
] | B | All substances are made of atoms. Atoms are the smallest particles of matter. They cannot be divided into smaller particles, created, or destroyed. |
SciQ | SciQ-7453 | proteins, enzymes, cellular-respiration
Earlier models proposed simple rotational diffusion of a rigid c12 ring, possibly driven by electrostatic forces. The structural data on protonation-linked conformational changes in subunit c indicate that the process may be more mechanical, with local rotations within subunit c driving larger-scale rotations of the c12 oligomer as a whole, in a `wheels within wheels' type of mechanism.
The whole paper's a good read. But this is as current as I am on the topic, and it's likely that a more detailed mechanism has been determined for the action of ATP synthase since 1999.
The following is multiple choice question (with options) to answer.
The mechanics of dynein-based bending involve a process that resembles what? | [
"running",
"standing",
"jumping",
"walking"
] | D | |
SciQ | SciQ-7454 | species-identification, zoology, marine-biology, arthropod
Title: What is this large, lively barnacle? Yesterday I found this creature in a rocky cove in central California, around mid tide (+ 3 feet). It's about 3-4 inches long. At first I thought it was dead, but it closed its mouth when I removed the tiny white pebble, and rotated the operculum rapidly when I poked the bit of exposed yellowish flesh underneath. I think it's some sort of acorn barnacle, but haven't been able to identify a species with the white shell and distinctive red-and-white color and texture differences on the opercular plates. What could it be? Update: this is a giant acorn barnacle, Balanus nubilis. Between Pacific Tides mentions that they can vary widely in coloration, and there's a picture of a similarly colored one here.
We had our ID confirmed by email by a representative of the Monterey Bay Aquarium, who added this info:
You beat me to it. That is indeed a giant acorn barnacle (Balanus
nubilus). Unfortunately, barnacles can’t survive long after being
detached from their rocks and they’re unable to reattach on their own.
Rocky intertidal zones are harsh environments and animals living in
these areas must deal with both water and air, rapidly changing
temperatures, exposure to sunlight, desiccation, high wave energy, and
predators from both land and sea.
The stringy threads attached to the barnacle in your photo are the
byssal threads of California mussels. Mussels secrete these threads
to anchor themselves to rocks, each other, barnacles, etc. It’s very
common to see mussels and barnacles clumped together in high surf
zones.
The following is multiple choice question (with options) to answer.
What type of creature is a scallop? | [
"vertabrate",
"algae",
"insect",
"mollusk"
] | D | Some mollusks, such as oysters and scallops, are important food sources. |
SciQ | SciQ-7455 | the-sun, photography, solar-eclipse
I can see how the enlarged image of the Sun through a telescope or binoculars might overwhelm the eclipse glasses' filters.
A few observations.
It's really the larger aperture of the instrument that is the problem here. The pupil of your eye is only a few mm in diameter. The objective lens or mirror of a telescope could be anywhere between dozens of mm to hundreds of mm (or thousands for very large instruments). The ratio of areas between telescope aperture and eye pupil is even greater - it's the square of the ratio of diameters.
Let's say your eye's pupil is 2 mm in diameter. Let's say you use a 50 mm aperture telescope (small refractor or binoculars). The diameter ratio is 25x. The area ratio is 625x.
All the light captured by the very large area of the instrument is funneled into your eye through your pupil. With the instrument, now you're getting 625x more energy from the Sun, compared to the naked eye view. It's already dangerous to look at the Sun with the naked eye - with the instrument it's 625x more dangerous. And this is with a very small refractor.
There is a class of "solar filters" that are made to be mounted on the instrument's eyepiece, or after the eyepiece. THESE ARE VERY DANGEROUS! All the increased, focused energy of the Sun is now absorbed by the filter, which can warp, melt, crack, or burst into flames. A filter failure at this point is likely to injure the user. White light filtering for solar observations must always occur ahead of the instrument, not after it.
As for why classic, optical viewfinders were included in that list: it was out of an abundance of caution. Most of those viewfinders do not capture more light than your eye does, but some do. It's better to be safe than sorry. You can't expect everyone to be able to tell whether their viewfinder is dangerous or not. So, in a warning addressed to the general population, just tell them to stay away from it.
Now, if you install a full-aperture solar filter (like the Baader solar film) ahead of the viewfinder, then it's safe to use - provided the filter is attached firmly to the camera and cannot be blown away by some random gust of wind.
The following is multiple choice question (with options) to answer.
The risk of what is raised by overexposure to the sun? | [
"skin cancer",
"particle cancer",
"flux cancer",
"brain cancer"
] | A | It might be fun to lay out in the sun like these two girls are doing. But getting too much sun can be very dangerous. Overexposure to sunlight raises your risk for skin cancer. |
SciQ | SciQ-7456 | human-biology, human-anatomy, human-ear
Title: What is the course of inter auricular line? BACKGROUND: The interauricular line is the line connecting two auricles.
I wish to know the exact route through which this line passes. I want to be sure whether it passes through the parietal prominences, or in front of them. Up front - I have never heard of this term and I could not find information on the interauricular line. The only thing I was able to dig up was the term auricular line, which is (Fig. 1):
[The] [l]ine pass[ing] perpendicular to the anthropological baseline,
through the cent[er] of the external auditory meatus.
Fig. 1. Auricular line. source: Radiology Key
The anthropological line being (Fig. 2):
[The] [l]ine join[ing] the infraorbital margin to the superior border
of the external auditory meatus.
Fig. 2. Anthropological line. source: Radiology Key
The following is multiple choice question (with options) to answer.
Which artery enters the cranium through the carotid canal in the temporal bone? | [
"external carotid",
"atrial artery",
"internal carotid artery",
"venal artery"
] | C | The internal carotid artery enters the cranium through the carotid canal in the temporal bone. A second set of vessels that supply the CNS are the vertebral arteries, which are protected as they pass through the neck region by the transverse foramina of the cervical vertebrae. The vertebral arteries enter the cranium through the foramen magnum of the occipital bone. Branches off the left and right vertebral arteries merge into the anterior spinal artery supplying the anterior aspect of the spinal cord, found along the anterior median fissure. The two vertebral arteries then merge into the basilar artery, which gives rise to branches to the brain stem and cerebellum. The left and right internal carotid arteries and branches of the basilar artery all become the circle of Willis, a confluence of arteries that can maintain perfusion of the brain even if narrowing or a blockage limits flow through one part (Figure 13.15). |
SciQ | SciQ-7457 | taxonomy
Title: Why are sponges sometimes not considered multicellular? I read somewhere (I can't find where) that there is no scientific consensus whether sponges should be considered multicellular organisms.
It seems I don't understand where is the line between unicellular and multicellular life.
I am not able to find a more elaborate explanation of that doubt. What are the reasons for it? Sponges are generally considered as colonial organisms because there is little cell specialization and little separation of function/role. All cells do pretty much the same thing; it looks more like a pile of individual cells than an actual multicellular organism. In reality it is a little bit in between.
In any case, what one wants to call multicellular or unicellular is a matter of definition and preferences. You cannot find the line between unicellular and multicellular because there is no such line that would not be very arbitrary and filled with special cases.
You can study a little more the physiology of sponges and then decide for yourself if it looks sufficiently like a multicellular organism or more like a colony of cells (a colonial organism).
The following is multiple choice question (with options) to answer.
How are aquatic biomes often classified? | [
"amount of light",
"depth",
"amount of life",
"amount of salt"
] | D | Recall that terrestrial biomes are defined by their climate. That's because plants and animals are adapted for certain amounts of temperature and moisture. However, would aquatic biomes be classified in the same way? No, that wouldn't make much sense—all parts of an aquatic environment have plenty of water. Aquatic biomes can be generally classified based on the amount of salt in the water. Freshwater biomes have less than 1% salt and are typical of ponds and lakes, streams and rivers, and wetlands. Marine biomes have more salt and are characteristic of the oceans, coral reefs, and estuaries. |
SciQ | SciQ-7458 | genetics, genomes, complexity
Title: What is the most genetically complex organism? I understand that new genomes are being sequenced ever day and these answers replace themselves often; although as of today, what has been proven to be the most genetically complex organism (Other than a human of course)? I keep getting a multitude of different answers like Daphnia pulex, Axolotl, Paris japonica or Adder’s Tongue all from different dates and sources so it becomes difficult to tell what is the right answer here if any. If this question is not specific enough I would be happy to revise.
Edit: I would define genetic complexity as either genome size or number of genes. Either answer would work. If you would like give other information like chromosomes or isoforms from any other definition, that would be helpful. Whatever is the best of the best.
Edit: I would define genetic complexity as either genome size or number of genes. Either answer or information would work.
Largest genome: Paris japonica, a rare plant. Its genome is 149,000,000,000 base pairs large. Approximately 50 times larger than the human genome, by base pair count.
Higher number of genes in an organism: Daphnia pulex, a very common species of water flea. 31,000 protein-coding genes.
As already pointed out, the most genetically complex organism is an unclear question. Complexity can be interpreted in different ways, and I don't think we could agree on a satisfying measure (or definition, for that matter) of genetic complexity.
The following is multiple choice question (with options) to answer.
What is the most abundant type of biological entity on the earth? | [
"bacteria",
"viruses",
"reptiles",
"insects"
] | B | Viruses were first described by Dmitri Ivanovsky in 1892. He described a "non-bacterial pathogen" infecting tobacco plants. This was soon followed by the identification of the tobacco mosaic virus by Martinus Beijerinck in 1898. Since then, about 5,000 viruses have been described in detail, although it is believed that there are millions of different types. Viruses are found in almost every ecosystem on Earth, and are the most abundant type of biological entity. Viruses can be classified with a taxonomic structure from order to species. No kingdom classification exists. Viruses, not being made of cells, do not fall into any of the six prokaryotic or eukaryotic kingdoms. |
SciQ | SciQ-7459 | microbiology, population-biology
Title: How many eukaryotes are there on Earth? I have been reading:
William B. Whitman, David C. Coleman, and William J. Wiebe, "Prokaryotes: The unseen majority", Proc. Natl. Acad. Sci. USA 95, pp. 6578–6583, June 1998. [Full Text] [PDF]
wherein they estimate the number of prokaryote cells on Earth to be of the order of $10^{31}$.
I can't seem to find any equivalent data for eukaryote one-celled life. Are there any estimates for the number of one-celled eukaryotic living things on Earth? Do any other estimates confirm or tell against the reference I have cited above? Could not fit in a comment....
To make sure we all understand your question...
Is your question how many (eukaryote) species are currently living? or How many (eukaryote) cells are currently living??
Just a hint to answer the question
Micheal Lynch, in his book (On the Origin of Genome Architecture) at page 3, Box 1.1 tries to answer the question How much DNA is there on earth?. He ends up with an estimation of a total length of DNA on earth of $10^{24}$ km for procaryotes, $10^{25}$ km for eukaryote (of which $\frac{1}{1000}$% is accounted to humans). This sums up to a total DNA length of $10^{12}$ light-years, or 10 times the diameter of the known universe!
In his calculations, he estimates that the total number of procaryote cells at $10^{30}$ (citing Whitman et al. 1998 as you did). He estimates the total number of eukaryote species to $10^7$, i.e. 6 times the number of known eukaryote species. However, he doesn't directly give any reference for this estimate but he refers to different chapters in the book that contain lots of references.
...I hope that helps...
The following is multiple choice question (with options) to answer.
What is the most diverse and abundant group of organisms on earth, numbering in the millions of trillions? | [
"viruses",
"pathogens",
"pests",
"bacteria"
] | D | Bacteria are the most diverse and abundant group of organisms on Earth. They live in almost all environments. They are found in the ocean, the soil, and the intestines of animals. They are even found in rocks deep below Earth’s surface. Any surface that has not been sterilized is likely to be covered with bacteria. The total number of bacteria in the world is amazing. It’s estimated to be 5 × 10 30 , or five million trillion. You have more bacteria in and on your body than you have body cells!. |
SciQ | SciQ-7460 | endocrinology, enzymes
Title: Renin - enzyme or hormone? Wikipedia says :
The kidneys secrete a variety of hormones, including erythropoietin,
and the enzyme renin.
Can a substance be both an enzyme and a hormone ? Why is renin both an enzyme and a hormone ? Yes, something can be both a hormone and an enzyme. There are a group of hormones known as peptide hormones. These are proteins (such as enzymes) that act as hormones indirectly (and maybe directly too?). A hormone is a chemical secreted by a cell that has some effect on another cell elsewhere in the body. In this case, the chemical just happens to be an enzyme. You can read about them on Wikipedia
Renin is secreted by the kidney, but its involved in arterial vasoconstriction (outside of kidney cells), so it is a hormone. And its also a peptide/enzyme, so it is considered both a hormone and an enzyme
The following is multiple choice question (with options) to answer.
What kind of hormones are secreted by organs classified as gonads? | [
"growth hormones",
"cortisol hormones",
"anterior hormones",
"sex hormones"
] | D | The gonads secrete sex hormones. The male gonads are called testes. They secrete the male sex hormone testosterone. The female gonads are called ovaries. They secrete the female sex hormone estrogen. Sex hormones are involved in the changes of puberty. They also control the production of gametes by the gonads. |
SciQ | SciQ-7461 | gas-laws, heat
Title: How can I light a fire in this case? Is there any gas that contains oxygen so that it doesn't require oxygen from the environment in order to burn?
What I am trying to do is use LPG gas, which is fed through a pipe to a burner that is placed in an environment that has no air, somewhat like a vacuum. Is there any way to light the burner inside that vacuum environment?
A few wild ideas that I had included finding some gas that contains oxygen in itself. I may be wrong.
EDIT - The question doesn't end here. Please read the comments section below for any doubts that you might have. And if it isn't answered in comments section then ONLY comment. The most convenient solution for your question can be the Hydrooxy gas (also sometimes called the Brown’s gas). Simply put its water split into hydrogen and oxygen. Hydrogen and oxygen can be combined back by ignition and can create a maximum temperature up to 2800 °C (around 600–700 °C hotter than burning hydrogen in air), which makes it a good fuel for metal welding and cutting.
Though 2:1 hydrogen and oxygen ratio is enough to produce water via combustion, but on a practical solution you will need around 3:1 to 5:1 ratio to avoid oxidizing flames. The temperature you can achieve by burning hydrogen oxygen mix varies, depending on the ratio of both gases used.
Hydrogen and oxygen can be obtained via simple electrolysis.
$$\ce{2H2O + Energy -> 2H2 + O2}$$
and combined back as
$$\ce{2H2 + O2 -> 2H2O + Energy}$$
It might be worth noting that for all practical purposes, the energy you use to split hydrogen and oxygen will always be greater than what you can get by combining them back (like what happens in every combustion engine, humans have ever created).
If you are planning to develop an actual application, there are many precautions that you would need to consider, the most important of which would be back-fire protection (a common problem with gas based welding), so that the flame doesn’t reach back into the gas tank, which of course will explode.
The following is multiple choice question (with options) to answer.
An oxy-acetylene torch is an effective way to cut what? | [
"metal",
"plastic",
"coal",
"wood"
] | A | One of the most effective ways to cut metal is with an oxy-acetylene torch. Very high temperatures are obtained when acetylene burns in oxygen. Mixed 1:1 with oxygen, a temperature of over 3000°C can be achieved. The amount of energy released is high – the net heat of combustion is 1300 kJ/mole. Safety precautions need to be observed since the gas is very explosive. For welding and cutting, the oxy-acetylene torch is one of the best ways to go. |
SciQ | SciQ-7462 | mitochondria
Title: Are porins on the inner or on the outer membrane of mitochondria? I've looked at multiple resources and they are saying different things. This is not my field, but The Transporter Classification Database would appear to be a reliable source and states that:
The best characterized members of the MPP family are the voltage-dependent anion-selective channel (VDAC) porins in the mitochondrial outer membrane.
Searching through the Protein Data Bank one can find a crystal structure for human voltage-dependent anion channel 1 and the associated paper also states that it is in the outer mitochondrial membrane, so you would imagine that they should know.
The following is multiple choice question (with options) to answer.
What are the infoldings of the inner membrane called? | [
"lineage",
"cristae",
"ceranae",
"brickle"
] | B | |
SciQ | SciQ-7463 | physical-chemistry, biochemistry, energy
Title: Explicit differential equation based model of protein folding I am an applied mathematician interested in the dynamics of potential systems - i.e., systems with multiple unique energy minima. One of the best examples of such systems are protein folding potentials. From sources like This one I know that the potential,
$$
V(x)
$$ exists and is a function of the positions of each residue in space and their interactions with each other. Since such a function exists, there should (mathematically) be a set of ordinary differential equations that capture the dynamics described by the potential.
However, although I have seen definitions of $V(x)$ in the literature, for the life of me I can't figure out exactly what the set of differential equations associated with this system is - i.e., the system is usually written out in a generalized form that applies to all proteins, but the exact information required to build such a potential for one such protein is unclear.
Does anyone have an example of of a particular $V(x)$ (for a particular, short, set of amino acids, say) where all the parameters are known and the system can be solved numerically as a set of ordinary differential equations? What you are looking for is a force field: http://en.wikipedia.org/wiki/Force_field_(chemistry)
Standard force fields for proteins include CHARRM and AMBER. These have relatively simple, well-defined expressions for defining the various types of interactions between bonded and non-bonded atoms. Parameters are available for all standard atom types, and are fit to experimental and/or electronic structure calculations. These force fields are considered "classical" in that they do not explicitly treat electronic interactions, but rather try to capture these interactions in a coarse-grained way. Typically, there are expressions for describing the following interactions:
bonded interactions (bond stretching)
angle interactions (bond bending)
torsion interactions (dihedral bending)
12-6 Lennard-Jones interactions (non-bonded, dispersion forces)
Short-range charge-charge interactions (Coulombic interactions between charged or partially charged atoms)
Long-range charge-charge interactions (see Ewald summation method for more details)
The following is multiple choice question (with options) to answer.
A channel protein is an example of what type of protein? | [
"transport proteins",
"component proteins",
"hemoglobin protein",
"choice proteins"
] | A | Facilitated diffusion is the diffusion of solutes through transport proteins in the plasma membrane. Channel proteins, gated channel proteins, and carrier proteins are three types of transport proteins that are involved in facilitated diffusion. |
SciQ | SciQ-7464 | meteorology, climate-change, temperature, seasons
Title: How is this global temperature chart compiled? In this BBC News article, there is a chart labelled "Hottest day on record globally - Daily average air temperature, 1940-2023". It shows temperatures that are higher in summer and lower in winter for the northern hemisphere, which leads me to wonder what exactly this chart is showing. If it were a global average, would the temperature in summer (or winter) not be offset by the fact that the other side of the globe has its winter (or summer) at the same time?
So what is the method used in this chart? Is it just for the northern hemisphere? Is it the temperature over the land mass but not over the sea? Is the data for the southern hemisphere offset by half a year? Or is the world actually hotter in July because there's more land mass in the nothern hemisphere? As stated in your linked article, the graph shows the global average temperature based on ERA5 reanalysis data.
Typically for graphs like this you integrate the surface temperature over the whole domain (surface of earth) and normalise the result with Earth's surface area.
A short explanation for the seasonal cycle is that the northern hemisphere has more land surface area (less water surface area) compared to the southern hemisphere. Water surfaces heat much slower than land surfaces, which introduces a phase lag with respect to the solar heating. Very simplified think about it like this: High solar radiation in the southern hemisphere leads to high temperatures a few weeks/months later, while in the northern hemisphere high temperatures coincide with high radiation levels. This leads to the sinusoidal pattern you observed in the graph.
In the introduction of this article you can find many nice references if you are interested in some more details. Apparently, this has been textbook knowledge since at least 1903.
The following is multiple choice question (with options) to answer.
Eight of the hottest years on record have occurred since what year? | [
"1998",
"2002",
"1991",
"1997"
] | A | Since the mid 1800s, Earth has warmed up quickly. Look at Figure below . The 14 hottest years on record have all occurred since 1900. Eight of them have occurred since 1998! This is what is usually meant by global warming . |
SciQ | SciQ-7465 | kinematics, acceleration, rotation
Yes, in fact they're almost completely unrelated.
The average acceleration is defined as
$$\vec a_\text{avg} = \frac{\Delta\vec v}{\Delta t}$$
It is one quantity that partially describes the motion of a particle over an extended time. In other words, average acceleration encapsulates the fact that a particle started with some velocity at time A and ended with some velocity at time B, but completely ignores what the particle did between A and B. This is by design.
Centripetal acceleration, on the other hand, is an instantaneous quantity: it's the radial component of acceleration. (This requires that you have chosen some point to be the center of a polar coordinate system.) It partially describes the motion of a particle at one moment, not over an extended time.
The following is multiple choice question (with options) to answer.
Average acceleration is the rate of change of what? | [
"direction",
"displacement",
"velocity",
"speed"
] | C | Average acceleration is the rate of change of velocity, or the change in velocity per unit time. |
SciQ | SciQ-7466 | gene-expression, gene, gene-regulation
Title: Can gene-gene interactions result in gene expression? I am building a project on Inferring Gene Regulatory Networks using ARACNE and PCA-CMI algorithms, and the input to these algorithms is taken from the DREAM3 challenge.
The format of the input data is shown in the image.
Now according to what I studied, a Gene Expression Matrix has its rows represent genes, columns represent samples such as tissues or experimental conditions and the numbers in each cell refer to the expression level of a particular gene in the particular sample.
And that Gene Expression is the process in which information from a gene is synthesized to obtain Gene Products. The process of Gene Expression is that it undergoes a transcription process where a transcription factor attaches itself to the gene and then results in the formation of gene product.
But the input data apparently shows gene-gene interactions.
As a result of this I am extremely confused.
Any kind of help would be greatly appreciated. Thanks. I don't know anything about your algorithms. But i will try to explain your the format of data that was given to you. I don't know your background in Biology, so i will assume it is not your expertise field and will make some simplifications of the subject.
What is gene expression?
To understand what is a gene expression, you need to understand what is a gene:
A gene is a sequence in the DNA (composed of 4 bases A,T,C and G) that can be transcribed by a protein, in your context we will say it always start with a start codon (a codon is a triplet of DNA bases) and stop with a stop codon. It is usually around a thousand bases long. The transcription will give you a RNA, and that RNA can be translated (note the difference with transcribed) into a whole new protein.
Now the gene Expression is a measure of the amount of RNA from the gene you are looking for. In a cell you can have around 10000-100000 copies of that RNA; the raw count is not really stable as you can have extract two cells or three and it will change your "expression". Most of the time we normalize the count by the count of a bunch of known genes called housekeeping genes. The particularity of these genes is that their expression is quite stable.
The figures you have are a ratio between RNA copies of your gene of interest and RNA copies of a stable gene (in term of expression).
The following is multiple choice question (with options) to answer.
What is studied to understand gene expression patterns in cells? | [
"rna",
"dna",
"mutations",
"protein"
] | A | RNA is studied to understand gene expression patterns in cells. RNA is naturally very unstable because enzymes that break down RNA are commonly present in nature. Some are even secreted by our own skin and are very difficult to inactivate. Similar to DNA extraction, RNA extraction involves the use of various buffers and enzymes to inactivate other macromolecules and preserve only the RNA. Gel Electrophoresis Because nucleic acids are negatively charged ions at neutral or alkaline pH in an aqueous environment, they can be moved by an electric field. Gel electrophoresis is a technique used to separate charged molecules on the basis of size and charge. The nucleic acids can be separated as whole chromosomes or as fragments. The nucleic acids are loaded into a slot at one end of a gel matrix, an electric current is applied, and negatively charged molecules are pulled toward the opposite end of the gel (the end with the positive electrode). Smaller molecules move through the pores in the gel faster than larger molecules; this difference in the rate of migration separates the fragments on the basis of size. The nucleic acids in a gel matrix are invisible until they are stained with a compound that allows them to be seen, such as a dye. Distinct fragments of nucleic acids appear as bands at specific distances from the top of the gel (the negative electrode end) that are based on their size (Figure 10.3). A mixture of many fragments of varying sizes appear as a long smear, whereas uncut genomic DNA is usually too large to run through the gel and forms a single large band at the top of the gel. |
SciQ | SciQ-7467 | cell-biology
Title: Are ribosomes assembled in rough ER and Golgi body, or in the nucleolus? I mean all the components, such as ribosomal RNA (rRNA) are synthesized in the nucleolus, but is the whole ribosome structure assembled in the nucleolus or is it also done in the rough endoplasmic reticulum and Golgi apparatus? Ribosome assembly starts in the nucleolus (of eukaryotes) and finishes in the cytoplasm. However, in the cytoplasm the Golgi apparatus is certainly not involved, and, as some cells have little rough endoplasmic reticulum, assembly does not require that. Thus, the abstract of a review by Fromont-Racine et al. in Gene (2003) vol 313 pp. 17–42 starts with the statement:
Ribosome synthesis is a highly complex and coordinated process that occurs not only in the nucleolus but also in the nucleoplasm and the cytoplasm of eukaryotic cells.
In the 26 pages of this review there is not a single mention of the words ‘endoplasmic reticulum’ or ‘Golgi’.
A more recent (and freely available) review by Thomson et al. in Journal of Cell Science (2013) vol 126 pp. 4815-4820 is in accord with this. It has a pretty poster insert which presents the assembly as a succession of events, starting in the nucleolus, proceeding to the nucleoplasm, and with some final polishing in the cytoplasm.
The following is multiple choice question (with options) to answer.
Ribosomes are produced in the nucleolus, and then transported to the what? | [
"cerebellum",
"cytoskeleton",
"nucleus",
"cytoplasm"
] | D | Ribosomes are produced in the nucleolus, and then transported to the cytoplasm. Ribosomes are made of ribosomal proteins, called ribonucleoproteins , and ribosomal RNA (rRNA). Each ribosome has two parts, a large and a small subunit, as shown in Figure below . The subunits are attached to each other. During translation, the smaller subunit binds to the mRNA, while the larger subunit binds to the tRNA with attached amino acids. When a ribosome finishes reading an mRNA molecule, the two ribosomal subunits disassociate. |
SciQ | SciQ-7468 | 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.
Ecosystem dynamics include more than the flow of energy and recycling of matter. ecosystems are also dynamic because they? | [
"recreate exactly alike",
"change through time",
"never move",
"stay the same"
] | B | Ecosystem dynamics include more than the flow of energy and recycling of matter. Ecosystems are also dynamic because they change through time. |
SciQ | SciQ-7469 | biochemistry, physiology, muscles
Title: How is ATP involved in muscle contraction? The sliding filament mechanism as explained by my text does not elaborate on how ATP is involved in the cross bridge binding and contraction process. How does muscle contraction utilize ATP?
In my text explains this is the procedure for a contraction:
Ach released by motor neuron cross cleft and binds to motor end
plate
AP generated in response to binding of Ach gated channels and propagates down T tuble
T tuble triggers Ca2+ from sarcoplasmic reticulum
Ca2+ binds onto tropinin on actin filament and removes tropomyosin
This opens up sites for myosin to attach to actin using protein heads
Actin filament is pulled toward the center of sarcomere, causing contraction
I see that the action potential definitely needs ATP in order to be generated, aside from that I am surprised that the actual contraction via cross bridge binding does not seem to need ATP.
ATP prepares myosin for binding with actin by moving it to a
higher-energy state and a "cocked" position.
Once the myosin forms a cross-bridge with actin, the Pi disassociates
and the myosin undergoes the power stroke, reaching a lower energy
state when the sarcomere shortens.
ATP must bind to myosin to break the cross-bridge and enable the
myosin to rebind to actin at the next muscle contraction.
The following is multiple choice question (with options) to answer.
Muscle contraction requires repeated cycles of binding and what? | [
"release",
"twisting",
"push",
"lunging"
] | A | |
SciQ | SciQ-7470 | 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.
An important chemical compound, which supplies living things with the energy they need to survive, is composed of carbon, oxygen and atoms of what other element? | [
"magnesium",
"nitrogen",
"calcium",
"hydrogen"
] | D | The opening image is a model of an important chemical compound. Without it, living things would not have the energy they need to survive. Compared with most other compounds in living things, molecules of this compound are small and simple. In the model, the gray circles represent carbon atoms, the red circles represent oxygen atoms, and the black circles represent hydrogen atoms. |
SciQ | SciQ-7471 | human-biology, immunology, antibody
Title: Transfer of antibodies in breast milk of humans Why isn't the IgA secreted in breast milk digested due to proteases of the digestive system in the baby?
Wikipedia says:
The secretory component of sIgA protects the immunoglobulin from being
degraded by proteolytic enzymes, thus sIgA can survive in the harsh
gastrointestinal tract environment and provide protection against
microbes that multiply in body secretions.
But what exactly does the secretory component do? What is the secretory component? Is IgA absorbed in the circulation of fetus? I remember reading it somewhere that it is not absorbed, at least in humans. Please answer these questions focusing more on humans. Though, information about other animals will be appreciated as well. It is! Here is an amazing review from 2011 that literally has all the answers. I'm not kidding, all of them. I would marry this review if I could.1 It also includes information on other animals.
The main takeaway is that IgA from milk is not readily absorbed by the infant body. Secreted IgA is mainly to provide a protective coating for the mucosa while the infant is developing its own nascent immune system. IgG passed along from the placenta (your other question) provides the main source of absorbed antibodies. As it says in the review:
Milk sIgA is not taken up by the infant’s intestinal mucosa. In fact, gut closure in humans occurs before birth and little immunoglobulin is absorbed intact in the intestine after birth. However, the presence of sIgA in the intestinal lumen is part of the protective function of the epithelial barrier in the intestine... Secretory IgA is considered to be the primary immunoglobulin responsible for immune protection of mucosal surfaces such as the intestine.
In terms of enzymatic activity, the digestive system will in indeed chomp up the antibodies; that's part of the reason breast feeding should continue as needed. That's okay, because there's plenty to go around:
Much of the immunoglobulin consumed in an immune milk can be expected to be partially or completely digested, however some portion of the immunoglobulin will remain intact or at least partially intact and capable of binding to an antigen.
The following is multiple choice question (with options) to answer.
What are the glands that secrete milk in a woman's breasts? | [
"pituitary glands",
"primordial glands",
"mammary glands",
"lactic acids"
] | C | The breasts are not directly involved in reproduction, but they nourish a baby after birth. Each breast contains mammary glands , which secrete milk. The milk drains into ducts leading to the nipple. A suckling baby squeezes the milk out of the ducts and through the nipple. |
SciQ | SciQ-7472 | javascript, css, sass
<p>Vestibulum purus quam, scelerisque ut, mollis sed, nonummy id, metus. Nullam accumsan lorem in dui. Cras ultricies mi eu turpis hendrerit fringilla. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; In ac dui
quis mi consectetuer lacinia. Nam pretium turpis et arcu. Duis arcu tortor, suscipit eget, imperdiet nec, imperdiet iaculis, ipsum. Sed aliquam ultrices mauris. Integer ante arcu, accumsan a, consectetuer eget, posuere ut, mauris. Praesent adipiscing.
Phasellus ullamcorper ipsum rutrum nunc. Nunc nonummy metus. Vestibulum volutpat pretium libero. Cras id dui. Aenean ut eros et nisl sagittis vestibulum. Nullam nulla eros, ultricies sit amet, nonummy id, imperdiet feugiat, pede.</p>
<p>Li Europan lingues es membres del sam familie. Lor separat existentie es un myth. Por scientie, musica, sport etc, litot Europa usa li sam vocabular. Li lingues differe solmen in li grammatica, li pronunciation e li plu commun vocabules. Omnicos directe
al desirabilite de un nov lingua franca: On refusa continuar payar custosi traductores. At solmen va esser necessi far uniform grammatica, pronunciation e plu sommun paroles.</p>
The following is multiple choice question (with options) to answer.
Like a thick cap covering the brain, the dura mater is a tough outer covering. the name comes from the latin for? | [
"tough mother",
"protecting mother",
"back mother",
"difficult mother"
] | A | Dura Mater Like a thick cap covering the brain, the dura mater is a tough outer covering. The name comes from the Latin for “tough mother” to represent its physically protective role. It encloses the entire CNS and the major blood vessels that enter the cranium and vertebral cavity. It is directly attached to the inner surface of the bones of the cranium and to the very end of the vertebral cavity. There are infoldings of the dura that fit into large crevasses of the brain. Two infoldings go through the midline separations of the cerebrum and cerebellum; one forms a shelf-like tent between the occipital lobes of the cerebrum and the cerebellum, and the other surrounds the pituitary gland. The dura also surrounds and supports the venous sinuses. |
SciQ | SciQ-7473 | biochemistry, food
Title: Who creates first nitrogen compounds in the food supply chain As I understand the food supply chain, organic compounds have to be created from a unlimited source (air, water...).
For instance, I figure that plants transform CO2 from air to organic carbon compounds, mainly carbohydrates, which are then the main source for most other life forms.
But I never heard about a plant turning atmospheric N2 to nitrogen compounds.
Where nitrogen compounds come from, and from which source ? There are nitrogen fixing bacteria who turn N2 into NH3. Some are free-living in soil, others live symbiotically with plants.
https://en.wikipedia.org/wiki/Nitrogen_fixation
The following is multiple choice question (with options) to answer.
Which organisms get their energy source and carbon source from organic sources? | [
"sporozoans",
"chemoheterotrophs",
"ectomorphs",
"herbivores"
] | B | Chemoheterotrophs are organisms that get their energy source and carbon source from organic sources. Chemoheterotrophs must consume organic building blocks that they are unable to make themselves. Most get their energy from organic molecules such as sugars. This nutritional mode is very common among eukaryotes, including humans. |
SciQ | SciQ-7474 | meteorology, geology, seismology, precipitation, enso
Title: Is there any correlation between La Niña/El Niño and seismic activity? I've read in the past that extreme precipitation levels may have an effect on seismic activity, and wondered if anyone has ever analysed the La Niña / El Niño cycles to see if there is any correlation with seismic activity in the area affected by the phenomena. There is a case study from Environmental Science entitled El Niño: A Link among Atmospheric, Oceanic, and Crustal Circulation? that discusses the correlations between seismic activity and El Niño cycles in certain areas of the world, that have been documented:
A geophysicist, Daniel A. Walker, hypothesizes that a different sequence of events produces an El Niño event. Walker says that the thermal input to the oceans comes from Earth’s interior. This hypothesis is based on an intriguing correlation of seismic activity under the eastern portion of the Pacific Ocean near Easter Island and the onset of El Niño events. This correlation can be used to illustrate possible linkages among the physical systems of planet Earth and the difference between statistical correlation and physical causation.
The East Pacific Rise is located west of Easter Island. Along this rise, tectonic plates move 160–170 mm (6.3–6.7 inches) per year. This rate is one of the most rapid in the world. As a result, seismic activity along the East Pacific Rise has been studied extensively for more than thirty years. During this period scientists have tracked the number of earthquakes and the amount of energy they release.
The following is multiple choice question (with options) to answer.
What natural disaster is california most linked with? | [
"volcanoes",
"hurricanes",
"earthquakes",
"fires"
] | C | Although California is prone to many natural hazards, including volcanic eruptions at Mt. Shasta or Mt. Lassen, and landslides on coastal cliffs, the natural hazard the state is linked with is earthquakes. In this video, the boundaries between three different tectonic plates and the earthquakes that result from their interactions are explored. |
SciQ | SciQ-7475 | entomology
Title: What is the name of this tiny creature? It looks like a tiny piece of moving cotton? By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name? From your image, it looks like it might be a woolly aphid. I just did a bit of cursory research, and it looks like they're often described as floating pieces of fluff, that seem to wander instead of directly heading somewhere. The fluff on their back is actually wax produced as a defense mechanism from predators and the like. I hope this is what you were looking for!
The following is multiple choice question (with options) to answer.
Small crustaceans exchange gases across thin areas of the cuticle; larger species have what to accomplish this? | [
"gills",
"noses",
"pores",
"lungs"
] | A | |
SciQ | SciQ-7476 | anatomy, liver
The figure below is a picture of the intestinal veins from Gray's Anatomy (wikipedia) that form the hepatic portal vein, the superior and inferior mesenteric as well as the splenic vein. In the figure the older term lienal vein is used instead of splenic vein. The latin word for spleen is lineal.
The picture below is a schematic of the hepatic lobule that receives its blood from a portal triad. In the center of the lobule is the "central vein". The blood flows from the portal triad to the central vein, and then the central veins coalesce to form the hepatic veins (which then drain into the inferior vena cava). The picture below is available from this website, along with some other text and picture for more information.
And another nice picture from wikipedia on "hepatic lobules".
.
As for a "freely available review" that you asked for, I can't find any with better pictures from PubMed that what is already in this answer.
The following is multiple choice question (with options) to answer.
The superior vena cava and the inferior vena cava are veins that return blood lacking what to the heart? | [
"carbon dioxide",
"nitrogen",
"hemoglobin",
"oxygen"
] | D | The veins that return oxygen-poor blood to the heart are the superior vena cava and the inferior vena cava . The pulmonary veins return oxygen-rich blood from the lungs to the heart. The pulmonary veins are the only veins that carry oxygen-rich blood. |
SciQ | SciQ-7477 | theoretical-chemistry, intermolecular-forces, hydrogen-bond, dipole
Appendix
Optimised Structure of the adenine-thymine 2:1 complex calculated at DF-B97D3/def2-TZVPP in Gaussian 09 Rev. E.01
The following is multiple choice question (with options) to answer.
There are only four possible bases that make up each dna nucleotide: adenine, guanine, thymine, and? | [
"cytosine",
"phenylalanine",
"taurine",
"guarine"
] | A | The only difference between each nucleotide is the identity of the base. There are only four possible bases that make up each DNA nucleotide: adenine (A), guanine (G), thymine (T), and cytosine (C). |
SciQ | SciQ-7478 | physical-chemistry, kinetics, boiling-point
Title: How does the boiling point of water inside a pressure cooker change with temperature? My question is why a pressure cooker would affect the boiling point at all.
To my understanding, the boiling point of a substance is defined by 'The temperature at which the vapor pressure of the substance equals the surrounding pressure' and according to the Wikipedia article regarding pressure cooking, 'In a sealed pressure cooker, the boiling point of water increases with increasing pressure'.
Now say we fill a pressure cooker with water and turn on the heat for a while. Eventually, it'll start vaporizing and all the pressure accumulated inside the pressure cooker due to vaporization of water can be considered 'vapor pressure', but wouldn't that only mean that the vapor pressure has merely risen? Why should that affect the boiling point at all, when the 'surrounding pressure' itself is still the same? Does a change in vapor pressure also affect the boiling point in any way?
After a bit of thinking, I also started wondering if the expansion of the air inside the cooker alone was enough to increase the pressure sufficiently, but I am not really too sure about it and I couldn't find much clarity on why this pressure increase occurs otherwise. The surrounding pressure in the boiling point context is the pressure acting on the liquid, what includes also partial pressures of eventual vapors.
There is always some air in a (fully) sealed cooker and the pressure is always higher than vapor partial pressure, so boiling point is always higher than water temperature.
$$T_\mathrm{boil}=f(p_\mathrm{air}+p_\mathrm{water}(T))$$
That is obviously not true for a pressure cooker with a pressure relieve vent. With the vent, air gradually escapes when the vent relieve pressure is reached. The boiling point raises only to the temperature, at which the saturated vapor pressure equals to the vent relieve pressure.
The following is multiple choice question (with options) to answer.
What affects the boiling point of water? | [
"internal pressure",
"heat source",
"external pressure",
"latter pressure"
] | C | Boiling points are affected by external pressure. |
SciQ | SciQ-7479 | frequency, math
Title: Intuitive understanding of frequency I know that $f = \frac{\text{cycles}}{\text{unit of time}}$ and I know that period $T = \text{time it takes to complete one cycle}$.
So if we take the definition
$f = \frac{1}{T} = \frac{\text{1 cycle}}{\text{time it takes to complete one cycle}}$
So if we have some $x$ cycles we get that $f = \frac{x \text{ cycles}}{\text{time it takes to complete one cycle}}$.
How can we have $x > 1$ if it takes $T$ to complete a cycle? In other words, how could $x > 1$ have completed in the time it takes to complete one cycle?
I’m guessing that $T$ is somehow decoupled from $x$ and I’ve got my definitions mixed up. It's about units and dimensions. And I'm probably not the guy to cast an answer on that but I would like to state it as follows. In short; length, time, mass etc. are dimensions, whereas meter, seconds, kg are units of them respectively in SI. (for other dimensions and units, a physics book might help.)
Now, if a wheel rotates 7 times in 2 seconds; it's rotation frequency $f$ is found as:
$$ f = \frac{7 ~\text{ cycles}}{2 ~\text{ seconds}} = 3.5 ~\text{cycles-per-second (cps)}.$$
As can be seen, frequency is given by a (cycle) number divided by time. The cycle number has no physical units or dimensions; it's just a repetition count. Whereas the duration time has a unit of seconds (in SI).
Thus the dimesion of frequency is 1/time, whose SI unit is $1/s = s^{-1}$. This unit is also, and more frequently, denoted as Hz where it (implicitly) stands for (cycles) per second indeed. So, $3.5$ Hz stands for $3.5$ cycles per second.
The following is multiple choice question (with options) to answer.
The average length of a woman’s menstrual cycle is what? | [
"16 days",
"5 days",
"19 days",
"28 days"
] | D | The Menstrual Cycle Now that we have discussed the maturation of the cohort of tertiary follicles in the ovary, the build-up and then shedding of the endometrial lining in the uterus, and the function of the uterine tubes and vagina, we can put everything together to talk about the three phases of the menstrual cycle—the series of changes in which the uterine lining is shed, rebuilds, and prepares for implantation. The timing of the menstrual cycle starts with the first day of menses, referred to as day one of a woman’s period. Cycle length is determined by counting the days between the onset of bleeding in two subsequent cycles. Because the average length of a woman’s menstrual cycle is 28 days, this is the time period used to identify the timing of events in the cycle. However, the length of the menstrual cycle varies among women, and even in the same woman from one cycle to the next, typically from 21 to 32 days. Just as the hormones produced by the granulosa and theca cells of the ovary “drive” the follicular and luteal phases of the ovarian cycle, they also control the three distinct phases of the menstrual cycle. These are the menses phase, the proliferative phase, and the secretory phase. |
SciQ | SciQ-7480 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
Water leaves ponds and lakes through evaporation and also as what? | [
"influx",
"mid flow",
"outflow",
"inflow"
] | C | Ponds and lakes may get their water from several sources. Some falls directly into them as precipitation. Some enters as runoff and some from streams and rivers. Water leaves ponds and lakes through evaporation and also as outflow. |
SciQ | SciQ-7481 | biochemistry, proteins, amino-acids
Title: Arrangement of Amino Acids in the Protein alphabet I am a software engineer with little knowledge of molecular biology. However I am trying to understand some bioinformatics computer code where the protein alphabet appears to be represented as the following string, with each of the twenty amino acid constituents of protein:
ACDEFGHIKLMNPQRSTVWY
The code appears to define a second string in which the first is reordered as:
DEKRHNQSTPGAVILMCFYW
I am not sure of the biological significance of this. Does this reordering represent some specific interaction between these molecules? As suggested by tyersome's comment, the amino acids are grouped by their physiochemical properties. Let's add some commas:
DE,KRH,NQ,ST,PGAVIL,MC,FYW
aspartic acid (D) and glutamic acid (E) are acidic
lysine (K), arginine (R), and histidine (H) are basic
asparagine (N) and glutamine (Q) are amidic
serine (S) and threonine (T) are hydroxylic
proline (P), glycine (G), alanine (A), valine (V), isoleucine (I), and leucine (L) are aliphatic
methionine (M) and cysteine (C) are sulfur-containing
phenylalanine (F), tyrosine (Y), and tryptophan (W) are aromatic
My source is this graphic.
The following is multiple choice question (with options) to answer.
What is a biochemical compound that is a chain of amino acids called? | [
"DNA",
"lipids",
"proteins",
"hormones"
] | C | Proteins are biochemical compounds that consist of one or more chains of amino acids. Proteins have many different functions. For example, some are enzymes, and some are hormones. |
SciQ | SciQ-7482 | chromosome, gene
Title: Interpretation of picture of human chromosomes
Does this picture show sister chromatids or homologous chromosomes? If they are homologous then what is YY? If they are sister chromatids then do homologous chromosomes ever appear like this (with the centromere)? Do sister chromatids exist only in prophase-I to anaphase-I of meiosis? Since I have used more than 1 image in my answer; with numbers starting from 1; I'll call your provided figure as figure-0
What is shown in following picture?
Though the image showing many things; in overall it is an image of a set of chromosomes; seemingly almost certainly from human. The chromosomes has been stained with a banding method (though I'm not sure about which banding method used).
Are they sister chromatids?
Could not be answered in few words. The image contains sister chromatids. But the entire image in OP (fig-0) could not be described as "image of sister chromatids".
All the chromosomes in this image are in metaphase. so each chromosome is made up of 1-pair of chromatids which are sister-chromatids to each-other.
Fig 1. This total image showing 1 chromosome (on or before metaphase) showing 2 chromatids (written as A and B). A and B are sister chromatids because their DNA-content resulted from same mother-DNA molecule when replication happened at S-phase of cell-cycle; so their DNA content is basically same.
or homologous chromosome?
No. They are Not homologous. However Chromosome X and Y do have some homologous portion (Pseudo-autosomal regions). Question-figure (Fig-0) neither shows a complete set (46 chromosomes) from 1 diploid cell; nor shows its half (the haploid set) (that is causing your confusion about X and Y; let me proceed...) . Fig-0 shows each-type of human chromosome in 1 piece.
If they are homologous then what is YY?
YY karyotype does not normally exist in human.
Karyotype of human male:
2 x (22 autosome) + 1 X-chromosome + 1 Y-chromosome.
The following is multiple choice question (with options) to answer.
Each what is made of two identical sister chromatids? | [
"chromosome",
"genome",
"helix",
"gene"
] | A | Chromosomes, like those shown here, must form prior to cell division, to ensure that each daughter cell receives a complete set of genetic material. Each chromosome is made of two identical sister chromatids. Each chromatid is 1/2 of the "X. " Essentially, each daughter cell receives half of each "X-shaped" chromosome. |
SciQ | SciQ-7483 | nomenclature, history-of-chemistry, amino-acids
One can only hypothesise what they meant by "associations that might be helpful in remembering the code" in the case of N/Q/D/E. My best guess is:
D and E were possibly chosen for aspartic and glutamic acids because they were the only consecutive pair of letters left, emphasising their chemical similarity. Aspartic acid is shorter than glutamic acid by one methylene group (CH2), so it gets the earlier letter D.
Glutamine sounds like Q-tamine. If you don't think it sounds similar, repeat it 50 times until you do.
AsparagiNe was assigned N.
Reference
IUPAC-IUB Joint Commission on Biochemical Nomenclature. Nomenclature and Symbolism for Amino Acids and Peptides: Recommendations 1983. FEBS J. 1984, 138 (1), 9–37. DOI: 10.1111/j.1432-1033.1984.tb07877.x. A HTML version (perhaps more user-friendly) can be found at this address.
The following is multiple choice question (with options) to answer.
Amino groups are found within amino acids, nicknamed the building blocks of what? | [
"carbohydrates",
"protons",
"proteins",
"lipids"
] | C | Amino groups are found within amino acids, the building blocks of proteins. |
SciQ | SciQ-7484 | planet, natural-satellites, nomenclature
Title: Is the satellite of a small star in a binary solar system a moon or a planet? What exaclty distinguishes a moon from a planet?
In a binary solar system that has a large star in the center and a smaller star - among some planets - orbiting that large star, and the smaller star has natural satellites - are these satellites called moons or planets?
Or asked in a different way - if Jupiter would ignite and become a star (which it can't because its mass doesn't suffice, but let's assume it was larger and could ignite), would its moons then be considered planets? A planetary mass object (also callled a planemo) is an astronomical object large enough to be pulled into a roughly spherical shape by its gravity compressing its matter. A planetary mass object must also have less than about 13 times the mass of Jupiter or about 4,131.4 times the mass of Earth.
If a planetary mass object orbits around the Sun in our solar system it is called a planet (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, & Neptune) or a dwarf planet (Ceres, Pluto, Eris, Hamaea, and Makemake, plus of number of candidate objects).
If a planetary mass object orbits around a planet in our solar system it is considered to be a natural satellite or a moon. Smaller objects which orbit around planets are also considered to be moons.
Any object smaller than a planetary mass object that orbits the Sun in our solar system is a small solar system body. They include all comets, asteroids, etc. that orbit the Sun ddirectly instead of orbiting one of the planets, moons, asteroids etc. that orbit the sun.
Any astronomical body with a mass greater than about 75 times the mass of Jupiter, or about 23,835 times the mass of the Earth, is a star are the stellar remnant of a star which has completed its "life cycle".
Any planetary mass object which directly orbits a star which is not the Sun, in another star system, is usually considered to be planet. So far there has been no effort to classify exoplanets (planets orbiting other stars) in other star systems as planets or dwarf planets. If they are large enough to be detected they are considered to be explanets. That might possibly change sometime in the future.
The following is multiple choice question (with options) to answer.
What is the name of earth’s only natural satellite? | [
"sun",
"moon",
"titan",
"venus"
] | B | The Moon is Earth’s only natural satellite. The Moon is about one-fourth the size of Earth, 3,476 kilometers in diameter. Gravity on the Moon is only one-sixth as strong as it is on Earth. If you weigh 120 pounds on Earth, you would only weigh 20 pounds on the Moon. You can jump six times as high on the Moon as you can on Earth. The Moon makes no light of its own. Like every other body in the solar system, it only reflects light from the Sun. |
SciQ | SciQ-7485 | material-science
Title: Optimal material for a hammer head I was watching a TV show in which a gold hammer was mentioned. It was not serious but caused me to wonder whether gold would be a good material and, if not, what else might be. An attraction of gold is that it has a high density but that advantage is probably negated by being more malleable than steel. So, I started to wonder what properties I need to consider. Some materials may be hard but liable to shatter on impact.
Let's suppose that the dimensions of the hammer are fixed: a fixed handle and a fixed size and shape for the head. The objective is to drive steel nails into a variety of hard substances.
Cost is not a factor, nor ease of construction, nor safety. It will need to last long enough to be used so francium and various heavy elements are not suitable. If depleted uranium is a good material then this would be acceptable. It is used for armour piercing shells presumably because of its density but there are denser materials. Is it that it is cheaper than gold or osmium?
What properties should I be researching?
Additional: to make the question more manageable, I will require a homogenous pure material for the head not an alloy. I hope that this makes me more a question of physics rather than engineering. This is a thought experiment rather than a real project. What the optimal hammer head material is depends on what we are optimizing for.
A standard hammer has a hard head that has high density, held by a strong but usually light handle. If it has length $l$ and is accelerated at some acceleration $a$ set by user muscle strength it will reach a velocity $v$ after having traversed a distance $\sim l$; that is, $l=at^2/2$ gives $t=\sqrt{2l/a}$ and $v=\sqrt{2la}$. The kinetic energy will be $K_e\approx mla$. So a long and heavy hammer will be able to drive a nail more deeply (to a depth $K_e/F$ where $F$ is the resisting force). So more mass and length seems good... but obviously not too much either.
The following is multiple choice question (with options) to answer.
Which is the lightest of the widely used structural metals? | [
"calcium",
"Metal",
"potassium",
"magnesium"
] | D | low, the two metals with the highest ionization energies (beryllium and magnesium) do form compounds that exhibit some covalent characters. Like the alkali metals, the heavier alkaline earth metals impart color to a flame. As in the case of the alkali metals, this is part of the emission spectrum of these elements. Calcium and strontium produce shades of red, whereas barium produces a green color. Magnesium is a silver-white metal that is malleable and ductile at high temperatures. Passivation decreases the reactivity of magnesium metal. Upon exposure to air, a tightly adhering layer of magnesium oxycarbonate forms on the surface of the metal and inhibits further reaction. (The carbonate comes from the reaction of carbon dioxide in the atmosphere. ) Magnesium is the lightest of the widely used structural metals, which is why most magnesium production is for lightweight alloys. Magnesium (shown in Figure 18.6), calcium, strontium, and barium react with water and air. At room temperature, barium shows the most vigorous reaction. The products of the reaction with water are hydrogen and the metal hydroxide. The formation of hydrogen gas indicates that the heavier alkaline earth metals are better reducing agents (more easily oxidized) than is hydrogen. As expected, these metals react with both acids and nonmetals to form ionic compounds. Unlike most salts of the alkali metals, many of the common salts of the alkaline earth metals are insoluble in water because of the high lattice energies of these compounds, containing a divalent metal ion. |
SciQ | SciQ-7486 | volcanology, geomorphology
Title: Why doesn't the whole volcanic cone appear black? Cooled lava looks black, but why the whole volcano, even near crater, doesn't always appear black like cooled lava? The cooled lava might be covered by ashes. So depending of the amount of ashes and the wind you might have a black volcano or a gray volcano. Many volcanoes are formed by layers of lava and ash.
https://en.wikipedia.org/wiki/Volcano#/media/File:Volcano_scheme.svg
The following is multiple choice question (with options) to answer.
When lava flows over a large area and cools, it creates a large, flat surface of what type of rock? | [
"metamorphic",
"tidal",
"igneous",
"sedimentary"
] | C | A lava plateau is made of a large amount of fluid lava. The lava flows over a large area and cools. This creates a large, flat surface of igneous rock. Lava plateaus may be huge. The Columbia Plateau covers over 161,000 square kilometers (63,000 square miles). It makes up parts of the states of Washington, Oregon, and Idaho. |
SciQ | SciQ-7487 | 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.
Examples of what process are evident in many biological systems because cells are surrounded by semipermeable membranes? | [
"osmosis",
"photosynthesis",
"apoptosis",
"reproduction"
] | A | Examples of osmosis are evident in many biological systems because cells are surrounded by semipermeable membranes. Carrots and celery that have become limp because they have lost water can be made crisp again by placing them in water. Water moves into the carrot or celery cells by osmosis. A cucumber placed in a concentrated salt solution loses water by osmosis and absorbs some salt to become a pickle. Osmosis can also affect animal cells. Solute concentrations are particularly important when solutions are injected into the body. Solutes in body cell fluids and blood serum give these solutions an osmotic pressure of approximately 7.7 atm. Solutions injected into the body must have the same osmotic pressure as blood serum; that is, they should be isotonic with blood serum. If a less concentrated solution, a hypotonic solution, is injected in sufficient quantity to dilute the blood serum, water from the diluted serum passes into the blood cells by osmosis, causing the cells to expand and rupture. This process is called hemolysis. When a more concentrated solution, a hypertonic solution, is injected, the cells lose water to the more concentrated solution, shrivel, and possibly die in a process called crenation. These effects are illustrated in Figure 11.28. |
SciQ | SciQ-7488 | ichthyology, vertebrates
Title: If an organism is supported only by cartilage, does it have an endoskeleton? Lamprey and sharks lack bones, but does this mean they are not classified as having an endoskelton? Does an organism need bone to be considered as having an endoskeleton? From wikipedia
An endoskeleton (From Greek ἔνδον, éndon = "within", "inner" + σκελετός, skeletos = "skeleton") is an internal support structure of an animal, composed of mineralized tissue.
Cartilage is a mineralized tissue so it counts as a skeleton from this definition. A bit further in the wikipedia article it says
The vertebrate endoskeleton is basically made up of two types of tissues (bone and cartilage)
The following is multiple choice question (with options) to answer.
What does cartilage lack compared to bones, making it softer and less rigid? | [
"magnesium",
"potassium",
"protein",
"calcium"
] | D | Skeletons made of cartilage rather than bone. Cartilage is supportive tissue that does not have as much calcium as bones, which makes bones rigid. Cartilage is softer and more flexible than bone. |
SciQ | SciQ-7489 | everyday-chemistry, water, crystallography
Spin-off question:
I heard (not sure where) that each snowflake assumes a unique shape. How true is this?
Now, as I understand it, all processes proceed so as to maximize the "randomness" of its constituent particles. (Oversimplified version of the Second Law of Thermodynamics, yes, I know... just don't chew me out in the comments section...)
Yes. True.
This Law can easily be observed in, and verified by, natural processes.
Sure. Still with you.
Now the formation of snow is a natural process, agreed? The way my brain sees it, is that water droplets ought to freeze into random, and by virtue of its "randomness", highly unsymmetrical shapes. But this is not the case here!
The following is multiple choice question (with options) to answer.
What three forms does frozen precipitation take? | [
"vapor, fog, ice",
"hail, wind, typhoon",
"snow, sleet, freezing rain",
"blizzard, frost, fog"
] | C | Frozen precipitation may fall as snow, sleet, or freezing rain. |
SciQ | SciQ-7490 | fluid-dynamics, simulations, oceanography
Title: Ocean surface mean current flow meaning I tried to simulate the trajectory of an drifting object in the oceans by using the data of the OSCAR project http://www.oscar.noaa.gov/. The dataset actually used consist of grid sampled mean 2d current vectors averaged on a monthly interval indicating the speed and direction of water near the sea surface.
However, moving an object by the gradients shows that the gradient field is riddled with attractors and repellors. There may be several reasons for this, like the water flowing vertically or the mean operation introducing artifacts.
Thus moving an object along trajectories made up by a static snapshot of the dataset isn't very useful, as it usually get stuck in one of the hundreds of sink attractors. This contradicts the usual knowledge of drifting particles to accumulate in very large vortices and eventually reach almost every coastal point on earth.
So how should the mean current be interpreted in respect to drifting object movement? Is there a simple solution to get a coarse drifting simulation that qualitative resembles the expected behavior ? I believe these attractors you are referring to are generally referred to as eddies in the ocean. These features are similar to the hurricanes, and low and high pressure systems in the atmosphere, and just like in the atmosphere they move around.
With monthly mean data (monthly climatology) you can advect particles around in a variety of different ways. The simplest way might be to do a linear interpolation in time between the months and then using that as a time series of velocities. Advecting particles using a single time snap shot of the velocity is not very realistic as the advection of drifters in the real ocean is due to both the velocities and the patterns that these velocities change in. Also by using the monthly mean velocity with linear interpolation you lose the effects of shorter than one month velocity variabilities effect, that have not been sampled by the data.
Quite often the effect of unresolved motions (both in time or space) in the ocean are assumed to be diffusive and you will be able to find a lot of literature on how to parameterize it using some assumptions.
It might be better to post what your ultimate goal is for the trajectory advection experiments and one route over another might be more useful.
The following is multiple choice question (with options) to answer.
What is a stream of moving water that flows through the ocean? | [
"waterfall",
"tidal wave",
"creek",
"current"
] | D | Another way ocean water moves is in currents. A current is a stream of moving water that flows through the ocean. Surface currents are caused mainly by winds, but not the winds that blow and change each day. Surface currents are caused by the major wind belts that blow in the same direction all the time. |
SciQ | SciQ-7491 | human-anatomy, muscles
Title: Contracting muscles in humans I study biology at school, and unfortunately for me, my program skips the muscles in humans chapter.
I know (and mainly, feel) that the movement in one direction isn't created by the same muscle as the movement in the opposite direction, e.g the Triceps ("front") and Biceps ("back").
I know that the triceps straightens the elbow, while the biceps contracts the elbow.
I also know that, instead of actually moving the arm, I can contract these two muscles (when I show off, for example...) without actually moving the arm. That area becomes hard. Both muscles, as I feel, are contracting. I cannot statically contract only one of them.
My question is whether this action is something "special", or simply both muscles working against each other, resulting in zero movement? The situation you are describing where muscles are situated on opposites sides of a joint and produce opposing movements is called "antagonism." Most joints are set up where one or more muscles on either sides will produce such movements (e.g., flexors vs. extensors). Here's a question about muscles without antagonists.
When you contract all the muscles crossing a joint (i.e., when you are "showing off"), the muscles balance each other. If not, the bones would move and the joint angles would change. So taking the elbow as an example, in the image below, Arnold is contracting the elbow flexors (biceps brachii, brachialis) as well as the elbow extensors (triceps brachii). In order for the bones to remain static, the forces must be equal and opposite.
The following is multiple choice question (with options) to answer.
The elbow is an example of a what type of joint? | [
"hinge joint",
"pipe joint",
"toe joint",
"frame joint"
] | A | Hinge Joints In hinge joints, the slightly rounded end of one bone fits into the slightly hollow end of the other bone. In this way, one bone moves while the other remains stationary, like the hinge of a door. The elbow is an example of a hinge joint. The knee is sometimes classified as a modified hinge joint (Figure 38.28). |
SciQ | SciQ-7492 | species-identification, botany
Weakley (2015) "Flora of the Southern and Mid-Atlantic States"
1 Leaflets 3, toothed, lobed, or entire; shrub or vine.
2 Fruits pubescent or papillose; leaflets entire, coarsely toothed, undulate, or round-lobed; lower surfaces of leaflets either velvety puberulent, sometimes becoming glabrate in age (T. pubescens) or glabrous (glabrescent or rarely pilose beneath) but with prominent tufts of tannish hairs present in the vein axils (T. radicans var. radicans).
3 Leaves sparsely pubescent (rarely pilose beneath), the apex and the lobes (if present) generally acute to acuminate; drupes papillose, scabrous or puberulent; plant a high-climbing vine or stoloniferous shrub; [of mesic, swampy, or dry habitats].......... T. radicans var. radicans
3 Leaves velvety puberulent (sometimes becoming glabrate in age), the apex and the lobes (if present) generally obtuse to broadly acute; drupes pubescent (becoming glabrate); plant a stoloniferous shrub; [of dry habitats, especially sandhills] ............. T. pubescens
2 Fruits glabrous (or very sparsely pubescent); leaflets coarsely toothed or notched (rarely entire); lower surfaces of leaflets glabrous to pubescent, but without tufts of tannish hairs in the vein axils.
The following is multiple choice question (with options) to answer.
The first leaves of most ferns appear curled up into what? | [
"volatiles",
"nanotubes",
"fiddleheads",
"petals"
] | C | The first leaves of most ferns appear curled up into fiddleheads. |
SciQ | SciQ-7493 | organic-chemistry, acid-base, reactivity
In a polar aprotic solvent, however, where there are no positively polarized hydrogens for a nucleophile to hook onto; $\ce{F^-}$ becomes a much stronger nucleophile. Actually, $\ce{F^-}$ becomes a better nucleophile than $\ce{I^-}$, likely due to $\ce{F^-}$'s greater charge density.
The following is multiple choice question (with options) to answer.
Electrophiles have a strong tendency to react with what? | [
"resistors",
"neutrons",
"acids",
"nucleophiles"
] | D | Electrophiles have a strong tendency to react with nucleophiles. CONCEPTUAL PROBLEMS. |
SciQ | SciQ-7494 | heat, friction, everyday-life
Title: How hot does the tip of a pencil get while writing? When writing with a pencil, there seems to be quite a lot of friction - which seems like it would induce heat.
How hot would the tip of a #2 pencil get writing on normal copy paper? Graphite (pencil "lead") is an allotrope of carbon that occurs in layers of carbons arranged into hexagons, tessellating the plane. Each carbon is $sp^2$ bonded and each layer is one atom thick. The bonds holding the carbons in one plane together are incredibly strong, uniform covalent bonds of strength ~1.33, and the carbons are in a very stable hexagonal arrangement. These bonds are incredibly difficult to break, hence graphite's extraordinarily high melting point (several thousand kelvins).
By contrast, there are only weak dispersion forces holding different planes together, which are easily broken. When you write, you are breaking these bonds to leave graphite layers on the paper.
Imagine a deck of cards. Even if you're the fastest dealer in the world, the deck never heats up. Why? Because however much friction is felt at the interface between the top card and the one under it, it is only felt for a moment and then new, cool cards feel it.
The following is multiple choice question (with options) to answer.
What layered form of carbon is used as a lubricant and in pencils? | [
"lead",
"graphite",
"carbonite",
"copper"
] | B | Graphite is a form of carbon in which carbon atoms are arranged in layers. Bonds are strong between carbon atoms within each layer but relatively weak between atoms in different layers. The weak bonds between layers allow the layers to slide over one another. This makes graphite relatively soft and slippery. It is used as a lubricant. It also makes up the "lead" in pencils. |
SciQ | SciQ-7495 | elementary-particles
A textbook on solid state physics can help elucidate further properties of solids for you.
A textbook on the Standard Model of particle physics would be useful to catalog the known point-particles like electrons, muons, gluons, etc.
Finally, you mentioned "elements". By this, I believe you mean the different types of atoms, e.g., the element hydrogen, the element copper, etc. The different elemental atoms have different properties due to their differing number of protons, e.g. hydrogen has 1 proton, copper has 29 protons. In this matter, too, a textbook on chemistry will be useful to you.
Cheers.
The following is multiple choice question (with options) to answer.
What kind of solids have particles that are arranged in a regular repeating pattern? | [
"salts",
"carbon-based solids",
"metabolic solids",
"crystalline solids"
] | D | Crystalline solids have particles that are arranged in a regular repeating pattern. They form crystals. Amorphous solids have particles that are arranged more-or-less at random. They do not form crystals. |
SciQ | SciQ-7496 | physiology, cell-biology
Title: Polarized epithelium and localization of ion channels I'm trying to learn more about polarized epithelial cells of the gut. I am familiar with classic brush border transporters localized to the apical memebrane to facilitate nutrient absorption. I am wondering though, where are ion channels located? I would guess basolaterally since they would be exposed to the extracellular space. I would appreciate a primary reference showing the location of voltage-gated channels in particular as I could not find them myself. Well, that's a first for me. I wouldn't have guessed gut cells would have voltage-gated channels.
This article describes voltage-gated sodium channels on both the luminal and basolateral membranes:
Barshack, I., Levite, M., Lang, A., Fudim, E., Picard, O., Ben Horin, S., & Chowers, Y. (2008). Functional voltage-gated sodium channels are expressed in human intestinal epithelial cells. Digestion, 77(2), 108-117.
http://www.ncbi.nlm.nih.gov/pubmed/18391489
The following is multiple choice question (with options) to answer.
During what in the small intestine do rings of smooth muscle repeatedly contract and then relax? | [
"segmentation",
"mitosis",
"compression",
"contraction"
] | A | Mechanical Digestion in the Small Intestine The movement of intestinal smooth muscles includes both segmentation and a form of peristalsis called migrating motility complexes. The kind of peristaltic mixing waves seen in the stomach are not observed here. If you could see into the small intestine when it was going through segmentation, it would look as if the contents were being shoved incrementally back and forth, as the rings of smooth muscle repeatedly contract and then relax. Segmentation in the small intestine does not force chyme through the tract. Instead, it combines the chyme with digestive juices and pushes food particles against the mucosa to be absorbed. The duodenum is where the most rapid segmentation occurs, at a rate of about 12 times per minute. In the ileum, segmentations are only about eight times per minute (Figure 23.20). |
SciQ | SciQ-7497 | zoology, metabolism, fat-metabolism
Acetyl CoA can then serve as a substrate for citrate synthesis. Citrate, in turn, can be transported out of the mitochondria to the cytoplasm. There it can be split to generate cytoplasmic acetyl-CoA for fatty acid synthesis under the influence of anabolic factors like insulin in times of plenty (Fig. 3), referred to as lipogenesis.
The following is multiple choice question (with options) to answer.
Acetyl-coa is formed from the breakdown of carbohydrates, lipids, and what else? | [
"acids",
"hydrocarbons",
"proteins",
"hormones"
] | C | Acetyl-CoA is formed from the breakdown of carbohydrates, lipids, and proteins. It is used in many biochemical pathways. |
SciQ | SciQ-7498 | biochemistry, endocrinology, cell-signaling
Title: Effect of steroid hormone on specific cells? As steroid hormones can pass through the plasma membrane by simple diffusion because they are lipid derived hormones, it means that they are capable of passing through every cell of our body, BUT why are only specific cells responsive against steroid hormones?
For example, all of our body cells almost contains the genes for the development of secondary sexual characters but why do only specific cells show a response against these steroid hormones because the development of secondary sexual characters occur only in specific region of our body, that is, beard formation occur only in a specific region of the face, etc.
IN SUMMARY: When steroid hormones can pass through every cell of our body then why do they show only a localized response? Unlike other types of hormones, steroid hormones do not have to bind to plasma membrane receptors. Instead, they can interact with intracellular receptors that are themselves transcription activators. Steroid hormones too hydrophobic to dissolve readily in the blood travel on specific carrier proteins from their point of release to their target tissues. In the target tissue, the hormone passes through the plasma membrane by simple diffusion and binds to its specific receptor protein in the cytoplasm. The receptor-hormone complex then translocates into the nucleus where it acts by binding to highly specific DNA sequences called hormone response elements (HREs), thereby altering gene expression.
Hormone binding triggers changes in the conformation of the receptor proteins so that they be- come capable of interacting with additional transcription factors. The bound hormone-receptor complex can either enhance or suppress the expression of adjacent genes.
The DNA sequences (HREs) to which hormone- receptor complexes bind are similar in length and arrangement, but differ in sequence, for the various steroid hormones. Each receptor has a consensus HRE sequence to which the hormone-receptor complex binds well, with each consensus consisting of two six-nucleotide sequences, either contiguous or separated by three nucleotides,
The ability of a given hormone to act through the hormone-receptor complex to alter the expression of a specific gene depends on the exact sequence of the HRE, its position relative to the gene, and the number of HREs associated with the gene.
The following is multiple choice question (with options) to answer.
Juvenile hormone modulates the activity of what? | [
"ecdysteroid",
"growth",
"estrogen",
"reproduction"
] | A | |
SciQ | SciQ-7499 | geology, soil, mapping, regional-geology
Title: What is the average color of soil? Where I live the soil is red.
Is there a map or chart where you can see the average color of the dirt according to geographical location? What would the color be if all of the dirt on Earth was added equally to a pallet?
I understand that composition of minerals determines dirt color but what makes dirt its color is not the question I am asking.
Kata Tjuta, Northern Territory, Australia
Sagada, Mountain Province, Philippines
https://eugeneexplorer.wordpress.com/2016/11/22/blue-soil-hills/
Gentry County, Missouri, United States
http://www.airphotona.com/image.asp?imageid=11944 This gif, prepared by the United States Department of Agriculture - Natural Resources Conservation Services (USDA-NRCS) soil scientists at the National Soil Survey Center, has soil colors based on the Munsell Color System for the United States at different depths:
The soil colors nearest the surface are darker due to more organic matter and are lighter at depth with varying colors by region.
Source: http://munsell.com/color-blog/soil-colors-national-parks-anniversary/
This link also has soil colors of select United States National Parks. For example:
The following is multiple choice question (with options) to answer.
What causes the red color of laterite soils? | [
"erosion",
"iron oxides",
"toxins",
"oxygen"
] | B | A third important type of soil is laterite . Laterite forms in tropical areas. Temperatures are warm and rain falls every day ( Figure below ). So much rain falls that chemical weathering is intense. All soluble minerals are washed from the soil. Plant nutrients get carried away. There is practically no humus. Laterite soils are often red in color from the iron oxides. If laterites are exposed to the Sun, they bake as hard as a brick. |
SciQ | SciQ-7500 | geography, cartography
Title: Is there a name for the process of producing positional data for cartography? Map-making requires two distinct processes, first to produce the data -- latitude, longitude and elevation -- of the points to be mapped; and second to represent this data on a flat surface as a map.
Cartography nicely covers the science of creating the map from the data -- plotting points to give an accurate representation of desired properties, realising that at least one of shape, area, direction or distance, has to be sacrificed.
Is there an overall name for the initial gathering of data? Terms like "surveying" seem to me to be too specialised or limited to cover all the processes involved, and "topography" seems too broad. Thank you @Fred. Surveying and Topography do cover it but they both have wider meanings than the restricted use I am after.
Topometry is the closest official word I have found. Here is the definition from the Wiktionary:
Noun
topometry (uncountable)
(chiefly medicine) Any of various imaging or surveying techniques in which the three-dimensional positions of an array of points is
recorded.
The combinatiom of "topo" for shape and "metry" for measurement seems to cover it nicely.
So, adding "geo" for the earth, I would like to coin the word Geotopometry to express the exact meaning I am after, although my spell checker doesn't like it, and probably not many people will know what I mean when I use it.
The following is multiple choice question (with options) to answer.
The scientific process of collecting data outside the lab (in the "wild") is known as what kind of work? | [
"track work",
"field work",
"experimentation",
"scientific investigation"
] | B | Many Earth scientists collect data in the field, called field work . The data may be from observations or measurements. The scientists may create a geological map of the area. They might write detailed descriptions of the rocks and their relationships. They may collect samples to analyze in the lab. They may do a combination of all of these! Earth science laboratories contain high-tech equipment. That equipment can reveal the chemistry or age of a rock sample. Geologists do field work to look for resources. They may study a region for environmental cleanup. There are many other reasons for going in the field. One common reason is just to understand the region better. |
SciQ | SciQ-7501 | immunology, lab-techniques, flow-cytometry, cell-sorting
Without lysis, the RBCs overwhelm the cytometer, as they make up around 95% of the cells in human whole blood. White blood cells (leukocytes), on the other hand, only make up 0.1-0.2% of cells, and lymphocytes between about 15 to 50% of leukocytes.
The cell mixture is then analyzed on a cell sorter such as a BD FACSAria.
From: https://commons.wikimedia.org/wiki/File:Fluorescence_Assisted_Cell_Sorting_%28FACS%29_B.jpg
The cells pass in single file past one or more laser beams, which excite the dyes and cause them to fluoresce at a certain wavelength. The user can then use gating to select the combination and intensity of colors they are interested in, and when a cell meets the criteria, it is given an electrical charge, and electro magnets direct it into a collection container.
The following is multiple choice question (with options) to answer.
Red blood cells, white blood cells, platelets, and plasma are all components of what fluid? | [
"heart",
"Vessals",
"blood",
"brain"
] | C | 40.2 Components of the Blood Specific components of the blood include red blood cells, white blood cells, platelets, and the plasma, which contains coagulation factors and serum. Blood is important for regulation of the body’s pH, temperature, osmotic pressure, the circulation of nutrients and removal of waste, the distribution of hormones from endocrine glands, and the elimination of excess heat; it also contains components for blood clotting. Red blood cells are specialized cells that contain hemoglobin and circulate through the body delivering oxygen to cells. White blood cells are involved in the immune response to identify and target invading bacteria, viruses, and other foreign organisms; they also recycle waste components, such as old red blood cells. Platelets and blood clotting factors cause the change of the soluble protein fibrinogen to the insoluble protein fibrin at a wound site forming a plug. Plasma consists of 90 percent water along with various substances, such as coagulation factors and antibodies. The serum is the plasma component of the blood without the coagulation factors. |
SciQ | SciQ-7502 | phylogenetics, trees, visualization
An interesting - and new to me - point of view is given in Joseph Ahrens' answer to this Quora question:
How do you interpret ancestry in phylogenetic trees?
What slowly becomes clear to me: It's about the interpretation of straight line segments, maximal straight lines, of horizontal vs. vertical lines, and nodes (= branching points) in phylogenetic trees, especially: which of them is to interpreted as a species? Here's the issues with your well considered project:
1/ Temporal datasets to proportion trees: That's probably the most absent thing in species measurement. You'd need data sets of time for beetle species, for mammals, plants in millenia and million years. 90+% of that information is absent.
2/ Genetic proximity to arrange trees. Scientists publish their genome studies into the ToL project. There is lots of distance data to compare all animals.... Genetic distance doesn't graph easily because on the same tree, some distances can be 500 times longer than others. On a tree of 20 extant species, you will have branches 5mm long and 5 meters long, half the the species are on your screen and the other half are higher than the ceiling. It's best to represent them with another symbol, else interactive 3D trees where you can switch compact/large views and the tree zooms out crazily, it's illustrative and cool, else use a weighted proximity length which is 1+ similarity/50, that doesn't really work either. either way, I couldnt find a way of clearly displaying that info on the tree.
Phylogeny trees don't lend themselves well to being informatively measured. You start by thinking "Oh I could find a pretty way of doing that" then when you apply the datasets, your trees become uncontrollable and jumbled up because of exponential branch lengths.
I programmed phylogenetic trees based on the 81MB ToL tree of life project to represent many millions of species, to do 3D physics trees and HTTP lookups to provide wiki texts and images for all species. There is www.biostars.org a very kind and helpful bioinformatics forum for postgrads that do trees all day.
There are many (dozens) of informative tree graphics programs coded by academics, to visualizw and analyzw species data, arranged into different trees and sorting through them.
The following is multiple choice question (with options) to answer.
Who created the idea of an evolutionary tree to represent the relationships between different species and their common ancestors? | [
"Isaac Newton",
"charles darwin",
"Scopes",
"Carl Sagan"
] | B | If evolution can take a very long time, how can we visualize how it happens? Charles Darwin came up with the idea of an evolutionary tree to represent the relationships between different species and their common ancestors ( Figure below ). The base of the tree represents the ancient ancestors of all life. The separation into large branches shows where these original species evolved into new species. |
SciQ | SciQ-7503 | botany
Title: Do plants absorb toxins from the soil? Consider a plant like Aloe Vera that grows up in a toxic environment where the concentration of pesticides, and materials like lead, mercury, cadmium, arsenic etc is very high(e.g. Marshland dumping yard ). Would that mean that the extract from these plants would contain all these toxic elements. Not "all of them". But yes, plants suck up water from the soil, with everything dissolved in this water - nutrients, heavy metals, poisons. And also they breathe air, and absorb stuff via this route.
There probably are some toxins which will not enter the plant, because their molecules are too large and/or fragile. For example, should a plant root come in contact with snake venom, I cannot imagine that any venom will end up stored in the plant leaves.
Plants also have their own metabolism, so they will change/deactivate some toxins. I've seen claims that some plants "purify" formaldehyde, although I don't trust the sources enough to be sure of that.
But the smaller the poison molecule, and the less similar to stuff which is usually digested in nature, the more likely that it will enter the plant and stick around instead of being broken down. The heavy metals you mentioned are prime candidates. If they are present in the groundwater - or also lead from air pollution, before we banned leaded gasoline - they end up in plants, including food plants. And mushrooms are even more at risk.
Growing food near waste dumps is a known problem in farming, and sometimes makes the news, for example here:
http://bigstory.ap.org/article/mafia-toxic-waste-dumping-poisons-italy-farmlands
The following is multiple choice question (with options) to answer.
What organs absorb water and nutrients from the soil? | [
"roots",
"leaves",
"flowers",
"buds"
] | A | |
SciQ | SciQ-7504 | geology, volcanology, mineralogy, minerals
Title: Where can obsidian be found? Where is obsidian found?
Is it typically found on the surface or underground?
If underground, how far under (meters or feet would be perfect)?
Also, is it found everywhere on Earth, or just in areas where volcanic activity is (or was recently) high? Obsidian is formed when a rhyolitic (or felsic) lava flows cool rapidly. This must mean that it's mostly available on the surface (and I think if you go near volcanos you can find pieces of Obsidian on the ground) because molten rock cools much faster above ground than it does below, allowing the melt to cool with small crystals (as opposed to intrusive rocks which have larger crystals). This means that Obsidian is an extrusive igneous rock.
I am betting that Obsidian is very common around most active volcanos around the world!
The following is multiple choice question (with options) to answer.
What does magma that cools underground form? | [
"fluctuations",
"instrusions",
"chambers",
"new crust"
] | B | Magma that cools underground forms intrusions ( Figure below ). Intrusions become land formations if they are exposed at the surface by erosion. |
SciQ | SciQ-7505 | meteorology, severe-weather
More than anywhere but northern California.
And another ISU page allows it to be shown that:
... Most spots in northern Idaho only see about one severe thunderstorm warning per year on average (versus 10-20 per year over Oklahoma).
So the danger of severe convective weather is remarkably low in that region of the country overall.
The following is multiple choice question (with options) to answer.
Which season is moist, causing the most thunderstorms? | [
"summer",
"winter",
"autumn",
"spring"
] | A | |
SciQ | SciQ-7506 | endocrinology, glucose, homeostasis, insulin, hypothalamus
Title: Role of the Hypothalmus in the control of Blood Sugar In homeostatic regulation of blood glucose, the receptor and effector is the Pancreas, but how does the control centre — the Hypothalamus — connect and link into this process? Your question doesn’t make it clear whether you think that the pancreas must be under the control of the hypothalmus, or whether you are asking whether it has an influence on the pancreas in relation to the secretion of insulin and glucagon, which control the concentration of blood glucose.
First, it has been long known that secretion of insulin can be influenced by the concentration of glucose in isolated pancreatic islets in vitro, so it can not be true that the effects must involve the hypothalmus. This is implicit in most book or general information articles you might find on the web, but for an original reference a review by W.J. Malaisse in Diabetologia 9, 167–173 (1973) seems highly cited.
I know almost nothing about physiology, but on searching the web for the role of the hypothalmus in glucose homeostasis, found a most readable prize-winning postgraduate essay on the topic by Syed Hussein of Imperial College London. I trust that it is in order to append an edited extract of this:
The following is multiple choice question (with options) to answer.
What are the two hormones primarily responsible for maintaining homeostasis of blood glucose levels? | [
"dopamine and melanin",
"insulin and glucagon",
"anabolic and metabolic",
"insulin and estrogen"
] | B | Hormonal Regulation of Metabolism Blood glucose levels vary widely over the course of a day as periods of food consumption alternate with periods of fasting. Insulin and glucagon are the two hormones primarily responsible for maintaining homeostasis of blood glucose levels. Additional regulation is mediated by the thyroid hormones. |
SciQ | SciQ-7507 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
What important process takes place in specialized tissue inside plant leaves? | [
"pollination",
"mitosis",
"photosynthesis",
"reproduction"
] | C | specialized tissue inside plant leaves where photosynthesis takes place. |
SciQ | SciQ-7508 | evolution, trees
Title: How related are trees? I was surprised to see how far apart macadamia and hazelnuts are from each other. I always thought all trees had a common ancestor that was also a tree. But that doesn't seem to be the case? Did wood evolve multiple times? The word "tree" is a not a taxonomic classification, but a human perceptual clustering based on form and size. The word "fish" has a similar problem, covering a vast collection of taxa, some of which are less closely related to one another than they are to us.
Becoming tree-like often has a strong evolutionary value, because plants compete for sunlight and taller plants shade shorter plants. Thus, we should not be surprised that "tree" forms have evolved independently in a number of different lineages.
The common evolutionary lineage for all of these, however, is tracheophyta, the vascular plants. These are plants that have differentiated xylem (which is the wood of a tree) and phloem tissues for transport of water and minerals. Most such plants are not trees, of course, but these tissues provide an effective means of vertical transport and the basis for hard woody material, which appears to have been the key differentiator between plants capable of evolving into trees and plants that are not able do to so.
The following is multiple choice question (with options) to answer.
What type of plants were the first to evolve? | [
"nonvascular",
"cocklebur",
"kilocalorie",
"vascular"
] | A | Nonvascular plants were the first plants to evolve. Compared to other plants, their small size and lack of specialized structures, such as vascular tissue, stems, leaves, or flowers, explains why these plants evolved first. The first nonvascular plants to evolve were the liverworts. The hornworts evolved somewhat later, and mosses apparently evolved last. Of all the bryophytes, mosses are most similar to vascular plants. Presumably, they share the most recent common ancestor with vascular plants. |
SciQ | SciQ-7509 | 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.
In multicellular organisms, specialized cells may be organized into what, which in turn may be organized into organs? | [
"blood cells",
"muscles",
"tissues",
"nutrients"
] | C | In multicellular organisms, specialized cells may be organized into tissues. Tissues may be organized into organs, and organs may be organized into organ systems. Organ systems work together to carry out all the functions of the whole organism. |
SciQ | SciQ-7510 | human-physiology, digestion, stomach
The stomach accomplishes much of its function by mechanically breaking down the swallowed food particles and mixing them with acid and enzymes into a sort of slurry. To do this, there are three major layers of muscle surround the stomach - from the outside, the longitudinal layer, the circular layer, and the oblique layer. The stomach also has two holes in it - the gastroesophageal opening, coming from the esophagus with the swallowed food/saliva mix, and the pylorus, where the food/acid/enzyme slurry exits into the duodenum, which is the beginning of the small intestine.
Due to the three layers of (rather strong) muscle, the stomach doesn't have a lot of expansion capability once it is filled completely to capacity. Fortunately, this almost never occurs (despite how we may feel after a large meal) because material is always leaving the stomach on its way to enzymatic digestion in the intestines. Additionally, once the stomach is filled to a certain extent, hormones such as leptin are secreted that give you the feeling of being sated, or full, triggering the brain to make you stop eating.
Of course, as we can see with the current epidemic of obesity around the world, the stomach can change its size over time. However, this is a rather slow process (weeks to months to years) of adapting to continuously consuming large meals.
But what would happen if you completely ignored these internal warnings, or were being force-fed, or whatever? Instead of rupturing (the biological equivalent of "exploding"), food would most likely be expelled either into the small intestine or back into the esophagus and back up the way it came down, i.e. causing vomiting.
The following is multiple choice question (with options) to answer.
What are accessory digestive organs critical for breaking down? | [
"food",
"enzymes",
"hormones",
"pathogens"
] | A | Digestive System Organs The easiest way to understand the digestive system is to divide its organs into two main categories. The first group is the organs that make up the alimentary canal. Accessory digestive organs comprise the second group and are critical for orchestrating the breakdown of food and the assimilation of its nutrients into the body. Accessory digestive organs, despite their name, are critical to the function of the digestive system. |
SciQ | SciQ-7511 | meteorology, geophysics, wind
Title: Why does the wind periodically change direction?
Image Subtitle: Wind going across the page - and changing direction
To clarify, imagine you were sat in a boat in the middle of a lake recording the wind direction every minute. You notice that the wind changes direction roughly every five minutes from 340° to 360° and back and forth...
On other days the time between and the amount (°) of wind shift can be bigger or smaller.
I presume it is something to do with the wind going over land:
It is known that the wind is directionally deflected over land (frictional effects)
Wind higher up in the atmosphere is less hindered and so less deflected
My guess is that the wind experienced on the lake is an alternation between these though the exact mechanics of it is beyond me. I would greatly appreciate a true explanation. For the answer to why there is wind, see: Where does wind come from?
That establishes the forces at work driving the wind, namely:
non-linear advection of momentum
the pressure gradient force (PGF)
the Coriolis force
friction
Friction is less over water than over land, and so the wind will tend to flow more parallel to the isobars than they will over land at the earths surface. The force balance between the PGF, Coriolis and friction is easy to conceptualize:
Image taken from University of Illinois at Urbana-Champaign, credits at http://ww2010.atmos.uiuc.edu/(Gh)/abt/aknw/dvlp.rxml
In this we can see that see that wind will flow with low pressure to its left, and cross the isobars slightly toward the low pressure. The angle of the wind crossing the isobars is related to friction. The direction of the wind is related to the orientation of the isobars and friction. The speed of the wind is related to the spacing between isobars (close = fast, far = slow).
However, this only explains a steady-state wind in equilibrium, which is great for theoretical explanations but is too idealized for the real atmosphere. In your observations on the lake, the flow is not steady-state and that pesky non-linear term is at work.
The following is multiple choice question (with options) to answer.
The direction of prevailing winds determines the type of what that usually moves over an area? | [
"water mass",
"storm",
"air mass",
"weather"
] | C | The direction of prevailing winds determines which type of air mass usually moves over an area. For example, a west wind might bring warm moist air from over an ocean. An east wind might bring cold dry air from over a mountain range. Which wind prevails has a big effect on the climate. What if the prevailing winds are westerlies? The westerlies blow from nearer the Equator to farther from the Equator. How would they affect the climate?. |
SciQ | SciQ-7512 | h. Evaluate C.
i. Compute Q(7), the amount of glucose produced during the day.
Exercise 10.3.5 “Based on studies using isolated animal pancreas preparations
maintained in vitro, it has been determined that insulin is secreted in a biphasic manner in response to a marked increase in blood glucose. There is an initial burst of insulin secretion that may last 5-15 minutes, a result of secretion of preformed insulin secretory granules. This is followed by more gradual and sustained insulin secretion that results largely from biosynthesis of new insulin molecules. ” (Rhoades and Tanner, P 710)
a. A student eats a candy bar at 10:20 am. Draw a graph representative of the rate of insulin secretion between 10:00 and 11:00 am.
b. Draw a graph representative of the amount of serum insulin between 10:00 and 11:00. Assume that insulin is degraded throughout 10 to 11 am at a rate equal to insulin production before the candy is eaten, and that serum insulin at 10:00 was Iq.
CHAPTER 10. THE FUNDAMENTAL THEOREM OF CALCULUS
468
c. Write an expression for the amount of serum insulin, I(t), for t between 10:00 and 11:00 am.
Exercise 10.3.6 Equal quantities of gaseous hydrogen and iodine are mixed resulting in the reaction
which runs until I 2 is exhausted [H 2 is also exhausted). The rate at which I 2 disappears is ^°’^ 2 gm/sec. How much I 2 was initially introduced into the mixture?
a. Sketch the graph of the reaction rate, r(t) = jp^yi-
b. Approximately how much I 2 combined with H 2 during the first second?
c. Approximately how much I 2 combined with H 2 during the second second?
d. Let Q(x) be the amount of I 2 that combines with H 2 during time 0 to 2; seconds. Write an integral that is Q(x).
e. What is Q\x)l
f. Compute W'{x) for W(x) = =^.
g. Show that there is a number, C, for which Q(x) = W(x) + C.
h. Show that C = 0.2 so that Q(x) = 0.2 – g.
The following is multiple choice question (with options) to answer.
As blood glucose levels rise what is released from the pancreas? | [
"adrenaline",
"insulin",
"hemoglobin",
"estrogen"
] | B | 24.5 Metabolic States of the Body There are three main metabolic states of the body: absorptive (fed), postabsorptive (fasting), and starvation. During any given day, your metabolism switches between absorptive and postabsorptive states. Starvation states happen very rarely in generally well-nourished individuals. When the body is fed, glucose, fats, and proteins are absorbed across the intestinal membrane and enter the bloodstream and lymphatic system to be used immediately for fuel. Any excess is stored for later fasting stages. As blood glucose levels rise, the pancreas releases insulin to stimulate the uptake of glucose by hepatocytes in the liver, muscle cells/fibers, and adipocytes (fat cells), and to promote its conversion to glycogen. As the postabsorptive state begins, glucose levels drop, and there is a corresponding drop in insulin levels. Falling glucose levels trigger the pancreas to release glucagon to turn off glycogen synthesis in the liver and stimulate its breakdown into glucose. The glucose is released into the bloodstream to serve as a fuel source for cells throughout the body. If glycogen stores are depleted during fasting, alternative sources, including fatty acids and proteins, can be metabolized and used as fuel. When the body once again enters the absorptive state after fasting, fats and proteins are digested and used to replenish fat. |
SciQ | SciQ-7513 | human-biology, physiology, metabolism
Thus, carbon dioxide (in the form of bicarbonate) is an obligate requiement for mammalian fatty acid biosynthesis, but no CO2-derived carbon is incorporated into fatty acids.
Carbon dioxide is also required for oxaloacetate formation from pyruvate. This reaction may be though of a method of 'filling up' a key Krebs Cycle intermediate (a so-called anapleurotic reaction). The enzyme here is pyruvate carboxylase and the substrates for the reaction are pyruvate, bicarbonate and ATP, with oxaloacetate being a key product. This enzyme also contains biotin and (like acetyl CoA carboxylase), CO2 becomes covalently bound to biotin during the reaction cycle.
Pyruvate-CoA carboxylase was discovered by Harland.G Wood and C. Werkman in bacteria (See here for a good reference on the early work on pyruvate carboxylase). Its discovery was very controversial because at the time it was thought that animal/bacterial cells could not 'fix' CO2; that is it was though that CO2 is only 'fixed' in photosynthesis. This discovery disproved that piece of dogmatism.
A third enzyme that requires CO2 as substrate (in the form of bicarbonate) is propionyl-CoA carboxylase. This enzyme occurs in mitochondria and functions in odd-chain fatty acid metabolism. It also contains biotin.
I have concentrated on some biochemical aspects of your question. The three enzymes mentioned, acety-CoA carboxylase, pyruvate carboxylase and propionyl-CoA carboxylase all require CO2 in the form of bicarbonate as substrate, all contain biotin, and (as far as I am aware) all play very central roles in mammalian metabolism. (They also all require ATP as substrate).
The following is multiple choice question (with options) to answer.
Hydrocarbons are combined with oxygen in a series of enzymatic steps to product water, carbon dioxide, and energy, which is stored in the form of what? | [
"reactive molecules",
"dormant molecules",
"energy",
"light"
] | A | The process of cellular respiration can be thought of as a highly controlled version of a combustion reaction. We do not literally burn hydrocarbons in our body, but the overall reactants and products are the same. Hydrocarbons, such as sucrose (C 12 H 22 O 11 ), are combined with oxygen in a series of enzymatic steps to product water, carbon dioxide, and energy, which is stored in the form of reactive molecules. The unbalanced chemical equation for this overall process is shown below:. |
SciQ | SciQ-7514 | quantum-mechanics, bells-inequality
A variant of this would be a deterministic universe where the initial conditions are chosen very carefully to ensure the above sort of correlation between the hidden fruits sent out on each trial and which boxes the experimenters choose to scratch on each trial. The assumption that there is no "conspiracy" in the initial conditions of the universe which predetermines a strong correlation between the hidden variables associated with particles on each trial (or hidden fruits on each pair of cards in my analogy) and what variables the experimenters will choose to measure on each trial (or what boxes they will choose to scratch) is often called the "no conspiracy" assumption, see the paper on the detailed assumptions of Bell's theorem here which discusses it in section D on page 6. Models with violations of no-conspiracy that depend on fine-tuning of initial conditions are sometimes grouped under the label "superdeterminism", see here and here for example.
Another subtle variation on this is the idea that the entity doesn't actually cause the experimenters to make particular choices but merely has a sort of "precognition" about what choices they will in fact make (implying some backwards-in-time causality), and determines what fruits will be under the two boxes that it knows will be scratched in the future using the same type of rule as above. The philosopher of science Huw Price discusses such an idea in his book Time's Arrow and Archimedes' Point.
(As I mentioned in a comment above, advocates of the many-world interpretation also make the point that one can preserve locality if one drops the assumption that each measurement gives a single unique result, as elaborated in this paper by David Deutsch. If you want a simple conceptual toy model of how this could work, see this post I wrote up on physicsforums.com a while ago).
The following is multiple choice question (with options) to answer.
The validity of thought experiments, of course, is determined by this? | [
"actual observation",
"hypothetical observation",
"theoretical observation",
"predictive observation"
] | A | Now consider what observer B sees happen to observer A. Observer B perceives light from the right reaching observer A before light from the left, because she has moved towards that flash lamp, lessening the distance the light must travel and reducing the time it takes to get to her. Light travels at speed c relative to both observers, but observer B remains equidistant between the points where the flashes were emitted, while A gets closer to the emission point on the right. From observer B’s point of view, then, there is a time interval between the arrival of the flashes to observer A. From observer B’s point of view, then, there is a time interval between the arrival of the flashes to observer A. In observer A's frame of reference, the flashes occur at different times. Observer B measures the flashes to arrive simultaneously relative to him but not relative to A. Now consider what observer A sees happening. She sees the light from the right arriving before light from the left. Since both lamps are the same distance from her in her reference frame, from her perspective, the right flash occurred before the left flash. Here a relative velocity between observers affects whether two events are observed to be simultaneous. Simultaneity is not absolute This illustrates the power of clear thinking. We might have guessed incorrectly that if light is emitted simultaneously, then two observers halfway between the sources would see the flashes simultaneously. But careful analysis shows this not to be the case. Einstein was brilliant at this type of thought experiment (in German, “Gedankenexperiment”). He very carefully considered how an observation is made and disregarded what might seem obvious. The validity of thought experiments, of course, is determined by actual observation. The genius of Einstein is evidenced by the fact that experiments have repeatedly confirmed his theory of relativity. In summary: Two events are defined to be simultaneous if an observer measures them as occurring at the same time (such as by receiving light from the events). Two events are not necessarily simultaneous to all observers. |
SciQ | SciQ-7515 | genetics, evolution, population-genetics, population-biology, allele
Title: Relationship between genetic diversity within and between species Here is a quote from Wagner (2008)
A second line of evidence [against neutralism] comes from the relationship between the mean number of polymorphic differences between alleles within a species, $\pi$, and the number of fixed differences between genes in two species, $d$. For neutral mutations, a positive association between $\pi$ and $d$ should exist, because the neutral theory predicts that both quantities are linearly proportional to the rate at which neutral mutations arise. Recent genome-scale data shows instead that this association is in fact negative.
What do "the mean number of polymorphic differences between alleles within a species" and "the number of fixed differences between genes in two species" have to do with each other? Why should there be any relationship at all? And by "two species", are they talking about Eastern Yellowback Whooping Finches versus Western Yellowback Whooping Finches, or any arbitrary two species, like E. Coli versus Muskrats?
I found this related question, but it doesn't say anything about different species. Metrics of interest
The two metrics you are interested in are
$\pi$ - the mean number of differences between two randomly sampled (with replacement) alleles in a population
$d$ - the mean number of differences between two randomly sampled (with replacement) alleles coming from two different species
Consider two sequences
ATCGTCAAT
ATAGTTAAT
There are 2 pairwise differences between these two sequences (positions 3 and 6).
The whole point here is to understand that two individuals in the same population coalesce at a given time in the past just like two individuals coming from two different species. The number of pairwise differences is just equal to the rate at which mutations accumulate multiplied by the coalescence time. Let me develop this idea with a few equations below.
Neutral Expectations
Let's do the math! We will do two important assumptions below.
Every mutation makes a new allele (it is an infinite allele model)
All mutations are substitutions (no indels, no gene duplication, etc...)
The following is multiple choice question (with options) to answer.
What do you call a close relationship between two species that benefits both? | [
"parasitic relationship",
"commensalism",
"symbiotic relationship",
"primordial relationship"
] | C | Many fungi get organic compounds from living organisms. They have close relationships with other species. A close relationship between two species is called a symbiotic relationship. Two symbiotic relationships in fungi are mycorrhiza and lichen. These relationships are beneficial for both species. |
SciQ | SciQ-7516 | thermodynamics, energy, electricity, efficient-energy-use
Title: Cutting down on power by bypassing mechanical to electrical conversions: Why not? The only answer to this I can think of is energy portability issues.
Another modern-world insanity is converting mechanical energy to electrical, only to turn it back into mechanical. The example I like to use is a refrigerator's reciprocating compressor.
If we directly attach a steam turbine's axle to the crankshaft of the compressor, we will not need to suffer losses in heat in our conversion of mechanical to electrical (at the power plant) then back to mechanical energy (in our appliance). Long ago, a primitive factory used one big engine or turbine or water wheel to rotate a set of overhead shafts, from which leather belts were suspended at intervals to power small pieces of machinery scattered throughout the factory. This arrangement was inflexible in that when the single big engine stopped, so did the entire factory, and when electricity came into common use, this overhead shafting arrangement fell quickly out of favor.
The power losses in long-distance electrical power transmission are more than made up for by the ease with which it is performed and the flexibility it affords. This makes "local power generation" as you describe it impractical because a hundred small steam turbines are much more wasteful of heat energy than one large turbine.
The only practical exception is integrated co-generation in which a small engine running on, for example, natural gas powers a generator while also spinning the shaft of a heat pump. The waste heat from the engine's cooling system makes residential hot water, the waste heat from its exhaust goes through a heat exchanger to provide hot air for space heating, the heat pump furnishes air conditioning (or pulls heat from outside the dwelling) and the electricity from the generator powers up your small appliances in the home while also charging a set of batteries.
Overall thermodynamic efficiency of such a device can exceed 95%, and examples of this technology are just now coming onto the market.
The following is multiple choice question (with options) to answer.
Generators convert mechanical energy to which kind? | [
"kinetic",
"radiation",
"electrical",
"static"
] | C | Generators and motors are almost identical in construction but convert energy in opposite directions. Generators convert mechanical energy to electrical energy and motors convert electrical energy to mechanical. |
SciQ | SciQ-7517 | synthetic-biology, prokaryotes
It should be noted that it is possible for eukaryotes to generate mRNA encoding multiple proteins, but as it was assumed for a long time that this was unique to prokaryotes, there is less research for this in eukaryotes. This paper has some useful information: https://academic.oup.com/femsyr/article/2/2/215/536601.
Because of these differences, for most applications, if co-expression in bacteria is required it is much simpler to add in multiple RBSs and stop codons than to rely on something like 2A peptides which, as you mentioned, do not always work and can result in fused proteins. However in eukaryotes, techniques such as 2A peptides are important considerations for co-expression as poly-cistronic mRNA (mRNA encoding multiple proteins) seem to be much less common.
This doesn't mean that there aren't applications for 2A peptides in bacteria, but they are much more specific and hence their use doesn't turn up so much in the literature.
These wikipedia pages have some good reading and references:
The following is multiple choice question (with options) to answer.
What is common in two eukaryotic proteins? | [
"one domain",
"cells",
"DNA",
"translation"
] | A | |
SciQ | SciQ-7518 | galaxy
Title: Brown bands in Andromeda galaxy? Many images of the Andromeda galaxy depict a yellow-red-ish bright center and then those brown "dust layers" around the center. As far as I know the bright light comes from stars, but what is this "brown dust"? It is the remains of dead stars.
Large stars are able to fuse light elements (like helium) to make heavier ones (like Carbon, Oxygen and Silicon, but also all the elements found on Earth). When these stars die, some of these heavier elements are ejected into space, where they condense to form dust particles. The dust particles are small, typically a few micrometres long (similar in size to a bacteria). The dust particles are mixed with gas and ices and form nebulae. If the gas and dust can become compressed enough, then clumps of dust and gas can collapse to form new stars, and planets. Every carbon atom in your body started out in interstellar dust.
The dust is therefore composed of normal matter, and in fairly familiar forms, such as "silicon oxide" (which is what much of the rock on Earth is made of) There are also carbon grains, and metals: aluminium, magnesium and iron (usually as oxides).
The following is multiple choice question (with options) to answer.
What do you call egg-shaped galaxies, which are reddish to yellowish in color because they contain mostly old stars? | [
"conical galaxies",
"spiral galaxies",
"elliptical galaxies",
"irregular galaxies"
] | C | Pictured below is a typical elliptical galaxy ( Figure below ). As you might have guessed, elliptical galaxies are elliptical, or egg-shaped. The smallest elliptical galaxies are as small as some globular clusters. Giant elliptical galaxies can contain over a trillion stars. Elliptical galaxies are reddish to yellowish in color because they contain mostly old stars. |
SciQ | SciQ-7519 | newtonian-mechanics, mass, momentum, conservation-laws
Title: Losing mass in space So I came across a question while studying laws of motion. Roughly, this is how it goes:
There are two astronauts in a space shuttle, who together have mass 200 kg. If by doing exercise, they manage to lose 80 kg, what will be the percentage increase in speed of the shuttle. The question is pretty straight forward, if thought about directly. However, my instant reaction was that by conservation of mass, the mass that the astronauts lose will still be contained within the space ship in the form of water, CO2, etc. So technically there won't be any change in mass, thus no change in speed.
I would like to know if this assumption is correct and in what forms is the mass we lose released. I'll attempt an answer, though someone knowing the precise ground realities will most likely improve on my answer.
You make a very good point about the speed staying constant IF the space ship can be treated as a closed system. That's the sole point that we need to worry about.
Naturally, the atmosphere within a space ship has to be maintained (at the values that can support human beings). If it was just a case of filling up the shuttle once with $21 \%$ oxygen and being done with it, astronauts would keep consuming it so that its levels would fall, and percentage of ${\rm CO}_2$ would keep increasing. That's undesirable and in a simplified description, one can get around this by removing ${\rm CO}_2$ via a chemical reaction with Lithium Hydroxide ${\rm LiOH}$. (By the way, this is a fairly common use of ${\rm LiOH}$, as a Carbon Dioxide Scrubber in breathing purification systems, as can be seen here.) Upon the reaction, these ''canisters'' can be stored and disposed off later. All the excess water (i.e. discounting the potable variety) is directed to tanks, which can again be disposed later. Excess heat is handled by converting to ammonia vapor and subsequent STORAGE. (Though somewhat simplified, a description of this process can be found in the first link of this article.)
The following is multiple choice question (with options) to answer.
When it was found that, without the force of gravity exerting pressure on the bones, bone mass was lost in astronauts, what kind of exercise provided an antidote? | [
"sedentary",
"anaerobic",
"resistive",
"aerobic"
] | C | Additionally, the yellow marrow, which is found in the central cavity of long bones along with red marrow, serves as a storage site for fat. 42 Structurally, the femur is a long bone, meaning its length is greater than its width, while the patella, a sesamoid bone, is small and round. Functionally, the femur acts as a lever, while the patella protects the patellar tendon from compressive forces. 44 The densely packed concentric rings of matrix in compact bone are ideal for resisting compressive forces, which is the function of compact bone. The open spaces of the trabeculated network of spongy bone allow spongy bone to support shifts in weight distribution, which is the function of spongy bone. 46 A single primary ossification center is present, during endochondral ossification, deep in the periosteal collar. Like the primary ossification center, secondary ossification centers are present during endochondral ossification, but they form later, and there are two of them, one in each epiphysis. 48 The internal callus is produced by cells in the endosteum and is composed of a fibrocartilaginous matrix. The external callus is produced by cells in the periosteum and consists of hyaline cartilage and bone. 50 Astronauts floating in space were not exerting significant pressure on their bones; they were “weightless. ” Without the force of gravity exerting pressure on the bones, bone mass was lost. To alleviate this condition, astronauts now do resistive exercise designed to apply forces to the bones and thus help keep them healthy. 52 Under “normal” conditions, receptors in the parathyroid glands bind blood calcium. When the receptors are full, the parathyroid gland stops secreting PTH. In the condition described, the parathyroid glands are not responding to the signal that there is sufficient calcium in the blood and they keep releasing PTH, which causes the bone to release more calcium into the blood. Ultimately, the bones become fragile and hypercalcemia can result. |
SciQ | SciQ-7520 | meteorology, weather-forecasting, rainfall, rain
Title: Is there a consensus on the "heaviness" of rain? As part of the home dashboard I am developing, I get information about incoming rain. It is given in mm/min.
Is there a consensus on the precipitation rate that is called "light rain", or "heavy rain"? (I would like, if this is possible, to use some standardized naming) The German Weather Service (Deutscher Wetterdienst, DWD) provides the following definitions:
Heavy rain is defined as large amounts of precipitation during a fixed period of time. [...]
The DWD issues warnings of heavy rain using three categories:
heavy rain: 15 to 25 l/m² within 1 hour or 20 to 35 l/m² within 6 hours
severly heavy rain: 25 to 40 l/m² within 1 hour or 35 to 60 l/m² within 6 hour
extremely heavy rain: above 40 l/m² within 1 hour or above 60 l/m² within 6 hour
Source: https://www.dwd.de/DE/service/lexikon/begriffe/S/Starkregen.html and https://www.dwd.de/DE/wetter/warnungen_aktuell/kriterien/warnkriterien.html?nn=508722#doc453962bodyText3, translation my own.
Heavy rain is distinct from constant rain by the period of time, over which the rain falls, as well as the total amount of rain per m². Still, heavy rain events may be part of constant rain periods.
The following is multiple choice question (with options) to answer.
What can occur during periods of heavy rain? | [
"glaciers",
"earthquakes",
"volcanoes",
"floods"
] | D | |
SciQ | SciQ-7521 | forces, potential-energy, conventions, vector-fields, conservative-field
Of course, this is all a convention -- if you'd like, you can define a "potential schmenergy" function $\tilde{V} = -V$, and then $\vec{F} = + \nabla \tilde{V}$. None of the physics would be changed, except that objects would fall from low to high potential schmenergy, which might go against the grain of your intuition.
The following is multiple choice question (with options) to answer.
What type of energy can be used to change the position or shape of an object, thus giving it potential energy? | [
"kinetic energy",
"harmonic energy",
"static energy",
"binary energy"
] | A | Mechanical energy commonly changes between kinetic and potential energy. Kinetic energy is the energy of moving objects. Potential energy is energy that is stored in objects, typically because of their position or shape. Kinetic energy can be used to change the position or shape of an object, giving it potential energy. Potential energy gives the object the potential to move. If it does, the potential energy changes back to kinetic energy. |
SciQ | SciQ-7522 | electric-circuits, electric-current, electrical-resistance
and so
$$ { V_{\rm{out}} } = V_{\rm{in}} \times { R_{\rm{bottom}} \over R_{\rm{top}} + R_{\rm{bottom}} }$$
This is the equation for the potential divider. Note that the fraction on the right hand side ${ R_{\rm{bottom}} / (R_{\rm{top}} + R_{\rm{bottom}} })$ is a number between $0$ and $1$ so the output voltage is smaller than the input voltage or we could say the 'voltage is divided' or the 'potential is divided' by the 'potential divider'.
The following is multiple choice question (with options) to answer.
What equals the output power divided by the input power? | [
"potential",
"inertia",
"efficiency",
"output"
] | C | ; The efficiency equals the output power divided by the input power. |
SciQ | SciQ-7523 | mathematical-models, population-dynamics
Title: Range of feasible coefficients in an unlimited growth model If you are given an unlimited growth model in the form:
$\frac {dP(t)}{dt} = k P(t)$
Obviously the population growth would never be unlimited, but let's presume for the moment that we are introducing a species into an environment where there is the possibility for unlimited growth, at least on for a given time -- i.e. invasive species.
$k$ is some rate of growth of the population at time $t$, denoted by $P(t)$
What are some feasible values of $k$? In other words, if a number is way above or way below $k$, where would I know that the research I am reading is preposterously off-base?
I am sure it is different for different types of animals, including mammals, birds, bacteria, etc. A solid limit: k must be greater than zero. Unless you're talking about some cannibalistic species or something that isn't suited to the model at all.
As long as the species is productive in the new environment: k is greater than 1. The population is probably growing or again you probably won't be using an exponential growth model.
As mentioned before you would need to know the species for more information. But if you look at generation times and litter sizes:
Some bacterial generation times (from here) range from 10 to
2000 minutes (33 hours). So that is $k=2$ per generation time. Per
day you're looking at a lower bound of 2 per day and an upper bound
of $k=2^{14}=10^{43}$ per day.
Mice are something like 12 week generation time and a litter of 10
giving something like $k=10^{10}$ per year.
Elephants are one young every 25 years. So $k=16$ per century or so.
Of course this is all based on gross assumptions. But you're looking for guidelines for a unrealistic model so hopefully they'll do.
The following is multiple choice question (with options) to answer.
Overpopulation takes place when the number of organisms in an area exceeds what? | [
"biome size",
"predators",
"carrying capacity",
"consumers"
] | C | Overpopulation takes place when the number of organisms exceeds the carrying capacity of the region. What is the carrying capacity of Earth for humans? Are seven billion people the human carrying capacity? Nine billion? We don't know yet. |
SciQ | SciQ-7524 | particle-physics, astrophysics, education
Title: Are leptons, baryons and energy the only products of radioactive decay? I recently visited my child's elementary school to speak to a science classroom about rocks and minerals. While trying to explain what a crystal is, I got sloppy and mis-spoke that an atom was the smallest possible piece of matter (rather than an element!) I was quickly stopped and corrected by a 9-year-old that told me in fact atoms can be split into leptons and baryons. I told her she was right, and explained that if an atom of an element is divided it becomes a different element (overlooking isotopes!).
My knowledge of particle physics is limited and later I began wonder what I might be leaving out, that should not be left out, when talking of the types of 'ordinary matter' in nature. What happens in high-energy physics experiments aside. I know that there are other elementary particles besides leptons and baryons, photons are obviously everywhere.
But if we restrict the discussion to radioactive decay, fusion in stars, cosmic rays, is everything a lepton, baryon, or a photon? Your
What happens in high-energy physics experiments aside
partially contradicts your final question
But if we restrict the discussion to radioactive decay, fusion in stars, cosmic rays, is everything a lepton, baryon, or a photon?
Radioctive decay has as end products photons, leptons and baryons.
Fusion and cosmic rays are the realm of elementary particle physics, the energies involved much higher than the ones in natural radiaoctivity.
The reality of what "everything is made up of" depends on the energy with which you look at "everything". The answer is that everything is made up by the elementary particles, following the rules of the standard model, nuclear models, atomic models as the energies involved in "looking" at everything diminish. It is a compositeness built up consecutively. You might be interested in this answer to a similar question.
These are the elementary particles out of which all matter is formed. Every day matter involve mainly the first column and the last column . The two middle ones have been found in cosmic rays to start with and in accelerator experiments that led to the discovery of the standard model. They are particles that cannot come out from nuclear decays or fissions, i.e. "naturally" but need excess energy to materialize.
The following is multiple choice question (with options) to answer.
There are six fundamentally different kinds of nuclear decay reactions, and each releases a different kind of particle or what? | [
"energy",
"protein",
"mineral",
"mass"
] | A | an identical particle that has been ejected from a heavier nucleus. There are six fundamentally different kinds of nuclear decay reactions, and each releases a different kind of particle or energy. The essential features of each reaction are shown in Figure 20.4 "Common Modes of Nuclear Decay". The most common are alphaand beta decay and gamma emission, but the others are essential to an understanding of nuclear decay reactions. Figure 20.4 Common Modes of Nuclear Decay. |
SciQ | SciQ-7525 | physical-chemistry, metals
Title: Why is quicksilver (mercury) liquid at room temperature? This is a nice question when you find it out, and I am really looking for a proper answer.
Take quicksilver (Hg) in the periodic table. It has one proton more than Gold (melting point 1337.33 K), and one less than Thallium (melting point 577 K). It belongs to the same group as Zinc (692.68 K) and Cadmium (594.22 K). All not very high melting points, but still dramatically higher than quicksilver (234.32 K). When his neighbors melt, quicksilver vaporizes (at 629.88 K).
What is the reason for this exceptional behavior of quicksilver ? Although the question has been partially answered, there is a superb reference on this topic which will certainly give you some of the deep, and not so deep insights needed to understand the answer to this question.
http://pubs.acs.org/doi/abs/10.1021/ed068p110
Nevertheless, both the contraction of the s(1/2) orbitals predicted by the Dirac equation, and the filled valence shell of Hg are the major causes for the odd physical properties of Hg. However, there are other effects that should be considered and the paper above is pretty clear on those.
Let me reformulate in order to make things clearer and more specific:
The reason for liquid Hg can be stated simply: the outer electrons of Hg (6s2) that participate in metallic bonds are "less available" to bonding (which might be observed for example by looking at binding energies of clusters of Hg, dimers, etc) then in other common metals, and hence the interaction between Hg atoms is much weaker compared to other metal-metal bonds. The explanation for the "less availability" of the 6s electrons is the contraction of the 6s orbitals, caused by the high speeds achieved by those electrons. This effect is promptly predicted by the Dirac equation.
The following is multiple choice question (with options) to answer.
What is the only metal that is a liquid at room temperature? | [
"copper",
"tin",
"aluminum",
"mercury"
] | D | The elements mercury, gold, and copper display properties that are common of metals. Mercury ( left ) is the only metal that is a liquid at room temperature. Even in its liquid form, it still has a high luster. Gold ( middle ) is malleable and can be formed into very thin sheets called gold leaf. Because copper ( right ) is ductile, inexpensive, and a good conductor, it is used extensively in electrical wiring. |
SciQ | SciQ-7526 | human-biology, cardiology
Title: How can a heart of human work if one of its valve is not working? Yesterday I went to a hospital and heard a doctor say that one of the heart valves of a patient is not working. However, the patient was still alive and was healthy; the patient could walk and talk too. I could not understand it because I have read that all valves of heart are extremely important. I have tried searching on google but all I could find was heart attack problems. It is not possible that one of the valve is completely closed and the person is still alive without being in ICU. I think what the doctor was trying to communicate to the patient was that one of the valves is in the process of complete closure. There are three main types of diseases associated with heart valves :-
1- Blood flows backwards
2- Heart valve opening becomes narrow
3- upper condition may lead to complete closure
For details see the following link:-
http://www.nhlbi.nih.gov/health/health-topics/topics/hvd
http://en.wikipedia.org/wiki/Pulmonary_atresia
Hope you understand. :)
The following is multiple choice question (with options) to answer.
Heart valves prevent what kind of blood flow from happening in the heart? | [
"quick flow",
"backflow",
"irregular flow",
"slow flow"
] | B | |
SciQ | SciQ-7527 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
What is the source of energy for photosynthesis? | [
"air",
"gravity",
"carbon",
"light"
] | D | The energy for photosynthesis comes from light. Without light energy, photosynthesis cannot occur. As you can see in the Figure below , plants can get the energy they need for photosynthesis from either sunlight or artificial light. |
SciQ | SciQ-7528 | waves, electromagnetic-radiation, acoustics, interference, noise
Title: Destructive Interference applied to ElectroMagnetic Waves? For active noise cancelling (in for example headphones) a process called 'destructive interference' is used.
The following is multiple choice question (with options) to answer.
Different types of interference include destructive and what else? | [
"helpful",
"constructive",
"active",
"consistent"
] | B | 2t = λ n / 2, 3λ n / 2, 5λ n / 2, … . To know whether interference is constructive or destructive, you must also determine if there is a phase change upon reflection. Thin film interference thus depends on film thickness, the wavelength of light, and the refractive indices. For white light incident on a film that varies in thickness, you will observe rainbow colors of constructive interference for various wavelengths as the thickness varies. Example 27.7 Soap Bubbles: More Than One Thickness can be Constructive (a) What are the three smallest thicknesses of a soap bubble that produce constructive interference for red light with a wavelength of 650 nm? The index of refraction of soap is taken to be the same as that of water. (b) What three smallest thicknesses will give destructive interference? Strategy and Concept Use Figure 27.33 to visualize the bubble. Note that water). There is a. |
SciQ | SciQ-7529 | human-biology, cancer, medicine
Title: Why are only few cigarette smokers prone to cancer? It's tacit that only a few populace of smokers get cancer. What spares the others from it or what specifically cause cancer in those populace? See this Washington Post Article Cigarette smokers are most certainly prone to cancer. See Cecil Medicine, Chapter 183, on the epidemiology of cancer, exposure to tobacco is the most important environmental risk factor for cancer development, at least in the US:
Exposure to tobacco is the single largest cause of cancer in the United States... All forms of tobacco can cause cancer. Cigarette smoking causes cancer of the lip, oral cavity, nasal cavity, paranasal sinuses, pharynx (nasal, oral, and hypopharnyx), larynx, lung, esophagus (squamous cell and adenocarcinoma), stomach, colorectum, pancreas, liver, kidney (adenocarcinoma and renal pelvis), urinary bladder, uterine cervix, and myeloid leukemia.
Cancer may be identified or the cause of death in fewer smokers than might be expected, though, because smoking is an even greater risk factor for cardiovascular disease, and death due to cardiovascular disease.
Cancer is an unlikely phenomenon in an individual cell, but becomes more likely at the organism level, and even more likely over time. Though tobacco may be the most important environmental risk factor for cancer, age is actually a stronger predictor of cancer (see again, Cecil Chapter 183. Autopsy studies give us a quite remarkable example, this one shows incidental prostate cancer in nearly 60% of men over 80 who died from other causes. That figure is not out of the ordinary. Live long enough and you are likely to develop cancer.
Death due to heart disease may account for the lower than expected rates of cancer diagnoses and deaths in smokers. Nothing prevents cancer as well as dying from something else. And as discussed in the blog in the Washington Post you linked to, up to 2/3 of smokers die from smoking related causes
The following is multiple choice question (with options) to answer.
What is anything that causes cancer called? | [
"chemical",
"bacteria",
"carcinogen",
"pesticide"
] | C | A carcinogen is anything that causes cancer. Most carcinogens produce mutations in genes that control the cell cycle. |
SciQ | SciQ-7530 | physical-chemistry, solutions, vapor-pressure
Title: Can we compare the vapour pressure of solutions whose concentrations and temperature is known?
If we have some solutions, in which we know the temperature and concentration of the solute particles, can we compare their vapour pressures?
Original question:
Which solution has the highest vapour pressure among the following?
a) $0.02 ~\pu M ~\ce{NaCl}$ at $50^{\circ}$C b) $0.03 ~\pu{M}$ sucrose at $15^{\circ}$C c) $0.005 ~\pu{M} ~\ce{CaCl_2}$ at $50^{\circ}$C d)$0.005~ \pu{M} ~ \ce{CaCl_2}$ at $25^{\circ}$C
The following is multiple choice question (with options) to answer.
In comparing two solutions of unequal solute concentration, the solution with the higher solute concentration is called what? | [
"hypothermic",
"acetic",
"hydrophilic",
"hypertonic"
] | D | Imagine now that you have a second cup with 100ml of water, and you add 45 grams of table sugar to the water. Just like the first cup, the sugar is the solute, and the water is the solvent. But now you have two mixtures of different solute concentrations. In comparing two solutions of unequal solute concentration, the solution with the higher solute concentration is hypertonic , and the solution with the lower solute concentration is hypotonic . Solutions of equal solute concentration are isotonic . The first sugar solution is hypotonic to the second solution. The second sugar solution is hypertonic to the first. |
SciQ | SciQ-7531 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What broad group of animals - which includes rats, dogs and camels - have highly developed brains and often perform work for humans? | [
"amphibians",
"reptiles",
"arachnids",
"mammals"
] | D | We see examples of mammals (other than people!) serving our needs everywhere. We have pets that are mammals, such as dogs and cats. Mammals are also used around the world for transport. For example, horses, donkeys, mules, or camels ( Figure below ) may be the primary means of transport in some parts of the world. Mammals also do work for us. Service dogs can be trained to help the disabled. These include guide dogs, which are assistance dogs trained to lead blind and visually impaired people around obstacles. Horses and elephants can carry heavy loads. Humans also use some mammals for food. For example, cows and goats are commonly raised for their milk and meat. Mammals’ more highly developed brains have made them ideal for use by scientists in studying such things as learning, as seen in maze studies of mice and rats. |
SciQ | SciQ-7532 | biochemistry, cell-biology, metabolism, photosynthesis
Title: How are ions 'pumped' across a membrane during electron transport? A number of sites (including this one) that provide descriptions of photosynthesis state that high energy electrons 'pump' ions across a membrane. What is the actual 'pumping' mechanism? I've looked at Wikipedia and at a number of YouTube lectures/tutorials but so far have only found statements as to the where and when but not the how of this important process. Short answer:
Electrons flow through membranes by floating through kind of channels made out of iron-sulfur clusters.
Long answer:
Let's take a look at the electron transport chain in the inner mitochodrial membrane. There is a proton gradient across the membrane building up a potential difference by pumping protons across the membrane as electeons flow through the respiratory chain. They (electrons) like to flow throught the respiratory chain because they can go from enzyme to enzyme each with a lower standart free energy. These enymes together form one big complex within the inner membrane with Fe-S clusters enabeling electrons to flow through the membrane by giving them a kind of a power stroke (see here).
This as an simplyfied answer on a example.
The following is multiple choice question (with options) to answer.
What term describes a way that small molecules or ions move across the cell membrane without input of energy by the cell? | [
"physical transport",
"immune transport",
"impassive transport",
"passive transport"
] | D | Passive transport is a way that small molecules or ions move across the cell membrane without input of energy by the cell. The three main kinds of passive transport are diffusion (or simple diffusion), osmosis, and facilitated diffusion. Simple diffusion and osmosis do not involve transport proteins. Facilitated diffusion requires the assistance of proteins. |
SciQ | SciQ-7533 | human-biology, physiology, proteins, amino-acids, diet
Title: Amino Acid requirement + intake in relation to diet + meat type I was arguing with a friend:
I said: The Yulin festivals cannot be condemned by western culture, as we also kill animals in equally cruel ways.
She said: It isn't just that the killing is cruel, but it doesn't help us, as humans do not derive the same essential amino acids from consuming these less traditional meats (e.g. dogs, cats, etc) like they would from consuming more traditional meats (e.g. cow, pig, goat, etc) She cites her father, a geneticist, as her source.
Question one:
Are my friend and her father correct? Does the consumption of a less traditional meat (e.g. cats, dogs, etc) provide fewer essential amino acids than the consumption of traditional meats (e.g. cows, pigs, chickens, etc)?
Question two:
My friend also made a comment about veganism and vegetarianism (I am a vegetarian), stating that for the same reason as her and her father's above comment, people who exclude meat from their diet need to use supplements. Is this correct, or would it also be possible to just vary diet to obtain these essential amino acids? There is a difference between animals in their requirements for amino acids. For example, cats need high amounts of taurine (and can't make it) and when fed diets lacking enough can go blind. This is why vegans trying to feed vegan diets to their pets can be very bad for the pet. Animal proteins have sufficient taurine for the cat.
However, the meat of a cat or dog is just as a complete source of protein for humans as any other meat. All essential amino acids are there in sufficient ratios. Suggesting otherwise by her father suggests some confusion between the dietary needs of cat vs. the nutritional value of the cat to another predator.
Your second question is easily answered by looking up essential amino acids. Wiki is plenty sufficient to get the gist Wiki Link. In short, most plants don't contain the full complement of amino acids that humans require (and can't make on their own). So to get this full complement, it requires eating multiple plant products that together contain the required amino acids.
From Harvard School of Public Health
The following is multiple choice question (with options) to answer.
Do most humans feed at one trophic level, or more than one? | [
"more than one",
"none",
"one",
"less than one"
] | A | Many consumers feed at more than one trophic level. Humans, for example, are primary consumers when they eat plants such as vegetables. They are secondary consumers when they eat cows. They are tertiary consumers when they eat salmon. |
SciQ | SciQ-7534 | waves
Title: Is wave motion the combined motion of the disturbance and the medium? Using a textbook slinky as an example, if the disturbance propagates through the slinky from left to right and the particles of the slinky vibrate up and down, does that mean 'wave motion' is also associated with the medium? Since the motion of the wave that we perceive is the combined motion of the disturbance and the medium? This answer is maybe not the most straightforward satisfactory answer to your stated question, but I think it anticipates ways of thinking that are used in more advanced areas of physics.
There are two pictures of what a wave is.
A wave is coherent motion in a medium; as time progresses energy moves through the medium and vibrations occur in different locations.
A wave is a propagating disturbance. It is not made of anything, the word "wave" refers a disturbance which propagates energy from one place to another.
Your question kind of implies that a wave is some combination of 1 and 2. I would say that either 1 or 2 are valid pictures, but you should treat them as distinct pictures of the same physical phenomenon and not reason about both simultaneously.
The advantage of the first picture is that it gives you a clear mechanical model of what is going on at a fundamental level; if you zoom in there are particles in the material, and the particles are oscillating back and forth in tandem -- that coherent motion is a wave. However, the disadvantage is that wave phenomena occur in many circumstances, and there are features of any particular example that will not generalize and can lead you astray if you take them too seriously. For example, light traveling in vacuum cannot be accurately visualized as motion of particles.
The advantage of the second picture is that it is more abstract and general -- wave phenomena occur in all kinds of materials, and so there is no need to specify which specific material you are thinking of, because we can make very general statements about waves that apply to any material. The disadvantage is that it can be hard to wrap your head around a disturbance without a medium, and also sometimes trying to be too general means you miss special aspects of the particular situation you might be interested in (for example, cool behavior like solitons can occur in water but not in light propagating in vacuum).
The following is multiple choice question (with options) to answer.
What is it called when two waves combine to create a larger wave? | [
"consistent interference",
"Destructive Interference",
"wave propagation",
"constructive interference"
] | D | Constructive interference occurs when two waves combine to create a larger wave. This occurs when the peaks of two waves line up. |
SciQ | SciQ-7535 | homework-and-exercises, electrostatics, electricity, electric-circuits, capacitance
This also gives a nice introduction to the intimate relationship between capacitance and the presence of stray electric fields which becomes critical to understand when one starts thinking about electromagnetic interference type questions.
The following is multiple choice question (with options) to answer.
What is the study of the relationship between electricity and chemical reactions called? | [
"electrochemistry",
"inorganic chemistry",
"analytical chemistry",
"physical chemistry"
] | A | Summary Electrochemistry is the study of the relationship between electricity and chemical reactions. The oxidation–reduction reaction that occurs during an electrochemical process consists of two halfreactions, one representing the oxidation process and one the reduction process. The sum of the halfreactions gives the overall chemical reaction. The overall redox reaction is balanced when the number of electrons lost by the reductant equals the number of electrons gained by the oxidant. An electric current is produced from the flow of electrons from the reductant to the oxidant. An electrochemical cell can either generate electricity from a spontaneous redox reaction or consume electricity to drive a nonspontaneous reaction. In a galvanic (voltaic) cell, the energy from a spontaneous reaction generates electricity, whereas in an electrolytic cell, electrical energy is consumed to drive a nonspontaneous redox reaction. Both types of cells use two electrodes that provide an electrical connection between systems that are separated in space. The oxidative half-reaction occurs at the anode, and the reductive half-reaction occurs at the cathode. A salt bridge connects the separated solutions, allowing ions to migrate to either solution to ensure the system’s electrical neutrality. A voltmeter is a device that measures the flow of electric current between two half-reactions. The potential of a cell, measured in volts, is the energy needed to move a charged particle in an electric field. An electrochemical cell can be described using line notation called a cell diagram, in which vertical lines indicate phase boundaries and the location of the salt bridge. Resistance to the flow of charge at a boundary is called the junction potential. |
SciQ | SciQ-7536 | human-biology, breathing
Our lungs work off of pressure. Specifically our lungs inflate by using "negative pressure" (a word I've always hated). The pressure is not actually negative it is simply lower than the surroundings. Since there is less air in your lungs the air from the atmosphere rushes in because the pressure is higher outside your lungs. This is Boyle's Law (not the pressure outside being higher, but what happens when your lungs expand). Where an increase in Volume means a decrease in Pressure (if all else remains unchanged). In fact plants pull water up using negative pressure.
However to push out the air from our lungs we supply pressure using our muscles that overcomes the outside pressure and forces the air out.
The reason you feel your breathing change is because when that train passes by you correctly observed the strong gust of wind. This gust of wind has some force behind it that normally is not in the air you are breathing from the atmosphere. It has more force which increases the air's velocity. This actually decreases the pressure, but there's no need to get into that here (Bernoulli's).
The reason it feels like your body is "fighting to breath" is because the air is traveling in a direction with some force that you need to overcome by opening up your lungs just enough to "suck" the air in with negative pressure. This is more than the pressure you usually need to produce in order to breath in air that is "still".
What is funny to think about is we don't really have a muscle that "pulls" air in, even though it feels like you are actively doing that. The air actually rushes in on its own. All you do is expand your rib cage, which your lungs are attached to (look up on how, it's actually pretty cool), thereby making inhalation occur.
Now an interesting question for you to ask yourself is why is cold air harder to breathe?
The following is multiple choice question (with options) to answer.
What is the term for expelling air out of the body through the nose or mouth? | [
"exhalation",
"induction",
"perspiration",
"inhalation"
] | A | Most of the time, you breathe without thinking about it. Breathing is mostly an involuntary action that is controlled by a part of your brain that also controls your heart beat. If you swim, do yoga, or sing, you know you can control your breathing, however. Taking air into the body through the nose and mouth is called inhalation . Pushing air out of the body through the nose or mouth is called exhalation . The woman pictured below is exhaling before she surfaces from the pool water ( Figure below ). |
SciQ | SciQ-7537 | electromagnetism, magnetic-fields, frequency, resonance
so I'm wondering how the poster could have figured this out? There's an interesting question in here if you look hard enough.
First of all, there's nothing special about the resonant frequency of something made of little magnets. It might as well be a piece of ordinary string, a metal bar, or whatever. In fact I think the fact that it's made of separate little magnets stuck together would give it a much lower Q factor than, for example, a metal bell, which would make the resonant frequency less clear and harder to measure.
But anyway, let's assume we have some object with a mechanical resonance around 15 Hz. How do we measure this frequency with no other equipment?
As a human, there are basically two ways you can observe something's vibration frequency. If the vibration is slow enough - below about 5 or maybe 10 Hz - you can just count the individual cycles. If I'm wiggling a jump rope at the resonance frequency and count 300 wiggles per minute, then the frequency is 300/(60 s) = 5 Hz.
The other way - which works well between about 50 Hz and 10,000 Hz - is to listen to the pitch of the vibrations and figure out the frequency of that musical pitch. If I listen to a bell and hear the pitch A above middle C, that means the frequency is 440 Hz (A 440). If, like me, you don't have perfect pitch, you'll need some reference pitch to compare it too, such as a piano, but once you figure out the closest note of the musical scale, you know the frequency to within 3%.
The interesting thing in this case is that 15 Hz is right in the middle of that awkward frequency range which is too fast to count, but too low to hear.
The following is multiple choice question (with options) to answer.
The lowest resonant frequency is called the what? | [
"simplest",
"basic",
"fundamental",
"lowest"
] | C | Given that maximum air displacements are possible at the open end and none at the closed end, there are other, shorter wavelengths that can resonate in the tube, such as the one shown in Figure 17.28. Here the standing wave has three-fourths of its wavelength in the tube, or L = (3 / 4)λ′ , so that λ′ = 4L / 3 . Continuing this process reveals a whole series of shorterwavelength and higher-frequency sounds that resonate in the tube. We use specific terms for the resonances in any system. The lowest resonant frequency is called the fundamental, while all higher resonant frequencies are called overtones. All resonant frequencies are integral multiples of the fundamental, and they are collectively called harmonics. The fundamental is the first harmonic, the first overtone is the second harmonic, and so on. Figure 17.29 shows the fundamental and the first three overtones (the first four harmonics) in a tube closed at one end. |
SciQ | SciQ-7538 | tsunami, solitary-waves
Which equations govern the surface profile of a tsunami? Has this model been tested against satellite measurments? Short answer: Tsunami models use the shallow-wave mathematical approach, because their wavelength is usually much larger than the relevant water depth determining their propagation.
Long answer:
Tsunamis are often called 'tidal waves' to highlight the idea that their characteristic time response is closer to tydes than to the standard wind waves we are used to see in a beach. The full spectrum of water wave periods is shown in this figure (tsunamis being classified as long-period waves, together with waves caused by meteorological events):
Classification of the spectrum of ocean waves according to wave period. Redrawn from Figure 1 in: Walter H. Munk (1950) "Origin and generation of waves". Proceedings 1st International Conference on Coastal Engineering, Long Beach, California. ASCE, pp. 1–4.
This image shows that the wave frequency depends on the cause behind the perturbation of the water surface.
Oceanographers generally treat ocean waves as free surface waves in an ideal fluid [2].
Mathematically, tsunamis are surface gravity waves approached as shallow-water waves (see chapter 4.1.5 in here), meaning that the wavelength λ > 20H (H being the water depth). The involved shallow-water-wave mathematical approximations oppose to the deep-water waves (λ < H, see section 4.1.4 in the same [ref 3]).
Whereas for shallow waves the wave frequency and the wave speed are (ref. 3):
$ω = \sqrt {g k 2H}$ with $k = 2\pi / \lambda$
$c = \sqrt {g H}$
for deep-water waves, instead:
$ω = \sqrt {g k}$
$c = \sqrt {\frac{g \lambda}{2\pi}}$
As the wave approaches the shore and H decreases, the wave velocity decreases and energy is preserved by increasing the wave amplitude.
Detailed information here: 3.
The following is multiple choice question (with options) to answer.
Body waves and surface waves are the two major types of what, which occur during earthquakes? | [
"sound waves",
"current waves",
"seismic waves",
"tidal waves"
] | C | There are two major types of seismic waves. Body waves travel through the Earth’s interior. Surface waves travel along the ground surface. In an earthquake, body waves are responsible for sharp jolts. Surface waves are responsible for rolling motions that do most of the damage in an earthquake. |
SciQ | SciQ-7539 | human-anatomy
In the wrist, you can have palmar flexion, dorsiflexion (extension), ulnar flexion (abduction) and radial flexion (adduction) (Teachmeanatomy).
In the ankle, you can have plantar flexion, dorsiflexion (extension), inversion (inward rotation, adduction) and eversion (outward rotation, abduction). (ScienceDirect).
In the shoulder and hip, raising a limb to the same side as the limb is, is abduction (lateral extension) and raising it to the opposite side is adduction.
Moving the thumb toward the palm (in the same plane as palm) is flexion (adduction) and moving it away from it is extension (abduction).
You can read about flexion and extension and other movements here: Types of Body Movements (BCcampus)
The following is multiple choice question (with options) to answer.
Inferior rotation occurs during limb adduction and involves the downward motion of what? | [
"dialysate cavity",
"pelvic cavity",
"glenoid cavity",
"choroidal cavity"
] | C | Superior Rotation and Inferior Rotation Superior and inferior rotation are movements of the scapula and are defined by the direction of movement of the glenoid cavity. These motions involve rotation of the scapula around a point inferior to the scapular spine and are produced by combinations of muscles acting on the scapula. During superior rotation, the glenoid cavity moves upward as the medial end of the scapular spine moves downward. This is a very important motion that contributes to upper limb abduction. Without superior rotation of the scapula, the greater tubercle of the humerus would hit the acromion of the scapula, thus preventing any abduction of the arm above shoulder height. Superior rotation of the scapula is thus required for full abduction of the upper limb. Superior rotation is also used without arm abduction when carrying a heavy load with your hand or on your shoulder. You can feel this rotation when you pick up a load, such as a heavy book bag and carry it on only one shoulder. To increase its weight-bearing support for the bag, the shoulder lifts as the scapula superiorly rotates. Inferior rotation occurs during limb adduction and involves the downward motion of the glenoid cavity with upward movement of the medial end of the scapular spine. |
SciQ | SciQ-7540 | quantum-mechanics, special-relativity, speed-of-light
Title: Are photon wavelength and energy indirect measurements of one-way speed of light? First, measure the wavelength ($\lambda$) of an EM wave with, say, a chocolate bar in a microwave oven.
Then, measure its average photon energy and get the wave frequency ($\nu=\frac{E}{h}$).
Now you have the one-way speed of light ($c=\lambda\nu$)...
What is wrong here? If you assume that light satisfies a wave equation then it is true that knowing the wavelength and frequency allows you to determine the velocity.
But, assuming light satisfies a wave equation already presumes the "one-way speed of light" is constant in all directions. That is, isotropic propagation already follows from assuming you have a wave equation. So posing the question in this way is begging the question.
The interesting result of this question and line of inquiry is the realization that for the one-way speed of light to differ in different directions would require the equations governing light (the Maxwell equations) to be different than the ones we usually assume.
The following is multiple choice question (with options) to answer.
The speed of an electromagnetic wave is the product of its wavelength and what else? | [
"height",
"frequency",
"resonance",
"density"
] | B | Electromagnetic waves differ in their wavelengths and frequencies. The higher the frequency of an electromagnetic wave, the greater its energy. The speed of an electromagnetic wave is the product of its wavelength and frequency, so a wave with a shorter wavelength has a higher frequency, and vice versa. |
SciQ | SciQ-7541 | elements, periodic-table
Title: What are inner core electrons and how do they influence chemical and physical properties? There are six groups of p–block elements in the periodic
table numbering from 13 to 18. Boron, carbon, nitrogen,
oxygen, fluorine and helium head the groups. Their valence
shell electronic configuration is $\ce{ns^2 np^{1-6}}$(except for He).
The inner core of the electronic configuration may,
however, differ. The difference in inner core of elements
greatly influences their physical properties (such as atomic
and ionic radii, ionisation enthalpy, etc.) as well as chemical
properties
The above lines are from my school's textbook.
How does inner core electron create such differences and and what are inner core electrons? Inner core electrons do have a very strong affect on the chemistry of elements,for example inner d orbitals have a very poor shielding effect thus the outer electrons are bounded more strongly to the nucleus thus decreasing their reactivity and oxidation states.You will come across inert pair effect,stability of lower oxidation states down the group etc because of effect of inner core electrons.
The following is multiple choice question (with options) to answer.
Electrons in inner shells are called what? | [
"core electrons",
"valence electrons",
"surface electrons",
"inner electrons"
] | A | because of interactions between the electrons of the outermost shell of different atoms, called the valence shell electrons. Electrons in inner shells are called core electrons. Elements are grouped together by similar chemical properties into a chart called the periodic table. Vertical columns of elements are called groups or families. Some of the groups of elements have names, like the alkali metals, the alkaline earth metals, the halogens, and the noble gases. A horizontal row of elements is called a period. Periods and groups have differing numbers of elements in them. The periodic table separates elements into metals, nonmetals, andsemimetals. The periodic table is also separated into main group elements,transition metals, lanthanide elements, and actinide elements. The lanthanide and actinide elements are also referred to as inner transition metal elements. The shape of the periodic table reflects the sequential filling of shells and subshells in atoms. The periodic table helps us understand trends in some of the properties of atoms. One such property is the atomic radius of atoms. From top to bottom of the periodic table, atoms get bigger because electrons are occupying larger and bigger shells. From left to right across the periodic table, electrons are filling the same shell but are being attracted by an increasing positive charge from the nucleus, and thus the atoms get smaller. |
SciQ | SciQ-7542 | dna, chromosome
Title: Are the complementary base pairs known as genes? In my text book ,it is written that a chromosome has 1000s of genes and it is distributed throughout the chromatids except in the centromere. But we know that the chromosomes have DNAs inside them which have complementary base pairs. Then are these base pairs known as genes?? Don't assume a chromosome to be some X-shaped box that contains DNA inside it and DNA as a container of genes.
DNA, genes, Chromatid, Chromosomes are just different names at different levels of the same thing.
In molecular biology, you'll find multiple definitions of certain terms because as new insights are gained by any researcher, the definition gets modified. So one has to always make their concept clear so that they don't get confused between the same yet uniquely different terms.
So, Let's first look at how different their definitions can be:
DNA is a molecule inside cells that contains the genetic information responsible for the development and function of an organism. DNA molecules allow this information to be passed from one generation to the next. DNA is made up of a double-stranded helix held together by weak hydrogen bonds between purine-pyrimidine nucleotide base pairs: adenine (A) paired with thymine (T), and guanine (G) paired with cytosine (C). Also called deoxyribonucleic acid.
GENE, For many years the HGNC has maintained the definition of a gene as “a DNA segment that contributes to phenotype/function. In the absence of demonstrated function a gene may be characterized by sequence, transcription, or homology”. As there is still no universally agreed alternative we continue to use this definition.
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.
The following is multiple choice question (with options) to answer.
The binding of complementary bases allows dna molecules to take their well-known shape, called a what? | [
"triple helix",
"double helix",
"single helix",
"simple helix"
] | B | The binding of complementary bases allows DNA molecules to take their well-known shape, called a double helix . Figure below shows how two chains of nucleotides form a DNA double helix. A simplified double helix is illustrated in Figure below . It shows more clearly how the two chains are intertwined. The double helix shape forms naturally and is very strong. Being intertwined, the two chains are difficult to break apart. This is important given the fundamental role of DNA in all living organisms. |
SciQ | SciQ-7543 | evolution, zoology, anatomy, species
Title: Examples of animals with 12-28 legs? Many commonly known animals' limbs usually number between 0 and 10. For example, a non-exhaustive list:
snakes have 0
Members of Bipedidae have 2 legs. Birds and humans have 2 legs (but 4 limbs)
Most mammals, reptiles, amphibians have 4 legs
Echinoderms (e.g., sea stars) typically have 5 legs.
Insects typically have 6 legs
Octopi and arachnids have 8 legs
decapods (e.g., crabs) have 10 legs
....But I can't really think of many examples of animals containing more legs until you reach 30+ legs in centipedes and millipedes. Some millipedes even have as many as 750 legs! The lone example I am aware of, the sunflower sea star, typically has 16-24 (though up to 40) limbs.
So my question is: what are some examples of animals with 12-28 legs? As a couple of counterexamples, species in the classes Symphyla (Pseudocentipedes) and Pauropoda within Myriapoda have 8-11 and 12 leg pairs respectively, so between 16 to 24 legs (sometimes with one or two leg pair stronlgy reduced in size).
(species in Symphyla, from wikipedia)
Another common and species-rich group with 14 walking legs (7 leg pairs) is Isopoda.
(Isopod, picture from wikipedia)
You also need to define 'legs' for the discussion to be meaningful. As you say, decapods have 10 legs on their thoracic segments (thoracic appendages), but they can also have appendages on their abdomens (Pleopods/swimming legs), which will place many decapods in the 10-20 leg range.
(Decapod abdominal appendages/legs in yellow, from wikipedia)
So overall, in Arthropoda, having 12-28 legs doesn't seem all that uncommon. There are probably other Arthropod groups besides those mentioned here that also have leg counts in this range.
However, for a general account, the most likely answer (if there is indeed a relative lack of 12-28 legged animals) is probably evolutionary contingencies and strongly conservative body plans within organism groups.
The following is multiple choice question (with options) to answer.
What are the only amphibians without legs? | [
"newts",
"porifera",
"caecilians",
"crustaceans"
] | C | Caecilians The caecilian order is the amphibian order with the fewest species. Caecilians are closely related to salamanders. They have a long, worm-like body. They are the only amphibians without legs. Caecilians evolved from a four-legged ancestor but lost their legs later in their evolution. As adults, they often burrow into the soil. That’s one reason why Caecilians tend to be less well known than other amphibians. microcaecilia. |
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