source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-3944 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
In eukaryotes, the cell cycle consists of a long preparatory period, called __________ before undergoing cell division. | [
"outerphase",
"mitosis",
"interphase",
"metaphase"
] | C | 10.2 The Cell Cycle The cell cycle is an orderly sequence of events. Cells on the path to cell division proceed through a series of precisely timed and carefully regulated stages. In eukaryotes, the cell cycle consists of a long preparatory period, called interphase. Interphase is divided into G1, S, and G2 phases. The mitotic phase begins with karyokinesis (mitosis), which consists of five stages: prophase, prometaphase, metaphase, anaphase, and telophase. The final stage of the mitotic phase is cytokinesis, during which the cytoplasmic components of the daughter cells are separated either by an actin ring (animal cells) or by cell plate formation (plant cells). |
SciQ | SciQ-3945 | reaction-mechanism, energy, theoretical-chemistry, reaction-coordinate
An approach towards identifying dynamic effect without trajectories
Insights into dynamic effects
Bifurcating organic reactions
The entirety of Chapter 8 of his book is also dedicated to this topic.
Addendum: FWIW, as a chemical engineer, the (imperfect) analogy that I like to use is to liken the MEP to the 'reversible process' of thermodynamics:
Start at the beginning state
Take an infinitesimal step
Let the system infinitesimally relax
Repeat 2 & 3 until you reach the end state
As I (very approximately) understand it, irreversibility comes from changing the state of a system "too much, too fast", leading to net generation of entropy as the system relaxes back to the reversible pathway, and it's "kinetic energy" in a qualitative, generalized sense that allows the system to depart from the reversible path.
The following is multiple choice question (with options) to answer.
Some biochemical processes happen via sequences of reactions which are called what? | [
"mutations",
"synthesis",
"pathways",
"metabolism"
] | C | Many biochemical processes occur through sequences of reactions called pathways. The total energy released by many of these pathways is much more than the energy a cell could handle if it were all released in a single step. For example, the combustion of glucose in a single step would release enough energy to kill a cell. By using a series of smaller steps that release less energy per reaction, however, the cell can extract the maximum energy from glucose without being destroyed. Referring to Equation 5.30, calculate how many grams of glucose would need to be metabolized to raise the temperature of a liver cell from an average body 3. |
SciQ | SciQ-3946 | ocean, oceanography, wind, waves, ocean-currents
Taking 10 meters (one of the smallest values in mid-latitudes) for the surface and bottom boundary layer thicknesses, that implies that in water depths shallower than 20 m the two boundary layers overlap. In water depths shallower than that, the transport in the surface layer is no longer perpendicular to the wind direction. The momentum input into the water by the wind (wind stress) is affected by the presence of the bottom and it is directly dissipated by bottom friction. The mixing by the wind (and wave breaking near the surf zone) results in additional mixing through the water column and facilitating well-mixed water columns. Under these conditions the wind-induced currents extend all the way to the bottom with the direction of the flow being a function of bottom depth, wind direction, and bottom slope. The presence of wind-induced currents does not preclude the occurrence of flow in the opposite direction of the wind.
A fantastic article summarizing the different flow conditions under different wind and wave fields in shallow water depths is given in Lentz and Fewings (2012). (Reprint)
Additional factors to consider are:
The following is multiple choice question (with options) to answer.
Deep ocean currents are caused by differences in what property at the top and bottom? | [
"density",
"velocity",
"mass",
"diameter"
] | A | Currents also flow deep below the surface of the ocean. Deep currents are caused by differences in density at the top and bottom. Density is defined as the amount of mass per unit of volume. More dense water takes up less space than less dense water. It has the same mass but less volume. Water that is more dense sinks. Less dense water rises. What can make water more dense?. |
SciQ | SciQ-3947 | geology
Title: What is this? A sinkhole?
Lat., long.38.47491, 43.48882, in the vicinity of Van in Turkey
I saw this when hiking. I want to know what it is and what are the dangers it poses. Lots of people hike that area in spring and summer, villagers collect edible plants in the area and graze livestock there. This is most likely a small slump scar modified by later erosion. If you look at the feature from a different angle in Google Earth, you will see that it's not even circular. It's more of a teardrop-ey crescent Moon shape, with the concave part downslope from the convex part. The bottom edge and top edge used to match up before the slide.
The following is multiple choice question (with options) to answer.
What forms when a glacier scrapes a large hole in the ground? | [
"crater lake",
"glacial hill",
"underground cavern",
"glacial lake"
] | D | The depression that allows water to collect to form a lake may come about in a variety of ways. The Great Lakes, for example, are glacial lakes. A glacial lake forms when a glacier scrapes a large hole in the ground. When the glacier melts, the water fills the hole and forms a lake. A kettle lake forms in the sediment left by a glacier when a block of ice melts. Kettle lakes are found where continental glaciers once covered the land ( Figure ' below ). Over time lakes get water from rain, streams, and groundwater coming to the surface. |
SciQ | SciQ-3948 | respiration
Here is what happens at the molecular level.
The $\rm CN^-$ ions diffuse into the mitochondria. They have high affinity to the ferrous ion of the mitochondrial enzyme cytochrome c oxidase involved in the electron transport chain (ETC), one of the phases of cellular respiration where $\rm ATP$ is generated from $\rm NADH$ and $\rm FADH_2$. And it is this process that actually requires oxygen. The inhibited cytochrome c oxidase is of no good in transporting electrons, thus no $\rm ATP$ molecules are generated. The oxygen molecules waiting for those electrons remain empty handed resulting in the increase in the concentration of molecular oxygen. Remember, ETC occurs in almost all living cells except a few like RBC which get their major share of ATP from the highly inefficient anaerobic glycolysis. Also, $\rm ATP$ is the energy currency of our body and is required in a wide variety of bodily processes like osmotic balance, nerve impulse transmission, muscle contraction etc. With no $\rm ATP$ your heart and respiratory muscles can't contract, your medulla can't regulate breathing, your kidneys can't concentrate urine and the list goes on. Death is imminent if a high concentration of cyanide gets into your blood.
The symptoms of panic like tachypnea and tachycardia (that result due to low oxygen in blood) are not usually seen unless the victim himself knows he is poisoned. The end effects like cardiac and respiratory arrest, seizures and coma, however, are similar to those of suffocation.
For further read:
The Mechanism of Cyanide Intoxication and its Antagonism
The following is multiple choice question (with options) to answer.
What is needed to provide cells with the oxygen they need for cellular respiration? | [
"passive transport",
"gas exchange",
"photosynthesis",
"vascular tissue"
] | B | Gas exchange is needed to provide cells with the oxygen they need for cellular respiration. Cells cannot survive for long without oxygen. Gas exchange is also needed to carry away carbon dioxide waste. Some of the carbon dioxide in the blood dissolves to form carbonic acid, which keeps blood pH within a normal range. |
SciQ | SciQ-3949 | 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 magma cools slowly, what texture does it have? | [
"large squares",
"small circles",
"large gases",
"large crystals"
] | D | Texture indicates how the magma cooled. Magma that cools rapidly has small or no visible crystals. Magma that cools slowly has large crystals; reference the Table above for the type of rock, the amount of silica it has, and examples. |
SciQ | SciQ-3950 | 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.
The calvin cycle is the fancy name for the metabolic pathway that builds what? | [
"sugar",
"fats",
"proteins",
"carbohydrates"
] | A | 13.2.1 The Detailed Dark Reactions What the Dark Reactions Do: The dark reactions build sugar from carbon dioxide gas (CO2), water (H2O), and energy from ATP molecules that were charged up during the light reactions. The dark reactions occur in the stroma of a chloroplast. Dark reactions usually occur in the light, but they don't have to. They'll occur in the dark until the chloroplast's supply of ATP runs out (usually about 30 seconds). The Calvin Cycle: The Calvin Cycle is the fancy name for the metabolic pathway that builds sugar. This means that it involves a whole lot of chemical reactions, and it uses a lot of different enzymes to catalyze the reactions. Carbon dioxide gas is stable, therefore the bonds that hold the carbon and oxygen atoms are strong. Therefore it takes a lot of energy to break the bonds and separate the carbon atoms from the oxygen atoms. The energy needed to do this comes from ATP molecules. When inorganic carbon (like from CO2) is being added to an organic molecule (such as sugar), this is called carbon fixation. It takes 2 complete turns of the Calvin Cycle to make a glucose molecule. Some portions of this text is based on notes very generously donated by Paul Doerder, Ph. , of the Cleveland State University. The detailed portions are not provided by Dr. Doerder. How cells divide. |
SciQ | SciQ-3951 | inorganic-chemistry
Title: Zinc evaporation/toxicity at room temperature I have a (slightly embarrassing) question regarding zinc powder.
I have recently broken an old mercury thermometer, and read that I can handle the mercury with powdered zinc - so I've sprinkled some on my floor. Too much probably. It turned out that unfortunately the powder is then quite hard to get out of the particular material of my floor (wood). I got out as much as possible, but I think there's still some left. So now I'm wondering if there is some danger if having all that zinc laying around.
Thanks anybody for the answer :) Zinc will amalgamate with mercury, but whether that reduces the vapor pressure of mercury very much is debatable. At best, the increased volume of zinc amalgam and the ability to amalgamate with fine droplets of mercury would make it easier to clean up the mercury as amalgam.
It might be better to spread some sulfur dust (flowers of sulfur) over the area. The sulfur should react with the mercury and tie it up as sulfide, with very low vapor pressure. Sulfur powder (and possibly the HgS) might also be easier to clean up than zinc dust, because sulfur is more like ordinary dust than a dense metal dust.
BTW, I love mercury thermometers. And I hate it when I break them!
The following is multiple choice question (with options) to answer.
The use of mercury-based dental amalgam has gone under question in recent years because of concerns regarding what? | [
"the expense",
"the oxygen",
"the toxicity",
"the variability"
] | C | Perhaps the most familiar liquid-solid solution is dental amalgam, used to fill teeth when there is a cavity. Approximately 50% of the amalgam material is liquid mercury to which a powdered alloy of silver, tin and copper is added. Mercury is used because it binds well with the solid metal alloy. However, the use of mercury-based dental amalgam has gone under question in recent years because of concerns regarding the toxicity of mercury. |
SciQ | SciQ-3952 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
Where does much of the blood that enters the atria flow? | [
"ventricles",
"arteries",
"muscles",
"lungs"
] | A | |
SciQ | SciQ-3953 | electricity, electrons, voltage, batteries, electrochemistry
Title: How batteries create voltage? I am trying to have a more fundamental understanding of electricity and specifically what voltage is.
My memory of highschool physics was that a battery has an excess of electron on one terminal, and a shortage on the other. This explanation caused some confusion when I thought about batteries in series; why does two 1,5V batteries add to 3V.
If it is excess and shortage of electrons, created from a chemical reaction, that attract the electrons from cathode to anode, wouldn't the volt (J/C) be the same for a circuit with two batteris; every electron in the cathode has one void to fill in the anode?
Some reading lead me to see battery voltage as a measurement of how much energy per electron (J/C) the chemical reaction produces, and the number of reactions per second as the current (C/s). I know 1 coulomb is not 1 electron, and one reaction doesn't necessarily = 1 free electron, this is a rough picture in my mind.
Does this mean that it is the energy released from the reaction that is accelerating the electron a certain amount depending on the amount of energy, and how is it that two batteries accelerate the electron twice as much?
This is my first attempt at articulation my confusion, so I'm sorry that this is not as eloquent as it could be Voltage (up to a factor) is the work one electron can produce when travelling from anode ($-$) to cathode ($+$). Current is the number of electrons flowing.
The energy needed to do the work comes from the energy released when electron participates in the reaction happening at cathode. This is chemistry-specific, so one cell of a battery has usually a very specific voltage.
Now imagine what happens if you have two cells in series. When, electron travels from A2 to C1 it produces work $W$ and when it reaches $C1$ it releases energy $U$. But at the same time, it allows another electron to travel from $A1$ to $C2$ and release another chunk of energy $U$. So in the end, $W=U+U=2U$ and we say that two cells in series have twice as large voltage, meaning for every electron participating in outer current, there is now twice as many reactions.
The following is multiple choice question (with options) to answer.
Batteries produce voltage through what type of reaction? | [
"non-chemical",
"liquid",
"thermal",
"chemical"
] | D | Chemical cells are found in batteries. They produce voltage by means of chemical reactions. Chemical cells have two electrodes, which are strips of different materials, such as zinc and carbon. The electrodes are suspended in an electrolyte. This is a substance that contains free ions, which can carry electric current. The electrolyte may be either a paste, in which case the cell is called a dry cell, or a liquid, in which case the cell is called a wet cell. Flashlight batteries contain dry cells. Car batteries contain wet cells. |
SciQ | SciQ-3954 | coordinate
If you want the stars to move with the rotation of the Earth, then you would use LONGITUDE = RA*15 - THETA*15, where THETA is the sidereal time at Greenwich in decimal hours.
You should be aware that for the celestial sphere you look from the centre towards the inside of the surface of the sphere, while for geographical purposes you look from the outside (above) towards the spheroid (down). So if you project the stars on a globe like this, you will notice that the constellations will look inverted from what you're used to in star maps. If you find one of those old celestial globes, you will also see the inverted constellations. For instance on this image, you'll see Leo to the left of Virgo and Hercules, while on most star maps, Leo will be to the right.
If you want the constellations to look 'right' then you would need to use LONGITUDE = -RA*15 (mind the minus sign). But then you would also need to invert the rotation of the Earth as well.
The following is multiple choice question (with options) to answer.
A globe is the best way to make a map of what? | [
"solar system",
"a city",
"whole earth",
"a continent"
] | C | Earth is a sphere and so is a globe. A globe is the best way to make a map of the whole Earth. Because both the planet and a globe have curved surfaces, the sizes and shapes of countries are not distorted. Distances are true to scale. ( Figure below ). |
SciQ | SciQ-3955 | bond
Title: Is energy required to form bonds [phase change] My question is if any energy is required to form bonds, for instance when there is a phase change?
If I am correct, energy might be required in the beginning, to make the reaction start and then release a bigger amount of energy than it was putted in. However, in terms of molecular behaviour in a phase change, I think there should not be any energy required to make the molecules to form bonds, if they are placed in a system which has a lower temperature than the molecules. Would they not lose the kinetic energy after a specific time? Bond formation always lowers the energy of the system (or bond formation is a consequence of lower energy, take your pick.)
Indeed, you may have to add energy, because presumably certain bonds must break in order to rearrange the atoms.
Adding energy won't guarantee formation of much higher energy isomers, because the atoms have a large amount of kinetic energy, and so they can just as easily turn around and go back whence they came.
Sometimes the kinetic energy can be dissipated by solvent, collisions with inert gasses, etc. and then you may end up with a measurable quantity of the higher energy species.
The following is multiple choice question (with options) to answer.
Bond energy is an indication of the amount of energy needed for what to occur? | [
"photosynthesis",
"physical reaction only",
"chemical reaction",
"oxidation"
] | C | Bond energy is an indication of the amount of energy needed for a chemical reaction. |
SciQ | SciQ-3956 | human-biology, genetics, human-genetics
Title: Are all genetic disorders inherited? I know that genetic diseases such as cystic fibrosis are often passed down through generations and are therefore classified as genetic disorders, but if a mutation occurs spontaneously, which for example leads to cancer, is this then classified as a genetic disorder?
Are all genetic disorders inherited?
Not all individuals with a genetic disorder inherited that disorder. Some genetic disorders are caused by spontaneous mutations.
Is cancer a genetic disorder?
Yes. The seminal paper by Hanahan and Weinberg, the Hallmarks of Cancer, is a good place to go to get a sense of what we understand cancer to be. This paper is quite influential and has its own wikipedia page. These authors wrote an updated review in 2011. Re: your question as it relates to cancer, yes, genetic changes result in tumorigenesis. Cancer is a genetic disorder of cell populations. One can view cancer diagnosis and treatment from the framework of cancer as a metabolic disease, but this adds to, rather than subtracts from the framework of cancer as a genetic disease.
Are other diseases caused by spontaneous mutations genetic disorders?
Yes. Achondrodysplasia is one illuminating example. It is a form of dwarfism caused by a mutation in the FGFR3 gene. It does follow mendelian autosomal dominant inheritance patterns, but in 80% of cases, the mutation is, in fact, acquired spontaneously (that is, not present in either parent). As noted by @Eff in the comments, Down syndrome, Trisomy 21 (and other chromosomal abnormalities, e.g., Turner, Kleinfelter, Patau, Edwards) are other common examples.
The following is multiple choice question (with options) to answer.
What causes genetic disorders? | [
"proteins",
"mutations",
"parasites",
"pollution"
] | B | Sequencing the human genome has increased our knowledge of genetic disorders. These are diseases caused by mutations. They may be caused by single gene mutations or the failure of chromosomes to separate correctly during meiosis. |
SciQ | SciQ-3957 | meteor, meteor-shower
Title: How to calculate a meteor's entrance altitude to Earth's atmosphere? Also, in which altitude did fireball went thermal explosion? There is a example here of the process required. But basically you need observations of the track from two locations and then just perform some relatively simple trigonometric triangulation. The Nemetode network regularly does this using images from a network of cctv cameras.
The following is multiple choice question (with options) to answer.
Located above the stratosphere, what layer is the place where meteors burn up? | [
"troposphere",
"mesosphere",
"unisphere",
"atmosphere"
] | B | The mesosphere is the layer above the stratosphere. Temperature decreases with altitude in this layer. Meteors burn up here. |
SciQ | SciQ-3958 | 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.
What composition determines both eruption type and volcano type? | [
"gas",
"chemical",
"electrical",
"magma"
] | D | Magma composition determines both eruption type and volcano type. |
SciQ | SciQ-3959 | genetics, homework
Title: law of independent assortment Self fetilization of F1 dihybrids, following independent assortment of alleles result in:
a) 3/16 Tall-rounds ; 3/16 dwarf-wrinkled
b) 9/16 Tall-wrinkled ; 3/16 dwarf-round
c) 9/16 Tall-round ; 3/16 dwarf-round
d) 3/16 Tall-wrinkled ; 3/16 dwarf-round
This question was asked in MCAT exam in Pak for which I'm preparing this year.... no genetic arcitecture was mentioned in question... The above mentioned is original format of question.... in ans-key, the ans is D but I am confused why it can't be C. In real life, round and tall are dominant traits in pea plants, which would make C and D both correct. I don't think people are expected to memorize the traits of pea plants, so the question ought to tell you somewhere which traits are dominant. There must be an error in the question as printed.
The following is multiple choice question (with options) to answer.
In a pedigree what shape symbolizes males? | [
"rectangles",
"spheres",
"squares",
"triangles"
] | C | In a pedigree, squares symbolize males, and circles represent females. A horizontal line joining a male and female indicates that the couple had offspring. Vertical lines indicate offspring which are listed left to right, in order of birth. Shading of the circle or square indicates an individual who has the trait being traced. The inheritance of the recessive trait is being traced. A is the dominant allele and a is recessive. An "affected" individual has the trait or characteristic (or disease) in question. |
SciQ | SciQ-3960 | sequence-alignment, phylogenetics, genome, phylogeny
Title: What is the most appropriate way to find the most recent common ancestor between two distantly related species I want to specifically find the common ancestor between a lobster and a humans. I suspect it was an aquatic worm of some description. But I want to know about the nervous system of this common ancestor. Because I've now posted several comments, I'll just roll them all up.
For background on the approaches used to identify most recent common ancestors and a high-level look at how animal taxonomy has been inferred, I suggest Lynch 1999.
I think that there are 2 interpretations of this question. If you are interested in just looking up a single MRCA of well-defined clades, such as lobster and human, here are some approaches:
Easy way:
Look at a tree diagram, e.g. this:
Find the tips that correspond to your species of interest (arthropods for lobster, chordata for humans).
Find where they join together in the diagram (the branch labeled "true coelom").
You have your answer, the MRCA is the group of organisms with a true coelom, coelomates.
A more involved way using a database
Go to this website.
Find the group of species 1 (arthropods, protostomes, etc. for lobster, chordata, deuterostomes etc. for human)
navigate around until you see the group containing the two groups (in this case listed as "bilateria"). In this case you are looking for the bilaterian common ancestor.
another database
Go to this website.
Point and click your way to a view where you see your 2 clades of interest (arthropods, chordates in this case). See figure.
Find where they join (in this case, it is less certain about the existence of a coelomate common ancestor, so it just says "bilaterians").
The following is multiple choice question (with options) to answer.
Mollusks are probably most closely related to organisms in the phylum annelida , also known as what? | [
"elongated worms",
"segmented worms",
"sedimentary worms",
"indigenous worms"
] | B | Mollusks are probably most closely related to organisms in the phylum Annelida , also known as segmented worms. This phylum includes the earthworm and leech. Scientists believe these two groups are related because, when they are in the early stage of development, they look very similar. Mollusks also share features of their organ systems with segmented worms. Unlike segmented worms, however, mollusks do not have body segmentation. The basic mollusk body shape is usually quite different as well. |
SciQ | SciQ-3961 | intermolecular-forces
Title: When is a dipole-dipole interaction strongest? Are there any conditions that'll improve the interaction? Just like, I assume, hydrogen bonds are strongest when the difference in electronegativity is biggest. To some degree, hydrogen bonding can be thought of as a subset or type of dipole-dipole interaction. This Wikipedia article defines dipole-dipole interactions as:
Dipole-dipole interactions are electrostatic interactions between permanent dipoles in molecules. These interactions tend to align the molecules to increase attraction (reducing potential energy).
The same article states, regarding hydrogen bonding:
The hydrogen bond is often described as a strong electrostatic dipole-dipole interaction. However, it also has some features of covalent bonding.
So, the assumption/example in your question is generally correct: just as a large difference in electronegativity of two atoms within a hydrogen bonding molecule results in stronger hydrogen bonds, the same tends to hold for non-hydrogen bonding dipole-dipole interactions. And while there are other forces affecting dipole-dipole interactions (i.e. solvent effects, molecular geometry/steric effects, etc.) it is the strength of the permanent dipole moment resulting primarily from the bond length and the difference in electronegativity between the atoms at the permanent dipole location that determine how strong the intermolecular dipole-dipole interactions will be.
The following is multiple choice question (with options) to answer.
Which bonds are the strongest of the intermolecular forces? | [
"complex",
"hydrogen",
"calcium",
"carbon"
] | B | As a solid is heated, its particles vibrate more rapidly as the solid absorbs kinetic energy. Eventually, the organization of the particles within the solid structure begins to break down and the solid starts to melt. The melting point is the temperature at which a solid changes into a liquid. At its melting point, the disruptive vibrations of the particles of the solid overcome the attractive forces operating within the solid. As with boiling points, the melting point of a solid is dependent on the strength of those attractive forces. Sodium chloride (NaCl) is an ionic compound that consists of a multitude of strong ionic bonds. Sodium chloride melts at 801°C. Ice (solid H 2 O) is a molecular compound whose molecules are held together by hydrogen bonds. Though hydrogen bonds are the strongest of the intermolecular forces, the strength of hydrogen bonds is much less than that of ionic bonds. The melting point of ice is 0°C. |
SciQ | SciQ-3962 | botany, microbiology, terminology, etymology
Title: Rhizosphere vs. Endorhiza? In relation to microbiology and the naming of the various areas of the plant as it relates to microbial inhabitance, I am confused as to the difference between the terms endorhiza and rhizosphere.
In this case I see rhizosphere referred simply to as the 'roots', but in this case I also see endorhiza explained simply as 'roots' also.
However in this case, I see a further explanation for endorhiza (which does make sense etymologically): 'internal root tissues'.
Does this mean endorhiza is be a sub-term for the area inside the roots, and the larger area of the rhizome in general represented by rhizosphere, and that is the difference? Healthy plant growth depends on a microbial community that lives around and inside the roots of plants (Bais et al. 2001). Roots secrete from the roots a number of chemical compounds that influences the microbial community around but outside of the roots. The microbial community can include bacteria, fungi, and single-celled parasites, as well as larger organisms like insect larvae and even roots from other plants. Some chemicals attract certain organisms while other chemicals repel organisms. This community of organisms around the roots is called the rhizosphere (Walker et al. 2003). The paper by Walker (open access) describes some of the many types of symbiotic relationships that occur in the rhizosphere.
Endorhiza refers to the internal environment of the root system. The endorhiza contains another microbial community of bacteria and fungi (Backman and Sikora 2008). The organisms of this endorhizal community are collectively called endophytes. Like the rhizosphere, the organisms in the endorhiza are important symbiotic species that benefit the health of the plant.
Similar communities have been identified for other regions of the plant, such as the phyllosphere, the organisms that live on the leaves, stems and other plant parts above the ground (Backman and Sikora 2008).
The following is multiple choice question (with options) to answer.
The community of all of the living and nonliving parts of an environment is known as what? | [
"biodiversity",
"ecosystem",
"population",
"habitat"
] | B | |
SciQ | SciQ-3963 | exoplanet
It's probably possible to have volcanic eruptions even though dozens or maybe even hundreds of miles of exotic ice because the heat has to go somewhere, eventually, assing it's likely to build up over time, so either by circulation of eruption, the heat has push through at some point. This even happens on so called "dead" planets like Mars or even the Moon. Mars still has the occasional volcanic eruption, just not very often.
But water worlds certainly can have plate tectonics. There's nothing in the water that would prevent it from happening. Plate Tectonics is, as I understand it, primarily a factor of the size of the planet. Gas planets - different story, but planets with a hard surface, Earth sized, a tiny bit smaller to a fair bit but not much bigger are good candidates for plate tectonics (I think). There's some debate on how large, I think, still going on. But I remember reading that ocean/water worlds might even be more likely to have plate tectonics. Plate tectonics is definitely something we'd look for if we ever get a close enough look at other planets in different solar-systems (exoplanets).
Just my thoughts on this. Not meant to be complete or definitive.
The following is multiple choice question (with options) to answer.
What is the most common type of volcano? | [
"geyser",
"cinder cone",
"block cone",
"flat"
] | B | Cinder cones are the smallest and most common type of volcano. Cinder cones have steep sides like composite volcanoes. But they are much smaller, rarely reaching even 300 meters in height. Cinder cones usually have a crater at the summit. Cinder cones are composed of small fragments of rock, called cinders. The cinders are piled on top of one another. The cinders can be mafic, intermediate, or felsic in composition. These volcanoes usually do not produce streams of lava. Cinder cones often form near larger volcanoes. Most composite and shield volcanoes have nearby cinder cones. |
SciQ | SciQ-3964 | thermodynamics, heat-engine, carnot-cycle
Title: Efficiency of heat engines I have been taught that the an engine running on the Carnot's cycle has the maximum efficiency among any other engine cycle, however I never found a convincing proof for it. Wherever I have put this question up, everyone just said pit it up against any engine and it will come out with a higher efficiency.
I would like to know if there is any way to prove mathematically that the Carnot's cycle has the maximum efficiency among any cycle?
Also, I have the belief that the second law of thermodynamics is a consequence of the fact that the Carnot's cycle has the maximum efficiency among any cycle. Because the Carnot's cycle has come before the second law of thermodynamics, I suppose that the former points to the latter. Is it actually true that the second law of thermodynamics comes from Carnot's theorem, and is it possible to prove that a Carnot's cycle would have the maximum efficiency for a particular amount of heat given in? Assuming you mean maximum efficiency when you say maximum energy, then the proof is by contradiction. Essentially, in order for a heat engine to be more efficient than a Carnot engine it would have to violate the second law of thermodynamics. Rather than for me to give you that proof, you can see it for yourself in the following link:
https://en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29
Hope this helps.
The following is multiple choice question (with options) to answer.
What is the name of the the most efficient possible engine? | [
"ventilation engine",
"excitation engine",
"diesel engine",
"carnot engine"
] | D | An ideal engine, the most efficient theoretically possible, is called a Carnot Engine. Its efficiency is given by the following formula, where the temperatures are, respectively, the temperature of the exhaust environment and the temperature of the heat input, in Kelvins. In a Carnot engine heat is input and exhausted in isothermal cycles, and the efficiency is . In all real engines heat is lost to the environment, thus the ideal efficiency is never even close to being obtained. |
SciQ | SciQ-3965 | energy, fuel, environmental-chemistry
Title: Effect of coal and natural gas burning on particulate matter pollution I sometimes hear people talking about how we should replace coal burning plants with natural gas ones, to alleviate the case of particulate matter pollution. What exactly is the difference between coal fuel and natural gas that makes the latter seem "cleaner"?
At the same energy outcome, natural gas produces less carbon dioxide than coal. In a way, natural gas is half way between coal and hydrogen.
Coal produces smelly smoke, solid particles, sulfur dioxide and minor or trace heavy metal pollutants.
It is less known to common people, but power plants burning coal are more significant source of radioactive pollution than nuclear plants. This pollution is very diluted, but rather significant in absolute amount. Coal ash, used in past as a filler for some construction materials, has lead in some cases to significantly increased content of radium-226 in building walls. This radium is a product of long term decay of natural uranium. It further decays while producing radioactive gaseous radon-222, which is dangerous in long term inhalation because of lung cancer. As it stays in lungs as polonium-218 and its decay products.
See e.g. Uranium produced from coal ash
... the uranium concentration in the ash pile is about 150-180 parts per million, about 1/4th of the concentration often thought of as commercially viable for ISL[In Situ Leaching] mining. However, coal ash piles have some physical characteristics that might help overcome that disadvantage since they may be easier to drill and it might be easier to protect the local groundwater from contamination. ...
See Radon in building materials by Czech government agency for radiation protection.
The following is multiple choice question (with options) to answer.
Carbon monoxide, radon gas, dust and pet dander are sources of what kind of pollution? | [
"light pollution",
"indoor air pollution",
"noise pollution",
"sound pollution"
] | B | One source of indoor air pollution is radon gas. Radon is a radioactive gas that may seep into buildings from rocks underground. Exposure to radon gas may cause lung cancer. Another potential poison in indoor air is carbon monoxide. It may be released by faulty or poorly vented furnaces or other fuel-burning appliances. Indoor furniture, carpets, and paints may release toxic compounds into the air as well. Other possible sources of indoor air pollution include dust, mold, and pet dander. |
SciQ | SciQ-3966 | thermodynamics, material-science, phase-transition, states-of-matter
Title: Why does matter exist in 3 states (liquids, solid, gas)? Why does matter on the earth exist in three states? Why cannot all matter exist in only one state (i.e. solid/liquid/gas)? The premise is wrong. Not all materials exist in exactly three different states; this is just the simplest schema and is applicable for some simple molecular or ionic substances.
Let's picture what happens to a substance if you start at low temperature, and add ever more heat.
Solid
At very low temperatures, there is virtually no thermal motion that prevents the molecules sticking together. And they stick together because of various forces (the simplest: opposite-charged ions attract each other electrostatically). If you picture this with something like lots of small magnets, it's evident enough that you get a solid phase, i.e. a rigid structure where nothing moves.
Actually though:
Helium won't freeze at any temperature: its ground state in the low-temperature limit at atmospheric pressure is a superfluid. The reason is that microscopically, matter does not behave like discrete magnets or something, but according to quantum mechanics.
There is generally not just one solid state. In the magnet analogy, you can build completely different structures from the same components. Likewise, what we just call “ice” is actually just one possible crystal structure for solid water, more precisely called Ice Ih. There are quite a lot of other solid phases.
Liquid
Now, if you increase temperature, that's like thoroughly vibrating your magnet sculpture. Because these bonds aren't infinitely strong, some of them will release every once in a while, allowing the whole to deform without actually falling apart. This is something like a liquid state.
Actually though:
The following is multiple choice question (with options) to answer.
What is the cause of existence of molecular solids and liquids? | [
"few forces",
"popular forces",
"negative forces",
"attractive forces"
] | D | |
SciQ | SciQ-3967 | virology, infection
Title: Why don't viruses cause wounds? A simple mental model of a viral infection is that an infected cell emits a lot of virions and eventually dies. The emitted virions have a chance of infecting other cells. Nearby cells are at a higher risk of infection.
Based on this model, if one cell in my nose gets infected, I would expect a large part of my nose to be destroyed, as the infection spreads and destroys more and more cells in the same area.
This does not happen! I survived a number of infections and still have my nose. Why?
I know there are "flesh eating" bacteria. Why isn't this the norm for infections? Does a common cold virus or SARS-CoV-2 not infect a lot of cells within the same area? A virus does not destroy that many cells before it is exterminated by the immune system or before the host dies.
Perhaps even more crucially, viruses typically target a very specific type of cell — those on the inner mucal surface of the nose in the case of cold or flu, those of the gastrointestinal tract in the case of stomach viruses, CD4 immune cells in the case of HIV, etc.
Update
As an example of how much time it takes for a virus to eat a noticeable wound, one could take the extermination of the immune cells by HIV - although it does not look as a physical wound, it is one, in the sense that enough of the specific tissue is destroyed to cause a life-threatening condition. It takes about a decade(!) - from the initial infection to the immune system failure.
On the other hand, the lethal effect of typical respiratory viruses is typically via obstructions of the respiratory ways due to inflammation or secretions resulting from the immune response, or via creating suitable conditions for a more serious bacterial infection.
The following is multiple choice question (with options) to answer.
Meningitis, for example, is caused by a viral or bacterial infection of the tissues covering what? | [
"the brain",
"the skin",
"the liver",
"the lungs"
] | A | Nervous tissue may become infected by microorganisms. Meningitis, for example, is caused by a viral or bacterial infection of the tissues covering the brain. This may cause the brain to swell and lead to brain damage and death. |
SciQ | SciQ-3968 | human-biology, endocrinology, organs
Title: Is there a blood panel lab test that measures all the hormone-producing glands? I understand that there are gland-specific hormone tests, such as:
Secretin: for the pancreas; and
Prolactin/ACTH: for the pituitary; and
PTH: for the payathyroid, etc.
However, are there any "composite" blood panels that test the "entire gamut/spectrum" of organs/glands, similar to what composite metabolic panels do for your cell counts? There are no composite tests that measure all the clinically important hormone producing glands. There are too many hormones produced by too many hormone producing cells/tissues in the body to test for all of them all at once (i.e. in a panel).
For illustrative purposes only... if you go to wikipedia they have a list of all hormones in the human body which is definitely far from complete! But it gives you an indication of just "how many" hormones there are and why testing for all of them is impossible in a panel.
Even with regard only to pancreatic hormones, there are several hormones produced (e.g. insulin, glucagon, somatostatin) that aren't necessarily a marker of the glands overall function (because they are not necessarily involved in the same function). Each of these hormones has different functions even though they are produced by the same gland.
Regardless, from a medical perspective you would never have a reason to test for all of them anyway. If you tested enough of them you'd find at least one of them that would - by chance - be abnormal.
Additionally, if you asked a handful of scientists to name fifty hormones there would be a lot of different hormones on each of their lists. The definition of hormone is vague, and we are learning more about new hormones every day. In the last decade we have learned that bile acids - chemicals predominately produced by the liver that are involved in dietary fat absorption - also act as hormones. There aren't clinical reasons to study all of these molecules just yet, but this demonstrates that it would be impossible to measure all of them all at the same time in one particular "panel".
The following is multiple choice question (with options) to answer.
What doctors specialize in diseases stemming from glandular issues? | [
"dermatologists",
"endocrinologists",
"oncologists",
"anthropologists"
] | B | Endocrinologist An endocrinologist is a medical doctor who specializes in treating disorders of the endocrine glands, hormone systems, and glucose and lipid metabolic pathways. An endocrine surgeon specializes in the surgical treatment of endocrine diseases and glands. Some of the diseases that are managed by endocrinologists: disorders of the pancreas (diabetes mellitus), disorders of the pituitary (gigantism, acromegaly, and pituitary dwarfism), disorders of the thyroid gland (goiter and Graves’ disease), and disorders of the adrenal glands (Cushing’s disease and Addison’s disease). Endocrinologists are required to assess patients and diagnose endocrine disorders through extensive use of laboratory tests. Many endocrine diseases are diagnosed using tests that stimulate or suppress endocrine organ functioning. Blood samples are then drawn to determine the effect of stimulating or suppressing an endocrine organ on the production of hormones. For example, to diagnose diabetes mellitus, patients are required to fast for 12 to 24 hours. They are then given a sugary drink, which stimulates the pancreas to produce insulin to decrease blood glucose levels. A blood sample is taken one to two hours after the sugar drink is consumed. If the pancreas is functioning properly, the blood glucose level will be within a normal range. Another example is the A1C test, which can be performed during blood screening. The A1C test measures average blood glucose levels over the past two to three months by examining how well the blood glucose is being managed over a long time. Once a disease has been diagnosed, endocrinologists can prescribe lifestyle changes and/or medications to treat the disease. Some cases of diabetes mellitus can be managed by exercise, weight loss, and a healthy diet; in other cases, medications may be required to enhance insulin release. If the disease cannot be controlled by these means, the endocrinologist may prescribe insulin injections. In addition to clinical practice, endocrinologists may also be involved in primary research and development activities. For example, ongoing islet transplant research is investigating how healthy pancreas islet cells may be transplanted into diabetic patients. Successful islet transplants may allow patients to stop taking insulin injections. |
SciQ | SciQ-3969 | entomology, parasitology, parasitism
The male (microgametocytes) and female (macrogametocytes) gametocytes are ingested by a female Anopheles mosquito during a blood meal (8) - only female mosquitoes (of pretty much any species) drink blood. The parasites' multiplication in the mosquito is known as the sporogonic cycle (stage C). While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes (9). The zygotes in turn become motile and elongated (ookinetes) (10) which invade the midgut wall of the mosquito where they develop into oocysts (11). The oocysts grow, rupture, and release sporozoites (12), which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle (1).
Sources
The following is multiple choice question (with options) to answer.
_________ are one-celled organisms with a nucleus which cause diseases such as malaria. | [
"mosquitos",
"fungi",
"protozoa",
"larvae"
] | C | Protozoa are one-celled organisms with a nucleus, making them eukaryotic organisms. They cause diseases such as malaria. Malaria is a serious disease that is common in warm climates. The protozoa infect people when they are bit by a mosquito. More than a million people die of malaria each year. Other protozoa cause diarrhea. An example is Giardia lamblia ( Figure below ). |
SciQ | SciQ-3970 | biochemistry, biophysics, bioenergetics
Title: Are there known life forms that are able to transform mechanical energy into chemical energy? Are there known life forms that are able to transform mechanical energy into chemical energy?
This question asks a similar subject, but more specific and has no answers.
The background of this question are thoughts about hypothetical life on tidally locked exoplanets of red dwarf stars, where light for photosynthesis is scarce but mechanical energy (storms and/or water currents) aplenty. There are no known life forms that use mechanical energy as a primary form of metabolic energy (i.e., for generic cellular functions). Many life forms are sensitive to mechanical disruption in some way, so they do utilize mechanical energy, but in a very limited fashion (@David's answer touches on this), and of course many organisms have life cycles that somehow depend on mechanical transportation (seed/spore dispersal, traveling on the wind or ocean currents, etc).
I think the main physical problem is that mechanical energy just isn't available to biological cells in a form that can be converted to substantial chemical energy. They are small, and tend to have other great benefits for being small.
To use an ocean wave as an example, there is very little or no perceptible movement for a cell in that wave, besides an apparent increase and decrease in the force of gravity. The top and bottom of the cell are moving together with the flow of water, so there is no differential to operate on.
An E. coli weighs about 1 picogram. If it could capture all of the energy from falling from 1km in the air on earth, assuming no uncaptured aerodynamic drag, that would be about 10-11 joules.
If there are ~3000 kJ/mol of energy available from burning glucose, that means about 5 × 10-21 joules per molecule of glucose, so about 20 billion glucose molecules, which sounds like a lot but it is only 1 femtogram, 0.1% the weight of the cell.
The following is multiple choice question (with options) to answer.
Chemical energy is another form of which energy? | [
"mechanical energy",
"nuclear energy",
"heat energy",
"potential energy"
] | D | Chemical energy and nuclear energy are other forms of potential energy. |
SciQ | SciQ-3971 | 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.
Many species secrete a hard external skeleton of what? | [
"sodium bicarbonate",
"calcium carbonate",
"hydrogen carbonate",
"carbon dioxide"
] | B | |
SciQ | SciQ-3972 | point, you may not quite understand what we mean by spread or variation. If we have two sets of observations. Measures of dispersion provide a more complete picture. Section 1 develops measures of investment return which are used in the study. Measures of dispersion between forecasters for economic variables can also proxy for economic uncertainty (Figure 4). Measures of Dispersion General Classifications of Measures of Dispersion (page 232) Measures of Absolute Dispersion A measure of absolute dispersion has the same unit as the observations. Measures of Central Location and Dispersion As epidemiologists, we use a variety of methods to summarize data. They give the answers in the same units as the units of the original observations. 12 The measure of dispersion which uses only two observations is called: (a) Range (b) Quartile deviation (c) Mean deviation (d) Standard. url?scp=34249938123&partnerID=8YFLogxK. Rigidly Defined: A good measure of dispersion should be properly and rigidly defined so that it does not create any problem for the reader in analysing the data. Measures of Dispersion The central values i. 5 m thick, 180-m wavelength for ice 0. Two well-known examples are the standard deviation and the interquartile range. 75 m thick, and 200-m wavelength for ice 1 m thick. It's quite useful. There are a variety of income dispersion/variance measures, but they all show the same basic pattern: U. The coefficient of variation is the standard deviation divided by the mean. And let's compare it to this data set over here. A measure of dispersion is used to quantify the size of the differences of a variable. Which measure of central tendency best represents the data?. The principles of clinical psychology rely on averages and norms based on long-term studies and trends that practicing psychologists and researchers have documented and published. In this lesson, you'll learn about the different measures of dispersion and explore how they are related to each other as well as other summary statistics. The measures of dispersion are: Range. The measure of dispersion depending upon the lower and upper quartiles is know as the quartile deviation. _____ is defined as the difference between the smallest and. There are two
The following is multiple choice question (with options) to answer.
What is the most common pattern of dispersion? | [
"clumped",
"uniform",
"sporadic",
"random"
] | A | |
SciQ | SciQ-3973 | water, atmospheric-science, molecules, humidity
Commentary 3: Physics explanation based on molecule movement will be greatly appreciated. While you are at it - I have a hypothesis why humidity of the atmosphere is seldom 100 %. Water molecules are lighter than nitrogen (or average air) molecules and thus water vapour rises upward due to buoyancy. Depending on the temperature and vicinity of open water surfaces, the rate at which water molecules float upward may be faster than the rate of evaporation, resulting in a temporary steady state where relative humidity is below 100 %. The water vapour in the atmosphere is not lost to the space, however. At some point it cools down so much that it condenses. Thus clouds are made, which float until they can't support their own weight (by whatever means, up-drafts, buoyancy...) at which point the liquid water obeys gravity and falls down again. This greatly enhances evaporation rates while cooling the atmosphere down, and thus relative humidity rises to near 100 % while it's raining. Once the rain is done and the excess water is either absorbed or evaporates again, the cycle starts up again. Water molecules are lost to the upper layers of the atmosphere faster than evaporation can supply them, and thus relative humidity falls below 100 % again. How far below depends on the temperature, major air currents, open bodies of water, and so on. With neither evaporation nor condensation is the system then you can regard the water vapor and the dry air as distinct systems each subject to the same boundary conditions and conclude that they will have the same behavior.
Thus the absolute fraction of water will be the same at both ends and the relative humidity will vary.
The following is multiple choice question (with options) to answer.
Water droplets form when the air reaches 100-percent what? | [
"humidity",
"density",
"chance of rain",
"heat"
] | A | Water droplets form when the air reaches 100% humidity. If the temperature is cold enough, frost will form. |
SciQ | SciQ-3974 | organic-chemistry, nomenclature, carbonyl-compounds, cyclohexane
From there, I imagine you can figure out the rest: the cyclohexane as a valid chain is also the longest chain, you start numbering from the functional group, etc. Hope that helped explain the teacher's answer!
The following is multiple choice question (with options) to answer.
Any large molecule is referred to as what? | [
"microtubule",
"polymer",
"cellular",
"macromolecule"
] | D | Carbon’s affinity for covalent bonding means that many distinct and relatively stable organic molecules nevertheless readily form larger, more complex molecules. Any large molecule is referred to as macromolecule (macro- = “large”), and the organic compounds in this section all fit this description. However, some macromolecules are made up of several “copies” of single units called monomer (mono- = “one”; -mer = “part”). Like beads in a long necklace, these monomers link by covalent bonds to form long polymers (poly- = “many”). There are many examples of monomers and polymers among the organic compounds. Monomers form polymers by engaging in dehydration synthesis (see Figure 2.14). As was noted earlier, this reaction results in the release of a molecule of water. Each monomer contributes: One gives up a hydrogen atom and the other gives up a hydroxyl group. Polymers are split into monomers by hydrolysis (-lysis = “rupture”). The bonds between their monomers are broken, via the donation of a molecule of water, which contributes a hydrogen atom to one monomer and a hydroxyl group to the other. |
SciQ | SciQ-3975 | geology, rocks, sedimentology, geomorphology, terminology
Title: What do you call boulders of non sedimentary rock that were lithified into sandstone? I'm convinced there is a word for this. I was in the Hoodoos at Writing on Stone this weekend and kept noticing what looked like reddish quartzite boulders laying around in the sand, or sometimes sticking partially out of the hoodoos.
When a non-sedimentary rock gets washed out into silt which later lithifies, what's it called? It's kind of like a conglomerate, except there's only a couple of really big rocks, which eventually fall out out the rock because all the sandstone around them eroded away. The technical term for a sedimentary rock that has a lithified fine-grained sediment with larger pieces of rocks suspended in it upon lithification is a conglomerate. The fine-grained interstitial part is called the matrix, and the large pieces suspended in it are called clasts. Clasts can range from gravel- to boulder-size. These are technical terms used by sedimentologists.
It is tempting to refer to these fragments as xenoliths but as that word has a very specific meaning in igneous petrology, it is best to avoid it to remove any confusion.
The following is multiple choice question (with options) to answer.
The rocks that are taken from a mine are full of valuable minerals plus rock that isn't valuable. what is this rock called? | [
"waste rock",
"empty rock",
"garbage rock",
"compost rock"
] | A | Most minerals are a combination of metal and other elements. The rocks that are taken from a mine are full of valuable minerals plus rock that isn't valuable. This is called waste rock. The valuable minerals must be separated from the waste rock. One way to do this is with a chemical reaction. Chemicals are added to the ores at very high temperatures. |
SciQ | SciQ-3976 | ichthyology, homeostasis, osmoregulation
Pillans, R.D. and C.E. Franklin, 2004. Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient. Comparative Biochemistry and Physiology, Part A 138: 363-371.
The following is multiple choice question (with options) to answer.
Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as what? | [
"trichina",
"stenohaline",
"saline intolerant",
"antisaline"
] | B | Osmoregulators and Osmoconformers Persons lost at sea without any fresh water to drink are at risk of severe dehydration because the human body cannot adapt to drinking seawater, which is hypertonic in comparison to body fluids. Organisms such as goldfish that can tolerate only a relatively narrow range of salinity are referred to as stenohaline. About 90 percent of all bony fish are restricted to either freshwater or seawater. They are incapable of osmotic regulation in the opposite environment. It is possible, however, for a few fishes like salmon to spend part of their life in fresh water and part in sea water. Organisms like the salmon and molly that can tolerate a relatively wide range of salinity are referred to as euryhaline organisms. This is possible because some fish have evolved osmoregulatory mechanisms to survive in all kinds of aquatic environments. When they live in fresh water, their bodies tend to take up water because the environment is relatively hypotonic, as illustrated in Figure 41.3a. In such hypotonic environments, these fish do not drink much water. Instead, they pass a lot of very dilute urine, and they achieve electrolyte balance by active transport of salts through the gills. When they move to a hypertonic marine environment, these fish start drinking sea water; they excrete the excess salts through their gills and their urine, as illustrated in Figure 41.3b. Most marine invertebrates, on the other hand, may be isotonic with sea water ( osmoconformers). Their body fluid concentrations conform to changes in seawater concentration. Cartilaginous fishes’ salt composition of the blood is similar to bony fishes; however, the blood of sharks contains the organic compounds urea and trimethylamine oxide (TMAO). This does not mean that their electrolyte composition is similar to that of sea water. They achieve isotonicity with the sea by storing large concentrations of urea. These animals that secrete urea are called ureotelic animals. TMAO stabilizes proteins in the presence of high urea levels, preventing the disruption of peptide bonds that would occur in other. |
SciQ | SciQ-3977 | thermodynamics, energy, statistical-mechanics, temperature, water
What you're essentially asking for is the specific heat capacity of liquid water. Already this is ill-defined, because that depends on whether the volume or pressure is held constant, and is also temperature dependent:
source
Even if you specify that e.g. you're looking for the isobaric specific heat capacity at $T=10^\circ$ C, the calculation is highly non-trivial. Unlike an ideal gas, whose particles have no interactions whatsoever, the particles in a liquid are strongly interacting and possess both kinetic and potential energy. Water in particular is even more difficult to handle than usual because of the strong dipolar interactions which result from its large permanent electric dipole moment (i.e. hydrogen bonds).
If it's currently possible to get a good theoretical estimate of the specific heat capacity of water (based on the details of the H$_2$O molecule) then I don't know how to do it. This is far from my field, so I wouldn't be the person to ask. But it's certainly not the case that it could be trivially read off from a proportionality constant.
The following is multiple choice question (with options) to answer.
In a liquid, the particles are still in close contact, so liquids have a definite what? | [
"shape",
"growth",
"volume",
"weight"
] | C | Liquids If the particles of a substance have enough energy to partially overcome intermolecular interactions, then the particles can move about each other while remaining in contact. This describes the liquid state. In a liquid, the particles are still in close contact, so liquids have a definite volume. However, because the particles can move about each other rather freely, a liquid has no definite shape and takes a shape dictated by its container. |
SciQ | SciQ-3978 | thermal-radiation, heat-conduction, radiative-transfer
Title: Is thermal conduction really radiation? I have no doubt thermal conduction is a useful model for heat transfer, wherein kinetic energy is transferred between particles when they collide. However, according to explanations that I believe are canonical, two molecules collide due to electromagnetic repulsion (and possibly Pauli Exclusion) of their electron "clouds". In the standard model of particle physics, electromagnetic repulsions between electrons occur via the exchange of force-carrying particles, which happen to be photons. (Virtual photons, if I'm not mistaken, and perhaps that is an important point here.)
So, if thermal conduction is microscopic kinetic energy transfer due to molecular collisions, and molecular collisions occur by the exchange of photons, then it appears to me that at a fundamental level thermal conduction is a special case of energy transfer by photons, which in my understanding, is the radiation mechanism of heat transfer.
Is this conclusion incorrect (and if so, why)? The important distinction between thermal conduction and thermal radiation is that the heat exchange is driven by the difference in temperature for thermal conduction and the heat exchange is driven by the fourth power of the difference in temperature for thermal radiation. Perhaps it would be possible to derive, on a microscopic level, the relationship between this fourth-power microscopic radiation and the macroscopic first-power conduction equation. However, I am not aware of such a derivation and it is not immediately obvious. Certainly, even if such a microscopic derivation is possible, the macroscopic form is sufficiently different to warrant its own category
The following is multiple choice question (with options) to answer.
What is the transfer of thermal energy between particles of matter that are touching called? | [
"activation",
"radiation",
"convection",
"conduction"
] | D | Conduction is the transfer of thermal energy between particles of matter that are touching. Thermal conductors are materials that are good conductors of thermal energy. Thermal insulators are materials that are poor conductors of thermal energy. Both conductors and insulators have important uses. |
SciQ | SciQ-3979 | newtonian-mechanics, forces, everyday-life, biophysics, weight
All of this makes it very complicated because you need to isolate what type of stress is under consideration. However, we can make some general observations.
Any vertical position will maximize compressive stress on the backbone. So standing and sitting straight up should maximize compressive stress. Why sitting down is more than standing up is not clear. Perhaps it has to do with concentrated stress that the reaction force of the seat imposes on the bottom of the spine (tail bone). Or perhaps sitting down causes more curvature of the spine, though I’m not sure.
Any horizontal position will minimize compressive, tensile and bending stress. So lying down should be less “stressful” on the backbone than all the other positions.
Sitting and leaning over would probably be the most stressful since bending of the backbone is maximized. This results in both tensile and compressive stress on the backbone.
Hope this helps.
The following is multiple choice question (with options) to answer.
Regularly performing weight-bearing exercise can reduce the risk of what condition that affects bones? | [
"arthritis",
"marrow deficiency",
"osteoporosis",
"psoriasis"
] | C | Regular weight-bearing exercise can reduce the risk of osteoporosis. Apply lesson concepts to explain why. |
SciQ | SciQ-3980 | evolution
Title: Homologous structures under Lamarck I've read that Lamarck's theory doesn't explain homologous structures.
But, what about the following hypothetical under Lamarck's theories:
A population develops an adaptation to its environment
Part of the adapted population moves away
The adaptation is passed onto the population's offspring
All offspring of the original population have the adaptation, regardless of whether or not their ancestors moved away
Isn't this adaptation a homologous structure? I agree with you that I can't see why Lamarck's hypothesis could not explain the presence of homologous structures.
The link you offer also claim that Larmarck's hypothesis would fail to explain "Biogeographical diversity patterns". While this expression is a little vague, I would fail to understand why Lamarck's hypothesis would fail to explain patterns of biogeographical diversity.
The phrasing of your scenarios (absence of the term allopatric speciation, usage of the term "develops" instead of "evolves" of just "adapts") suggests that you may take advantage of an intro course to evolutionary biology such as the short and good course by UC Berkeley called Understanding Evolution
The following is multiple choice question (with options) to answer.
What do we call structures that have lost their use through evolution, which serve as important evidence of evolution? | [
"primordial",
"adaptative",
"vestigial",
"extinct"
] | C | Vestigial structures, or structures that have lost their use through evolution, are important evidence of evolution. |
SciQ | SciQ-3981 | energy-conservation, mass-energy
Title: Could we create energy by dropping object from above, obtain potential energy, mass to energy, transfer energy to sky, energy back to mass, repeat Imagine we drop a 1000 kg object from 5 km height. When it reaches the ground, we obtain potential energy. Then we convert the object (mass) into energy, we transfer the energy back to 5 km height (assuming no energy is lost) then we convert back the energy into mass, then we repeat the process. Drop the object, obtain potential energy, convert to energy, transfer it to 5 km height, convert it back to matter. I understand this is hypothetical since no technology we have today allow us to perform this. How conservation of mass-energy get along with this?
*Energy can actually be converted into matter
https://www.forbes.com/sites/paulrodgers/2014/05/19/einstein-was-right-you-can-turn-energy-into-matter/ I don't think conservation of mass and energy would have a problem with this, I believe you are missing a step, or misinterpreting how mass-energy equivalence manifests.
We start with a mass, drop it, and get potential energy from that. No problems here, that makes sense.
Then, you take that mass and turn it into energy; you acknowledge that it's theoretical; so I don't necessarily have a problem with this step.
It's the next step where things get a little sticky I believe. You say:
we transfer the energy back to 5 km height (assuming no energy is lost)
Now, I can even get behind the fact that you don't lose any of the energy (the equivalent amount as the $1000 \ kg$ mass); but what I can't get behind is how you move that energy up there.
What type of energy is this; and what are you using to move it against gravity?
Basically, you would not be able to freely move all that energy to the $5 \ km$ point without putting the energy needed in to raise the equivalent mass to that location. Consider, in theory that you had a device that could contain all this energy in some non-mass form. It wouldn't matter. The result would be the container weighing the same as if that were a mass itself (assuming a perfect container; which is necessary for the no energy loss condition).
The following is multiple choice question (with options) to answer.
What is the only way of transferring energy that doesn't require matter? | [
"mutation",
"radiation",
"evaporation",
"convection"
] | B | Both conduction and convection transfer energy through matter. Radiation is the only way of transferring energy that doesn’t require matter. Radiation is the transfer of energy by waves that can travel through empty space. When the waves reach objects, they transfer energy to the objects, causing them to warm up. This is how the sun’s energy reaches Earth and heats its surface (see Figure below ). Radiation is also how thermal energy from a campfire warms people nearby. You might be surprised to learn that all objects radiate thermal energy, including people. In fact, when a room is full of people, it may feel noticeably warmer because of all the thermal energy the people radiate! To learn more about thermal radiation, watch "Radiation" at the URL below. |
SciQ | SciQ-3982 | atmosphere, clouds, thermodynamics, air-currents
Title: Elevation of Atmosphere differ? Does the atmosphere depth (or how high the air molecules from the ground) of Earth or Mars differ gradually or can there be plumes of atmosphere that reaches into space? If I were able to travel a perfect circle around the equator would the atmosphere differ in elevation? The atmosphere, as a whole, is approximately in hydrostatic equilibrium. This means that the gravity of the earth holds the atmosphere to the earth, preventing its escape, though few molecules may escape every so often.
Mathematically, this can be described by $$\frac{dP}{dr}=-\rho g$$ where P is the pressure, $\rho$ is the density, and $g$ is gravity. Using the Ideal Gas Law $$P=\rho R T$$, where $T$ is temperature and $R$ is the gas constant for air. Assuming that the temperature in the height of a column of the atmosphere is averaged ($\bar{T}$) an equation for the average height of the atmosphere can be found $$P(r,\phi,\lambda)=P_0(\phi,\lambda)exp(-\frac{(r-r_0)g}{R\bar{T}(\phi,\lambda)})=P_0(\phi,\lambda)exp(-\frac{gz}{R\bar{T}(\phi,\lambda)})$$
where $r_0$ is the radius of the earth,$P_0$ is the surface pressure, $r=z+r_0$, where $z$ is the height above the earth's surface, $\phi$ is the latitude, and $\lambda$ is the longitude.
To Summarize:
As the average temperature of the atmosphere increases, the height of the atmosphere will generally increase. This means that the height of the atmosphere will generally be the lowest near the poles, but highest near the equator. There are certainly exceptions to this rule, but this generally works. If you were to go around the equator, it will likely not be a "perfect circle" since the average temperature would have to be exactly the same.
The following is multiple choice question (with options) to answer.
The layers of the atmosphere correspond with what changes with altitude? | [
"nitrogen",
"oxygen",
"friction",
"temperature"
] | D | The atmosphere has layers. The layers correspond with how temperature changes with altitude. By understanding the way temperature changes with altitude, we can learn a lot about how the atmosphere works. |
SciQ | SciQ-3983 | organic-chemistry, mixtures
Title: Would Oxygen Gas and Ozone be a pure substance together? If I have oxygen gas and ozone ($\ce{O2 + O3}$) together would it be considered a pure substance or a mixture?
And would pure substances always have the same molecular structure? Ozone is highly reactive and unstable, while dioxygen is stable. There do not combine to form a compound. So, clearly it is a mixture.
To answer the second part of the question, "And would pure substances always have the same molecular structure?", first a Wikipedia definition on substances, to quote:
A chemical substance is a form of matter having constant chemical composition and characteristic properties.[1][2]...
Chemical substances can be simple substances[4], chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.[4]
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water...
However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of the chemical.
And further:
A chemical substance may well be defined as "any material with a definite chemical composition" in an introductory general chemistry textbook.[5] According to this definition a chemical substance can either be a pure chemical element or a pure chemical compound. But, there are exceptions to this definition; a pure substance can also be defined as a form of matter that has both definite composition and distinct properties.[6] The chemical substance index published by CAS also includes several alloys of uncertain composition.[7] Non-stoichiometric compounds are a special case (in inorganic chemistry) that violates the law of constant composition, and for them, it is sometimes difficult to draw the line between a mixture and a compound, as in the case of palladium hydride. Broader definitions of chemicals or chemical substances can be found, for example: "the term 'chemical substance' means any organic or inorganic substance of a particular molecular identity, including – (i) any combination of such substances occurring in whole or in part as a result of a chemical reaction or occurring in nature".[8]
The following is multiple choice question (with options) to answer.
What do you call a type of mixture that has the same composition throughout? | [
"solution",
"transfusion",
"structure",
"transition"
] | A | This giant Buddha statue, which is a national treasure in Japan, is made of bronze. Bronze consists mainly of copper but also contains some tin. Bronze is an example of a solution. A solution is a type of mixture that has the same composition throughout. |
SciQ | SciQ-3984 | 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.
What traits do the sponge and tarantula share? | [
"lack of backbone",
"lifespan",
"number of eyes",
"number of legs"
] | A | One trait invertebrates like the sponge and tarantula share is lack of a backbone. In fact, they don’t have any bones at all. These are defining traits of all invertebrates. Some invertebrates have a skeleton, but it isn’t made of bone. Many other traits of invertebrates show considerable diversity. |
SciQ | SciQ-3985 | 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.
Organisms are highly organized, coordinated structures that consist of one or more what? | [
"cells",
"lipids",
"nucleus",
"proteins"
] | A | Organisms are highly organized, coordinated structures that consist of one or more cells. Even very simple, single-celled organisms are remarkably complex: inside each cell, atoms make up molecules; these in turn make up cell organelles and other cellular inclusions. In multicellular organisms (Figure 1.10), similar cells form tissues. Tissues, in turn, collaborate to create organs (body structures with a distinct function). Organs work together to form organ systems. Sensitivity or Response to Stimuli. |
SciQ | SciQ-3986 | electric-circuits, voltage
Title: Unsatisfactory explanation for the EMF measurement of a battery Experimentally, I have seen how hooking up a battery to a simple circuit just with a high-resistance voltmeter raises the voltage reading (allegedly to a level equal to the EMF of the battery).
However, I find the explanation for why the reading rises, much less to an EMF, very unconvincing. We were told that the internal resistance and the necessary potential drop is ignored, because there is no current in the said circuit, hence why the voltmeter measures an EMF. How can this make sense? There clearly must be some current, albeit very little, flowing, for the high-resistance voltmeter to even have a reading, and that little current will still experience resistive forces from the internal resistance of the cell - so the EMF should not be attainable. Or is there a mechanism by which, when there is very little current, resistors are ignored, hence no work has to be done to traverse them?
Clearly I am wrong, as experimentally I saw the voltage rise in that super simple cell. My point of view suggests that there shouldn't be a difference between the reading in said circuit and the potential difference in a circuit consisting of 3 resistors (the voltmeter in this case measures the drop between these 3 resistors, note there is no other significant source of resistance other than the internal resistance). Really, in my theoretical understanding they should produce an equal reading, but they don't.
So, to be honest, not only do I believe that the reading we saw shouldn't have been the EMF, but not even any different from the reading in a normal circuit, as described (the latter belief clearly conflicts with reality).
I an eager to know what I am thinking wrongly about. Please ask if I can help clarify anything!
Thank you very much :)! You're quite correct that there will be some current flowing, so there must be a voltage drop due to the internal resistance of the battery. The EMF measured by any voltmeter will always be less than the true EMF.
If the internal resistance of the battery is $R_b$ and the resistance of your voltmeter is $R_m$ then the voltage you measure will be:
$$ V = \frac{R_m}{R_m + R_b} E $$
The following is multiple choice question (with options) to answer.
What do voltmeters measure? | [
"amplitude",
"frequency",
"temperature",
"voltage"
] | D | 21.4 DC Voltmeters and Ammeters • Voltmeters measure voltage, and ammeters measure current. • A voltmeter is placed in parallel with the voltage source to receive full voltage and must have a large resistance to limit its effect on the circuit. • An ammeter is placed in series to get the full current flowing through a branch and must have a small resistance to limit its effect on the circuit. • Both can be based on the combination of a resistor and a galvanometer, a device that gives an analog reading of current. • Standard voltmeters and ammeters alter the circuit being measured and are thus limited in accuracy. |
SciQ | SciQ-3987 | human-anatomy
Title: Why is a penis an organ? According to Wikipedia an "An organ is a group of tissues with similar functions". I don't know anything about anatomy but it doesn't seem to me that a penis can be delimited somewhere to form a "group". Therefore I do not understand why a penis is considered an organ.
Can you explain it to me ? Frankly, that's a terrible definition by Wikipedia.
Merriam-Webster defines an organ as:
a differentiated structure (such as a heart, kidney, leaf, or stem) consisting of cells and tissues and performing some specific function in an organism
or
bodily parts performing a function or cooperating in an activity
The important defining feature of an organ is not that the tissues have similar functions but that, together, the tissues comprise a functional whole that achieves some end goal.
For the penis, it consists of multiple tissues with different functions:
(from https://www.ncbi.nlm.nih.gov/books/NBK525966/figure/article-20668.image.f1/ - original from Gray's Anatomy)
The different tissues pictured here: the fibrous envelope, the corpora cavernosa, the septum pectiniforme, the urethra and blood vessels, the nervous tissue in the skin: all of these tissues have different individual functions: structural, erectile, carrying urine or semen, etc.
The key that unifies them into an organ is that the functions of the penis at the organism level (principally sexual function) are not served by any of these tissues alone, but rather by their combination in a full structure: an organ.
Ultimately, organ definitions are somewhat opinion-based: people are lumpers and splitters, so you might find conflicting definitions for which groupings of tissues reflect distinct organs, but I think by most standards you would find the penis to be considered a distinct organ, affiliated with but distinct from the primary sex organs and associated glands.
The following is multiple choice question (with options) to answer.
What is the term for body parts that do not serve their original function? | [
"abnormal structures",
"false structures",
"vestigial structures",
"amenable structures"
] | C | Moles live underground where they do not need eyes to find their way around. This mole’s eyes are covered by skin. Body parts that do not serve their original function are vestigial structures. |
SciQ | SciQ-3988 | ecology
Title: Statement about Tropical Rainforests I made a statement about tropical rainforests, and I want to know if it's somewhat true or not:
The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The reason that a tropical rainforest has a huge amount of vegetation is because of the quick mineralisation. If a dead leaf falls onto the ground, it immediately gets turned into minerals, which the plants immediately use for sustaining theirselves There are many websites which describe this phenomenon. They all seem to confirm the basic premise of the question: in tropical rain forests most of the minerals are held in the biomass and rapid decomposition contributes to the recycling of these nutrients for new growth. One example is here.
Tropical rainforests are noted for the rapid nutrient cycling that occurs on the ground. In the tropics, leaves fall and decompose rapidly. The roots of the trees are on the surface of the soil, and form a thick mat which absorbs the nutrients before they reach the soil (or before the rain can carry them away). The presence of roots on the surface is a common phenomenon in all mature forests; trees that come along later in succession win out in competition for nutrients by placing their roots over top of the competitors, and this pattern is seen in the temperate rainforest as well. What does not occur in the temperate rainforest, however, is a rapid cycling of nutrients. Because of the cold conditions and the acidity released by decomposing coniferous needles on the forest floor, decomposition is much slower. More of the nutrients are found in the soil here than would be the case in a tropical forest, although like the tropical forest most of the nutrients are held in the plants and animals themselves.
I looked for actual evidence of these differences in rates of decomposition and I found this:
Salinas, N. et al. (2011) The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests. New Phytologist 189: 967-977
The following is multiple choice question (with options) to answer.
The soil beneath a deciduous forest is called what? | [
"forest floor",
"trichina",
"cocklebur",
"pedalfer"
] | D | The soil beneath a deciduous forest is a pedalfer. These soils are very fertile. |
SciQ | SciQ-3989 | reaction-mechanism, stoichiometry, ionic-compounds
Title: What is the correct molecular, total ionic, and net ionic reaction equation of reaction between magnesium nitrate and sodium chromate? From the question, I think that the reactants are $$\ce{Mg(NO3)2(aq) + Na2CrO4(aq)}$$
But the problem is, I am confused about the result of the reaction. Is it $$\ce{MgCrO4}$$ and/or $$\ce{NaNO3}$$?
How is the state of the product? In my opinion, there should be at least $$\ce{NaNO3(aq)}$$ as the product, but what about the magnesium chromate? Is it really magnesium chromate or it is something else? There is no solvated molecule of either of 4 ionic compounds. All interactions ( or lack of ) happen on hydrated ionic level, including eventual precipitation or formation of ionic pairs.
All four salts are soluble, including magnesium chromate with the solubility $\pu{137 g/100 mL}$ at $\pu{20^{\circ}C}$ (solubility table).
When dissolved, salts form independent hydrated ions:
$\ce{Mg(NO3)2(s) + Na2CrO4(s) ->[H2O] Mg^2+(aq) + 2 NO3-(aq) + 2 Na+(aq) +CrO4^2-(aq)}$
If the solution is being evaporated, the salt with lowest solubility starts precipitating the first, with the repective ions recombining into the solid, stripping off their hydration cover.
The same solution is formed, if we start with equivalent amounts of the other two salts:
$\ce{2 NaNO3(s) + MgCrO4(s) ->[H2O] Mg^2+(aq) + 2 NO3-(aq) + 2 Na+(aq) +CrO4^2-(aq)}$
Ions have no memory which ions they were paired with in the solid state.
The following is multiple choice question (with options) to answer.
What is composed of a calcium cation and a nitrate anion? | [
"calcium nitrate",
"dynamite",
"calcium carbonate",
"nitrous oxide"
] | A | Writing a formula for a ternary ionic compound also involves the same steps as for a binary ionic compound. Write the symbol and charge of the cation followed by the symbol and charge of the anion. Use the crisscross method to ensure that the final formula is neutral. Calcium nitrate is composed of a calcium cation and a nitrate anion. |
SciQ | SciQ-3990 | dna, reproduction, dna-replication, dna-damage
cells basically create copies of DNA all the time in our body. ... Why does inbreeding cause genetic defects, but cell division in one's own body does not?
During normal cell division AaBB cells should produce only AaBB copies which have at least one functional copy A and B gene and thus are fine.
Big picture
In a real population imagine every individual has tens of thousands of genes and each of them can be made nonfunctional by random mutation. The nonfunctional copy often does not have effect since the individual has another functional copy. When two non-related individuals procreate, chances are mutations they carry are in different genes and their progeny are fine as illustrated above. When related individuals procreate chances are thay both have the same deterious mutation(s) and not all their progeny will be fine.
But bed bugs for instance, have managed with inbreeding without any problem (goddamned creatures!).
Species for which inbreeding is normal have much less recessive deleterious mutations prevalence in populations for simple reason. If new deleterious mutation appears the inbreeding leads in two generations to aa homozygots that die or fail to procreate and the "bad" mutations are selected out fairly fast. Inbreeding is normal state for some species. Today inbreeding-resistant species are descendants of individuals who have survived many generations of inbreeding.
The following is multiple choice question (with options) to answer.
Not all structural rearrangements of chromosomes produce nonviable, impaired, or infertile individuals. in rare instances, such a change can result in the evolution of what? | [
"new order",
"new species",
"new mutation",
"new family"
] | B | The Chromosome 18 Inversion Not all structural rearrangements of chromosomes produce nonviable, impaired, or infertile individuals. In rare instances, such a change can result in the evolution of a new species. In fact, a pericentric inversion in chromosome 18 appears to have contributed to the evolution of humans. This inversion is not present in our closest genetic relatives, the chimpanzees. Humans and chimpanzees differ cytogenetically by pericentric inversions on several chromosomes and by the fusion of two separate chromosomes in chimpanzees that correspond to chromosome two in humans. The pericentric chromosome 18 inversion is believed to have occurred in early humans following their divergence from a common ancestor with chimpanzees approximately five million years ago. Researchers characterizing this inversion have suggested that approximately 19,000 nucleotide bases were duplicated on 18p, and the duplicated region inverted and reinserted on chromosome 18 of an ancestral human. A comparison of human and chimpanzee genes in the region of this inversion indicates that two genes—ROCK1 and USP14—that are adjacent on chimpanzee chromosome 17 (which corresponds to human chromosome 18) are more distantly positioned on human chromosome 18. This suggests that one of the inversion breakpoints occurred between these two genes. Interestingly, humans and chimpanzees express USP14 at distinct levels in specific cell types, including cortical cells and fibroblasts. Perhaps the chromosome 18 inversion in an ancestral human repositioned specific genes and reset their expression levels in a useful way. Because both ROCK1 and USP14 encode cellular enzymes, a change in their expression could alter cellular function. It is not known how this inversion contributed to hominid evolution, [1] but it appears to be a significant factor in the divergence of humans from other primates. Translocations A translocation occurs when a segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome. Translocations can be benign or have devastating effects depending on how the positions of genes are altered with respect to regulatory sequences. Notably, specific translocations have been associated with several cancers and with schizophrenia. Reciprocal translocations result from the exchange of chromosome segments between two nonhomologous chromosomes such that there is no gain or loss of genetic information (Figure 13.13). |
SciQ | SciQ-3991 | biochemistry, metabolism, bioenergetics
Title: What is the energy source for adipocytes? Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes? Adipocytes use glucose as an energy source. They express the insulin-responsive glucose transporter GLUT4 just like muscle cells so that when blood glucose levels rise they are primed to take the glucose up for fatty acid biosynthesis, but they also use glucose as a fuel molecule.
The following is multiple choice question (with options) to answer.
Which molecules in the body holds energy? | [
"mitochondria molecules",
"glucose molecules",
"water molecules",
"lipid molecules"
] | B | How does the food you eat provide energy? When you need a quick boost of energy, you might reach for an apple or a candy bar. But cells do not "eat" apples or candy bars; these foods need to be broken down so that cells can use them. Through the process of cellular respiration , the energy in food is changed into energy that can be used by the body's cells. Initially, the sugars in the food you eat are digested into the simple sugar glucose , a monosaccharide . Recall that glucose is the sugar produced by the plant during photosynthesis. The glucose, or the polysaccharide made from many glucose molecules, such as starch , is then passed to the organism that eats the plant. This organism could be you, or it could be the organism that you eat. Either way, it is the glucose molecules that holds the energy. |
SciQ | SciQ-3992 | java, performance, comparative-review, combinatorics
//--------choosing the point (position) where to put the new item----
for (int j=0; j<remainingBreadth.length; j++){
if ((remainingBreadth[j] != 0) && (minRemB >= remainingBreadth[j]) && (remainingBreadth[j] >= item.getBreadth())){
i=j; //choosing the item to which we should put the new packed item next to
minRemB=remainingBreadth[j]; //minimum length left
}
/*else {
return false; //------return false if all the positions cannot fit the new item
}*/
}
remainingBreadth[p]=remainingBreadth[i]-item.getBreadth(); //update the remaining breadth of the new item added
remainingHeight[p]-=item.getHeight();//update the remaining height of the new item added
remainingLength[p]-=item.getLength(); //update the remaining length of the new item added
remainingBreadth[i]=0; //insert 0 to the remainingBreadth of the item next to which we put the new item (so that we don't consider its remaining breadth anymore)
y+=item.getBreadth(); //increment y by the breadth of the new packed item in the extreme point of breadth
//x=length-remainingLength[p]; //update x to the position of the item next to which we put the new item
return true;
}
//-----------adding the new item to the extreme point in height
private boolean putH(ItemsUnit item, int p) {
double minRemH=remainingHeight[0]; //the minimum remaining height of all already packed items
int i=0; //to store the index of the item next to which we should put the new item
The following is multiple choice question (with options) to answer.
What term is used for the difference in the placement of an object from one time to another? | [
"displacement",
"diffusion",
"replacement",
"variation"
] | A | Position is the location of the object (whether it's a person, a ball or a particle) at a given moment in time. Displacement is the difference in the object's position from one time to another. Distance is the total amount the object has traveled in a certain period of time. Displacement is a vector quantity (direction matters), where as distance is a scalor (only the amount matters). Distance and displacement are the same in the case where the object travels in a straight line and always moving in the same direction. |
SciQ | SciQ-3993 | under the authority of the Food Drug and Cosmetic Act or under the authority of the Public Health Service Act. This abstraction of the formulation of arguments is one of the central themes in formal logic. The general strategy for predicate logic derivations is to work through these three phases: (1) instantiate the premises, (2) work with what you have then, using the original 19 rules plus CP and IP, and (3) then generalize as needed to put the right quantifiers on the conclusion. Introduction to Predicate Logic. metic rules. The reader could try exploring why these propositions have the claimed translation in English and try out the same for three or more. Let OxyOxyOxy mean that xxx owns yyy, Then ∃x∃y(Dx∧Oyx)\exists x \exists y ( Dx \wedge Oyx) ∃x∃y(Dx∧Oyx) means somebody owns a dog. We do not yet show how predicate logic succeeds in demonstrating the validity of the argument; this will be made clearer to the reader in subsequent sections. It was a mechanical method, that would yield, in a finite number of steps, answers to questions of satisfiability and validity. An answer to the question, "how to represent knowledge", requires an analysis to distinguish between knowledge “how” and knowledge “that”. Here is the rule being used 3 times in a row. ∃x∀yLyx\exists x \forall y Lyx∃x∀yLyx means that there is somebody who everyone likes. In choosing a set of rules for predicate logic, one goal is to follow the general pattern established in sentential logic. Predicate Logic is an extension of Propositional Logic not a replacement. Therefore, Aristotle is mortal. An argument is a … We'll illustrate this with an example. Finally, we are ready to define a proposition as follows: Just to be more rigorous, we formally define. However, if we say ∃x(Gx→Gl)\exists x (G x \to Gl ) ∃x(Gx→Gl), we have changed the scope of the quanitifier to the entire expression. satisfies (a), (b),and (c). And what we need to be careful of is whether the individual, or constant that represents it, is already in the tree or in the context. Predicate logic is superior to propositional logic in the sense that it is able to capture the
The following is multiple choice question (with options) to answer.
What kind of reasoning involves formulating generalizations inferred from careful observation and the analysis of a large amount of data? | [
"reflexive",
"deductive",
"skepticism",
"inductive"
] | B | These data can be qualitative (descriptive) or quantitative (consisting of numbers), and the raw data can be supplemented with drawings, pictures, photos, or videos. From many observations, the scientist can infer conclusions (inductions) based on evidence. Inductive reasoning involves formulating generalizations inferred from careful observation and the analysis of a large amount of data. Brain studies often work this way. Many brains are observed while people are doing a task. The part of the brain that lights up, indicating activity, is then demonstrated to be the part controlling the response to that task. Deductive reasoning or deduction is the type of logic used in hypothesis-based science. In deductive reasoning, the pattern of thinking moves in the opposite direction as compared to inductive reasoning. Deductive reasoning is a form of logical thinking that uses a general principle or law to forecast specific results. From those general principles, a scientist can extrapolate and predict the specific results that would be valid as long as the general principles are valid. For example, a prediction would be that if the climate is becoming warmer in a region, the distribution of plants and animals should change. Comparisons have been made between distributions in the past and the present, and the many changes that have been found are consistent with a warming climate. Finding the change in distribution is evidence that the climate change conclusion is a valid one. Both types of logical thinking are related to the two main pathways of scientific study: descriptive science and hypothesisbased science. Descriptive (or discovery) science aims to observe, explore, and discover, while hypothesis-based science begins with a specific question or problem and a potential answer or solution that can be tested. The boundary between these two forms of study is often blurred, because most scientific endeavors combine both approaches. Observations lead to questions, questions lead to forming a hypothesis as a possible answer to those questions, and then the hypothesis is tested. Thus, descriptive science and hypothesis-based science are in continuous dialogue. |
SciQ | SciQ-3994 | volcanology, paleontology, volcanic-hazard, archaeology, pyroclastic-flows
Title: Are Pompeii and Herculaneum unique? Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human – have been entombed in the volcanic ash, with the possibility of revealing their forms by producing casts from the voids? Such sites, if they exist, could reveal exciting new knowledge about ancient peoples and animals. Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.
The following is multiple choice question (with options) to answer.
What kind of eruption do scientists think is caused by a very large magma chamber erupting entirely in one catastrophic explosion? | [
"supermagma eruption",
"supervolcano eruption",
"mangxamba eruption",
"brucei eruption"
] | B | The exact cause of supervolcano eruptions is still debated. However, scientists think that a very large magma chamber erupts entirely in one catastrophic explosion. This creates a caldera into which the surface collapses ( Figure below ). The composition of the eruption is felsic or highly felsic. |
SciQ | SciQ-3995 | 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.
The inside surface of the jejunum is covered with tiny projections called what? | [
"villi",
"alveoli",
"flagella",
"mucosa"
] | A | The jejunum is the second part of the small intestine. This is where most nutrients are absorbed into the blood. The inside surface of the jejunum is covered with tiny projections called villi (villus, singular). The villi make the inner surface of the small intestine 1000 times greater than it would be without them. You can read in Figure below how villi are involved in absorption. |
SciQ | SciQ-3996 | genetics, vision
Females who are heterozygous for red and green pigment genes that encode three
spectrally distinct photopigments have the potential for enhanced color vision, as they are effectively tetrachromats (Deeb, 2005, Neitz et al., 1991). However, sensitive color-contrast testing on 43 tetrachromats has revealed that most of these females have no deviating color-discrimination whatsoever. 8 subjects showed relatively small effects, while only one showed a clear increased sensitivity in a narrow range of frequencies. It is believed that the human visual system is not plastic enough to cope with the extra spectral input. In fact, in the group there was an overall increase in error rates on some color tests (pseudoisochromatic plates, and Nagel anomaloscope color matching) (Jordan & Mollon, 1993).
In New World Monkeys, however, the situation is different. Squirrel monkeys are basically a dichromatic species, but two-thirds of the females are heterozygous, and gain trichromatic vision by expressing two of three possible alleles coding for pigments in the middle- to long-wave range of the spectrum. X-chromosome inactivation serves to segregate the alternative allelic products in different subsets of cones. The visual system of the heterozygous female is apparently plastic enough to take advantage of the presence of three classes of cone, because heterozygous monkeys have enhanced color selectivity in the red-green range that are impossible for all males and for homozygous females. This advantage perhaps enables the heterozygote to judge better the ripeness of fruit, or to find fruit or conspecifics (Jordan & Mollon, 1993).
Note that the emergence of trichromacy in humans and some other primates was the result of the red/green gene duplication. Trichromacy in primates was evolutionary selected for likely because of the enhanced capability to discern (ripe) fruits (Lucas et al., 2003). It has nothing to do with sex-differences, because not many human females benefit from tetrachromacy in terms of enhanced color vision.
References
- Deeb, Clin Genet (2005); 67: 369–377
- Jordan & Mollon, Vis Res (1993); 33(11): 1495-1508
The following is multiple choice question (with options) to answer.
What is the most effective color in interrupting the nighttime portion of the photoperiod? | [
"blue light",
"red light",
"white light",
"yellow"
] | B | |
SciQ | SciQ-3997 | ichthyology, homeostasis, osmoregulation
Pillans, R.D. and C.E. Franklin, 2004. Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient. Comparative Biochemistry and Physiology, Part A 138: 363-371.
The following is multiple choice question (with options) to answer.
What glands produce the salty fluid that helps cool the body of many mammals? | [
"water gland",
"sweat gland",
"endocrine gland",
"thyroid gland"
] | B | The skin of many mammals is covered with sweat glands. The glands produce sweat, the salty fluid that helps cool the body. |
SciQ | SciQ-3998 | newtonian-mechanics, newtonian-gravity, orbital-motion
Title: Is the shape of an orbit unique for a given energy? Consider a body at a given distance from a star. If we project it perpendicular to the radius vector at the correct velocity, the body can undergo circular motion about the star. However, if we project it at an angle to the radius vector with the same velocity, I would expect it to undergo an elliptical orbit; however, will this orbit devolve into the circular orbit, i.e. for a given energy, is the orbit of the body unique? No.
For any given energy, there is a continuum of keplerian orbits that range from a fully circular orbit to more highly elliptical motions, all the way up to the limiting case of an almost-linear motion (extremely elliptical orbit) that whips around the focus infinitely sharply. These correspond to storing more or less energy in radial vs angular motion, i.e. to the angular momentum of the orbit.
There is also, of course, a three-dimensional degeneracy in the orientation of the orbit (usually given by three orbital elements such as the inclination, ascending node, and argument of periapsis) but dynamically speaking that is less interesting than the 'shape' degeneracy that comes from the variability in angular momentum.
And, for clarity, in a two-body problem, keplerian elliptical orbits are completely stable, and none of them "devolves" into any of the others. If there is a third body present then this changes (often quite dramatically) but then the space of possibilities becomes impossibly large to describe here.
The following is multiple choice question (with options) to answer.
What shape is the orbit of a planet? | [
"cleaved",
"spiral",
"elliptical",
"vertical"
] | C | The orbits of the planets are elliptical. |
SciQ | SciQ-3999 | evolution, ecology, natural-selection, adaptation
Title: What are Some Classical Examples of Local Adaptation? Question
Can you please give a list of classical (textbook) examples of local adaptations?
How to answer
Examples don't necessarily need to include what evidence supports this specific example of local adaptation. A simple description of the local adaptation (e.g. coat colour changes from black on dark soil to white on light soil) and an brief explanation of the reason (e.g. because being nicely camouflaged prevents from predation from hawks) is enough.
I think a list of 10 or more such examples would be great.
Definition of local adaptation
Note that I define here local adaptation as differentially adapted subpopulation of a single species (with existing gene flow between subpopulations especially for sexually reproducing species).
Justification for the question
I found surprisingly complicated to find such list online. I think it could be a valuable post for many.
Examples
Examples of local adaptation (that you are free to add in your answer with a description) include beach mice camouflage, altitude adaptation in tibetans and peppered-moth camouflage. Adaptation is a change in a trait as a response to selection. As you ask for local adaptation I assume you want examples where sub-populations have either come under different selection and adapted differently, or cases where sub-populations have come under similar selection but not all have had the necessary genetic variation to evolve, i.e. selection has caused differentiation between sub-populations. Local adaptation can lead to varying degrees of divergence, so some for some examples it may be worth exploring speciation events. Here's some examples:
Galapagos Tortoises
There are two general shapes to the shell of tortoises on the Galapagos Islands. On islands with little low-lying vegetation the tortoises seem to have evolved long necks & limbs and different shell shapes which allow them to reach up more easily.
"The shell distortion and elongation of the limbs and neck in saddlebacks is probably an evolutionary compromise between the need for a small body size in dry conditions and a high vertical reach for dominance displays."
The following is multiple choice question (with options) to answer.
What term is defined as the area where a species lives and to which it has become adapted? | [
"habitat",
"range",
"nature",
"farmland"
] | A | The single biggest cause of the sixth mass extinction is habitat loss. A habitat is the area where a species lives and to which it has become adapted. When a habitat is disturbed or destroyed, it threatens all the species that live there with extinction. |
SciQ | SciQ-4000 | zoology, experimental
Title: Fish "coming back to life" after being frozen I've encountered a clip on Youtube showing a goldfish thrown in liquid nitrogen and immediately after to normal water and swimming normally. In the explanation to the clip it says:
For everyone that is worried about the goldfish, it survived and was perfectly fine until we fed him and a few of his friends to our turtles. (Which is what they were bought for in the first place!)
I am wondering now as to several issues.
If the goldfish wasn't fed to the turtles and was allowed to live out its life, would it suffer any long term damages from the act?
Is time an issue here, if the fish was kept frozen for a longer time, would it suffer more damage and would it be able to be revived?
Is the size and nature of the fish's body a factor? Would a larger animal or an animal with better resistance to frost that would take more time to completely freeze have damage due to gradual freezing of body and systems?
Does the fact that fish have cold blood affect the result of the experiment? I have no idea what's the real reason for the survival of the poor fish, but I would guess this is all in the timing. I know for certain ;-) that one can submerge a hand in liquid nitrogen for a short time or in general one can pour liquid nitrogen on the skin with no harm done whatsoever.
The reason is that the difference in temperature that interface (-180 deg C or so for liquid nitrogen and 20-30 for the skin surface) is so large that nitrogen vaporizes instantly and does not penetrate/affect the tissue. The demonstrator could have pulled the fish with bare hands.
I think that for the goldfish the time was too short and while it was cooled/shocked a bit, it might have been too short to do any serious damage. But -
As a scientist, I can't help but notice that we don't really know the condition of the fish before or after the liquid nitrogen 'treatment'. We only see it flapping for a few seconds when back in water. I wonder what happened to the eyes and the mouth, both quite sensitive tissues for such a shock. Also, the water the fish was in was a factor probably, providing additional buffer between the fish and the liquid nitrogen.
Last but not least, the ethical committee quite certainly did not approve that demonstration.
The following is multiple choice question (with options) to answer.
What do fish have that allow them to “breathe” oxygen in water? | [
"pores",
"gills",
"layers",
"lungs"
] | B | Fish have gills that allow them to “breathe” oxygen in water. Water enters the mouth, passes over the gills, and exits the body through a special opening. Gills absorb oxygen from the water as it passes over them. |
SciQ | SciQ-4001 | thermodynamics, experimental-physics, heat-conduction
I suspect that, for solids, the pressure that the system exerts against the atmosphere is just the pressure of not collapsing in on itself, os it is involved with the structure of the material. That rate of change then has to do with how difficult it is to expand the material, which has to be related with how strongly are the inter-particle interactions that maintain the material structure of the system since any expansion would be done against the binding energy of the internal structure. It's just a more complicated way to express the $\left(\frac{\partial U}{\partial V}\right)_{T}$ term of the main body of the answer. I think I read once that this measure is called free volume, let's call it $\gamma$.
The term $\left( \frac{\partial p}{\partial T} \right)_V$ is a measure of how much the pressure that the material exerts change as a function of its temperature. It's the pressure equivalent of the thermal expansion coefficient, I don't know its name but let's call it $\beta$ just to keep the greek-letter motif. With this we have that:
$$
\dot H =
\gamma \beta \frac{\mathrm{dT}}{\mathrm{dt}}
+C_p\dot T
$$
From here it is easy to see that if we have a heat source with power $\dot H$ then:
$$
\dot T=\frac{\dot H}{\gamma \beta + m c_p}
$$
which has the same structure as the other one. This is expected since the terms we are trying to get rid of are related to the strength of the chemical interactions in the material structure of the system, which is a big deal for solids.
New Suggestion by Chemomechanic
So in a new comment Chemomechanic said that:
The following is multiple choice question (with options) to answer.
The process in which materials move depending on their heat relative to nearby materials is known as what? | [
"convection",
"ventilation",
"induction",
"radiation"
] | A | In convection, materials move depending on their heat relative to nearby materials. |
SciQ | SciQ-4002 | # Name the generalization of regular tetrahedron in higher dimension
By a regular tetrahedron, I’m referring to the tetrahedron formed by connecting the vertices of the $3$-simplex with the “far corner” $(1, 1, 1)$. That is, the four vertices of this regular tetrahedron are $(1, 0, 0) ,\, (0, 1, 0) ,\, (0, 0, 1)$, and $(1, 1, 1)$, shown as blue edges one on the right.
My question is this:
What do you call the counterpart (generalization) of such tetrahedron in higher dimensions?
That is, connect the vertices of the $n$-simplex with the "far corner" $(1, 1, 1,\ldots 1)$ so that one gets a shape which vertices are the unit vectors $e_i$ and $\sum e_i$, and the sides have the same length $\sqrt{n-1}$.
If there's not a name for such construction, how about alternatively connect the origin $(0, 0, 0)$ with $(0, 1, 1) ,\, (1, 0, 1) ,\, (1, 1, 0)$?
This alternative tetrahedron is shown below with orange edges. One can compare it with the previous one involving the simplex with blue edges.
The higher dimension counterpart of the orange tetrahedron has vertices being the complement (binary flip) of that from the blue one, e.g. $(0,1,0,\ldots, 0) \to (1,0,1,\ldots, 1)$. It is congruent to the previous one, also with side length $\sqrt{n-1}$.
The following is multiple choice question (with options) to answer.
What shape is each face of a tetrahedron? | [
"trapezoid",
"oval",
"equilateral triangle",
"asymmetric triangle"
] | C | In order to maximize their distance from one another, the four groups of bonding electrons do not lie in the same plane. Instead, each of the hydrogen atoms lies at the corners of a geometrical shape called a tetrahedron. The carbon atom is at the center of the tetrahedron. Each face of a tetrahedron is an equilateral triangle. |
SciQ | SciQ-4003 | circulatory-system, lymphatic-system, veins
Title: How does most of lymph get back into the blood stream? (I don't mean the lymphatic system) I once read that it was because of osmotic pressure that it returns to the blood stream, by entering the venules. But why? If lymph originated as plasma how come that the solute concentration is higher in the venule? Doesn't plasma contain solutes such as salts, nutrients, oxygen, etc. ? Technically 'lymph' is used to refer to the fluid found within the lymphatic system. If it's not in the lymphatic system, it is not lymph fluid. Thus, your question is really asking about interstitial fluid or the plasma that was filtered out of blood capillaries.
The answer to your question is based on the Starling equation. Normally fluid leaves a capillary due to a net pressure that favors the interstitium. This net pressure is based on the hydrostatic pressure within the capillary being greater than the interstitial pressure of the surrounding tissues, and the oncotic pressure of the capillary (that draws fluid in) being weaker than the hydrostatic pressure of the capillary (that pushes fluid out). At the venule end of this system, the capillary oncotic pressure is stronger than the capillary hydrostatic pressure, drawing fluid back into the circulatory system.
Remember that albumin is the most important component which establishes the oncotic pressure within a vessel, and that this protein is normally NOT released out of a vessel during filtration. Thus, it passes from the capillary into its corresponding venule directly.
The following is multiple choice question (with options) to answer.
Glands release what substance into the blood? | [
"toxins",
"hormones",
"enzymes",
"acids"
] | B | human body system of glands that release hormones into the blood. |
SciQ | SciQ-4004 | atmospheric-science, density, air
Title: Why does the composition of the air does not change with altitude? Air contains about 78% nitrogen and 21% oxygen independent of altitude (up to 100 km). Why is this? Shouldn't the concentration of nitrogen increase with higher altitudes since nitrogen has a lower density than oxygen?
Shouldn't the concentration of nitrogen increase with higher altitudes since nitrogen has a lower density than oxygen?
No, it shouldn't, at least not up to 100 km or so. Look at your graph, which shows that even argon is well-mixed throughout the lower atmosphere (the troposphere, stratosphere, and mesosphere). Argon atoms are considerably more massive than are carbon dioxide molecules, which in turn are considerably more massive than oxygen and nitrogen molecules, and yet all of these (along with all of the long-lived gases in the atmosphere) are well-mixed throughout the lower atmosphere.
The reason is that the lower atmosphere is dense enough to support turbulence while the upper atmosphere is not. The turbopause marks the somewhat fuzzy boundary below which turbulent mixing dominates over diffusion and above which it's diffusion that dominates.
The following is multiple choice question (with options) to answer.
What's the process responsible for the presence of oxygen in our atmosphere? | [
"respiration",
"ozone",
"glycolysis",
"photosynthesis"
] | D | |
SciQ | SciQ-4005 | biochemistry, endocrinology, electrophysiology
Title: Why does depolarisation by high intracellular K+ trigger calcium channels opening? I have learnt that in pancreatic beta cells, glucose being metabolised in the cell causes a high ATP level, which triggers ATP-dependent potassium channels to close. This means that potassium can't leave the cell anymore, which depolarises the membrane and causes voltage-gated calcium channels to open and release calcium into the cell to trigger insulin release. I don't understand why this happens, because both potassium and calcium being positively charged. Wouldn't this depolarise the membrane even more? I thought this would be unfavourable. Ca2+ is very often the trigger to release neurotransmitter or, in this case, hormones. Ca2+ entry in the cell is important to activate the fusion of secretory vesicles with the membrane in pancreatic beta cells as shown in Fig. 1 (Thurmond, 2000). The function of Ca2+ entry is not so much related to its depolarizing actions.
The following is multiple choice question (with options) to answer.
A rise in blood glucose levels triggers the pancreatic release of what hormone? | [
"testosterone",
"insulin",
"hemoglobin",
"estrogen"
] | B | Humoral Stimuli The term “humoral” is derived from the term “humor,” which refers to bodily fluids such as blood. A humoral stimulus refers to the control of hormone release in response to changes in extracellular fluids such as blood or the ion concentration in the blood. For example, a rise in blood glucose levels triggers the pancreatic release of insulin. Insulin causes blood glucose levels to drop, which signals the pancreas to stop producing insulin in a negative feedback loop. |
SciQ | SciQ-4006 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
What do most ecosystems get energy from? | [
"moisture",
"magma",
"sunlight",
"evaporation"
] | C | When it comes to energy, ecosystems are not closed. They need constant inputs of energy. Most ecosystems get energy from sunlight. A small minority get energy from chemical compounds. Unlike energy, matter is not constantly added to ecosystems. Instead, it is recycled. Water and elements such as carbon and nitrogen are used over and over again. |
SciQ | SciQ-4007 | virology, nomenclature
Title: Why is it called "Ebola virus disease", not just "Ebola" or "Ebola disease"? Why do scientists (pretty consistently) call it Ebola virus disease, rather than just Ebola, or Ebola disease?
Many other diseases are caused by viruses, but they don't seem to have this detail of terminology. Nor do you hear the analogous terminology for bacteria.
For example:
The following is multiple choice question (with options) to answer.
What is the study of viruses called? | [
"virology",
"biotechnology",
"microbiology",
"immunology"
] | A | The life sciences are so complex that most scientists focus on just one or two subspecialties. If you want to study insects, what would you be called? An entomologist. If you want to study the tiny things that give us the flu, then you need to enter the field of virology , the study of viruses. If you want to study the nervous system, which life science field is right for you ( Table below , Table below , and Table below )?. |
SciQ | SciQ-4008 | evolution, species
Title: Parents that eat their own children I am told that there are some species, like fish or rabbits, that if let, will eat their own children. If this is true, how does a species like this exist? Shouldn't the fact that they kill their own lineage make them nonviable? Yes, it is true.
Prairie dogs
Prairie dogs for example are known for frequent infanticides.
Many other species kill their babies too
But of course, such behaviour also exists in other lineages such as grey langurs, gerbilles, lions, giant water bugs and Bottlenose dolphins (just to cite a few examples).
How does that evolve
It will be impossible to provide a complete universal explanation to this behaviour because the evolutionary processes causing this behaviour varies from lineage to lineage. For examples, in lions, only males kill young of the females that are still nursing and they do so when taking over a new harem only. In prairie dogs, mothers cause infanticide preferentially on others' babies but also on their own babies.
Going into the details of how such behaviour evolves in every specific lineage would probably require writing an intro on kin selection and other fields of evolutionary biology which is way too much for a single post. You may want to have a look at the wikipedia article infanticide for a start.
Shouldn't the fact that they kill their own lineage make them nonviable?
Of course, they don't kill all the babies. Only a fraction of them!
The following is multiple choice question (with options) to answer.
What do you call an animal that feeds on other animals? | [
"polyvore",
"carnivore",
"omnivore",
"herbivore"
] | B | Birds live in a variety of different habitats. Birds that live in different habitats will encounter different foods and different predators. Birds can be carnivores (feeding on other animals), herbivores (feeding on plants), or generalists (feeding on a variety of foods). The lifestyle of the bird can affect what it looks like. For example, can you think of some examples of beaks that are adapted to the type of food a bird eats? Carnivorous birds include hawks, falcons, eagles, osprey, vultures and owls. Herbivorous birds include the goose, cockatoo and parrot. The American Crow is an example of a generalist. In addition, a specialist is a bird (or other animal) that is specially adapted to eat a certain food. An example of a specialist is a hummingbird, whose long, thin beak is excellent for reaching into flowers for nectar, but not very good for eating other foods. |
SciQ | SciQ-4009 | vacuum, space
Title: What is in space? I was recently on a chat server having a random discussion about science stuff and someone I was talking to then made the comment that "space is not a complete vacuum and it's full of plasma / matter".
That got me thinking ... ok so I don't expect that the bulk of space is totally empty but if I took a "cube volume of the space outside the ISS" (or further out for scientific accuracy) ... do we know what would be observed inside that cube in terms of "real particles" from the standard model?
I'm thinking that there would be some amount of photons (light) and possibly some other stuff, by the other guys claim of "plasma being everywhere" raised some weirdness in my head I couldn't resolve.
He followed that up with "we live in an electric universe".
Does anyone have a professional / academic viewpoint on this (i'm no physics grad though so go easy on me)?
EDIT:
I've had time to go deeper in to this concept with the person I was talking to earlier and he cited NASA as a source and linked me to this ...
https://science.nasa.gov/science-news/science-at-nasa/1999/ast07sep99_1
This article clearly states ...
"99.9 percent of the Universe is made up of plasma," says Dr. Dennis Gallagher, a plasma physicist at NASA's Marshall Space Flight Center. "Very little material in space is made of rock like the Earth."
... surely this is a contextual statement but what is the context and does this literally mean as is worded or is there something else here? 1) To begin with, space or the interstellar medium if that is what you are refering to, accounts for all the matter that is not in stars, neither in planets or asteroids, and there is actually a lot of matter in there.
The following is multiple choice question (with options) to answer.
Most scientists think that ordinary matter is less than half of the total matter in the universe; the remaining part includes what mysterious entity? | [
"dark matter",
"cold matter",
"mystery matter",
"magic matter"
] | A | Most scientists who study dark matter think it is a combination. Ordinary matter is part of it. That is mixed with some kind of matter that we haven’t discovered yet. Most scientists think that ordinary matter is less than half of the total matter in the universe. |
SciQ | SciQ-4010 | optics, laser, gas, absorption
Title: Can gases be heated by absorbing laser light? I have a narrow gas jet, with a laser pointed at it. I want to figure out whether the gas will absorb any thermal energy from the laser photons, if they are at a wavelength that the gas can absorb.
For example, I have a 532nm laser, and a Ne gas jet. As far as I can tell from the (oddly contradictory?) sources I have seen, Ne has an absorption peak at 532nm. When it absorbs light from the laser, will it heat the gas up? Or will it simply excite an electron that later de-excites and produces another photon?
And if it does heat it up, is there any way I can get a figure on the added energy given the cross sections and laser power?
The only literature I can find on this topic just talks about gas-assisted heating of solid surfaces. Am I misunderstanding something here? The answer to the (general) title question is definitely 'yes,' and the answer to the more specific text is probably yes as well.
In the limit in which the only emission is stimulated emission by the 532 laser, then the effect of absorption is precisely counteracted by that of emission. This will only happen for light that has a strong intensity relative to the characteristic saturation intensity of the atomic transition. For light that is weaker than this, there will be both spontaneous emission and stimulated emission. Because the spontaneous emission is isotropic, it leads to random momentum kicks in every direction, and thus heating. If there are any alternate decay channels besides the driven transition, this can also lead to similar heating from random emission.
Just for fun, I should also point out that it's even possible to have a gas be cooled by laser light, by arranging things so that emission is preferentially in the opposite direction of the atom's motion. This relies on a careful engineering of the light detuning and balancing of non-cooling forces, and it's easy to get a little away from these conditions and cause runaway heating instead.
A good reference for light-atom interactions is Laser Cooling and Trapping by Metcalf and van der Straten. They mostly develop the theory for the simple case of an alkali atom with a hydrogen-like structure; I'm not sure exactly how this changes for an atom like neon but I suspect it allows more inelastic decay channels.
The following is multiple choice question (with options) to answer.
What is the term for gases that absorb heat in the atmosphere? | [
"ionic gases",
"thermal gases",
"greenhouse gases",
"sulfuric gases"
] | C | Gases that absorb heat in the atmosphere are called greenhouse gases . They include carbon dioxide and water vapor. Human actions have increased the levels of greenhouse gases in the atmosphere. This is shown in Figure below . The added gases have caused a greater greenhouse effect. How do you think this affects Earth’s temperature?. |
SciQ | SciQ-4011 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
What is the type of cell division that produces gametes called? | [
"fertilization",
"mitosis",
"meiosis",
"electrolysis"
] | C | During sexual reproduction, two haploid gametes join in the process of fertilization to produce a diploid zygote. Meiosis is the type of cell division that produces gametes. It involves two cell divisions and produces four haploid cells. |
SciQ | SciQ-4012 | nomenclature, ionic-compounds, history-of-chemistry
Title: How did Halogens become known as Halogens? They are not the only elements that form salts! Having never given it a though before, I recently discovered (in a different context) that the prefix halo- actually means 'salt' or 'sea' and the suffix -gen means 'to form' or 'to generate'. So the Halogens are the elements that 'form salts'. But there are salts that do not have halogens in them, like $\ce{Na2S}$ or $\ce{(NH4)2SO4}$. Was it known at the time that other salts existed, and what other names for this group might have been considered?
On a side note, why aren't Group I metals called halogens? Doesn't it take two to tango (I mean, to form salts?) This seems like a bit of a rhetorical question, so this isn't a terribly formal or authoritative answer, but anyhow - a lot of chemical nomenclature is like lava flow. It solidified and people just worked around it.
The halogens are so named because they have a rich chemistry of ionic compounds (fluorine through iodine, anyhow). However, both the halogens and the group I metals can form a wide range of things that aren't salts. The noble gases can form compounds with elements of low birth. The rare earth elements aren't particularly rare. Oxygen ('acid-former') is not a necessary component of acids. Technetium ('artificial' + ium) is produced in nature in significant quantities.
In addition, a lot of chemistry defies our human efforts to succintly categorise things, so at some point chemists have tried their best to find pragmatic general descriptors that unite groups of elements or molecules on the basis of the properties or constitution. The divide between organic and inorganic chemistry and the resulting exceptions and edge cases in classification (such as mellitic anhydride) is a good example of this. The map is not the territory.
The following is multiple choice question (with options) to answer.
What causes halide minerals to form? | [
"salt water ionization",
"fresh water ionization",
"salt water evaporation",
"salt water accumulation"
] | C | Halide minerals are salts. They form when salt water evaporates. This mineral class includes more than just table salt. Halide minerals may contain the elements fluorine, chlorine, bromine, or iodine. Some will combine with metal elements. Common table salt is a halide mineral that contains the elements chlorine and sodium. Fluorite is a type of halide that contains fluorine and calcium. Fluorite can be found in many colors. If you shine an ultraviolet light on fluorite, it will glow!. |
SciQ | SciQ-4013 | neuroscience, neurotransmitter, synapses
Title: Do presynaptic neurons and postsynaptic neurons have different compositions of neurotransmitter receptors and transporters? For example if certain neurotransmitter is released, will there be neurons that won’t be even potentially affected, because it doesn’t have such type receptors? Typical bouton-spine synapses are formed as an interactive process between the pre- and post-synaptic cells (Scheiffele, 2003). There is communication between pre- and post-synaptic cell through guidance cues, growth factors, and structural proteins, as well as neurotransmitter release itself. Therefore, as part of the normal developmental process, postsynaptic cells will usually have receptors for the major neurotransmitter released by the presynaptic cells: they find each other rather than connecting at random.
Synapses that become inactive or have lower activity than their neighbors can also degrade and disappear entirely (Purves and Lichtman, 1980) by a competitive process (Balice-Gordon and Lichtman, 1994). Because of this process, I would expect that even if some developmental fluke led to a formation of a synapse between mismatched pre/post neurotransmitter release/receptors, the result would be that the synapse would get no stimulation and would be pruned according to the normal process.
However, some neurotransmitters can be released more broadly into the extracellular space rather than at highly specialized synapses (including serotonin, dopamine, and acetylcholine - note: these neurotransmitters can also be released at synapses) (De-Miguel and Trueta, 2005; Trueta and De-Miguel, 2012) and call also 'leak' from synapses into the extrasynaptic space: in these cases, the neurotransmitter is not likely to have an effect (or the same effect) on all nearby dendrites, only those that express fairly high-affinity receptors that can detect the neurotransmitter at an extrasynaptic concentration.
References:
The following is multiple choice question (with options) to answer.
Upon reaching the postsynaptic membrane, what type of chemical messenger binds to and activates a specific receptor? | [
"hormone",
"neuropeptide",
"pheromone",
"neurotransmitter"
] | D | |
SciQ | SciQ-4014 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
What do heterotrophic animals usually consume? | [
"soil",
"minerals",
"plants",
"other organisms"
] | D | Animals are multicellular eukaryotes in the Animal Kingdom. They are heterotrophic, meaning that they consume other organisms. Animals have specialized cells and often higher levels of organization. This allows them to do things that other eukaryotes cannot, such as move and digest food internally. Animals generally have a simple life cycle. |
SciQ | SciQ-4015 | earth-history
Common elements in space, such as CO2, H20, CH4 and NH3 are gaseous at Earth's distance from the sun and as a result, are unlikely to stick to anything in the Earth's formation region. This is true for all 4 inner planets and likely all rocky worlds. Rocky planets likely can only form close to their star, just as gas giants, ice giants or other icy abundant bodies like comets and low-density moons, can only form further out.
Gases like the 4 above can begin to be retained around a planet after it reaches a sufficiently large mass with low enough surface temperature to retain those gases by gravity.
The boundaries where CO2, H20, CH4, NH3 and other gases can be found in the protoplanetary disk is called the frost line. Different gases have different frost lines depending on their freezing point.
It's thought that much of Earth's water, CO2, CH4 and NH3 came to the Earth by comet after the planet formed. There's still some uncertainty on the percentages, as some of those elements could have been trapped during formation.
Just to add, hydrogen and helium are obviously abundant, but will only begin to accrue around a planet of a certain mass. In our solar-system, only Jupiter and Saturn are massive enough to accrue hydrogen and helium. That's why Uranus and Neptune are relatively low on hydrogen and helium compared to the universal abundance.
Argon is in Earth's atmosphere because it forms from gradual radioactive decay of Potassium-40. Earth's Helium is also present as a result of radioactive decay.
The following is multiple choice question (with options) to answer.
Molecules of gas are rare in what outermost region of the planet's atmosphere? | [
"ozone layer",
"thermosphere",
"ionosphere",
"exosphere"
] | D | Gas molecules are exceedingly rare in the exosphere. |
SciQ | SciQ-4016 | paleoclimatology
Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes. This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.
The following is multiple choice question (with options) to answer.
Why is there very little evaporation in the boreal forests? | [
"temperature is too cold",
"too hot",
"too humid",
"high elevation"
] | A | Arctic Tundra The Arctic tundra lies north of the subarctic boreal forests and is located throughout the Arctic regions of the Northern Hemisphere (Figure 20.18). Tundra also exists at elevations above the tree line on mountains. The average winter temperature is –34°C (–29.2°F) and the average summer temperature is 3°C–12°C (37°F –52°F). Plants in the Arctic tundra have a short growing season of approximately 50–60 days. However, during this time, there are almost 24 hours of daylight and plant growth is rapid. The annual precipitation of the Arctic tundra is low (15–25 cm or 6–10 in) with little annual variation in precipitation. And, as in the boreal forests, there is little evaporation because of the cold temperatures. Plants in the Arctic tundra are generally low to the ground and include low shrubs, grasses, lichens, and small flowering plants (Figure 20.26). There is little species diversity, low net primary productivity, and low aboveground biomass. The soils of the Arctic tundra may remain in a perennially frozen state referred to as permafrost. The permafrost makes it impossible for roots to penetrate far into the soil and slows the decay of organic matter, which inhibits the release of nutrients from organic matter. The melting of the permafrost in the brief summer provides water for a burst of productivity while temperatures and long days permit it. During the growing season, the ground of the Arctic tundra can be completely covered with plants or lichens. |
SciQ | SciQ-4017 | organic-chemistry, biochemistry, home-experiment, mixtures, colloids
Sugars. Milk is rich a variety of di- and oligo-saccharides such as the eponymous lactose, as well as many other more complex molecules:
[Free oligosaccharides are natural constituents of all placental mammals' milk. Human milk contains 7–12 g/L oligosaccharides, making the oligosaccharide fraction a major component of human milk. Compared with human milk, the concentration of oligosaccharides in the milk of the most relevant domestic mammals is smaller by a factor of 10 to 100.]
The following is multiple choice question (with options) to answer.
Maltose, lactose, and sucrose are common types of what, which are distinguished by their monosaccharide constituents? | [
"oxides",
"silicates",
"precipitates",
"disaccharides"
] | D | The disaccharides differ from one another in their monosaccharide constituents and in the specific type of glycosidic linkage connecting them. There are three common disaccharides: maltose, lactose, and sucrose. All three are white crystalline solids at room temperature and are soluble in water. We’ll consider each sugar in more detail. |
SciQ | SciQ-4018 | waves, interference, wavelength, superposition
The wavelength is the distance of a "cycle". Take the horizontal length between any two crests, or any two troughs, and what you get is called the wavelength. In physics, this is notated with the $\lambda$ symbol (the Greek letter Lambda). In the plot above, the wavelength has a value of $\pi$.
The amplitude is the height from the centre line to either the crest or the trough.
Destructive interference happens when the squared amplitude of the sum of the waves is lower than the sum of the squared amplitudes of the waves.
Therefore, the interference between two waves is the "most destructive" when the phase difference is an odd number of half-wavelengths, as shown in the plot above with the "$\pi/2$", "$3\pi/2$", "$5\pi/2$" points on the horizontal axis.
The following is multiple choice question (with options) to answer.
Amplitude describes what about the wave's crest and trough? | [
"How frequently the parts occur",
"The minimum parts",
"the maximum parts",
"The width of the parts"
] | C | Waves are identified by several characteristics. There is a center line where the medium would be if there were no wave, which is sometimes describes as the undisturbed position. The displacement of the medium above this undisturbed position is called a crest and the displacement below the undisturbed position is called a trough . The maximums of the crest and trough are equal and are called the amplitude . The distance between equivalent positions on succeeding waves is called the wavelength . The wavelength could be measured from a crest to the next crest or from a trough to the next trough, and is commonly represented with the Greek letter lambda, . |
SciQ | SciQ-4019 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
Overproduction of offspring, combined with limited resources, results in what? | [
"concentration",
"contention",
"continuation",
"competition"
] | D | |
SciQ | SciQ-4020 | orbit, earth, radiation
Now imagine what could happen if a person were to be exposed in a similar fashion to highly energetic particles in space, but throughout their body and not just their face. I expect that a person could not survive such an exposure and that their body would be destroyed. Even if they survived, it is highly likely they would live with crippling medical conditions and very likely develop cancer later in life.
The following is multiple choice question (with options) to answer.
What laws regulate radiation doses to which people can be exposed? | [
"voltage protection laws",
"medical regulation laws",
"radiation protection laws",
"dose regulation laws"
] | C | Radiation Protection Laws regulate radiation doses to which people can be exposed. The greatest occupational whole-body dose that is allowed depends upon the country and is about 20 to 50 mSv/y and is rarely reached by medical and nuclear power workers. Higher doses are allowed for the hands. Much lower doses are permitted for the reproductive organs and the fetuses of pregnant women. Inadvertent doses to the public are limited to 1 / 10 of occupational doses, except for those caused by nuclear power, which cannot legally expose the public to more than. |
SciQ | SciQ-4021 | biochemistry
Title: Why can't amylase break down glycogen? Amylase is an enzyme that breaks down starch in the form of amylopectin and amylose. Both amylose and amylopectin are formed by alpha glucose joined together by (1-4) and (1-6) glycosidic bonds. Glycogen is no exception, just that it has more branching. However, why is it that a google search shows that it is hydrolyzed by Glycogen Phosphorylase rather than amylase? Also, how can amylase digest both (1,6) and (1,4) glycosidic bonds?
Any help would be greatly appreciated. At an approximation the active sites of enzymes can be considered as having two aspects. The first relates to the catalysis — in this case the breaking of the glycosidic linkage. The second relates to binding the substrate. This review of the α-amylases by MacGregor et al. shows that there is a range of a-amylases, differing in this latter respect — their substrate specificity. In general there are binding sites for a varying numbers of glucose residues at either side of the bond being cleaved. This is shown in Fig. 3 of that review:
The important difference in the structure of glycogen and starch (amylopectin) — seldom mentioned in general biochemical or biology texts — is their patten of branching:
As this previous answer of mine to a different question explains, this results in a globular structure for glycogen granules in which only the ends of the chains are accessible. (The image below, from Protopedia, illustrates this better, especially if you imagine it in three dimensions.)
The following is multiple choice question (with options) to answer.
Digestive enzymes, including which enzyme, start breaking down starches into sugars? | [
"triglyceride",
"melatonin",
"amylase",
"cortisol"
] | C | Once you start eating, saliva wets the food, which makes it easier to break up and swallow. Digestive enzymes, including the enzyme amylase, start breaking down starches into sugars. Your tongue helps mix the food with the saliva and enzymes. |
SciQ | SciQ-4022 | dna, terminology
Title: Is a DNA molecule a single strand of polynucleotide or two of them linked together? Our molecular biology teacher told us that a double helix of DNA was composed of two DNA molecules linked together by hydrogen bonds. The thing is, until now, I always thought a DNA molecule was composed of two strands, those being polynucleotides, both of them being linked together. I can't find a link which is saying the same as my teacher, even if it seems technically correct to call a double helix a dimer of two DNA molecules.
I was curious to know what was the exact terminology. As you pointed out, though this may be basic biology, seeking clarification when receiving conflicting information is a good thing. Don't feel embarrassed for asking. :)
.. our molecular biology teacher told us that a double helix of DNA was composed of two DNA molecules linked together by hydrogen bonds.
Respectfully, your teacher is incorrect. A single, double-stranded DNA molecule is comprised of two helical shaped polynucleotides, and are connected together via hydrogen bonding.
Highlight of each polynucleotide
Highlight of hydrogen bonding
And just for further validation, according to Molecular Biology of the Cell, 4th ed., by Alberts B, Johnson A, Lewis J, et al.:
A DNA molecule consists of two long polynucleotide chains composed of four types of nucleotide subunits. Each of these chains is known as a DNA chain, or a DNA strand. Hydrogen bonds between the base portions of the nucleotides hold the two chains together.
So, it would seem that your teacher is referring to each polynucleotide, a.k.a. DNA strand, as a DNA molecule. Instead, she should use the verbiage: a single DNA molecule is composed of two DNA strands, which are helical-shaped polynucleotides.
The following is multiple choice question (with options) to answer.
In prokaryotes, what is composed of a single, double-stranded dna molecule in the form of a loop or circle? | [
"genome",
"chromosomes",
"rNA",
"allele"
] | A | Genomic DNA Before discussing the steps a cell must undertake to replicate, a deeper understanding of the structure and function of a cell’s genetic information is necessary. A cell’s DNA, packaged as a double-stranded DNA molecule, is called its genome. In prokaryotes, the genome is composed of a single, double-stranded DNA molecule in the form of a loop or circle (Figure 10.2). The region in the cell containing this genetic material is called a nucleoid. Some prokaryotes also have smaller loops of DNA called plasmids that are not essential for normal growth. Bacteria can exchange these plasmids with other bacteria, sometimes receiving beneficial new genes that the recipient can add to their chromosomal DNA. Antibiotic resistance is one trait that often spreads through a bacterial colony through plasmid exchange. |
SciQ | SciQ-4023 | paleontology, meteorite, mass-extinction, cretaceous, acid-rain
Title: Signatures of acid rain at KT boundary I read in Walter Alvarez' book T. Rex and the Crater of Doom
that the Earth's collision with the large meteor leading to the K-T extinction catalyzed the reaction of atmospheric oxygen and nitrogen molecules to form nitric oxide, which in turn formed highly corrosive nitric acid when combined with water. In addition the impact is thought to have volatilized huge amounts of sulfur contained in anhydrite, which in turn formed sulfuric acid.
This question refers to a thickness of $\pu{1.8m}$ for the section where iridium could be detected in the K-T boundary, suggesting that the resolution may be too low to note the effects of acid rain following the collision.
Is there evidence in the geological record of the formation of these acid species thought to be associated with the collision, say from deposits and/or effects of the ensuing acid rain? Estimated sulfur release 325 gigatonnes = 325,000 teragrams. The numbers in this diagram are in teragrams
Sulfur Cycle
so the release is $\approx 1000\times $ today's annual sulfur cycle.
I think most of the sulfur compounds would be washed into the ocean and then deposited into sediments. I can't find how much sulfur is currently in the oceans, this article says gigatons (because you can smell it). I also can't find how fast the increased sulfur would be deposited.
Another issue is that, unlike iridium, there is normally a lot of sulfur in marine deposits, so it is hard to distinguish what comes from Chicxulub.
The following is multiple choice question (with options) to answer.
What is formed when nitrogen and sulfur oxides dissolve in rain? | [
"ozone",
"acid rain",
"hail",
"toxic rain"
] | B | Acid rain is rain that has a pH less than 5. It forms when nitrogen and sulfur oxides dissolve in rain. Acid rain kills living things and damages buildings and statues. |
SciQ | SciQ-4024 | power-engineering
Title: Why are hydropower plants always wheel-shaped and not flat? Question:
Why are there no flat power generators like in the picture below, that work on the surface of shallow, but steadily flowing rivers ? (As a floating micropower plant.)
The picture shows a conveyer belt with vanes/blades(?) attached to it. The water flow moves the conveyer belt. A generator could be attached to the front and back "wheel" of the belt.
Here's a video of something similar. I would just build it on a larger river.
Why would I ask this?
There are much more flat rivers than waterfall-like structures on this planet. Using them looks like a much more non-nature-inversive, cheap solution. Having a longer surface should supply better drag by flowing water. When you want to solve a problem, the best start is to look at previous attempts. To provide some perspective, I'm doing that for you now. You are not looking at a typical hydro power plant where a dam provides a high head, and the flow is ducted onto a a francis or pelton turbine. You are describing a microhydropower installation with a floating turbine.
Floating hydrpower allows capturing some power without building a dam. The turbine could be placed in or near the middle of the river, where the current is fastest. An installation with a damn will always harvest vastly more power from the same river.
Before electrical power transmission became widespread, there used to be boat mills - workshops with machinery driven by water wheels, placed on boats.
(Boat mill in Servia, 1900, Image from lowtechmagazine page on boat mills)
Improvised versions have also been used for electricity generation.
Floating hydro power is, AFAICT, an ongoing area of developement. The two most common turbine shapes appear to be a propeller hanging from buoys:
(Image source)
... Or some sort of flat paddle wheel:
Vertical axis turbines also exist.
I think Kamran explains quite well why a propeller or a paddle wheel is used, rather than a conveyor belt. I will just add this: Look at the water wheel in the direction of flow: You want to maximise area here.
The following is multiple choice question (with options) to answer.
Hydroelectric power harnesses the energy of what? | [
"air",
"heat",
"weather",
"water"
] | D | Moving water has energy ( Figure above ). That energy is used to make electricity. Hydroelectric power harnesses the energy of water moving down a stream. Hydropower is the most widely used form of renewable energy in the world. This abundant energy source provides almost one fifth of the world’s electricity. The energy of waves and tides can also be used to produce water power. At this time, wave and tidal power are rare. |
SciQ | SciQ-4025 | species-identification, theoretical-biology, taxonomy, literature, bioluminescence
Title: Looking for the closest example of life forms similar to some mathematical patterns
Caveat: this is my first question here, it is quite interdisciplinary, but I hope to be in the correct place to ask. I am a user of Mathematics Stack Exchange since some years ago, and this question is related with some questions there (here, here whose general formula is discussed here and here).
Context: I am preparing a mathematical paper regarding a new family of dynamical systems (if you are not familiar with the concept, simplifying the idea it is a mathematical formula in which starting from a initial value, once applied to the formula the resulting value is again applied to the formula, and so on, finally the values are plotted and eventually a -sometimes interesting- pattern emerges) whose attractors (plotted patterns) in the present case seem to have unexpected pareidolic properties.
Basically some of the patterns generated by these systems show similarities with some structures of invertebrate life forms, specially insects, marine jellyfish, and zooplancton and also due to the patterns of the accumulation of points, also with life forms presenting bioluminescence properties.
For each interesting pattern so far I have tried to find the closest life form example, to compare both the model and the life form patterns.
So my target is including in the paper the closest life form similar to each mathematical pattern. Initially it is just a pareidolic coincidence, but it might be interesting if the mathematical formula can resemble models of some organic structures.
These are the ones I have been able to gather, both the model and the closest life form I found. The pictures I am using at the right side of and below the images are just for the sake of completeness (they belong to their respective owners, I do not own them, if there is any problem I will remove them, so just please let me know). The formula can be verified at the MSE links I have added at the beginning of the question and the Python code to generate them is in this link (please feel free to use it and modify it). The questions are after the examples (click to enlarge):
Patterns similar to thorax and abdomen of Bembicini wasp, head and body of Turritopsis dohrnii (inmortal jellyfish) and Tardigrade limbs:
Patters similar to Drain fly:
The following is multiple choice question (with options) to answer.
Hydras and sea anemones are examples of what form? | [
"node",
"anemone",
"lesions",
"polyp"
] | D | |
SciQ | SciQ-4026 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
Tropical, temperate, continental, and polar are all examples of what? | [
"deserts",
"lakes",
"climates",
"land formations"
] | C | Climate types are based on temperature and precipitation. A major climate type and its living things make up a biome. Climate types include tropical, temperate, continental, and polar climates. |
SciQ | SciQ-4027 | neuroscience, neuroanatomy
Likewise, the spinal chord is structured into sensory and motor regions. In summary, the spinal chord consists of: 1) cell bodies (motor, sensory, inter; grey in the picture), 2) ascending axons (blue), 3) descending axons (red). Similar to nerves, axons going up or down the spinal chord are bundled into "tracts". Sensory axons are never bundled with motor axons, making it possible to create a map of the spinal chord in cross-section.
The tracts' names might be a bit confusing at first, but on second look are actually pretty self-explanatory. They usually contain where the axons come from and where they are going in order to synapse with other neurons. E.g. the spinocerebellar tract is formed of axons coming from the spine and going to the cerebellum. Given that the cerebellum is near the brain and the spine is further down, this is obviously an ascending tract - and ascending tracts are always sensory (because sensory information never needs to be carried downwards due to the brain being at the top).
Where it gets blurry
The sensory/motor separation isn't always as clear as I've described above. In fact, nerves (bundles of axons anywhere in the body outside of the CNS) will usually contain both sensory and motor pipelines. In particular, the cranial nerves (12 of the most important nerves) all include sensory and motor components for the respective part of the body that they manage. E.g. the facial nerve contains both the sensory connections for parts of the tongue and the motor connections that control facial muscles.
Another more complex example is pain sensation, where interneurons in the spinal chord can feed back onto sensory neurons and inhibit their signals, or axons can inhibit those packed in the same nerve bundle simply due to electrical effects.
The following is multiple choice question (with options) to answer.
What is a longitudinal, flexible rod located between the digestive tube and the nerve cord? | [
"the oscillatory",
"the notochord",
"tubular gland",
"the underlain"
] | B | |
SciQ | SciQ-4028 | fluid-dynamics, pressure, fluid-statics
Altitude
Today's astronomical observatories are constructed at locations where the altitude is 4 to 5 kilometers, such as on the highest mountain tops of the Hawaiian islands.
Astronomers have to acclimatize in order to work at an altitude like that. The acclimatization period allows the body to adapt to the lower air pressure (higher amount of red blood cells per unit of volume of blood.) Without acclimatization people are prone to getting altitude sickness.
This illustrates that with height above ground level there is a rapid decline in air density.
Air is compressible, and at ground level the air must have sufficient pressure to carry the entire column of air above it.
So we have that the case of atmospheric pressure is quite intuitive. Gradient in density and gradient in pressure going hand in hand.
In the case of a fluid column we have that the fluid is hardly compressible. So it's harder to get a feel that that there is a significant pressure gradient all the same.
In a column of fluid the pressure (as a function of height) is definitely not uniform. There is a gradient in pressure, consistent with the weight of the fluid column above it.
A fluid
As you mention: a fluid (be it a gas or a liquid) exerts a pressure by way of the constituent molecules bumping against the surface of the object that is immersed in the fluid.
The molecules of a gas (at 1 atmosphere of pressure) have a lot of room to travel.
Water does not compress much under pressure, but it does compress a little.
Water at 1 atmosphere of pressure will have its molecules bumping against the surface of an immersed object at a rate such that the pressure exerted is 1 atmosphere of pressure.
Pressurizing the water reduces how much wiggle room there is for the thermal motion of the water molecules.
Imagine you are pacing back and forth in a room, using the walls of the room to reverse your direction of motion. Pacing from wall to wall is like the life of an air molecule.
Imagine you are a molecule of liquid: you can no longer do any pacing; you are down to a vibration in place. Now increase density: less wiggle room, so the amplitude of your vibration is smaller. But you still have the same velocity from bump to bump, so the amount of bumps per unit of time is larger. This higher frequency of bumps is the higher pressure.
The following is multiple choice question (with options) to answer.
At high altitudes, acclimatization increases red blood cells, so there is more what to help transport the available oxygen? | [
"leukocytes",
"plasma",
"platelets",
"hemoglobin"
] | D | Acclimatization Especially in situations where the ascent occurs too quickly, traveling to areas of high altitude can cause AMS. Acclimatization is the process of adjustment that the respiratory system makes due to chronic exposure to a high altitude. Over a period of time, the body adjusts to accommodate the lower partial pressure of oxygen. The low partial pressure of oxygen at high altitudes results in a lower oxygen saturation level of hemoglobin in the blood. In turn, the tissue levels of oxygen are also lower. As a result, the kidneys are stimulated to produce the hormone erythropoietin (EPO), which stimulates the production of erythrocytes, resulting in a greater number of circulating erythrocytes in an individual at a high altitude over a long period. With more red blood cells, there is more hemoglobin to help transport the available oxygen. Even though there is low saturation of each hemoglobin molecule, there will be more hemoglobin present, and therefore more oxygen in the blood. Over time, this allows the person to partake in physical exertion without developing AMS. |
SciQ | SciQ-4029 | immunology, pathology, pathophysiology
SRC
You can see in healthy phagocytes that through one of two pathways, protein antigens end up displayed on HLA molecules for cellular immunity to take over. Option B is that another cell like a macrophage detects distress signals from the infected cell and induces cell death in it through receptors or oxidative burst. In the case of Salmonella, HLA expression is down-regulated and oxidative burst can be inhibited so localized, infected antigen-presenting cells cant mount an effective response.
That's not to say everything is de-regulated early on. If you succeed in antigen presentation or innate killing (perhaps a non-pathogenic strain), you will resolve the infection as seen in the above figure: a combination of T-mediated killing, B-mediated killing, NK-mediated killing, and generalized inflammation.
In the chronic case, the pathogen will have escaped the primary immune response, but the system will attempt to continue to resolve the infection. This can lead to a number of things: cellular anergy, cellular hyperactivity, sequestration (see granuloma), chronic inflammation & tissue damage, and so forth. The following diagram is predicated upon viral infections but the immunology is largely similar:
SRC
There are changes to the system that are a result of over-exposure to antigen, and an inability to clear that stimulation. The best way to explain it is that chronic stimulation leads to both hyperactivity and suppression. The constant presence of effector molecules like TNF-a leads to a persistent state of tissue inflammation, which is bad for the tissue, but taken together with the persistent presence of antigen, this may lead to dysfunctional responses by lymphocytes (3).
A particularly virulent infection may be impossible for your immune system to clear without assistance, then, requiring the intervention of gram-negative antibiotics, for example.
The following is multiple choice question (with options) to answer.
What type of systemic response involves lymphocytes? | [
"inflammation",
"immune",
"natural",
"chronic"
] | B | There are two different types of immune responses. Both types involve lymphocytes. However, one type of response involves B cells. The other type involves T cells. |
SciQ | SciQ-4030 | solar-system, comets
Title: How does a comet form? As the title explains,
How does a comet form?
What are the elements, what is a comet composed of?
Why didn't they become part of planets, moons or asteroids?
Comets are some of the material left over from the formation of the planets. Our entire solar system, including comets, was created by the collapse of a giant, diffuse cloud of gas and dust about 4.6 billion years ago. Much of the matter merged into planets, but some remained to form small lumps of frozen gas and dust in the outer region of the solar system, where temperatures were cold enough to produce ice.
A comet is generally considered to consist of a small nucleus embedded in a nebulous disk called the coma. the nucleus, containing practically all the mass of the comet, is a “dirty snowball” conglomerate of ices and dust.For one, of the observed gases and meteoric particles that are ejected to provide the coma and tails of comets, most of the gases are fragmentary molecules, or radicals, of the most common elements in space: hydrogen, carbon, nitrogen, and oxygen. The radicals, for example, of CH, NH, and OH may be broken away from the stable molecules CH4 (methane), NH3 (ammonia), and H2O (water), which may exist as ices or more complex, very cold compounds in the nucleus.
3.Many astronomers believe that these small objects never became planets or other large objects because of the gravity of the large planets. For example, the pull of Jupiter's kept 'stirring the pot' of the asteroid belt, so that the gravitational pull of the asteroids on each other was constantly being disturbed.
For the Kuiper belt and Oort cloud, there is a popular theory called 'planetary migration.' The main idea behind this theory is that the large outer planets of our Solar System started out much closer to the Sun when the Solar System was formed. As they migrated outward through the cloud of small objects still there, the gravity of these large planets pulled a lot of the small objectsout of their orbits. Some were pulled into the planets, and some were flung far into the outer reaches of the Solar System.
The objects that were flung very far out by Jupiter became the Oort cloud. The object that were not flung out quite as far by the movement of Neptune became the Kuiper belt.
Source
The following is multiple choice question (with options) to answer.
What was the first object to form in the solar system? | [
"earth",
"sun",
"moon",
"jupiter"
] | B | The Sun was the first object to form in the solar system. Gravity pulled matter together to the center of the disk. Density and pressure increased tremendously. Nuclear fusion reactions begin. In these reactions, the nuclei of atoms come together to form new, heavier chemical elements. Fusion reactions release huge amounts of nuclear energy. From these reactions a star was born, the Sun. |
SciQ | SciQ-4031 | physical-chemistry, solubility, enthalpy
Regarding why the substance is soluble why its dissolution is endothermic, you have to remember that the reaction takes place if $\Delta_\mathrm r G$ is favourable (i.e. negative), and $\Delta_\mathrm r G = \Delta_\mathrm r H - T \Delta_\mathrm r S$. Overall the free energy must be negative for dissolution to occur (on a thermodynamic basis; kinetics are another issue), not the enthalpy.
The following is multiple choice question (with options) to answer.
Some materials have negative heats of solution; the dissolution of one of these solutes in water is called? | [
"exothermic process",
"endothermic process",
"ionized process",
"acetylene process"
] | A | Some materials have negative heats of solution; the dissolution of one of these solutes in water is an exothermic process. Heat is released, causing a net increase in the temperature of the solution. Conversely, other substances have positive heats of solution. For example, the dissolution of potassium nitrate in water is an endothermic process. The resulting absorption of energy causes the solution to become colder. Calculations involving heats of solutions follow the same basic approach that we have used with other enthalpy problems. |
SciQ | SciQ-4032 | 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.
Where are most white blood cells made? | [
"plasma",
"lungs",
"heart tissue",
"the bone marrow"
] | D | White blood cells (WBCs) are usually larger than red blood cells. They do not have hemoglobin and do not carry oxygen. White blood cells make up less than one percent of the blood's volume. Most WBCs are made in the bone marrow, and some mature in the lymphatic system. There are different WBCs with different jobs. WBCs defend the body against infection by bacteria, viruses, and other pathogens . WBCs do have a nucleus and other organelles. |
SciQ | SciQ-4033 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
Blood flows from the right atrium to the right ventricle, where it is pumped into the what? | [
"respiratory system",
"bronchial circulation",
"kidneys",
"pulmonary circuit"
] | D | Figure 19.4 Dual System of the Human Blood Circulation Blood flows from the right atrium to the right ventricle, where it is pumped into the pulmonary circuit. The blood in the pulmonary artery branches is low in oxygen but relatively high in carbon dioxide. Gas exchange occurs in the pulmonary capillaries (oxygen into the blood, carbon dioxide out), and blood high in oxygen and low in carbon dioxide is returned to the left atrium. From here, blood enters the left ventricle, which pumps it into the systemic circuit. Following exchange in the systemic capillaries (oxygen and nutrients out of the capillaries and carbon dioxide and wastes in), blood returns to the right atrium and the cycle is repeated. |
SciQ | SciQ-4034 | reproduction, asexual-reproduction
Title: can self-fertilization in flowers be called asexual reproduction? Suppose a flower having both male and female reproductive parts is self-fertilized then can this be called asexual reproduction...?I'm quite confused cause in this case the fusion of male and female gametes do take place but again the gametes are from the same parent....please help. According to this article from Berkeley, asexual reproduction is:
Any reproductive process that does not involve meiosis or syngamy
Using this definition of asexual reproduction and knowing self-fertilization involves meiosis and syngamy, it is not asexual.
The following is multiple choice question (with options) to answer.
What are the male gametes called? | [
"pollen",
"sperm",
"urea",
"cytoplasm"
] | B | Gametogenesis may differ between males and females. Male gametes are called sperm . Female gametes are called eggs . In human males, for example, the process that produces mature sperm cells is called spermatogenesis . During this process, sperm cells grow a tail and gain the ability to “swim,” like the human sperm cell shown in Figure below . In human females, the process that produces mature eggs is called oogenesis . Just one egg is produced from the four haploid cells that result from meiosis. The single egg is a very large cell, as you can see from the human egg in Figure below . |
SciQ | SciQ-4035 | genetics, human-genetics
Title: skin colouration in thalassemia Now when i was studying about thalassemia, I read that anaemia is its major characterstic. I can understand that fact. But it was also written that the skin gets pale.
Wikipedia says that the skin turns yellowish.
I want to ask firstly is it that the skin gets darker when the affected person is exposed to sun and is otherwise pale?
And also why does the skin turn yellow/pale in the first place? Does that have to do something with Iron? Thalassemia is a genetic disease, in which either the alpha- or the beta-globins are missing or mutated. The hemoglobin of the blood is a protein complex which in adults consists of 2 alpha- and 2 beta-globin subunits. The ratio of these proteins needs to be exactly right, if one of them isn't produced enough or even missing, this leads to non-functional hemoglobin and subsequently abnormal erythrocytes.
These are then removed and broken down in the spleen (which is often abnormally enlarged), which also leads to the breakdown of the non-functional hemoglobin. The main product of the hemoglobin breakdown is Bilirubin, which is yellow. The yellow skin is a sign of jaundice, which is caused by high levels of Bilirubin in the blood.
The cause for the high Bilirubin levels in the blood of Thalassemia patients is the abnormal high rate of Hemoglobin breakdown.
The following is multiple choice question (with options) to answer.
What in hemoglobin gives red blood cells their red color? | [
"calcium",
"barium",
"iron",
"lead"
] | C | Red blood cells are shaped like flattened disks. There are trillions of red blood cells in your blood. Each red blood cell has millions of molecules of hemoglobin. Hemoglobin is a protein that contains iron. The iron in hemoglobin gives red blood cells their red color. It also explains how hemoglobin carries oxygen. The iron in hemoglobin binds with oxygen molecules so they can be carried by red blood cells. |
SciQ | SciQ-4036 | Can you now relate now $\alpha, \beta, \gamma$ with $p$ and $q$? Do we get any relation between $\alpha, \beta, \gamma$?
Yes, from $$(x-\alpha)(x-\beta)(x-\gamma)=x^3+px+q$$ one obtains $\alpha \beta + \alpha \gamma + \beta\gamma= p$, $\alpha \beta \gamma =-q$, and $\alpha + \beta + \gamma=0$. Due to this latter relation, one can also write $(\alpha + \beta + \gamma)^2=0$, i.e., $\alpha^2 +\beta^2 +\gamma^2=-2(\alpha \beta + \alpha \gamma + \beta\gamma)=-2p$ and also $(\alpha \beta)^2 + (\alpha \gamma)^2 + (\beta \gamma)^2=(\alpha \beta + \alpha \gamma + \beta \gamma)^2-2(\alpha \beta\gamma)(\alpha +\beta+\gamma)=(\alpha \beta + \alpha \gamma + \beta \gamma)^2=p^2$
After this, consider a degree 3 function that has roots $\frac{\alpha \beta}{\gamma}, \frac{\alpha \gamma}{\beta}, \frac{\alpha \gamma}{\beta}$:
The following is multiple choice question (with options) to answer.
Alpha, beta and gamma are three types of what? | [
"convection",
"radiation",
"mutation",
"directions"
] | B | Early researchers in radioactivity found that the emissions from radioactivity could be classified into three distinct types according to their penetrating power. One type of radiation could barely penetrate a sheet of paper. The second type could pass through as much as 3 mm of aluminum. The third type was extremely penetrating and could pass through several centimeters of lead. They named these three types of radiation alpha , beta , and gamma respectively. Eventually, each type of radiation was further identified. Alpha particles are the nuclei of helium atoms, . Beta particles are electrons, and gamma rays are very high energy photons (even higher energy than x-rays). |
SciQ | SciQ-4037 | evolution, vision, neurophysiology
Title: What is the evolutionary advantage of red-green color blindness? Red-green colorblindness seems to make it harder for a hunter-gatherer to see whether a fruit is ripe and thus worth picking.
Is there a reason why selection hasn't completely removed red-green color blindness? Are there circumstances where this trait provides an evolutionary benefit? Short answer
Color-blind subjects are better at detecting color-camouflaged objects. This may give color blinds an advantage in terms of spotting hidden dangers (predators) or finding camouflaged foods.
Background
There are two types of red-green blindness: protanopia (red-blind) and deuteranopia (green-blind), i.e., these people miss one type of cone, namely the (red L cone or the green M cone).
These conditions should be set apart from the condition where there are mutations in the L cones shifting their sensitivity to the green cone spectrum (deuteranomaly) or vice versa (protanomaly).
Since you are talking color-"blindness", as opposed to reduced sensitivity to red or green, I reckon you are asking about true dichromats, i.e., protanopes and deuteranopes. It's an excellent question as to why 2% of the men have either one condition, given that:
Protanopes are more likely to confuse:-
Black with many shades of red
Dark brown with dark green, dark orange and dark red
Some blues with some reds, purples and dark pinks
Mid-greens with some oranges
Deuteranopes are more likely to confuse:-
Mid-reds with mid-greens
Blue-greens with grey and mid-pinks
Bright greens with yellows
Pale pinks with light grey
Mid-reds with mid-brown
Light blues with lilac
The following is multiple choice question (with options) to answer.
Red-green colorblindness is an example of what kind of trait? | [
"fatal",
"dominant",
"adaptive",
"sex-linked"
] | D | One example of a sex-linked trait is red-green colorblindness. People with this type of colorblindness cannot tell the difference between red and green. They often see these colors as shades of brown ( Figure below ). Boys are much more likely to be colorblind than girls ( Table below ). This is because colorblindness is a sex-linked, recessive trait. |
SciQ | SciQ-4038 | temperature, sun, light, equator, insolation
Title: Why does the intensity of sunlight depend on your latitude? People at the equator get to bask in more sunlight than Santa Clause and other inhabitants of the arctic regions. Not quite as pronounced, but they get more than me too.
Why is the sunlight more intense closer to the equator and less intense farther away from it?
When I posted this question, I was not thinking about the possible ambiguities, such as "Are you talking about the exposure across a surface area with some non-perpendicular angle to the sun," or "Are you talking about the light gathered by an optic facing the sun?" There is a difference. Since "basking in sunlight" was the example use case, let us assume exposure across a surface area which is lying on the ground. As noted in the comments, this answer applies to things like sun-bathing and solar panels, but it does not apply so much to a specific point-receptor like an eyeball. If all objects in question are pointing directly at the sun, then the angle of incidence is equal for all of them and this answer does not apply.
For an optic facing its target, the amount of atmosphere that the light passes through is a very large influencer. At higher latitudes, the sun is not directly overhead, and so the light is not coming straight down through the path of least atmosphere. Instead, it comes in at an angle, passing through more of the atmosphere before it gets to you.
For sun-bathers, solar panels, and the ground in general, the sunlight absorbed and reflected does depend very much on what is described in this answer. For that reason, more expensive solar panels are mounted on devices which alter their angle to face the sun for increased light exposure. And a sun-bather could likewise increase their exposure by mounting their platform at an angle. This is the direction the rest of the answer will take.
The answer is similar to the answer to some other questions, such as "Why does the solar power intensity change with the season?" and "Why does the solar intensity change with the height of the sun in the sky (ie: with the time of day)?"
The very short, non-technical version (tl;dr)
Each unit (think "beam of sunlight") is spread over a larger area.
That might not seem intuitive at first, but that is the answer in a nutshell. To see why, continue to the long version.
The following is multiple choice question (with options) to answer.
What kind of radiation is greatest at the equator and lessens toward the poles? | [
"large radiation",
"small radiation",
"solar radiation",
"lunar raditation"
] | C | The amount of solar radiation a place receives is greatest at the Equator and lessens toward the poles. |
SciQ | SciQ-4039 | electrons, charge, quasiparticles, leptons
Title: How do electrons get a charge? Electrons belong to a group of elementary particles called leptons. There are charged and neutral leptons. And electron is the charged one. But how come it got charged?
The negative or positive charges were assigned by convention. But it is a fact that electrons are charged. My question is why electrons? and not neutrons?
Also while reading http://en.wikipedia.org/wiki/Electron, I saw that "Independent electrons moving in vacuum are termed free electrons. Electrons in metals also behave as if they were free. In reality the particles that are commonly termed electrons in metals and other solids are quasi electrons, quasiparticles, which have the same electrical charge, spin and magnetic moment as real electrons but may have a different mass ( or Effective mass - extra mass that a particle seems to have while interacting with some force )."
What does this mean? Your question touches the question of ontology in particle physics. Historically we are used to be thinking of particles as tiny independent entities that behave according to some laws of motion. This stems from the atomistic theory of matter, which was developed some two thousand years ago from the starting point of what would happen if we could split matter in ever smaller parts. The old Greeks came to the conclusion that there had to be a limit to that splitting, hence the atom hypothesis was born.
This was just a philosophical idea, of course, until around the beginning of the 19th century we learned to do chemistry so well that it became obvious that the smallest chunks that matter can be split into seemed to be the atoms of the periodic table. A hundred years later we realized that atoms can be split even further into nuclei and electrons. What didn't change was this idea that each chunk had its own independent existence.
This idea ran into a deep crisis during the early 20th century when we discovered the first effects of quantum mechanics. It turns out that atoms and nuclei and electrons do not, at all, behave like really small pieces of ordinary matter. Instead, they are behaving radically different, so different, indeed, that the human imagination has a hard time keeping up with their dynamic properties.
The following is multiple choice question (with options) to answer.
What are atoms or groups of atoms called which carry and electrical charge? | [
"molecules",
"ions",
"protons",
"electrons"
] | B | Atoms or groups of atoms that carry an overall electrical charge are referred to as ions. Cations can be formed when a neutral species loses electrons, while anions are formed when a neutral species gains electrons. |
SciQ | SciQ-4040 | acid-base
Title: What is called a salt? While I was doing experiments in my school days, they gave me different substances with the combination of base and acid radicals, for example ammonium nitrate and zinc chloride and they seldom called it a salt.
But actually a salt is a NaCl as far as I know.
So My Question is: Actually, what is called a salt?
Why do they call the acid and basic radical a salt? I think what confuses you is that 'salt' has two meanings: In the every day sense it means table salt (which has the formula NaCl) but in the chemical sense it means a certain way for particles to hold together and form a tangible substance.
I'd define the latter as any periodic arrangement/lattice (see e.g. here ) of particles held together by ionic bonds.
The positive ion is almost always a metal, the negative one can be anything (so usually either a halogen (those lack only one valence electron to have a full shell, see e.g. Cl) or a (smallish) molecule-ion like SO4^2−)
base and acid radicals
I really don't see much connection between salts and either bases/acids and radicals. Do consider that not all ions are bases/acids and all radicals are highly reactive. It would rather be an edge case to have a salt with a radical in it; most salts have ions with energetically favourable number of electrons (as a rough rule this means all "electron shells" are either full or empty.)
NaCl is a good example.
Because different sized salt crystals still have extremely similar behaviour, the salt formulas express only the ratio of anions and cations. Realize that on the whole salts are neutral.
Why do they call the acid and basic radical a salt?
A single kind of particle is never called a salt, salt means an arrangement of two ions of different polarity. I guess some lab 'recipes' have sloppy language if something is provided as a salt, but only one component is important for the reaction.
Perhaps I can give a better answer I understood what you mean by radical in this context.
The following is multiple choice question (with options) to answer.
What are the salts of fatty acids called? | [
"creams",
"soaps",
"malts",
"dyes"
] | B | Soaps and Detergents Pioneers made soap by boiling fats with a strongly basic solution made by leaching potassium carbonate, K2CO3, from wood ashes with hot water. Animal fats contain polyesters of fatty acids (long-chain carboxylic acids). When animal fats are treated with a base like potassium carbonate or sodium hydroxide, glycerol and salts of fatty acids such as palmitic, oleic, and stearic acid are formed. The salts of fatty acids are called soaps. The sodium salt of stearic acid, sodium stearate, has the formula C17H35CO2Na and contains an uncharged nonpolar hydrocarbon chain, the C17H35— unit, and an ionic carboxylate group, the — CO 2 − unit (Figure 11.32). |
SciQ | SciQ-4041 | orbitals, electronic-configuration
Title: Why is there an exponent 4 after the brackets in sp3? My professor wrote an electron configuration for carbon as: 1s2 (sp3)4
I thought it was just 1s2 sp3 where did the 4 come from? The electron configuration of carbon is canonically written as 1s22s22p2. What you now can do is invoke orbital hybridization and combine the electrons in the 2s and 2p orbitals. Then you get sp3 hybrid orbitals with a total of 4 electrons in them. The 1s electrons stay where they are. To mark the new hybrid orbitals as separate, you put brackets around them.
You then end up with an electronic configuration of 1s2(2sp3)4.
The following is multiple choice question (with options) to answer.
What type of numbers specify the arrangement of electrons in orbitals? | [
"fusion numbers",
"ionic numbers",
"quantum numbers",
"stream numbers"
] | C | Quantum numbers specify the arrangements of electrons in orbitals. |
SciQ | SciQ-4042 | quantum-mechanics, newtonian-mechanics
Title: What happens to a radioactive element or isotope's electrons when it undergoes alpha decay? It seems to make sense that when an atom loses two protons, it would lose two electrons as well, but I don't actually know what happens. It is complicated and we ignore it, but your intuition is right. When the nucleus loses an alpha particle its charge decreases by two. The atomic physicists now claim their job is done and don't care. The solid state physicists don't consider radioactivity, so they don't care either. If it is an atom floating freely in space, two electrons will move off in some direction, but who cares? If it is an atom in a solid crystal, you should ask how much the recoil moves the atom and whether it dislocates the crystal.
The following is multiple choice question (with options) to answer.
What do atoms become if they lose or gain electrons? | [
"ions",
"particles",
"toxins",
"particulates"
] | A | Atoms are electrically neutral, but if they lose or gain electrons they become charged particles called ions. |
SciQ | SciQ-4043 | inorganic-chemistry, transition-metals
Title: Can we classify all the d-block elements as transition metals? I thought that properties of d-block elements are transitional between those of s-block and p-block elements, and that is the reason for calling them transition metal.
My textbook says that not all d block elements are called transition metals.
My doubts:
What are these non-transition metals that are in d-block?
Why are these specific elements not called transition metals? The idea that the properties of d-block elements are transitional between those of s-block and p-block elements, and that is the reason for calling them transition element. It is absolutely correct, but the thing is transition metals are defined as slightly different manner.
Definition of a transition metal/Criteria for an element to be a transition metal
A transition metal is one which forms one or more stable ions which have incompletely filled d orbitals
Appreciate that the general electronic configuration (EC) for d-block elements are slightly different for those of transition metals.
EC of d-block elements: $\mathrm{(n-1)d^{1-10}ns^{1-2}}$
EC of transition metal/ion: $\mathrm{(n-1)d^{1-9}ns^{1-2}}$
Some examples of elements which are in d-block but not a transition metal
Scandium has the electronic structure $\mathrm{[Ar] 3d^{1} 4s^2}$. When it forms ions, it always loses the 3 outer electrons and ends up with an argon structure. The $\ce{Sc^{3+}}$ ion has no d-electrons and so does not meet the definition.
Zinc has the electronic structure $\mathrm{[Ar] 3d^{10} 4s^2}$. When it forms ions, it always loses the two $\mathrm{4s}$ electrons to give a 2+ ion with the electronic structure $\mathrm{[Ar] 3d^{10}}$. The zinc ion has full d-levels and does not meet the definition either.
There's a small thing that one must take into account that some elements are capable of forming multiple metal ions. In those cases we must consider more common ion (the most stable one).
The following is multiple choice question (with options) to answer.
What is the breakdown of unstable elements into stable elements called? | [
"radioactive decay",
"initial decay",
"thermal decay",
"radioactive decrease"
] | A | Radioactive decay is the breakdown of unstable elements into stable elements. To understand this process, recall that the atoms of all elements contain the particles protons, neutrons, and electrons. |
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