source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-6944 | inorganic-chemistry, ions, identification
Title: Identifying a quadruply charged anion containing three carbon atoms
This linear polyatomic ion containing three atoms of carbon has a negative four charge and is only found bonded with lithium and magnesium.
Could anyone identify this for me? It's from a quiz bowl clue that doesn't have the answer with it.
Sesquicarbide
A quick Google search suggests that $\ce{Li4C3}$ is a real compound, but based on what I saw in the links, it probably is not ionic in the same way that lithium acetylide $\ce{Li2C2}$ is.
$\ce{Mg2C3}$ appears to be the formula for magnesium carbide, or at least a magnesium carbide.
A carbide is a binary compound of carbon and a less electronegative element, usually a metal or metalloid. Carbide is also a generic name for mono- and polyatomic anions containing only carbon. The following ions would all carbide ions: $\ce{C^{4-}, C2^2-, C2^{4-}, C2^{6-}, C3^{4-}, C3^{6-1}, C3^{8-}}$, etc.
The special name of three of these carbide ions are:
$\ce{C^{4-}}$ - Methide
$\ce{C2^{2-}}$ - Acetylide
$\ce{C3^{4-}}$ - Sesquicarbide
The following is multiple choice question (with options) to answer.
Many ionic compounds with relatively large cations and a 1:1 cation:anion ratio have this structure, which is called the what? | [
"hydrocarbon structure",
"cesium chloride structure",
"analogous structure",
"boron chloride structure"
] | B | Common Structures of Binary Compounds As shown in part (a) in Figure 12.8 "Holes in Cubic Lattices", a simple cubic lattice of anions contains only one kind of hole, located in the center of the unit cell. Because this hole is equidistant from all eight atoms at the corners of the unit cell, it is called acubic hole. An atom or ion in a cubic hole therefore has a coordination number of 8. Many ionic compounds with relatively large cations and a 1:1 cation:anion ratio have this structure, which is called the cesium chloride structure (Figure 12.9 "The Cesium Chloride Structure") because CsCl is a common example. |
SciQ | SciQ-6945 | thermodynamics, special-relativity, mass
Consequently, when you shift energy from potential to kinetic in the box, the observed mass from the outside doesn't change.
Instead, the reason that the object at absolute 0 has an "increasing entropy" is purely due to thermal energy transfer with its surroundings, which will appear as energy -- hence mass -- going into the box. Measuring the mass very carefully will, as John Rennie says in a comment to your question, reveal a change in the total internal energy, but not anything deep or fundamental about the entropy contained within it: it could have gotten that mass because its temperature increased, but it could also have gotten that mass in the form of positronium (electron-positron pairs) which are a tenth of a microsecond away from exploding into gamma rays. You don't really know just by looking at the mass of the box which has happened.
The following is multiple choice question (with options) to answer.
What property increases as an object's mass increases, making a full box harder to push than an empty one? | [
"inertia",
"weight",
"gravity",
"magnetism"
] | A | The inertia of an object depends on its mass. Objects with greater mass also have greater inertia. Think how hard it would be to push a big box full of books, like the one in Figure below . Then think how easy it would be to push the box if it was empty. The full box is harder to move because it has greater mass and therefore greater inertia. |
SciQ | SciQ-6946 | climate-change, sea-level
Global sea level has risen by about 8 inches since reliable record keeping began in 1880. It is projected to rise another 1 to 4 feet by 2100.
Projecting future rates of sea level rise is challenging. Even the most sophisticated climate models, which explicitly represent Earth’s physical processes, cannot simulate rapid changes in ice sheet dynamics, and thus are likely to underestimate future sea level rise. In recent years, “semi-empirical” methods have been developed to project future rates of sea level rise based on a simple statistical relationship between past rates of globally averaged temperature change and sea level rise. These models suggest a range of additional sea level rise from about 2 feet to as much as 6 feet by 2100, depending on emissions scenario.
Recent projections show that for even the lowest emissions scenarios, thermal expansion of ocean waters and the melting of small mountain glaciers will result in 11 inches of sea level rise by 2100, even without any contribution from the ice sheets in Greenland and Antarctica. This suggests that about 1 foot of global sea level rise by 2100 is probably a realistic low end. On the high end, recent work suggests that 4 feet is plausible.,,,, In the context of risk-based analysis, some decision makers may wish to use a wider range of scenarios, from 8 inches to 6.6 feet by 2100., In particular, the high end of these scenarios may be useful for decision makers with a low tolerance for risk
In the next several decades, storm surges and high tides could combine with sea level rise and land subsidence to further increase flooding in many of these regions. Sea level rise will not stop in 2100 because the oceans take a very long time to respond to warmer conditions at the Earth’s surface. Ocean waters will therefore continue to warm and sea level will continue to rise for many centuries at rates equal to or higher than that of the current century
The following is multiple choice question (with options) to answer.
What will happen to sea levels due to increased global temperatures? | [
"reverse",
"Drop",
"surge",
"rise"
] | D | This increase in global temperature will cause the sea level to rise. It is also expected to produce an increase in extreme weather events and change the amount of precipitation. Global warming may also cause food shortages and species extinction. |
SciQ | SciQ-6947 | botany, terminology, nomenclature
Regnum Animale: the animals;
Regnum Vegetabile: the plants;
Regnum Lapideum: the minerals (you read it right).
Note that, in this classification, "animals" correspond to what nowadays we call animals and protozoans, and "plants" correspond to what nowadays we call plants, algae, fungi and bacteria.
You have to keep in mind that this book was first published in 1735, well before the evolutionary biology being proposed in the XIX century and established in the XX century. Therefore, it is a book published when fixism was the current paradigm, full of mentions to the scala naturae.
So, the plants (as well as the animals) showed a continuum of species, going to the lower plants (the bacteria) to the higher plants (the flowering ones). It's worth mentioning again that, by that time, bacteria were plants: Phylum Schyzophyta, to be more precise.
Thus, we have "lower plants" and "higher plants", "lower animals" and "higher animals", as well as "lower minerals" and "higher minerals"!
Unfortunately, this terminology is so embedded in the biological sciences that even today, as I mentioned, we struggle to get rid of it.
Just drop "higher plants", whatever it means
As your Wikipedia link says, "higher plants" is a synonym of vascular plants. However, there are a lot of problems here:
First, this is a remnant of the scala naturae and, just because of that, should be avoided. Think of it as a meaningless term, just like "more evolved organism".
Second, there is no clear and indisputable definition of what is a "higher" plant. Some authors used to define the "higher plants" as the Angiosperms only, or the seed plants (Angiosperms + Gymnosperms), or the vascular plants (Angiosperms, Gymnosperms and Pteridophyta).
For instance, in lusophone biology books, it was very common a division in three groups:
lower plants: bacteria and algae;
intermediate plants: bryophytes and pteridophytes;
higher plants: gymnosperms and angiosperms.
The following is multiple choice question (with options) to answer.
Sea-lilies, sea cucumbers and sea stars fall into what class of organism? | [
"echinoderms",
"mollusks",
"snakes",
"crabs"
] | A | While almost all echinoderms live on the sea floor, some sea-lilies can swim at great speeds for brief periods of time, and a few sea cucumbers are fully floating. Some echinoderms find other ways of moving. For example, crinoids attach themselves to floating logs, and some sea cucumbers move by attaching to the sides of fish. |
SciQ | SciQ-6948 | 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.
What kind of rock forms when material such as gravel, sand, silt or clay is compacted and cemented together? | [
"ingenious",
"sedimentary",
"limestone",
"craters"
] | B | 2. Sedimentary rocks form when sediments are compacted and cemented together ( Figure below ). These sediments may be gravel, sand, silt or clay. Sedimentary rocks often have pieces of other rocks in them. Some sedimentary rocks form the solid minerals left behind after a liquid evaporates. |
SciQ | SciQ-6949 | quantum-mechanics, optics, electrons
Title: Why can't an electron be observed? I was watching a show on Netflix hosted by Neil Degrasse Tyson and he mentioned that one of the fundamental particles that we know of, the electron, is something we have never even observed directly. Why haven't we done so? Is it impossible? I know this is the easy answer to any question, but is it because our tech isn't advanced enough yet? Define "observe"
The Webster, the options for science are:
a: to watch carefully especially with attention to details or behavior for the purpose of arriving at a judgment
b: to make a scientific observation on or of
And on "observation:
a: an act of recognizing and noting a fact or occurrence often involving measurement with instruments
b: a record or description so obtained
How do we observe a cloud? Light from the sun scatters off the H2O of the cloud and hits our eye. To observe it scientifically one takes pictures, or videos to study its time evolution. Is the cloud on the video "observing a cloud"?
Here is a bubble chamber picture of an electron:
The electron has scattered off atoms in the chamber ionizing them and the bubbles are formed where the ions were. It is turning in the magnetic field imposed and is losing energy from the scatters. In contrast to the cloud picture, it is not light that scatters off the object, but the object scatters off matter, and light of that path is recorded. It is a more complicated path to a picture, but there is still a one to one correspondence of the object called electron, with the picture which we call observation.
Please note that for the dimensions of the bubble chamber bubbles (microns) and the momentum of the electron in the picture, some MeV/c, satisfy the Heisenberg Uncertainty Principle, and thus within these dimension the electron can be considered in its form as a quantum mechanical "particle", with attributes of a classical particle.
We also "see" electrons directly in sparks, our eyes and brain are not equipped to see the light as clearly as the light reflected from the cloud, but this is a limitation of our biology, our instruments can.
So I think that the statement is vacuous.
Edit after comment
Do you think it would ever be possible to make something that works like a camera to take a snapshot of a single electron
Searched the net and it has been done.
The following is multiple choice question (with options) to answer.
In science, we need to make observations on various phenomena to form and test what? | [
"assumptions",
"hypotheses",
"variations",
"theories"
] | B | In science, we need to make observations on various phenomena to form and test hypotheses. Some phenomena can be found and studied in nature, but scientists often need to create an experiment . Experiments are tests under controlled conditions designed to demonstrate something scientists already know or to test something scientists wish to know. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results. The process of designing and performing experiments is a part of the scientific method. |
SciQ | SciQ-6950 | water-resources
Location
This plant requires a hot location with large area of cheap land by the ocean and a relatively consistent wind.
Stage 1 - Wave Pump
A wave-powered pump raises sea water into a large lake on land. Here is an example of a direct wave-powered pump, other types of wave power harnessing typically convert mechanical motion into electricity. However, that motion can be easily used to directly drive a pump.
Stage 2 - Evaporation Lake
The evaporation lake is a large shallow area, covered in a greenhouse-like way to aid evaporation. The sea-water flows away from the ocean along channels in the lake-bed then back again towards the ocean in the next adjacent channel where it drains back into the sea. This prevents the build-up of deposits as the returning sea-water will take them with it and return to the sea more concentrated. The roof may contain Fresnel lenses or other solar concentrators to help evaporation.
A wind-catching tower blows air across the lake to lower air pressure and aid in evaporation. This tower could be like those used in Masdar City, or a standard wind turbine tower with either electrical or direct transmission to a series of fans. The result is a continuous airflow across the lake which carries the water vapor to the far side where it is channeled up a wide column into the next stage.
Stage 3 - Condensing Tower
The water vapor is channeled up a large column to a condensing chamber high on the tower. Here, a series of fins are cooled by a heat-pump driven directly by a wind-turbine on top of the tower. the water condenses on the fins and drains into a fresh-water tank near the top of the tower.
Stage 4 - Power Generation
The water from the condensing tower is lowered to a height suitable for a standard water-tower through one or more water turbines to generate power.
Stage 5 - Filtering and treatment
The salty sea-air will also condense on the fins, and there may be small airborne particles and particles from wear on stages within this process that get into the water, so it will probably need further filtering and treatment to make it drinkable. Some of the power from the water turbine may be used for this.
There you have it, you have clean water, above ground level so pressure is already available, and hopefully some excess electricity and cool dry air as by-products.
The following is multiple choice question (with options) to answer.
What do industries use water to generate? | [
"light",
"pollution",
"electricity",
"refrigeration"
] | C | Rechargeable batteries are renewable because they can be refilled with energy. Is the energy they are refilled with always renewable?. |
SciQ | SciQ-6951 | evolution, zoology, anatomy
Title: Are the transverse septum in sharks and the diaphragm in mammals homologous structures? Are the transverse septum in sharks and the diaphragm in mammals homologous structures?
I have searched on Google Scholar and Web of Science, but haven't found substantial evidence to prove or falsify the claim. A beginning of answer here below, I hope. Please first consider that many structures are involved in the question here, the diaphragm (UBERON:0001103), the diaphragmaticus muscle (UBERON:0036071) and the septum transversum (UBERON:0004161). At Bgee (bgee.org) we aim annotating relations of similarity between anatomical structures, please have a look at our GitHub
https://github.com/BgeeDB/anatomical-similarity-annotations
We already annotated 'diaphragm' as a mammalian structure, not homologous in Amniota (please see https://raw.githubusercontent.com/BgeeDB/anatomical-similarity-annotations/master/release/similarity.tsv). In our next release, you will see the annotation for the 'diaphragmaticus muscle' which is an analog organ in Crocodylians (and Turtles) but not homologous to the mammalian diaphragm either. See here for more details about this new Uberon class:
https://github.com/obophenotype/uberon/issues/1229.
Based on the comments here above, I would say that currently we can argue that there is no evidence for a homologous relationship between the 'septum transversum' in sharks and the mammalian diaphragm. Please note that UBERON:0004161 septum transversum describes the (mammalian) embryonic structure that will give rise to the central tendon of the diaphragm, while here you are talking about a adult structure closer to a 'diaphragmaticus muscle'-like septum, as far as I understand.
But anyway thank you for your interesting question that points out a very exciting and rapidly evolving evo-devo field, as this recent paper also suggests
The following is multiple choice question (with options) to answer.
Mammals are synapsids, meaning they have a single opening in what structure? | [
"heart",
"spine",
"hip",
"skull"
] | D | Evolution of Mammals Mammals are synapsids, meaning they have a single opening in the skull. They are the only living synapsids, as earlier forms became extinct by the Jurassic period. The early non-mammalian synapsids can be divided into two groups, the pelycosaurs and the therapsids. Within the therapsids, a group called the cynodonts are thought to be the ancestors of mammals (Figure 29.36). |
SciQ | SciQ-6952 | aqueous-solution
A final point is that some dissolved species can, in fact, be solvents on their own. In this case, the definition of whether the species is aqueous or liquid is not well-defined and usually depends on the context. For example, a 1:4 mixture of $\ce{MeOH}$ and $\ce{H_2O}$ is typically written as $\ce{MeOH{(l)} + {H_2O{(l)}}}$, but a solution where a small amount of $\ce{MeOH}$ (maybe used as a reactant) would be denoted $\ce{MeOH{(aq)}}$. This has to do with the definition of the thermodynamic activities of the species and if you have questions about this, there's probably someone else on here who is a better expert than I to explain.
The following is multiple choice question (with options) to answer.
What are the properties of solutions called that depend only on the concentration of dissolved particles and not on their identity? | [
"colligative properties",
"platyhelminth properties",
"platyhelminth properties",
"platyhelminth properties"
] | A | The vapor pressure of a solution is lower than that of the pure solvent at the same temperature. This decrease in vapor pressure is one example of a colligative property . Colligative properties are properties of solutions that depend only on the concentration of dissolved particles and not on their identity. |
SciQ | SciQ-6953 | physical-chemistry, everyday-chemistry, thermodynamics
As a comparison to this example, let's check out two liquids that do mix.
3. Water and ethanol
For the water, we have basically the same situation as before -- water molecules forming good bonds to each other. The ethanol, though, has an -OH group that can form bonds to the water in the same way that the water does (though not as well). This means that ethanol that mixes with water (and vice versa) will tend to stay mixed, and given that the liquids are being mixed around just by random motions, means that you'll get one mixing with the other just as a matter of statistics.
The following is multiple choice question (with options) to answer.
Liquids that mix with each other in all proportions are said to be miscible, maning they have infinite mutual what? | [
"viscosity",
"insolubility",
"solubility",
"salinity"
] | C | Solutions of Liquids in Liquids We know that some liquids mix with each other in all proportions; in other words, they have infinite mutual solubility and are said to be miscible. Ethanol, sulfuric acid, and ethylene glycol (popular for use as antifreeze, pictured in Figure 11.14) are examples of liquids that are completely miscible with water. Two-cycle motor oil is miscible with gasoline. |
SciQ | SciQ-6954 | thermodynamics, temperature, pressure, ideal-gas
Title: With ideal gases, varying quantity of moles, and having a constant volume how do temperature and pressure behave? I'm trying to build a simulation of gases so I ended-up trying to use law of ideal gases ($PV = nRT$).
In my scenario:
volume is constant ($V=1\rm{m}^3$);
a known quantity of moles are being added to the system ($n_{added}$);
both pressure ($P$) and temperature ($T$) are unconstrained.
The following is multiple choice question (with options) to answer.
Which law relates the pressure, volume, and temperature of a gas? | [
"shifts gas law",
"directions gas law",
"newton's law",
"combines gas law"
] | D | The combined gas law relates pressure, volume, and temperature of a gas. |
SciQ | SciQ-6955 | newtonian-mechanics, energy, work
Title: Types of energy and work I am learning about energy and work, and am a beginner to this topic. Energy is defined as the ability to do work. In some cases, the ability to do work directly follows the type of energy. For instance, heat energy can be used to do work through isothermal expansion of gas, for instance.
Is there a relationship/concept between how easy it is to get a type of energy to do work? Some types of energy might make them more suitable to do work, whereas others might involve a more indirect/contrived route. Energy defined as the ability to do work; this does not mean that only work is done, it means that work can be done.
Here is an expanded definition that should help.
The energy of a system is a property of the system that is increased (decreased) by the following mechanisms:
work done on (or done by) the system from its surroundings
heat added to (or removed from) the system from its surroundings
mass transfer into (or from) the system to its surroundings.
"How easy it is to get a type of energy to do work" depends how the system interacts with the surrounding.
For example, if a system comprised of a gas has a higher pressure than its surroundings and can move a boundary (say a piston), the system can lose energy by doing work on the surroundings as the gas expands. Or if the gas is in a closed container (fixed volume) and has a higher temperature than its surroundings, the gas can lose energy by transferring heat to the surroundings. A liquid can have a decrease in its energy, with a decrease in its temperature, by evaporation (mass transfer from the liquid).
The details of energy transfer is addressed by the laws of thermodynamics (e.g., the first and second laws).
The following is multiple choice question (with options) to answer.
Heat and light are forms of what, which refers to the ability to do work? | [
"food",
"waves",
"fuel",
"energy"
] | D | Energy is the ability to do work. Heat and light are forms of energy. Energy can change form. It can also move from place to place. |
SciQ | SciQ-6956 | geophysics, earthquakes, plate-tectonics, geography
Title: Why is the Ring of Fire there? The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else?
Any help would be appreciated! This question is very similar to: Why does the "Ring of Fire" pretty much define "Pacific Rim"
The high levels of volcanoes and earthquakes are primarily due to subduction. So why is the Pacific surrounded by subduction zones?
Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it. This destruction of the ocean plate(s) occurs at subduction zones.
This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.
The following is multiple choice question (with options) to answer.
Volcano chains form as an oceanic plate moves over what? | [
"hot spot",
"Water spot",
"melt spot",
"dust spot"
] | A | A chain of volcanoes forms as an oceanic plate moves over a hot spot. This is how it happens. A volcano forms over the hotspot. Since the plate is moving, the volcano moves off of the hotspot. When the hotspot erupts again, a new volcano forms over it. This volcano is in line with the first. Over time, there is a line of volcanoes. The youngest is directly above the hot spot. The oldest is the furthest away ( Figure below ). |
SciQ | SciQ-6957 | solar-system, jupiter, gas-giants, saturn, uranus
From the second hit:
Jupiter is a giant gas planet with an outer atmosphere that is mostly
hydrogen and helium with small amounts of water droplets, ice
crystals, ammonia crystals, and other elements. Clouds of these
elements create shades of white, orange, brown and red. Saturn is also
a giant gas planet with an outer atmosphere that is mostly hydrogen
and helium. Its atmosphere has traces of ammonia, phosphine, water
vapor, and hydrocarbons giving it a yellowish-brown color. Uranus is a
gas planet which has a lot of methane gas mixed in with its mainly
hydrogen and helium atmosphere. This methane gas gives Uranus a
greenish blue color Neptune also has some methane gas in its mainly
hydrogen and helium atmosphere, giving it a bluish color
The following is multiple choice question (with options) to answer.
What type of planet is jupiter? | [
"a gas giant",
"a phantom",
"a red dwarf",
"a noble gas"
] | A | Since Jupiter is a gas giant, could a spacecraft land on its surface? The answer is no. There is no solid surface at all! Jupiter is made mostly of hydrogen, with some helium, and small amounts of other elements. The outer layers of the planet are gas. Deeper within the planet, the intense pressure condenses the gases into a liquid. Jupiter may have a small rocky core at its center. |
SciQ | SciQ-6958 | thermodynamics, energy, temperature, water
Title: How does my car antifreeze work (in thermodynamic terms)? Freezing point depression Water freezes at 0$^{\circ}$ C, ethylene glycol freezes at -12$^{\circ}$ C, but my car starts at -20$^{\circ}$ C. Mixing them together prevents my car engine's coolant from freezing down to -30$^{\circ}$ C, (at least that's what it says on the label of the can).
This question Freezing Point Depression : Enthalpy and Entropy is related, but unfortunately, it is not answered.
Salt and water freezing point is also related but not a duplicate, as far as I can tell.
The concepts behind enthalpy and entropy are both familiar to me, but their role in freezing point depression is not.
I do know that the antifreeze process is based on the prevention of ice crystals in the water, and from Wikipedia Ethylene Glycol I read that:
Ethylene glycol disrupts hydrogen bonding when dissolved in water. Pure ethylene glycol freezes at about −12 $^{\circ}$ C but when mixed with water, the mixture does not readily crystallize, and therefore the freezing point of the mixture is depressed. Specifically, a mixture of 60% ethylene glycol and 40% water freezes at −45 $^{\circ}$ C.
The following is multiple choice question (with options) to answer.
What does antifreeze do to the freezing temperature of the water in car radiators? | [
"keeps it constant",
"raises it",
"foresees it",
"lowers it"
] | D | Flickr:EvelynGiggles. Antifreeze lowers the freezing temperature of the water in car radiators . CC BY 2.0. |
SciQ | SciQ-6959 | redox, reactivity, reaction-control
Title: Oxidation Reactions/Reactivity of Manganese Metal in Air and Water I am planning on doing some reactions that lead to Manganese metal and a neutral solution containing $\ce{Mn^{2+}}$ as by-products, and I wanted to try some things out with the Manganese as well.
Since Manganese has common charges of II and III, will a relatively fine, grainy form of the metal burn (and at what temperature) in air to form a mixed "$\ce{Mn(II, II)}$" oxide, $\ce{Mn3O4}$, the way Iron does as it rusts, or is $\ce{MnO}$ more predominant?
I have the same question about whether or not $\ce{Mn3O4}$ is formed in "thermite-like" reactions such as reacting $\ce{CuO}$ with $\ce{Mn}$.
As for water, I know that Manganese metal is one of the more active metals among the transition metals, so I am also concerned with whether Aluminum can be used to reduce $\ce{Mn^{2+}}$ to the metal in boiling water without the formation of any Manganese Oxide or Hydroxide side products due to the water (especially due to the fact that reducing metals like this precipitates them out as a fine powder).
$\ce{ 2Al + 3Mn^{2+} -> 2Al^{3+} + 3Mn}$ Unlike your claim, manganese is relatively inert despite it being a little more electropositive than its neighbors in the periodic table. It is not particularly reactive to air. The surface of manganese lumps oxidize to a minor extent but when it is finely divided, it becomes pyrophoric and burns in air. It tends to form the oxide $\ce{Mn3O4}$ and the nitride $\ce{Mn3N2}$. Temperature for such reactions are reaches more than 500 °C.
$$\ce{3Mn(s) + 2O2(g) ->[\Delta] Mn3O4(s)}$$
The following is multiple choice question (with options) to answer.
What process typically occurs to metal exposed to outside elements? | [
"explosion",
"shrinkage",
"extraction",
"corrosion"
] | D | Metal exposed to the outside elements will usually corrode if not protected. The corrosion process is a series of redox reactions involving the metal of the sculpture. In some situations, the metals are deliberately left unprotected so that the surface will undergo changes that may enhance the esthetic value of the work. |
SciQ | SciQ-6960 | astrophysics, radiation, thermal-radiation, plasma-physics
Title: Is Sun brighter than what we actually see? I learned from that plasma can reflect radiations of frequency less than that of its own oscillations. If so, considering the plasma in Sun's atmosphere, it should also reflect solar radiations.
That would mean that the radiation emitted from the inner layers of the Sun would be reflected back by the outer layers. So, the only radiation coming out should be the ones generated at the outer layers, for which there is no denser layers of plasma surrounding it. And of course, the ones that have higher frequencies than the plasma in each layer would come out unscathed.
If this is true, most of the radiation generated by fusion will be trapped inside, and what we observe is only a fraction.
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer. So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties? Is Sun brighter and hotter than what we see from outside?
Note that the intensity of observable radiation coming out from stars would now mostly depend on the outermost layer.
Because the material in the star is opaque, it completely depends on the outermost layer. Of course the properties of that layer (such as its temperature) are driven by the energy coming from the interior.
So, wouldn't it be inappropriate to consider stars as Black bodies while determining their temperature and other properties?
It is appropriate for an object that has a spectrum that closely matches a blackbody spectrum. However the only property that describes is the temperature of the visible layer. It doesn't imply anything about the interior and processes that produce and distribute energy. You shouldn't read blackbody and think that means that the (invisible) interior is simple or in some way similar to the exterior.
The sun's interior is much hotter than the exterior (around 15 million Kelvin in the core, compared to the 6000 Kelvin or so at the photosphere). Because it is not visible, I would hesitate to call it "brighter". But you could consider it that way.
The following is multiple choice question (with options) to answer.
The innermost layer of the sun is known as what? | [
"photosphere",
"convective zone",
"core",
"surface"
] | C | The core is the Sun's innermost layer. The core is plasma. It has a temperature of around 15 million degrees Celsius (°C). Nuclear fusion reactions create the immense temperature. In these reactions, hydrogen atoms fuse to form helium. This releases vast amounts of energy. The energy moves toward the outer layers of the Sun. Energy from the Sun's core powers most of the solar system. |
SciQ | SciQ-6961 | 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.
Motor neurons and sensory neurons are part of what nervous system? | [
"sensory-somatic",
"autonomic",
"peripheral",
"central"
] | A | Sensory-Somatic Nervous System The sensory-somatic nervous system is made up of cranial and spinal nerves and contains both sensory and motor neurons. Sensory neurons transmit sensory information from the skin, skeletal muscle, and sensory organs to the CNS. Motor neurons transmit messages about desired movement from the CNS to the muscles to make them contract. Without its sensorysomatic nervous system, an animal would be unable to process any information about its environment (what it sees, feels, hears, and so on) and could not control motor movements. Unlike the autonomic nervous system, which has two synapses between the CNS and the target organ, sensory and motor neurons have only one synapse—one ending of the neuron is at the organ and the other directly contacts a CNS neuron. Acetylcholine is the main neurotransmitter released at these synapses. Humans have 12 cranial nerves, nerves that emerge from or enter the skull (cranium), as opposed to the spinal nerves, which emerge from the vertebral column. Each cranial nerve is accorded a name, which are detailed in Figure 35.28. Some cranial nerves transmit only sensory information. For example, the olfactory nerve transmits information about smells from the nose to the brainstem. Other cranial nerves transmit almost solely motor information. For example, the oculomotor nerve controls the opening and closing of the eyelid and some eye movements. Other cranial nerves contain a mix of sensory and motor fibers. For example, the glossopharyngeal nerve has a role in both taste (sensory) and swallowing (motor). |
SciQ | SciQ-6962 | computability, turing-machines, physics
Title: Can normal physics laws be simulated in Digital physics? Physics is defined as the study of an object {matter or energy} with its interaction with other objects:
Physics is the study of matter, energy, and the interaction between them.
On the other hand, Digital physics is based on computations and information.
Digital physics is a collection of theoretical perspectives based on the premise that the universe is, at heart, describable by information, and is therefore computable.
The following is multiple choice question (with options) to answer.
What type of science is the study of matter and energy and includes chemistry and physics? | [
"genetics",
"Earth science",
"physical science",
"biology"
] | C | Physical science is the study of matter and energy. It includes chemistry and physics. |
SciQ | SciQ-6963 | botany, color
Hypothesis 1
It should be remembered that chlorophyll is far from being the only pigment found in leaves. For example, carotenoids - which give yellow and reddish colors - are present in plant leaves. There are many carotenoids (according to Wikipedia there are over 1100 known, but that number will continue to grow). The biological roles of these carotenoids are also varied. In the course of the question, we may be interested, for example, in the photoprotective role of carotenoids. They are involved in the deactivation of reactive oxygen species (ROS). ROS can be formed during photosynthesis and can potentially be harmful to cells. Therefore, in conditions of excess solar radiation, plants can increase concentrations of carotenoids to prevent oxidative stress. It has already been pointed out to you in the comments that younger leaves look yellow - this is a common occurrence. The leaf is a very expensive organ, in the sense that the plant invests a lot of plastic substances in its development. So it makes sense that young, growing leaves get extra protection. That is, a young leaf that has not yet formed all the necessary structures (thick enough cuticle, efficient conductive system, etc.) is less efficient in terms of photosynthesis and therefore more susceptible to negative processes of photodamage. Increased concentrations of carotenoids, among other things, can reduce such risks. If you add to this the small thickness, it is understandable why young leaves often look more yellow.
Hypothesis 2
I have already said that leaves are expensive organs. They have a high protein content, which is very valuable to the plant. If a leaf is damaged or aged, there is a threat of irreversible loss of protein, which would be a great waste. Therefore, in such cases, plants trigger complex processes of removing valuable substances from the leaves. In particular, chlorophyll begins to break down, and the decomposition products are transported to the more durable parts of the plant. This is the reason why leaves change color in the fall, before defoliation. When the concentration of chlorophyll decreases, other pigments, such as carotenoids, increasingly affect leaf color. That's why damaged and old leaves often turn yellowish.
Although, I doubt that in the case of your plant, this process is often the cause for yellow leaves.
Hypothesis 3
The following is multiple choice question (with options) to answer.
When plants lose their leaves in the fall, what chemical is produced less to cause the change? | [
"carbonate",
"chlorophyll",
"pheromes",
"oxygen"
] | B | Even if you don’t live in a place where leaves turn color in the fall, no doubt you’ve seen photos of their “fall colors” (see Figure below ). The leaves of many plants turn from green to other, glorious colors during autumn each year. The change is triggered by shorter days and cooler temperatures. Leaves respond to these environmental stimuli by producing less chlorophyll . This allows other leaf pigments—such as oranges and yellows—to be seen. |
SciQ | SciQ-6964 | evolution, embryology, chromosome, polyploidy
Unfortunately, whilst the first two points are valid facts about polyploids, the third point is incorrect. A major flaw with Muller's explanation is that it only applies to animals with chromosomal ratio-based sex determination, which we have since discovered is actually relatively few animals. In 1925 there was comparatively little systematic study of life, so we really didn't know what proportion of plant or animal taxa showed polyploidy. Muller's answer doesn't explain why most animals, e.g. those with Y-dominant sex determination, exhibit relatively little polyploidy. Another line of evidence disproving Muller's answer is that, in fact, polyploidy is very common among dioecious plants (those with separate male and female plants; e.g. Westergaard, 1958), while Muller's theory predicts that prevalence in this group should be as low as in animals.
The 'complexity' answer...
Another answer with some historical clout is the one given by Daniel Standage in his answer, and has been given by various scientists over the years (e.g. Stebbins, 1950). This answer states that animals are more complex than plants, so complex that their molecular machinery is much more finely balanced and is disturbed by having multiple genome copies.
This answer has been soundly rejected (e.g. by Orr, 1990) on the basis of two key facts. Firstly, whilst polyploidy is unusual in animals, it does occur. Various animals with hermaphroditic or parthenogenetic modes of reproduction frequently show polyploidy. There are also examples of Mammalian polyploidy (e.g. Gallardo et al., 2004). In addition, polyploidy can be artificially induced in a wide range of animal species, with no deleterious effects (in fact it often causes something akin to hybrid vigour; Jackson, 1976).
The following is multiple choice question (with options) to answer.
In which kind of animals does parthenogenesis occur? | [
"tissues",
"invertebrates",
"mammals",
"species"
] | B | Note that in fragmentation, there is generally a noticeable difference in the size of the individuals, whereas in fission, two individuals of approximate size are formed. Parthenogenesis Parthenogenesis is a form of asexual reproduction where an egg develops into a complete individual without being fertilized. The resulting offspring can be either haploid or diploid, depending on the process and the species. Parthenogenesis occurs in invertebrates such as water flees, rotifers, aphids, stick insects, some ants, wasps, and bees. Bees use parthenogenesis to produce haploid males (drones) and diploid females (workers). If an egg is fertilized, a queen is produced. The queen bee controls the reproduction of the hive bees to regulate the type of bee produced. Some vertebrate animals—such as certain reptiles, amphibians, and fish—also reproduce through parthenogenesis. Although more common in plants, parthenogenesis has been observed in animal species that were segregated by sex in terrestrial or marine zoos. Two female Komodo dragons, a hammerhead shark, and a blacktop shark have produced parthenogenic young when the females have been isolated from males. |
SciQ | SciQ-6965 | embryology
Title: What is a zygote? During fertilization, the nuclear membrane of the pro-nucleus of the ovum and sperm degenerate. Is the cell is stage called a zygote?
After the dissolution, mitosis occurs and two cells are formed.Or is the cell is stage called a zygote?
I'm confused as i knew a zygote was single-celled. Conventionally, a zygote is considered to be formed the moment that a spermatozoum, penetrates the cell membrane of the ovum and yields its genetic material into the ovum. Effectually, however, there is a lag between the instant of fertilization and the fusion of the male and female pronuclei. In mammals, the duration of this lag period is ~12 hours. There are also additional actions that must be completed before the first mitosis as in most mammals, including humans, the ovum is actually in the second metaphase of meiosis at the time of fertilization.
The following is multiple choice question (with options) to answer.
What is the name of the temporary organ that begins to form from the trophoblast layer of cells shortly after implantation? | [
"embryo",
"appendix",
"uterus",
"placenta"
] | D | The placenta is a temporary organ that begins to form from the trophoblast layer of cells shortly after implantation. (For an animation showing how the placenta forms, go to link below. ) The placenta continues to develop and grow to meet the needs of the growing fetus. A fully developed placenta, like the one in Figure above , is made up of a large mass of blood vessels from both the mother and fetus. The maternal and fetal vessels are close together but separated by tiny spaces. This allows the mother’s and fetus’s blood to exchange substances across their capillary walls without the blood actually mixing. |
SciQ | SciQ-6966 | relativity
Title: Photons inside a box One of my friends told me that the definition of mass is the amount of matter. I told him that mass is not the amount of matter, because when we heat an object, the mass of the object increases.
I gave an example: Photons moving around inside a closed massless box having walls of perfectly reflecting mirrors gives mass to the box, because the definition of mass is
$\sqrt{E^2-p^2}$ .
Inside the box, when we consider the photons as a whole they don't have momentum, thus mass becomes $m=E$ when $c=1$.
But I'm really confused what happens when the box starts moving, because in that case the momentum as a whole of the photons is not zero? What will be the mass of the box then? Don't worry too much about the word "matter": the modern view afforded by GTR, quantum field theory and much more means that the word "matter" has become very vague. If you look up the "matter" Wikipedia page, this seems to agree that the word "matter" is very vague now indeed, so as a useful concept in physics, the word seems clearly to have passed its use-by date. I actually got to the age of 45 before one day I realised ashamedly that I couldn't define the word "matter" anymore, a situation I thought was disgraceful for a physicist, but a quick sweep of the web shows that there was good reason for my plight.
The following is multiple choice question (with options) to answer.
What term is used to describe anything that takes up space and has mass? | [
"opacity",
"matter",
"weight",
"size"
] | B | If you look at your hand, what do you see? Of course, you see skin, which consists of cells. But what are skin cells made of? Like all living cells, they are made of matter. In fact, all things are made of matter. Matter is anything that takes up space and has mass. Matter, in turn, is made up of chemical substances. In this lesson you will learn about the chemical substances that make up living things. |
SciQ | SciQ-6967 | sensation, olfaction
http://www.comeaddestrareuncane.com/blog/tag/cani-molecolari/
In the dog, the surface of the olfactory mucosa varies between 70 and 150 cm2 - in this tissue the number of olfactory receptors varies from 250 to 280 million - In 1962, Becker et al. showed that dogs are able to recognize substances in dilutions from 1/100 to 1/10.000.000.
- http://milano.corriere.it/milano/notizie/cronaca/12_febbraio_19/cani-olfatto-parere-esperto-1903358352720.shtml
Have you noticed how a dog sniffs the urine of a female "tasting it"? It is the same action that makes the viper when it follows the track of the mouse: it evertes the tongue and carries on it the odorous particles in the buccal cavity, and this organ has a function in the middle between the olfactory and gustatory ones. "Pointing dogs" is as pointing "the wild" taste the smell.
"Eat the scent", in the jargon, because savored, not only in terms of smell, the smell of the wild. The Jacobson's organ is then a second organ capable of perceiving odors, the first we've said is represented ciliated epithelium of the mucous membrane of the nose.
But there is a third organ called the "Rodolfo-Masera" which also serves to sense the emanations chemical (not yet known which), that way you could explain a specialization of these organs to perceive certain groups of biochemicals than others.
- http://www.laciotola.net/Cani/la-funzione-olfattiva-del-cane.html
The following is multiple choice question (with options) to answer.
What is the organ that senses sound? | [
"skin",
"eye",
"nose",
"ear"
] | D | Hearing is the ability to sense sound waves, and the ear is the organ that senses sound. Sound waves enter the auditory canal and travel to the eardrum (see Figure below ). They strike the eardrum and make it vibrate. The vibrations then travel through several other structures inside the ear and reach the cochlea. The cochlea is a coiled tube filled with liquid. The liquid moves in response to the vibrations, causing tiny hair cells lining the cochlea to bend. In response, the hair cells send nerve impulses to the auditory nerve , which carries the impulses to the brain. The brain interprets the impulses and “tells” us what we are hearing. |
SciQ | SciQ-6968 | density, buoyancy
Title: Density of a substance I have faced a question related to Archimides' principle which is all about a car sunk in water. They said calculate the average density of the car, but i really don't what does an average density mean. Any help? Since a car is made up of many different materials, which all likely have their own different densities, the density of the car is, therefore, not the same everywhere. The average density is the density such that, were the entire car to be that density, it would have the same volume and mass.
It is very easy to figure out. The total mass of the car divided by the total volume gives you an average density for the entire car.
That is:
$$\rho_{av}=\frac{M_{total}}{V_{total}}$$
The following is multiple choice question (with options) to answer.
What can be described in terms of size, density, and distribution? | [
"dimensions",
"habitats",
"populations",
"biomes"
] | C | Populations can be described in terms of size, density, and distribution. Population growth may be exponential or logistic. The age-sex structure of a population affects the rate of population growth. |
SciQ | SciQ-6969 | 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 term for the simplest form of matter that has a unique set of properties? | [
"an element",
"a neutron",
"an electron",
"an atom"
] | A | An element is the simplest form of matter that has a unique set of properties. Examples of well-known elements include oxygen, iron, and gold (see the figure below). Elements cannot be broken down into a simpler substance. Likewise, one element cannot be chemically converted into a different element. |
SciQ | SciQ-6970 | visible-light, refraction
Title: Why don't light beams refract when they hit a curved surface I saw a diagram that showed a light beam hitting a curved glass block (half circle) and nothing happened until it hit the flat surface, in which it refracted. Why doesn't it also refract when it hit the curved surface. I also tried this in real life with the same instruments and it proved to be so. So why?
Image of diagram:
https://postimg.org/image/6kukkz3it/ Refraction is proportional to the angle away from the normal (away from right angles to the surface). In this case the angle is zero (the light enters perpendicular to the surface) so there is no refraction.
The following is multiple choice question (with options) to answer.
What causes light to refract? | [
"bending",
"speeding up",
"slowing down",
"blinking"
] | C | Light slows down when it enters water from the air. This causes the wave to refract, or bend. |
SciQ | SciQ-6971 | audio, anti-aliasing-filter
Title: How do Anti-Aliasing-Filters in audio signal processing work? I am a little confused about the use of anti-aliasing filters. As on how I am confused, please consider the following task:
Consider a simple sampling rate conversion system with a conversion rate of 4/3. The system consists of two upsampling blocks, each by 2, and one downsampling block of 3.
The frequency spectrum has periodic repetitions at integer multiples of the sampling frequency. Therefore, upsampling creates additional - unwanted - spectral images. These can be cancelled by an anti-imaging filter:
The spectrum within the blue dotted rectangles should be my output Y_1. This output will be upsampled a second time, which I think results just having 4 spectrum repetitions until 2*pi.
But, how does downsampling work? I am given the following figure from my lecture notes:
So, apparently before downsampling we apply the anti-aliasing filter, which will result in the part of the spectrum within the blue-dotted shapes. Now, we increase Omega by a factor of 2, such that.. I don't know. What exactly happens here ? I think you make this needlessly complicated. Let's do a specific example: let's say we want to go from 48 kHz up by 4/3 to 64 kHz and your signal bandwidth is 20 kHz.
In the first step, you would up-sample by a factor of 4 by inserting 3 zeros between each sample. Your new sample rate is 192 kHz. Your original spectrum is preserved and you get mirror spectra centered around 48 kHz & 96 kHz.
To eliminate this you need a lowpass filter with cutoff of 20 kHz at 192 kHz sample rate and sufficient attenuation at 24 kHz.
Finally you just down sample the result by factor of three by simply throwing away every second and third sample. This works without aliasing, since the lowpass filter has already eliminated all content that would alias.
Regarding your graphs: in general I would avoid drawing anything past the Nyqusit frequency. It's just periodic repetition and doesn't add any useful information and it can get confusing.
The following is multiple choice question (with options) to answer.
Capacitors can be used to filter out low frequencies. for example, a capacitor in series with a sound reproduction system rids it of the 60 hz what? | [
"hum",
"echo",
"vibration",
"white noise"
] | A | the current. Capacitors can be used to filter out low frequencies. For example, a capacitor in series with a sound reproduction system rids it of the 60 Hz hum. |
SciQ | SciQ-6972 | eeg, terminology
Now, the brain is a lump of neurons. Different types of neurons that are there for different types of tasks. Some of them respond to electrical activity (from the nervous system) by propagating or inhibiting electrical activity. We can see this in the lab, by observing how does one single neuron behaves but to date it has been impossible to observe what EACH neuron is doing in-vivo in a functioning brain. This is the "promise" of Neuroimaging.
So, when it comes to electroencephalography, an electrical activity (of the brain) is sensed by an instrument (the EEG aparratus). Actually, in this case, a ridiculously small number of electrodes (a few tenths) is used to sense the combined functioning of a ridiculously large number of neurons (a few billions).
Because of this "imbalance" we see patterns in the electroencephalography measurements that, macroscopically, correspond to brain function. We don't really know what is happening at the neuron level, but we can observe waves of electrical activity spreading throughout the surface of the brain and we hypothesize that this is probably because of the brain's properties of segregation and specialisation (and this, go through the introduction, at least once).
In other words, certain parts of the brain are devoted to certain functions and they "connect" together to exchange information as the brain functions.
Because of this, certain "states" of cognition can be cross referenced with certain electrical patterns.
For example:
The following is multiple choice question (with options) to answer.
What is made up of nerve cells that sense stimuli and transmit signals? | [
"muscle tissues",
"nervous tissue",
"blood tissue",
"dependent tissue"
] | B | Nervous tissue is made up of nerve cells that sense stimuli and transmit signals. Nervous tissue is found in nerves, the spinal cord, and the brain. |
SciQ | SciQ-6973 | evolution, zoology
Let's say the environmental challenge for two different kinds of carnivore (let's call them Bogs and Dats) is to catch Mophers. Both Bogs and Dats initially have the same medium-to-short muzzles. Some Bog individuals figure out that they can dig Mophers out of their burrows, and some Dat individuals figure out that they can catch Mophers at night when the Mophers leave their burrows. Both strategies are successful. Some Bogs happen to have longer muzzles than their cousins, and find it turns out that longer muzzles work synergistically with the digging strategy, allowing Bogs to stick their noses into the Mopher burrows to grab escaping Mophers. The resulting fitness advantage results in an increase of the long-muzzle trait in further generations of Bogs. Note that in this scenario it is the adaptive behavioral strategy that creates selective pressure that favors a particular genetic adaptation.
Dats on the other hand, because of their nocturnal hunting strategy, benefit from improved night vision; and long muzzles don't provide any fitness advantage to Dats because Dats don't dig Mophers from their burrows. As long as Bogs and Dats don't hybridize, they will most likely end up with long and short muzzles respectively.
The Waddington effect, also called “Genetic Assimilation”, is somewhat more direct:
An environmental stress causes a proportion of a population to develop one or more abnormal traits, by interfering with embryological development.
If there is a selective pressure in the environment that favors some subset of those traits, individuals whose genetic makeup makes them more likely to develop that subset of traits, those individuals are likely to produce more descendants than other members of the population.
If being “more likely to develop” that subset of traits results from a weakening of genetically determined development controls that would otherwise prevent development of that subset of traits, then the subset of traits can eventually become the normal phenotype.
The following is multiple choice question (with options) to answer.
Some animals prepare for the long winter by going into what? | [
"hibernation",
"fermentation",
"suspended animation",
"pollination"
] | A | |
SciQ | SciQ-6974 | combustion
Title: What happens when you 'burn' ash? This popped into my my mind while watching a match burn (don't ask me what I was doing with a burning match...).
Now as I know it, 'ash' is what you call the residual, grey-black powdery material left over following the combustion of wood.
I'm under the impression that ash is largely just carbon, with little or no organic constituents present along with it (since I'm pretty sure that pure powdered carbon is black, not grey-black).
Now I heated what remained of the matchstick with, well...another matchstick and found out, unsurprisingly, that the ash underwent practically no visible change. So I scooped up some ash into a crevice in a concrete block and then blow-torched it for about 2 minutes. Same result. However, while I was heating it this time, it glowed orange, it subsided as soon as I turned off the torch.
Thinking about it, if I did heat it strong enough it should decompose completely to black colored elemental carbon. If that is the case, to what temperature should you heat it?
I don't think I've considered everything there is to consider in this situation, which is why I've adopted a tentative tone while typing out this question.
Could there be other, side-reactions/effects as well? What would they be?
Additionally if anyone happens to know; what is it that contributes to the grey color that ash normally assumes? The principal component of wood ash appears to be calcium carbonate. (Wiki entry, "wood ash".) Other components include compounds of potassium and phosphorus. If you heat the calcium carbonate strongly enough, it will decompose into CO2 and calcium oxide. Apparently, strong heating is likely to result in less carbon instead of a larger percentage. The remaining calcium oxide is pretty stable as to temperature although addition of water will readily convert it to calcium hydroxide.
Calcium carbonate is white. White mixed with the black of any carbon present would result in a grey color.
The following is multiple choice question (with options) to answer.
It may seem as though burning destroys matter, but the same amount of what, still exists after a campfire as before? | [
"energy",
"termperature",
"mass",
"concentrations"
] | C | It may seem as though burning destroys matter, but the same amount, or mass, of matter still exists after a campfire as before. Look at the sketch in Figure below . It shows that when wood burns, it combines with oxygen and changes not only to ashes but also to carbon dioxide and water vapor. The gases float off into the air, leaving behind just the ashes. Suppose you had measured the mass of the wood before it burned and the mass of the ashes after it burned. Also suppose you had been able to measure the oxygen used by the fire and the gases produced by the fire. What would you find? The total mass of matter after the fire would be the same as the total mass of matter before the fire. |
SciQ | SciQ-6975 | isotope
Title: Is it possible to find the ratio of isotopes only given the mean mass number?
Three isotopes of an element have mass numbers $(M)$, $(M+1)$ and $(M+2)$. If the mean mass number is $(M+0.5)$, then the ratio of the amounts of the three isotopes is?
Let amount of $(M)$, $(M+1)$, and $(M+2)$ be $x$, $y$ and $z$ respectively.
$$\frac{(M)x + (M + 1)y + (M + 2)z}{x + y + z} = (M + 0.5)$$
After further simplification, I got $x-y=3z$.
I don't know how to proceed further. Can someone give me a hint, or reassure me that this question can't be solved with the given data?
The answer is given as $x:y:z=4:1:1$. You have two equations and 3 unknowns, so you can't solve it with just that. Say a, b, c are the fractions (as a decimal) of each isotope...
$$ a(x) + b(x+1) + c(x+2) = (x+\frac{1}{2}) $$
$$a + b + c = 1 $$
The 4:1:1 solution works. Another that works is 3:0:1. Another is 7:4:1. There are infinitely many solutions.
The following is multiple choice question (with options) to answer.
Different isotopes of an element have different mass numbers because they have different numbers of what? | [
"protons",
"nuclei",
"neutrons",
"electrons"
] | C | An atom’s mass number is its mass in atomic mass units (amu), which is about equal to the total number of protons and neutrons in the atom. Different isotopes of an element have different mass numbers because they have different numbers of neutrons. |
SciQ | SciQ-6976 | density, buoyancy
Title: Density of a substance I have faced a question related to Archimides' principle which is all about a car sunk in water. They said calculate the average density of the car, but i really don't what does an average density mean. Any help? Since a car is made up of many different materials, which all likely have their own different densities, the density of the car is, therefore, not the same everywhere. The average density is the density such that, were the entire car to be that density, it would have the same volume and mass.
It is very easy to figure out. The total mass of the car divided by the total volume gives you an average density for the entire car.
That is:
$$\rho_{av}=\frac{M_{total}}{V_{total}}$$
The following is multiple choice question (with options) to answer.
Density is defined as the mass of an object divided by its what? | [
"volume",
"liquid",
"size",
"growth"
] | A | Density is defined as the mass of an object divided by its volume. Propose a unit of density in terms of the fundamental SI units. |
SciQ | SciQ-6977 | osmosis, prokaryotes
Title: Does osmosis take place in prokaryotic cells? As far as I know, osmosis occurs in Eukaryotic cells, and I'm wondering if it could take place in prokaryotic cells too. Osmosis works across every cell membrane along a concentration gradient as its a physico-chemical principle. Water can cross the membrane (or cell wall), while the substance dissolved in it (for example salts) can not. Because eukaryotic cells only have a cell membrane, they will burst eventually, while bacteria (and also plant cells) have a more rigid cell wall, which will mostly prevent bursting. However the influx (or outflux) of water creates a pressure which is called turgor pressure. How this works is shown below (figure from here), bacterial cells and plant cells work pretty much the same way:
The following is multiple choice question (with options) to answer.
What element is responsible for one-half of the osmotic pressure gradient that exists between the interior of cells and their surrounding environment? | [
"nitrogen",
"sodium",
"potassium",
"calcium"
] | B | Sodium Sodium is the major cation of the extracellular fluid. It is responsible for one-half of the osmotic pressure gradient that exists between the interior of cells and their surrounding environment. People eating a typical Western diet, which is very high in NaCl, routinely take in 130 to 160 mmol/day of sodium, but humans require only 1 to 2 mmol/day. This excess sodium appears to be a major factor in hypertension (high blood pressure) in some people. Excretion of sodium is accomplished primarily by the kidneys. Sodium is freely filtered through the glomerular capillaries of the kidneys, and although much of the filtered sodium is reabsorbed in the proximal convoluted tubule, some remains in the filtrate and urine, and is normally excreted. Hyponatremia is a lower-than-normal concentration of sodium, usually associated with excess water accumulation in the body, which dilutes the sodium. An absolute loss of sodium may be due to a decreased intake of the ion coupled with its continual excretion in the urine. An abnormal loss of sodium from the body can result from several conditions, including excessive sweating, vomiting, or diarrhea; the use of diuretics; excessive production of urine, which can occur in diabetes; and acidosis, either metabolic acidosis or diabetic ketoacidosis. A relative decrease in blood sodium can occur because of an imbalance of sodium in one of the body’s other fluid compartments, like IF, or from a dilution of sodium due to water retention related to edema or congestive heart failure. At the cellular level, hyponatremia results in increased entry of water into cells by osmosis, because the concentration of solutes within the cell exceeds the concentration of solutes in the now-diluted ECF. The excess water causes swelling of the cells; the swelling of red blood cells—decreasing their oxygen-carrying efficiency and making them potentially too large to fit through capillaries—along with the swelling of neurons in the brain can result in brain damage or even death. Hypernatremia is an abnormal increase of blood sodium. It can result from water loss from the blood, resulting in the hemoconcentration of all blood constituents. Hormonal imbalances involving ADH and aldosterone may also result in higher-than-normal sodium values. |
SciQ | SciQ-6978 | orbit, speed
Finally, I shall coment that all this only relates to the magnitude of the orbital velocity (speed), but not to its direction. Comets are typically on highly eccentric orbits and, when at $r$=1AU, move in quite a different direction than Earth, even if their speed is only slightly larger. So the relative speed $|\boldsymbol{v}_{\rm comet}-\boldsymbol{v}_{\rm Earth}|$ of a comet with respect to Earth can be anyting between about 10 and 70 km/s.
The following is multiple choice question (with options) to answer.
What types of orbits do comets usually have? | [
"elliptical",
"convex",
"spectral",
"vertical"
] | A | Comets are small, icy objects that orbit the Sun in very elliptical orbits. When they are close to the Sun, they form comas and tails, which glow and make the comet more visible. |
SciQ | SciQ-6979 | homework-and-exercises, kinematics
It is not uncommon, when you have a good estimation of errors, to quote a result to a couple of additional significant figures and show the error estimate to multiple figures as well. In this case, our error estimate is not that good.
I believe it would be OK to quote the number as either $1.35 \pm 0.10 m$, or $1.4 \pm 0.1$.
Now as for the question "how much longer can the other track be"? That's a poorly phrased question - but according to my calculation above (of mean plus error), the track can be as long as 1.45 m (that would be within the error estimate). It then becomes a question of probabilities - I can say "with 50% confidence" that the track is 1.35 m longer, or with lower confidence I can state a greater difference.
Because of all these uncertainties, stating "1.4 m" is acceptable - although I would argue that people (especially physicists) need to be much better in stating their experimental error - both in the question, and in the answer. Having said that, there is an implied accuracy in a number - when you give a value like $1.4$, you imply the error is "on the order of" the least significant digit, i.e. that you mean $1.4 \pm 0.1m$ . The proposed answer with many significant figures, without an error estimate, is misleading.
Finally - it is usually good to reduce these things back to a conclusion that makes physical sense. A 1000 m course is usually run as 2.5 laps on a 400m course - so we might ask whether a distance in a measured course of $1.4/2.5m ~ 0.6m$ is reasonable. Since the track includes a complete circle, having the radius of the circle off by just 10 cm would be sufficient for this kind of error. I think that when people design athletic tracks very carefully, they try to do better than that - but it's really not a huge error.
The following is multiple choice question (with options) to answer.
What describes how close an estimate is to a known standard? | [
"diversity",
"accuracy",
"frequency",
"precision"
] | B | Accuracy describes how close an estimate is to a known standard. |
SciQ | SciQ-6980 | classical-mechanics
Title: Help me find flaws on my simple machines invention I have a work to make an invention on simple machines. First of all I am sorry if my English is not very good or clear. As we all know, simple machines are used to simplify things in life and use less work (mechanical advantage). My concept is using a pulley to pull things up, but I want to use like a machine that needs to be stepped (lever type 3) to move the pulley. But I feel like there is a flaw to my invention, and feel very frustated. This is my concept visualization:
P.S: Sorry for the language usage (Image is semi-English and semi-Indonesian language)
Thank you for the help. The idea of simple machines is usually "sacrifice length to gain force". Or the opposite, but more rarely. You have incorporated a level and pulleys in your design. Let's analyze those.
The lever
The first problem is that you have made a lever that, if you step on it, the weight will go down. But, it would already go down by gravity, this is not useful. You probably want to counteract gravity and make it go up, so something like this:
The other problem is the general idea of using a level with your foot. The thing is, you can't move your foot much. This means do not really have length to sacrifice to gain force. So, to use a lever with your foot, you have to either:
Use it to lift something very light with a single motion of the foot. It's hard to find a use for this, though. Also, it means that the edge of the lever would be really long a take much space.
Use it to lift a heavy weight, but your foot won't have enough room. To gain multiple times one floor's height, you'd probably want to jump from some roof:
Now that we got the lever "solved", let's discuss the pulley (which is much easier for you to do without being unrealistic).
Note that just having a pulley somewhere doesn't provide you an advantage. You have to use something like a snatch block:
This will indeed allow you to use a long rope to raise the weight with less effort:
The following is multiple choice question (with options) to answer.
Canoe paddles, nutcracker, and hammer are examples of what type of simple machine? | [
"lever",
"lock",
"pivot",
"handle"
] | A | The canoe paddles, nutcracker, and hammer that you read about in this lesson have something in common. All three are examples of a type of simple machine called a lever. |
SciQ | SciQ-6981 | evolution, species, speciation
Title: Are there any half-evolved animals alive today? I know that there are animals that are "simpler" than other animals but are there any that are half-evolved? Are there any animals with half-evolved functions, like arms, legs, etc?
This was part of the original question, but it was incorrect.
Saying that every species on the planet is "transitional" is an unacceptable answer because it only works on the assumption that macro-evolution is true.
Saying that all the transitional animals just died off also doesn't seem quite right. If all the previous transitional animals just went extinct, then wouldn't we just have a few specialized species alive today? This wouldn't allow for the diversity we see today.
I know that there are animals that are "simpler" than other animals but are there any that are half-evolved? Why aren't there living half ape and half humans?
Oh come on. You know if Australopithecines or Homo habilis still existed you would be asking "Why aren't there living half Homo habilis and half humans"? And when the other Great Apes go extinct you'll be wondering why there are no transitional forms between humans and monkeys. The answer to that question is, humans are apes; chimpanzees and we are pretty much as close as two species can be; we could have closer forms that survived but we could also have a much bigger gap between us and our closest relatives than we currently do. In other words, any ape is a valid example of something "half-human half-ape". It's like asking for a vehicle that's half-car, half-volvo.
Are there animals that are just starting to evolve arms and legs?
You mean, modifying fins into limbs in a general movement from water-living to land-living, like the first tetrapods are thought to have done? I like mudskippers.
Saying that every species on the planet is "transitional" because there are no ultimate or final species is an unacceptable answer because it only works on the assumption that macro-evolution is true.
The following is multiple choice question (with options) to answer.
What do most species of monkeys have that no apes or humans do? | [
"tail",
"fur",
"large brain",
"five fingers"
] | A | What's the difference between monkeys and apes? The easiest way to distinguish monkeys from the other primates is to look for a tail. Most monkey species have tails, but no apes or humans do. Monkeys are much more like other mammals than apes and humans are. |
SciQ | SciQ-6982 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
What are joints in which the bones are connected by a band of connective tissue? | [
"saddle",
"cartilaginous",
"plane",
"syndesmoses"
] | D | Syndesmoses are joints in which the bones are connected by a band of connective tissue, allowing for more movement than in a suture. An example of a syndesmosis is the joint of the tibia and fibula in the ankle. The amount of movement in these types of joints is determined by the length of the connective tissue fibers. Gomphoses occur between teeth and their sockets; the term refers to the way the tooth fits into the socket like a peg (Figure 38.24). The tooth is connected to the socket by a connective tissue referred to as the periodontal ligament. |
SciQ | SciQ-6983 | materials
Title: Making Lyophilized Cake Lookalike using household ingredients I'm working on a machine learning model to identify flaws in vaccines in lyophilized cake form. To train the model, I need a number of samples that look something like this:
I have vials, but I'm having trouble making a suitable cake – I need something that will stick to itself when dried...
What I've tried so far:
Salt dissolved in water/isopropyl alcohol
Baking soda dissolved in water/isopropyl alcohol
Both of these turned back into powder (instead of caking) when dry.
Next, I'm considering using powdered detergent, adding water, then letting it dry...
How would you recommend making this using common household ingredients? You may want to consider whey. Looks like Karen Smith, Dairy Processing Technologist at the Wisconsin Center for Dairy Research, already did some of the work for you. The result depends on the specific type of whey (a high score of 4 or 5 on the caking test means the material cakes readily, forming a gummy crust):
Whey – (Scored 2-5) – whey exhibited a wide range of caking scores. How the whey is processed has a very large effect on the tendency of the resulting powder to cake as evident in this result. Clearly, two of the samples had large amounts of amorphous lactose and without the presence of significant amounts of protein the samples readily caked.
The following is multiple choice question (with options) to answer.
What are the four stages of food processing? | [
"ingestion, digestion, absorption, and elimination",
"ingestion, digestion, elimination and extinction",
"ingestion, reproduction, absorption, and elimination",
"ingestion, digestion, absorption, and reproduction"
] | A | 41.2 The main stages of food processing are ingestion, digestion, absorption, and elimination. |
SciQ | SciQ-6984 | bioinformatics
Title: STRING ID - allelic differences and splice variants STRING has protein (amino acid sequences) mapped to a single gene ID.
I have these doubts with respect to STRING ID.
I find that
1.All alleles of a single gene share the same STRING ID and
2.Especially in Eukaryotes, splice variants of the single gene(which might translate to different proteins) share the same STRING ID.
Does STRING take into account these two things like UniProt and have different IDs based on allelic differences and splice variants?If so,how? STRING does not distinguish between different products of the same gene. E.g. for human, the protein identifier you see (ENSP...) corresponds to the longest splice form for each gene (ENSG...). Therefore, STRING won't help you if you need to distinguish between splice forms.
Splice forms are merged because for most sources of evidence, there is little data for the interactions of individual splice forms.
The following is multiple choice question (with options) to answer.
What are different forms of the same gene? | [
"genomes",
"alleles",
"nuerons",
"peptides"
] | B | Homologous chromosomes form a pair, one from each parent. Homologous chromosomes are similar in size and shape, and contain the same genes, though they may have different alleles. Alleles are alternative forms of the same gene. This diagram represents two pairs of homologous chromosomes. |
SciQ | SciQ-6985 | javascript, functional-programming
Title: "Mars Rover" challenge I have written the solution of the Mars Rover problem in JavaScript, with a sort of functional approach. I would like to know how I can improve it and if there are any additional edge cases I missed in the tests.
A rover’s position and location is represented by a combination of x and y co-ordinates and a letter representing one of the four cardinal compass points. The plateau is divided up into a grid to simplify navigation. An example position might be 0, 0, N, which means the rover is in the bottom left corner and facing North.
In order to control a rover , NASA sends a simple string of letters. The possible letters are ‘L’, ‘R’ and ‘M’. ‘L’ and ‘R’ makes the rover spin 90 degrees left or right respectively, without moving from its current spot. ‘M’ means move forward one grid point, and maintain the same heading.
Test Input:
5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM
Expected Output:
1 3 N
5 1 E
Dictionary for the rovers to reference depending on the direction they are facing:
const cardinals = {
N: {
L: 'W',
R: 'E',
move: (x, y)=>{
return {x:x, y:y+1};
},
},
E: {
L: 'N',
R: 'S',
move: (x, y)=>{
return {x:x+1, y:y};
},
},
S: {
L: 'E',
R: 'W',
move: (x, y)=>{
return {x:x, y:y-1};
},
},
W: {
L: 'S',
R: 'N',
move: (x, y)=>{
return {x:x-1, y:y};
},
},
};
The following is multiple choice question (with options) to answer.
What is the wheeled robot developed by nasa to explore the surface of mars? | [
"mars rover",
"mars robot",
"mars driver",
"mars SUV"
] | A | The Mars Rover pictured here is a wheeled robot developed by NASA. Its job is to explore the surface of Mars. The rover contains a lot of complex modern technology. But how it moves by rolling on wheels is a very old invention. The wheel was probably invented many times in different cultures, beginning at least 10,000 years ago. In addition to wheeled carts and chariots, early wheels were used for water wheels, grinding wheels, and wheels for spinning pottery. Wheels really changed human life. They revolutionized transportation and made it much easier to do many different kinds of work. |
SciQ | SciQ-6986 | human-biology, reproductive-biology
Beyond Birth Control: The Overlooked Benefits of Oral Contraceptive Pills
Harder in men
It only takes one
While the saying "it only takes one sperm" is probably an exaggeration, it carries a certain truth - you really need to shut down the production of sperm or the risk of a pregnancy is too high. Both the pill and the various IUD options have set a high bar for what's considered an acceptable risk.
Side effects and effectiveness
While hormonal contraception for women already has a multitude of side effects, often unrelated to the reproductive system, this is certainly not easier in men. The most prohibiting side effect encountered so far is impotence - not much use in taking birth control to have sex without risk of pregnancy when doing so leads to no sex at all.
Progestins have been used in multiple small studies of men for suppression of spermatogenesis and testosterone production. Progestins used alone result in significant side effects such as loss of libido and erectile dysfunction.
Update on Male Hormonal Contraception: Is the Vasectomy in Jeopardy?
(Decreased libido is also a side effect in female hormonal contraception, though. The reasons why it's seen as more acceptable there are probably sociological)
That review is a good overview on what has been tried until 2010. Many solutions failed because of side effects or because they didn't work well enough.
On testosterone:
Of note, this international study revealed that 91% of Asian and 60% of Caucasian patients became azoospermic, suggesting an ethnic difference in endocrine response
Testosterone proved to be rather good in other doses and combinations, but is not that easy to handle because it requires injections and can't be taken orally.
The following is multiple choice question (with options) to answer.
What effect does taking anabolic steroids have on testosterone production? | [
"does nothing",
"eliminates it",
"increases it",
"reduces it"
] | D | Chapter 27 1 Sperm remain in the epididymis until they degenerate. 3 The fimbriae sweep the oocyte into the uterine tube. 5 The testes are located in the abdomen. 6 b 8 b 10 c 12 a 14 c 16 d 18 b 20 A single gamete must combine with a gamete from an individual of the opposite sex to produce a fertilized egg, which has a complete set of chromosomes and is the first cell of a new individual. 22 The three accessory glands make the following contributions to semen: the seminal vesicle contributes about 60 percent of the semen volume, with fluid that contains large amounts of fructose to power the movement of sperm; the prostate gland contributes substances critical to sperm maturation; and the bulbourethral glands contribute a thick fluid that lubricates the ends of the urethra and the vagina and helps to clean urine residues from the urethra. 24 Testosterone production by the body would be reduced if a male were taking anabolic steroids. This is because the hypothalamus responds to rising testosterone levels by reducing its secretion of GnRH, which would in turn reduce the anterior pituitary’s release of LH, finally reducing the manufacture of testosterone in the testes. 26 Meiosis in the man results in four viable haploid sperm, whereas meiosis in the woman results in a secondary oocyte and, upon completion following fertilization by a sperm, one viable haploid ovum with abundant cytoplasm and up to three polar bodies with little cytoplasm that are destined to die. 28 Endometrial tissue proliferating outside of the endometrium—for example, in the uterine tubes, on the ovaries, or within the pelvic cavity—could block the passage of sperm, ovulated oocytes, or a zygote, thus reducing fertility. 30 The internal reproductive structures form from one of two rudimentary duct systems in the embryo. Testosterone secretion stimulates growth of the male tract, the Wolffian duct. Secretions of sustentacular cells trigger a degradation of the female tract, the Müllerian duct. Without these stimuli, the Müllerian duct will develop and the Wolffian duct will degrade, resulting in a female embryo. |
SciQ | SciQ-6987 | biochemistry, entomology
Title: How do ants follow each other? I was observing ants in my house.They all were going in a straight line and also some of the ants were coming back through the the same line.
I took some water and rubbed the line with my finger, then the ants were not able to follow each other. Looks like they were confused.
My assumption is that they may had secreted some chemical .
Am I right ?
If yes, then which chemical is that and how it is secreted? The chemical we are talking about here is called pheromone, trail pheromone to be specific.
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individuals.1
Pheromones are of mainly 9 types (13 exactly, but 4 not so common) which are:
Aggregation pheromones
Alarm pheromones
Epideictic pheromones
Releaser pheromones
Signal pheromones
Primer pheromones
Territorial pheromones
Trail pheromones
Sex pheromones
Nasonov pheromones
Royal pheromones
Calming pheromones
Necromones2
Ants, and many other animals, use trail pheromones to mark their trail as a guide for others in their gang. Other ants, catching the signal of trail pheromone, follow the way it goes and reach their gang leader. Trail pheromones are volatile compounds, so it is not very likely that you would see ants following the exactly same path tomorrow or a week later. All ants release trail pheromones, so as long as ants are going through that path, the trail signal will keep getting stronger and will also tell lost ants "Hey, bro! We are going this way. Don't you want to join us?" See, for example, here3:
The following is multiple choice question (with options) to answer.
Living in a large colony requires good communication. ants communicate with chemicals called what? | [
"peptides",
"hormones",
"pheromones",
"alkalides"
] | C | Living in a large colony requires good communication. Ants communicate with chemicals called pheromones . For example, an ant deposits pheromones on the ground as it returns to the nest from a food source. It is marking the path so other ants can find the food. Honeybees communicate by doing a “waggle dance. ”. |
SciQ | SciQ-6988 | organic-chemistry, biochemistry, chemical-biology, carbohydrates
Glucose predominantly occurs in nature in the form of the D‐enantiomer, which is generally believed to exist in three crystalline forms: $\alpha$‐D‐glucose monohydrate (Figure 1A)(Ref.2), anhydrous $\alpha$‐D‐glucose (Figure 1B)(Ref.2), and anhydrous $\beta$‐D‐glucose (Figure 1C)(Ref.1,3). Both anhydrous $\alpha$‐D‐ and $\beta$‐D‐glucose crystals are orthorhombic while $\alpha$‐D‐glucose monohydrate crystals are monoclinic (see Fig. 1A-C). However, a fourth form, which is metastable in solution phase at $\pu{38\!-\! 50 ^{\circ}C}$ and thought to be a hydrated form of $\beta$‐D‐glucose, has been reported as well (Ref.1,4).
The crystal structure of $\beta$-D-glucose published in 1960 (Ref.5) clearly showed the exsistence of pyranose ring system. As in the inserted box in Figure 1 state that, in aqueous solutions, 99% of D‐glucose exists as a mixture of the $\alpha$- and $\beta$-forms (approximately 62% $\beta$ and 38% $\alpha$ when equilibrated at $\pu{31 ^{\circ}C}$ (Ref.1). Recent NMR study using fully $\ce{^13C}$ labelled glucose (Ref.6) clearly showed $\alpha/\beta$ ratio of $37/63$, which is almost identical to this literature value (Figure 2):
References:
The following is multiple choice question (with options) to answer.
What complex carbohydrates are the polymers of glucose? | [
"starches",
"fruits",
"fats",
"sugars"
] | A | Starches are complex carbohydrates that are polymers of glucose. Starches are used by plants to store energy. Consumers get starches by eating plants. They break down the starches to sugar for energy. |
SciQ | SciQ-6989 | human-biology, anatomy
The proportions of diagrams and cross sections of the nasal cavity all seem wildly different. Some of them are just blatantly wrong, depicting, for example, the Eustachian tubes coming from the roof of the nasal cavity instead of the sides. It has been very difficult to find good information on any of this. I am not even sure if I am referring to the region correctly. By nasal cavity, I mean everything between the back of the throat and the posterior nares, although I am aware the nasal cavity includes the region all the way up to the anterior nares as well.
This is the only picture I can find that shows the nasal septum.
This is a better diagram of the rest of the structures. The pharyngeal tonsils are the adenoids. I'm impressed to stumble upon someone who can do that with his tongue. And mainly because I can do that myself!
Looking at the images and feeling with my tongue, this rugged area you mention is definitely too close to the nose to be the adenoids.
So I googled a bit (well, more like a lot) and I found this cool webpage which details that area.
http://www.theodora.com/anatomy/the_pharynx.html
and I found this snippet of text:
Above the pharyngeal tonsil, in the middle line, an irregular
flask-shaped depression of the mucous membrane sometimes extends up as
far as the basilar process of the occipital bone; it is known as the
pharyngeal bursa.
I've found stones in my tonsils but never in my adenoids. What I've sometimes found was dried mucus adhered to it when waking up in the morning.
I believe those stones might be rests of food (which can't really get up there).
Maybe this green mucus you found was just dried mucus? Maybe a little infection on a particular day?
I hope you get the answer, since it's passed a quite long time since you asked :)
The following is multiple choice question (with options) to answer.
What is the term for the shallow space above the zygomatic arch in a skull? | [
"angular fossa",
"Medium Fossa",
"distinct fossa",
"temporal fossa"
] | D | Figure 7.5 Lateral View of Skull The lateral skull shows the large rounded brain case, zygomatic arch, and the upper and lower jaws. The zygomatic arch is formed jointly by the zygomatic process of the temporal bone and the temporal process of the zygomatic bone. The shallow space above the zygomatic arch is the temporal fossa. The space inferior to the zygomatic arch and deep to the posterior mandible is the infratemporal fossa. |
SciQ | SciQ-6990 | zoology
Title: What is right below skin? I was skinning a gopher so my cat can eat it (it was a pest and we didn't want to waste it). I thought its organs would fall out and make a mess, but that didn't happen. There was this sticky, transparent substance that surrounded its insides. What is this casing called? My dad said it was mucus but that isn't specific enough since there is mucus inside the stomach so I don't think they are the same.
I think this casing is found in all multicellular animals but I couldn't be sure. Based on your reference to organs falling out and the overall description, I presume you're thinking of the abdominal cavity primarily, so there you'd be looking at the peritoneum or possibly the serous membranes of other organs (e.g., pleura, pericardium). These are membranous (in the general sense, not as a cell membrane) connective tissues covering the organs found in the abdomen and chest.
Other things you'll find underneath skin would include layers of fat, other connective tissues, muscle.
Here's a labeled image of a mouse dissection from Friedrich, L., Schuster, M., de Celis, M. F. R., Berger, I., Bornstein, S. R., & Steenblock, C. (2021). Isolation and in vitro cultivation of adrenal cells from mice. STAR protocols, 2(4), 100999.:
You might also look for dissections of fetal pigs or cats, which are commonly used in laboratory demonstrations for students (more often cats longer ago, more often fetal pigs these days).
The following is multiple choice question (with options) to answer.
What is the inner layer of skin called? | [
"connective layer",
"the epidermis",
"hypodermis",
"the dermis"
] | D | The dermis is the inner layer of skin. It is made of tough connective tissue. The dermis is attached to the epidermis by fibers made of the protein collagen. The dermis is where most skin structures are located. Look again at Figure above . You’ll see that the dermis has blood vessels and nerve endings. The nerve endings explain why skin can sense pain, pressure, and temperature. If you cut your skin and it bleeds, the cut has penetrated the dermis and damaged a blood vessel. The cut probably hurts as well because of the nerve endings in this skin layer. |
SciQ | SciQ-6991 | species-identification, botany, ecology, trees
Title: Identifying a shrub with unusual "many shoots" growth behavior While recently hiking in the southern mountains of New Hampshire, we came across a plant, and some of them were exhibiting what we interpreted to be a disease, or least unusual growth. On some of the nodes, there were a large number of extra stalks:
On each plant, the number and locations of these things varied, and not all of them had it. And we first assumed it was some ivy, or parasite, or separate plant, but it seemed pretty clear to us that it was coming right from the same branch.
We soon saw there were dead versions of this plant, and all of them had this "extra shoot" variation:
So we reasoned that no matter what this thing was -- natural variation or some kind of disease -- it was killing the plants.
Google image search was no help. It possibly identified the plant as a "viburnum", but was unable to help with the growth.
Anyone know what plant this is, or what this growth behavior is the result of? Possibly an example of a "Witch's Broom."
Witch's Broom is a deformity in plants (typically woody species) which typically causes dense patches of stems/shoots to grow from a single point on the plant. The name comes from the broom-like appearance of the stems.1
Witch's broom may be caused by many different types of organisms, including fungi, oomycetes, insects, mistletoe, dwarf mistletoes, mites, nematodes, phytoplasmas, or viruses.2
Sources:
1. Wikipedia
2. Book of the British Countryside. Pub. London : Drive Publications, (1973). p. 519
Image1. Gardeningknowhow.com
Image2. Iowa state University
The following is multiple choice question (with options) to answer.
Many european and asiatic elms are less susceptible to dutch elm disease than which elms? | [
"rican",
"caribbean",
"african",
"american"
] | D | Accidentally introduced in the 1900s, the fungus decimated elm trees across the continent. Many European and Asiatic elms are less susceptible to Dutch elm disease than American elms. In humans, fungal infections are generally considered challenging to treat. Unlike bacteria, fungi do not respond to traditional antibiotic therapy, since they are eukaryotes. Fungal infections may prove deadly for individuals with compromised immune systems. Fungi have many commercial applications. The food industry uses yeasts in baking, brewing, and cheese and wine making. Many industrial compounds are byproducts of fungal fermentation. Fungi are the source of many commercial enzymes and antibiotics. |
SciQ | SciQ-6992 | # Heat Transfer
#### friendlyguyken
Ideally, when a thermometer is used to measure the temperature of an object, the temperature of the object itself should not change. However, if a significant amount of heat flows from the object to the thermometer, the temperature will change. A thermometer has a mass of 31 g, a specific heat capacity of 815 J/kg·°C, and a temperature of 12°C. It is immersed in 119 g of water, and the final temperature of the water and thermometer is 41.5°C. What was the temperature of the water before the insertion of the thermometer?
The answer posted by the instructor is 43 degrees C.
I am confused because I'm getting conflicting instructions from different sources, or maybe I'm just not understanding the full concept.
The instructor's way uses:
m1c1(Tf-Ti) = m2c2(Tf-Ti)
with this I got 40 degrees C.
Another source instructed to use:
m1c1(Tf-Ti) = m2c2(Ti-Tf)
with this I got 43 degrees C.
I do understand that Q=m1c1(Tf-Ti).
So, is the posted answer incorrect, or is the instructor's method incorrect, or is it just my calculation? Thanks and much appreciated! The attached image shows my work.
#### Attachments
• 264 KB Views: 7
#### oz93666
Pheeew ...Look at all those equations and numbers in your work , makes my eyes glaze over .... No need for it , just walk through the question step by step.....
The thermometer has mass 31 gm ,heat capacity 815/kg = 25.265J/C ...
Initial temp of thermometer is 12 final temp is 41.5 ..temp change is 29.5
That means the thermometer extracts 29.5 x 25.265 J = 745.3175J from the water.
thermal capacity of water 4.185 x119 = 498J/C
so how much will temp of water change if 745J is taken ???
745/ 498 = 1.5C ....gives the answer 43C
1 person
#### benit13
The following is multiple choice question (with options) to answer.
What does a thermometer measure? | [
"size",
"precipitation",
"oxygen",
"temperature"
] | D | Temperature is the quantity measured by a thermometer. Temperature is related to the average kinetic energy of atoms and molecules in a system. Absolute zero is the temperature at which there is no molecular motion. There are three main temperature scales: Celsius, Fahrenheit, and Kelvin. Temperatures on one scale can be converted to temperatures on another scale using the following equations:. |
SciQ | SciQ-6993 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
What are plant-like protists called? | [
"algae",
"spores",
"fungi",
"sponge"
] | A | Plant-like protists are called algae. They include single-celled diatoms and multicellular seaweed. |
SciQ | SciQ-6994 | home-experiment, purification
Title: Removal of water from sulfuric acid Suppose I have a dehydration reaction of methanol to produce methoxymethane:
$$\ce{2 CH3OH(l) ->[H_2SO_4] C2H6O(g) + H2O(l)}$$
Usually, people will use sulfuric acid to dehydrate the methanol. Assuming all the methanol was reacted, how do I get rid of the water in the sulfuric acid? Will simply heating the sulfuric acid be sufficient? You should be adding stoichiometric amounts of diluted acid. Then distilation to remove the methanol by destilation. Alternatively can also use molecular sieves, or add sodium sulfate to dry the methanol
The following is multiple choice question (with options) to answer.
What is a series of processes that remove unwanted substances from water called? | [
"water filtration",
"water dilution",
"water treatment",
"water cleaning"
] | C | Water treatment is a series of processes that remove unwanted substances from water. The goal of water treatment is to make the water safe to return to the natural environment or to the human water supply. Treating water for other purposes may not include all the same steps. That’s because water used in agriculture or industry may not have to be as clean as drinking water. |
SciQ | SciQ-6995 | inorganic-chemistry, terminology
Title: What are isodiaphers? We know that isodiaphers have same difference in neutrons and protons, but I encountered another definition:
Atoms which have same isotopic axis are called isodiaphers.
I don't know what it means by "isotopic axis". Please try to explain in simple words. These are basic terms of radiochemistry:
Isotopes are nuclides with a common number of protons $Z$.
Isobars are nuclides with a common number of nucleons $A$.
Isotones are nuclides with a common number of neutrons $N$.
Isodiaphers are nuclides with a common neutron excess $N-Z=A-2Z$.
Thus, in the chart of the nuclides, isodiaphers are found in diagonals from bottom left to top right. For example, the mother and daughter nuclides of alpha decay are isodiaphers.
The following is multiple choice question (with options) to answer.
Original atoms are called what type of isotopes? | [
"product",
"component",
"offspring",
"parent"
] | D | Direction is an important component of motion. |
SciQ | SciQ-6996 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
What do you call an area covered with water, or possessing very soggy soil, all or part of the year? | [
"peninsula",
"wetland",
"island",
"stream"
] | B | Some of Earth’s freshwater is found in wetlands. A wetland is an area that is covered with water, or at least has very soggy soil, during all or part of the year. Certain species of plants thrive in wetlands, and they are rich ecosystems. Freshwater wetlands are usually found at the edges of streams, rivers, ponds, or lakes. Wetlands can also be found at the edges of seas. |
SciQ | SciQ-6997 | ecology, database, biodiversity, species-distribution
Title: Database of Geographic Range of Species Is there a database of organisms which would contain their queriable geographic location?
I would need to perform a rather simple query, such as Animals of <Location>, where Location is some well defined geographic area such as Czech Republic or Europe.
So far I have found multiple lists on Wikipedia and other webpages, however they seem to be quite incomplete as their intersect is quite small. Moreover, I have found EOL (Encyclopedia of Life) collections but they appear to struggle the same way. This is to a large extent a question of how reliable the data in the database needs to be. Reliability (and spatial scale) will differ between datasets and between species groups within datasets, and it is difficult to give a general recommendation. I doubt that you will find a single database with good coverage over all taxonomic groups, even if it is in the form of country checklists. For the most reliable information, curated country checklists for specific taxonomic groups will probably be best, but these have to be searched for individually for each taxonomic group of interest.
As a starting point, you might want to look at the occurence data that can be found in gbif.org (The Global Biodiversity Facility). The data found there is certainly not complete, and it will be misleading for many species. However, for the current distribution of relatively well-known groups of species it will give you a good idea of their distribution. This has to be evaluated on a case-by-case basis though. You can access the data in gbif using external tools, for instance using R through rgbif (there is also tools for python or other languages). At the blog recology.info you can find a tutorial on how to get a species list for a particular country using rgbif (more specifically the function density_spplist).
The following is multiple choice question (with options) to answer.
In which continent are meerkats most likely to be found? | [
"Australia",
"africa",
"South America",
"North America"
] | B | Another example of cooperation is seen with meerkats. Meerkats are small mammals that live in Africa. They also live in groups and cooperate with one another. For example, young female meerkats act as babysitters. They take care of the baby meerkats while their parents are away looking for food. |
SciQ | SciQ-6998 | # A. P. French homework 1-2(a) Force exerted on satellite by Sun's radiation
## Homework Statement
The intensity of the Sun's radiation just outside the Earth's atmosphere is approximately $8 \cdot 10^4 \frac {joules}{m^2 \cdot min}$. Echo II is a spherical shell of radius $r_0 =$ 20.4m. Its skin consists of a layer of Mylar plastic ... between two layers of aluminum. ... Aluminum's reflection coefficient is .81.
Approximately what force does [the Sun's] radiation exert on the Echo II reflecting satellite balloon?
## Homework Equations
(From experiment explained earlier in the chapter)
$$c = \frac {W(1 + ρ)}{F}$$
(Solved for force)
$$F = \frac {W(1 + ρ)}{c}$$
Where W is the rate of arrival of energy, F is the rate of change of momentum (force), ρ is the reflection coefficient, and c is the speed of light in a vacuum.
## The Attempt at a Solution
This seemed like a flux problem, so
$$\iint_D{F(r(\varphi,\vartheta)) \cdot (r_\varphi \times r_\vartheta) dA}$$
Where
$$r(\varphi,\vartheta) = r_o sin \varphi cos \vartheta \textbf{i} + r_o sin \varphi sin \vartheta \textbf{j} + r_o cos \varphi \textbf{k}$$
$$F = -\frac{W(1 + ρ)}{c}\textbf{k}$$
$$r_\varphi \times r_\vartheta = r_o^2 sin^2 \varphi cos \vartheta \textbf{i} + r_o^2 sin^2 \varphi sin \vartheta \textbf{j} + r_o^2 sin \varphi cos \varphi \textbf{k}$$
so
The following is multiple choice question (with options) to answer.
What is the name of the thin layer that acts as a boundary between the stratosphere and the mesosphere? | [
"ozone layer",
"spirogyra",
"spicule",
"stratopause"
] | D | At the top of the stratosphere is a thin layer called the stratopause. It acts as a boundary between the stratosphere and the mesosphere. |
SciQ | SciQ-6999 | human-biology, metabolism, toxicology
Title: How does the human body metabolize gasoline? A Chinese man has been drinking gasoline to relieve his pain for 25 years. How does the human body metabolize gasoline? Also, what are the side-affects to gasoline? Just to add an answer to the 'how does the body process gasoline?' portion of the question, the liver and kidney would be doing most of the work of removing the stuff from the system once it was absorbed in the digestive tract.
The liver does most of the processing of toxins and their removal from the blood and would tend to do the most work in removing hydrocarbons from gasoline. It has enzymes that oxygenate toxins (adds oxygens) which make them more soluable in the blood, usually less toxic, and also removable from the body by the liver or the kidney. In the case of gasoline the compounds are likely to be just as toxic.
The kidney works by actively filtering out excess water and mostly water soluable wastes like oxygenated hydrocarbons. Kidney damage occurs when gasoline is ingested in excess. This may be due to the toxicity of the gasoline, but also due to the compounds the liver is producing.
Gasoline will tend to be fat soluable too, so it will leave the system more slowly, even after being processed by the liver (benzene and toluene in gasoline will tend to become phenols which are quite toxic and fat soluable).
http://www.ncbi.nlm.nih.gov/pubmed/3379185
The following is multiple choice question (with options) to answer.
What is the process of removing wastes and excess water from the body? | [
"ingestion",
"excretion",
"diffusion",
"depletion"
] | B | Excretion is the process of removing wastes and excess water from the body. It is one of the major ways the body maintains homeostasis. Organs of excretion make up the excretory system. They include the kidneys, large intestine, liver, skin, and lungs. |
SciQ | SciQ-7000 | Of each score from any number, of the distribution we not just use the popular mean... Gives a measure of dispersion indicates the degree to which numerical data to. It also works in percentage terms as a percentage of some starting level which looks like.. Is calculated as the square root of the highest and smallest values the difference of each observation from mean.. Another term for these statistics is measures of dispersion like range, R, of deviations... Are useful measures are useful please provide specific applications in which one measure! Each value from the mean or average determining the variation between each data point relative to mean... Are a measure of dispersion indicates the degree to which individual items in a series other is Graphical method are! Are on the scale of measurement how spread out the data score from any number R of. And minimum values on the number line less intuitive hand, relative measures of spread between... Other measures of dispersion in the past, we will discuss the standard deviation, and!
The following is multiple choice question (with options) to answer.
Which measure shows how individuals in a population are distributed, or spread throughout their area? | [
"geographical distribution",
"population distribution",
"proportional distribution",
"population phase"
] | B | Population density is an average measure. Often, individuals in a population are not spread out evenly. Instead, they may live in clumps or some other pattern. How individuals in a population are distributed, or spread throughout their area, is called population distribution. You can see different patterns of population distribution in Figure below . Different patterns characterize different species and types of environments, as you can read in the figure. |
SciQ | SciQ-7001 | organic-chemistry, biochemistry, carbohydrates
Title: Is formaldehyde a carbohydrate? Formaldehyde has the formula $\ce{CH2O}$, and the ratio of atoms in a simple carb is $\ce{1C:2H:1O}$. This fits the formula of carbohydrates. When I researched this, I found some sources saying that formaldehyde is the simplest carb, but other sources saying it is glycolaldehyde ($\ce{C2H4O2}$). Is formaldehyde a carbohydrate? According to IUPAC definition:
‘carbohydrate’ includes monosaccharides, oligosaccharides and polysaccharides as well as substances derived from monosaccharides by reduction of the carbonyl group (alditols), by oxidation of one or more terminal groups to carboxylic acids, or by replacement of one or more hydroxy group(s) by a hydrogen atom, an amino group, a thiol group or similar heteroatomic groups. It also includes derivatives of these compounds [...]
But according to Wikibooks
the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons. Natural saccharides are generally built of simple carbohydrates called monosaccharides with general formula $\ce{(CH2O)_n}$ where $n$ is three or more [...]
Because formaldehyde and glycolaldehyde (not a true sugar) has one and two carbon respectively in its structures we can exclude both as a carbohydrate.
The following is multiple choice question (with options) to answer.
What is a simple carbohydrate with the chemical formula c 6 h 12 o 6 better known as? | [
"alcohol",
"fructose",
"glucose",
"glutamate"
] | C | Glucose is a simple carbohydrate with the chemical formula C 6 H 12 O 6 . It stores chemical energy in a concentrated, stable form. In your body, glucose is the form of energy that is carried in your blood and taken up by each of your trillions of cells. Glucose is the end product of photosynthesis, and it is the nearly universal food for life. |
SciQ | SciQ-7002 | 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.
Groups of related organs form what? | [
"artificial systems",
"maturation systems",
"organ systems",
"community systems"
] | C | Animals not only have specialized cells. Most animals also have tissues and organs. In many animals, organs form organ systems, such as a nervous system. Higher levels of organization allow animals to perform many complex functions. What can animals do that most other living things cannot? Here are some examples. All of them are illustrated in Figure below . |
SciQ | SciQ-7003 | 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.
Each lymph organ has a different job in what system? | [
"immune",
"circulatory",
"nervous",
"respiratory"
] | A | Each lymph organ has a different job in the immune system. |
SciQ | SciQ-7004 | atoms, terminology
Title: What is a neutral atom? I was told that an atom's atomic number is defined as follows:
The number of electrons or protons present in a neutral atom is called atomic number. It is represented by Z.
What does neutral mean here? Why isn't it just "..present in an atom..."? Electrons and protons are charged particles. The electrons have negative charge, while protons have positive charge. A neutral atom is an atom where the charges of the electrons and the protons balance. Luckily, one electron has the same charge (with opposite sign) as a proton.
Example: Carbon has 6 protons. The neutral Carbon atom has 6 electrons. The atomic number is 6 since there are 6 protons.
The following is multiple choice question (with options) to answer.
The number of protons in an atom is called what? | [
"metallic number",
"atomic number",
"isotope",
"mass number"
] | B | The atomic number is the number of protons in an atom. This number is unique for atoms of each kind of element. For example, the atomic number of all helium atoms is 2. |
SciQ | SciQ-7005 | rocks, remote-sensing, archaeology, ground-truth
Together, #1, #2, and #3 tell us that it's probably early summer just after the river ice has broken up.
The tooth-like features in the left image are simply erosional remnants sticking out of the riverbank. They could be bedrock (not likely), ice wedges, unmelted permafrost, or simply dirt. They are on the outside of a meander, so the river is actively cutting into them, and so the river-facing faces are quite sheer and high compared to the slopes in between. The right side might be white because the conditions there had left the snow unmelted when the image was taken. And of course their shadows are longer because the river channel is at the bottom of the bluff.
If you use Google Maps or Earth to go downriver a bit (up and to the left), you will see similar features sticking out of the riverbank, but because they're at a different angle from the features in your image, the fact that they're natural is more readily apparent.
Although the terrain is much less regular on the right side of the image, again the long shadows tell the tale. There are some round lumps that may be pingoes. The shadow that looks like a man is just a coincidental jumble of shadows from the broken terrain. If you look closely at the lump that is supposed to be the "man" (which would technically be an inunnguaq) does not have any protrusions that correspond to the "arms". The "arms" are the shadow of a little cliff or shelf past the lump, which is overlapped by the lump's larger shadow.
It's similar in effect to the infamous misinterpretation of a Viking orbiter image of a natural feature on Mars as a "Face on Mars".
This is a good example of the complications of image interpretation, specifically, understanding the conditions under which the image was taken. It's also a good time to emphasize the importance of doing ground truth when interpreting images. So when you go there, let us know what you find.
The following is multiple choice question (with options) to answer.
Crevasses are found in glaciers. how do these come about? | [
"from movement",
"man made",
"rigidity",
"god"
] | A | Crevasses in a glacier are the result of movement. |
SciQ | SciQ-7006 | inorganic-chemistry, extraction
I want to use household vinegar - 6% apple vinegar if possible because it is easily available. Also, I want to use 3% pharmacy grade $\ce{H2O2}$ for the same reasons.
I have done this, kind of successfully, but I want to know what is the chemistry behind all that, and how would you calculate the amounts of reagents needed? If you want to save the iodine $\ce{I_2}$ from its solution, you may add enough $\ce{KOH}$ or $\ce{NaOH}$ in the mixture to transform all $\ce{I_2}$ into a colorless mixture of $\ce{KI}$ and $\ce{KIO_3}$. $$\ce{3I_2 + 6OH^- -> IO_3^- + 5I^- + 3H_2O}$$The remaining ethanol can then be evaporated by heating the nearly colorless solution to a temperature higher than $80$°C. When the temperature reaches $100$°C, the ethanol is totally removed from the solution : the hot solution can be cooled down to room temperature, and some acid should be added in order to destroy the excess of $\ce{NaOH}$ ou $\ce{KOH}$, and then to recover the iodine $\ce{I_2}$ according to $$\ce{IO_3^- + 5 I^- + 6 H^+ -> 3 I_2 + 3 H_2O}$$ The totality of the iodine $\ce{I_2}$ dissolved in the original tincture is recovered, without any amount of ethanol, and can be saved by filtration.
The following is multiple choice question (with options) to answer.
Combining nonpolar olive oil and polar vinegar yields what type of mixture? | [
"heterogeneous",
"omnigeneous",
"homogeneous",
"amorphous"
] | A | Another familiar example is the mixing of vinegar and olive oil. Olive oil is a nonpolar substance, while vinegar (which is mostly water and acetic acid) is polar. The result is a heterogeneous mixture that exhibits a bilayer. |
SciQ | SciQ-7007 | You collected some data, the results weren’t conclusive, so now what you want to do is collect more data until the the results are conclusive. In one sense, that’s true. By way of comparison, imagine that you had used the following strategy. Bayesian Data Analysis (3rd ed.). You are not allowed to use the data to decide when to terminate the experiment. This book is based on over a dozen years teaching a Bayesian Statistics course. Also it does incorporate some humour into the bundle like Bayesian Statistics… And as a consequence you’ve transformed the decision-making procedure into one that looks more like this: The “basic” theory of null hypothesis testing isn’t built to handle this sort of thing, not in the form I described back in Chapter 11. Most of the examples are simple, and similar to other online sources. It describes how a learner starts out with prior beliefs about the plausibility of different hypotheses, and tells you how those beliefs should be revised in the face of data. Welcome to Applied Statistics with R! All we do is change the subscript: \[ The result is significant with a sample size of $$N=50$$, so wouldn’t it be wasteful and inefficient to keep collecting data? What this table is telling you is that, after being told that I’m carrying an umbrella, you believe that there’s a 51.4% chance that today will be a rainy day, and a 48.6% chance that it won’t. Edinburgh, UK: Oliver; Boyd. I mean, it sounds like a perfectly reasonable strategy doesn’t it? You can type ?ttestBF to get more details.↩, I don’t even disagree with them: it’s not at all obvious why a Bayesian ANOVA should reproduce (say) the same set of model comparisons that the Type II testing strategy uses. 1.1 About This Book This book was originally (and currently) designed for use with STAT 420, Methods of Applied Statistics, at the University of Illinois at Urbana-Champaign. Bayes Bayes Bayes Bayes Bayes. Jeffreys, Harold. All you have to do is be honest about what you believed before you ran the study, and then report what you learned from doing it. Afterwards, I provide a brief overview of how you can do Bayesian versions of chi-square tests
The following is multiple choice question (with options) to answer.
If no conclusion is reached after an experiment, the scientist may retest what? | [
"hypothesis",
"suggestions",
"conclusion",
"materials"
] | A | The scientist must next form a conclusion. The scientist must study all of the data. What statement best explains the data? Did the experiment prove the hypothesis? Sometimes an experiment shows that a hypothesis is correct. Other times the data disproves the hypothesis. Sometimes it's not possible to tell. If there is no conclusion, the scientist may test the hypothesis again. This time he will use some different experiments. No matter what the experiment shows the scientist has learned something. Even a disproved hypothesis can lead to new questions. |
SciQ | SciQ-7008 | cardiology, fat-metabolism
Title: Can fats clog veins or capillaries? I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
I googled a bit but everything was regarding arteries.
Is it because veins have a much wider diameter than arteries that even if some fats deposit they won't clog it?
And for capillaries, they are much smaller so shouldn't they be more vulnerable to this?
In addition, I guess since one of the lymphatic vessels functions are to transport fats from capillaries in villi to bloodstream, how are they adapted to prevent deposit of fats as they carry out the transportation?
N:B I'm just an OL biology student, and also horrible at chemistry
I know that so much fats running in the bloodstream could deposit in arteries, harden forming a plaque and cause atherosclerosis. But what about veins (which are formed from same types of layers as arteries) and capillaries?
Wikipedia says this:
Veins do not develop atheromata, because they are not subjected to the same haemodynamic pressure that arteries are,[8] unless surgically moved to function as an artery, as in bypass surgery.
The cited study isn't freely available, but seems to have tested in rabbits by surgically modifying their blood flow and giving them a high fat diet.
As for capillaries, they are continuously remodeled, so while they do become clogged for a variety of reasons, once flow stops they're disassembled and new capillaries formed if the tissue becomes hypoxic.
The following is multiple choice question (with options) to answer.
What builds up in an artery and reduces blood flow? | [
"pressure",
"plaque",
"calcium deposits",
"surface tension"
] | B | Plaque buildup in an artery reduces blood flow through the vessel. |
SciQ | SciQ-7009 | bond, metal, ionic-compounds, covalent-compounds
Title: Metallic character of bonds? Why in discussions of percent character of bonds, are only ionic and covalent bondings discussed? Do bonds not have a partial metallic character, and are either metallic and ionic-covalent? One could think of the Fermi surface and conduction bands as an expression of the degree of metallic bonding, where metals such as aluminum or silver have overlapping empty and filled bands, allowing for electrical conduction, while semiconductors have a small gap between filled and conduction bands, offering more resistance.
As @Mithoron states, metallic bonding is a bulk property. Metals behave differently as nanoparticles -- for example, bulk silver is reflective, but nanometer particles of it are black, as in photographs.
The following is multiple choice question (with options) to answer.
Compounds with metals and nonmetals sharing electrons are known as what kinds of compounds? | [
"atoms",
"ions",
"eons",
"acids"
] | B | The Formation of Ionic Compounds Binary ionic compounds are composed of just two elements: a metal (which forms the cations) and a nonmetal (which forms the anions). For example, NaCl is a binary ionic compound. We can think about the formation of such compounds in terms of the periodic properties of the elements. Many metallic elements have relatively low ionization potentials and lose electrons easily. These elements lie to the left in a period or near the bottom of a group on the periodic table. Nonmetal atoms have relatively high electron affinities and thus readily gain electrons lost by metal atoms, thereby filling their valence shells. Nonmetallic elements are found in the upper-right corner of the periodic table. |
SciQ | SciQ-7010 | microbiology, bacteriology, photosynthesis
2H+ + 2e– → H2
So that the overall reaction becomes:
2H2O + hν → 2H2 + O2
(Of course, this will be at the expense of energy and reducing power for carbohydrate synthesis.)
Using Hydrogenase for the Catalysis
The enzyme, hydrogenase, can catalyse the reduction of hydrogen ions shown above. This enzyme is rare in eukaryotes and absent from higher plants. It is thought to be very ancient, and may have originally been involved in energy generation from hydrogen in early evolution. One of the roles it plays in contemporary organisms is in reoxidizing NADH generated during certain fermentations in bacteria such as the Clostridium family — hydrogen is the gas produced in gas gangrene caused by Clostridium perfringens.
Certain photosynthetic organisms — notably the microalga, Chlamydomonas reinhardtii, and the photosynthetic cyanobacteria — also contain a hydrogenase in their chloroplasts. The activity of this is generally low, but appears to be coupled to photosynthesis in certain circumstances. This is through the reduced ferredoxin produced at PSI transferring its electron to the iron or iron–nickel centre of the hydrogenase:
The following is multiple choice question (with options) to answer.
What are the only organisms that can perform photosynthesis? | [
"sponges",
"monocots",
"heterotrophs",
"autotrophs"
] | D | CHAPTER SUMMARY 5.1 Overview of Photosynthesis The process of photosynthesis transformed life on earth. By harnessing energy from the sun, photosynthesis allowed living things to access enormous amounts of energy. Because of photosynthesis, living things gained access to sufficient energy, allowing them to evolve new structures and achieve the biodiversity that is evident today. Only certain organisms, called autotrophs, can perform photosynthesis; they require the presence of chlorophyll, a specialized pigment that can absorb light and convert light energy into chemical energy. Photosynthesis uses carbon dioxide and water to assemble carbohydrate molecules (usually glucose) and releases oxygen into the air. Eukaryotic autotrophs, such as plants and algae, have organelles called chloroplasts in which photosynthesis takes place. |
SciQ | SciQ-7011 | organic-chemistry, bond, molecular-structure
Chemist in general are interested in unusual bonding situations, since they challenge our understanding of the bonding and the chemistry of such molecules itself.
One of the prominent examples is the 2-norbonyl cation, the structure of which remained a mystery for a long time since it didn't fit within the common constraint of organic chemistry. Such ions are nowadays usually referred to as non-classical ions. Their bonding is different from the more common two-electron-two-centre bonds we expect in organic (and inorganic) molecules. In a first approximation they can be described with resonance (see here: What is resonance, and are resonance structures real?), but the understanding comes with a few misconceptions. A MO description involves multi-centre bonds and typically bond orders less than one.
Another interesting example of unusual bonding are fluxional molecules like bullvalene. (See also here: What is the conformer distribution in monosubstituted fluoro bullvalene?) Similarly the bonding situation in these molecules is quite fluid, which allow them to change shape in such a way and at room temperature we obtain a single signal in the proton NMR (Addison Ault. J. Chem. Educ. 2001, 78 (7), 924-927.).
The following is multiple choice question (with options) to answer.
What is an interesting example of a molecule with two central atoms, which are both c atoms? | [
"sulfur",
"water",
"acetylene",
"chloride"
] | C | Acetylene is an interesting example of a molecule with two central atoms, which are both C atoms. Polyatomic ions are bonded together with covalent bonds. Because they are ions, however, they participate in ionic bonding with other ions. So both major types of bonding can occur at the same time. |
SciQ | SciQ-7012 | species-identification, mycology
Title: ID of a purple fungus in Virginia Could someone tell me a bit more about this fungus found growing in a nearly straight line in the lawn in a wooded area of Virginia, USA? It seems rather fragile, maybe a bit "dry" This is not a moss, but a fungus of the family Clavariaceae. Most likely this is Clavaria zollingeri, commonly known as violet coral, but there are a few resembling species. Microscopy might be needed to be entirely sure.
The species is saprotrophic, so it grows on the woody debris in your picture.
The following is multiple choice question (with options) to answer.
What is the name of the fungi that are ubiquitous in lakes and soil? | [
"sporozoans",
"zygomycota",
"eomycota",
"chytrids"
] | D | |
SciQ | SciQ-7013 | periodic-table, elements
Title: Do isotones share any similarities? A trivial research in atoms and their basic theories led me to this term: "isotones"
Nuclides sharing the same number of neutrons but different atomic numbers.
A simple request or shall I say, quest:
please indicate me to any feasible similarities existing between isotones and please, DO NOT use jargon. Chemistry is determined entirely by electron interactions. Since the number of electrons in an atom is determined by the number of protons in the nucleus, the atomic number (number of protons) is what defines the chemical behavior of a given element. This means that in terms of chemical properties, isotones would have no similarities unless they happened to be in the same group (column) of the periodic table, but that would be a coincidence and would have nothing to do with the number of neutrons.
As DavePhD and ron said, the nuclear stability could be similar, since nuclear stability has a lot to do with the total number of nucleons (neutrons + protons) as well as the relative proportion of protons to neutrons. The wikipedia article on isotones discusses stability in a little more detail.
The following is multiple choice question (with options) to answer.
All the atoms of a given element have the same number of what in their nucleus, though they may have different numbers of neutrons? | [
"compounds",
"molecules",
"protons",
"electrons"
] | C | All the atoms of a given element have the same number of protons in their nucleus, but they may have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes. Many elements have one or more isotopes that are radioactive. These isotopes are called radioisotopes . Their nuclei are unstable, so they break down, or decay, and emit radiation. |
SciQ | SciQ-7014 | thermodynamics, statistical-mechanics, voltage, biophysics
Title: Voltage homogeneity across cell membrane During respiration, individual cells produce a relatively large potential difference ($\sim 100$ mV) between the inside and outside, using energy to pump $H^+$ out of the cell to the liquid environment (a proton motive force is created). Together with proton pumps, or sources, also sinks of protons are present, channels which reuse the voltage difference for other goals.
Imagine a cell like a bag, with only very few and sparse sources and sinks of protons. At the limit, take only 1 source and 1 sink, diametrically opposed, which continuously work. Is it reasonable to assume that the voltage difference created is homogeneous in space (it has same value everywhere along the surface)? How would this depend on the size of the cell?
The following is multiple choice question (with options) to answer.
What causes a voltage to exist across the membrane in cells? | [
"insulators",
"increase in energy",
"same charge",
"difference in charges"
] | D | The active transport of ions across the cell membrane causes an electrical gradient to build up across this membrane. The number of positively charged ions outside the cell is usually greater than the number of positively charged ions in the cytosol. This results in a relatively negative charge on the inside of the membrane, and a positive charge on the outside. This difference in charges causes a voltage to exist across the membrane. Voltage is electrical potential energy that is caused by a separation of opposite charges, in this case across the membrane. The voltage across a membrane is the membrane potential . Membrane potential is very important for the conduction of electrical impulses along nerve cells. The membrane potential of a cell at rest is known as its resting potential , and is discussed below. A non-excited nerve cell is an example of a cell at rest. |
SciQ | SciQ-7015 | molecular-biology, yeast
Title: Do Yeast Insertion constructs revert? If I insert a new gene with a yeast integrating plasmid and select with a drop out culture once, can I assume that the newly integrated gene will stay in the strain without putting selective pressure on it? (i.e. can i use normal liquid culture and plates after getting the yeast with the newly integrated strain? It depends upon exactly what you have done.
The standard way of using a yeast intergrating plasmid (YIp) is for it to integrate into the genome by recombination between a piece of yeast DNA that the YIp carries and the same DNA in the genome. This is often, but not necessarily, the selectable marker. So for example a YIp carrying the URA3 gene as its only yeast DNA will integrate at the URA3 locus (probably mutant to allow selection for Ura+, so more correctly ura3).
If the YIp is linearised by cutting at a site within the URA3 marker this will direct insertion and will increase the transformation efficiency.
Once insertion has taken place, the configuration at the integration site is:
chromosome...URA3...other YIp sequences...ura3...chromosome
This is inherently unstable because a looping-out event can take place via recombination between the URA3/ura3 regions. So removing selection means that you run the risk of losing the insert. Furthermore, it is possible for looping out to occur leaving the URA3 allele behind instead of the ura3 allele. So you can lose the vector even when selection is maintained (but this will depend on the exact nature of the mutation).
More complex configurations are possible where the targetting sequence is separate from the selectable marker, and where digestion removes a whole chunk of the targetting sequence before transformation. So for example if the TRP1 gene was used for targetting a plasmid with the URA3 marker in a TRP1 ura3 strain you would get:
chromosome...TRP1 fragment A...URA3+other YIp sequences...TRP1 fragment B...chromosome
The following is multiple choice question (with options) to answer.
A synergist that makes the insertion site more stable is called a what? | [
"dominator",
"fixator",
"kilocalorie",
"lesion"
] | B | CHAPTER REVIEW 11.1 Interactions of Skeletal Muscles, Their Fascicle Arrangement, and Their Lever Systems Skeletal muscles each have an origin and an insertion. The end of the muscle that attaches to the bone being pulled is called the muscle’s insertion and the end of the muscle attached to a fixed, or stabilized, bone is called the origin. The muscle primarily responsible for a movement is called the prime mover, and muscles that assist in this action are called synergists. A synergist that makes the insertion site more stable is called a fixator. Meanwhile, a muscle with the opposite action of the prime mover is called an antagonist. Several factors contribute to the force generated by a skeletal muscle. One is the arrangement of the fascicles in the skeletal muscle. Fascicles can be parallel, circular, convergent, pennate, fusiform, or triangular. Each arrangement has its own range of motion and ability to do work. |
SciQ | SciQ-7016 | physiology, neurophysiology, respiration, breathing, pulmonology
Title: Is breathing a reflex action or is it an intrinsic process? The process of breathing is controlled by respiratory centers in the brain stem. Do these centers have an innate activity, i.e., just send out signals to breathing muscles intrinsically, and have the rate and manner in which they do so modified by various regulatory factors?
Or are they driven by imbalances (in levels of oxygen, carbon dioxide, hydrogen ions) like a reflex? Let's say that hypothetically these levels remain static in an acceptable state such that this reflex is no longer needed, would breathing stop since there's no longer a driving motive or would it continue because the respiratory centers have an intrinsic activity? While the ultimate purpose of breathing could be considered to be the maintainance of a balance of the substances you are referring to (such as blood oxygen, carbon dioxide, and hydrogen ions), the blood levels of these substances do not directly control the production of action potentials within the motor neurons that promote the contraction of the diaphragm and intercostal muscles.
The propagation of these action potentials is initiated by signals from the medullary respiratory center, specifically the neurons in the dorsal respiratory group (DRG) and the ventral respiratory group (VRG). In the VRG, a complex of neurons known pre-Bötzinger complex is responsible for generating the signals that cause the rhythmic muscle contractions involved in breathing:
The respiratory rhythm generator is located in the pre-Bötzinger complex of neurons in the upper part of the VRG. This rhythm generator appears to be composed of pacemaker cells and a complex neural network that, acting together, set the basal respiratory rate.
The following is multiple choice question (with options) to answer.
What system of the body is generally responsible for breathing? | [
"cardiac",
"excretory",
"respiratory system",
"integumentary"
] | C | The respiratory system is responsible for breathing. |
SciQ | SciQ-7017 | pressure, temperature, ideal-gas, states-of-matter
Title: Do gases have a general upper limit of density? Is there some limit for the density of gases, at which no change in condition could make it more dense without making it fluid, or solid - or something 'in between'? Yes - you can have a state where increasing the pressure would create a supercritical fluid
See Phase Diagram
The following is multiple choice question (with options) to answer.
Carbon dioxide does not rise like other gases because it has a density greater than what? | [
"air",
"water",
"light",
"gravity"
] | A | When we run a reaction to produce a gas, we expect it to rise into the air. Many students have done experiments where gases such as hydrogen are formed. The gas can be trapped in a test tube held upside-down over the reaction. Carbon dioxide, on the other hand, sinks when it is released. Carbon dioxide has a density greater that air, so it will not rise like these other gases would. |
SciQ | SciQ-7018 | electricity, electric-circuits, electric-current, voltage
The quantity you actually measure when it comes to current is the total flow - number of electrons per second passing through. If you have a 1-ohm, 5-ohm, 1-ohm resistor series, they will all have the same current going through them. This is because if they did not the current would start building up somewhere, and that would change the flow. (This actually happens, just very quickly because the wires have very low capacitance.) The way they all get the same current is they have different voltages. Most of the voltage drop for the entire circuit will be across the 5-Ohm resistor. This is like setting up pipes so that a skinny pipe goes down a steep portion of a hill while two fat pipes go down shallow portions of the hill. The total water going through each pipe per second would be the same. In this case, the water would move faster through the skinny pipe (the high-resistance portion). This is just because the total flow is the same, so if the cross-sectional area is less, the velocity is higher to compensate. This sort of picture roughly works with electrons as well. It is called the Drude model. It is the easiest to visualize, but it is not true to the quantum picture of modern physics.
Batteries do die slowly, yes. That is why flashlights, for example, grow dimmer and dimmer before turning off entirely.
To say a circuit component has a voltage is just saying that there is a certain voltage drop across that element. It is like saying that each pipe in a series of pipes running down a hill has a certain height difference, and that the height difference for the entire system of pipes is the sum of all the height differences of the individual pipes.
If two resistors are in parallel, they have the same voltage drop. This is like saying that two pipes side by side have the same height difference. The one with 1-Ohm resistance will have five times as much current going through as the one with 5-Ohm resistance.
The following is multiple choice question (with options) to answer.
What is the property that determines the amount of current flow through a particular material? | [
"pressure",
"surface tension",
"demand",
"resistance"
] | D | Resistance is the property that determines the amount of current flow through a particular material. |
SciQ | SciQ-7019 | biochemistry, metabolism
The second system, glycolysis, simply refers to the breakdown of carbohydrates (e.g. glucose) to resynthesize ATP from the energy stored in those carbohydrates. Your muscles contain a buffer of glycogen, approx. 300~ gr for the average Joe (give or take). The glycogen can be broken down to glucose-6-phosphate, which can then enter glycolysis. The glucose-6-phosphate is broken down to 2 pyruvate and yields 3 ATP netto (2 when derived from glucose, rather than glycogen, due to a first enzymatic step which requires 1 ATP). The enzymatic steps of glycolysis are controlled by ATP, AMP, ADP and other factors, factually integrating the energy status of the muscle (primarly through allosteric regulation of enzymes, especially phosphofructokinase).
The third system, the oxidative system, refers to the breakdown of carbohydrates and fatty acids, requiring oxygen to 'burn' them (citric acid cycle). The yield of this is much higher than for glycolysis, but the process is way slower.
In essence, all are regulated by the concentration of substrates and products, as well as through allosteric regulation (binding of a molecule at a different site, inhibiting or activating the enzyme, often by intermediates of the pathways themselves). Additionally, there is some long-term regulation through gene expression (e.g. up- or down-regulating expression of genes involved in these pathways), mostly by hormones.
Edit:
Well, I guess this is described in any basic biochemistry book (I'm very fund of the book 'Fundamentals of Biochemistry: Life at the Molecular Level'). If you want to see a description of these energy systems in a more exercise related context (since you were aiming at myocytes) I suggest reading Strength and Condition: Biological Principles and Practical Applications from Marco Cardinale et al., and the NSCA book Essentials of Strength and Conditioning.
The following is multiple choice question (with options) to answer.
In glycolysis, glucose is split into two molecules of pyruvate. this results in a net gain of? | [
"three atp molecules",
"two atp molecules",
"four atp molecules",
"six atp molecules"
] | B | In glycolysis, glucose is split into two molecules of pyruvate. This results in a net gain of two ATP molecules. |
SciQ | SciQ-7020 | time, acoustics
Title: Is it possible to hear the past? From this Stack Exchange Physics Post, I am certain that it is possible to view the past.
But then this interesting question came to me.
Is it possible to hear the past?
Ok, you might say, "Well, we are hearing the past, aren't we?" and go onto immense details about the speed of sound against the difference and stuff.
But what if I wanted to hear the sound of a place extremely close by days, weeks, months or even years back?
Would that be possible? Luboš' comment really answers your question, but to more specifically address your comment:
The big difference between sound and light is that sound requires a medium to travel in while light does not. In fact light travels best in a vacuum where by definition there is no medium. The reason we can see back 13.5 billion years is because the light has been travelling through an almost perfect vacuum so there's nothing to impede it.
The problem with anything travelling through a medium is that no medium is perfectly elastic and there are always energy losses due to viscous damping. This is why when you strike a bell it may ring for a while but won't ring for anything like 13.5 billion years. You could ring the bell and wait for the sound wave to travel right round the Earth. You'd hear the sound about 120,000 seconds later, so this would allow you to hear a day and a bit into the past. However, unless it was an extraordinarily loud bell the sound would have decayed to below thermal noise in that time so you wouldn't be able to hear it.
This isn't really an answer to your question, but I mention it because it's cool: cosmic events like supernovae form shock waves when they hit ares of concentrated interstellar gas, and this is arguably a form of sound. In that case you can hear sound from many years ago, though you'd need an awfully big ear!
The following is multiple choice question (with options) to answer.
What organ do we use to hear sound? | [
"the ear",
"antennae",
"eye",
"amplifier"
] | A | The organ that we use to hear sound is the ear. Almost all the structures in the ear are needed for this purpose. Together, they gather and amplify sound waves and change their energy to electrical signals. The electrical signals travel to the brain, which interprets them as sound. |
SciQ | SciQ-7021 | inorganic-chemistry, alloy
Title: If alloys are homogeneous mixtures, why can't we separate their components? An alloy is a material composed of two or more metals or a metal and a nonmetal. And, they are usually formed by heating the elements to their melting points, and then cooling them, so that the components mix. Now, why doesn't this works backwards i.e. if we heat the alloy again to melting point of their constituents, and they should separate? Once the alloy has been formed the atoms from the different metals will have shared there electrons with each other and come to an equilibrium. In this state the metal atoms have formed a complex structure which has a different reactivity or properties than each individual metal did in its original form .
The following is multiple choice question (with options) to answer.
Mixture of metals is called what? | [
"alloy",
"amalgm",
"compound",
"fusion"
] | A | Metals such as iron are useful for many purposes because of their unique properties. For example, they can conduct electricity and bend without breaking. However, pure metals may be less useful than mixtures of metals with other elements. For example, adding a little carbon to iron makes it much stronger. This mixture is called steel. Steel is so strong that it can hold up huge bridges, like the one pictured above. Steel is also used to make skyscrapers, cargo ships, cars, and trains. Steel is an example of an alloy. |
SciQ | SciQ-7022 | thermodynamics, fluid-dynamics, temperature, flow
Title: How is melting time affected by flow rate and temperature of surroundings? Suppose you have a solid sphere of m, where m is an element with freezing point of 0 degrees Celsius.
In one scenario, you place your sphere in a (“static”) 25 degree Celsius environment and measure time, t, until melting. The sphere is fixed and cannot be displaced.
In the other, you place your sphere in environment with temperature, T, and with constant flow rate, v. Again, you measure time, t, until melting.
What is the equation that would relate the two scenarios? In other words, at what temperature and flow rate would time required for melting in the second scenario equal time required in the first? The answer to this is very subtle, and is the core subject of interest in convective heat transfer. In either case, you’ll find that most engineers would model either scenario using Newton’s law of cooling:
$$Q = hA(T-T_{\infty})$$
where $Q$ is the heat transfer rate, $A$ is the surface area of the object in contact with its surroundings, $T$ is the temperature of the object and $T_{\infty}$ is the (approximate) temperature of the surroundings. $h$ is a sort of catchall term called the “heat transfer coefficient”, which is affected by all sorts of things—in particular, by flow in the surroundings of the embedded object. Most engineers find this coefficient through empirical studies.
That being said, flow in general increases the amount of heat transfer, and so an object embedded in surroundings at a different temperature & a uniform flow will heat up/cool down to the surrounding temperature faster than without the flow.
In the case without flow, temperature gradients will actually cause flow themselves by changing the density of the fluid near the object with a different temperature, so there will still be some minor convective heat transfer—this is usually called natural convection.
The following is multiple choice question (with options) to answer.
The rate the magma cools determines what property of the rock? | [
"color",
"texture",
"location",
"size"
] | B | The rate the magma cools determines the texture of the rock. |
SciQ | SciQ-7023 | geophysics, seismology, core
Title: Why does seismic activity shed light on the inner core rigidity? Reading Introduction to Geology (MIT 2005) and Wikipedia's article on Earth's inner core, it is specified that:
Earth was discovered to have a solid inner core distinct from its liquid outer
core in 1936, by the seismologist Inge Lehmann, who deduced its presence from observations of earthquake-generated seismic waves that reflect off the boundary of the inner core and can be detected by sensitive seismographs on the Earth's surface.
Why does seismic activity would result in the conclusion that the inner core is rigid? What is the link between seismism and inner core? The question that Azzie Rogers linked to: How can we determine the size and composition of Earth's inner core?
Does answer the theory part of the question, but I will extrapolate a little more to answer the question.
The question becomes, what kind of waves travel through what? Both shear and compressional seismic waves can travel through solids, but as it turns out, you cannot shear a liquid. As you look at teleseismic raypaths (waves traveling far from the source) you can see that the wave must travel deep into the earth and then back up again. The wave forms, and directions of these wavepaths will be altered by the different compositions of Earth's layers as it travels through: a wave just traveling through the mantle will have both its shear and compressional component. A wave traveling through the mantle and outer core will lose its original shear component, and either develop a new one as it leaves the core (but distinct from the wave that travels through the mantle only) or not have one at all. And finally, a wave that travels through the mantle, outer core and inner core will have distinct wave patters as well. Its by this comparison of waveforms that we realize that the earth not only has different compositional layers, but phase boundaries as well. I am not sure seismology alone would lead to a solid inner core, but there is abundant evidence supporting that fact. When you combine Seismology, rare bits of geochemistry, the calculation of Earth's gravity , and perhaps the most important part, the magnetic dynamo generating our magnetic field, we see a fairly clear ( albeit incomplete) story.
The following is multiple choice question (with options) to answer.
Conduction from the core has what effect on the lower mantle? | [
"it cools it",
"it makes it rotate",
"it vibrates it",
"it heats it"
] | D | Conduction from the core heats the lower mantle. |
SciQ | SciQ-7024 | waves, energy-conservation, acoustics
Title: The sound energy when two or more objects collide When two objects collide in an inelastic collision, some kinetic energy is converted to sound energy and heat. How do I determine how much of the kinetic energy is converted to sound energy? Provided that I'm doing an experiment where I take the readings as seen in this question's answer.
I have tried to use the law of conservation of energy to do this:
$KE_{1i} + KE_{2i} = KE_{1f} + KE_{2f} + Sound Energy + Heat$
Since there is heat generated here, I cannot just compare the initial and final values of the kinetic energies. So, after reading this question and the answers I can now have an idea what the formula of the sound energy might be like.
$E\ \alpha\ \omega^2A^2$ where $ \omega = 2\pi f$
thus I can say $E\ \alpha\ 4 \pi^2 f^2 A^2$ ?
One problem is that the formula I found here is a proportional formula not a direct formula that is using an '=' sign so there might be some more constants added to the relationship.
I have read somewhere else that I am supposed to use sound energy density instead of sound energy, but I'm not sure if sound energy density could represent the whole energy conversion from kinetic to sound.
In addition, the reason I want to find the energy using frequency and amplitude as variables is that I want to see quantitatively the effect of increasing the speed of the objects to the amplitude of the sound produced. I know that every material has its own natural frequency on collision as seen from the coin dropping experiment.
So, what is the 'proper' way of finding the relationship between the amplitude and the speed of the objects (kinetic energy I suppose)? How much sound colliding objects make depends entirely on the objects and the medium they are in. In the vacuum of space collisions don't make a sound, at all. In Earth's atmosphere the total energy of sound released by collisions that are caused by solid objects is very small compared to the energy of the objects. This is because of the large difference in density between solids and the atmosphere.
The following is multiple choice question (with options) to answer.
What is the measure of the amount of energy found in sound waves? | [
"decibels",
"frequency",
"intensity",
"density"
] | C | A friend whispers to you in class in a voice so soft that you have to lean very close to hear what he’s saying. Later that day, your friend shouts to you across the football field. Now his voice is loud enough for you to hear him clearly even though he’s many meters away. Obviously, sounds can vary in loudness. Loudness refers to how loud or soft a sound seems to a listener. The loudness of sound is determined, in turn, by the intensity of sound. Intensity is a measure of the amount of energy in sound waves. The unit of intensity is the decibel (dB) . |
SciQ | SciQ-7025 | geology, crust, geobiology
Title: Does crustal thickness have anything to do with how life existed and sustained on Earth? The original question that was put on hold "If the crust were the thickest layer of Earth, what effect would its thickness have on organisms?" was actually one of those 'counterfactual question' found on my science book, and it was really just a 'reflect upon' question. And it's actually a hard one for me to answer since it's 'what if?'s. So by revising, it would still confuse some poeple, but I guess it's already specific on its own. But I still find it hard.
Follow up question:
And what if it ever was thicker than the mantle or the rest of Earth's layers, can the planet still sustain biological life? If the crust were the thickest layer or Earth, several things would happen:
It wouldn't be a "crust" any more, by definition. Because this is what a "crust" is: a thin layer on the exterior of something. However, if we assume that the mechanical properties of the crust (being cold and brittle etc) would extend deeper in the Earth, the following applies.
No mantle convection, or at least mantle convection weak enough to probably not affect the surface. Therefore, no volcanoes, no mountain building, no subduction, no recycling of volatile elements, no sub-seafloor hydrothermal vents.
If it's cold enough, the core probably solidified and there is no magnetic field.
A good example would be Mars. A planet hypothesised to have tectonic activity in the past, but not any more. The crust of Mars isn't the thickest layer (again - think of definitions), but it is thicker in absolute and relative terms when compared to Earth. I will leave the implications of "Marsifying" Earth on organisms for you to figure out.
The following is multiple choice question (with options) to answer.
What theory explains most of the features of earth’s surface? | [
"flat earth theory",
"plate tectonics",
"string theory",
"Big Bang theory"
] | B | The theory of plate tectonics explains most of the features of Earth’s surface. Plate tectonics helps us to understand where and why mountains form. Using the theory, we know where new ocean floor will be created and where it will be destroyed. We know why earthquakes and volcanic eruptions happen where they do. We even can search for mineral resources using information about past plate motions. Plate tectonics is the key that unlocks many of the mysteries of our amazing planet. |
SciQ | SciQ-7026 | optics, refraction, lenses, vision
Title: Refractive screen for myopia Is it possible to create a screen for a computer monitor to allow a Myopic person to see the screen without glasses? Myopia shortens the maximum focus length of an eye, i.e., the converging action of a myopic eye is too strong and, as a result, the image of a distant object is formed in front of the retina - not on the retina.
Nearsighted vision is corrected by placing a corrective concave lens in front of the eye - its diverging action compensating the excessive converging action of the eye. We can also say that, by its diverging action, the concave lens brings distant objects closer to the eye - to some short distance from which a myopic eye can focus them properly.
The stronger the myopia, the stronger the required concave lens action, the shorter that "clear vision" distance.
For this paradigm to work, the corrective lens has to be located closer to the eye than the clear vision distance and a distant object, which requires correction, has to be located further from the eye than the clear vision distance.
Obviously, under these conditions, the monitor and its corrective lens would have to be separated in space, which means that the corrective lens cannot be built into the screen.
Of course, we could have a giant magnifying glass built into the screen, like it was done in early TV's with tiny screens. This would magnify the image and make it easier to make out the details, but the image would still be out of focus.
The following is multiple choice question (with options) to answer.
What part of a person with myopia is longer than normal? | [
"arm",
"leg",
"eye",
"neck"
] | C | The eye of a person with myopia is longer than normal. As a result, images are focused in front of the retina ( top left ). A concave lens is used to correct myopia to help focus images on the retina ( top right ). Farsightedness, or hyperopia, occurs when objects are focused in back of the retina ( bottom left ). It is corrected with a convex lens ( bottom right ). |
SciQ | SciQ-7027 | physical-chemistry, electrochemistry, electrolysis
Title: What happens in an electrolytic cell when the cations are different from the metal of the anode? Suppose we have an electrolytic cell with copper(II) sulphate solution as the electrolyte, and lead metal as the electrodes.
Will lead ions be discharged from the anode into the solution? What will be left in the electrolyte after we allow this experiment to run for a while?
My question stems from the fact that during electroplating, either carbon (which is always taken to be inert) or copper is always used but no one ever discusses what happens if the electrode is made of a different metal from the cation. Will the electrodes be active in such a scenario? As with so many questions in chemistry, the answer to "What will happen if we do x?" is going to be "It depends." unless x is very precisely defined.
While an electroplating setup that contains two electrodes and a solution may seem conceptually simple, there are several intertwined things to consider:
The composition of the electrodes
The composition of the solution (and solvent)
What voltage is applied to the cell
The following is multiple choice question (with options) to answer.
The anodes in each cell of a rechargeable battery are plates or grids of lead containing spongy lead metal, while the cathodes are similar grids containing powdered what? | [
"coal",
"lead dioxide",
"carbon dioxide",
"straight dioxide"
] | B | The anodes in each cell of a rechargeable battery are plates or grids of lead containing spongy lead metal, while the cathodes are similar grids containing powdered lead dioxide (PbO2). The electrolyte is an aqueous solution of sulfuric acid. The value of E° for such a cell is about 2 V. Connecting three such cells in series produces a 6 V battery, whereas a typical 12 V car battery contains six cells in series. When treated properly, this type of high-capacity battery can be discharged and recharged many times over. As the cell is discharged, a powder of PbSO4 forms on the electrodes. Moreover, sulfuric acid is consumed and water is produced, decreasing the density of the electrolyte and providing a convenient way of monitoring the status of a battery by simply measuring the density of the electrolyte. |
SciQ | SciQ-7028 | algorithm-analysis, performance
In short: there is no single scientifically accepted method. Instead, think of science as (a) being precise about what claims you are making, and then (b) providing appropriate evidence to support those claims. What constitutes "appropriate evidence" will depend upon your specific situation. You can often look to other publications in your field to see what evaluation method they used, as initially guidance, but ultimately this is a matter of critical thinking: evaluating evidence in a logical, careful, thoughtful manner.
The following is multiple choice question (with options) to answer.
In science, what is supported by much evidence, widely accepted by credible scientists, and unlikely to be disproved? | [
"hypothesis",
"concept",
"theory",
"law"
] | C | The three theories below are essential in Earth science. Each accounts for an enormous amount of data. Each is supported by many lines of evidence. All can be used to make predications. As new evidence arises, any of these theories may need to be altered. But none of these three are likely ever to be disproved. They are accepted by nearly all of the credible scientists in their fields. |
SciQ | SciQ-7029 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
Life on earth is carbon-based. organisms need not only energy but also carbon ________ for building bodies? | [
"crystals",
"monoxide",
"atoms",
"ions"
] | C | Life on Earth is carbon-based. Organisms need not only energy but also carbon atoms for building bodies. For nearly all life, the ultimate source of carbon is carbon dioxide (CO 2 ), an inorganic molecule. CO 2 makes up less than 1% of the Earth’s atmosphere. |
SciQ | SciQ-7030 | plate-tectonics, mountains, orogeny
Just doing some quick googling, it sounds like Arizona also has both volcanic feature and eroded remnants of volcanic features. These kinds of mountains/hills are formed via a different method again, and their heights are controlled by their own method of formation. Volcanoes can vary a lot in height. They can be very small, like the volcanoes in south-east Australia where I live, or very large, like the volcanoes in the Andes mountain range, or they can be large, but broad and flat, like Hawai'i.
Erosion can carve out softer rock and leave behind more resistant stuff, and this is how some smaller hills/mountains are formed (like Uluru in central Australia). I found this online which might lead you in some interesting directions: Geologic History of Arizona By Jan C. Rasmussen
The following is multiple choice question (with options) to answer.
A crater can usually be found on the top of what kind of volcanoes? | [
"Compound",
"composite",
"Shield",
"Dome"
] | B | Composite volcanoes usually have craters on the top. Why are the craters sometimes “U” or horseshoe-shaped?. |
SciQ | SciQ-7031 | metabolism, human-anatomy, pharmacology, liver
Title: Circulation through the liver in light of drug metabolism I have a lingering question which stems from an answer that I gave to What hydrolyses aspirin within the digestive tract and blood stream?
When a drug or any other substance is absorbed into the bloodstream in the stomach or small intestine, it ultimately passes through the hepatic portal vein and into the liver sinusoids, where it is processed by hepatocytes and introduced into the general circulation via the vena cava. In terms of metabolism, this is what causes a "first-pass" effect for drugs that are ingested.
For drugs that are delivered either by intravenous, intramuscular, or sub-lingually (as in the other Biology.SE question), this first-pass effect is avoided, and the drug is introduced into the general circulation without being metabolized by the liver first.
Even though the first pass is avoided, the blood in the body still makes its way back through the liver eventually via the hepatic artery, which is a branch off of the celiac artery.
The issue I still have is, does the incoming blood from the hepatic artery merge with the blood from the hepatic portal vein? If not, does the blood from the hepatic artery still interact with the hepatocytes in some way? (it makes sense that it does, and I have also read that one of the main functions of the hepatic artery was to deliver blood supply for the liver's metabolic needs) If this is not the case, where in the body would these drugs that were introduced via IV, etc., be metabolized? Yes, the blood from the hepatic artery (proper) and the portal vein mix in the sinusoids of the liver. The hepatic vein supplies about 75% of the blood to the liver, and the hepatic artery the remaining 25%. Because the portal vein provides such a large part of the blood supply to the liver, then any disease that causes the blood to build up can cause portal hypertension.
The hepatic artery carries oxygen-rich blood from the heart. The portal vein is part of the portal system and connects the capillary beds of the gastrointestinal tract to those of the liver. Because of the larger volume through the portal vein, I think that each vessel carries about half the oxygen supply to the liver.
The following is multiple choice question (with options) to answer.
Portal veins carry blood between what? | [
"chambers of the heart",
"arteries",
"digestive organs",
"pairs of capillary beds"
] | D | |
SciQ | SciQ-7032 | ngs, scrnaseq, seurat, single-cell, 10x
Title: Does the number of RNA reads per cell obtained from the 10X scRNA experiment depend on amount of mRNA in given cell? As we know, the amount of RNA reads per cell obtained from 10X scRNA experiment vary between cells. I wonder if this is effect of technical issues or does the number of RNA reads per cell obtained from the 10X scRNA experiment depend on the amount of mRNA in that cell? For the latter to be the case, we would have to read almost all the mRNA fragments in a cell, which I don't think is likely.
Thank you for your replies in advance! I am inclined to agree with you that the reads-per-cell is dependent on the cell type and cell cycle state. In the datasets I have analyzed, I observed that immune cells tend to have far fewer reads than fibroblasts, which have fewer reads than larger epithelial cell types.
EDIT: I have also observed that macrophage populations generally have more RNA than lymphocytes. Granulocytes have even less if you even capture them in your sample.
The following is multiple choice question (with options) to answer.
Viruses depend on what type of cells? | [
"blood cells",
"host cells",
"anchor cells",
"immune system cells"
] | B | Briefly describe how viruses depend on host cells. |
SciQ | SciQ-7033 | everyday-chemistry, silver, taste
$\ce{3 Ag2S(s) + 2 Al(s) -> 6 Ag(s) + Al2S3(s)}$
But a more common approach used by many commercial products is to dissolve off the tarnish, usually in sodium thiosulfate or thiourea. This means you end up with slightly less silver on your item, but is otherwise pretty effective and very mild (it's commonly used for museum pieces).
The following is multiple choice question (with options) to answer.
Silver and ordinary table salt are two examples of chemical what? | [
"impurities",
"substances",
"organism",
"microbes"
] | B | Silver and ordinary table salt are two examples of chemical substances . A substance is matter that has a uniform and definite composition. All samples of substances, sometimes called pure substances, have identical properties. When chemists run a chemical reaction, they want to use pure materials so they know exactly what they are dealing with. They know that the reaction involves a specific substance, so they expect the same reaction to give the same results each time it is run. |
SciQ | SciQ-7034 | taxonomy, phylogenetics
Title: Usage of the taxonomic classification "Pinnipedia" According to ITIS the classification Pinnipedia is invalid, and it is proposed to rather use Caniformia. The later group however includes a range of terrestrial animals as opposed to the pinnipeds (the seals), which only include marine mammals.
Is the term Pinnipedia nevertheless still accepted and used in scientific media? Is there any debate whether to use one and not the other? The Comments section of that page has the explanation:
Wilson & Reeder (eds., 1993) note that "the pinnipeds (otariids,
odobenids, and phocids) are included within the suborder Caniformia;
placing them in a separate Order would make the Carnivora
paraphyletic." This arrangement continues to be followed in Wilson &
Reeder (eds., 2005)
If both Carnivora (Bowdich, 1821) and Pinnipedia (Illiger, 1811) are orders in the traditional Linnean taxonomic sense, then one cannot be nested within the other. If this were to happen, then Carnivora would be paraphyletic because it would exclude some of its members. The same argument is made when discussion birds as dinosaurs (you can't talk about Dinosauria that doesn't include Aves).
The problem arises when phylogenetic systematics (clade names) meets traditional Linnean systematics (orders, suborders, etc.). Phylogenetic systematics does not distinguish these higher taxonomic groups. Clades are just nested groups of monophyletic taxa.
So then to answer your last question, Pinnipedia does appear to be in common usage (Google Scholar reports several hundred citations in the past few years). The key is to distinguish Pinnipedia as a traditional Linnean order (not valid) and Pinnipedia as a monophyletic clade that includes seals, walrus, and sea lions (perfectly fine). Seals, walrus, and sea lions are all more closely related to each other than to other Carnivora, so they are monophyletic, and the name for that grouping is Pinnipedia.
Here's the Tree of Life page that has all the clade names.
The following is multiple choice question (with options) to answer.
What do we call the system of classification consisting of a hierarchy of groupings called taxa? | [
"linnaean system",
"linchpin system",
"lamarckian system",
"crocodilian system"
] | A | The Linnaean system of classification consists of a hierarchy of groupings, called taxa (singular, taxon). Taxa range from the kingdom to the species (see Figure below ). The kingdom is the largest and most inclusive grouping. It consists of organisms that share just a few basic similarities. Examples are the plant and animal kingdoms. The species is the smallest and most exclusive grouping. It consists of organisms that are similar enough to produce fertile offspring together. Closely related species are grouped together in a genus. |
SciQ | SciQ-7035 | cancer, mutations
Here is another great paper that specifically addresses your question, linking increased cell division with the accumulation of both significant and insignificant mutations, which over time, lead to an accumulation of mutations needed for cancer to develop.
The following is multiple choice question (with options) to answer.
Which disease causes cells to divide out of control | [
"cancer",
"arthritis",
"autoimmune diseases",
"mutation"
] | A | Cancer is a disease that causes cells to divide out of control. Normally, the body has systems that prevent cells from dividing out of control. But in the case of cancer, these systems fail. Cancer is usually caused by mutations. Mutations are random errors in genes. Mutations that lead to cancer usually happen to genes that control the cell cycle. Because of the mutations, abnormal cells divide uncontrollably. This often leads to the development of a tumor. A tumor is a mass of abnormal tissue. As a tumor grows, it may harm normal tissues around it. Anything that can cause cancer is called a carcinogen . Carcinogens may be pathogens, chemicals, or radiation. |
SciQ | SciQ-7036 | cell-biology, proteins, mitosis
Title: Purpose of intensive protein synthesis in G1 phase of mitosis What is the purpose of intensive protein synthesis in G1 phase of mitosis, and what purposes do these synthesized proteins serve? Why are lipids and carbohydrates not synthesized intensively as well? The G1 phase of eukaryotic cell cycle is part of interphase, which is when the cell is replicating its DNA ready for division. To understand the need for intense protein synthesis, we first need to understand how DNA is organised during mitosis.
Before DNA is condensed into chromosomes ready for nuclear division it is in the form of chromatin, a long fiber-like structure inside the nucleus. In order to condense into chromosomes, this chromatin must undergo a process of coiling and folding in order to create the chromosome 'X' structure we are familiar with.
A major part of this DNA 'miniaturization' is the folding of the double helix around proteins called Histones - this creates new structures called nucleosomes.
In order to fully condense the roughly 3 meters of DNA in the average human cell down to a singular chromosome, millions upon millions of these Histone proteins are required.
And that answers your question; intense protein synthesis during the G1 phase is required in order to produce the extremely large amount of Histone proteins that are needed for packaging DNA into chromosomes ready for cellular division.
As for carbohydrates, these are constantly being processed by the body in order for the production of ATP for use as energy. The use of said energy for mitosis is a just another constantly required use of ATP within the body. Therefore there isn't any noticeable increase in carbohydrate processing/production, as it is happening regardless of the cell's stage in its cycle.
-See the image below (from shmoop.com) that explains the process of getting DNA into a chromosome.
The following is multiple choice question (with options) to answer.
Animal cells grow mainly by synthesizing protein-rich cytoplasm, a process that is described as expensive in what way? | [
"time spent",
"calorically",
"synthetically",
"metabolically"
] | D | |
SciQ | SciQ-7037 | cell-biology, organelle
Title: Univocal identifying of a plant cell We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts in order to justify my statement.
Now in the exercise, we first had to identify the parts of a cell (which was shown in form of an image) and then in part b) reason whether it was an animal or plant cell.
I had identified a chloroplast and a vacuole and stated that the only cell with this organelles was the plant cell. My teacher answered that I had missed the fact, that the cell had also a cell wall (which is indeed a difference between plant and animal cells).
My question is
Is the fact that the cell had a cell wall necessary in my argumentation, i.e. are there other cells having chloroplasts and a vacuole without being a plant cell?
Could you provide a source which supports, or doesn't support my statement so that I can show it to my teacher?
Thanks in advance Your teacher is right, chloroplasts and vacuoles are not sufficient to define a plant cell.
Amoeba have both chloroplasts (McFadden et al, PNAS, 1994) and vacuoles (Day, J. Morphology, 1927) but they are not plants - and they do not have a cell wall.
Sea slugs eat algae and can "steal" their plastids and keep them working for weeks/months, effectively becoming photosynthetic animals for a while. This is called kleptoplastidy (Pillet, Mob. Genet. Elements, 2013).
The following is multiple choice question (with options) to answer.
Where is the cell wall located? | [
"in cell membrane",
"in the chloroplast",
"outside cell membrane",
"in the mitochondria"
] | C | The cell wall is located outside the cell membrane. It consists mainly of cellulose and may also contain lignin, which makes it more rigid. The cell wall shapes, supports, and protects the cell. It prevents the cell from absorbing too much water and bursting. It also keeps large, damaging molecules out of the cell. |
SciQ | SciQ-7038 | zoology, entomology
Title: How do insects know what is edible? What is the current scientific consensus on how insects innately know what is food and not food? If they are introduced to new food sources do they experiment with eating the new food? Could you teach a preying mantis to eat beef? Insect feeding behaviour is generally triggered by one or more conditions which may include colour, shape, chemical traces or temperature.
Insects generally locate food based on some combination of olfactory, thermal and visual queues (colour and shape). If their minimum criteria are met to specified tolerance, they will attempt to feed on whatever is nearby using their usual feeding method.
When these conditions appear on the 'wrong' target, it attracts insects and triggers feeding attempts. Insects can be triggered to feed on atypical food sources if the relevant aspects of their environment match those of their normal feeding environments. For example, here is a report from a professor of entomology recollecting his observations of being bitten by pea aphids while handling plants, which he assumes is because of the scent on his hands.
We can exploit this in various ways for research. One is for artificial blood-feeding of insects: most systems, like the Hemotek membrane feeding system, warm blood to the body temperature of the host. They do not normally resemble a target host in any other way. Some blood-feeding insects have very specific requirements for temperature (for example they will only feed on blood if it is heated to the body temperature of birds; the same blood heated to mammalian body temperature will be ignored) but we do not need to make the target look or smell like the natural host. Other species may need olfactory cues, which can be provided by researchers rubbing the membranes on their forearms before placing them on the feeding system, or by breathing on cages as you add the food.
A second way we exploit this is for insect traps. Although not all traps work this way, some work by mimicking the host and attracting insects that are looking for a meal. This can be via olfactory/chemical mimicry (for example carbon dioxide baited traps - try Googling "CO2-baited traps") or visual. Different degrees of visual 'deception' may be needed; for instance to attract tsetse flies, colour is important but shape is not:
The following is multiple choice question (with options) to answer.
Some protists hunt their food or act as what? | [
"parasites",
"reptiles",
"mammals",
"bats"
] | A | Some protists hunt their food or act as parasites. |
SciQ | SciQ-7039 | biochemistry, metabolism, enzymes, homeostasis
Title: Regulation of the TCA cycle and glycolysis by adenine nucleotides Why is the tricarboxylic acid cycle regulated by the ADP/ATP ratio as stated in the following quote :
Isocitrate dehydrogenase is allosterically stimulated by ADP, which enhances the enzyme's affinity for substrates.1
while glycolysis is regulated by AMP/ATP ratio as in the following quote from the same book :
Why is AMP and not ADP the positive regulator of phosphofructokinase? When ATP is being utilized rapidly, the enzyme adenylate kinase (Section 9.4) can form ATP from ADP by the following reaction: 2
The following is multiple choice question (with options) to answer.
Name what nutrient cycling is strongly regulated by. | [
"elevation",
"sunlight",
"vegetation",
"abundance"
] | C | |
SciQ | SciQ-7040 | Well, we said we were going to do it strictly by using your steam tables (to make sure I'm not trying to pull a fast one). Later, we can compare with the ideal gas law, but, for now I'd like to stick with the steam tables. Besides, if you assume an ideal gas, you still will have to deal with the problem of determining the internal energy and the enthalpy at the final state.
There are steam tables online that have the properties evaluated at 1.5 bar, if you want to avoid that interpolation (and I deliberately chose 1.5 bar because one of the specific volume values listed in the table at 1.5 bar is almost exactly our specific volume, so you wouldn't have to do any interpolating). However, if you can't find a steam table with 1.5 bar in it, I will settle for your using 1.6 bar. But then you will have to interpolate with respect to the specific volume to get the temperature, internal energy and enthalpy. Your choice.
Do you have any to recommend? So what's the value of u and h @ 1.5 bars & v = 1.6959 m3/kg
Chestermiller
Mentor
Do you have any to recommend? So what's the value of u and h @ 1.5 bars & v = 1.6959 m3/kg
I got one by googling "steam tables," but it was a PDF file, and I don't know how to get the actual URL. There are also steam tables in thermo books I have (that are consistent with the PDF table). In Moran et al, they give v = 1.695 m^3 at 280 C, with u = 2778.6 kJ/kg and h = 3032.8 kJ/kg. If you are comfortable using these values, we can continue.
Chet
This process of yours is better describe this way(p-v-t diagram). The two red lines are isotherms. Superheated steam @ 1 bar is raised to 1.6 bar at constant volume. This would mean one thing, you add up heat to the steam to raise its pressure at constant volume(obviously, since.transition is between 2 isotherms)
Applicable analysis would be ΔH = ΔU, since PΔV or flow work is zero.
The following is multiple choice question (with options) to answer.
Why must values of specific heat be looked up in tables? | [
"difficult to calculate",
"difficult to memorize",
"difficult to understand",
"lack of formulas"
] | A | Values of specific heat must generally be looked up in tables, because there is no simple way to calculate them. In general, the specific heat also depends on the temperature. Table 14.1 lists representative values of specific heat for various substances. Except for gases, the temperature and volume dependence of the specific heat of most substances is weak. We see from this table that the specific heat of water is five times that of glass and ten times that of iron, which means that it takes five times as much heat to raise the temperature of water the same amount as for glass and ten times as much heat to raise the temperature of water as for iron. In fact, water has one of the largest specific heats of any material, which is important for sustaining life on Earth. |
SciQ | SciQ-7041 | human-biology, evolution
Humans are off the charts in the amount of resources we invest in our children - our lives are 1/4 to 1/3 over before we sometimes leave our parents household (in some societies of course they never leave the house, but step into an extended family). This may be one of the reasons we are so successful as a species - we live in practically every place we possibly could and have no danger of competition from any other living thing excepting ourselves.
The grandmother effect is essentially the idea that if women, who are more attached to the offspring in more cases than fathers, continue to live and help support the grandchildren and make them more successful, then this will allow post menopausal women to have a longer lifespan (which they do).
The evolutionary biologist Sara Hrdy, emeritus UC Davis, has written quite a bit about the nuances of the evolution of the role of motherhood - reading some of her articles or books might give you a deeper sense of how profoundly filial love has shaped human beings.
--- more answer this stuff may or may not be worth reading depending on how broadly you want to understand this question...
Its important to say that many of the expansions of human average human lifespan have not been genetic. Its commonly cited that sewer systems, clean water, antibiotics and plentiful food are the three most important factors in human lifespan - and before modern developed world nations, the average lifespan of human beings was somewhere in the 30s. And there are significant lifespan differences in regions where these factors and others (education of women, access to prenatal and early care etc) are available.
Studies continue to be published that examine environmental and lifestyle factors compared to genetics and it seems that environment and lifestyle can make an astounding difference.
But genetics undoubtedly has a role to play here too. There are probably some individual humans and animals which have evolved to live longer. This has been found to be genetically related in some humans by demographics and family lines.
The following is multiple choice question (with options) to answer.
What is the method of evolution by which advantageous heritable traits become more common over generations? | [
"artificial selection",
"flow selection",
"natural selection",
"same selection"
] | C | The theory of evolution by natural selection was proposed at about the same time by both Charles Darwin and Alfred Russel Wallace, shown in Figure below , and was set out in detail in Darwin's 1859 book On the Origin of Species . Natural selection is a process that causes heritable traits that are helpful for survival and reproduction to become more common, and harmful traits, or traits that are not helpful or advantageous for survival to become more rare in a population of organisms. This occurs because organisms with advantageous traits are more "fit" to survive in a particular environment and have "adapted" to the conditions of that environment. These individuals will have greater reproductive success than organisms less fit for survival in the environment. This will lead to an increase in the number of organisms with the advantageous trait(s) over time. Over many generations, adaptations occur through a combination of successive, small, random changes in traits, and natural selection of those variants best-suited for their environment. Natural selection is one of the cornerstones of modern biology. |
SciQ | SciQ-7042 | electromagnetism, electrons, atomic-physics, orbital-motion
Title: What force is responsible to keep electrons in motion? Are electrons in an atom are in motion? If yes, then what force is responsible to keep electrons in motion in an atom? So roughly speaking this is the contents of Newton's first law.
Newton was living in an era when people wanted to think that the natural state was things standing still, and that all motion required a force to explain it. But but during Newton's life, Galileo had observed something different: when he rolled a smooth metal ball over a large flat floor, it had no intrinsic tendency to stop; it just wanted to keep going in a straight line. Newton elevated this idea to the status of a law of motion, saying that uniform motion in a straight line was the natural state, and deviations from that motion needed forces to explain them. So the fact that things slow down and eventually come to.rest, requires now an explanation (namely friction).
Indeed, to lose or gain energy now generally requires an explanation of where that energy went, until you get to galactic-scale systems and general relativity, where you cannot extend certain “local” definitions to apply “globally” any more. So the electron does not need, in this worldview, a special force to keep it moving: it just has to be prevented from losing the energy of motion that it has, to other systems. And that is the statement of quantum mechanics: this thing can only occupy certain discrete energy levels and there is no lower-energy “stopped” state available for the electron to fall into. The lowest state is not stopped because the electron has an intrinsic spin and when it occupies the non-rotating probability cloud spherically symmetric around the nucleus, that spin at each point looks like a rotation of the whole cloud. The higher states for e.g. Lithium, that one electron is not able to fall into the lower less-rotating energy states because they are already occupied by other electrons, so it must take one of the spinny energy states that has intrinsic orbital angular momentum.
The following is multiple choice question (with options) to answer.
Electrons move, but they aren’t destroyed. this is the law of conservation of what? | [
"matter",
"charge",
"cost",
"energy"
] | B | Like the formation of ions, the formation of charged matter in general depends on the transfer of electrons either between two materials or within a material. Three ways this can occur are friction, conduction, and polarization. In all cases, the total charge remains the same. Electrons move, but they aren’t destroyed. This is the law of conservation of charge . |
SciQ | SciQ-7043 | orbitals, periodic-trends
Note how the spacing between the lines decreases as we move to higher atomic number; also note that the slope of the lines tends to increase as the atomic numbers increases. Both of these observations illustrate what we have been discussing. As the atomic number increases there are more and more electrons between the outermost electron and the nucleus making it easier to remove that last electron and making the both the absolute and relative differences between successive ionizations (e.g. 1st IP and 2nd IP, 1st IP and 5th IP, etc.) smaller.
The following is multiple choice question (with options) to answer.
What type of orbitals do electrons in successive atoms on the periodic table tend to fill first? | [
"high energy",
"orbital lobes",
"outer orbitals",
"low-energy"
] | D | Electrons in successive atoms on the periodic table tend to fill low-energy orbitals first. Thus, many students find it confusing that, for example, the 5p orbitals fill immediately after the 4d, and immediately before the 6s. The filling order is based on observed experimental results, and has been confirmed by theoretical calculations. As the principal quantum number, n, increases, the size of the orbital increases and the electrons spend more time farther from the nucleus. Thus, the attraction to the nucleus is weaker and the energy associated with the orbital is higher (less stabilized). But this is not the only effect we have to take into account. Within each shell, as the value of l increases, the electrons are less penetrating (meaning there is less electron density found close to the nucleus), in the order s > p > d > f. Electrons that are closer to the nucleus slightly repel electrons that are farther out, offsetting the more dominant electron–nucleus attractions slightly (recall that all electrons have −1 charges, but nuclei have +Z charges). This phenomenon is called shielding and will be discussed in more detail in the next section. Electrons in orbitals that experience more shielding are less stabilized and thus higher in energy. For small orbitals (1s through 3p), the increase in energy due to n is more significant than the increase due to l; however, for larger orbitals the two trends are comparable and cannot be simply predicted. We will discuss methods for remembering the observed order. The arrangement of electrons in the orbitals of an atom is called the electron configuration of the atom. We describe an electron configuration with a symbol that contains three pieces of information (Figure 6.26): 1. The number of the principal quantum shell, n, 2. The letter that designates the orbital type (the subshell, l), and 3. A superscript number that designates the number of electrons in that particular subshell. |
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