source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
SciQ | SciQ-844 | botany, plant-physiology, reproduction, plant-anatomy, life-history
In dimorphic cleistogamy CL and CH flower differ in the time or place
of production, with CL flowers produced in conditions (underground,
low light levels, early in the season) that are potentially
unfavorable for outcrossing.
In induced cleistogamy potentially CH flowers that experience conditions such as drought or low temperatures fail to open and self-pollinate, becoming, in effect, CL flowers.
You should check out the Culley and Klooster (available online if you make a jstor login) – they discuss complete cleistogamy which addresses your last question. They report several completely CL species in their Table 1, and give references.
More generally, many different plant groups maintain balances of self-pollination and outcrossing (i.e. "real sex"), through an even more diverse set of mechanisms.
Even more generally, many plants and some animals maintain balances of sexual reproduction and clonal reproduction, through an even more diverse set of mechanisms. For instance, vegetative reproduction (e.g., strawberry runners) is very common in many plant groups; facultative and obligate parthenogenesis in animals also occurs.
Culley, Theresa M. and Matthew R. Klooster (2007). The Cleistogamous Breeding System: A Review of Its Frequency, Evolution, and Ecology in Angiosperms. Botanical Review. Vol. 73, No. 1, pp. 1-30
The following is multiple choice question (with options) to answer.
Flowers pollinated by what means generally lack brightly colored parts? | [
"bees",
"wind",
"butterflies",
"larvae"
] | B | |
SciQ | SciQ-845 | thermodynamics, temperature, everyday-life, phase-transition, humidity
Title: Steam from a cup of coffee I observed that, in winter there is more visible steam from a cup of coffee than in summer. Is there any phenomenon taking place here. The amount of water that air can take up before the water creates fog or visible steam depends on temperature. The colder the air, the less water it needs to create fog/steam. It is the same principle when hot air rises, for example when pushed up a mountain and then it starts to cool down drastically --> It will rain.
For more have a look at: Relative humidity in https://en.wikipedia.org/wiki/Humidity
The following is multiple choice question (with options) to answer.
Fog disappears when the water droplets change back to what? | [
"water vapor",
"solid vapor",
"ice vapor",
"cold vapor"
] | A | The water droplets of fog form from water vapor in the air. Fog disappears when the water droplets change back to water vapor. These changes are examples of changes of state. A change of state occurs whenever matter changes from one state to another. Common states of matter on Earth are solid, liquid, and gas. Matter may change back and forth between any two of these states. |
SciQ | SciQ-846 | combustion, temperature, fuel
Of course a lot of other factors are involved but this crude picture gives at least some useful insight. This was discovered experimentally in the early days of engine design as the designers observed that different extracts from oil had different combustion properties in engines and refined the way oil was distilled to give them the behaviours they wanted in their engines.
The following is multiple choice question (with options) to answer.
What is the name of the type of combustion engine that you would find in a car? | [
"internal oxide engine",
"internal vapor engine",
"internal combustion engine",
"internal modern engine"
] | C | A combustion engine is a complex machine that burns fuel to produce thermal energy and then uses the energy to do work. In a car, the engine does the work of providing kinetic energy that turns the wheels. The combustion engine in a car is a type of engine called an internal combustion engine. (Another type of combustion engine is an external combustion engine. ). |
SciQ | SciQ-847 | organic-chemistry, stereochemistry, cis-trans-isomerism
J. Verbeek, J. H. Van Lenthe, P. J. J. A. Timmermans, A. Mackor, and P. H. M. Budzelaar. "On the existence of trans-cyclohexene". J. Org. Chem. 1987, 52, 13, 2955–2957.
https://doi.org/10.1021/jo00389a067.
Michael E. Squillacote, James DeFellipis, and Qingning Shu
"How Stable Is trans-Cycloheptene?" J. Am. Chem. Soc. 2005, 127, 45, 15983–15988.
https://doi.org/10.1021/ja055388i
The following is multiple choice question (with options) to answer.
What must molecules have to be cis-trans isomers? | [
"single bond",
"triple bond",
"last bond",
"double bond"
] | D | Which of the following statements is false? a. Molecules with the formulas CH3CH2COOH and C3H6O2 could be structural isomers. Molecules must have a double bond to be cis-trans isomers. To be enantiomers, a molecule must have at least three different atoms or groups connected to a central carbon. To be enantiomers, a molecule must have at least four different atoms or groups connected to a central carbon. In triglycerides (fats and oils), long carbon chains known as fatty acids may contain double bonds, which can be in either the cis or trans configuration, illustrated in Figure 2.25. Fats with at least one double bond between carbon atoms are unsaturated fats. When some of these bonds are in the cis configuration, the resulting bend in the carbon backbone of the chain means that triglyceride molecules cannot pack tightly, so they remain liquid (oil) at room temperature. On the other hand, triglycerides with trans double bonds (popularly called trans fats), have relatively linear fatty acids that are able to. |
SciQ | SciQ-848 | energy, work
Title: Implications of Defining Work as Change in Mechanical Energy Would it be possible to form a theory of physics centered around the definition of work as the change in mechanical energy of an object/system, rather than the change in kinetic energy? What are some of the implications of using this definition? For instance, under this definition of work, conservative forces cannot do work on the system which defines the potential function, since they only exchange potential energy for kinetic energy.
Is there a reason why we rather define work as just the change in kinetic energy? I am wondering if my alternative definition would be practical, since I personally think it is more intuitive.
Would it be possible to form a theory of physics centered around the
definition of work as the change in mechanical energy of an
object/system, rather than the change in kinetic energy?
We don't "define" work this way. When we talk about work and change in kinetic energy we are referring to the work energy theorem which states:
The net work done on an object equals its change in kinetic energy.
Bold face is mine to emphasize that we are talking about net work and not just work. This is necessary because work can be negative or positive. If the net work is positive, the kinetic energy of the object increases, negative it decreases, and zero no change in kinetic energy.
But no change in kinetic energy does not necessarily mean no change in potential energy which is a system property and not a property of an object alone. For example, if we lift an object of mass $m$ an height from the ground $h$ starting from rest and ending at rest at $h$ the change in kinetic energy is zero. The positive work w do lifting the object equals the negative work done by gravity. The work done by gravity is negative because the direction of the force of gravity is opposite to the displacement of the object. Gravity takes the energy we gave the object and stores it as gravitational potential energy of the earth/object system.
For instance, under this definition of work, conservative forces
cannot do work on the system which defines the potential function,
since they only exchange potential energy for kinetic energy.
The following is multiple choice question (with options) to answer.
In physics, work means the use of what to move an object? | [
"force",
"leverage",
"mass",
"energy"
] | A | Work is defined differently in physics than in everyday language. In physics, work means the use of force to move an object. The teens who are playing basketball in the picture above are using force to move their bodies and the basketball, so they are doing work. The teen who is studying isn’t moving anything, so she isn’t doing work. Not all force that is used to move an object does work. For work to be done, the force must be applied in the same direction that the object moves. If a force is applied in a different direction than the object moves, no work is done. The Figure below illustrates this point. |
SciQ | SciQ-849 | particle-physics, electromagnetic-radiation, radiation, radioactivity, gamma-rays
Title: How to produce ionizing radiation without radioactive substance? I think ionizing radiation caused by ray or particles.
My professor told me:"without radioactive substance,with only commercial products,it's possible to produce ionizing radiation."
Can anyone give me some thoughts about the methodology. Ultraviolet light is capable of ionizing a variety of substances; this effect is quite strong and allows UV to be used to disinfect drinking water and kill bacteria as well as giving you a sunburn.
The following is multiple choice question (with options) to answer.
Types of radiation that cause cancer include ultraviolet (uv) radiation and what? | [
"molecular",
"radon",
"thermal",
"vibrational"
] | B | Types of radiation that cause cancer include ultraviolet (UV) radiation and radon. UV radiation is part of sunlight. It is the leading cause of skin cancer. Radon is a naturally occurring radioactive gas that escapes from underground rocks. It may seep into the basements of buildings. It can cause lung cancer. |
SciQ | SciQ-850 | metabolism, nutrition
Title: What are calories and how to burn them? What exactly is a calorie? When burning calories, do we always lose fat?
I have tried many apps to measure calories, do they give exact amounts? How many calories should be taken a day? A calorie is a measure of energy. In nutrition, we usually mean the kilocalorie (kcal), which is the same as about 4.2 kJ (kilojoule). A average person needs about 2,000--2,500 kcal per day, but this of course varies quite a bit between people, depending on size (muscle mass, particularly) and level of physical activity (physical work, exercise).
Nutrition guidelines found on the labels of food products give a pretty good summary of the amount of energy they contain. I'm not sure what applications you have been using, but they most likely rely on the same basic data, so the values should be similar. You can use these values to figure out roughly what your calorie intake is, and to spot very calorie-rich foods. But counting calories exactly is actually quite difficult --- you need to carefully weigh everything you eat and keep track of lots of numbers, and it's easy to make mistakes.
Burning calories does not always mean burning fat. Fat is a long-term energy storage form in the body. When exercising, the body tends to burn stored carbohydrates (glycogen) first, and turns to burning fat when carbohydrates are exhausted. Therefore, prolonged, low-intensity exercise like long walks are usually better for burning fat than short "sprint" type of exercise. The body also burns fat during normal daily activity if your energy intake is lower than the daily need (when dieting). But it is also possible that some muscle mass is degraded (to amino acids) and used for energy as well.
See also Wikipedia articles on food energy and exercise. Please note that "how to burn calories" is a heavily debated issue, there is an entire industry of weight loss methods, and various claims about "easy" methods or products to lose weight quickly are generally not true. The only reliable method to lose weight is to reduce food intake and increase exercise, for a long period of time.
The following is multiple choice question (with options) to answer.
How many calories of energy does one gram of sugar or starch provide? | [
"5",
"10",
"3",
"4"
] | D | Carbohydrates include sugars, starches, and fiber. Sugars and starches are used by the body for energy. One gram of sugar or starch provides 4 Calories of energy. Fiber doesn’t provide energy, but it is needed for other uses. At age 13 years, you need about 130 grams of carbohydrates a day. Figure below shows good food sources of each type. |
SciQ | SciQ-851 | terminology, human-physiology, organs
Title: Medical term for "holding urine for a long time" Sometimes I get/feel pain in my stomach because of holding urine for long time. Is there any medical terminology describing: "holding urine for a long time", or pain associated with this activity? A swollen organ may be described as distended if the swelling is symptomatic of a medical disfunction.
The purpose of most bladders is to collect and retain a fluid; if that fluid needs to be discharged periodically, and is not able to do so, then there is usually pain as a result of the distension.
Inability to urinate is known as ischuria or urinary retention, and could be the result of obstruction to the urethra, could be a failure of the bladder to fully contract during urination, or could many other possible causes.
The following is multiple choice question (with options) to answer.
Defecating, urination, and even childbirth involve cooperation between the diaphragm and these? | [
"skeletal muscles",
"heart muscles",
"lung muscles",
"abdominal muscles"
] | D | Defecating, urination, and even childbirth involve cooperation between the diaphragm and abdominal muscles (this cooperation is referred to as the “Valsalva maneuver”). You hold your breath by a steady contraction of the diaphragm; this stabilizes the volume and pressure of the peritoneal cavity. When the abdominal muscles contract, the pressure cannot push the diaphragm up, so it increases pressure on the intestinal tract (defecation), urinary tract (urination), or reproductive tract (childbirth). The inferior surface of the pericardial sac and the inferior surfaces of the pleural membranes (parietal pleura) fuse onto the central tendon of the diaphragm. To the sides of the tendon are the skeletal muscle portions of the diaphragm, which insert into the tendon while having a number of origins including the xiphoid process of the sternum anteriorly, the inferior six ribs and their cartilages laterally, and the lumbar vertebrae and 12th ribs posteriorly. The diaphragm also includes three openings for the passage of structures between the thorax and the abdomen. The inferior vena cava passes through the caval opening, and the esophagus and attached nerves pass through the esophageal hiatus. The aorta, thoracic duct, and azygous vein pass through the aortic hiatus of the posterior diaphragm. |
SciQ | SciQ-852 | electrostatics
http://en.wikipedia.org/wiki/Electronegativity#Electronegativities_of_the_elements
The redder atom, the higher electronegativity, and the more likely it is for the atom to gain electrons and become negatively charged. That's especially true for light halogens (fluorine, chlorine) and oxygen. That's partly why glass - with lots of $SiO_2$ - likes to get negatively charged in the triboelectric effect. Even sulfur (40% of ebonite) has a higher electronegativity than e.g. carbon and hydrogen that are abundant in the fur which is why fur loses electrons and becomes positively charged.
Of course, the actual arrangement of the atoms in the molecules matters, too. So this overview of the periodic table was just an analogy, not a reliable way to find out the results of the triboelectric effect.
The following is multiple choice question (with options) to answer.
When we move down a group of elements on the periodic table, what happens to their electronegativity? | [
"it doubles",
"it stays the same",
"it decreases",
"it increases"
] | C | The nonmetals are elements located in the upper right portion of the periodic table. Their properties and behavior are quite different from those of metals on the left side. Under normal conditions, more than half of the nonmetals are gases, one is a liquid, and the rest include some of the softest and hardest of solids. The nonmetals exhibit a rich variety of chemical behaviors. They include the most reactive and least reactive of elements, and they form many different ionic and covalent compounds. This section presents an overview of the properties and chemical behaviors of the nonmetals, as well as the chemistry of specific elements. Many of these nonmetals are important in biological systems. In many cases, trends in electronegativity enable us to predict the type of bonding and the physical states in compounds involving the nonmetals. We know that electronegativity decreases as we move down a given group and increases as we move from left to right across a period. The nonmetals have higher electronegativities than do metals, and compounds formed between metals and nonmetals are generally ionic in nature because of the large differences in electronegativity between them. The metals form cations, the nonmetals form anions, and the resulting compounds are solids under normal conditions. On the other hand, compounds formed between two or more nonmetals have small differences in electronegativity between the atoms, and covalent bonding—sharing of electrons—results. These substances tend to be molecular in nature and are gases, liquids, or volatile solids at room temperature and pressure. In normal chemical processes, nonmetals do not form monatomic positive ions (cations) because their ionization energies are too high. All monatomic nonmetal ions are anions; examples include the chloride ion, Cl−, the nitride ion, N3−, and the selenide ion, Se2−. The common oxidation states that the nonmetals exhibit in their ionic and covalent compounds are shown in Figure 18.19. Remember that an element exhibits a positive oxidation state when combined with a more electronegative element and that it exhibits a negative oxidation state when combined with a less electronegative element. |
SciQ | SciQ-853 | biochemistry, photosynthesis
Title: When is Water Produced During Photosynthesis? The formula for photosynthesis is: $$6CO_2+12H_2O \rightarrow C_6H_{12}O_6+6O_2+6H_2O$$
I can count the carbons, the waters on the reactant side, the oxygens, and the glucose, but I cannot seem to locate where in either light or dark reaction 6 water molecules were produced again. Where and when were they produced? Some of the water that's split is regenerated when the hydroxyl radicals (reactive oxygen species) are converted to hydrogen peroxide, water, etc. by superoxide dismutases and antioxidative mechanisms in the chloroplast (peroxisomes/catalases, etc. take care of this). There's also some evidence that the presence of mannitol, ascorbate and glutathione protect against ROS produced in chloroplasts as well. So you input water, and in an effort to avoid oxidative damage, you do get some water generated. However, the balanced equation doesn't reflect this because it's not an actual product of photosynthesis.
About ROS and protective elements
Extra Reading on ROS in photosynthetic systems
I think that's a very obscure fact, and despite the reality of things, it's actually difficult to query the literature. Good question.
The following is multiple choice question (with options) to answer.
What two elements do chloroplasts split water into? | [
"vaporize and oxygen",
"Salt and sodium",
"hydrogen and oxygen",
"Carbon and water"
] | C | |
SciQ | SciQ-854 | organic-chemistry
(image credit to Xu et al.)
An advanced version of this would be to set up flow chemistry, a topic for which for instance the group by Steven Ley (Cambridge UK) is known for:
(image credit Ley group)
To design this, one needs to know the underlying kinetic data; then, chemical engineering steps in e.g., to estimate a useful time of residence in these tube reactors. But once installed, up and running, the steady state of the continuous flow allows some operations (too) difficult/dangerous to apply with round bottom flasks, including lithiation reactions.
The author of schlenklinesurvivalguide.com equally compiled his experiences in a paper: Borys, A. M. An Illustrated Guide to Schlenk Line Techniques. Organometallics 2023, 42, 182–196. https://doi.org/10.1021/acs.organomet.2c00535.
Xu, H.-C.; Chowdhury, S.; Ellman, J. A. Asymmetric Synthesis of Amines Using Tert-Butanesulfinamide. Nat. Protoc. 2013, 8, 2271–2280. https://doi.org/10.1038/nprot.2013.134 (author's copy on Researchgate).
Brégent, T.; Ivanova, M. V.; Poisson, T.; Jubault, P.; Legros, J. Continuous‐Flow Divergent Lithiation of 2,3‐Dihalopyridines: Deprotolithiation versus Halogen Dance. Chem. Eur. J. 2022, 28, e202202286. https://doi.org/10.1002/chem.202202286 (open access).
Power, M.; Alcock, E.; McGlacken, G. P. Organolithium Bases in Flow Chemistry: A Review. Org. Process Res. Dev. 2020, 24, 1814–1838. https://doi.org/10.1021/acs.oprd.0c00090 (author's copy here).
The following is multiple choice question (with options) to answer.
Continuous-flow reactors are chemical reaction vessels in which the what are mixed and allowed to react as they flow along a tube? | [
"reactants",
"propellants",
"reactives",
"generators"
] | A | ♦ Many industrial processes for preparing compounds use “continuous-flow reactors,” which are chemical reaction vessels in which the reactants are mixed and allowed to react as they flow along a tube. The products are removed at a certain distance from the starting point, when the reaction is nearly complete. The key operating parameters in a continuous-flow reactor are temperature, reactor volume, and reactant flow rate. As an industrial chemist, you think you have successfully modified a particular process to produce a higher product yield by substituting one reactant for another. The viscosity of the new reactant is, however, greater than that of the initial reactant. |
SciQ | SciQ-855 | error-analysis
Title: Why aren't the 0's significant figures in 0.002? I understand that significant figures is a term used for "reliably known digits". However, what I don't understand is why the 0's are not counted among these in numbers such as 0.002. Surely, if we know that the units digit is 0, and that the tenths digit is 0, and that the hundredths digit is 0, then we know these digits reliably? In other words, we know that the units digit is not 1 or 2 or 3, but 0. Thus, we know this digit reliably. Why then is it not counted as a significant figure? Why do all physics textbooks say that 0.002 only has 1 significant figure?
The "related" question is different from the one I am asking. The one there is asking about 1500 whereas my one is about 0.002, ie when the zeros come to the left of the number. One of the logical rules for significant figures is that expressing a given number in a different order of magnitude should not make you sound like you know more or less about the number. If you start with $0.002$, we can only say that it's equal to $2\times 10^{-3}$, since you probably already appreciate the implications of adding zeros to the left of a decimal place.
Regarding the claim,
we know that the units digit is not 1 or 2 or 3
Yes, but those are extremely trivial bits of knowledge. Try saying "$002$ has three significant figures". It's obvious that there's no other constant in those places, because then we'd be dealing with a completely different number; you wouldn't call it "two". Significant figures are only a relevant thing to consider when you're debating between options which can be rounded to the same value, within reason.
The following is multiple choice question (with options) to answer.
What is it called when one or more ending digits are dropped to get the correct number of significant figures? | [
"rounding",
"scientific notation",
"basing",
"turning"
] | A | Rounding is done when one or more ending digits are dropped to get the correct number of significant figures. Simple rules state when to round up and when to round down. |
SciQ | SciQ-856 | human-biology, hair
In most people this receptor functions as intended, and melanocytes in the skin produce varying degrees of brown-black eumelanin (the extent of which depending on one's ethnic background) while pheomelanin is switched on in the few key areas listed above. When both copies of the MC1R gene inherited from each of your parents are disfunctional, this switching mechanism no longer works and your melanocytes will produce primarily pheomelanin ubiquitously across your body. This is what we know as 'redheads'.
What isn't immediately obvious is that red-haired individuals are not unique in just the aspect of their hair. Their whole body presents with a deficiency in eumelanin and as such they also carry a pale/rosy complexion as well as an inability to tan and a propensity to sunburn easily. This is a consequences of the fact that eumelanin is our primary defense against UV radiation.
While melanocytes in the skin and eyes are responsible for the production of melanin, the melanin in one's hair gets there as a result of a handoff between melanocytes and the keratin producing keratinocytes. Melanin within melanocytes is produced and stored within organelles known as melanosomes and, through a complex formed by the 3 genes MYO5A, RAB27A, and MLPH, the transfer of these melanosomes through the tendrils of the melanocytes to the keratinocytes is facilitated. Defects in any of these 3 genes can result in a condition known as Griscelli syndrome (types 1, 2, and 3, respectively) where the transfer of melanin from melanocytes to keratinocytes is impaired.
The following is multiple choice question (with options) to answer.
Hair sticks out from the epidermis, but it grows from the? | [
"humus",
"dermis",
"fat",
"bone"
] | B | Hair is one of the defining characteristics of mammals. In fact, mammals are the only animals to have hair. Hair sticks out from the epidermis, but it grows from the dermis ( Figure below ). Hair grows from inside the hair follicle . New cells grow in the bottom part of the hair, called the bulb. Older cells get pushed up, and the hair grows longer. The cells that make up the hair strand are dead and filled with the rope-like protein keratin. |
SciQ | SciQ-857 | galaxy, milky-way
Title: Milky Way Galaxy from Earth I've seen a lot of beautiful pictures of the Milky Way from Earth such as this:
...but I can't understand what the cloudy ribbon at the bottom the horizon is. Is it a super-large nebula? Or is it due to the Gegenschein? What happens in the ribbon? The Milky Way Galaxy is a large spiral galaxy with some characteristic features worth mentioning:
1) The bulge - This refers to the collection of tightly packed stars located in the central region of the galaxy.
2) The spiral arms or the disk - This region extends from the inner region of the galaxy (where it meets the bulge) to outskirts of the galaxy, and contains stars, dust, and lots of gas. It's also very thin. The reason why a disk forms is largely thought to be due to slight asymmetries in the accretion of material early on in the galaxy's history. Over time, and due to conservation of angular momentum, the material collapses down into a disk. Incidentally, this is where the sun lives.
That ribbon is the disk of the Milky Way. It looks cloudy because of the dust and gas which scatters light from the rest of the galaxy. The reason why gas accumulates here is because as things begin to collapse into a disk, the gas collides with itself, and sort of 'sticks' together. In other words, where a bunch of stars may very happily pass through a bunch of other stars without many of them colliding or being disturbed, gas has a much harder time doing this. If you want to learn more about what happens when galaxies and clusters collide, take a look at the Bullet Cluster.
The majority of the other stars you you see which are not part of that structure are much more local. The reason why the rest of the sky looks rather transparent in comparison is because you are looking out of the plane of the galaxy. There is simply much less stuff (namely gas and dust which obscures your sight in optical wavelengths) that you are looking through. Because of this, most optical telescopes look in these directions when studying the rest of the universe.
For more about the classification and structures of galaxies, see the Hubble sequence.
The following is multiple choice question (with options) to answer.
The milky way galaxy is which shape type of galaxy? | [
"helical",
"spherical",
"cylindrical",
"spiral"
] | D | The Milky Way Galaxy is a spiral galaxy that contains about 400 billion stars. Like other spiral galaxies, it has a disk, a central bulge, and spiral arms. The disk is about 100,000 light-years across. It is about 3,000 light years thick. Most of the galaxy’s gas, dust, young stars, and open clusters are in the disk. Some astronomers think that there is a gigantic black hole at the center of the galaxy. Figure below shows what the Milky Way probably looks like from the outside. |
SciQ | SciQ-858 | tropical-cyclone, barometric-pressure
Also, a figure from Stull showing the difference in temperature within the hurricane core relative to surroundings:
That perhaps makes it more sensible that the warmer core air cannot continue subsiding down to the near-sea surface low at base of the core, where the air is very moist, but at lower temperature (might consider this to be a high stopping on encounter with a low).
The following is multiple choice question (with options) to answer.
Atmospheric pressure is low in what anatomically named part of a hurricane? | [
"leg",
"nose",
"mouth",
"eye"
] | D | Atmospheric pressure is low in the eye of a hurricane. In a 1979 hurricane in the Pacific Ocean, a pressure of 0.859 atm was reported inside the eye. What is this pressure in torr?. |
SciQ | SciQ-859 | diffusion
The reverse process is also happening with molecules diffusing from right to left at a rate proportional to their concentration in the right side solution. As the concentration on the right side increases to be equal to the concentration on the left, so the diffusion rates become equal and there is zero nett diffusion and the system approaches equilibrium.
Note that this assumes a "perfect" system where there is no chemical reaction occurring between the solutes or between the solutes and the membrane. In practice this means that either the interaction between solutes A and B is the same as the interaction between the solutes and the solvent or that the solute molecules are so greatly outnumbered by the solvent molecules that the solute-solute interactions are not significant.
The rate of diffusion of solute A may be different from B (i.e. the proportionality constant between rate and concentration may be different). This means that before reaching equilibrium the relative concentrations of A and B may change but at equilibrium, the relative concentration will be the same as initially.
If we define "reaching equilibrium" as having some fraction (say 99.99%) of the final concentration then increasing the initial global concentration will increase the lag for both solutes equally and will not change their relative concentrations.
The following is multiple choice question (with options) to answer.
What occurs when a substance diffuses through a cell membrane without any help from other molecules? | [
"simple filtration",
"simple diffusion",
"visual diffusion",
"visible diffusion"
] | B | Simple diffusion occurs when a substance diffuses through a cell membrane without any help from other molecules. The substance simply passes through tiny spaces in the membrane. It moves from the side of the membrane where it is more concentrated to the side where it is less concentrated. You can see how this happens in Figure below . |
SciQ | SciQ-860 | bond, ions, ionic-compounds
Title: Why is the overall charge of an ionic compound zero?
My textbook simply says:
Since an ionic compound consists of equal number of positive and negative ions, the overall charge of an ionic compound is zero.
But why is the number of positive and negative ions equal?
Can’t an ionic compound can have an unequal number of negative and positive ions? Why or why not? Sodium needs to lose 1 Electron to attain stable electronic configuration and chlorine needs to gain 1 electron to stable electronic configuration.
In a big picture, the electron was transferred from sodium to chlorine in the same neutral crystal. No electron was supplied to the crystal from outside, it was already in the same system before and after the formation of NaCl.
If the system before formation of NaCl was neutral then it will be neutral even after the formation of NaCl crystal. That may be the reason.
The following is multiple choice question (with options) to answer.
Sodium and chloride ions have equal but what charges? | [
"simple",
"positive",
"opposite",
"path"
] | C | Sodium and chloride ions have equal but opposite charges. Opposite electric charges attract each other, so sodium and chloride ions cling together in a strong ionic bond. You can see this in row 2 of the Figure above . (Brackets separate the ions in the diagram to show that the ions in the compound do not actually share electrons. ) When ionic bonds hold ions together, they form an ionic compound. The compound formed from sodium and chloride ions is named sodium chloride. It is commonly called table salt. You can see an animation of sodium chloride forming at this URL: http://www. visionlearning. com/library/module_viewer. php?mid=55. |
SciQ | SciQ-861 | quantum-mechanics, operators, measurement-problem, eigenvalue, observables
If you measure the length of a piece of paper with a ruler for example, you will not obtain a different result when you measure it again.
When you now measure a quantum system, you have two types of statistics in there. First, your particle exhibits certain probabilities to be at a certain location. Secondly, your measurement apparatus is never 100% precise. The best you can do is perform lots of different measurements of identically prepared systems which is also a source of uncertainty because identical preparation might be difficult in real life. You will obtain the probability of presence of the particle at a certain position. But since the position is a continuous variable, there will always be an error. You can never measure "true values" but you will not be "limited by the collapsed state" as you formulated it.
The following is multiple choice question (with options) to answer.
What is making measurements that are close to the true value known as? | [
"accuracy",
"prediction",
"frequency",
"estimation"
] | A | Accuracy means making measurements that are close to the true value. |
SciQ | SciQ-862 | molecular-biology, neurotransmitter, muscles, receptor
Is the membrane continuous along these tubules, or does the tubule just end somewhere inside the muscle fiber?
The membranes are continuous.
When the muscle is twitching... is this neurological of nature, or is it related to a molecular cause in the muscle itself?
Most things you'd call a muscle twitch are at the whole-muscle-group scale, involving the coordinated contraction of many individual motor units, so it's basically neurological.
When the muscle is cramping... I'm almost certain this arises in the muscle. What causes it? A malfunction with regard to the calcium ions?
A muscle cramp is a colloquialism for a couple of things that are quite different from each other. Overall, as with the previous question, if someone's experiencing a muscle cramp that means it's a fairly macroscopic phenomenon and it likely involves a whole group of muscle filaments, so it's neurological. Most spasms and cramps are neurologically mediated.
The connections with electrolyte balances (cramps from low sodium, potassium, magnesium, or calcium) also hint at the neurological basis because neurons act on each other (and on muscles) by forming or dissipating ion gradients. You may know that low dietary calcium can lead to muscle cramps; if this was relevant to the calcium release within the myocyte (from the sarcoplasmic reticulum) then the calcium-starved muscles wouldn't be expected to chronically contract (which requires calcium) but to chronically relax.
That being said, there's a lot of room for feedback mechanisms. So, let's say a person experiences a muscle tear; the tear is small enough that it doesn't compromise the function of the entire muscle group. In this case it's adaptive for the local damage to 'signal' to the rest of the muscle group to initiate spasm so as to stabilize the damaged structures as they're repaired. In this scenario the local damage would 'inform' a neurological (and/or endocrine) response that actually effects the spasm.
Lastly, and on a slightly different subject, what are the microlesions in the muscles that occur during strength training, and what is the overcompensation that happens?
The following is multiple choice question (with options) to answer.
What are muscle cells in the muscles called? | [
"human fibers",
"job fibers",
"muscle fibers",
"use fibers"
] | C | The muscular system consists of all the muscles of the body. Muscles are organs composed mainly of muscle cells, which are also called muscle fibers . Each muscle fiber is a very long, thin cell that can do something no other cell can do. It can contract, or shorten. Muscle contractions are responsible for virtually all the movements of the body, both inside and out. There are three types of muscle tissues in the human body: cardiac, smooth, and skeletal muscle tissues. They are shown in Figure below and described below. |
SciQ | SciQ-863 | thermodynamics, equilibrium, entropy, free-energy
The minimum in G occurs because the entropy term $-TS$ has a minimum as the mole fraction of B increases (at constant T). Initially it is the entropy of A alone in solution, but at equilibrium is a mixture of A and B. If the reaction goes entirely to B then the entropy is that of B alone. The entropy of a mixture is naturally greater than that of one species thus $-TS$ has a minimum vs. $\zeta$.
If $dn_A$ and $dn_B$ of A and B molecules react the the infinitesimal change in zeta is $d\zeta = dn_A-dn_B$. The total change in free energy is $dG=\mu_Adn_A+\mu_Bdn_B$ where $\mu$ is the chemical potential or the free energy / mole. From these two equations the change in free energy of the reaction is
$$dG=(\mu_b-\mu_A)d\zeta$$
The reaction proceeds until $(\partial G/\partial \zeta)_{T,P} = 0$ and thus to proceed further expressions for the chemical potential are needed. For a perfect gas $\mu=\mu^0+RT\ln(p) $ thus
$$(\partial G/\partial \zeta)_{T,P} = \mu^0_B-\mu^0_A+RT\ln\frac{p_B}{p_A}$$
which can be recast as
$$(\partial G/\partial \zeta)_{T,P} = \Delta G^0+RT\ln\frac{p_B}{p_A}$$
and at equilibrium as the derivative is zero
$$\Delta G^0=-RT\ln\frac{p_B}{p_A}=-RT\ln K_p$$
which connect the equilibrium constant ($K_P$ for the gas phase reaction), with the free energy.
The following is multiple choice question (with options) to answer.
What term means the minimum energy required in order for a collision between molecules to result in a chemical reaction? | [
"activation energy",
"solar energy",
"depletion energy",
"maximum energy"
] | A | Summary A minimum energy (activation energy, Ea) is required for a collision between molecules to result in a chemical reaction. Plots of potential energy for a system versus the reaction coordinate show an energy barrier that must be overcome for the reaction to occur. The arrangement of atoms at the highest point of this barrier is the activated complex, or transition state, of the reaction. At a given temperature, the higher the Ea, the slower the reaction. The fraction of orientations that result in a reaction is the steric factor. The frequency factor, steric factor, and activation energy are related to the rate constant in the Arrhenius equation: k = Ae - Ea / RT. A plot of the natural logarithm of k versus 1/T is a straight line with a slope of −Ea/R. Saylor URL: http://www. saylor. org/books. |
SciQ | SciQ-864 | thermodynamics, statistical-mechanics
mass and other things related to work are kept constant.
(For readers unfamiliar with partial differentiation, I offer some simpler thoughts at the end. Here I am being completely precise and thorough).
In order to use this second definition, we need to know what entropy is. One way to figure out what entropy is is to use the first temperature definition, plus some more clever reasoning named after Clausius, and eventually define entropy such that the second result holds. But you can if you like just assert that physical systems have a property called entropy, and assert some very general facts about it (e.g. it can only ever stay constant or increase in an isolated system), and then arrive at equation (2)
as a definition of what we even mean by temperature (not just an assertion
about temperature). In this approach it is normally felt to be more insightful to write it the other way up:
$$
\frac{1}{T} \equiv \left. \frac{\partial S}{\partial U} \right|_{V, m,\, \rm etc.}
\tag{3}
$$
Equations (2) and (3) are saying precisely the same thing; I have just taken an inverse on both sides.
I have now shown that temperature is a macroscopic concept because I have only needed macroscopic physical ideas and quantities (energy, entropy, mass, volume) to define and describe it precisely.
The following is multiple choice question (with options) to answer.
What term is used to describe the change in size or volume of a given mass with temperature? | [
"thermal contraction",
"atmospheric expansion",
"freezing",
"thermal expansion"
] | D | The expansion of alcohol in a thermometer is one of many commonly encountered examples of thermal expansion, the change in size or volume of a given mass with temperature. Hot air rises because its volume increases, which causes the hot air’s density to be smaller than the density of surrounding air, causing a buoyant (upward) force on the hot air. The same happens in all liquids and gases, driving natural heat transfer upwards in homes, oceans, and weather systems. Solids also undergo thermal expansion. Railroad tracks and bridges, for example, have expansion joints to allow them to freely expand and contract with temperature changes. What are the basic properties of thermal expansion? First, thermal expansion is clearly related to temperature change. The greater the temperature change, the more a bimetallic strip will bend. Second, it depends on the material. In a thermometer, for example, the expansion of alcohol is much greater than the expansion of the glass containing it. What is the underlying cause of thermal expansion? As is discussed in Kinetic Theory: Atomic and Molecular Explanation of Pressure and Temperature, an increase in temperature implies an increase in the kinetic energy of the individual atoms. In a solid, unlike in a gas, the atoms or molecules are closely packed together, but their kinetic energy (in the form of small, rapid vibrations) pushes neighboring atoms or molecules apart from each other. This neighbor-to-neighbor pushing results in a slightly greater distance, on average, between neighbors, and adds up to a larger size for the whole body. For most substances under ordinary conditions, there is no preferred direction, and an increase in temperature will increase the solid’s size by a certain fraction in each dimension. Linear Thermal Expansion—Thermal Expansion in One Dimension The change in length ΔL is proportional to length and length is summarized in the equation. |
SciQ | SciQ-865 | quantum-mechanics, electrons
Title: What happens where an electron is annihilated by a spontaneously generated positron-electron pair? I was visiting the Australian Synchrotron earlier today as part of a tour group; as the guide was going over the booster and storage rings I was reminded of something I learnt of quantum.
If I know my quantum well enough, every so often, there are spontaneous pairs of electrons and positrons created and destroyed everywhere. Now I know that they don't last very long, but I got to thinking, what would happen if a pair was created at just the right instant for the positron to collide with one of the super-high-energy electrons in the booster or storage ring of a synchrotron?
When I asked our guide he said that the probability was pretty low since there were only 1x10^6 electrons in there and naturally the pair would have to generate at just the right spot at just the right time. Ultimately he wasn't quite sure what would happen if the circumstances were correct for it though.
I have been doing some further thinking, if I remember correctly, these pairs form as an electron spiralling in towards a central positron. I think that therefore at ordinary energies any nearby electrons would be repelled by the electron around the positron (which is a little reminiscent of the atomic stuff of first year chemistry).
Question is, could an electron, at the sorts of energy levels of the order of giga-electron-volts, get past the spiralling electron and collide with the positron instead of its paired electron doing so? As this energy could not simply vanish, would you then get a lonely (now unpaired) electron and an explosion? or would the energy somehow transfer itself to the other electron?
My interest here is towards what would actually happen if all circumstances were just right; also appreciated would be anyone who might be able to tell me the theoretical frequency of electron-positron pairs being spontaneously generated, as well as helping me to think up a way of determining the probability of finding an electron within one of the rings (for instance, perhaps if electrons can be considered to have an effective 'volume' within which they are most likely to appear and comparing that to the volume of the ring?)
The following is multiple choice question (with options) to answer.
What are created based upon the loss or gain of electrons? | [
"ions",
"hydrogens",
"atoms",
"crystals"
] | A | Christopher Auyeung. Ions are created by the loss or gain of electrons . CC BY-NC 3.0. |
SciQ | SciQ-866 | 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 atoms of the same element have the same number of what? | [
"charge",
"protons",
"electrons",
"molecules"
] | B | Atomic Number In the 1910s, experiments with X rays led to this useful conclusion: the magnitude of the positive charge in the nucleus of every atom of a particular element is the same. In other words, all atoms of the same element have the same number of protons. Furthermore,. |
SciQ | SciQ-867 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
What kind of chain is formed by subduction of oceanic crust beneath a continental or oceanic plate? | [
"tsunami",
"chain reaction",
"mountain",
"volcano"
] | D | Subduction of oceanic crust beneath a continental or oceanic plate creates a chain of volcanoes. |
SciQ | SciQ-868 | cell-biology
Title: Are there human cells, apart from red blood cells and platelets, without a nucleus? I know that blood platelets and erythrocytes do not have a nucleus. Are there more cells in the human body without a nucleus, such as pancreas, cartilage, or lung cells? Short answer
As far as I know, red blood cells and blood platelets are the only human cells in our body without a nucleus.
Background
Erythrocytes and thrombocytes are the only human cells without a nucleus, as far as I know. However, if you count the gut as being part of the human body (in essence it is a continuation of the skin and as such it can be considered to be on our outside), then we are loaded with cells lacking a nucleus, namely all the bacteria that live in our intestines such as E. coli. Bacteria, being prokaryotes, lack a nucleus. In fact, there are ten times more bacteria than human cells in our gut (Wenner, 2007).
Reference
Wenner, Sci Am 2007
The following is multiple choice question (with options) to answer.
Which kinds of cells have nuclei and other membrane bound organelles? | [
"eukaryotes",
"monocytes",
"lipids",
"prokaryotes"
] | A | Like the cells of all eukaryotes, animal cells have a nucleus and other membrane-bound organelles. Unlike the cells of eukaryotes in the Plant and Fungus Kingdoms, animal cells lack a cell wall. This gives animal cells flexibility. It lets them take on different shapes. This in turn allows them to become specialized for particular jobs. |
SciQ | SciQ-869 | human-biology
Title: Stopping the effect of hormone Many hormones released by endocrine organs travel down in the blood and bind to specific receptors on the target cells. What then breaks that binding of the molecule with the receptor ? ( thus inactivating further stimulation of the target cell ) The binding is reversible typically; part of the potency of a drug is ow well and for how long it binds to its target. There's a natural equilibrium of binding and dissociation. Many drugs, once bound to their cognate receptor, cause a down regulation of their cognate receptor on the target cell. The bound/activated downstream signalling pathways may be inhibited by ubiquitination of the downstream signals themselves or upregulation of antagonists etc. The hormone itself has a half life, which is very important, thus levels naturally decrease and for some hormones this is incredibly rapid. Levels may decrease due to breakdown or excretion. Increase of binding hormones may decrease free hormone thus it's effect also.
The following is multiple choice question (with options) to answer.
What regulates the thyroid gland in a body? | [
"upper feedback loop",
"positive feedback loop",
"normal feedback loop",
"negative feedback loop"
] | D | The thyroid gland is regulated by a negative feedback loop. The loop includes the hypothalamus and pituitary gland in addition to the thyroid. |
SciQ | SciQ-870 | zoology, marsupials
Title: Do male marsupials have a pouch? Do male marsupials have a pouch, or is it a female organ only (like the womb)? In most marsupials, only the females have a pouch. However, males of the water opossum and the extinct tasmanian tiger (or thylacine) also have a pouch. The males of both the thylacine and water opposum used/use their pouch to keep their genitalia from getting entangled in vegetation.
The following is multiple choice question (with options) to answer.
Females of what mammalian group have mammary glands but lack nipples? | [
"Metatheria",
"monotreme",
"prosauropod",
"Eutheria"
] | B | Monotreme eggs have a leathery shell, like the eggs of reptiles. The eggs are retained inside the mother’s body for at least a couple of weeks. During that time, the mother provides the eggs with nutrients. Platypus females lay their eggs in a burrow. Echidna females have a pouch in which they store their eggs. Female monotremes have mammary glands but lack nipples. Instead, they “sweat” milk from a patch on their belly. |
SciQ | SciQ-871 | bacteriology
Title: Extract bacteria from compost? I'm working on a project where I need to find certain cellulolytic bacteria. I was looking at this list : http://webcache.googleusercontent.com/search?q=cache:CrtQ9T6K7m8J:www.wzw.tum.de/mbiotec/cellmo.htm+&cd=1&hl=nl&ct=clnk&gl=be
How could I selectively separate one of the bacteria types that I had in mind from that list?
So how would I have to extract the bacteria from the compost? A first (and obvious) approach is the use of cellulose agar in order to isolate all the celluloltic bacteria in the sample. Be careful, however, since the nutrient requirements of some of those microbes may be higher and then they won't grow with only cellulose (they may need some other compounds, like a nitrogen source). Be careful with fungi, too.
If you have the proper equipment, it would be ideal to extract DNA and analyze the environmental rRNA 18s sequences. With this, you should be able to know if your bacteria is present in your sample. If so, proceed with the previous steps.
Once you had a set of suspected colonies, you must proceed with more specific culture media (wich would depend of the exact bacteria you're looking for. For example, if you're looking for Clostridium, you should try to grow your sample in an anaerobic jar and test the ability to reduce sulphur). With this approach, you may reach a point where you can't differenciate similar species. At this point, mollecular characterization is the best option, with the use of rRNA 18s again. Note that the mollecular approach, while relative expensive, can be performed in every step, so you can combine cultures and DNA analyses at will.
Lastly, if you're looking for an specific bacteria, it would be useful to know wich one is, so the community can give you more accurate responses.
The following is multiple choice question (with options) to answer.
What helps fungus digest cellulose and other materials found in rotting matter? | [
"soil",
"hormones",
"enzymes",
"carbohydrates"
] | C | Hyphae : These are thread-like strands which interconnect and bunch up into a mycelium ( Figure below ). Ever see mold on a damp wall or on old bread? The things that you are seeing are really mycelia. The hyphae and mycelia help the fungi absorb nutrients from other organisms. Most of the mycelium is hidden from view deep within the fungal food source, such as rotting matter in the soil, leaf litter, rotting wood, or dead animals. Fungi produce enzymes to digest cellulose and various other materials found in rotting matter, helping with the decaying process. |
SciQ | SciQ-872 | biochemistry, metabolism, bioenergetics
Title: What is the energy source for adipocytes? Since adipocytes export fatty acids and glycerol and don't use them as an energy source, what is the main source of energy for adipocytes? Adipocytes use glucose as an energy source. They express the insulin-responsive glucose transporter GLUT4 just like muscle cells so that when blood glucose levels rise they are primed to take the glucose up for fatty acid biosynthesis, but they also use glucose as a fuel molecule.
The following is multiple choice question (with options) to answer.
In what form of lipids cells store energy for long-term use? | [
"fat",
"meat",
"treasure",
"nuts"
] | A | Lipids Lipids include a diverse group of compounds that are united by a common feature. Lipids are hydrophobic (“waterfearing”), or insoluble in water, because they are nonpolar molecules. This is because they are hydrocarbons that include only nonpolar carbon-carbon or carbon-hydrogen bonds. Lipids perform many different functions in a cell. Cells store energy for long-term use in the form of lipids called fats. Lipids also provide insulation from the environment for plants and animals (Figure 2.17). For example, they help keep aquatic birds and mammals dry because of their water-repelling nature. Lipids are also the building blocks of many hormones and are an important constituent of the plasma membrane. Lipids include fats, oils, waxes, phospholipids, and steroids. |
SciQ | SciQ-873 | biochemistry, pathology, teeth, decay, minerals
Title: How does fluoride prevent tooth decay? Fluoride is a common active ingredient in tooth paste to prevent dental caries. It is also added or removed from the water supply in some communities for the same reason, but in children only.
My understanding is that the fluoride in tooth paste reacts with minerals in saliva then bonds to the tooth enamel. The fluoride in water is ingested and is somehow added to the developing bones and teeth of growing children, to the benefit of making decay resistant teeth.
What is the biochemical pathway of each process? A perfect answer will also discuss fluorosis and when that occurs and why. Your understanding is correct to some extent. Tooth enamel mostly consists of a mineral called hydroxyapatite ($\ce{Ca_{10}(PO4)6(OH)2}$) (Staines et al, 1981). Though this makes enamel the strongest material in the body, it is susceptible to degradation. In acidic environment, hyrdoxyapatite gets dissolved and leads to cavities (Brown, p. 688). The reaction is:
$\ce{Ca_{10}(PO4)6(OH)2_{(s)}~+~8~H+_{(aq)} -> 10~Ca^{2+}_{(aq)}~+~6~HPO4^{2-}_{(aq)}~+~2~H2O_{(l)}}$
To overcome this, fluoride is added in toothpastes. Fluoride ($\ce{F-}$) reacts with hydroxyapatite of enamel to form fluoroapatite via demineralization and remineralization cycle. The 3 main mechanisms through which it happens are (Rošin-Grget et al, 2013):
Iso-ionic exchange of $\ce{F-}$ for $\ce{OH-}$ in apatite:
$\ce{Ca_{10}(PO4)6(OH)2~+~2~F- -> Ca_{10}(PO4)6F2~+~2~OH-}$
The following is multiple choice question (with options) to answer.
What is used to fluoridate drinking water to promote dental health | [
"carbon fluoride",
"calcium fluoride",
"calcium fluorine",
"carbon fluorine"
] | B | Calcium fluoride is used to fluoridate drinking water to promote dental health. Crystalline CaF 2 (d = 3.1805 3. |
SciQ | SciQ-874 | thermodynamics, photochemistry
Title: Are photolysis reactions considered exothermic or endothermic? I know that photolysis is when a chemical reaction (usually decomposition) is forced by photons. I also note that there is a general warming in the stratosphere, due to the photolysis of ozone $$\ce{O_3 + $h\nu$ -> O + O_2}$$ and the subsequent restorative mechanism $$\ce{O + O_2 + M ->O_3 + M}$$ where $\ce{M}$ is a third body used to carry off excess energy. To me, that says that the photolysis of ozone is an endothermic reaction, and the reformation of ozone is an exothermic reaction, as the free body takes away excess energy (assumably thermal energy).
Am I correct in generalizing that photolysis is generally an endothermic reaction? If so, could the enthalpy released by the second equation be quantified by the frequency of the photon? In general it could be either. In your example you will have to work out the heat of formation of ozone and of O atoms (presumably it is an endothermic reaction). In general what the photon is doing is providing a way to overcome an activation barrier in the ground state by opening up a pathway from an excited state to the products. This last step is generally exothermic.
The enthalpy released in the second reaction is less than the photon energy by the difference in energy of the photon and that of products, an oxygen atom in your case as the heat of formation of O$_2$ is zero.
The sketch gives the general idea, I hope, for an endothermic reaction :)
Notes: The barriers may also be called transition states. There may be no barrier in the excited state. The crossing from the excited state potential to the product may be controlled by Landau-Zener behaviour or be a conical intersection. The far right upper line (not labelled) is the potential of the excited state of the product
The following is multiple choice question (with options) to answer.
Light reactions also release oxygen gas as a what? | [
"detritus product",
"strange process",
"waste product",
"formal process"
] | C | The light reactions also release oxygen gas as a waste product. |
SciQ | SciQ-875 | inorganic-chemistry, acid-base, everyday-chemistry
$$\ce{H2O + CO2(aq) <=> H2CO3}$$
and the protolysis of true $\ce{H2CO3}$
$$\ce{H2CO3 <=> H+ + HCO3-}$$
For a weak acid
$$\begin{align}
\log[\ce{H+}]&\approx\frac12\left(\log K_\mathrm a+\log[\ce{H2CO3^*}]\right)\\
&=\frac12\left(-6.3-5.0\right)\\
&=-5.65\\
\mathrm{pH}&=5.65
\end{align}$$
Thus, pure rain in equilibrium with the atmosphere has about $\mathrm{pH}=5.65$. Any acid rain with lower $\mathrm{pH}$ would be caused by additional acids.
The following is multiple choice question (with options) to answer.
What is the term for rain that has a ph less than 5, due to carbon dioxide dissolving? | [
"acid rain",
"frozen rain",
"basic rain",
"carbon rain"
] | A | Acid rain is rain that has a pH less than 5 (see Figure below ). The pH of normal rain is 5.6. It’s slightly acidic because carbon dioxide in the air dissolves in rain. This forms carbonic acid, a weak acid. |
SciQ | SciQ-876 | thermodynamics, physical-chemistry, chemical-potential, combustion
Title: How to thermodynamically understand process of burning a piece of coal? Let's imagine that I have a match in hand and nugget of coal on my desk. Then I light up the match and place it for few seconds near the coal so a tiny piece of nugget catches fire.
Then another piece catches fire, then another and soon all the nugget is burnt down.
How did it happen? I gave the nugget just enough heat to burn the first piece. Where does come energy to burn the rest of nugget from? It is called combustion, and it happens in materials which have a lower energy content when their component molecules join with the oxygen in the atmosphere, than when in a solid/liquid structure. When energy is given to start the fire the piece of coal burns and releases energy with excess enough to sustain the reaction and leave heat energy for use.
Combustion is a high-temperature exothermic chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.
The following is multiple choice question (with options) to answer.
What gas is released into the atmosphere when fossil fuels are burned? | [
"hydrogen",
"glucose",
"helium",
"co2"
] | D | Carbon dioxide levels in the atmosphere are increasing. Fossil fuel burning is increasing. The rise in fossil fuel burning is increasing the CO 2 in the atmosphere. |
SciQ | SciQ-877 | dna, radiation
Title: How do electrons destroy DNA bonds in radiation? Malignant tumors can be treated by radiation therapy. Most commonly it's radiotherapy with photons, or protons and so on. The common denominator for both types is that the radiation creates electrons inside the body via different effects.
What I haven't quite understood is how these electrons destroy the DNA bonds in the tumor and how this aids in killing off the cancer cells? Is it due to the generation of heat, or otherwise? I think you have a fundamental misunderstanding of the chemical reactions involved in radiation therapy. Neither photon based or proton based therapies "create electrons", but they do cause ionization by adding enough energy to existing electrons around atoms so that the electron is ejected from the atom, creating an ion or free radical, which can then undergo chemical reaction.
Photons, typically gamma rays, X-rays, and high energy UV, typically interact with water molecules and produce free radicals, including the dangerous hydroxyl radical. The hydroxyl radical can interact with proteins and DNA and damage those molecules, but has a very short half-life. Molecular oxygen can help increase the damage by reacting with the hydroxyl radical to produce Reactive Oxygen Species, ROS, which can also damage DNA or protein. However, many tumors have low oxygen concentration that reduces the effectiveness of photon based radiation therapy.
To overcome this, many patients receive proton based radiation therapy. Protons are much heavier than photons (I guess infinitely heavier than a photon, since photons have no mass) and therefore scatter to a much smaller extent. They just sort of plow through tissue and knock electrons out of orbitals as they collide with molecules such as DNA or protein. They don't rely so much on free radical generation or ROS, so low oxygen levels don't reduce their effectiveness.
The goal is damage the DNA to induce double strand breaks which are hard to repair in fast growing cancer cells. Because they grow so quickly, they are already stressed and their DNA repair machinery is less effective than in healthy cells. If their DNA can be sufficiently damaged, the cell will die.
For more information about these processes, please see these wikipedia articles on Radiation Therapy, Radiolysis, Linear Energy Transfer, and Free Radical Damage to DNA.
The following is multiple choice question (with options) to answer.
What are the most energetic of all electromagnetic waves, which can be used to treat cancer? | [
"gamma rays",
"infrared",
"ultraviolet",
"X-ray"
] | A | Gamma rays are the most energetic of all electromagnetic waves. They can pass through most materials, including bones and teeth. Nonetheless, even these waves are useful. For example, they can be used to treat cancer. A medical device sends gamma rays the site of the cancer, and the rays destroy the cancerous cells. If you want to learn more about gamma rays, watch the video at the URL below. |
SciQ | SciQ-878 | mass, weight
I used two socks, a binder clip to secure the weights to it, a pen, some string, and multiple 20 fl oz ( = 1.3 lbs of water ) bottles, and tried to see if the response was hookian over several bottles. I got
1 bottle -- 1.5 distance units
2 bottles -- 2.8 distance units
3 bottles -- 3.9 distance units
I'm being vague about the distance units because I didn't actually have a ruler handy, so instead used the L scale on my sliderule to measure the extensions
Rendered as a plot we see:
While this looks decent, I'm troubled by the fact that it doesn't line up well with the zero point extension of the sock, also we were only able to take 3 measurements since with the addition of the 4th bottle, the binder clip gave way.
Regardless of the questions of hookian reliability of the socks, to weigh your nephew at around 30 lbs, you would need something like 25 nearly identical socks, or calibrate all of them individually, and figure out a way to reliably afix your nephew to the socks. Due to the impracticality of the method, I can't recommend this approach, though in the interest of science, and so that others need not follow in my footsteps, I've shared this failure here.
The following is multiple choice question (with options) to answer.
When does a baby double in length and triple in weight? | [
"fetal stage",
"terrible twos",
"infancy",
"pre-adolescence"
] | C | Scientific notation is a way of writing very large or very small numbers that uses exponents. Numbers are written in the format a × 10 b . |
SciQ | SciQ-879 | homework, cell-membrane, human-physiology, lungs
Title: How many cell membranes are oxygen and carbon dioxide diffuse through in the lungs? In the lungs, oxygen and carbon dioxide pass through cell membranes by diffusion.
Which row is correct?
The correct answer is D, but I think it should be B. I can only think about three layers as maximum which are; epithelium of alveolus, endothelium of capillaries and the membrane of red blood cell. I don't know what are remainings.
Any help would be much appreciated! Oxigen goes from the alveolar's lumen to the cytoplasm of the erythrocyte, and that's 5 membranes:
the "top" of the alveolar epithelial cell
the "bottom" of such cell
the "top" of the endothelial cell (capillary)
the "bottom" of such cell
the erythrocyte membrane
You got all the cells right, but your only problem was this: oxygen diffuses through the cell membrane entering the cell, moves through the cytoplasm, and diffuses through the membrane again exiting the cell. So, for each cell, you have to count 2 membranes. For the last one, the erythrocyte, you have only 1 membrane (because it is $\ce{O2}$ final destination).
For the $\ce{CO2}$ the situation is a little bit more tricky. We have the same 4 membranes (2x epithelial cell and 2x capillary), but $\ce{CO2}$ can come from 2 locations:
from the erythrocyte, where it is formed from $\ce{H2CO3}$ (by the reaction $\ce{H2CO3 -> H2O + CO2}$) or released from the N-terminal group of proteins, like haemoglobin (where it has previously bound)
from the plasma (around 9% of the $\ce{CO2}$).
In the first case we have 5 membranes, and in the second case just 4.
So, the correct answer is D.
The following is multiple choice question (with options) to answer.
Where do the cells in your body get oxygen from? | [
"red blood cells",
"white blood cells",
"the digestive system",
"pores"
] | A | All the cells of your body need oxygen, which they get from red blood cells. Red blood cells, in turn, get oxygen in the lungs. The lungs are the main organs of the respiratory system. The respiratory system is the body system that exchanges gases with the outside air. It brings air containing oxygen into the body for the cells. It also releases carbon dioxide from the cells into the air. |
SciQ | SciQ-880 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
What type of generations do plants alternate between during a life cycle? | [
"haploid and clump",
"algal and diploid",
"vitro and diploid",
"haploid and diploid"
] | D | All plants have a life cycle that alternates between haploid and diploid generations. Plants vary in terms of which generation is dominant. Most modern plants have a dominant diploid generation. |
SciQ | SciQ-881 | evolution, natural-selection, mutations, sexual-reproduction
Four connected questions:
Is the mutation rate in male germline higher than in female germline?
If Yes, then doesn't this mean that Males are more likely the source of most beneficial genetic mutations, which is the main drive for evolution?
If 1 and 2 are true, then are we justified in inferring that "being the main source of beneficial genetic mutations" is the main purpose behind evolution of a Male sex?
Was this idea proposed before? If I actually understand your premises, which is a big if, you're asking if the genetic material in the sperm has been subjected to more mutation than its counterpart in the egg... by the time of mating. In case of humans, where's there's a lot of research and the answer is almost certainly yes.
Recent [GWAS] studies have shown that 76% of new mutations originate in the paternal lineage and provide unequivocal evidence for an increase in mutation with paternal age.
The general theory how this works (which you seem to repeat) goes back to...
Haldane (1947) suggested the following general mechanism for the sex differences in mutation rate: “The primordial oocytes are mostly if not all formed at birth, whereas spermatogonia go on dividing throughout the sexual life of a male. So if mutation is due to faulty copying of genes at a nuclear division, we might expect it to be commoner in males than females.”
As for [your] choice of terminology...
Subsequent estimates of a higher mutation rate in males from molecular genetic data led Miyata et al. (1987) to suggest that evolution is “male‐driven.”
And a more contemporary term is male-biased mutation:
The following is multiple choice question (with options) to answer.
Genetic diversity in a population comes from two main sources - sexual reproduction and what else? | [
"education",
"radiation",
"pathogen",
"mutation"
] | D | Variation and Adaptation Natural selection can only take place if there is variation, or differences, among individuals in a population. Importantly, these differences must have some genetic basis; otherwise, selection will not lead to change in the next generation. This is critical because variation among individuals can be caused by non-genetic reasons, such as an individual being taller because of better nutrition rather than different genes. Genetic diversity in a population comes from two main sources: mutation and sexual reproduction. Mutation, a change in DNA, is the ultimate source of new alleles or new genetic variation in any population. An individual that has a mutated gene might have a different trait than other individuals in the population. However, this is not always the case. A mutation can have one of three outcomes on the organisms’ appearance (or phenotype):. |
SciQ | SciQ-882 | states-of-matter, matter
Title: What distinguishes the difference states of matter from solid to BEC and perhaps fermionic condensate? Is it something to do with the behavior of electrons? How many states are there either discovered or predicted? 無
'States of matter' is a question of taxonomy, not of reality, and moreover, it's a result of the conditions surrounding the matter, not its internal properties. Certain combinations of properties give us a hint towards calling something 'solid' or 'liquid', but in truth there are no lines, just a continuous spectrum, and under certain conditions, matter transitions seamlessly through all sorts of states, both mundane and exotic:
Behold: Jupiter
A perfect example of this is Jupiter. Composed primarily of hydrogen, this gas giant consists (conjecturally) of a core of high-temperature hydrogen ice, floating in liquid hydrogen, enveloped in hydrogen gas, moving through interplanetary medium composed of hydrogen plasma.
Except not really: Under these conditions, the classical notions of states of matter break down entirely: Between these states of matter there are no interfaces, just a gradual, continuous transition.
In other words: The distinctive line to separate one state from another you are after doesn't really exist.
The following is multiple choice question (with options) to answer.
What state of matter completes the list: solid, liquid, gas? | [
"power",
"plasma",
"ice",
"energy"
] | B | A snowflake is made of ice, or water in the solid state. A solid is one of four well-known states of matter. The other three states are liquid, gas, and plasma. Compared with these other states of matter, solids have particles that are much more tightly packed together. The particles are held rigidly in place by all the other particles around them so they can’t slip past one another or move apart. This gives solids a fixed shape and a fixed volume. |
SciQ | SciQ-883 | ## Ch112
The aorta carries blood away from the heart at a speed of about 39 cm/s and has a radius of approximately 1.0 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.072 cm/s, and the radius is about 6.2 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
• solve in the same approach...
The aorta carries blood away from the heart at a speed of about 44 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.071 cm/s, and the radius is about 6.4 x 10-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Solution:
The volume has to be the same, so:
44cm/s * 1.44pi cm^2 = 199.05 cm^3/s
so x(.071cm/s * pi*.00064^2) = 199.05cm^3/s
x = (44 * 1.44pi)/(.071 * pi * .00064^2) = 2.17869718 * 10^9 capillaries
• The aorta carries blood away from the heart at a speed of about 37 cm/s and has a radius of approximately 1.2 cm. The aorta branches eventually into a large number of tiny capillaries that distribute the blood to the various body organs. In a capillary, the blood speed is approximately 0.069 cm/s, and the radius is about 6.3 x 10^-4 cm. Treat the blood as an incompressible fluid, and use these data to determine the approximate number of capillaries in the human body.
Flow rate = Cross sectional area * speed
Blood flow from the aorta = (pi)(1.2)^2(37) = 167.38 cm^3/sec.
The following is multiple choice question (with options) to answer.
The heart, blood vessels, and blood make up which system in the body? | [
"pulminary",
"respiratory",
"digestive",
"cardiovascular"
] | D | The cardiovascular system is made up of the heart, the blood vessels, and the blood. |
SciQ | SciQ-884 | meteorology, weather-forecasting, rainfall, rain
Title: Is there a consensus on the "heaviness" of rain? As part of the home dashboard I am developing, I get information about incoming rain. It is given in mm/min.
Is there a consensus on the precipitation rate that is called "light rain", or "heavy rain"? (I would like, if this is possible, to use some standardized naming) The German Weather Service (Deutscher Wetterdienst, DWD) provides the following definitions:
Heavy rain is defined as large amounts of precipitation during a fixed period of time. [...]
The DWD issues warnings of heavy rain using three categories:
heavy rain: 15 to 25 l/m² within 1 hour or 20 to 35 l/m² within 6 hours
severly heavy rain: 25 to 40 l/m² within 1 hour or 35 to 60 l/m² within 6 hour
extremely heavy rain: above 40 l/m² within 1 hour or above 60 l/m² within 6 hour
Source: https://www.dwd.de/DE/service/lexikon/begriffe/S/Starkregen.html and https://www.dwd.de/DE/wetter/warnungen_aktuell/kriterien/warnkriterien.html?nn=508722#doc453962bodyText3, translation my own.
Heavy rain is distinct from constant rain by the period of time, over which the rain falls, as well as the total amount of rain per m². Still, heavy rain events may be part of constant rain periods.
The following is multiple choice question (with options) to answer.
What unit of measurement is typically used for rainfall? | [
"pounds",
"gallons",
"inches",
"feet"
] | C | |
SciQ | SciQ-885 | star, galaxy, history, definition, stellar-structure
Title: Metallicity of Celestial Objects: Why "Metal = Non-metal"? Metallicity of objects refers to the amount of chemical elements present in it other than Hydrogen and Helium.
Note: The other elements may or may not be actual metals in the true sense of their defintion.
The following is multiple choice question (with options) to answer.
Which elements fall between metals and nonmetals in the periodic table? | [
"synthetics",
"halogens",
"noble gases",
"metalloids"
] | D | Metalloids are elements that fall between metals and nonmetals in the periodic table. Just seven elements are metalloids, so they are the smallest class of elements. In Figure above , they are color-coded orange. Examples of metalloids include boron (B), silicon (Si), and germanium (Ge). |
SciQ | SciQ-886 | physiology, muscles
Title: Does muscle get bigger by increase in size of individual cells or increase in number? Somewhere in the back of my mind, I have the claim that a muscle never increases its amount of cells but, if the muscle gets bigger, it's simply because individual cells get bigger.
The book Anatomy Trains on page 36 cites "Changes in sarcomere length and physiological properties in immobilized muscle by Williams et al" when it makes the claim :
Stretched, a muscle will attempt to recoil back to its
resting length before giving up and adding more cells
and sarcomeres to bridge the gap.
Is that true? Do muscles increase the number of their cells in that way? The "back of your mind" is correct: "if the muscle gets bigger, it's simply because individual cells get bigger."
Growth of muscle can occur in three ways:
by an increase in muscle cell numbers
by an increase in muscle fiber diameter
by an increase in fiber length.
However, growth in cell numbers is limited to the prenatal and immediately postnatal period, with the animals and man being born with or soon reaching their full complement of muscle cells.
[G]rowth occurs by either hypertrophy of the existing muscle fibers by adding additional myofibrils to increase the muscle mass or by adding new sarcomeres to the ends of the existing muscle fibers to increase their length. Both of these mechanisms occur during the growth process. Growth in the girth of the muscle fibers... may be stimulated by development of stress creating an unequal pressure with splitting at the Z-band and development of additional SR and T-tubule systems. This adds to the diameter or girth of myofibers without any hyperplasia. The growth in length occurs at either end of the fibers and results in addition of new sarcomeres. In both cases, new myofibrillar protein must be synthesized and deposited in the muscle cells.
The following is multiple choice question (with options) to answer.
What is it called when bones get longer and bigger? | [
"growth",
"expansion",
"reproduction",
"replication"
] | A | |
SciQ | SciQ-887 | biochemistry, physiology, muscles
Title: How is ATP involved in muscle contraction? The sliding filament mechanism as explained by my text does not elaborate on how ATP is involved in the cross bridge binding and contraction process. How does muscle contraction utilize ATP?
In my text explains this is the procedure for a contraction:
Ach released by motor neuron cross cleft and binds to motor end
plate
AP generated in response to binding of Ach gated channels and propagates down T tuble
T tuble triggers Ca2+ from sarcoplasmic reticulum
Ca2+ binds onto tropinin on actin filament and removes tropomyosin
This opens up sites for myosin to attach to actin using protein heads
Actin filament is pulled toward the center of sarcomere, causing contraction
I see that the action potential definitely needs ATP in order to be generated, aside from that I am surprised that the actual contraction via cross bridge binding does not seem to need ATP.
ATP prepares myosin for binding with actin by moving it to a
higher-energy state and a "cocked" position.
Once the myosin forms a cross-bridge with actin, the Pi disassociates
and the myosin undergoes the power stroke, reaching a lower energy
state when the sarcomere shortens.
ATP must bind to myosin to break the cross-bridge and enable the
myosin to rebind to actin at the next muscle contraction.
The following is multiple choice question (with options) to answer.
What kind of reactions are involved in processes ranging from the contraction of muscles to the digestion of food? | [
"atomical",
"mineral",
"chemical",
"liquid"
] | C | The rates at which chemical reactions take place in organisms are very important. Chemical reactions in organisms are involved in processes ranging from the contraction of muscles to the digestion of food. For example, when you wave goodbye, it requires repeated contractions of muscles in your arm over a period of a couple of seconds. A huge number of reactions must take place in that time, so each reaction cannot take longer than a few milliseconds. If the reactions took much longer, you might not finish waving until sometime next year. |
SciQ | SciQ-888 | mycology
Title: How do fairy rings propagate? It was somewhat new to me that mushrooms usually aren't individual organisms, but are merely the visible bodies of a bunch of fungi living in the soil. I know that mushrooms emit spores to reproduce, but what has been bizarre to me is how fairy rings form. Why do the fruiting bodies arrange themselves in a more or less circular shape, as opposed to the random scattering one would expect from wind-borne spores? When a fungal spore germinates in a suitable location, the growing mycelium will spread underground in all directions. In the ideal situation, the result is that the mycelium will become circular. Over time, the center of the mycelium will die out whereas the newly formed mycelium (underground) will develop the familiar mushrooms above ground and this will result in a fairy ring.
The following is multiple choice question (with options) to answer.
Mycorrhizae functions as a physical barrier to what? | [
"pathogens",
"vaccines",
"parasites",
"bacteria"
] | A | Mycorrhizae: The Symbiotic Relationship between Fungi and Roots A nutrient depletion zone can develop when there is rapid soil solution uptake, low nutrient concentration, low diffusion rate, or low soil moisture. These conditions are very common; therefore, most plants rely on fungi to facilitate the uptake of minerals from the soil. Fungi form symbiotic associations called mycorrhizae with plant roots, in which the fungi actually are integrated into the physical structure of the root. The fungi colonize the living root tissue during active plant growth. Through mycorrhization, the plant obtains mainly phosphate and other minerals, such as zinc and copper, from the soil. The fungus obtains nutrients, such as sugars, from the plant root (Figure 31.11). Mycorrhizae help increase the surface area of the plant root system because hyphae, which are narrow, can spread beyond the nutrient depletion zone. Hyphae can grow into small soil pores that allow access to phosphorus that would otherwise be unavailable to the plant. The beneficial effect on the plant is best observed in poor soils. The benefit to fungi is that they can obtain up to 20 percent of the total carbon accessed by plants. Mycorrhizae functions as a physical barrier to pathogens. It also provides an induction of generalized host defense mechanisms, and sometimes involves production of antibiotic compounds by the fungi. |
SciQ | SciQ-889 | human-biology, metabolism, muscles
The actual value of the (energy used by heart) / (energy used by skeletal muscles during exercise) depends on what exercise you do and how efficiently you do it. The change in the ratio between inactivity and activity depends on how much muscle mass you have (more muscle uses more energy during inactivity) and how strenuously you exercise. But the point is that the increased energetic demands by skeletal muscles far outpace the 3x increase in energetic demands by the heart and diaphragm - so the latter accounts for pretty much all total energy consumption at even moderate activity levels.
The following is multiple choice question (with options) to answer.
What do skeletal muscles enable the body to do? | [
"move",
"breathe",
"eat",
"look"
] | A | Skeletal Muscles. Skeletal muscles enable the body to move. |
SciQ | SciQ-890 | thermodynamics, equilibrium, entropy
Without the $^\circ$, concentrations could be anything. With the $^\circ$, concentrations are all at standard state, and $Q = 1$.
$\Delta S_{\text{total}}$[forward reaction] = $\Delta S_{\text{total}}$[backward reaction]
Point 2 is written in a way that confuses me. "Total" implies it covers everything that goes on, so separating it into forward and backward reaction is surprising. I asked the OP for the source of this statement in the comments. Maybe the context in the book would shed some light on the intention of the textbook author.
The following is multiple choice question (with options) to answer.
What is the sum total of all body reactions? | [
"respiration",
"growth",
"immunity",
"metabolism"
] | D | Water is an essential part of most metabolic processes within organisms. Metabolism is the sum total of all body reactions, including those that build up molecules ( anabolic reactions ) and those that break down molecules ( catabolic reactions ). In anabolic reactions, water is generally removed from small molecules in order to make larger molecules. In catabolic reactions, water is used to break bonds in larger molecules in order to make smaller molecules. |
SciQ | SciQ-891 | genetics
Additional response added as requested:
I see what you are getting at - why do children seem like such individual and unique things sometimes?
In sexual reproduction, the offspring are the product of the shuffling of the parent's genomes through meiosis, where the pairs of chromosomes we have are combined to make a single chromosome that will be half of the children genome.
This process can result in completely novel combinations of genes while conveying many likenesses from the parent. I would guesstimate that this is the major cause of the uniqueness of offspring/children.
Also in mammals there are some cell lines which splice families of genes which will cause offspring to be potentially quite different from either parent. Immune genes for instance are created from scratch from a bunch of genes that the parents give. Making each offspring unique but also the product of the parent's genetic repertoire. This can be significant as it affects health and also to some extent attraction - studies have shown that people who smell attractive to us are immunologically distinct from us.
@David mentions epigenetic variation, which is a more recent significant development. During our life, the germline (sperm/egg) DNA may be chemically labelled depending upon environmental conditions we experience. A famous example is experiencing famine conditions, which caused the children to be born on the small side amongst other effects. More recent studies have shown that this is a widespread mechanism to control cells in our body during our lifetime as well as communicate to our offspring how life is. It is expected that this labeling does not affect us forever - the epigenetic labels change over the course of a generation quite often (we believe).
The following is multiple choice question (with options) to answer.
What type of reproduction involves combining genetic material from two parents to create distinct offspring? | [
"sexual reproduction",
"asexual reproduction",
"mild reproduction",
"bsexual reproduction"
] | A | That is the main difference between sexual and asexual reproduction. Sexual reproduction is combining genetic material from two parents, usually from two gametes. How the two cells combine may take many forms, but does not necessarily involve physical contact. Sexual reproduction produces offspring that are genetically distinct from other offspring and from their parents. Asexual reproduction produces offspring from just one parent. These offspring are genetically identical to that one parent. |
SciQ | SciQ-892 | proteins, amino-acids, classification
Title: Classifying Polypeptides (and/or Proteins) Since polypeptides are a linear chain of twenty amino acids, each having a single letter abbreviation (e.g. Alanine = A). So can a polypeptide be represented as just the sequence (say: ADN for an Alanine, Aspartic acid, Asparagine polypeptide)?
This method of classifying polypeptides would lead to a possible 8000 (20**3) variations just for 3-amino-acid-polypetides (3200000 for 5-amino-acid-polypeptides, etc.) and that there would be many variations; and for longer polypeptides - that is, proteins - there would be even more variations.
Or are only the important polypeptides and proteins named, since not every variation of polypeptides and proteins are found in the body? I would've thought that many proteins (and enzymes, etc.) are incredibly specific and so they could be classified in some methodological way, as opposed to just 'lipase' or 'carbohydrase' which provides no structural information (though it would have a long methodological name). You can certainly refer to short peptides by their sequence. I don't know of any exact boundaries, but I've seen tripeptides referred to by either their three letter codes (Ala-Asp-Asn) or even the chemical name (alanylaspartylasparagine) although obviously that gets ridiculous pretty quickly.
As the largest known protein, titin also has the longest IUPAC name of
a protein. The full chemical name of the human canonical form of
titin, which starts methionyl... and ends ...isoleucine, contains
189,819 letters and is sometimes stated to be the longest word in the
English language, or any language. However, lexicographers regard generic names of chemical compounds as verbal formulae rather than English words
The following is multiple choice question (with options) to answer.
What kind of molecule is made from one or more long chains of amino acids? | [
"protein molecule",
"chain molecule",
"membrane molecule",
"amino molecule"
] | A | A protein molecule is made from one or more long chains of amino acids, each linked to its neighbors by covalent bonds. Multiple chains of a protein are held together by weaker bonds. |
SciQ | SciQ-893 | zoology, circulatory-system, heart-output, amphibians
I would add to this my notes from when I was a biochem student (but studied Zoology), mentioning the arterial cone and a spiral valve. This is better described in Britannica:
The conus arteriosus is muscular and contains a spiral valve. Again, as in lungfishes, this has an important role in directing blood into the correct arterial arches. In the frog, Rana, venous blood is driven into the right atrium of the heart by contraction of the sinus venosus, and it flows into the left atrium from the lungs. A wave of contraction then spreads over the whole atrium and drives blood into the ventricle, where blood from the two sources tends to remain separate. Separation is maintained in the spiral valve, and the result is similar to the situation in lungfishes. Blood from the body, entering the right atrium, tends to pass to the lungs and skin for oxygenation; that from the lungs, entering the left atrium, tends to go to the head. Some mixing does occur, and this blood tends to be directed by the spiral valve into the arterial arch leading to the body.
The following is multiple choice question (with options) to answer.
What part of the heart receives the blood is pumped from veins of the systemic circuit? | [
"right ventricle",
"right atrium",
"left atrium",
"left ventricle"
] | B | Figure 40.10 The mammalian circulatory system is divided into three circuits: the systemic circuit, the pulmonary circuit, and the coronary circuit. Blood is pumped from veins of the systemic circuit into the right atrium of the heart, then into the right ventricle. Blood then enters the pulmonary circuit, and is oxygenated by the lungs. From the pulmonary circuit, blood re-enters the heart through the left atrium. From the left ventricle, blood re-enters the systemic circuit through the aorta and is distributed to the rest of the body. The coronary circuit, which provides blood to the heart, is not shown. |
SciQ | SciQ-894 | physical-chemistry, phase
Title: Properties of plasmas In chemistry one can recognize that the four states of matter are solid, liquid, gas and plasma. The first is rigid, and has a definite shape and volume. The second doesn't have a shape, and assumes the shape of its container, but it has a fixed volume. The third doesn't have either a shape or a fixed volume and assumes the volume and shape of its container. What about the fourth one (plasma)? Plasma is made up of ionized gas, so molecules have a positive electric charge and valency electrons are totally or partially separated by their nuclei.
Plasma is different from a gas since it has a high temperature and is radiation emitting; think of the Sun and other stars, which are made up of plasma and show both these properties.
Plasma hasn't got a proper volume, like gases; e.g. stars can expand or contract under the opposite effects of gravity and nuclear fusion. For example, this property is important to comprehend the formation of white dwarfs and neutron stars, process caused by high pression due to gravity.
Little trivia: there is also a fifth state of matter, whose name is Bose-Einstein Condensate (BEC).
The following is multiple choice question (with options) to answer.
What type of properties are characteristics that describe matter? | [
"invisible",
"visible",
"physical",
"thermal"
] | C | The properties that chemists use to describe matter fall into two general categories. Physical properties are characteristics that describe matter. They include characteristics such as size, shape, color, and mass. Chemical properties are characteristics that describe how matter changes its chemical structure or composition. An example of a chemical property is flammability—a material’s ability to burn—because burning (also known as combustion) changes the chemical composition of a material. |
SciQ | SciQ-895 | human-biology, cancer, medicine
Title: Why are only few cigarette smokers prone to cancer? It's tacit that only a few populace of smokers get cancer. What spares the others from it or what specifically cause cancer in those populace? See this Washington Post Article Cigarette smokers are most certainly prone to cancer. See Cecil Medicine, Chapter 183, on the epidemiology of cancer, exposure to tobacco is the most important environmental risk factor for cancer development, at least in the US:
Exposure to tobacco is the single largest cause of cancer in the United States... All forms of tobacco can cause cancer. Cigarette smoking causes cancer of the lip, oral cavity, nasal cavity, paranasal sinuses, pharynx (nasal, oral, and hypopharnyx), larynx, lung, esophagus (squamous cell and adenocarcinoma), stomach, colorectum, pancreas, liver, kidney (adenocarcinoma and renal pelvis), urinary bladder, uterine cervix, and myeloid leukemia.
Cancer may be identified or the cause of death in fewer smokers than might be expected, though, because smoking is an even greater risk factor for cardiovascular disease, and death due to cardiovascular disease.
Cancer is an unlikely phenomenon in an individual cell, but becomes more likely at the organism level, and even more likely over time. Though tobacco may be the most important environmental risk factor for cancer, age is actually a stronger predictor of cancer (see again, Cecil Chapter 183. Autopsy studies give us a quite remarkable example, this one shows incidental prostate cancer in nearly 60% of men over 80 who died from other causes. That figure is not out of the ordinary. Live long enough and you are likely to develop cancer.
Death due to heart disease may account for the lower than expected rates of cancer diagnoses and deaths in smokers. Nothing prevents cancer as well as dying from something else. And as discussed in the blog in the Washington Post you linked to, up to 2/3 of smokers die from smoking related causes
The following is multiple choice question (with options) to answer.
What is the leading cause of death in the united states? | [
"automobile accidents",
"suicide",
"heart disease",
"lung cancer"
] | C | Cardiologist Heart disease is the leading cause of death in the United States. This is primarily due to our sedentary lifestyle and our high trans-fat diets. Heart failure is just one of many disabling heart conditions. Heart failure does not mean that the heart has stopped working. Rather, it means that the heart can’t pump with sufficient force to transport oxygenated blood to all the vital organs. Left untreated, heart failure can lead to kidney failure and failure of other organs. The wall of the heart is composed of cardiac muscle tissue. Heart failure occurs when the endoplasmic reticula of cardiac muscle cells do not function properly. As a result, an insufficient number of calcium ions are available to trigger a sufficient contractile force. Cardiologists (cardi- = “heart”; -ologist = “one who studies”) are doctors who specialize in treating heart diseases, including heart failure. Cardiologists can make a diagnosis of heart failure via physical examination, results from an electrocardiogram (ECG, a test that measures the electrical activity of the heart), a chest X-ray to see whether the heart is enlarged, and other tests. If heart failure is diagnosed, the cardiologist will typically prescribe appropriate medications and recommend a reduction in table salt intake and a supervised exercise program. |
SciQ | SciQ-896 | pressure
Title: Microscopic idea of sudden extreme pressure difference I'm having some issues understanding what's happening microscopic when there's sudden changes in the pressure.
The microscopic idea, is that particles randomly bounces around each other. It's even possible with entropy to state all the air can go to one side of the room, and leave a vacuum on the other side but off course very improbable.
But if particles just randomly just bounces around, why are you being sucked out of a space station, if the doors are suddenly opened into the vacuum? Why can the molecules around you feel the doors has been opened another place, if they just randomly bounces around? They are still just "randomly" bouncing around. The problem is that you've now changed the constraints for which they can randomly bounce.
Before, the odds that they could randomly bounce outside the ship are extremely limited. For the most part, bouncing is constrained to other particles and the walls of the ship itself. As soon as you introduce an easier pathway out of the ship, some of the gas will begin randomly bouncing out that hole. What's especially important is that once they start to move away, it's extremely unlikely that much of the air escaping will bounce back into the ship. Instead, they are free to start permeating space where they have very low chances of collisions that would send them back. This creates a net flow rate out of the hole compared to the essentially evenly distributed bouncing around when it is enclosed by walls and pressurized gases.
If you're facing the hole, collisions with gasses behind you are likely to send the air essentially backwards, hitting the air behind it, which cascades until it hits the wall and essentially pushes back on you. In front of you, when you push against the air, it collides with more air, which cascades; but there is no wall to push back against it, so the air just starts flowing out the hole.
The following is multiple choice question (with options) to answer.
What results when gas particles rebound off the walls of their container? | [
"pressure",
"light",
"pull",
"weight"
] | A | Pressure is what results when gas particles rebound off the walls of their container. The basic unit of pressure is the newton per square meter (N/m2). This combined unit is redefined as a pascal (Pa). One pascal is not a very large amount of pressure. A more useful unit of pressure is the bar, which is 100,000 Pa (1 bar = 100,000 Pa). Other common units of pressure are the atmosphere (atm), which was originally defined as the average pressure of Earth’s atmosphere at sea level; and mmHg (millimeters of mercury), which is the pressure generated by a column of mercury 1 mm high. The unit millimeters of mercury is also called a torr, named after the Italian scientist Evangelista Torricelli, who invented the barometer in the mid1600s. A more precise definition of atmosphere, in terms of torr, is that there are exactly 760 torr in 1 atm. A bar equals 1.01325 atm. Given all the relationships between these pressure units, the ability to convert from one pressure unit to another is a useful skill. |
SciQ | SciQ-897 | sexual-reproduction
So when it's not maintained -- when there's no selection pressure on two populations -- inevitably there will be genetic drift that will randomly disrupt this fine-tuned system. If a population of, say, voles is isolated on an island, they will continue to have pressure to be able to interbreed with other voles on the island, but if they can't interbreed with those on the mainland there won't be any consequences, and so over long enough time they'll drift and lose that ability -- just as many apes, not suffering any consequences from not synthesizing vitamin C, gradually lost that ability from random drift.
There's another side to it. Two populations in the same location may be positively selected to not be able to interbreed. Think about two groups of finches, one with small fine beaks that eat tiny seeds deep inside pine cones, and one with heavy beaks that crush and eat thick-shelled nuts. They each do fine, but they can interbreed and produce offspring that have intermediate beaks -- too thick to reach the fine seeds that one parent eats, but too delicate to crush the nuts that the other parent eats. Those intermediate offspring will die off, and both parents will have wasted their resources raising them. Both parents would be better off not breeding with each other, but only breeding with their own kind to produce specialized and efficient offspring. There is now selection pressure on the birds to recognize their own kind (perhaps through songs or mating displays) and ultimately to be inter-sterile, so they never waste resources on the un-fit offspring. There's a gradation of separation over time, in which the different populations become more and more distinct. Eventually, at some arbitrary point, humans start calling them "species", but that's just us, not biology.
"Species" is an important concept, but it's not special in evolution; speciation is just one aspect of natural selection, there's nothing magical about it.
The following is multiple choice question (with options) to answer.
How do most fish reproduce with one another? | [
"same sex",
"on land",
"sexually",
"asexually"
] | C | Fish reproduce sexually. They lay eggs that can be fertilized either inside or outside of the body. In most fish, the eggs develop outside of the mother's body. In the majority of these species, fertilization also takes place outside the mother's body. The male and female fish release their gametes into the surrounding water, where fertilization occurs. Female fish release very high numbers of eggs to increase the chances of fertilization. |
SciQ | SciQ-898 | thermodynamics, atoms, phase-transition
But let's look at how the states change. In a solid, you have a bunch of atoms that can be thought of as masses connected by springs. As heat is added to the system, the atoms begin to vibrate in the lattice of springs. As more heat is added, they vibrate enough to break the springs. This is when the solid begins to melt and turn to a liquid.
Now you have a liquid where the atoms are all moving around but they aren't free to move wherever they want. More heat is added to the system and the atoms begin to translate faster and faster. Eventually they translate fast enough to overcome the forces that are holding them together in a liquid. Now they fly free and are a gas.
So ultimately, heat is energy that makes atoms and molecules move in some way. They may translate, rotate, vibrate, or the electrons may begin moving around depending on how much heat is there and what configuration the molecule has.
The following is multiple choice question (with options) to answer.
What is the ability to cause changes in matter? | [
"hydrogen",
"energy",
"pressure",
"force"
] | B | Energy is the ability to cause changes in matter. For example, your body uses chemical energy when you lift your arm or take a step. In both cases, energy is used to move matter—you. Any matter that is moving has energy just because it’s moving. The energy of moving matter is called kinetic energy. Scientists think that the particles of all matter are in constant motion. In other words, the particles of matter have kinetic energy. The theory that all matter consists of constantly moving particles is called the kinetic theory of matter . You can learn more about the theory at this URL: http://www. youtube. com/watch?v=Agk7_D4-deY . |
SciQ | SciQ-899 | orbitals, atoms
Title: Why are atoms with eight electrons in the outer shell extremely stable? Atoms that have eight electrons in their outer shell are extremely stable. It can't be because both the $s$ and the $p$ orbitals are full, because then an atom with 13 or 18 valence electrons would be extremely stable. ($d$ has 10, and 5 is also stable).
Why is it that atoms with eight electrons in the outer shell are extremely stable? First, this isn't quite true. It is true for the first row of the periodic chart (from lithium to neon). It is almost true for the second row (from sodium to argon. But there are exceptions there. Beyond that it really isn't true at all for the elements beyond the first two columns.
The reason for the increased stability for the first two rows lies in quantum mechanics. Classically we can note that there are no $d$ electrons there. Another ways of looking at it from a classical point of view is that the early elements are too small to allow too many other atoms or groups of atoms around them. That tends to go away as you go down the periodic chart and the atoms get "fatter". A typical example is chloroplatinic acid which has six chlorines around it.
Most transition metals also can have more than four groups around them as well.
I suspect that this isn't an exceptionally useful explanation. As I said, the answer really lies in quantum mechanics. In looking up "molecular orbital theory", one reference can be found here.
The following is multiple choice question (with options) to answer.
The group 18 gases that have 8 valence electrons are referred to as what type of gases? | [
"important",
"novel",
"noble",
"metal"
] | C | A common way to keep track of valence electrons is with Lewis electron dot structures . In an electron dot structure, each atom is represented by its chemical symbol, and each valence electron is represented by a single dot. Note that only valence electrons are shown explicitly in these diagrams. For the main group elements, the number of valence electrons for a neutral atom can be determined by looking at which group the element belongs to. In the s block, Group 1 elements have one valence electron, while Group 2 elements have two valence electrons. In the p block, the number of valence electrons is equal to the group number minus ten. Group 13 elements have three valence electrons, Group 14 elements have four, and so on. The noble gases in Group 18 have eight valence electrons, and the full outer s and p sublevels are what give these elements their special stability. Representative dot diagrams are shown in the Figure below :. |
SciQ | SciQ-900 | biophysics, theoretical-biology, ecosystem
Systems ecology, especially with regard to energy and nutrient flow.
This type of ecology can be strongly influenced by physics. For one example see the book Theoretical Ecosystem Ecology: Understanding Element Cycles by Ågren & Bosatta (Ågren was originally a physicist)
Physical limitations to growth and transport
This can include for instance mechanical contraints on plant growth (see e.g. the book Plant Physics by Nicklas & Spatz), water transport in trees (see e.g. this BioSE question) or the biomechanics of movement (see e.g. Hudson et al (2012) on the speed and movement of cheetahs or Wikipedia: Biomechanics).
Allometric relationships between organisms, e.g. with regard to metabolism
To explain these types of relationships knowledge in physics is useful. See e.g. Kleiber's law for more.
MAXENT as a general approach to ecological patterns or to model species distributions
This is basically a tool lifted from physics that can be applied to ecological problems. There are many papers to look at, but Harte & Newman (2014) (Harte is another previous physicist) and Elith et al (2010) are two good starting points.
Dynamical modelling of populations and communities
This field use many of the same tools for analysis as physics, e.g. systems of differential equations. One of the pioneers in this field (among many) were Robert May (also started with a PhD in physics), and his classical book Theoretical Ecology: Principles and Applications is still a good starting point.
Energy harnessing and conversion by organisms
This can refer both to how organsims convert prey to energy (e.g. conversion efficiencies) and the physics of photosynthesis (which is an interesting intersection between physics and molecular biology). See Jang et al (2004) and O'Reilly & Olaya-Castro (2013) for examples of the how quantum mechanics can inform us about photosynthesis.
Hopefully this will give you a sense of some different ways that knowledge in physics can be useful for biology.
The following is multiple choice question (with options) to answer.
Competition is a relationship between organisms that depend on the same resources. the resources might be food, water, or what? | [
"time",
"language",
"thought",
"space"
] | D | Competition is a relationship between organisms that depend on the same resources. The resources might be food, water, or space. Competition can occur between organisms of the same species or between organisms of different species. |
SciQ | SciQ-901 | human-biology, digestive-system, immune-system, microbiome
The next level of defense comes from the cells of the innate immune system (14). In innate immunity, specialized cells monitor the area they are in for Pathogen-Associated Molecular Patterns (PAMPs). PAMPs can be sugars that make up the cell walls of the microbe or proteins that get expressed on the surface of the organism, such as Flagellin, a protein only found in the flagella of certain pathogen. The innate immune cells have pattern recognition receptors (PRR) that have a general specificity for recognizing and responding to the PAMPs. Our cells even have PRRs for DNA and Double Stranded RNA's, however those are usually found in vesicles on the inside of the cell. These interactions are very general, however once PRRs bind to the PAMP, they are able to signal into the cytoplasm, which can lead to the production of proteins, among other possible responses.
Here you can think of PRRs like a motion detector in a security system; the dog, or your two year old, or an intruder are going to set off the alarm just the same. It is not specific. The motion sensor "knows" that something that it is supposed to recognize, i.e. a moving object larger than a mouse passed by and it triggered the response, but it cannot tell you which moving object triggered it, only that it was triggered.
The innate immune cells are also able to respond by "eating" the pathogen in a process called phagocytosis. Here, they break up the bacteria, yeast, or the remnants of other dead host cells or large pathogens, things like worms, and put the broken up pieces on protein molecules on their surface.
When innate immune cells do this, they are presenting molecules to specialized immune cells (adaptive immune cells (14)), B-Cells and T-Cells, that are highly specific as to what they will react to. These cells can also cause a lot of damage to the host, so they are tightly regulated. Think of the interactions as keys and locks. A protein from a bacteria should turn a few of these cells on, but a protein from the host should not fit the lock.
The following is multiple choice question (with options) to answer.
What does phagocytosis defend the body from? | [
"parasites",
"allergies",
"pathogens",
"obesity"
] | C | 4. State how phagocytosis helps defend the body from pathogens. |
SciQ | SciQ-902 | mobile-robot, sensors, raspberry-pi, uav
Title: How to measure pull force on a (kite) rope? I'm building a kite flying robot, in which I've already got some sensors built in. I now also want to measure the pulling force on the rope which is attached to the kite. So I thought of attaching a hanging digital scale to the rope which can then measure the pulling force in kilograms. I of course need to read out the data from the scale using GPIO pins or USB.
Furthermore, I also have a raspberry pi installed within the kite and I want to measure some pull on ropes in the air. So if possible, I also need very small/light scales from which I can read out the data. It would be great if the scales can measure up to about 50kg, but with some pulleys about 20kg would be fine as well.
Unfortunately I can't find any digital hanging scale with a possibility to read out the data and which is reasonably light. There are some simple USB powered hanging scales, but I think they just use USB for charging, not for reading out data. And I also found this one, but that's a bit overkill (too heavy and too expensive).
So question #1: Does anybody know where I can get a simple existing hanging scale from which I can read out data?
If needed I can also build something, but I just wouldn't know where to start. I did find this page on Alibaba, where they show the contents of the scale they offer:
The following is multiple choice question (with options) to answer.
What measures the force of gravity pulling on an object? | [
"weight",
"volume",
"velocity",
"density"
] | A | Weight measures the force of gravity pulling on an object. The SI unit for weight is the Newton (N). |
SciQ | SciQ-903 | palaeontology, herpetology
Title: How big can cold-blooded animals get? It seems impossible to have reptiles the size of dinosaurs, just because they are really big! Did they have different systems of maintaining body temperature or maybe they weren't the exact type of animals that we today call reptiles? Answer is quite simple as from @Alan Boyd link. They are cold blooded and thus, can go out for hunt in cold, they need to stay put till they get some prey.
So, it mainly depend on the temperature of the outside, I found this interesting paper on relation of body sizes and latitude.
Body sizes of poikilotherm vertebrates at different latitudes
Maximum sizes of 12,503 species of poikilotherm vertebrates were
analyzed for latitudinal trends, using published data from 75 faunal
studies. A general trend appears which may be summarized by the rule
"among fish and amphibian faunas the proportion of species with large
adult size tends to increase from the equator towards the poles". The
rule holds for freshwater fish, deepsea fish, anurans, urodeles, and
marine neritic fish arranged roughly in order of decreasing clarity of
the trend). In general the rule applies not only within these groups
of families but also within single families. In reptile groups, the
rule holds weakly among snakes and not at all among lizards or
non-marine turtles. Possible explanations include an association
between small size and greater specialization in the tropics; the
possibility in poikilo-therms of heat conservation or of some other
physiological process related to surface/volume ratio; selection for
larger size in regions subject to winter food shortages; and an
association between large adult size and high reproductive potential
in cold regions. Other suggestions can be advanced, but all are
conjectural and few are subject to test. Global size - latitude trends
should be looked for in other living groups.
Cite: Lindsey, C. C., 1966: Body sizes of poikilotherm vertebrates at
different latitudes. Evolution: 456-465
Now lets compare some of the largest cold blooded Animals:
Reptiles
Amphibians
Fishes (Pisces)
The following is multiple choice question (with options) to answer.
Are coral reefs found in warm or cold water? | [
"warm",
"cold",
"both",
"cool"
] | A | Coral reefs are found only in warm water. Coal swamps are also found in tropical and subtropical environments. Wegener discovered ancient coal seams and coral reef fossils in areas that are much too cold today. Wegener thought that the continents have moved since the time of Pangaea. |
SciQ | SciQ-904 | If the papillae (bumps on your tongue) can sense 5 basic tastes
and any combination of those tastes produce a unique taste,
how many possible unique tastes can you have?
. . $\displaystyle \begin{array}{ccccc} \text{1-at-a-time:} & _5C_1 &=& 5 \\ \text{2-at-a-time:} & _5C_2 &=& 10 \\ \text{3-at-a-time:} & _5C_3 &=& 10 \\ \text{4-at-a-time:} & _5C_4 &=& 5 \\ \text{5-at-a-time:} & _5C_5 &=& 1 \\ \hline & \text{Total:} && {\color{blue}31} \end{array}$
Call the five basic tastes: $\displaystyle a,b,c,d,e$
You can list them and count them yourself . . .
. . $\displaystyle \begin{array}{ccc}\text{1-at-a-time:} & a,b,c,d,e \\ \\ \text{2-at-a-time:} & ab,ac,ad,ae,bc\\ & bd,be,cd, ce, de \\ \\ \text{3-at-a-time:} & abc, abd, abe, acd, ace \\ & ade, bcd, bce, bde, cde \\ \\ \text{4-at-a-time:} & abcd, abce, abde, acde, bcde \\ \\ \text{5-at-a-time:} & abcde \end{array}$
6. Originally Posted by Soroban
Hello, Masterthief1324!
I agree with skeeter and Dinkydoe . . .
The following is multiple choice question (with options) to answer.
In humans, there are five primary tastes, and each taste has only one corresponding type of what? | [
"neuron",
"receptor",
"organ",
"membrane"
] | B | In humans, there are five primary tastes, and each taste has only one corresponding type of receptor. Thus, like olfaction, each receptor is specific to its stimulus (tastant). Transduction of the five tastes happens through different mechanisms that reflect the molecular composition of the tastant. A salty tastant (containing NaCl) provides the sodium ions (Na+) that enter the taste neurons and excite them directly. Sour tastants are acids and belong to the thermoreceptor protein family. Binding of an acid or other sour-tasting molecule triggers a change in the ion channel and these increase hydrogen ion (H+). |
SciQ | SciQ-905 | thermodynamics, equilibrium, free-energy
ultimately we'll have ∆G to be a large, negative value which makes the reaction spontaneous?
you can calculate a negative $\Delta G{_r}$ for the reaction when you have no (or infinitesimal amounts of) products.
Many texts are moving away from the term "spontaneous" for this situation, because the system may not shift to the right (reactants convert to products) if there is a kinetic barrier to prevent this, so the forward reaction may not actually be observed. The term "thermodynamically favored" is often used instead, meaning having a negative $\Delta G{_r}$ under these conditions.
You can find lots more about these concepts at the following posts:
If change in free energy (G) is positive, how do those reactions still occur?
Calculating ΔG at the extremes of reaction extent
The following is multiple choice question (with options) to answer.
The large positive free energy change leads to a value that is extremely what? | [
"small",
"high",
"complex",
"random"
] | A | The large positive free energy change leads to a value that is extremely small. Both lead to the conclusion that the reactants are highly favored and very few product molecules are present at equilibrium. |
SciQ | SciQ-906 | growth
Title: Do slime mold expand or multiply? After reading about slime mold I was wondering, do slime mold simply expand outwards or multiply?
e.g. if I put 100 grams of slime mold in 1 location, will it expand to say, 2 locations, and have the 1st location with 80 grams left, and 2nd location with 20 grams (i.e total 100 grams), or is it that they multiply; 1st location still 100 grams, and 2nd location with 20 grams? The answer is that they will do either or both, depending on conditions: this is one of the things that has caused complex systems scientists to be so interested in things like using slime molds in modeling optimization problems.
In good nutritional conditions, the cells will happily multiply. At the same time, they will flow and reshape themselves to spread and migrate in search of food when nutrients are not uniform.
The following is multiple choice question (with options) to answer.
Slime molds are fungus-like protists that grow as slimy masses on what? | [
"dark matter",
"recycled matter",
"food matter",
"decaying matter"
] | D | Slime molds are fungus-like protists that grow as slimy masses on decaying matter. They are commonly found on items such as rotting logs. |
SciQ | SciQ-907 | zoology, marsupials
Title: Do male marsupials have a pouch? Do male marsupials have a pouch, or is it a female organ only (like the womb)? In most marsupials, only the females have a pouch. However, males of the water opossum and the extinct tasmanian tiger (or thylacine) also have a pouch. The males of both the thylacine and water opposum used/use their pouch to keep their genitalia from getting entangled in vegetation.
The following is multiple choice question (with options) to answer.
What is the body cavity that reptiles have that is involved in reproduction? | [
"ovules",
"hypothalamus",
"pristil",
"cloaca"
] | D | Most reptiles have sexual reproduction with internal fertilization. Reptiles have a body cavity called a cloaca that is involved in reproduction. Sperm or eggs are released into an adult reptile’s cloaca. Males have one or two penises that pass sperm from their cloaca to the eggs in the cloaca of a female, where fertilization takes place. In most reptile species, once fertilized the eggs leave the body through an opening in the cloaca. These reptiles are oviparous. Eggs develop and hatch outside the mother’s body. |
SciQ | SciQ-908 | organic-chemistry, reaction-mechanism, molecular-structure, structural-formula
Title: Nucleophile in a reaction How can we determine which atom is a nucleophile in a compound in a reaction?
I know we see resonance, but I am little confused between electronegativity, formal charge, solvent, and size. Here are some rules i remember from organic chemistry in Collage.
When trying to distinguish between nucleophile and base,
Look for resonance
If atom is involved in resonsance, this makes ato/group more nucleophilic,
if electrons are more localized its more basic.
Eg. A carboxylate is a nucleophile, the -ve charge is delocalized (i.e - charge is spread out across carbonyl and oxyanion. Compared to nitrogen on an amine, electron are restricted.
Sterics,
more sterics less nucleophilic.
Smaller radius atoms, valence electrons are more localized in space, thus more basic. Big radius atoms, poor localization relative to small, thus more nucleophilic.
More electronegastive, less basic
Electronegativity is a measure of the nuclear positive charge effect on near -ve charges.
The more electronegative the less basic. Because the atom doesnt want to give up its electrons. Why? Because it has high electronegativity
Conduction effects
If there are electronegative atoms within 3 bonds (taking into account electronegativities, and proximity) more nucleophilic less basic.
Nitrogens are usually bases, oxygens nucleophiles. I swear it was always like that. Halogens are weak nucleophiles.
Will edit for legibility when i get to computer
The following is multiple choice question (with options) to answer.
What is the germ for a group of atoms within a molecule that reacts similarly anywhere it appears in different compounds? | [
"molecular group",
"functional group",
"thermal group",
"atomic group"
] | B | With over twenty million known organic compounds in existence, it would be very challenging to memorize chemical reactions for each one. Fortunately, molecules with similar functional groups tend to undergo similar reactions. A functional group is defined as an atom or group of atoms within a molecule that has similar chemical properties whenever it appears in various compounds. Even if other parts of the molecule are quite different, certain functional groups tend to react in certain ways. |
SciQ | SciQ-909 | biochemistry, physiology, cell-biology
Title: What triggers meiosis in gonadal cells? What specific biochemical processes are involved in inducing meiosis rather than mitosis? Why are gonadal cells the only cells in the human body which do undergo meiosis?
What specific biochemical processes are involved in inducing meiosis rather than mitosis?
It's a difficult question because every step in the development of a germ cell is ultimately necessary for the final differentiation, which includes a meiotic division. Meiosis requires a lot of specialized components to pair and segregate homologues, to induce and resolve recombination, etc. What starts it all is still largely unknown. There are plenty of mutants that halt the process, but these are required along the way, so damaging the pathway ultimately stops it from progressing. At least one study has been able to initiate the program of meiosis in yeast:
Induction of meiosis in Saccharomyces cerevisiae depends on conversion of the transcriptional represssor Ume6 to a positive regulator by its regulated association with the transcriptional activator Ime1. I Rubin-Bejerano, S Mandel, K Robzyk, and Y Kassir
Basically, they turned on a transcription factor, which activated an entire suite of downstream genes necessary for meiosis. In essence, they turned on the "meiosis pathway." Bear in mind this is yeast, so does't have separate germ cells, but the concept is probably the same.
Why are gonadal cells the only cells in the human body which do undergo meiosis?
All other cells are diploid. Only in germ cells does the organism induce reductional divisions (to make haploid gametes for ultimate fusion in the zygote of the next generation). Creation of haploid somatic cells would uncover recessive lethal mutations and cells would die. In sperm and eggs, which do not express any genes until after fertilization and karyogamy, this is not a problem.
The following is multiple choice question (with options) to answer.
During asexual reproduction, fungi produce haploid spores by what process involving a haploid parent cell? | [
"mitosis",
"evaporation",
"divergence",
"osmosis"
] | A | During asexual reproduction, fungi produce haploid spores by mitosis of a haploid parent cell. A haploid cell has just one of each pair of chromosomes. The haploid spores are genetically identical to the parent cell. Spores may be spread by moving water, wind, or other organisms. Wherever the spores land, they will develop into new hyphae only when conditions are suitable for growth. |
SciQ | SciQ-910 | evolution, biochemistry, mitochondria
Title: Is there any advantage of having mitochondria for aerobic respiration? If we consider the pathway of breakdown of glucose which includes glycolysis, the citric acid cycle and the electron transport chain, all these processes takes place in some prokaryotes and eukaryotes. In prokaryotes all these processes take place in cytoplasm while in eukaryotes the last two processes take place in mitochondria.
So is there any advantage of performing the last two processes in the mitochondria? Does it yield more energy? If there is no advantage, what is the point of having a mitochondria (at least for this process)? From the evolutionary point of view, the eukaryotes acquired these metabolisms (except glycolysis) from their prokaryotic endosymbionts. Not all prokaryotes have the ETC. The free living ancestor of mitohondria is supposed to be the alpha-proteobacterium.
Now, glycolysis is a common pathway in lot of lifeforms perhaps because of abundance of glucose. TCA cycle is coupled with ETC at certain steps which makes it essentially a part of aerobic metabolism.
The reason for having a dedicated organelle for respiration
ATP synthesis is a membrane process. Imagine a large prokaryotic cell- as big as an animal cell. Such a cell cannot take care of its energetic demands which primarily consists of protein synthesis with the given area of membrane i.e it needs much more ATP-synthases than it can have to cope up with the energy demands of maintaining such a huge cell (this index is approximated based on surface to volume ratio). Therefore it is wise to harbor multiple efficient organelles i.e. mitochondria which themselves have just a small essential genome and proteome to maintain.
For a better understanding, please read this article. I just loved it.
There is also a book by the same author about mitochondria called Power, Sex, Suicide.
The following is multiple choice question (with options) to answer.
In eukaryotes, oxidative phosphorylation takes place in what? | [
"lipids",
"glucose",
"mitochondria",
"nucleus"
] | C | Figure 7.5 In eukaryotes, oxidative phosphorylation takes place in mitochondria. In prokaryotes, this process takes place in the plasma membrane. (Credit: modification of work by Mariana Ruiz Villareal). |
SciQ | SciQ-911 | nutrition, hematology, metabolism
Title: How does a glucose molecule enter the cell from blood vessel? The transporters in the plasma membrane of the cells promote the entry of glucose molecules from the extracellular matrix to the cytosol of the cell. Could someone explain how does the nutrient molecule enter the extracellular space from the blood vessel?
For instance, in the context of the pancreas, the walls of the blood vessel is fenestrated. The literature also provides evidence for the presence of connexon in the endothelium of the capillaries.
My doubt is, the nutrient molecule that diffuses from the blood vessel reaches the cytosol of the cell through
Diffusing through connexon ?(or)
Does it reach the interstitial matrix(the fluid surrounding the cells) and then uptaken by the transporters present in the plasma membrane of the cell? I think I understand your question, Natasha. In short, your own answer #2 is correct.
There are 3 spaces, and 2 pathways for glucose to pass from one to the next:
intracapillary plasma
extracellular fluid
the cytosol.
Ways glucose gets into the cell:
(2->3) To get from the ECF to the cytosol , glucose always needs a transport protein. These are the GLUTs. In two cases, the small intestine and kidney, these are part of a secondary active transport system based on the Na/K-ATPase. In the pancreas, it's GLUT2.
(1->2) To get from the capillary plasma to the ECF requires filtration, the process of applying hydrostatic pressure to the plasma and literally squeezing it like a sponge. The boundary of the "blood sponge" is the basement membrane. The membrane holds in the proteins, and lets anything dissolved in the watery serum (like glucose) through.
The Filtration Constant Kf is proportional to the percentage of the BM that is exposed in a given capillary, which varies by the type and other factors like histamine release.
The following is multiple choice question (with options) to answer.
Short chains of two amino acids (dipeptides) or three amino acids (tripeptides) are also transported actively. however, after they enter the absorptive epithelial cells, they are broken down into their amino acids before leaving the cell and entering the capillary blood via what? | [
"convection",
"osmosis",
"absorption",
"diffusion"
] | D | transports an amino acid varies. Most carriers are linked to the active transport of sodium. Short chains of two amino acids (dipeptides) or three amino acids (tripeptides) are also transported actively. However, after they enter the absorptive epithelial cells, they are broken down into their amino acids before leaving the cell and entering the capillary blood via diffusion. |
SciQ | SciQ-912 | evolution, mycology
Title: Why are some fungi poisonous? There are many poisonous fungi in nature. For example Amanita Phalloides.
What reasons could a fungus need poison for? Some species, like venomous snakes, use poison to kill other species as prey. But what about fungi? I can't think of any purpose for poison in fungi. If poison has no real function in fungi shouldn't evolution get rid of it? The same reason some plants are poisonous: to stop animals from eating them.
The visible part of the fungus is called, rather misleadingly, the fruiting body. It exists to produce and spread spores and thus produce the next fungal generation. Getting eaten, rather obviously, inhibits its ability to do this. Being poisonous discourages animals from eating the fruiting body and thus permits it to complete its life cycle.
The following is multiple choice question (with options) to answer.
What do fungi use to penetrate deep into decaying matter? | [
"hyphae",
"cytoplasm",
"flagella",
"cilia"
] | A | Most fungi get organic compounds from dead organisms. Fungi use their hyphae to penetrate deep into decaying organic matter. They produce enzymes at the tips of their hyphae. The enzymes digest the organic matter so the fungal cells can absorb it. Fungi are the main decomposers in forests. They are the only decomposers that can break down cellulose and wood. They have special enzymes for this purpose. |
SciQ | SciQ-913 | cell-biology, terminology
Title: What is the difference between cytosol and cytoplasm? I've generally seen cytosol defined as the solution inside cells minus the organelles, cytoskeleton, etc and cytoplasm as the cytosol plus the organelles, cytoskeleton, etc. This naturally leads to the impression that cytosol is the cytoplasm minus all the solids. The problem here is that there are all sorts of other large molecules in the cells which could be thought of as solid. Are they also part of the cytosol or are they suspended in it? (I.e. are they part of the cytosol or are they non-cytosol components of the cytoplasm?)
Basically, I'm asking if the precise definition of cytosol is just anything in the cell that's not behind an endomembrane (save the exoskeleton) or if the dividing line is something else.
Subquestion: things can get even more terminologically confused because the cytosol is sometimes called the matrix. What the heck is the preferred terminology with this stuff? IMO, the definitive answer to this question is given in a paper by J. S Clegg. He traced the origin of the term cytosol to a book chapter by H. A. Lardy, and confirmed by email that Lardy had indeed coined the term. Their definition of cytosol is as follows:
... that portion of the cell which is found in the supernatant fraction after centrifuging the homogenate at 105 000 x g for 1 hour.
The following is multiple choice question (with options) to answer.
All living cells in multicellular organisms contain an internal cytoplasmic compartment, and a nucleus within the cytoplasm. cytosol, the jelly-like substance within the cell, provides the fluid medium necessary for this? | [
"meiosis",
"apoptosis",
"biochemical reactions",
"cell division"
] | C | Now that you have learned that the cell membrane surrounds all cells, you can dive inside of a prototypical human cell to learn about its internal components and their functions. All living cells in multicellular organisms contain an internal cytoplasmic compartment, and a nucleus within the cytoplasm. Cytosol, the jelly-like substance within the cell, provides the fluid medium necessary for biochemical reactions. Eukaryotic cells, including all animal cells, also contain various cellular organelles. An organelle (“little organ”) is one of several different types of membrane-enclosed bodies in the cell, each performing a unique function. Just as the various bodily organs work together in harmony to perform all of a human’s functions, the many different cellular organelles work together to keep the cell healthy and performing all of its important functions. The organelles and cytosol, taken together, compose the cell’s cytoplasm. The nucleus is a cell’s central organelle, which contains the cell’s DNA (Figure 3.13). |
SciQ | SciQ-914 | thermodynamics, atoms, phase-transition
But let's look at how the states change. In a solid, you have a bunch of atoms that can be thought of as masses connected by springs. As heat is added to the system, the atoms begin to vibrate in the lattice of springs. As more heat is added, they vibrate enough to break the springs. This is when the solid begins to melt and turn to a liquid.
Now you have a liquid where the atoms are all moving around but they aren't free to move wherever they want. More heat is added to the system and the atoms begin to translate faster and faster. Eventually they translate fast enough to overcome the forces that are holding them together in a liquid. Now they fly free and are a gas.
So ultimately, heat is energy that makes atoms and molecules move in some way. They may translate, rotate, vibrate, or the electrons may begin moving around depending on how much heat is there and what configuration the molecule has.
The following is multiple choice question (with options) to answer.
Under appropriate conditions, the attractions between all molecules in what state will cause them to form liquids or solids? | [
"gas",
"liquid",
"plasma",
"soild"
] | A | Forces between Molecules Under appropriate conditions, the attractions between all gas molecules will cause them to form liquids or solids. This is due to intermolecular forces, not intramolecular forces. Intramolecular forces are those within the molecule that keep the molecule together, for example, the bonds between the atoms. Intermolecular forces are the attractions between molecules, which determine many of the physical properties of a substance. Figure 10.5 illustrates these different molecular forces. The strengths of these attractive forces vary widely, though usually the IMFs between small molecules are weak compared to the intramolecular forces that bond atoms together within a molecule. For example, to overcome the IMFs in one mole of liquid HCl and convert it into gaseous HCl requires only about 17 kilojoules. However, to break the covalent bonds between the hydrogen and chlorine atoms in one mole of HCl requires about 25 times more energy—430 kilojoules. |
SciQ | SciQ-915 | phase
"Which elements form the most phases?" is an impossible question to give and absolute answer as we are limited to certain pressures and temperatures with which to experiment. The way experimentation is done is likely to bias any verifiable answer toward more practical materials.
The following is multiple choice question (with options) to answer.
What else besides temperature has an effect on the phase of a substance? | [
"resistance",
"energy",
"weight",
"pressure"
] | D | Butter is a fat that is a solid at room temperature. What type of fatty acid does butter contain? How do you know?. |
SciQ | SciQ-916 | quantum-field-theory, charge, field-theory
Title: Is there a field for which neutral particle and antiparticle, can be considered as positive and negative charge? I apologize, but QFT is not my domain. What I ask is connected with the question Do the fields exist without electric charges? .
By analogy with the electron and proton, that carry the electric charges of the electrostatic field, could a neutron and anti-neutron represent the positive, respectively negative, charges of some field? I am sure that, if the answer is positive, the supposed field is not the gravitational one. In the gravitational field all the charges (masses) are positive. The neutron is not a fundamental particle. It carries no electric charge, yet it can interact with photons as its components - the quarks - carry electric charge and thus couple to photons. Macroscopically/classical, these interactions cancel out since its net charge is zero, but quantumly, there is a very big difference between objects with charged components and objects with no charged components (or without components at all).
Additionally, quantumly, one would say "to be charged under some field" means to transform non-trivially under some gauge group. The Standard Model has the electroweak $\mathrm{SU}(2)_R \times \mathrm{U}(1)_Y$ and the strong $\mathrm{SU}(3)$ as gauge groups. The neutron is color-neutral and electrically neutral. A left-handed neutron composed of three left-handed quarks has an overall weak isospin of $\frac{1}{2}$, though, and is thus also overall "charged" under the weak $\mathrm{SU}(2)_L$, a right-handed neutron has weak isospin $0$ (Note that the actual states of a neutron may well be a superposition of the two). Since anti-particles have opposite quantum numbers (transform in the conjugate representations), a anti-neutron has either $-\frac{1}{2}$ or $0$ as the weak isospin of its chiral states. Therefore, you might say the neutron is (or can be) "charged under the weak interaction".
The following is multiple choice question (with options) to answer.
What type of charge does a neutron have? | [
"half charge",
"neutral or no charge",
"negative charge",
"positive charge"
] | B | three building blocks of most matter. (The third is the neutron, which is neutral, carrying no charge. ) Other charge-carrying particles are observed in cosmic rays and nuclear decay, and are created in particle accelerators. All but the electron and proton survive only a short time and are quite rare by comparison. |
SciQ | SciQ-917 | evolution, ornithology, palaeontology, herpetology, dinosaurs
A few words about pterosaurs
Along with birds and bats, pterosaurs are the other clade of vertebrates capable of powered, flapping flight. Pterosaurs fall within Reptilia (and Diapsida and Archosauria) along with Dinosauria, which includes birds. There are a lot of other extinct lineages in the tree that are not shown, e.g., ornithodirans that are not dinosaurs and not pterosaurs. Pterosaurs and birds share anatomical features that all reptiles, diapsids, archosaurs, and ornithodirans have, which is how we know that they are more closely related to each other than to other groups, like crocodiles. But their flight structures evolved independently and are anatomically distinct fro one another. So pterosaurs are flying reptiles but not flying dinosaurs.
These images might help you understand the above explanation.
The following is multiple choice question (with options) to answer.
Animals that molt their exoskeletons belong to which clade? | [
"protists",
"trichina",
"ecdysozoa",
"spirogyra"
] | C | Figure 27.13 Animals that molt their exoskeletons, such as these (a) Madagascar hissing cockroaches, are in the clade Ecdysozoa. (b) Phoronids are in the clade Lophotrochozoa. The tentacles are part of a feeding structure called a lophophore. (credit a: modification of work by Whitney Cranshaw, Colorado State University, Bugwood. org; credit b: modification of work by NOAA). |
SciQ | SciQ-918 | inorganic-chemistry, acid-base, ph
Title: What alkali and alkaline earth metal oxides will turn moist red litmus blue and finally white?
How many of the following will turn moist red litmus blue and finally white?
$\ce{Li2O}$, $\ce{KO3}$, $\ce{RbO2}$, $\ce{Cs2O2}$, $\ce{BeO}$, $\ce{MgO}$, $\ce{BaO2}$, $\ce{SrO}$.
Since bleach convert moist red litmus blue and then white, but how we can identify which compound will act as bleach ? The standard oxides $\ce{Li2O, MgO}$ and $\ce{SrO}$ are water soluble and hydrolyse to form hydroxides and a basic solution. $\ce{BeO}$ is insoluble in water.
$\ce{RbO2}$ is a superoxide which in aqueous solution undergoes disproportionation to $\ce{O2}$ and $\ce{OH-}$ so will give a blue litmus test.
The peroxides $\ce{Cs2O2}$ and $\ce{BaO2}$ react with water to give hydrogen peroxide and the hydroxides, so again a basic solution(source). The hydrogen peroxide produced will bleach the litmus paper.
$\ce{KO3}$(Potassium Ozonide) is highly unstable, decomposes in water to $\ce{O2}$ and $\ce{KOH}$
The oxides which will NOT decolorize litmus are $\ce{Li2O, MgO, BeO}$ and $\ce{SrO}$. The peroxides ($\ce{Cs2O2}$ and $\ce{BaO2}$), the superoxide($\ce{RbO2}$) and the ozonide($\ce{KO3}$) will decolorize litmus.
The following is multiple choice question (with options) to answer.
Alkaline earth metals are what color? | [
"silvery grey",
"white",
"black",
"reddish orange"
] | A | The alkaline Earth metals include all the elements in group 2 (see Figure below ). These metals have just two valence electrons, so they are very reactive, although not quite as reactive as the alkali metals. In nature, they are always found combined with other elements. Alkaline Earth metals are silvery grey in color. They are harder and denser than the alkali metals. All are solids at room temperature. |
SciQ | SciQ-919 | newtonian-mechanics, newtonian-gravity, orbital-motion, velocity, centripetal-force
Title: What causes tangential velocity of a planet to change in an elliptical orbit? I am confused about this concept of central force motion. We have read that object undergoing a change in velocity must possess acceleration. However, in elliptical orbit motion gravitational force is directed towards the radial direction, then what causes tangential velocity to change? I have read somewhere that there a component of gravitational force in the tangential direction as well, but I don't understand how?
Can anyone please help me with this? Let go of a stone while high up in the sky.
It comes crashing vertically down. Gravity pulls along with its velocity, so it speeds up and up and up.
Repeat but this time push it a bit sideways also. It still comes crashing down but lands a bit further to the side. The sideways speed and the downwards speed caused by gravity combine into a slightly tilted velocity.
Repeat but push much more sideways to start with. It now lands far away.
Repeat again but now push so much that the object moves so much sideways that it misses Earth.
It will now fly past Earth. On the other side of Earth gravity pulls backwards in it, so it slows down and falls back again in the exact same way from the other side. Again it misses Earth. And this is repeated (ideally). This is an elliptic path.
If you gave an even larger sideways speed to start with, the stone will miss Earth with a much larger margin, widening the ellisis.
At some initial sideways speed the ellipsis is just as wide as it is heigh - it is now a circular path.
An even larger sideways speed widens the circle so we again have an elliptic path, this time wide rather than tall.
The following is multiple choice question (with options) to answer.
What type of movement is caused by erosion from direct gravity? | [
"frictional movement",
"electron movement",
"normal movement",
"mass movement"
] | D | Outline the forces that act on particles in the nucleus. |
SciQ | SciQ-920 | the time constants. The period T is the time for one cycle. The vibration (current) returns to equilibrium in the minimum time and there is just enough damping to prevent oscillation. 2% of the starting value. damped harmonic motion, where the damping force is proportional to the velocity, which is a realistic damping force for a body moving through a °uid. The reduction in amplitude represents a loss of energy by the system. 6cm at the moment the quake stops, and 8.
The following is multiple choice question (with options) to answer.
What term is used describe energy released during an earthquake? | [
"resonance",
"seismic load",
"magnitude",
"blast"
] | C | For decades scientists have had equipment that can measure earthquake magnitude. The earthquake magnitude is the energy released during the quake. |
SciQ | SciQ-921 | energy, rotational-dynamics, energy-conservation, harmonic-oscillator, rotational-kinematics
The pure rolling means that bottom-most point of sphere or its point of contact with ground remains at rest with repect to ground. Two motions are going on simultaneosuly: Translational and rotational, which is summed up in the above image and leads us to: $$v_{cm}=\omega_{cm}r$$
The following is multiple choice question (with options) to answer.
What are the rolling motions during an earthquake called? | [
"tidal waves",
"seismic thrusts",
"velocity waves",
"surface waves"
] | D | There are two major types of seismic waves. Body waves travel through the Earth’s interior. Surface waves travel along the ground surface. In an earthquake, body waves are responsible for the sharp jolts. Surface waves are responsible for the rolling motions that do most of the damage in an earthquake. |
SciQ | SciQ-922 | 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 is the process that breaks down rocks into smaller pieces? | [
"erosion",
"weathering",
"bleaching",
"bracing"
] | B | |
SciQ | SciQ-923 | humidity, water-vapour
Title: Water vapor content versus specific humidity I am wondering the difference between water vapor content and specific humidity to determine the moisture availability in the atmosphere. Which one is more acceptable variable to determine the moisture availability in the atmosphere?
I need to show the moisture availability in the atmosphere in my study. So should I explain it through water vapor content or through specific humidity? I will explain the rainfall deficiency over a region For a study relating to rainfall, I would be inclined to look at total column water vapour (TCWV), also known as integrated water vapour (IWV) or precipitable water. They're all (more or less) the same thing.
The company Remote Sensing Systems describes it as:
Total column water vapor is a measure of the total gaseous water contained in a vertical column of atmosphere. It is quite different from the more familiar relative humidity, which is the amount of water vapor in air relative to the amount of water vapor the air is capable of holding. Atmospheric water vapor is the absolute amount of water dissolved in air. When measured in linear units (millimeters, mm), it is the height (or depth) the water would occupy if the vapor were condensed into liquid and spread evenly across the column. Using the density of water, we can also report water vapor in kg/m2 = 1 mm or g/cm2 = 10 mm.
For rain to form, clouds need to form first. Clouds need cloud condensation nuclei, but crucially, for clouds to form, the water vapour partial pressure needs to reach the saturation vapour pressure. The latter is strongly dependent on temperature (Clausius-Clapeyron relation), so a profile of relative humidity is not the most directly useful quantity. The total column water vapour describes how much liquid water might form, which is why it is sometimes even described as precipitable water.
You can get this product either from reanalysis (like ERA-5) or retrieved from hyperspectral infrared sounders, such as IASI, AIRS, or CrIS. Depending on where and when in the world you're looking at, there may also exist products from geostationary instruments.
The following is multiple choice question (with options) to answer.
What is the measurement for the amount of water vapor in the air? | [
"ambient",
"haze",
"humidity",
"saturation"
] | C | A: Humidity is a measure of the amount of water vapor in the air. When humidity is high, sweat evaporates more slowly because there is already a lot of water vapor in the air. The slower evaporation rate reduces the potential for evaporative cooling. |
SciQ | SciQ-924 | geology, geophysics, climate-change, carbon-cycle
We can see here in white numbers the most significant pre-industrial sources and sinks (at ~1000 years time scales). We can see that humans produce 9 Gigatons of carbon per year (GtC/yr), due to that extra inflow, photosynthesis is taking 3 GtC/yr more than before, and the ocean is taking an extra 2 GtC/yr as well. However, that is not enough to counteract the 9 GtC/yr we produce, and that is increasing the amount of carbon in the atmosphere at 4 GtC/yr. This means the level in the atmospheric "bath tub" is still rising.
If we were to keep those 9 GtC/yr we produce stable (i.e. not increasing production in the future). The concentration of $\ce{CO2}$ in the atmosphere will rise to a level high enough that the sinks will match the sources, for example with plants taking 5 GtC/yr and the ocean 4 GtC/yr, that would nicely balance the production. But that new equilibrium atmospheric $\ce{CO2}$ concentration would be high enough to rise Earth's temperature several degrees and force a whole reorganization of the Earth's climates.
Finally, we have to say that some of these $\ce{CO2}$ intakes, like the oceanic one, don't come for free, and have their own nasty consequences, like ocean acidification.
The following is multiple choice question (with options) to answer.
Major exchange pools of carbon include organisms and what else? | [
"the atmosphere",
"location",
"the intensity",
"duration"
] | A | Major exchange pools of carbon include organisms and the atmosphere. Carbon cycles more quickly between these components of the carbon cycle. |
SciQ | SciQ-925 | photons, material-science, absorption, optical-materials, glass
There are further complications to all of this as well. Will the light undergo scattering processes that may allow the light to move through a material, while changing directions and potentially even turning back on itself without being absorbed? Once light has been absorbed, does it simply dissipate the excess energy through the material as heat, fluoresce it back as visible light (and in what direction?), or even do more "forbidden" transitions such as phosphorescence? The answer to all of these questions is "yes, but in varying degrees specific to the material." It even depends on the physical size and amount of material that you have present! So your worries about the rate at which light is able to pass through different materials really just becomes a question of how likely it is for the light to become "sidetracked" as it passes through the material. The net result is an apparent change in how fast the light passes through.
So finally, we can connect all of these nuanced ideas which could each fill a book of discussion on their own (and have) to the macroscopic perspective. All of these properties, for a material like a bulky glass window pane, can be summarized with three simple parameters such as the coefficients of absorption, transmittance, and reflectance of the material. Obviously, for light moving through normal glass, there is an overwhelming victory of the transmittance effects over the absorption and reflectance effects. Of course, you have also clearly experienced that standing at an alternate angle changes the propensity of reflectance of different kinds of light, mostly because you have changed the relative orientation of the light with respect to the overarching structure of the glass itself. This is explained much more deeply within the field of chemical crystallography.
The following is multiple choice question (with options) to answer.
When light is absorbed by a material, what may increase? | [
"happiness",
"mass",
"its temperature",
"weight"
] | C | Light may be absorbed by matter. This is called absorption of light. When light is absorbed, it doesn’t reflect from or pass through matter. Instead, its energy is transferred to particles of matter, which may increase the temperature of matter. |
SciQ | SciQ-926 | waves
Title: Is there a specific branch of physics that studies waves? Is there a branch of physics that studies waves and how they propagate through air, wires etc.? Acoustic physic deals with mechanical waves. But as CuriousOne says, many areas of physics uses waves in some way, so it's hard to pinpoint a "wave-only" physics.
The following is multiple choice question (with options) to answer.
What branch of physical science looks at how heat, work, and various forms of energy are related to one another? | [
"photosynthesis",
"frigidity",
"transformations",
"thermodynamics"
] | D | Just as the burning of wood releases energy in the form of heat, many other chemical reactions also release heat. There are also chemical reactions, such as photosynthesis in plants, which absorb energy in the form of heat. The study of energy changes in chemical reactions is called thermochemistry . The broader term thermodynamics also looks at how heat, work, and various forms of energy are related to one another. In this lesson, we will study the difference between reactions that absorb versus release heat as well as how to measure this change in energy. |
SciQ | SciQ-927 | 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.
Connective tissues typically have three characteristic components in common: cells, large amounts of amorphous ground substance, and what else? | [
"white blood cells",
"antioxidants",
"protein fibers",
"hormones"
] | C | 4.3 | Connective Tissue Supports and Protects By the end of this section, you will be able to: • Identify and distinguish between the types of connective tissue: proper, supportive, and fluid • Explain the functions of connective tissues As may be obvious from its name, one of the major functions of connective tissue is to connect tissues and organs. Unlike epithelial tissue, which is composed of cells closely packed with little or no extracellular space in between, connective tissue cells are dispersed in a matrix. The matrix usually includes a large amount of extracellular material produced by the connective tissue cells that are embedded within it. The matrix plays a major role in the functioning of this tissue. The major component of the matrix is a ground substance often crisscrossed by protein fibers. This ground substance is usually a fluid, but it can also be mineralized and solid, as in bones. Connective tissues come in a vast variety of forms, yet they typically have in common three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. The amount and structure of each component correlates with the function of the tissue, from the rigid ground substance in bones supporting the body to the inclusion of specialized cells; for example, a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris. |
SciQ | SciQ-928 | nitrogen
Step three is when plants and the animals that live of the plants die and breaks down into ammonia and other waste products (this is where many explanations of the nitrogen cycle usually starts). The waste products gets converted into ammonia by bacteria and the ammonia gets converted to nitrite and the entire cycle starts all over again.
Legumes have a symbiotic relationship with some bacteria that can fixate nitrogen (N2) https://aces.nmsu.edu/pubs/_a/A129/
sources:
https://science.howstuffworks.com/life/biology-fields/nitrogen-cycle.htm
https://www.britannica.com/science/denitrifying-bacteria
The rest is from my memory.
The following is multiple choice question (with options) to answer.
After what stage do the last 2 stages of food processing occur? | [
"digestion",
"filtration",
"circulation",
"excretion"
] | A | |
SciQ | SciQ-929 | botany, terminology, fruit
Title: What is the name of this part in plants, fruits, vegetables? What is the name of this part of the plant, fruit, vegetable? The thing that the plant is connected with the tree and gets nutrients with? The part we usually cut out when eat fruit.
Examples below
Papaya
Banana
Mango 'Stalk' or 'pedicel' would be an appropriate term (see, for example, this paper or this one). Specifically, you could say 'terminal part of the stalk/pedicel', though I don't know if there is a word for that.
Note that the term pedicel is commonly used for the stalk of a flower; it makes sense to use it for fruits too as they are derived from flowers.
The following is multiple choice question (with options) to answer.
What part of the plant holds the plant upright? | [
"leaves",
"notochord",
"roots",
"the stem"
] | D | Stems hold plants upright, bear leaves and other structures, and transport fluids between roots and leaves. Like roots, stems contain dermal, ground, and vascular tissues. Trees have woody stems covered with bark. |
SciQ | SciQ-930 | optimization, circuits, software-testing
Title: Finding minimal and complete test sets for circuits I have been playing around with analysis of circuits and am trying to generate test vectors. In order to exercise the circuit in the manner I require, I need a vector that includes every change in the circuit's inputs where only 1 input toggles, but in order to be efficient, it must include each change only once and must not include any changes where more than one input toggles. Inputs can be only logic high (1) or low (0). If these sequences don't already have a name I would like to call them Majella tuples.
I believe the length of these Majella tuples to be ((2^n) * n) + 1 where n is the width of the input in bits.
for example (with all 0 starting patterns):
n = 1:
0
1
0
n = 2:
00
10
11
01
11
10
00
01
00
n = 3:
000
100
110
010
110
111
011
001
101
001
011
111
101
111
110
100
101
100
000
010
011
010
000
001
000
I have written a bit of code to brute force generate these codes. However, it starts to struggle at n = 5 (actual code in a prev. revision of this question).
FUNCTION gen
IF height of stack == ((2^bit_width) * bit_width)
PRINT ZERO_PATTERN
RETURN TRUE
IF the change between the value at the top of stack and value does occur between other values on the stack
RETURN FALSE
PUSH value to stack
WHILE shift < bit_width
IF RECURSE with value as (value XOR (1 << shift)) returns TRUE
PRINT value
RETURN TRUE
shift = shift + 1
RETURN FALSE
SET stack to an empty list
SET bit_width to n
CALL gen with value as 0
The following is multiple choice question (with options) to answer.
What is a circuit that consists of one loop called? | [
"series circuit",
"dramatic circuit",
"episode circuit",
"speaking circuit"
] | A | A circuit that consists of one loop is called a series circuit. If its single loop is interrupted at any point, no current can flow through the circuit. |
SciQ | SciQ-931 | 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.
Leaves respond to these environmental stimuli by producing less what? | [
"carbonate",
"energy",
"chlorophyll",
"oxygen"
] | C | Vertebrates have a closed circulatory system with a heart. Blood is completely contained within blood vessels that carry the blood throughout the body. The heart is divided into chambers that work together to pump blood. There are between two and four chambers in the vertebrate heart. With more chambers, there is more oxygen in the blood and more vigorous pumping action. |
SciQ | SciQ-932 | evolution, zoology, taxonomy, phylogenetics
The apomorphy that defines the tetrapods is "paired limbs". You have Amphibia to the left and Amniota to the right, whose apomorphy is " egg with extraembrionic membranes". Inside them, you have Reptilia, whose apomorphies are "skull with upper and lower fenestra and beta-keratin in epidermis". Turtles came from an ancestor with these characteristics. So, turtles belong to the monophyletic group of "Reptiles".
Post scriptum: You wrote that "turtles (specifically sea turtles) live on both land and water, very much like amphibians". Just a curiosity: the reason why sea turtles leave the water (sea) from time to time shows exactly that they are not amphibians! Amphibians, being non-amniotes, have eggs that survive under water (actually, with few exceptions, they need to be under water). Turtles, on the other hand, are amniotes, and the amniotic egg cannot be laid under water. That's why the turtles have to leave the water to lay eggs: because, contrary to the amphibians, they cannot lay eggs under water.
The following is multiple choice question (with options) to answer.
Mammals that lay eggs are called what? | [
"viviparous",
"herbivores",
"monotremes",
"marsupial"
] | C | Mammals have separate sexes and reproduce sexually. They produce eggs or sperm and must mate in order for fertilization to occur. A few mammals are oviparous. They lay eggs, which later hatch. These mammals are called monotremes. Most mammals are viviparous and give birth to live young. These mammals are either placental mammals or marsupials. Placental mammals give birth to relatively large and well-developed fetuses. Marsupials give birth to smaller, less-developed embryos. In both placental and marsupial mammals, the young grow and develop inside the mother’s body in an organ called the uterus. At birth, they pass through a tube-like organ called the birth canal, or vagina. |
SciQ | SciQ-933 | geophysics, oceanography, topography
Title: What are the striations or ridges in the eastern Pacific Ocean? Messing around on Google Earth recently I noticed a number of striations in the Eastern Pacific. These appear in an East-West orientation and seem to start on the North and South American continental shelves, and extend for roughly half the Pacific Ocean. For example one of these striations start in Santa Rosa Island off California and ends at Hawaii. These striations also appear to be roughly equally spaced at 8 degree intervals. The North and South American striations are angled with respect to each other and seem to converge at roughly Tahiti.
What causes these? I'm a fascinated novice.
EDIT
Some images to make things clearer (North Pole is top left):
Note the regularly spaced East-West parallel striations starting from the Equator and stepping north. In fact the striation on the Equator covers the entire Pacific.
Here a closer shot also shows fainter striations fanning out from Los Angeles: They are fracture zones.
I've annotated your image with the names of these very long, tectonically important features. They even have names, such as the Mendocino Fracture Zone:
I also labelled some survey tracks (rather subtle, very straight, very regular in width), which are data artifacts — these are the things you noticed radiating from the vicinity of Los Angeles.
There are yet other types of linear feature on the sea floor:
Transform faults are strike-slip faults connecting segments of spreading centres in the oceanic crust.
The spreading centres themselves.
Roughly linear archipelagos like Hawaii.
The long, curved trenches at convergent plate margins.
Images from Google Maps. Note: I edited this answer substantially after the OP clarified the question... and I learned about the difference between transform faults and fracture zones.
The following is multiple choice question (with options) to answer.
In what ocean is the mid-atlantic ridge located? | [
"pacific ocean",
"arctic ocean",
"indian ocean",
"atlantic ocean"
] | D | There is a lot of volcanic activity at divergent plate boundaries in the oceans. As the plates pull away from each other, they create deep fissures. Molten lava erupts through these cracks. The East Pacific Rise is a divergent plate boundary in the Pacific Ocean ( Figure below ). The Mid-Atlantic Ridge is a divergent plate boundary in the Atlantic Ocean. |
SciQ | SciQ-934 | graph-theory, formal-modeling, language-design, model-theory
Title: Any Graph is a Model (! or ?) I know this could be considered a pointless question. However despite I am quite convinced that any possible model (i.e. UML, SysML, natural language, math, etc.) can be defined by means of a graph I do not know if there is a way to formally prove there exist an isomorphism between the set of Models and the set of Graphs.
I guess one should first define what a model is and I guess a possible answer is that a model can be considered as a sentence of the language defined by its meta-model. Thus models are languages. The question is therefore if there is an isomorphism between the set of languages and the set of graphs or, less formally, if it is provable that any possible language can be represented by means of a graph. I guess that the Chomsky works on languages could help but I can not find a reference on the Internet of such demonstration. If you look at things from a model-theoretic perspective, the basic ingredients you have are atoms, relations, and functions. Atoms could be modelled using nodes of the graph, and binary relations and single argument functions could be modelled using graphs. If you are willing to allow hyper-edges in your graph, then the remainder of the relations and functions can be modelled.
I don't think that there is anything deep to this observation.
The following is multiple choice question (with options) to answer.
Models may be physical, conceptual, or what else? | [
"mathematical",
"experimental",
"fundamental",
"theoretical"
] | A | Models may be physical, conceptual, or mathematical. |
SciQ | SciQ-935 | microbiology, bacteriology
Title: Can a bacterium infect another bacterium? I researched about it by searching on Google and reading some bacteriological articles, but I did not get any answer. I also asked some of my teachers, and they were also a bit confused. Some said that it is possible and others said not. So the question remains:
Can a bacterium infect another bacterium? If so, how? Bdellovibrio bacteriovorus (BV) “infects” other bacteria:
Similar to a virus, BV attacks bacteria such as Escherichia coli (E. coli) by attaching to and entering its prey, growing and replicating within the cell, and then suddenly bursting out, releasing its progeny into the surrounding environment. — How bacteria hunt other bacteria
The following is multiple choice question (with options) to answer.
What is an organism that spreads bacteria or other pathogens? | [
"arc",
"plane",
"vector",
"section"
] | C | Some bacteria are spread by vectors. A vector is an organism that spreads bacteria or other pathogens. Most vectors are animals, commonly insects. For example, deer ticks like the one in Figure below spread Lyme disease. Ticks carry Lyme disease bacteria from deer to people when they bite them. |
SciQ | SciQ-936 | ecology, biogeography
Edit in response to comments
Comment about biome scale
The reason behind the scale comment is that typically we observe succession for a given habitat. Part of this stems from the origin of the succession ideas, where Frederic Clements posited that climate was the major driving factor of successional trajectories (Clements 1916). This would actually fit well with the biome view of succession, however in order for this model to explain all the variation we see in the world (eg. why a tree grows in location X but not location Y 4 metres away), you devolve into splitting the world into infinitesimally small micro-climates. Henry Gleason proposed a more individualistic model, which suggested that climate was just one influence, and that each plant species responds to a myriad of different environmental cues (Gleason 1927). The sum of these responses results in the community at a given location. This seems to fit better with our current understanding of succession but is not without problems. In a Gleasonian model, any variation can be expected to result in a different community. Since it would be strange for the pampas region to be homogeneous over 1.2 million km2, there are likely distinct communities within the biome, each developing as a result of factors like soil moisture, soil chemistry, climate, wind exposure, and herbivore use. One can still talk about succession at a biome scale, but at that scale we would be thinking about what factors lead the pampas region to become a grassland, rather than what factors lead grass X, tree Y and forb Z to coexist next to each other.
Factors maintaining grassland type ecosystems are fairly uniform globally. You need some sort of event that will kill woody vegetation but not kill grasses and forbs. Fire and grazing are natural examples (Briggs et al. 2002), but mowing would also maintain grassland (Fidelis et al. 2012). Earthquakes are unlikely to maintain grassland as trees and shrubs are likely to survive earthquakes.
Comment about global pampas
The following is multiple choice question (with options) to answer.
What influences the types of plants and animals that inhabit a specific biome? | [
"cooling",
"Water",
"carbon",
"climate"
] | D | Climate influences the types of plants and animals that inhabit a specific biome. |
SciQ | SciQ-937 | human-biology, eggs
In order to form a zygote (fertilized egg) to develop properly into a fetus it has to be an environment to meet it needs. In a female uterus all these needs are met but replicating them might be difficult. An artificial womb would have to be able to provide nutrients, oxygen, and channels for the development process of a fetus as well as system to expel (birth) the fetus once its development is complete. So can today's technology and science do all this? In theory yes, if resources and time where dedicated (and red tape cut) it would be possible to develop a fertilized egg in an artificial environment within the foreseeable future. There have been multiple experiment where artificial wombs were implanted with fertilized eggs and began to grow but were stopped due to legality.
I encourage you to read the following Wikipedia and motherboard articles regarding artificial wombs and ectogenesis.
https://en.wikipedia.org/wiki/Artificial_uterus
http://motherboard.vice.com/read/artificial-wombs-are-coming-and-the-controversys-already-here
*Note there is a lot of biology I did not mention regarding zygote to fetus development which is the biggest question/obstacle that ectogenesis might face
The following is multiple choice question (with options) to answer.
In the vast majority of ectopic pregnancies, the embryo does not complete its journey to what organ, and instead implants in the uterine tube? | [
"uterus",
"ovaries",
"stomach",
"vagina"
] | A | Development of the Embryo In the vast majority of ectopic pregnancies, the embryo does not complete its journey to the uterus and implants in the uterine tube, referred to as a tubal pregnancy. However, there are also ovarian ectopic pregnancies (in which the egg never left the ovary) and abdominal ectopic pregnancies (in which an egg was “lost” to the abdominal cavity during the transfer from ovary to uterine tube, or in which an embryo from a tubal pregnancy re-implanted in the abdomen). Once in the abdominal cavity, an embryo can implant into any well-vascularized structure—the rectouterine cavity (Douglas’ pouch), the mesentery of the intestines, and the greater omentum are some common sites. Tubal pregnancies can be caused by scar tissue within the tube following a sexually transmitted bacterial infection. The scar tissue impedes the progress of the embryo into the uterus—in some cases “snagging” the embryo and, in other cases, blocking the tube completely. Approximately one half of tubal pregnancies resolve spontaneously. Implantation in a uterine tube causes bleeding, which appears to stimulate smooth muscle contractions and expulsion of the embryo. In the remaining cases, medical or surgical intervention is necessary. If an ectopic pregnancy is detected early, the embryo’s development can be arrested by the administration of the cytotoxic drug methotrexate, which inhibits the metabolism of folic acid. If diagnosis is late and the uterine tube is already ruptured, surgical repair is essential. Even if the embryo has successfully found its way to the uterus, it does not always implant in an optimal location (the fundus or the posterior wall of the uterus). Placenta previa can result if an embryo implants close to the internal os of the uterus (the internal opening of the cervix). As the fetus grows, the placenta can partially or completely cover the opening of the cervix (Figure 28.7). Although it occurs in only 0.5 percent of pregnancies, placenta previa is the leading cause of antepartum hemorrhage (profuse vaginal bleeding after week 24 of pregnancy but prior to childbirth). |
SciQ | SciQ-938 | 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.
In a single-celled organism such as chlamydomonas, there is no what after fertilization? | [
"meiosis",
"mitosis",
"spawning",
"germination"
] | B | Reproduction of Green Algae Green algae reproduce both asexually, by fragmentation or dispersal of spores, or sexually, by producing gametes that fuse during fertilization. In a single-celled organism such as Chlamydomonas, there is no mitosis after fertilization. In the multicellular Ulva, a sporophyte grows by mitosis after fertilization. Both Chlamydomonas and Ulva produce flagellated gametes. |
SciQ | SciQ-939 | applied-chemistry, viscosity
Some perflurocarbons are actually being investigated as human blood substitutes - they can transport and release oxygen to tissues. Perfluorodecalin is a prime example. As shown below, it is basically a naphthalene ring in which all of the hydrogens and double bonds have been replaced with fluorine.
The following is multiple choice question (with options) to answer.
Timber, medicines, dyes, oils, and rubber are just some of the useful products humans derive from what? | [
"plants",
"roots",
"fossils",
"flowers"
] | A | Plants provide many products for human use. They include timber, medicines, dyes, oils, and rubber. |
SciQ | SciQ-940 | evolution
Title: Is there any genetic similarity that defy evolution theory? For example,
say species A is common ancestor of B, and C. Species B is a common ancestor of D and E.
We would expect that there will be more genetic similarity between D and E than D and C. And those genetic similarity must exist in B.
In other word, we won't expect genetic similarity that don't "cross" the common ancestor or the evolutionary tree.
The exception is probably genetically engineered bacteria.
That being said, am I correct?
Some people say that we have similarity with pigs and chimps even though our common ancestors may be to far off. That won't happen right?
To summarize
I expect that evolutionary tree will form a well, tree. Genetic similarity would infect "nearby" trees and can't jump between trees without connectors, such as common ancestors.
Is that what we observe for ALL species? You have an excellent answer from Remi.b already but I just wanted to add/emphasise this (because there is always more than one way of explaining something and IMO the site benefits from having many answers to the questions)...
The tree we construct does not necessarily accurately reflect what happened in evolution. If B & C evolved from A, and D & E came from B, we would create this tree if we measured using the correct indicator. But the methods we have are not perfect. The first evolutionary trees were based on morphological descriptions etc. and clearly some of the classifications were going to be wrong. These days we use molecular methods, which are probably more accurate but could also be wrong some times. For example if we based our phylogeny on one SNP variant we could have some idea about the phylogeny between a few species, but if we based it on millions of SNPs we would have a much better idea - as technology & models improve that is becoming more realistic. The key point here being there is a difference between the trees we can draw from evidence, and the real evolutionary tree.
The following is multiple choice question (with options) to answer.
Differences between organisms reflect differences between their nucleotide sequences rather than between their what? | [
"environments",
"genetic codes",
"molecular codes",
"amino acids"
] | B | |
SciQ | SciQ-941 | zoology, ecology
Giraffes' this is an energy saving feature. Giraffes don't need to use muscles to hold their neck. They just use when flexing their necks down, when drinking water etc.
According to Wikipedia, for an alternative hypothesis Ouranosaurus have a hump. (Other hypothesis is display sail or termoregulation sail of course. Also spinosaurus have this kind of alternative hypotesis but this hypothesis not accepted much as sail. and spinosaurus' spine different from bisons. Bison spines concentrating at shoulder but spinosaurs' not at the shoulder. You can find spinosaurus info from this page.)
The following is multiple choice question (with options) to answer.
Lying with their mouths open, a behavior called gaping, probably serves what function for crocodiles? | [
"cooling down",
"sleeping",
"eating",
"digesting"
] | A | All crocodilians have, like humans, teeth set in bony sockets. But unlike mammals, they replace their teeth throughout life. Crocodiles and gharials (large crocodilians with longer jaws) have salivary glands on their tongue, which are used to remove salt from their bodies. This helps with life in a saltwater environment. Crocodilians are often seen lying with their mouths open, a behavior called gaping . One of its functions is probably to cool them down. |
SciQ | SciQ-942 | nitrogen
Step three is when plants and the animals that live of the plants die and breaks down into ammonia and other waste products (this is where many explanations of the nitrogen cycle usually starts). The waste products gets converted into ammonia by bacteria and the ammonia gets converted to nitrite and the entire cycle starts all over again.
Legumes have a symbiotic relationship with some bacteria that can fixate nitrogen (N2) https://aces.nmsu.edu/pubs/_a/A129/
sources:
https://science.howstuffworks.com/life/biology-fields/nitrogen-cycle.htm
https://www.britannica.com/science/denitrifying-bacteria
The rest is from my memory.
The following is multiple choice question (with options) to answer.
What type of living things break down dead organisms and recycle their nutrients into the soil? | [
"probiotics",
"producers",
"decomposers",
"consumers"
] | C | |
SciQ | SciQ-943 | digestive-system
Title: Energetics and Products of Pepsin/HCl Protein Digestion What are the energetics of protein digestion during which the enzyme pepsin is "activated" (whatever that means) by HCl? I've looked and been unable to find anything like a chemical equation that includes an energy term.
Of course, pepsin, being an enzyme, is not used up in that sought-for equation. Is HCl used up? If so, what are the products? How and in what form is the chlorine removed, assuming the HCl is consumed in the equation? This is well-explained on the Wikipedia page for pepsin. You are misinterpreting the use of the word activated. The protein is secreted by chief cells in the gastric glands in the form of pepsinogen, an inactive pro- form which has an extra ~40 amino acids at its N-terminus (the propeptide). The propeptide binds at the catalytic site of the enzyme and keeps it inactive. At low pH (this is where the HCl comes in - HCl secreted by parietal cells of the gastric glands acidifies the stomach) the protein is able to cleave off its own propeptide, making it fully active.
The following is multiple choice question (with options) to answer.
When food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin? | [
"calcium",
"white blood cells",
"ph",
"acid"
] | C | produced in cells located in the stomach wall. When food enters the stomach after a period of fasting, pepsinogen is converted to its active form—pepsin—in a series of steps initiated by the drop in pH. Pepsin catalyzes the hydrolysis of peptide linkages within protein molecules. It has a fairly broad specificity but acts preferentially on linkages involving the aromatic amino acids tryptophan, tyrosine, and phenylalanine, as well as methionine and leucine. Protein digestion is completed in the small intestine. Pancreatic juice, carried from the pancreas via the pancreatic duct, contains inactive enzymes such as trypsinogen and chymotrypsinogen. They are activated in the small intestine as follows (Figure 20.7 "Activation of Some Pancreatic Enzymes in the Small Intestine"): The intestinal mucosal cells secrete the proteolytic enzyme enteropeptidase, which converts trypsinogen to trypsin; trypsin then activates chymotrypsinogen to chymotrypsin (and also completes the activation of trypsinogen). Both of these active enzymes catalyze the hydrolysis of peptide bonds in protein chains. Chymotrypsin preferentially attacks peptide bonds involving the carboxyl groups of the aromatic amino acids (phenylalanine, tryptophan, and tyrosine). Trypsin attacks peptide bonds involving the carboxyl groups of the basic amino acids (lysine and arginine). Pancreatic juice also contains procarboxypeptidase, which is cleaved by trypsin to carboxypeptidase. The latter is an enzyme that catalyzes the hydrolysis of peptide linkages at the free carboxyl end of the peptide chain, resulting in the stepwise liberation of free amino acids from the carboxyl end of the polypeptide. Figure 20.7 Activation of Some Pancreatic Enzymes in the Small Intestine. |
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