source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-4901 | acoustics, resonance, vibrations
Safesphere's answer is excellent, and explains many things I wanted to know.
My remaining question is kind of academic and maybe not worth answering, but I'm still curious. I'll approach it as a thought experiment.
Imagine you have a guitar wire with the ends embedded in two concrete walls, stretched. No give in those walls at all. You clamp a small fishing weight onto the wire at the midpoint. If you pluck the wire, you are clearly causing lateral motion. The string will vibrate laterally because of the mass of the fishing weight versus the stretch of the wire. The string is a spring, and its vibration depends on mass versus stretch.
Now imagine you take that same guitar wire and instead connect one end to a dynamometer. If the vibration is slow enough, I expect you will see the load changing in a sine wave when you pluck the string. And I expect it will be mostly because of the change in the longitudinal force from the stretched string, and not because of the angular change from the string's transverse vibration.
Similarly, if you connect a sounding board to one end of the string instead of a solid concrete wall, I expect the effect on the sounding board is probably more from the change in tension than from the transverse motion of the string.
But this is a picky point, probably not worth a lot of argument. The string oscillations are mainly transverse (a standing wave). The string motion causes the tension to oscillate thus applying a varying force on the guitar top through the bridge and saddle. The string engage the air very little (as is evident on an electric guitar without amplification). This is because the acoustic wave impedance of the air does not match that of the string, so the energy transfer is not efficient. The guitar top acts as a transformer matching the impedances. The string tension moves the top and the top moves the air.
The following is multiple choice question (with options) to answer.
With extended feet, this creature may grab bass from overhead. | [
"bees",
"shark",
"sparrow",
"eagle"
] | D | eagles eat fish |
OpenBookQA | OpenBookQA-4902 | thermodynamics, everyday-life
Title: Why do fruits left to dry in the sun feel so much warmer to the touch than other objects outside? I have been putting preserved plums, on a rack, to sun and dry on my balcony. When I take them in at dusk, the plums are noticeably hot to the touch. They feel warmer than the bamboo and metal racks they are on, the cardboard box I put the racks on, the netting I put over the lot, and the air outside. (Note that ambient air temperature doesn't start dropping until well after I have the plums indoors.) The balcony itself, made out of a light-colored concrete-like composite, and the metal railing also feel warm, but not as much as the plums do.
I recall some relevant concepts from physics classes, but I can't tell if I'm taking into account everything at play. Here's what I have so far:
Plums are mostly water, which has a high specific heat (~4 kJ/kg/K) relative to air (~1 kJ/kg/K) and probably the other objects. I'm guessing the balcony also has a higher specific heat than air. Higher specific heat means that by the end of the day, the plums have stored more thermal energy than the cardboard box.
Water and metal are good thermal conductors, so they will feel warmer to my hands than the other objects even if they contain the same energy per unit.
Is there something else in here about the plums converting radiant energy to thermal that the other objects don't, or something about air flow? Is it a sign (which I suppose is not for Physics.SE) of fermentation? You were on track...and then missed the mark.
Higher specific heat means that by the end of the day, the plums have stored more thermal energy than the cardboard box."
Correct. You're on track...
Water and metal are good thermal conductors, so they will feel warmer to my hands than the other objects even if they contain the same energy per unit.
The following is multiple choice question (with options) to answer.
A plum tree's purple leaves uses light energy to | [
"produce philosophy",
"create nourishment",
"distribute government propaganda",
"create noxious fumes"
] | B | a leaf performs photosynthesis |
OpenBookQA | OpenBookQA-4903 | newtonian-mechanics, estimation
Would the rock have created a seismic event of its own (if so, how large)?
Would the rock have created a crater? The energy of the rock at the time of hitting the earth is mgh.
No rock we know of is going to be able to survive this collision with out breaking into pieces.
Non the less it will be a big impact and depending on the geology of the location it hits a variety of reactions scenarios can happen.
If the soil is aggregate of silt and sand and gravel, it would part into several shear rupture sections which look like slices of shell pattern surfaces starting from the bottom surface of the rock and turning up exiting the earth surface a few hundred yards outside of the impact zone and probably even eject some material out like a bomb crater. This scenario will have shakes that could be recorded miles away.
The calculation of how much of the momentum of rock will be shared with the shear material and accelerating them will be involved but not impossible.
If the geology of the impact area is of very low bearing like mostly silt and loose clays, the rock my lose most of its kinetic energy by just sinking into the dirt mostly with a giant humph with a cloud of dust rising.
If the geology is hard or rocky with the 'optimal' amount of mass and resilience it could create a substantial earthquake by resonating with the impact.
The following is multiple choice question (with options) to answer.
What would a sedimentary rock likely hold? | [
"a trilobyte",
"a cookie",
"a wheatgrass shake",
"a diner"
] | A | nearly all fossils are found in sedimentary rock |
OpenBookQA | OpenBookQA-4904 | ethology, sociality, animal-psychology
Title: Frogs stop croaking at same time I know frogs start croaking at the same time to attract a female.
Why do they all stop at the same time? Calling is a risky activity because it makes the frog conspicuous to predators. When calling in a group, the risk to any given individual is minimized to the point that the minimal risk is outweighed by the advantage of attracting a mate. However, a single frog calling on his own is assuming all of the predation risk. So, the frogs are playing a bit of game theory and when too few are calling simultaneously to make the risk worthwhile, they will all tend to stop.
The following is multiple choice question (with options) to answer.
Some frogs may do what for their young | [
"use magic",
"space travel",
"urinate on them",
"eat candle wax"
] | C | a frog eats insects |
OpenBookQA | OpenBookQA-4905 | infection, amphibians
Title: What is this toad suffering from? Myiasis or chytridiomycosis? I found this toad on Aug. 29th at this location: position on osm
I think it is a bufo bufo, approx. 10 cm long. The nostrils seemed to be completely filled with a grey matter and from the activity of the floor of the mouth it apparently tried to breathe againgst this obstruction. It probably had enough oxygen via its skin though.
I tried to remove the obstruction using a blade of grass but this seemed to produce some pain as the toad closed its eyes on contact, so I stopped. The skin looked fairly normal and the toad was able to walk away after a while.
I can think of two causes for this condition.
Batrachochytrium dendrobatidis infestation
Lucilia bufonivora larvae
I could not see properly, if there were any larvae or unhatched eggs inside the nostrils, but as the rest of the skin seemed unharmed I assume the latter.
Is my assumption valid or is there even a third possibility? It is a female Bufo Bufo and you are right, there are toad fly (Lucilia bufonivora) larvae/eggs inside her nostrills. These flies lay their eggs inside toads' nostrills (specifically on Bufo Bufos) and the larvae start eating them. Sadly this disease ends up by the death of toad. They slowly eat nostrills, then mouth, eyes, and all the head.
Here's a photo of a male bufo bufo, without a head. Someone found it walking around at this situation. https://i.stack.imgur.com/I6twl.jpg
The following is multiple choice question (with options) to answer.
A frog would most likely eat | [
"a cockroach",
"another frog",
"a maple leaf",
"a mouse"
] | A | a frog eats insects |
OpenBookQA | OpenBookQA-4906 | sea-level, tides, seasons, flooding
Title: How was Venice flooded? If I understand this correctly, Venice was not flooded due to sudden rainfall causing rivers to overflow, but due to the high tides. These high tides were caused by an alignment of sun, which was expanding the waters of the oceans disproportionately on one hemisphere and moon, which shifted the center of gravity of the moon-earth system in such a way that water rose on the same hemisphere.
In the news articles that I see, they also mention strong winds. This would make sense. High baseline + waves = a lot of water in the city. But in these photos everything seems to be calm. No waves, no wind, just an abnormally high level of water:
https://www.theatlantic.com/photo/2018/10/venice-under-water/574396/?fbclid=IwAR1DWLs_W39ndpdLWLZ1f6wlDDw8ZJmcBqyVM555O9DL5a_DhuY0mPQDi38
For me this doesn't make any sense. If the winds subsided and the flooding was caused purely by tidal effects, which are astronomical events, shouldn't it have been predictable months, if not years in advance?
If the winds subsided and the flooding was caused purely by tidal effects, which are astronomical events, shouldn't it have been predictable months, if not years in advance?
The following is multiple choice question (with options) to answer.
What would cause a flood? | [
"overpopulation of an area",
"Mount Everest losing soil",
"lake erie getting too much rain water",
"a river running dry"
] | C | when a body of water receives more water than it can hold , a flood occurs |
OpenBookQA | OpenBookQA-4907 | human-biology, zoology, pathology
Title: Do humans contract more physical sicknesses and diseases than animals do? I wondered: If I get into the library and look into the medical section it is evident that there are thousands and thousands of different human physical diseases. But if I look into the section of animal diseases it is by no means as large as the human section.
But humans are by no means the only beings with extraordinarily cell complexity. Many other animals have an equal amount of cell complexity. So shouldn't other animals have an comparative equal amount of diseases ?
Naturally as humans we are much more interested in human physiology which would explain the discrepancy. But is there any evidence that animals, especially mammals, have not an equal amount of (still unknown) different diseases ?
Remark:
While a bit similar, this is not this question:
Why do humans seem so much more prone to disease than animals?
I am asking about the quantity of diseases, not if humans are especially prone for diseases.
ADDENDUM:
The difference between the questions is like
"Is building A more prone to fall in natural catastrophes than other buildings because it seems like it ?"
and
"How many faults have building A in comparison to other buildings ?"
A correct answer to the first question is: "We made a statistical comparison and building A is more/less/equal prone to fall in a natural catastrophe. The impression is wrong/right."
A correct answer to the second question is: "Building A has in fact a mean approximately 13 000 faults while other buildings have only 5400 faults. But the reason can be that the other building are inspected with less care." Or "No, they both have very likely something like 9000 faults".
The following is multiple choice question (with options) to answer.
When an animal gets any kind of illness, his physical health will | [
"inevitably be worse",
"get better",
"fly away",
"nothing"
] | A | illness has a negative impact on an organism 's health |
OpenBookQA | OpenBookQA-4908 | immunology, virology
Title: Why do people dying of immune deficiency diseases appear sick? Please forgive the obviously silly appearance of this question, and/or of the tenor which may come across as flippant or dismissive of real world suffering. My intention is none of the above.
As a layperson, I have always understood that the expression of our various colds/flus etc, while frequently mis-understood as being caused by the virus, are actually just manifestations of our own immunity fighting same. In other words, all the snot, and fever and inflammation are not caused *by the virus, they are a reaction *to the virus, as we fight it off.
My question then is why do people with AIDS (or similar immunity destroying affliction) appear sick? If they have weak or non-existent immune systems, following the above logic, would one expect to see them passing away while looking entirely healthy? Many of the symptoms of disease are indeed related to inflammation, but inflammation depends heavily (though not solely) on the innate immune response. Patients with AIDS and some of the other immunodeficiencies lose their adaptive immune response, not their innate response. Therefore they are capable of mounting an inflammatory response that is not effective in clearing pathogens (because it doesn't have help from the adaptive immune system) but can still cause symptoms.
More importantly, many symptoms of disease are not caused by the inflammatory response, but are related to organ and tissue damage caused by the infection. A patient with pneumonia may have a reduced inflammatory response but will still have difficulty breathing and signs of reduced oxygen supply simply because the lung tissue has been damaged by the pathogen.
The following is multiple choice question (with options) to answer.
Illness has a negative impact on the health of what? | [
"rocks",
"bricks",
"llamas",
"plastics"
] | C | illness has a negative impact on an organism 's health |
OpenBookQA | OpenBookQA-4909 | cardiology, implantation
Title: About a mechanical aid to the heart I saw a news story a few years ago (I think) about a girl with a poor heart having a device implant that took over only some of the functioning of her heart ( I think they called it a piggy-back device , or something like that). The extraordinary thing is that it not only helped her live but all the heart functions started to improve. It was as if giving part of the heart a chance to 'rest' allowed the whole heart to improve. If this procedure works could it be applied to other organs? Could a Piggy-Back device be made for the liver taking over only some of its functions for instance? Could such a thing help the liver functions to 'regenerate'? The function of heart is just to pump blood and nothing else. Though, it is a vital organ, its functions are limited. The device that you are talking about is a battery powered mechanical pump that performs the same function as heart.
Liver, however has a more complex function. One of its function is to synthesize and secrete certain molecules. A small artificial device cannot do that (you would need a bioreactor !!!).
We still haven't developed and artificial cell. Perhaps a consortium of bacteria can do some of the liver's functions but to culture them in right proportions and implant them without the risk of infection or their elimination is almost impossible as of now. You can clearly see that there are too many steps to be optimized.
The following is multiple choice question (with options) to answer.
A thing that may assist a living being in prolonging life is | [
"making bad decisions",
"quitting when tired",
"calibrating to changes",
"living in danger"
] | C | adaptations are used for survival |
OpenBookQA | OpenBookQA-4910 | 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.
During a vigorous workout which will need to increase? | [
"Balance",
"Pulse",
"Perspiration",
"Strength"
] | B | as energy required for an activity increases , pulse will increase |
OpenBookQA | OpenBookQA-4911 | thermodynamics, electricity, electrons
Title: Why does Joule heating not occur when no current flows through a conductor? Joule heating happens every time when the conduction electrons transfer kinetic energy to the conductor's atoms through collisions, causing these conductor's atoms to increase their kinetic and vibrational energy which manifests as heat. Then, why wouldn't it happen when no current is flowing through the conductor? When there is no current, the electrons are still moving randomly at a speed of $\mathrm{~10^5\ m/s}$, but at a zero average velocity.
Then, why don't these electrons collide with the atomic ions making up the system and transfer energy to them causing them to heat up even when no net current is flowing? When no current is flowing, the system is in thermal equilibrium. The electrons do transfer kinetic energy to the atoms through collisions, but the atoms also transfer kinetic energy to the electrons, and these two processes happen at the same rate, so there's no net energy transfer and the system neither heats up nor cools down. This is just the same as any other case of thermal equilibrium: effectively, the electrons and the atoms are at the same temperature, and that's why there's no heat flow.
However, when you switch the voltage on there is an electric current accelerating the electrons, which increases their kinetic energy. Now they have, on average, more kinetic energy to give to the atoms than the atoms have to give to them. This means that there is a net transfer of energy from the electrons to the atoms. Moving an electron in an electric field changes its potential energy, and this is where the energy for the heating ultimately comes from.
The following is multiple choice question (with options) to answer.
A wire can be caused to heat up when what kind of current flows through it? | [
"wind",
"rocky",
"water",
"zapping power"
] | D | electrical current running through a wire causes that wire to heat up |
OpenBookQA | OpenBookQA-4912 | ros, carrot-planner, global-planner
Title: carrot planner is simple, but can't make a robot move a goal?
I want to ask anyone a question. I'm interested in global planner. I checked a code of a carrot_planner. carrot planner is very simple, but I think that it can't make a robot move a goal in case of being an obstacle between start position and goal position. Because the path(target_x,target_y,target_yaw) is made of following.
goal_x = goal.pose.position.x;
goal_y = goal.pose.position.y;
start_x = start.pose.position.x;
start_y = start.pose.position.y;
diff_x = goal_x - start_x;
diff_y = goal_y - start_y;
diff_yaw = angles::normalize_angle(goal_yaw-start_yaw);
target_x = goal_x;
target_y = goal_y;
target_yaw = goal_yaw;
target_x = start_x + scale * diff_x;
target_y = start_y + scale * diff_y;
target_yaw = angles::normalize_angle(start_yaw + scale * diff_yaw);
Carrot planner seems to make a plan for a robot to go straight. I mean that robot stops in front of an obstacle.
What do you think of it?
Originally posted by Ken_in_JAPAN on ROS Answers with karma: 894 on 2014-06-09
Post score: 0
Yes; the carrot planner is intentionally stupid like this. I think the carrot_planner wiki describes it pretty well.
If you want obstacle avoidance you should use a more complex planner such as navfn or the sbpl_lattice_planner
Originally posted by ahendrix with karma: 47576 on 2014-06-09
This answer was ACCEPTED on the original site
Post score: 0
The following is multiple choice question (with options) to answer.
It is very difficult for carrots to grow in | [
"topsoil",
"Kansas",
"peat",
"adobe"
] | D | the looseness of soil has a positive impact on a plant 's roots' growth in that soil |
OpenBookQA | OpenBookQA-4913 | botany
Title: Do any plants exhibit hormonal changes similar to puberty? Just what the title states.
Are there any plants/trees that exhibit a growth spurt at a definite interval after the shoot appears? In flowering plants (the angiosperms) there are several developmental transitions in the life of the plant. I won't list the plants, because the list includes pretty much all of them (although the magnitude in the change of developmental pace differs widely between taxa and environments).
First there is seed germination, which is controlled hormonally. Absence of germination is usually imposed by abscisic acid, whilst germination is caused at the appropriate time by gibberellic acid and ethylene (among other things; Holdsworth, Bentsink & Soppe, 2008).
Next, in many herbaceous species there is a transition between a spreading growth stage (e.g. rosette growth) and the flowering stage. The 'growth spurt' here is the differentiation and elongation of the flowering stem, and then subsequently the sudden flowering of buds. The transition is also controlled hormonally, by a variety of hormones including auxin (Zhao, 2010), gibberellic acid, ethylene (Schaller, 2012), and the long anticipated, recently confirmed florigen (Choi, 2012). Ethylene and abscisic acid then play important roles in the next developmental transition when seeds and fruits are produced and dehisced.
Small RNAs are also now being revealed to play a large role in controlling the timing of developmental, but they are upstream of the hormonal changes. In particular some key miRNAs are involved in auxin-based regulation of branching, and in embryogenesis (Nodine & Bartel, 2010), and RNA silencing is involved in the switch from rosette growth to flowering growth (reviewed in Poethig, 2009 and Baurle & Dean 2006).
The following is multiple choice question (with options) to answer.
It is easiest for a rose to grow | [
"in concrete jungles",
"on tilled ground",
"in someone's stomach",
"on a brick"
] | B | the looseness of soil has a positive impact on a plant 's roots' growth in that soil |
OpenBookQA | OpenBookQA-4914 | human-biology, lifespan
Title: Is the human lifespan still expanding? Description
200 years ago, the human lifespan was roughly 35 to 40 years long. And it has doubled in length since then.
Question
Will the human lifespan continue to expand in length? If you mean to ask whether or not humans will be able to continue increasing their life expectancy without an upper bound, the answer is no. If you're asking if people live longer now than in the past and whether we can expect to see further increases, I'd guess that the answer is yes for most of the developed world, with the exception of the United States. The same is probably true for most of the developing world; it would definitely be true in the developing world if western corporations started paying them fairly for their labor or resources, but that's getting into an answer for a different stack exchange website.
I suppose I should qualify the "no" to unbounded life expectancy, because it could come down to definitions of alive. I don't think that it is outside the realm of possibility for science to provide techniques to artificially extend life; if we can start growing organs in labs, we might be able to just go change out our heart or kidneys much like we take our cars to have the tires changed. If you could figure out a way to take care of the circulatory / nervous system, too, who knows? As it stands, though, our cells have an upper limit on the number of times that they can reproduce because we don't have enough telomerase in somatic cells to prevent the eventual shortening of telomeres (special sequence of base pairs located at the ends of DNA molecules) to the point where they no longer protect the DNA during replication and the cell eventually dies as a consequence. Hell, if we could just figure out how to take care of that we could probably chalk on some extra time - then we can see which system would be next to fail and take us out.
The following is multiple choice question (with options) to answer.
Which sustains life yet stopped growing? | [
"air",
"a bush",
"a rock",
"a felled tree"
] | D | if a tree falls then that tree is dead |
OpenBookQA | OpenBookQA-4915 | classical-mechanics, conservation-laws
Title: Cat falling from a tree When a cat or any body falls over to the ground, how is momentum conserved?
I was working on a problem of a cat falling on top of a skateboard, and the system travels together with a new velocity. That seemed intuitive enough for me. This is how I was thinking through:
The cat had momentum that became zero after the impact. Should not the skateboard have recoiled in some way, due to the conservation of momentum? After all, the change in momentum for the board should have been something measurable.
I guess there is something wrong with the way I am approaching the problem. Could you please help me identify this?
EDIT: I apologise: but the situation is like this - a skateboard moves on the ground with constant speed, until the cat is dropped from a tree. The cat lands on the skateboard and then proceeds with a new speed. The skateboard does not have to move, especially if the force is perpendicular. The ground (or earth) can absorb the momentum. In other words the earth gains a slight amount of velocity!
The following is multiple choice question (with options) to answer.
If a tree falls then it is what? | [
"alive",
"expired",
"lush",
"growing"
] | B | if a tree falls then that tree is dead |
OpenBookQA | OpenBookQA-4916 | waves, pressure, acoustics, air
Title: How can sound waves propagate through air? We know that the sound waves propagate through air, and it can't travel through vacuum. so the thing that help it doing that is the air's molecules pressure. So my question how can that happens? I can't understand that concept. Sound waves propagate very similarly to how 'the wave' propagates at baseball stadiums:
http://www.youtube.com/watch?v=H0K2dvB-7WY
At some point something (your vocal cords, a piano string, a speaker) hit a bunch of air particles (atoms, molecules, it really doesn't matter). These particles in turn hit the particles next to them, these hit the ones next to them and so on. No pressure here is simply the absence of any particles, so nothing communicates the orders to move. This is like ' the wave' in that everyone communicates the motion of the wave of the person standing next to them, and if there is no one standing next to you, the wave ends with you. Hearing a sound is the last bunch of air particles next to your ear drum getting the instructions to vibrate which in turn vibrates your ear drum and your brain turns this response into the perception of sound.
The following is multiple choice question (with options) to answer.
Which is an example of sound reaching the ear? | [
"a cello",
"taste testing",
"a silent movie",
"a comic book"
] | A | when sound reaches the ear , that sound can be heard |
OpenBookQA | OpenBookQA-4917 | acoustics, air, displacement
\end{align}$$
That is a Very Loud Pop - about 80 dB. Even if we argue that only a small fraction of this pressure ends up in the audible range there is no doubt in my mind you would hear "something".
So yes, you can hear that parchment disappearing. No problem. Even if some of my approximations are off by a factor 10 or greater. We have about 5 orders of magnitude spare.
AFTERTHOUGHT
If you have ever played with a "naked" loudspeaker (I mean outside of the enclosure, so something like this one from greatplainsaudio.com):
The following is multiple choice question (with options) to answer.
sound can be heard when it reaches what? | [
"hearing organ",
"brain",
"eyes",
"neck"
] | A | when sound reaches the ear , that sound can be heard |
OpenBookQA | OpenBookQA-4918 | death, kidney
Title: For how long can a person drink sea water? How long could a person of lets say 18 years be able to drink sea water without getting too much into trouble ? Or can a person drink it without noticing that it is a very bad idea ? I don't mean in just 1 drink session but like can one manage a day or two ? Can one drink it and go to sleep and be still healthy (although very thirsty) in the morning ?
(this is just a hypothetical question, I'm not a scientist at all, I'm not sure what tags to use actually)
Additional brainstorming:
kidney failure
any other organ failure
dying of thirst
...
(source: free.fr)
Alain Bombard
He is a french biologist who voluntarily tested how many days a man can survive drinking seawater and how?
Biologist point of view
Sea contains ~3.5% of salt$^1$. Our kidney separates the waste from water and excrete them in urine provided the salt content is less than ~2%.$^2$
So, it will take the water already present in the body. Causing excessive thirst and dehydration, eventually cause death.
Alain's Experiment
Just one spoon of seawater at 20 minute intervals, drinking very
slowly and letting the saliva in your mouth reduce the saline in the
water you have swallowed.
Though he survived 65 days (From and including: Sunday, 19 October 1952
to Tuesday, 23 December 1952, ~4,400km) of his journey and lost 25 kg of weight, this result is never successfully reproduced.
Source:
http://oceanservice.noaa.gov/facts/whysalty.html
http://paradise.docastaway.com/drinking-sea-water
The following is multiple choice question (with options) to answer.
If someone is dying of thirst, they can hydrate by | [
"catching rain",
"visiting a valley",
"drink acid",
"find snow"
] | A | acid can cause chemical change |
OpenBookQA | OpenBookQA-4919 | evolution, botany, development, fruit, seeds
What is the point of fruit if not to be eaten? It’s my understanding that organisms will adapt to survive and thrive. I understand that being eaten can spread seeds, but this just seems like too much of a risky tactic to rely on.
Following on from part one: If being eaten is the best way to spread seed, why do some plants avoid this (such as by being poisonous or thorny)? Seeds are spread by many mechanisms
Wind dispersal: When air currents used to spread seeds. Often these plants have evolved features to facilitate wind catching, for example dandelions. Aka, anemochory.
Propulsion & bursting: When seeds are propelled from the plant in an such as in these videos. This is called Ballochory.
Water: Similarly to wind dispersal plants can spread seeds by water movement/currents, aka Hydrochory. This is used by many algae and water living plants.
Sticky Seeds: There are many ways a seed can attach to the outside of an animal - by using hooks, barbs, sticky excretions, hairs. Seeds then get carried by an animal and fall off later. This is epizoochory.
Fruiting: Plants can use seed-bearing fruit to encourage animals to eat the seeds. They will then be spread when the waste is excreted after digestion. This is a process of endozoochory.
More than one way to spread a seed
The following is multiple choice question (with options) to answer.
An example of seed dispersal is animals eating what? | [
"dirt",
"hard shells",
"grass",
"animals"
] | B | An example of seed dispersal is animals eating seeds |
OpenBookQA | OpenBookQA-4920 | organic-chemistry, physical-chemistry, biochemistry, alcohols
Title: Storage of Urine Not all may be favorable to this project, but I will explain what I am trying to do. I work at home, and instead of walking a moderate distance to the bathroom and loosing my focus, I've been, at times, peeing in a 3 Quart Poland Springs water bottle. If you take offense at this, please do not continue reading except to be helpful in the scientific goal. I know this subject won't suit many types of people, so just ignore it if that is your case.
I noticed first of all that urine is not at all as sterile as people say that it is. The rate of growth of bacteria is relatively slow, but as a precaution, I found the need to use additional measures to prevent the growth of bacteria. I settled on the following method: I have two bottles and I add to each bottle about enough salt as can be soluble in the urine and sometimes maybe a little more. The one bottle then fills up throughout the day and is emptied, washed, and refilled with salt. The salt helps to kill the bacteria which would be lingering in the empty bottle. The next day, the bottle stays empty and the other is used.
I would add that I discovered that the bacteria (without the salt) does not usually grow unless the bottle is left with urine for two days. After this, however, that same bottle (without the salt) would retain the bacteria and immediately grow, if used again.
This system works relatively well, so long as it is done every day. It will even withstand 2 days with only moderate growth. (If I should leave it by mistake for longer it can get ugly). Nevertheless, I am still looking to improve upon this. One reason is that, if I drink less water or relieve myself normally, the bottle does not fill in one day. I am looking for someone with knowledge of chemistry to help me find a substance that can be added to this solution which fits a number of common sense criteria. I will also add a list of the substances that I have tried or already considered.
Necessary qualities
The following is multiple choice question (with options) to answer.
Cactus store their liquids in their | [
"flowers",
"lockers",
"super market",
"trunks"
] | D | a stem is used to store water by some plants |
OpenBookQA | OpenBookQA-4921 | organic-chemistry, molecular-structure, molecules
Title: Complex organic molecules I am studying astronomy and came across the following term in the astrochemistry course called 'complex organic molecules' or also written as COMs. My question is: What is exactly meant with these molecules? Is it just a molecule with more than one carbon atom? tl;dr: two different definitions. Astronomy: multiple carbon atoms in molecule. Chemistry: polymer
Interestingly enough, after reading about COMs here, as well as reading the Wikipedia page and the corresponding arXiv paper, it seems like chemists and astronomers have different definitions of what a complex organic molecule should be!
As far as I knew, in chemistry complex organic molecules were long polymers, such as proteins, which were composed of thousands upon thousands of amino acid units. In the astronomy paper, however, they cite other types of molecules.
$\ce{CH3OH,
CH3CHO, HCOOCH3 and CH3OCH3}$, all cited as "complex" (haha) organic molecules in the paper, would appear to chemists as relatively simple molecules. (I read the paper, because it piqued my interest that something like a protein could be found in space). I then read the Springer article.
The term “complex organic molecules” is used differently in astronomy and chemistry. In astronomy, complex organic molecules are molecules with multiple carbon atoms such as benzene and acetic acid. These molecules have been detected in interstellar space with radio telescopes. In chemistry, “complex organic molecules” refer to polymer-like molecules such as proteins.
The following is multiple choice question (with options) to answer.
Which has molecules? | [
"a Popsicle",
"suicide",
"therapy",
"thoughts"
] | A | matter is made of molecules |
OpenBookQA | OpenBookQA-4922 | electrical-engineering, ethics, sales, safety
But all of those steps are going way above and beyond what you're obligated to do in this particular case. This is especially so when there is a safe usage for the product along with an unsafe approach. And any of those actions are likely to irreparably damage your relationship with that client. Damaging the relationship will impair your credibility with them and make it less likely that they'll listen to your concerns.
So your obligation is to lay it out to them in unambiguous terms that you believe they need to stop using the product in their "preferred" manner and that your firm will no longer provide any support whatsoever regarding future use of that product in that configuration.
The following is multiple choice question (with options) to answer.
Items are all ultimately compromised of which? | [
"Cells",
"Molecules",
"Air",
"Nerves"
] | B | matter is made of molecules |
OpenBookQA | OpenBookQA-4923 | newtonian-mechanics, forces, buoyancy, fluid-statics, weight
Keep in mind that a body loses weight in a liquid which is equal to the weight of the liquid displaced by it/equal to the buoyant force.
As for the bonus question, look into the answer to this question -
https://physics.stackexchange.com/a/296537/134658
The following is multiple choice question (with options) to answer.
If a liquid disappears then that liquid probably did what? | [
"gasify",
"condense",
"melted",
"solidified"
] | A | if a liquid disappears then that liquid probably evaporated |
OpenBookQA | OpenBookQA-4924 | everyday-life
Title: Strange pattern on car windows
A couple of days ago I was in a friend's car, and I noticed this pattern on the windows; I took a picture of the sun through the window to make it clearly visible.
The night before had been quite cold, but I don't think that the temperature went below $0$ °C, even though I am sure that it did some days before.
I can speculate that the phenomenon originated from some condensation/freezing of humidity on the outside of the car window, so I searched the web for pictures of water condensation and frost patterns (and also water staining) on car windows, but couldn't find anything similar.
What could be the origin of this intricate pattern? From your question, I can guess that the weather is rainy in your region.
When you drive a car in the rain, the water drops pass your windows at an angle. This, plus wind and other winter stuff causes the path of the drops to twist and jiggle like in this photo
I would also guess that the rain stopped while still driving, so the water could've evaporated in this pattern. The sunlight then makes those residues more pronounced when you took the picture.
Take a look at the following picture from a google search of 'water stains on glass'. To me it looks similar to your photo, just without the effect of moving window (keep in mind that the residues in the water may differ from one place to another due to pollution and etc., so the stains don't have to look the same).
The following is multiple choice question (with options) to answer.
What best explains a muddy road becoming dry later? | [
"alien heat rays",
"evaporation",
"precipitation",
"torrential rain"
] | B | if a liquid disappears then that liquid probably evaporated |
OpenBookQA | OpenBookQA-4925 | anatomy, scales
If this horse is 500 kg (a mid-range mass for horses), each leg would have to support 125 kg, compared to only 37.5 kg for a 75 kg adult. Why don't we see a corresponding difference in cross-section? Elephant, rhinoceros, &c all have much thicker legs in proportion. The answer, I think, lies in the fact that the animals you mention all evolved as cursorial animals (that is, they run to escape predators). Less mass in the lower leg means it swings easier, so the animal can run faster.
There are two things you're apparently not noticing in that picture. First, the the horse's lower leg is almost entirely bone (and some tendon), and it's bone that does the supporting. The propulsive power comes from the large muscles of the hip, thighs, and shoulders.
Second, the lower part of the leg (with the white wrappings) is not anatomically equivalent to the human's lower leg, but to the bones of the hand and foot. You can see this if you look closely at the rear leg in that picture. The femur, equivalent to the human's thigh, ends at the knee just above the belly line. Then the tibia extends about halfway down, ending at another joint which you might think is the knee, but which is called the 'hock' in horse-speak. The white-wrapped part is a metatarsal, equivalent to human foot bones, then there pastern bones equivalent to human toe bones, ending in the hoof/toenail.
So consider that you can, if reasonably fit, walk around on tiptoe without crushing your foot and toe bones, then imagine the end result of your ancestors having done this for the last several tens of millions of years :-)
PS: With horses, there is some effect from human selection, too. Racing & show breeds tend to have thin lower legs, draft horses & working breeds have proportionately thicker ones. My first horse, a thorobred/arab mix, had legs about as thick as my wrists (granted, I'm a fairly muscular guy); my current mustang, about the same height & weight, has legs about twice as thick.
The following is multiple choice question (with options) to answer.
Pit bulls thin their thicker coats by | [
"getting a haircut",
"shaving",
"shedding",
"selling"
] | C | shedding is when an animal loses hair |
OpenBookQA | OpenBookQA-4926 | atmosphere, moon, sun
Title: Why were both the sun and the moon red today? Today was a normal day, except the sun and moon colors were strange. After 5pm, the sky was covered with cirrostratus-like translucent clouds and the sky was a blend of blue and grey.
Everything would be fine, except that the sun was orange between 4-5pm. Then by around 5-6pm, the sun was completely red like blood even though it was still high up, and it was 1+ more hour to sunset.
Then, I didn't look at the sky until 8pm when it was already dark. When I went out, the moon was red just like the sun couple hours before.
The whole thing I saw from around south side od Chicago on US Labor Day (4 Sep, 2017). I didn't take pictures of the sun unfortunately because I disregarded its color, but I took pictures of the moon.
Here's how the moon looked through my phone camera, through binoculars:
Here is a similar picture but edited so that the moon looks exactly like I saw it with naked eye:
What can thia be caused by? (As of writing this at 10:06pm the moon is still red, and it is 6 hours since both the sun and the moon were red/orange)
EDIT: I also didn't see anything about this phenomenon in the media which is strange, and once again, this was seen from Chicago. Smoke. There was significant smoke across the USA, which attenuated the light from the sun/moon due to increased scattering. The smoke particles effectively cause the light to reflect in different directions, so you see more colors.
See below for the HMS Smoke Polygons for the day, which clearly shows smoke over your region from the intense smoke/wildfire activity in the Pacific Northwest. You can also see the NASA Worldview composite of VIIRS visible imagery for the day, with fire locations in red.
The following is multiple choice question (with options) to answer.
Over your head is dark though it is only afternoon on a summer's day. Lacking an eclipse of the sun, a viable reason for this darkness is | [
"the sky lacks clouds",
"the sun is shining",
"its about to storm",
"clouds are completely absent"
] | C | cloudy means the presence of clouds in the sky |
OpenBookQA | OpenBookQA-4927 | thermodynamics, electricity
Title: Removal of heat from a closed system using electricity I was thinking this morning about how heat could be removed from a system in such a way that it is stored for future use. My ideas are a form of thermo-electric system that converts heat into electricity which can be stored in batteries and capacitors. My question is, is it possible to use electricity as a medium to remove heat from a system? Using or generating the electricity is irrelevant, as long as more heat isn't generated. My goal is to remove heat without generating more heat. The closest existing solution to what you're looking for is probably Peltier cooling.
Of course Peltier coolers don't break the Second Law of Thermodynamics either: they are heat pumps, with a cold sink and a hot sink.
The following is multiple choice question (with options) to answer.
What might you use for heat? | [
"an ice cube",
"a mini flashlight",
"snow",
"glaciers"
] | B | a hand dryer produces heat |
OpenBookQA | OpenBookQA-4928 | electrostatics, electricity, water, everyday-life, air
Title: The Ultimate Hand Dryer I have come across many hand dryers that attempt to dry your hands really fast after you wash them. Here are two of them:
XLERATOR
http://www.exceldryer.com/
Dyson Airblade
http://www.dysonairblade.com/homepage.asp
So I guess I have a ridiculously high standard cause I think even these are too slow.
Would it be possible to create a large static electric field to attract the water molecules off of your hand? Can someone offer some ideas that would remove the water off of your hand using some type of electric field generated by charged plates or something? Water molecules don’t carry an electric charge (and if they do, you don’t want them on your hands…). The dipole moment of water molecules can only be used to rotate them in space, not to move them. Additionally, the forces that apply to water molecules on your hands also apply to water molecules in your hands. So even if you somehow managed to apply a sensible force on these water molecules, this would get rather uncomfortable. The same problem arises if you attempt to heat them up by means of electric resonance (similar to a microwave).
I therefore doubt that it would be possible to build a device based on electric fields rather than moving air, that removes water molecules from the surface of your skin.
However, it might be possible to vaporise the water on your hands using strong infrared lamps. This might lead to other problems, though, such as the focusing of infrared radiation on small areas of the skin by water drops.
The following is multiple choice question (with options) to answer.
People use hand dryers after washing their hands in order to | [
"fly",
"Remove the fire",
"clear away moisture",
"go to space."
] | C | a hand dryer produces heat |
OpenBookQA | OpenBookQA-4929 | microbiology, bacteriology
So, perhaps the answer is, a bacterium is dead when it is unable to reproduce, cannot be resuscitated, gene expression has ceased, and shows characteristic markers of apoptosis
[1] Transcriptional activity around bacterial cell death reveals molecular biomarkers for cell viability, Remco Kort, Bart J Keijser, Martien PM Caspers, Frank H Schuren and Roy Montijn, BMC Genomics 2008
[2] Can dead bacterial cells be defined and are genes expressed after cell death? Trevors JT1, J Microbiol Methods. 2012 Jul
[3] A matter of bacterial life and death Gregg Bogosian, Edward V Bourneuf
[4]Advances in microbial food safety: 23.
[5] Antibiotic-Induced Bacterial Cell Death Exhibits Physiological and Biochemical Hallmarks of Apoptosis, Daniel J. Dwyer, Diogo M. Camacho1, Michael A. Kohanski, Jarred M. Callura1, James J. Collins, Molecular Cell, Volume 46, Issue 5, 8 June 2012, Pages 561–572
The following is multiple choice question (with options) to answer.
when organisms die, they | [
"reproduce",
"wither away",
"petrify",
"regenerate"
] | B | dead organisms decay |
OpenBookQA | OpenBookQA-4930 | nuclear-physics, stability, binding-energy
Title: If we assume that protons don't decay, then will all matter ultimately decay into Iron-56 or into nickel-62? Wikipedia says that all matter should decay into iron-56. But it also says Nickel-62 is the most stable nucleus.
So could this mean that in the far future, everything could (through quantum tunneling) fuse and/or decay into nickel-62 rather than iron-56?
Question inspired by an interesting comment made on a post here: http://www.quora.com/Do-atoms-ever-deteriorate-over-time/answer/Alex-K-Chen/comment/574730 The binding energy curve, again in wikipedia, shows iron as the one with the smallest binding energy per nucleon. Though in the table, the following is stated:
56Fe has the lowest nucleon-specific mass of the four nuclides listed in this table, but this does not imply it is the strongest bound atom per hadron, unless the choice of beginning hadrons is completely free. Iron releases the largest energy if any 56 nucleons are allowed to build a nuclide—changing one to another if necessary, The highest binding energy per hadron, with the hadrons starting as the same number of protons Z and total nucleons A as in the bound nucleus, is 62Ni. Thus, the true absolute value of the total binding energy of a nucleus depends on what we are allowed to construct the nucleus out of. If all nuclei of mass number A were to be allowed to be constructed of A neutrons, then Fe-56 would release the most energy per nucleon, since it has a larger fraction of protons than Ni-62. However, if nucleons are required to be constructed of only the same number of protons and neutrons that they contain, then nickel-62 is the most tightly bound nucleus, per nucleon.
The following is multiple choice question (with options) to answer.
Which is likeliest to decay? | [
"rock",
"radio waves",
"steel",
"a rhinoceros"
] | D | dead organisms decay |
OpenBookQA | OpenBookQA-4931 | food, nutrition, energy-metabolism
Title: What are the bare minimum nutrients required to survive as a human? I am trying to determine the bare minimum nutritional requirements to survive as a human, ignoring energy (caloric) requirements. Another way to ask this question is: What elements can humans not live without? I am not inquiring solely about what nutrients are needed, but also their approximate amounts.
Imagine pills that a person can take that covers all their base nutritional needs and that after taking this pill the person can eat whatever they want to meet their caloric requirements. Hypothetically, this pill could have some amount (how much?) fat, carbohydrates, protein, fiber, minerals, and vitamins, and the person could subsequently eat any other food to meet their caloric requirements knowing their nutritional needs would already be otherwise met. Lets ignore the possibility of the person suffering from health issues due to eating too much of any specific food to meet their caloric requirements (e.g., taking the magic pills and then eating only butter).
A person in this situation could think "Ok I've got most of my bases covered, now I just need to ingest another 1000 calories of (almost) anything I want).
What nutrients are absolutely necessary for humans to survive indefinitely, and how much of these nutrients are required?
I am hoping for a complete list with approximate amounts (e.g., 20g fat, 20g carbohydrates, 1mg Vitamin X, .05mg Vitamin Y, 10mg mineral X). Essential nutrients include (NutrientsReview):
Water
9 amino acids: histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, tryptophan, threonine, valine
2 fatty acids (alpha linolenic and linoleic acid)
Vitamins: A, B1, B2, B3, B5, B6, folic acid, biotin, B12, C,
D, E and K (and choline, which is considered a vitamin-like substance)
Minerals: calcium, chromium, chloride, copper, iodine, iron,
manganese, molybdenum, phosphorus, potassium, selenium, sodium, zinc
The following is multiple choice question (with options) to answer.
What requires nutrients for survival? | [
"buildings",
"rocks",
"badgers",
"clouds"
] | C | an animal requires nutrients for survival |
OpenBookQA | OpenBookQA-4932 | Hey, thanks for your help guys. For a minute there, I thought that this theoretical person could not safely expect to live to be 82 years old.
9. Jun 16, 2012
### SW VandeCarr
In fact, on a purely probabilistic basis, for any finite time no matter how large, there is a non zero probability that a person would survive that long. So for a sufficiently large population, there would be a theoretic person that would live 100,000 years. This, of course, has no basis in biology.
In terms of the probability of being murdered, the model would not hold for the 100,000 year old person. In terms of the model, probably the best one can do is assume the proportion of causes of death would be constant. The calculation above needs to be corrected for overall survival in terms of death from any cause.
Last edited: Jun 16, 2012
10. Jun 16, 2012
### viraltux
Interesting... but 0.37% is not that small percentage, don't you think? That means, roughly speaking, that a community of around 300 persons can expect that one of them will be murdered.
If you consider that the number of people we know plus acquaintances can easily be around 300 persons that would mean that most 82 year old persons know of someone in their circles who has been murdered. Mmm... that might be an interesting survey.
11. Jun 16, 2012
### SW VandeCarr
As I said in my previous post, this is a misapplication of statistics. You have to consider survival in terms of all cause death. If you just consider the murder rate, then at some point nearly everyone gets murdered.
12. Jun 16, 2012
### moonman239
I know that.
This person will not die until he reaches age 82, if he is not murdered. As mentioned before, this person has a 68% chance of living to be 82.
13. Jun 16, 2012
### D H
Staff Emeritus
The probability of living to 82 per this problem is 99.63%, not 68%. You missed the decimal point on the 0.37%.
14. Jun 16, 2012
### SW VandeCarr
The following is multiple choice question (with options) to answer.
If a living being will make it to adulthood, then the most important thing to it will be | [
"talons",
"mining",
"edibles",
"hotels"
] | C | an animal requires nutrients for survival |
OpenBookQA | OpenBookQA-4933 | meteorology, geomorphology, climatology, atmospheric-circulation
Source Commons Wikipedia.
The cold waters near the ocean surface results in a cool, stable coastal atmosphere. In this region, evaporation from the ocean is reduced and produces extremely low rainfall over land. Precipitation is limited to morning fog and produces some of the driest ecosystems on Earth. The Atacama desert is the best example of such environment with average rainfalls of 15 mm/year (the driest non-polar region). In some areas, they are trying to take advantage of the little moisture the fog (Camanchaca) brings to establish some agricultural zones. The fog droplets are too small (1-40 micrometers) to form water drops and precipitate, so they use fog-catchers to collect moisture from the fog.
Source: newatlas.com
The following is multiple choice question (with options) to answer.
What primarily drives the hydrologic cycle to produce clouds? | [
"a stalking butler who upon the finger rests",
"how soiled the clothing is",
"energy from a gun",
"energy from a central star"
] | D | water absorbs solar energy in the water cycle |
OpenBookQA | OpenBookQA-4934 | zoology
Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft fecal pellets of partially digested food are excreted and generally consumed immediately. Consuming these cecotropes is important for adequate nutritional intake of Vitamin B12. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the feces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to obtain any nutritional value from plants.
Eating garbage and human feces is thought to be one function of dogs during their early domestication, some 12,000 to 15,000 years ago. They served as our first waste management workers, helping to keep the areas around human settlements clean. A study of village dogs in Zimbabwe revealed that feces made up about 25% of the dogs’ overall diet, with human feces making up a large part of that percentage.
Coprophagia
Daily rhythms of food intake and feces reingestion in the degu, an herbivorous Chilean rodent: optimizing digestion through coprophagy
Coprophagia as seen in Thoroughbred Foals
The following is multiple choice question (with options) to answer.
Animals are unable to grow or remain healthy without | [
"proper sustenance",
"ice",
"restaurants",
"socks"
] | A | an animal requires nutrients to grow and heal |
OpenBookQA | OpenBookQA-4935 | quantum-mechanics, visible-light, reflection, optical-materials
Can someone explain me the interaction between the photon and the molecules in case of a reflection on a solid surface with white color?
I am not asking about direction of light, not asking how the photon knows where to go. (This is well explained already by Feynman's QED.) I realized that I got a downvote, which normally means the answer is wrong, while I think it is true. But the OP has updated the question, so I take this as a chance to also update my answer.
Udate
It seems you expect one simply answer why different things in nature appear white, but the truth is there are different reasons for different things.
For example, clouds are white because of Mie scattering, that is scattering of photons on particles (here small water droplets). There is almost no wavelength-dependence of the scattering efficiency in the visible range, so that all wavelengths in the incoming sunlight are scattered with the same probability, and as a result the cloud is white. But notice, the incoming light has to contain all wavelengths for that. During sunset for example, the cloud base is sometimes red because illuminated by the sun, which is red when close to the horizon during sunset (the reason is that blue light is scattered out of the direct beam due to Rayleigh scattering that prefers to scatter blue light and is responsible for the blue sky during the day).
Another white material is milk, which is a liquid. It is also white because of scattering, this time on particles within the milk. But again, you need an illumination of a light source containing all wavelengths to get a white substance. In a green room, a glass if milk will appear greenish of course...
The following is multiple choice question (with options) to answer.
What will reflect the most light | [
"A car tire",
"A bath towel",
"sheet of paper",
"silver spoon"
] | D | shiny things reflect light |
OpenBookQA | OpenBookQA-4936 | temperature, light, heat
Title: Why does sunburn cause fever? Today I found out that sunburns can cause fever.
What I don't understand is how/why? In my understanding fever is the side effect of an immune reaction against an intruder, mainly bacteria (though I admit I can be wrong).
Google searches like "can sunburn cause fever" only bring up that it is possible, but not why. Here is a good article on the topic.
https://www.nlm.nih.gov/medlineplus/ency/article/003227.htm
But it's most likely due to the fact that a sun burn is an actual burn on the skin that can cause inflammation, inflammation can in turn cause fever. Also having a really bad sunburn can open you up more to the possibilities of skin infections. If this happens then once again you might get a fever due to infection. If you really want to find out more on the cause of fever after sunburn you need to examine the pathophysiology of fever and why fever happens. I bet my money on fever due to skin inflammation after a sunburn, I guess the real question would be why does inflammation cause fever since sunburn = skin inflammation
Here is a good article
http://antranik.org/inflammation-and-the-pathophysiology-of-fever/
The following is multiple choice question (with options) to answer.
High temperatures can be caused when which is exposed to heat? | [
"Wire",
"Circuit",
"Cell",
"Conductor"
] | D | if an object is exposed to a source of heat then that conductor may become hot |
OpenBookQA | OpenBookQA-4937 | evolution, zoology
Let's say the environmental challenge for two different kinds of carnivore (let's call them Bogs and Dats) is to catch Mophers. Both Bogs and Dats initially have the same medium-to-short muzzles. Some Bog individuals figure out that they can dig Mophers out of their burrows, and some Dat individuals figure out that they can catch Mophers at night when the Mophers leave their burrows. Both strategies are successful. Some Bogs happen to have longer muzzles than their cousins, and find it turns out that longer muzzles work synergistically with the digging strategy, allowing Bogs to stick their noses into the Mopher burrows to grab escaping Mophers. The resulting fitness advantage results in an increase of the long-muzzle trait in further generations of Bogs. Note that in this scenario it is the adaptive behavioral strategy that creates selective pressure that favors a particular genetic adaptation.
Dats on the other hand, because of their nocturnal hunting strategy, benefit from improved night vision; and long muzzles don't provide any fitness advantage to Dats because Dats don't dig Mophers from their burrows. As long as Bogs and Dats don't hybridize, they will most likely end up with long and short muzzles respectively.
The Waddington effect, also called “Genetic Assimilation”, is somewhat more direct:
An environmental stress causes a proportion of a population to develop one or more abnormal traits, by interfering with embryological development.
If there is a selective pressure in the environment that favors some subset of those traits, individuals whose genetic makeup makes them more likely to develop that subset of traits, those individuals are likely to produce more descendants than other members of the population.
If being “more likely to develop” that subset of traits results from a weakening of genetically determined development controls that would otherwise prevent development of that subset of traits, then the subset of traits can eventually become the normal phenotype.
The following is multiple choice question (with options) to answer.
Animals cope with the differing temperatures in different ways. When its hot out, which animals pant? | [
"seven",
"whales",
"the sun",
"canines"
] | D | panting is when an animal hangs its tongue out of its mouth to adjust to hot temperatures |
OpenBookQA | OpenBookQA-4938 | desert
Title: When was the first not-icy desert formed? For how long have deserts existed and which one would be the first to be created? I'm talking about arid, dry deserts, not the Antarctic or Arctic or any other icy deserts. Deserts have existed since at least the Permian period (299-251 million years ago) when the world's continents had combined into the Pangaea supercontinent. Stretching from pole to pole, this land mass was large enough that portions of its interior received little or no precipitation, according the University of California Museum of Paleontology.
Pangaea broke into smaller land masses which were moved across the surface by tectonic forces, a process that both changed global climate patterns and the climate those continents were exposed to. As a result, current desert regimes date back to no more than 65.5 million years, according to this Encyclopedia Britannica article:
The desert environments of the present are, in geologic terms,
relatively recent in origin. They represent the most extreme result of
the progressive cooling and consequent aridification of global
climates during the Cenozoic Era (65.5 million years ago to the
present), which also led to the development of savannas and scrublands
in the less arid regions near the tropical and temperate margins of
the developing deserts. It has been suggested that many typical modern
desert plant families, particularly those with an Asian centre of
diversity such as the chenopod and tamarisk families, first appeared
in the Miocene (23 to 5.3 million years ago), evolving in the salty,
drying environment of the disappearing Tethys Sea along what is now
the Mediterranean–Central Asian axis.
Which would put the oldest of "modern" desert somewhere in the region of what later became North Africa or South Asia.
The following is multiple choice question (with options) to answer.
deserts are known for having what type of climates? | [
"moderate",
"comfortable",
"freezing",
"scorching"
] | D | a plant requires a specific climate to grow and survive |
OpenBookQA | OpenBookQA-4939 | newtonian-mechanics, forces, rotational-dynamics, friction, free-body-diagram
Title: How does friction stop a car? I'm unable to understand how friction causes motion in cars and also is responsible for stopping them.
When it starts the impending motion of tyres is in the backward direction that's why friction is in the forward direction and the car starts moving.
But when the car engine turns off, the car stops after some time, but the condition of tyres are the same as in the previous case and friction must be in the forward direction. It is not the same friction, but rather the friction between the wheels and the breaking pads (and in general between the rotating parts of the car and their supports.)
The following is multiple choice question (with options) to answer.
When you press on the brakes in a car, because of friction, | [
"it flies",
"coconut",
"speed goes down",
"the speed increases"
] | C | friction causes the speed of an object to decrease |
OpenBookQA | OpenBookQA-4940 | 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.
if a place has experienced fog, what could be responsible? | [
"there has been excess condensed vapor",
"animals are reproducing currently",
"the local deities are angry",
"the water lacks oxygen"
] | A | An example of moisture is water vapor in the atmosphere |
OpenBookQA | OpenBookQA-4941 | thermodynamics, photoelectric-effect, thermal-conductivity, absorption, solar-cells
Title: Possibility of combining photovoltaics and solar thermal energy In a private setting, photovoltaics and solar thermal energy are often harvested on the home's roof and roof area is limited. So, I thought about combining both, i.e. mounting solar collectors underneath solar cells. The rationale behind this is that the solar cells appear almost black and probably heat up considerably under irradiation. So if the collectors are in tight thermal contact to the cells, the water in the collectors might carry away the heat as usable energy, and possibly even increase the lifetime or efficiency of the cells due to the cooling effect (but this is rather engineering and not part of the question). So roof area is exploited twice (in two different wavelength windows). Moreover, if electric energy from the cells exceeds actual consumption and the battery's storage capacity, it might also be used for heating (albeit at a lower total efficiency, of course).
Can the amount of (infrared) radiation that gets absorbed (or possibly transmitted) by solar cells, and which is available as heat at the back side of the cells, be quantified by a rough calculation and either prove or disprove the benefit of such a concept? Does the almost black appearance of the solar cells fool one into thinking that they also absorb in the infrared, although they don't? Temperature of PV panels increases significantly during the day and their conversion efficiency decreases with increasing temperature. I had access to measurements of a PV plant and it showed that the total power production was about the same in August (middle of summer) and October (early fall). Although the days were shorter and there was less solar irradiance in October vs August, the air temperature was significantly lower making PV panels more efficient. For the outside temperature of 35 C, the PV panels can easily reach 70 C!
The following is multiple choice question (with options) to answer.
Solar energy might be used for | [
"the air",
"making pasta",
"feelings",
"time travel"
] | B | solar energy is an inexhaustible resource |
OpenBookQA | OpenBookQA-4942 | search, comparison, efficiency
An uninformed search algorithm performs an exhaustive search. There are several ways of performing such exhaustive search (e.g. breadth-first or depth-first), which are more efficient than others (depending on the search space or problem). Given that they perform an exhaustive search, they tend to explore "uninteresting" parts of the search space. Hence, in practice, they might be more inefficient than informed search algorithms (that is, they might require more time to find the solution).
The following is multiple choice question (with options) to answer.
Which would be considered exhaustible? | [
"solar",
"oil",
"wind",
"water"
] | B | solar energy is an inexhaustible resource |
OpenBookQA | OpenBookQA-4943 | air-pollution
Title: Less pollution: moving hurricane debris to other regions for use, or burning? When a big hurricane hits, it can create debris on the scale of $\mathrm{10^8 yd^3}$. Cities in Florida, Texas, and other affected areas are struggling to hire enough trucks and drivers to pick it up quickly. But aside from that, I noticed many of the areas have started to burn the debris once it starts building up.
Got to wondering... typically mulch comes in modestly pricey, and when free mulch is offered, it often goes quickly.
So assuming a fair portion of debris is mulchable and is of interest to other areas, and that we can acquire typical transportation resources, then we'll set up transfer from collection sites to those other regions rather than burning it. What would be the net pollution result?
If removed for mulch and such: trucking pollution + decomposition (- trees saved locally??)
If burned: the burning pollution.
Obviously it's about approximation rather than exacts, it's probably hard to appraise the different byproducts from burning versus decomposition, and a lot probably depends upon the way it is burned. But as a whole, can we get a rough estimate of comparable quantities/damage done... is it less pollution/damage even to truck it an average of 3000 miles? 1000 miles? 100 miles? 10 miles? Should it be burned on the spot (if done safely)? Would think there's got to be some way to get a very rough idea.
Certainly the best option if viable might be leaving it in place to decompose. But considering how upset people are getting at having debris around these parts a month later, exclude that option from the possibilities.
Trucking or burning, how do they compare? As the question was changed, my answer attempts to evaluate only the difference between burning and transporting. Please correct my values if my quickly found sources are inaccurate or you find more representing. I know there is quite a few unwritten assumptions that simplify this problem.
The following is multiple choice question (with options) to answer.
Which likely causes the most waste? | [
"a twinkie factory",
"sustainable fisheries",
"solar panels",
"a wind farm"
] | A | processes sometimes produce waste products |
OpenBookQA | OpenBookQA-4944 | sun
Title: Is there an instance where the sun sets or rises partly, then return back? I am reading Longest Sunset from XKCD. At first, I've thought that he mentions these phenomena just for fun, but it turns out to me that it might happens, based on the level of somewhat seriousness that I perceive from his writing. He doesn't talk about that in detail.
For the sunset:
Sunset starts the instant the Sun touches the horizon, and ends when it disappears completely. If the Sun touches the horizon and then lifts back up, the sunset is disqualified.
I'm not sure if the sunset is disqualified is because it happens, but we don't count it, or because he's just making fun. But I can't prove that this cannot happen. The more we head to the poles, the shorter the night is. Ultimately there will be a point that the sun still sets, but not completely, right?
For the sunrise:
For the purposes of our question, this is not a sunset:
The phrase for our purposes strengthen my doubt that he is being serious. The logic is the same above.
But these two illustrations are in the series of other apparently amusing ones, which are the sun as the cell in division, or as the egg in hatching (if you read the book, you will see this effect stronger).
So, is there an instance where the sun sets or rises partly, then return back? Yes, such sunrises happens every year at the beginning and end of the polar nights at high latitudes. One can have a few days with a glimpse of the sun but disqualified sunsets and sunrises.
Sunsets occur at the end of the midnight sun period by the end of the summer, the first sunset is not complete.
Sun at it's highest elevation at midday. (To be honest, the picture might be taken the day after the first sunrise, as some mountains are hiding the horizon.)
Here is e.g. an article from Svalbardsposten, the northernmost newspaper in the world, reporting of the first rays of sunlight after the polar night and some pictures from the last sunrise/sunset before the polar night in northern Sweden.
The same occurs at the southern polar circle and south thereof, unless it's cloudy...
Update: here is a great time laps from Davis Station in the Vestfold Hills showing exactly what you asked about: Mid winter
The following is multiple choice question (with options) to answer.
Sunrises in January are | [
"late",
"green",
"old",
"early"
] | A | when the season changes , the amount of daylight will change |
OpenBookQA | OpenBookQA-4945 | Shanonhaliwell April 8th, 2018 03:31 PM
Quote:
Originally Posted by romsek (Post 591335) outstanding, you seem to be getting the hang of things.
Thanks to you, I was able to do it.
All times are GMT -8. The time now is 12:30 AM.
The following is multiple choice question (with options) to answer.
There's more time to go for walks when | [
"it's winter",
"owls are hunting",
"it's summer",
"there's an evacuation"
] | C | when the season changes , the amount of daylight will change |
OpenBookQA | OpenBookQA-4946 | species-identification
Title: What is this (water-loving) bug? For some time we've been finding these little fellows in our apartment:
They seem harmless enough, but finding them is a bit... annoying. I found the fellow above in the bathtub, and it's not uncommon to find more than one.
Unfortunately, some started to appear near the kitchen sink as well. Or outside of the bathroom on the floor (at least that's where we noticed them).
I think this thing prefers darkness over light, and seems to be drawn towards wet places or just water. These critters are also surprisingly fast.
What is it? Should we be concerned about a pest problem, or is this just a minor, unwelcome guest?
PS. We live in Poland. It is a Lepisma saccharina or silverfish.
It is rather common and yes, it's harmless.
The following is multiple choice question (with options) to answer.
What lives in their habitat? | [
"dahlias",
"rocks",
"lakes",
"shoes"
] | A | living things live in their habitat |
OpenBookQA | OpenBookQA-4947 | botany, ecology, energy
Title: Why do plants create enough energy for the entire ecosystem? In my environmental class, we were recently learning about the $10\%$ law that basically says only $10\%$ of the energy goes from one trophic level to the next.
This got me thinking about why energy flows from one level to the next. Specifically, why do plants create enough energy for the entire ecosystem? Wouldn't they do fine without us, and wouldn't that save them the work of creating all that excess energy? Plants collect energy for themselves via photosynthesis, not for others.
It is used for it's own growth and survival.
It's energy is then redistributed to other organisms when either the plant dies and decomposes or when it is consumed. Many organism cannot collect their energy like plants do, and thus must feed on organisms (like plants) that are able to collect and store energy. This is in many cases detrimental to the plant (it should be intuitive why being eaten might be bad), and many, many plants do have traits to discourage other organisms from eating them (plants with toxins, thorns, etc.).
The following is multiple choice question (with options) to answer.
All living things do what? | [
"swim",
"develop",
"fly",
"shrink"
] | B | all living things grow |
OpenBookQA | OpenBookQA-4948 | entomology
Title: What is the name of this tiny creature? It looks like a tiny piece of moving cotton? By chance, I saw this tiny insect on my bag a few days ago in Sydney. Am I the first person who has pinpointed this animal?! If not can you please let me know its name? From your image, it looks like it might be a woolly aphid. I just did a bit of cursory research, and it looks like they're often described as floating pieces of fluff, that seem to wander instead of directly heading somewhere. The fluff on their back is actually wax produced as a defense mechanism from predators and the like. I hope this is what you were looking for!
The following is multiple choice question (with options) to answer.
A skunk produces a bad what? | [
"heat",
"smeller perception",
"cold",
"color"
] | B | a skunk produces a bad odor |
OpenBookQA | OpenBookQA-4949 | 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.
Food is a source of energy for what? | [
"anteaters",
"sand",
"water",
"plastic"
] | A | food is a source of energy for animals |
OpenBookQA | OpenBookQA-4950 | 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.
food is a source of energy for what? | [
"waterfalls",
"fires",
"grass snakes",
"mountains"
] | C | food is a source of energy for animals |
OpenBookQA | OpenBookQA-4951 | meteorology, mesoscale-meteorology
In a sense, the fact pressure at one elevation induces changes\motion in another elevation maybe shouldn't seem any less weird than the fact that a low-level low pressure system can affect the wind and weather hundreds of miles away from it horizontally. This isn't spooky action at a distance, this is a continuous fluid where changes to one part of it causes impacts on another part.
The following is multiple choice question (with options) to answer.
Heavy atmospheric movement is desirable if you have | [
"paper plates",
"perfect hair",
"a wind turbine",
"a badminton match"
] | C | windy means high wind speeds |
OpenBookQA | OpenBookQA-4952 | - Origin at the center of the egg. Included is an example solving the heat equation on a bar of length L but instead on a thin circular ring. We are adding to the equation found in the 2-D heat equation in cylindrical coordinates, starting with the following definition::= (,) × (,) × (,). Semi-analytical solutions are obtained for transient and steady-state heat conduction. We Assume I) Eggs Are Perfectly Spherical With Radius R (ii)the 'material' Of An Egg Is Homogeneous, Meaning That The Shell, White, And Yolk Have The Same Thermal Conductivity. Rectangular Coordinates. A partial differential equation (or briefly a PDE) is a mathematical equation that involves two or more independent variables, an unknown function (dependent on those variables), and partial derivatives of the unknown function with respect to the independent variables. This dual theoretical-experimental method is applicable to rubber, various other polymeric materials. general heat conduction equation in spherical coordinates - Duration: 17:44. Our solution method, though, worked on first order differential equations. The functional for for large is given. Pennes' bioheat equation was used to model heat transfer in each region and the set of equations was coupled through boundary condi-tions at the interfaces. Conduction Heat Transfer: Conduction is the transfer of energy from a more energetic to the less energetic particles of substances due to interactions between the particles. 4, Myint-U & Debnath §2. The mathematical complexity behind such an equation can be intractable by analytical means. Based on the authors’ own research and classroom experience, this book contains two parts, in Part (I): the 1D cylindrical coordinates, non-linear partial differential equation of transient heat conduction through a temperature dependent thermal conductivity of a thermal insulation material is solved analytically using Kirchhoff’s. 2, 2017 DOI: 10. The heat transfer problems in the coupled conductive-radiative formulation are fundamentally nonlinear. 1: Heat conduction through a large plane wall. However, I want to solve the equations in spherical coordinates. 2 Numerical solution for 1D advection equation with initial conditions of a box pulse with a constant wave speed using the spectral method in (a) and nite di erence method in (b) 88. the course, we will study particular solutions to the spherical wave equation, when we solve the nonhomogeneous version of the
The following is multiple choice question (with options) to answer.
Which of the following is likely to change an egg's shape and mass? | [
"Placing it on a pillow",
"Dropping it from a building",
"Leaving it in a carton",
"Holding it in your hand"
] | B | breaking down an object changes that object 's shape and mass |
OpenBookQA | OpenBookQA-4953 | materials
The image is a modified version of an image found at www.geology.um.maine.edu. Original credit: Passchier and Trouw, pg 33 (2005).
The following is multiple choice question (with options) to answer.
A bulldozer alters the area of | [
"skyscrapers",
"the stock market",
"air",
"water"
] | A | breaking down an object changes that object 's shape and mass |
OpenBookQA | OpenBookQA-4954 | evolution, biochemistry, plant-physiology, plant-anatomy, life
Title: Plants without bacteria? is it theoretically possible? I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But it is a natural way.
But is it possible to have a world with plants (without mammals or microorganisms and without bacteria) that could exist in the long term. Saying the atmosphere of these world has already enough nitrogen, oxygen and CO2, and of course there is water.
What could break this artificially created world with such conditions (say the world created not from low-level living structures)?
Could bacteria emerge in the world? This is the sort of question that should be considered from more than one perspective. Since this is speculation, take it as a given that there is a lot of 'what if' here.
I doubt most animals and plants can do entirely without bacteria - as you say most of the essential nutrients come from bacteria, who fix nitrogen. If only plants were left on earth, eventually the plants would use up all the nitrogen and they would have to find a way to fix more.
Can bacteria emerge from just a world of plants? I don't think viruses arise spontaneously, but since genomes often have viruses embedded in them, over the course of a billion years or so, its possible since bacteria and viruses continue to be impressed upon our genomes. Would it happen in time? Most would be skeptical whether that timing could work out.
In practice it would be hard to create a world like this. I would be interested to see whether you could sterilize the microorganisms off of seeds without killing the plant for instance. If you're asking about a small sterile environment with only plants, you could do it by adding the nutrients the plants need and giving them sunlight. Such self sustaining systems have been made with cyanobacteria and i'd be surprised if plants could not be included. But these are closed systems and judged by limited amounts of time, so whether this is an answer to your question is not clear. Here it looks like some water plants and fish have been done. If there was a plant that created CO₂ at an adequate rate its possible.
The following is multiple choice question (with options) to answer.
An organism that can survive without the help of other cells is | [
"Brewer's yeast",
"air",
"sand",
"sugar"
] | A | a single-cell organism can survive without the help of other cells |
OpenBookQA | OpenBookQA-4955 | evolution, zoology
Let's say the environmental challenge for two different kinds of carnivore (let's call them Bogs and Dats) is to catch Mophers. Both Bogs and Dats initially have the same medium-to-short muzzles. Some Bog individuals figure out that they can dig Mophers out of their burrows, and some Dat individuals figure out that they can catch Mophers at night when the Mophers leave their burrows. Both strategies are successful. Some Bogs happen to have longer muzzles than their cousins, and find it turns out that longer muzzles work synergistically with the digging strategy, allowing Bogs to stick their noses into the Mopher burrows to grab escaping Mophers. The resulting fitness advantage results in an increase of the long-muzzle trait in further generations of Bogs. Note that in this scenario it is the adaptive behavioral strategy that creates selective pressure that favors a particular genetic adaptation.
Dats on the other hand, because of their nocturnal hunting strategy, benefit from improved night vision; and long muzzles don't provide any fitness advantage to Dats because Dats don't dig Mophers from their burrows. As long as Bogs and Dats don't hybridize, they will most likely end up with long and short muzzles respectively.
The Waddington effect, also called “Genetic Assimilation”, is somewhat more direct:
An environmental stress causes a proportion of a population to develop one or more abnormal traits, by interfering with embryological development.
If there is a selective pressure in the environment that favors some subset of those traits, individuals whose genetic makeup makes them more likely to develop that subset of traits, those individuals are likely to produce more descendants than other members of the population.
If being “more likely to develop” that subset of traits results from a weakening of genetically determined development controls that would otherwise prevent development of that subset of traits, then the subset of traits can eventually become the normal phenotype.
The following is multiple choice question (with options) to answer.
The nimbleness of this animal is a key adaption that allows it to escape attacks from predators: | [
"the praying mantis",
"the antelope",
"the butterfly",
"the sloth"
] | B | adaptation is when an organism develops a trait over time for survival |
OpenBookQA | OpenBookQA-4956 | evolution, ornithology, palaeontology
One thing those many, many bird and proto-bird fossils also made clear is that the traits of modern birds (feathers, wings, toothless beaks, etc) didn't evolve in a simple line from non-bird to bird. Many of those traits evolved convergently in several lineages, were lost in some, maybe regained in others, and feathers in particular turn out to be a widespread dinosaur feature that cannot be considered a uniquely bird trait anymore (unless we want to call T-rexes "birds"). Still, saying "beaks evolved several times" or "feathers evolved several times" doesn't mean that birds, let alone modern birds, evolved from several different ancestors. It can mean that the common ancestor of birds had lots of variously bird-like more-or-less distant cousins living around the same time.
The following is multiple choice question (with options) to answer.
Birds will have different kinds of beaks depending on the | [
"organisms they hunt",
"computer",
"groceries",
"seven"
] | A | a beak is used for catching prey by some birds |
OpenBookQA | OpenBookQA-4957 | feature a number of tools to solve geometry problems. Each part is called semi circle. A rectangle is one of the many fundamental shapes you'll see in math. Round your answer to the nearest hundredth. A square has sides of length 12 cm. To make the pies, roll the pastry on a floured surface into a large rectangle, about 12 inches by 24-plus inches. Learn how to calculate perimeter and area for various shapes. The distance around the outside of a semicircle is generally called its perimeter. It is evident that if we make a large number of cuts, the figure formed will approximate a rectangle whose length is equal to one-half of the circumference and whose width is equal to the radius. Fold the entire piece of fabric in half to create a large square. Area of a circle intuition. Requires knowledge of Conic Sections. make up Remember, by o shape. Creating a design with pavers requires planning. Repeat the same method the other side. where r is the radius of the circle. The word ‘area’ stands for the space occupied by a flat object or figure. To get the area of the triangle portion, I subtract the area of the sector of the circle with the area of the triangle of that portion multiplied by 2 (since there are essentially two triangles). Draw and cut out the wing shape from the flap and insert into the slit. 1165 1225 112. Calculations at a semicircle. 28 square cm. asked by ian on August 29, 2016. How to Find the Area of a Semicircle To find the area of a semi-circle, you need to know the formula for the area of a circle. Semi-circles are drawn on and as diameters. Determine the diameter of the circle you intend to make. 4 in L, Base 6in - 4694841. in Get all GUIDE and Sample Paper PDFs by whatsapp from +91 89056 29969 Page 251 16. Practice: Area of a circle. In the article below, we provide the semicircle definition and explain how to find the perimeter and area of a semicircle. What is the objective function in terms of the base of the rectangle, x? (Type an expression. The Gimp provides the Rectangle, Ellipse and Lasso selection tools to help you cut out specific parts of a photo or illustration to keep, eliminate or edit. Area
The following is multiple choice question (with options) to answer.
Harriet wants to know the area of a rectangular sheet of paper. Its size is unknown to her. Which one of these will be the only tool that she needs? | [
"a ruler",
"a compass",
"a calculator",
"a protractor"
] | A | a ruler is used for measuring the length of an object |
SciQ | SciQ-1 | food, biotechnology
Title: How to increase the shelf life of yogurt without refrigeration? When we make yogurt at home and do not refrigerate it, it will become sour because of conversion of lactose into lactic acid by Lactobacillus bacteria, but this does not happen in case of Nestle's yogurt or any other brand until it remains air tight.
I wonder though bacteria is still present in it and continue to convert lactose into lactic acid then why does not packed yogurt becomes sour? How these companies increase the shelf life of yogurt..? This article gives an excellent review on yogurt manufacturing, but to summarize:
-Raw milk goes through centrifugation to remove somatic cells and other solid impurities.
-Thermalization is conducted at "60–69 °C for 20–30 s, aiming at the killing of many vegetative microorganisms and the partial inactivation of some enzymes."
After this point, the milk may be inoculated with lactic acid bacteria or other microfloras.
-Then, standardization occurs which for milk refers to the standardization of fat and solid-non-fat content (SNF). This in short affects the fermentation process ("an increase of SNF increases the duration of the fermentation process").
-The next step is homogenization, which prevents milk fat from rising to the top of the liquid. This has an effect on the stability of the emulsion.
-I think this step is where "sterility" comes into play, "heat treatment of milk reduces the number of pathogenic microorganisms to safe limits for the consumer’s health. Various heat treatments can be applied, which are classified based on the duration and the temperature. The most common are known as thermalization, low and high pasteurization, sterilization and UHT (Ultra Heat Treatment)." The review goes into more detail about each type and what they eliminate or don't eliminate (spores, vegetative bacteria, etc.).
The following is multiple choice question (with options) to answer.
What type of organism is commonly used in preparation of foods such as cheese and yogurt? | [
"protozoa",
"gymnosperms",
"mesophilic organisms",
"viruses"
] | C | Mesophiles grow best in moderate temperature, typically between 25°C and 40°C (77°F and 104°F). Mesophiles are often found living in or on the bodies of humans or other animals. The optimal growth temperature of many pathogenic mesophiles is 37°C (98°F), the normal human body temperature. Mesophilic organisms have important uses in food preparation, including cheese, yogurt, beer and wine. |
SciQ | SciQ-2 | fluid-dynamics, reference-frames, atmospheric-science, coriolis-effect, meteorology
Title: What determines handedness of wind circulation around pressure extrema in the atmosphere? I'm reading a textbook (Atmospheric Science - An Introductory Survey 2nd ed, John M. Wallace • Peter V. Hobbs) which states (p14):
The winds observed in the Earth’s atmosphere closely parallel the isobars. In the northern hemisphere, lower pressure lies to the left of the wind (looking downstream) and higher pressure to the right. It follows that air circulates counter-clockwise around lows and clockwise around highs.
What is the reasoning here - I can't find a reason for handedness in the assumptions. In the northern hemisphere the Coriolis effect tends to deflect a moving mass to the right. (Consider your velocity relative to the surface of the earth when going to the north or south.) Air tends to flow toward a region of low pressure. If is deflected to the right it ends up going counter-clockwise around the low (and clockwise while leaving a high).
The following is multiple choice question (with options) to answer.
What phenomenon makes global winds blow northeast to southwest or the reverse in the northern hemisphere and northwest to southeast or the reverse in the southern hemisphere? | [
"muon effect",
"tropical effect",
"coriolis effect",
"centrifugal effect"
] | C | Without Coriolis Effect the global winds would blow north to south or south to north. But Coriolis makes them blow northeast to southwest or the reverse in the Northern Hemisphere. The winds blow northwest to southeast or the reverse in the southern hemisphere. |
SciQ | SciQ-3 | thermodynamics, phase-transition, metals, liquid-state
A correct microscopic picture of the melting transition
The different behavior of many observables characterizes crystalline solids and liquids. However, we should not forget that amorphous solids exist, blurring many possible characterizations of the transition based on the concept of spatial order or, on average static quantities. Dynamical properties remain a much clearer indication of the passage from a solid to a liquid phase. In particular, the apparently simple concept that liquid flow and solid don't is a good starting concept to build intuition on the melting process.
Here, I'll try to underline a few (correct) ideas one can connect to the fact that liquids flow.
The following is multiple choice question (with options) to answer.
Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always what? | [
"reactive",
"unbalanced",
"endothermic",
"exothermic"
] | D | Summary Changes of state are examples of phase changes, or phase transitions. All phase changes are accompanied by changes in the energy of a system. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) areendothermic. Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always exothermic. The conversion of a solid to a liquid is called fusion (or melting). The energy required to melt 1 mol of a substance is its enthalpy of fusion (ΔHfus). The energy change required to vaporize 1 mol of a substance is the enthalpy of vaporization (ΔHvap). The direct conversion of a solid to a gas is sublimation. The amount of energy needed to sublime 1 mol of a substance is its enthalpy of sublimation (ΔHsub) and is the sum of the enthalpies of fusion and vaporization. Plots of the temperature of a substance versus heat added or versus heating time at a constant rate of heating are calledheating curves. Heating curves relate temperature changes to phase transitions. A superheated liquid, a liquid at a temperature and pressure at which it should be a gas, is not stable. A cooling curve is not exactly the reverse of the heating curve because many liquids do not freeze at the expected temperature. Instead, they form a supercooled liquid, a metastable liquid phase that exists below the normal melting point. Supercooled liquids usually crystallize on standing, or adding a seed crystal of the same or another substance can induce crystallization. |
SciQ | SciQ-4 | time, radiation
Title: What isotope has the shortest half life? Question:
What isotope has the shortest half life? The question is ill-posed.
To begin it should be "*What isotope has the..." and even then the answer is "We don't really know, as there are some we have produced too few times to have an accurate measure for but they sure don't live long." Looking at the low-mass end of the periodic table I find some described in terms of the linewidth---which means really short.
Isotopes with halflives measured in 10s of seconds have been put to use from time to time. And the shortlived low-mass isotopes are useful in calibrating underground neutrino detectors.
The following is multiple choice question (with options) to answer.
What is the least dangerous radioactive decay? | [
"zeta decay",
"gamma decay",
"beta decay",
"alpha decay"
] | D | All radioactive decay is dangerous to living things, but alpha decay is the least dangerous. |
SciQ | SciQ-5 | volcanology, earthquakes, geothermal-heat, volcanic-hazard
Questions about the relation between human activity or developments and active Hawaiian volcanoes usually are raised during eruptions. These concerns often regard the location of an industrial development, like a geothermal power generation facility, on a volcano (for example, Big Island Video News, 2019; Firozi, 2018). Since the 2018 eruption, the topic of whether commercial developments not only caused the eruption to occur in Kīlaueaʻs lower East Rift Zone (LERZ), but also caused it to erupt with a higher-than-normal rate has been a subject of public discussion.
They examined the past activity of the volcano (location, volume, frequency... of past eruptions), and compared it to the 2018 eruption, concluding (emphasis added):
There are no obvious effects of human activity on eruptions of Kīlauea volcano. There have been no significant changes due to human activity in patterns or trends of deformation or seismicity in the lower East Rift Zone in the last 35–50 years (before and during geothermal operations). The frequency and intensity of eruptions are variable, but it would be difficult to demonstrate a definitive change due to human activity. [...] We find no evidence to support claims that human activity triggered or influenced the 2018 lower East Rift Zone eruption. The 2018 eruption was caused by injection of magma downrift from Puʻu ʻŌʻō and the summit of Kīlauea. The event fits a pattern of activity that has occurred many times previously on the East Rift Zone and is within the range of normal behavior for Kīlauea Volcano.
So again the answer is "no", but the USGS is a source a bit more authoritative than me! :)
The following is multiple choice question (with options) to answer.
Kilauea in hawaii is the world’s most continuously active volcano. very active volcanoes characteristically eject red-hot rocks and lava rather than this? | [
"carbon and smog",
"greenhouse gases",
"magma",
"smoke and ash"
] | D | Example 3.5 Calculating Projectile Motion: Hot Rock Projectile Kilauea in Hawaii is the world’s most continuously active volcano. Very active volcanoes characteristically eject red-hot rocks and lava rather than smoke and ash. Suppose a large rock is ejected from the volcano with a speed of 25.0 m/s and at an angle 35.0º above the horizontal, as shown in Figure 3.40. The rock strikes the side of the volcano at an altitude 20.0 m lower than its starting point. (a) Calculate the time it takes the rock to follow this path. (b) What are the magnitude and direction of the rock’s velocity at impact?. |
SciQ | SciQ-6 | asteroids, meteor, meteorite, meteoroid, chicxulub
Title: Which kind of celestial body killed dinosaurs? Well, the internet lies a lot, so there's so much information mixed with misinformation...
Some sources call what killed the dinosaurs an asteroid and others a meteor.
Is there any consensus on this?
By definition, an asteroid would never collide with Earth, because the moment it entered the atmosphere it would be called a meteor, or am I wrong? Or else, by the size of the celestial body and/or the speed with which it entered the atmosphere and/or the little impact that the atmosphere had in this collision, does it say that it was an asteroid that collided with the Earth, with no mention to meteor/meteorite therms?
Also, was it really an asteroid that started to enter the collision route with Earth, and not a meteoroid from a bigger celestial body?
Finally, if that body was so great that collided with ground, why is it not called meteorite?
Or is the total confusion in internet because there is no consensus in science community about that past event, and there are only a lot of hypothesis and a few evidences and theory? Definitions:
A meteoroid is a celestial object larger than an grain of dust and smaller than 1 meter in diameter.
An asteroid is a celestial object larger than 1 meter in diameter.
A meteor is a streak of light caused by superheated air as a meteoroid enters the atmosphere.
A meteor is NOT the space rock which causes the meteor: it is not any type of solid object. So the impactor which killed the dinosaurs was an asteroid which might possibly have made a meteor appear in the sky before exploding with the force of millions of atomic bombs.
The following is multiple choice question (with options) to answer.
When a meteoroid reaches earth, what is the remaining object called? | [
"meteorite",
"meteor",
"comet",
"orbit"
] | A | Meteoroids are smaller than asteroids, ranging from the size of boulders to the size of sand grains. When meteoroids enter Earth’s atmosphere, they vaporize, creating a trail of glowing gas called a meteor. If any of the meteoroid reaches Earth, the remaining object is called a meteorite. |
SciQ | SciQ-7 | inorganic-chemistry, redox, combustion
As M. Farooq pointed out a combustion reaction happens quickly, producing heat, and usually light and fire. For example, lets look at combustion reaction of an alkene (a hydrocarbon). If it is a complete combustion, the fire have a blue flame:
$$\ce{C_nH_{2n} + $\frac{3n}{2}$ O2 -> nCO2 + n H2O}$$
If it is a partial combustion, it can have a multiple $\ce{C}$ compounds as products, and have a yellow flame due to presence of elemental $\ce{C}$:
$$\ce{C_nH_{2n} + x O2 -> m C + p CO + $(n-m-p)$CO2 + n H2O}$$
where $x = \frac{2(n-p-m) +p}{2} = \frac{2n-2p-2m +p}{2} = \frac{2n-p-2m)}{2}$. In your reaction would not produce fire and it didn't use either oxygen or other oxidants ($\ce{CuO}$ is not that type of oxidant). It is true that the reaction is a redox reaction.
The following is multiple choice question (with options) to answer.
What kind of a reaction occurs when a substance reacts quickly with oxygen? | [
"combustion reaction",
"invention reaction",
"Fluid Reaction",
"nitrogen reaction"
] | A | A combustion reaction occurs when a substance reacts quickly with oxygen (O 2 ). For example, in the Figure below , charcoal is combining with oxygen. Combustion is commonly called burning, and the substance that burns is usually referred to as fuel. The products of a complete combustion reaction include carbon dioxide (CO 2 ) and water vapor (H 2 O). The reaction typically gives off heat and light as well. The general equation for a complete combustion reaction is:. |
SciQ | SciQ-8 | evolution, species, molecular-evolution, species-distribution, macroevolution
Lalage leucopygialis, L. nigra, and L. sueurii: Species of triller birds that coexist on Sulawesi Island.
The existence of ring species like this can, as biologist Ernst Mayr puts it, illustrate "how new species can arise through 'circular overlap', without interruption of gene flow through intervening populations…" and offers proof of speciation through a method other than allopatric speciation: speciation that happens when two populations of the same species become isolated from each other due to geographic changes.
The following is multiple choice question (with options) to answer.
Organisms categorized by what species descriptor demonstrate a version of allopatric speciation and have limited regions of overlap with one another, but where they overlap they interbreed successfully?. | [
"fitting species",
"surface species",
"species complex",
"ring species"
] | D | Ring species Ring species demonstrate a version of allopatric speciation. Imagine populations of the species A. Over the geographic range of A there exist a number of subpopulations. These subpopulations (A1 to A5) and (Aa to Ae) have limited regions of overlap with one another but where they overlap they interbreed successfully. But populations A5 and Ae no longer interbreed successfully – are these populations separate species? In this case, there is no clear-cut answer, but it is likely that in the link between the various populations will be broken and one or more species may form in the future. Consider the black bear Ursus americanus. Originally distributed across all of North America, its distribution is now much more fragmented. Isolated populations are free to adapt to their own particular environments and migration between populations is limited. Clearly the environment in Florida is different from that in Mexico, Alaska, or Newfoundland. Different environments will favor different adaptations. If, over time, these populations were to come back into contact with one another, they might or might not be able to interbreed successfully - reproductive isolation may occur and one species may become many. |
SciQ | SciQ-9 | particle-physics, nuclear-physics, atomic-physics, radiation, radioactivity
Title: What is the importance of excited states in the emission of gamma radiation during alpha decay? Let's suppose that during a hypothetical alpha decay of a nucleus X, has two excited states (such as 2.3 mEV and 0.9 mEV) are respectively fed.
The question arises here: what would would be the energy of the gamma rays that could be emitted?
My work: Would the alpha decay energy into the superior excited state (2.3 mEV) be equal to the gamma ray de-exitation from the superior excited state to the inferior excited state (0.9 mEV)?
And then,will the energy when the inferior excited state falls into the ground state be equal to 0.9 mEV?
So, I´m not sure if what we are looking for is a distribution of the energies emitted during this decay, which could vary, OR the total energy of the gamma rays that were emitted, which would be a sum of Excited State 2 -> Excited State 1 and Excited State 1 -> Ground State (1,4 + 0,9= 2,3 mEV)
Thanks for your help. Here's a level scheme for cobalt-60 which I decorated recently to answer another question about gamma emission. The 99.9% decay pathway is highlighted. This is a beta emitter instead of an alpha emitter, but I don't think that's a big deal for your question.
The following is multiple choice question (with options) to answer.
Alpha emission is a type of what? | [
"light",
"heat",
"radioactivity",
"radiation"
] | C | One type of radioactivity is alpha emission. What is an alpha particle? What happens to an alpha particle after it is emitted from an unstable nucleus?. |
SciQ | SciQ-10 | evolution, botany, proteins
tl;dr: the egg contains more proteins than the seed because the chicken that made the egg ate a whole lot of seeds, and all the protein in those seeds ended up concentrated in that one egg.
EDIT: running into this much later I realized I missed a pretty vital half of the question, because there is a difference between fruits and seeds. The difference is the following: nitrogen is precious for plants so they'll try and use it for very important things. Seeds are very important to the plant, so while a seed has less protein than an egg it will still have lots of protein by plant standards. Fruits now, that's another story. Like the sugary nectar, fruits are a bribe for animals, a bit of food offered to them so that they'll spread the plant's seeds. And like with the sugary nectar, the plant has every incentive to pack that bribe full of cheap carbohydrates and as few precious proteins as it can manage.
The following is multiple choice question (with options) to answer.
What is the stored food in a seed called? | [
"endosperm",
"membrane",
"pollin",
"larval"
] | A | The stored food in a seed is called endosperm . It nourishes the embryo until it can start making food on its own. |
SciQ | SciQ-11 | acid-base, reaction-mechanism, redox
There is a rather interesting exception though: zinc strongly breaks the trend, being far easier to oxidize than copper, the element before it, even though zinc has a much higher ionization energy, clearly indicating its electrons are held tighter (cadmium also exhibits this anomaly, to a milder extent). What gives? The thing is that the tendency for a metal to oxidize is the result of several combined factors, one of which is also how strongly bound the solid metal is in the first place. If a metal contains atoms which are strongly bonded to each other, then oxidation tends to be more unfavourable as it would require these bonds to break. When comparing copper and zinc, it is clear that the latter has far weaker metallic bonding in the solid (their melting/boiling points are $1360\ \rm{K}$ / $2835\ \rm{K}$ and $695\ \rm{K}$ / $1180\ \rm{K}$, respectively). Thus, if you include the energy necessary to separate the atoms from the solid before ionizing them, it turns out that the process is easier for zinc than copper.
Comparing different rows of the transition metals is a bit less clear, in part because not all elements have ions of the same charge which can be directly compared. The general tendency is that the metals become tougher to oxidize as you go down the rows. For the transition metals in the sixth and seventh period this is probably a consequence of lanthanide/actinide contraction and relativistic effects, which decrease the energy of the valence $ns$ orbitals.
Now for some other elements. Magnesium is very reactive towards acids because it is both a metal containing relatively weak bonds and because its ionization energy is comparatively low, being an alkaline earth element. For tin, the metallic bonding is not weak, but its ionization energy is not too high, so it will oxidize in acids, though not as strongly. Lead is somewhat less reactive to acids, possibly because its oxidation tends to stop at +2 instead of tin's +4, creating a significantly softer cation which isn't as well solvated by water.
The following is multiple choice question (with options) to answer.
Zinc is more easily oxidized than iron because zinc has a lower reduction potential. since zinc has a lower reduction potential, it is a more what? | [
"usually metal",
"Trap metal",
"much metal",
"active metal"
] | D | One way to keep iron from corroding is to keep it painted. The layer of paint prevents the water and oxygen necessary for rust formation from coming into contact with the iron. As long as the paint remains intact, the iron is protected from corrosion. Other strategies include alloying the iron with other metals. For example, stainless steel is mostly iron with a bit of chromium. The chromium tends to collect near the surface, where it forms an oxide layer that protects the iron. Zinc-plated or galvanized iron uses a different strategy. Zinc is more easily oxidized than iron because zinc has a lower reduction potential. Since zinc has a lower reduction potential, it is a more active metal. Thus, even if the zinc coating is scratched, the zinc will still oxidize before the iron. This suggests that this approach should work with other active metals. Another important way to protect metal is to make it the cathode in a galvanic cell. This is cathodic protection and can be used for metals other than just iron. For example, the rusting of underground iron storage tanks and pipes can be prevented or greatly reduced by connecting them to a more active metal such as zinc or magnesium (Figure 17.18). This is also used to protect the metal parts in water heaters. The more active metals (lower reduction potential) are called sacrificial anodes because as they get used up as they corrode (oxidize) at the anode. The metal being protected serves as the cathode, and so does not oxidize (corrode). When the anodes are properly monitored and periodically replaced, the useful lifetime of the iron storage tank can be greatly extended. |
SciQ | SciQ-12 | molecular-biology, proteins, genetics, learning
Title: How do proteins and genes participate in learning? I am a computer scientist that studies biology and bioinformatics.
In the last weeks, I have been trying to study new research directions, and I would like to deepen my knowledge on the role and behavior of genes and proteins in learning.
By learning, I mean the human process: the information I is absent at time T, and present at time T+1.
I would like to study more this problem, and I am wondering: how do proteins and genes behave during learning?
I have read that proteins that participate in learning are called marker proteins. Is it true? Which role do they have?
Where could I find some resources to study this fascinating problem?
Thank you very much! The storage of memories in cells is rarely thought of on the protein level of the cell. Cells are usually given a developmental state, but no memory. A cell may become a liver cell, cancerous, or diabetic, but this is not memory, but a physiological change in the cell which is usually not reversible to a previous state.
For example cancer treatments are entirely focused on identifying the cancerous cells and killing them. Internally the genomes of cancer cells often have deletions and duplications. They are cancerous, they have not learned to be cancerous. Though not as dramatic, it is now thought that cellular differentiation which creates different types of cells is heavily influenced by epigenetic modification of the genome; the DNA is marked by methyl groups which dictates the state of the cell by modifying the gene. This is mediated by proteins for sure, but is quite complex and not well understood at this time. Epigenetic markers can even change gene behavior between generations of offspring as well, though that is not usually called memory.
How is information stored in the brain? This is thought to be reflected in the organization of the neurons in the brain. There are many kinds of neurons. They can be distinguished by the sorts of axons and dendrites that emanate from the cell body. They can also be distinguished by the chemical variety of neurotransmitter they use (there are a score of different molecules). So to a great extent the type of cell and the specific proteins it chooses to use to mediate information is very important.
The following is multiple choice question (with options) to answer.
What is controlled by both genes and experiences in a given envionment? | [
"instincts",
"learned behaviors",
"reflexes",
"animal behaviors"
] | D | Most animal behaviors are controlled by both genes and experiences in a given environment. |
SciQ | SciQ-13 | human-biology, nutrition
Title: Do we know a complete list of nutrients that humans must ingest to live? When the people who are making "nutritionally complete" foods like Soylent are developing their product, how do they know that they've covered all their bases? You need to have protein, carbohydrates, fats etc., but what about vitamins or minerals?
Has science produced a commonly accepted list of all the nutrients that humans need to live? For babies there is certainly a formula available for a complete menu for survival: formula*
Here are the nutrition facts from Nestlé's "Good Start":
Formula nutrition facts. source: Nestlé
Comparable lists are available for people that cannot eat normally (e.g. people in a comatose state) and are fed enteral or parenteral nutrition.
*. Remember though, breast is best :)
The following is multiple choice question (with options) to answer.
What tells you how much of the food you should eat to get the nutrients listed on the label? | [
"serving size",
"regular size",
"scoop size",
"longer size"
] | A | The information listed at the right of the label tells you what to look for. At the top of the label, look for the serving size. The serving size tells you how much of the food you should eat to get the nutrients listed on the label. A cup of food from the label pictured below is a serving. The calories in one serving are listed next. In this food, there are 250 calories per serving. |
SciQ | SciQ-14 | standard-model, radioactivity
Title: Predicting Decay Rates via the Standard Model Question 7584 illustrated a procedure to forecast the decay rates of isotopes with known long average lifetimes. Lifetimes of the many U isotopes vary from micoseconds to gigayears. F has only one stable isotope while Sn has 10. Can Standard Model principles be used to predict the stability of isotopes and the average lifetimes for unstable isotopes, or can this only be done by measurement? The nuclear forces are a complex amalgam of primarily Quantum Chromodynamics forces and electromagnetic ones, but to deal with the diagramatic way of calculating in Quantum Field Theory, is not possible. The weak force responsible for beta decays should also be in the calculations.Too many diagrams and too convoluted.
Quantum mechanical models with a potential well to estimate the collective forces are used for this. Nuclear physics has been using various models successfully, like the shell model. to predict energy levels in nuclei.
Ways of estimating lifetimes are taught in nuclear engineering, for example:
Course Outcomes: Students must be
able to...
calculate the consequences of radioactive
growth and decay and nuclear reactions.
calculate estimates of nuclear masses and energetics
based on empirical data and nuclear models.
calculate estimates of the lifetimes of nuclear
states that are unstable to alpha-,beta- and gamma decay and internal
conversion based on the theory of simple nuclear models.
use nuclear models to predict low-energy level
structure and level energies.
The following is multiple choice question (with options) to answer.
What are used to write nuclear equations for radioactive decay? | [
"radioactive symbols",
"nuclear symbols",
"trigonometric symbols",
"critical symbols"
] | B | Nuclear symbols are used to write nuclear equations for radioactive decay. Let’s consider the example of the beta-minus decay of thorium-234 to protactinium-234. This reaction is represented by the equation:. |
SciQ | SciQ-15 | genetics, homework
Title: "structural and regulatory elements of genes" Can anyone please explain a little about these two elements of genes? My main problem is with "which ‘switch on’ instructions".
genes have structural elements (which code for a particular protein) and regulatory elements (which ‘switch on’ instructions) The expression of protein coding genes happens by the process of transcription. So promoters facilitate access of the RNA polymerase complex to DNA to begin transcribing a locus on the genome. The promoter of a gene often contains sequences that bind proteins called transcription factors, which play a role in various parts of the transcriptional process as well as components of RNA polymerase themselves (Such as a Pribnow box in prokaryotes, or a TATA box or an initiator element in animals).
So whether a gene is turned on and if so, how much it is turned on, is a property of how many transcription factor binding sites exist in the promoter, the nature of the transcription factors themselves in terms of their influence on transcription, and in eukaryotes and some archaea, epigenetic processes that control the access of transcriptional machinery to the locus being transcribed.
So when you think about the two elements in a gene, think of a light (the bit of a gene that codes for proteins) and a dimmer (which controls how much RNA is made by the protein-coding bit)
The following is multiple choice question (with options) to answer.
What is controlled by regulatory proteins that bind to regulatory elements on dna? | [
"gene transcription",
"substance transcription",
"amino acids",
"mRNA"
] | A | Gene transcription is controlled by regulatory proteins that bind to regulatory elements on DNA. The proteins usually either activate or repress transcription. |
SciQ | SciQ-16 | bond, erratum
Title: Why does boron trifluoride form boron tetrafluoride ion instead of boron pentafluoride ion? From ChemWiki by UC Davis:
As a side note, it is important to note that $\ce{BF3}$ frequently bonds with a $\ce{F-}$ ion in order to form $\ce{BF4-}$ rather than staying as $\ce{BF3}$. This structure completes boron's octet and it is more common in nature.
Wait, what? Boron has three electrons. Bonding with four fluoride ions gives it four electrons — these are covalent bonds (shared electrons). That makes for a grand total of 7 valence electrons. Did the author mean $\ce{BF_5^2-}$? As you point out, the $\ce{B}$ in $\ce{BF_3}$ is sharing a total of 6 electrons, 3 from the boron and 3 from the three fluorines. Now add a fluoride anion that brings 2 more electrons to share. This now makes for a total of 8 electrons around the boron.
The following is multiple choice question (with options) to answer.
Boron only occurs naturally in compounds with what element? | [
"oxygen",
"helium",
"carbon",
"nitrogen"
] | A | Occurrence, Preparation, and Compounds of Boron and Silicon Boron constitutes less than 0.001% by weight of the earth’s crust. In nature, it only occurs in compounds with oxygen. Boron is widely distributed in volcanic regions as boric acid, B(OH)3, and in dry lake regions, including the desert areas of California, as borates and salts of boron oxyacids, such as borax, Na2B4O7⋅10H2O. Elemental boron is chemically inert at room temperature, reacting with only fluorine and oxygen to form boron trifluoride, BF3, and boric oxide, B2O3, respectively. At higher temperatures, boron reacts with all nonmetals, except tellurium and the noble gases, and with nearly all metals; it oxidizes to B2O3 when heated with concentrated nitric or sulfuric acid. Boron does not react with nonoxidizing acids. Many boron compounds react readily with water to give boric acid, B(OH)3 (sometimes written as H3BO3). Reduction of boric oxide with magnesium powder forms boron (95–98.5% pure) as a brown, amorphous powder: B 2 O 3(s) + 3Mg(s) ⟶ 2B(s) + 3MgO(s) An amorphous substance is a material that appears to be a solid, but does not have a long-range order like a true solid. Treatment with hydrochloric acid removes the magnesium oxide. Further purification of the boron begins with conversion of the impure boron into boron trichloride. The next step is to heat a mixture of boron trichloride and hydrogen: 1500 °C. |
SciQ | SciQ-17 | cell-biology, nutrition, blood-circulation, liver
Title: How do nutrients get to the cells they need to get to? I understand the basics of digestion. I know that nutrients get absorbed by the microvilli, enter the bloodstream and travel to the liver but after all that, what is the biological mechanism that guides these nutrients to the proper receiving location? Broadly speaking, nutrients that enter the blood from the gut, and those that are released into the blood by the liver, are available to any cells that require them. So there is no "guiding to the correct location" in the sense that you suggest.
Lipids for example are present in the various lipoproteins and can be acquired from these by all cells. Iron is bound to transferrin, and any cell with transferrin receptors can internalise the transferrin and take the iron. Glucose is available in solution in the plasma, and free fatty acids are bound to serum albumin in the blood. During starvation the liver produces ketones ("ketone bodies") which are taken up by many different tissues/cell types.
The following is multiple choice question (with options) to answer.
What organ systems link exchange surfaces with cells throughout the body? | [
"nervous",
"pulmonary",
"circulatory",
"vascular"
] | C | 42.1 Circulatory systems link exchange surfaces with cells throughout the body. |
SciQ | SciQ-18 | human-biology, digestive-system, immune-system, microbiome
All of these immune cells also respond to diffused chemical signals called cytokines. These molecules are secreted by some cells and are received by receptors on the host cells. Sometimes the secretion is by another immune cell, sometimes it is from a non-immune system host cell, and sometimes these molecules can be secreted by the bacteria, fungi, or worms themselves.
Depending on the chemical signals that are secreted, and how the cells are interacting at the time of the message, and which cells are receiving the message, will determine the response to the message. It is contextual. Think of the phrase "You're killing me." If someone says it, while laughing, to a good friend who is telling jokes, it means one thing. If it is screamed as someone is being choked by an attacker, it means something very different.
To summarize, the immune cells are surveilling the environment and trying to pick up what is friend and what is foe and they try to respond accordingly.
Over time and coevolution, our microbiomes have developed ways of communicating with our immune system to let it know that these microbes do not mean any harm. They are able to "train" the immune cells using chemical signaling to temper the immune systems response to them (15), and this is how they are able to coexist within our body and with an immune system that is constantly on seek an destroy missions. Also because of the mucus, our microbiome usually isn't in direct contact with our cells, so it is a different kind of interaction than if an infecting pathogen were to breech the barriers and gain access to sterile areas where no bacteria or fungi should be found, and as a result, the immune system reacts differently.
The following is multiple choice question (with options) to answer.
What occurs when the immune system attacks a harmless substance that enters the body from the outside? | [
"plague",
"allergy",
"panic attack",
"nausea"
] | B | An allergy occurs when the immune system attacks a harmless substance that enters the body from the outside. A substance that causes an allergy is called an allergen. It is the immune system, not the allergen, that causes the symptoms of an allergy. |
SciQ | SciQ-19 | genetics, cell-biology, embryology, meiosis, gamete
Title: Fertilization of the human egg- where does our centrosome come from? Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can have a centrosome? If this is so, then how did oogenesis happen? ? To answer the first part of your question. The sperm actually introduces two centrosomes. The centrosome then nucleates the new microtubule assembly to form the sperm aster — a step essential for successful fertilization. You can visit these sites Simerly, et al as well as Paweltz, et al
The following is multiple choice question (with options) to answer.
Fertilization is the union of a sperm and egg, resulting in the formation of what? | [
"a zygote",
"a bacteriophage",
"a cytoplasm",
"a nuclei"
] | A | Fertilization is the union of a sperm and egg, resulting in the formation of a zygote. |
SciQ | SciQ-20 | evolution, embryology, chromosome, polyploidy
Polyploidy is an important evolutionary mechanism which was and is probably responsible for a great deal of biological diversity.
Polyploidy arises easily in both animals and plants, but reproductive strategies might prevent it from propagating in certain circumstances, rather than any reduction in fitness resulting from the genome duplication.
Polyploidy may be more prevalent in animals than previously expected, and the imbalance in data arises from the fact that cytogenetics (i.e. chromosome counting) of large populations of wild specimens is a very common practise in botany, and very uncommon in zoology.
In addition, there are now several new suspected factors involved in ploidy which are currently being investigated:
The following is multiple choice question (with options) to answer.
The plants alternation between haploid and diploud generations allow it to do what? | [
"reproduce asexually and simultaneously",
"reproduce asexually and biologically",
"reproduce asexually and sexually",
"reproduce sexually and autonomously"
] | C | All plants have a characteristic life cycle that includes alternation of generations . Plants alternate between haploid and diploid generations. Alternation of generations allows for both asexual and sexual reproduction. Asexual reproduction with spores produces haploid individuals called gametophytes . Sexual reproduction with gametes and fertilization produces diploid individuals called sporophytes . A typical plant’s life cycle is diagrammed in Figure below . |
SciQ | SciQ-21 | metabolism, human-anatomy, pharmacology, liver
For drugs introduced through an injection, for example, metabolism occurs throughout the circulatory system and in the liver. Remember that it's all the same blood supply, but the first-pass effect just refers to the blood that goes to the liver before entering the systemic circulation (by which it can travel to its target).
The following is multiple choice question (with options) to answer.
Most of the chemical reactions in the body are facilitated by what? | [
"carbohydrates",
"proteins",
"vitamins",
"enzymes"
] | D | Enzymes are critical to the body’s healthy functioning. They assist, for example, with the breakdown of food and its conversion to energy. In fact, most of the chemical reactions in the body are facilitated by enzymes. |
SciQ | SciQ-22 | pregnancy, children
Title: What happens to the umblical cord inside the mother? After giving birth to a child, the umblical cord is cut (and stored if they want). The end connected to the child's navel will fell off eventually but what happens to the end inside the mother?
Will it be removed right after birth by doctors or what happens? Labor is typically divided into 3 stages:
Stage 1: From the onset of contractions (true labor pains) to full dilatation of the cervix (which is about 10 cm) - this takes about 12 to 18 hours
Stage 2: From full dilatation of cervix to expulsion of fetus - This takes about ~ 30 minutes
Stage 3. From expulsion of fetus to expulsion of placenta - this takes about ~ 15 minutes. During the third stage, the umblical cord which is attached to placenta is expelled along with the placenta. This would be the answer to your question.
Source:Hympath.com
The following is multiple choice question (with options) to answer.
What is the termination of a pregnancy in progress called? | [
"miscarriage",
"abortion",
"contraception",
"delivery"
] | B | |
SciQ | SciQ-23 | everyday-chemistry, extraction, green-chemistry
Title: Phosphate extraction from sewage I read that phosphate reserves will exhaust in coming years wiki, why don't we extract it from sewage , is it really that difficult to extract phosphate ? The idea has been proposed by several journal articles and Wikipedia suggests that it is being done already. In "Phosphate fertilizer from sewage sludge ash (SSA)", Franz proposes a method
whereby more than 90% of phosphorus can be extracted to make an adequate phosphate fertilizer
Also, the journal "Phosphorus recycling in sewage treatment plants with
biological phosphorus removal" by Heinzman lists three processes:
Krepo Process
Seaborne Process
Aqua Reci Process
In it Heinzman also mentions that
up to now no phosphorus recycling with a defrayal of costs is possible. The future importance of phosphorus recycling will depend on the market price for raw phosphate, the recycling costs and, furthermore, on the general political framework
So, it appears that it is cheaper to mine it than to recycle it. This may change in the future of course.
The following is multiple choice question (with options) to answer.
Cutting down on the use of chemical fertilizers and preserving wetlands are ways to prevent what "unlivable" regions in bodies of water? | [
"dead zones",
"inhabitable zones",
"fresh zones",
"hostile zones"
] | A | Cutting down on the use of chemical fertilizers is one way to prevent dead zones in bodies of water. Preserving wetlands is also important. Wetlands are habitats such as swamps, marshes, and bogs where the ground is soggy or covered with water much of the year. Wetlands slow down and filter runoff before it reaches bodies of water. Wetlands also provide breeding grounds for many different species of organisms. |
SciQ | SciQ-24 | human-anatomy
[source]
And now, follow along with your own hand!
finger (4 DOF): each finger has 2 interphalangeal joints between the distal, middle and proximal phalanges that allow for flexion/extension (2 DOF); each finger also has a metacarpophalangeal joint between the proximal phalanx and the metacarpal that allows for flexion/extension as well as abduction/adduction (2 DOF)
thumb (5 DOF): an interphalangeal joint between the distal and proximal phalanges allowing flexion/extension (1 DOF); a metacarpophalangeal joint between the proximal phalanx and metacarpal allowing flexion/extension and abduction/adduction (2 DOF); a carpometacarpal joint between the metacarpal and trapezium allowing flexion/extension and abduction/adduction (2 DOF)
wrist (6 DOF): between the carpals and radius allowing flexion/extension, abduction/adduction and supination/pronation (3 DOF); I think when the authors refer to translation of the wrist, they are simply saying that hand can be moved in all planes of 3D space (ie up/down, side to side, forward/backward - 3 DOF)
Since we have 4 fingers, they give 16 DOF. Adding the 5 DOF of the thumb and 6 of the wrist, we get 27. Please nobody question my reasoning. Thank you.
The following is multiple choice question (with options) to answer.
Which muscles allow your fingers to also make precise movements for actions? | [
"paired muscles",
"intrinsic muscles",
"motoric muscles",
"fine movement muscles"
] | B | Intrinsic Muscles of the Hand The intrinsic muscles of the hand both originate and insert within it (Figure 11.28). These muscles allow your fingers to also make precise movements for actions, such as typing or writing. These muscles are divided into three groups. The thenar muscles are on the radial aspect of the palm. The hypothenar muscles are on the medial aspect of the palm, and the intermediate muscles are midpalmar. The thenar muscles include the abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, and the adductor pollicis. These muscles form the thenar eminence, the rounded contour of the base of the thumb, and all act on the thumb. The movements of the thumb play an integral role in most precise movements of the hand. The hypothenar muscles include the abductor digiti minimi, flexor digiti minimi brevis, and the opponens digiti minimi. These muscles form the hypothenar eminence, the rounded contour of the little finger, and as such, they all act on the little finger. Finally, the intermediate muscles act on all the fingers and include the lumbrical, the palmar interossei, and the dorsal interossei. |
SciQ | SciQ-25 | quantum-mechanics, quantum-field-theory, commutator, observables, decoherence
My question refers to "measured observables". Of course, the concept of "measurement" is inherently ambiguous: there is no clear line between "has been measured" and "has not been measured". However, we are still able to use quantum theory very effectively because we can empirically recognize whether or not an observable has been measured, despite the technical ambiguity in exactly where the line should be drawn. Since laboratories are made of molecules (etc), I infer that we should also be able to recognize what has been measured on paper, using a model that includes all those molecules (etc) and that respects the principles of quantum field theory. The ambiguity inherent in the definition of "measurement" should not be any more of an obstacle on paper than it is in the usual empirical approach. The required calculations may be prohibitively difficult in practice, but the question is still meaningful in principle, and I wonder if it might be answerable by some kind of general theorem even if the details in specific examples are intractible.
My question says "well-measured" instead of just "measured". This is meant to exclude "weak measurements" in which the state of the thing being measured does not strongly influence the state of the rest of the system (the laboratory). An example of a "weak measurement" would be trying to use radio waves with a wavelength of 100 km to monitor the location of an electron in a typical laboratory-scale double-slit experiment. In that case, we would not say that the electron's location has been "well-measured" by the influence it exerts on the radio waves. But if the radio waves are replaced by gamma-rays, then the electron's location can be "well-measured." The key here is that my question refers only to situations in which the thing being measured strongly influences the rest of the system, in a way that clearly distinguishes between the possible outcomes.
The following is multiple choice question (with options) to answer.
Testing what usually requires making observations or performing experiments? | [
"homeostasis",
"hypothesis",
"conclusion",
"variables"
] | B | Usually, testing a hypothesis requires making observations or performing experiments. In this case, we will look into existing scientific literature to see if either of these hypotheses can be disproved, or if one or both can be supported by the data. |
SciQ | SciQ-26 | atomic-physics
Title: What gives covalent bond its strength? I came across the following passage from Structure and Properties chapter of Morrison-Boyd Organic Chemistry:
What gives the covalent bond its strength? It is the increase in electrostatic attraction. In the isolated atoms, each electron is attracted by-and attracts-one positive nucleus;in the molecule, each electron is attracted by two positive nuclei.
However, I don't think it refers to the force holding each atom together. It rather, merely describes the increase in the electrostatic force of attraction between the electrons and the nuclei. I believe that bond strength is a measure of the difficulty in pulling apart the component atoms, not the electrons from the positive nuclei.
What exactly is the pattern or picture of the forces on the nuclei and the electrons, due to one another, that holds the component atoms together? (I am aware that the decrease in overall energy or increase in stability is definitely not a reason to account for the strength of covalent bond, but rather a consequence of the action of such forces.) It probably helps to define what a covalent bond really is. Covalent bonds occur when one or more Atomic Orbitals (AO) of the participating atoms constructively interact and form a (bonding) Molecular Orbital (MO). The figure below schematises the formation of a $\sigma_{ss}$ MO when two hydrogen atoms combine to form a dihydrogen molecule:
The following is multiple choice question (with options) to answer.
This sharing of electrons produces what is known as a covalent bond. covalent bonds are ~20 to 50 times stronger than what? | [
"van der waals interactions",
"Newton's third law",
"Mendelian systems",
"gravitational pull"
] | A | any other electron, they become a part of the molecule’s electron system.204 This sharing of electrons produces what is known as a covalent bond. Covalent bonds are ~20 to 50 times stronger than van der Waals interactions. What exactly does that mean? Basically, it takes 20 to 50 times more energy to break a covalent bond compared to a van der Waals interaction. While the bonded form of atoms in a molecule is always more stable than the unbounded form, it may not be stable enough to withstand the energy delivered through collisions with neighboring molecules. Different bonds between different atoms in different molecular contexts differ in terms of bond stability; the bond energy refers the energy needed to break a particular bond. A molecule is stable if the bond energies associated with bonded atoms within the molecule are high enough to survive the energy delivered to the molecule through either collisions with neighboring molecules or the absorption of energy (light). When atoms form a covalent bond, their individual van der Waals surfaces merge to produce a new molecular van der Waals surface. There are a number of ways to draw molecules, but the spacefilling or van der Waals surface view is the most realistic (at least for our purposes). While realistic it can also be confusing, since it obscures the underlying molecular structure, that is, how the atoms in the molecule are linked together. This can be seen in this set of representations of the simple molecule 2methylpropane (→).205 As molecules become larger, as is the case with many biologically important molecules, it can become impossible to appreciate their underlying organization based on a van der Waals surface representation. Because they form a new stable entity, it is not surprising (perhaps) that the properties of a molecule are quite distinct from, although certainly influenced by, the properties of the atoms from which they are composed. To a first order approximation, a molecule’s properties are based on its shape, which is dictated by how the various atoms withjn the molecule are connected to one another. These geometries are imposed by each atom’s underlying quantum mechanical properties and (particularly as molecules get larger, as they so often do in biological systems) the interactions between different parts of the molecule with one another. Some atoms, common to biological systems, such as hydrogen (H), can form only a single covalent bond. Others can make two (oxygen (O) and sulfur (S)), three (nitrogen (N)), four (carbon (C)), or five (phosphorus (P)) bonds. In addition to smaller molecules, biological systems contain a number of distinct types of extremely large molecules, composed of many thousands of atoms; these are known as macromolecules. Such macromolecules are not rigid; they can often fold back on themselves leading to intramolecular interactions. There are also interactions between molecules. The strength and specificity of these interactions can vary dramatically and even small changes in molecular structure (such as caused by mutations and allelic variations) can have dramatic effects. |
SciQ | SciQ-27 | physical-chemistry
Title: Where and how do particles move? I've been thinking of making a simple 2d game of some sort involving particles and I've stumbled upon something I haven't really thought about. I know a lot about chemistry, so I'm not new to particles and their behavior, but I realized that I don't know how particles move. What causes them to move, and in what direction to they move. Take water molecules. When water is a liquid, it sticks together due to the polarity of water molecules, but due to the energy and motion of the molecules, it doesn't quite remain as a solid. In the gas state, the energy is even higher allowing the molecules to separate even farther from each other
The final question from all of this is if I were to simulate molecules/particles in a solid, liquid, and gas state, how would I make them move? The inter-molecular attractions are easy enough to code but the motion is what I don't understand. Do they just move randomly all the time, or is there a particular reason why a certain particle would move in a certain direction? Assuming the simplest of cases where the interaction is only during the collision, you can initiate your particles with random velocities sampled from Maxwell-Boltzmann distribution and random positions.
Then evolve them simply with their respective velocities until they collide, where you can use conservation of energy and momentum to decide new velocities. This is basically kinetic theory of gases.
The following is multiple choice question (with options) to answer.
Water molecules move about continuously due to what type of energy? | [
"potential",
"kinetic",
"seismic",
"optical"
] | B | Water molecules move about continuously due to their kinetic energy. When a crystal of sodium chloride is placed into water, the water’s molecules collide with the crystal lattice. Recall that the crystal lattice is composed of alternating positive and negative ions. Water is attracted to the sodium chloride crystal because water is polar and has both a positive and a negative end. The positively charged sodium ions in the crystal attract the oxygen end of the water molecules because they are partially negative. The negatively charged chloride ions in the crystal attract the hydrogen end of the water molecules because they are partially positive. The action of the polar water molecules takes the crystal lattice apart (see image below). |
SciQ | SciQ-28 | 8 Replies
Sort By:
Posted 5 years ago
Nice! Thanks for sharing. I was already wondering if you had used BlockMap or Map[...Partition[...]], but well, you thought of both.
Posted 5 years ago
Actually, I used a compiled version of Map + Partition when @Yode in the StackExchange chatroom reminded me of BlockMap. Strangely, their timing scales differently with problem size, but I haven't investigated in detail yet.
Posted 5 years ago
Felicitation, very pedagogic André Dauphiné
Posted 5 years ago
- Congratulations! This post is now Staff Pick! Thank you for your wonderful contributions. Please, keep them coming!
Posted 5 years ago
This is so cool.
Posted 5 years ago
Thanks for sharing this sweet post, Szabolcs. It looks like you manage to snap a picture where the parallax is not messing up too much the computation.Does it make sense to compare structures with similar fractal dimensions? What objects would we find with a dimensions around 1.85 like these trees?
The following is multiple choice question (with options) to answer.
A small scale version of what type of map displays individual rock units? | [
"geologic map",
"polar map",
"seismic map",
"geographic map"
] | A | Geologic maps display rock units and geologic features. A small scale map displays individual rock units while a large scale map shows geologic provinces. |
SciQ | SciQ-29 | evolution
Title: How to define "evolution"? The standard answer found in intro course to evolutionary biology to the question:
what is evolution?
is:
It is a change in allele frequency over time!
I believe a complete definition should encompass the following concepts:
mutations
copy number variation (CNV)
codon usage
chromosome numbers
phenotypic change (whether heritable or not)
Complex phenotypic trait such as plasticity and developmental noise
maybe some other things...
My questions are:
Would it be worth it to talk about phenotype in a definition of evolution?
What are the alternative definitions that have been proposed?
What is your definition?
Note: I would rather talk about genetic evolution, but if you think it is worth making one definition for genetic and cultural (and some other stuff maybe) evolution, you're free to suggest it! What is evolution?
In a non-biological sense, evolution means change:
"a process of [...] change"
Biological evolution (seeing as this is Biology stack exchange) then needs to be tweaked to give a biologically specific context. Many textbooks etc. give definitions of evolution and here are a few good ones from across the history of evolutionary biology:
Charles Darwin:
"Descent with modification".
Mark Ridley1:
"Evolution means change, change in the form and behaviour of organisms between generations. ... When members of a population breed and produce the next generation we can imagine a lineage of populations, made up of a series of populations through time. Each population is ancestral to the descendant population in the next generation: a lineage is an ancestor-descendent series of populations. Evolution is then change between generations within a population lineage."
Brian and Deborah Charlesworth2:
"Evolution means cumulative change over time in the characteristics of a population of living organisms. ... All evolutionary changes require initially rare genetic variants to spread among the members of a population, rising to high frequency..."
All of these have a common theme. Biological information is moving through time, descending with a degree of directionality (e.g. parent $\rightarrow$ offspring), and the information is modified with time.
Personally I would define evolution as:
The following is multiple choice question (with options) to answer.
What is defined as a change in the inherited traits of organisms over time? | [
"evolution",
"generation",
"variation",
"divergence"
] | A | One idea is that evolution happens. Evolution is a change in the inherited traits of organisms over time. Living things have changed as descendants diverged from common ancestors in the past. |
SciQ | SciQ-30 | physiology
So, now the question is shifted: why do kisspeptin neurons show up only at puberty? We don't know for sure, but it looks like increased levels of E2 could be important for this.
Again, we get into a self-sustaining cycle. Growth of the body generates an increase in E2 production (possibly due to increased volume of the gonads?), which, when over a certain level permits the development of kisspeptin neurons, which will then stimulate the GnRH neurons, resulting in increased LH and E2. We then have more E2 and this makes kisspeptin neuron grow even more etc etc.
The following is multiple choice question (with options) to answer.
What hormone, which is associated with luteinizing hormone and male sexuality, helps bring about physical changes in puberty? | [
"epinephrine",
"steroids",
"testosterone",
"estrogen"
] | C | What causes puberty to begin? The hypothalamus in the brain “tells” the pituitary gland to secrete hormones that target the testes. The main pituitary hormone involved is luteinizing hormone (LH) . It stimulates the testes to secrete testosterone. Testosterone, in turn, promotes protein synthesis and growth. It brings about most of the physical changes of puberty, some of which are shown in Figure below . In addition to the changes shown below, during puberty male facial hair begins to grow, the shoulders broaden, and the male voice deepens. You can watch an animation of these and other changes that occur in boys during puberty at the Interactive Body link: http://www. bbc. co. uk/science/humanbody/body/interactives/lifecycle/teenagers/ . |
SciQ | SciQ-31 | botany, reproduction
Title: Are the seeds in a single capsicum fruit genetically identical? Hopefully not a too-basic question for the venue. I'm a chile pepper growing hobbyist and have spent some time searching around and reading up on pepper (angiosperm) reproduction, but I'm not getting a clear picture of the details.
It seems like flowers have multiple ovules and it seems like one pollen-grain landing on the stigma leads to fertilization of a single ovule. And it seems like that process produces a single seed.
But that fertilization also prompts fruit growth and flower death and capsicum fruits have many seeds, never just one (that I've ever seen).
So, does each seed have a potentially different father? Or are the multiple seeds generated through a reproductive/cloning process that I'm not seeing written about? Or something else? No, the seeds are not genetically identical. Each seed come from the fertilization of an ovum with a sperm from a separate pollen grain. Since each pollen grain can come from a different plant, the seeds will generally differ from one another.
Additionally, even ova from a single plant will not usually be genetically identical to one another. This is because the process that creates the ova (meiosis) shuffles the genes of the parent plant on then places only half into the ovum. The same kind of shuffling goes on in the creation of pollen grains.
In the chili pepper genus (Capsicum), plants are predominantly self-pollinating. This means the majority of the pollen for the seeds in a fruit will come from the very same plant. This generally reduces the amount of variation seen in the offspring compared to complete cross-plant pollination. Some cross-pollination can nevertheless occur if there are other varieties in the neighborhood. The fruit will not show the effects of the new genetic combinations present in its seed, but only a plant grown from the seed will make the differences evident.
The following is multiple choice question (with options) to answer.
Where do angiosperms produce seeds in flowers? | [
"testes",
"ovaries",
"cones",
"germs"
] | B | Seed plants called angiosperms produce seeds in the ovaries of flowers. |
SciQ | SciQ-32 | metabolism, ecology, photosynthesis
Title: Why isn't phosphorus or nitrogen a limiting nutrient for animals? Nitrogen and Phosphorus are usually the limiting nutrient for plants, especially for algae. Phosphorus is used for DNA, ATP and phospholipids, and Nitrogen is used for pretty much every protein a cell might want to produce. That is, their need for biological processes is not tied specifically to photosynthesis: anything that lives is going to need them, pretty much for anything it might want to do. It would make sense for them to be a limiting nutrient for almost anything that's trying to grow, plant or animal.
Yet for animals the limiting "nutrient" seems to always be energy, ie: food. Why aren't animals limited by lack of nutrients in the same way that plants are? Obviously animals need these nutrients, too. Or to reverse the question, why do plants need so much more phosphorus/nitrogen than animals do?
My best guess is that an animal's digestion of plant material is relatively inefficient energy-wise but relatively efficient nutrient-wise. So for an animal to eat enough food to have sufficient energy to survive, it's probably eaten more than enough Nitrogen and Phosphorus for its needs. But I'm just guessing and I can't find any data that would back up that guess. Phosphorus
Your suggestion that if we are meeting our calorific requirement we will be getting enough is true for phosphorus.
Most foods contain lots of phosphorus. The maximum dietary requirement occurs during adolescent growth, estimated at 1250 mg per day. Assuming a calorie intake of 2500 kcal we can calculate a 2500 kcal equivalent phosphorus content for various foods:
skimmed milk contains 7,400 mg phosphorus per 2500 kcal
roasted chicken breast contains 7,500 mg phosphorus per 2500 kcal
cooked white rice contains 3840 mg per 2500 kcal
(Calculations are based upon values obtained via this site.)
Nitrogen
Our requirement for nitrogen is met by our protein intake: inadequate protein intake manifests as kwashiorkor which is essentially due to a dietary deficiency of essential amino acids. In other words, the only way to achieve a nitrogen-deficient diet is to not eat protein, and this would not be alleviated by any inorganic source of nitrogen, even if we could consume enough of such a N source.
The following is multiple choice question (with options) to answer.
In order to create food, what do photosynthetic protists use? | [
"hydrocarbons",
"decayed matter",
"thermal energy",
"light energy"
] | D | Photosynthetic protists use light energy to make food. They are major producers in aquatic ecosystems. |
SciQ | SciQ-33 | ornithology, reptile, cladistics
Title: If dinosaurs could have feathers, would they still be reptiles? I just finished watching a video where it was mentioned that nowadays birds are dinosaurs and non-avians dinosaurs could have feathers.
I confirmed this from wikipedia:
Birds are highly advanced theropod dinosaurs, characterised
by feathers, a beak with no teeth, the laying of hard-shelled eggs, a
high metabolic rate, a four-chambered heart, and a lightweight but
strong skeleton.
And:
Direct fossil evidence of feathers or feather-like structures has
been discovered in a diverse array of species in many non-avian
dinosaur groups, both among saurischians and ornithischians.
And this family tree of reptiles mentions:
Archosauriformes (crocodiles, birds, dinosaurs and extinct relatives)
And later in the Mesozoic era:
The dinosaurs also developed smaller forms, including the feather-bearing smaller theropods.
The following is multiple choice question (with options) to answer.
What type of vertebrates are birds? | [
"endothermic tetrapod",
"invertebrates",
"epidermal tetrapod",
"exothermic"
] | A | Birds are endothermic tetrapod vertebrates. They are bipedal, which means they walk on two legs. Birds also lay amniotic eggs, and the eggs have hard, calcium carbonate shells. Although birds are the most recent class of vertebrates to evolve, they are now the most numerous vertebrates on Earth. Why have birds been so successful? What traits allowed them to increase and diversify so rapidly?. |
SciQ | SciQ-34 | ions
Title: What does it mean when something is said to "contain ions"? (I'm looking for a very basic level explanation because my only chemistry experience is one fast-paced high school course.)
So, according to the professor of that course, ions are never found in nature as ions; everything would be neutrally charged. My question is, how can something have ions in it, without having them be neutralized? Doesn't nature want to lower potential energy, which would mean bonding the ions asap? Or am I misunderstanding things and said ions are already bonded to other ions, but they are still called ions even though the charge of the whole molecule should be neutral? Your teacher is almost right but some terminology needs to be clarified.
Pure substances will almost always be electrically neutral (and the exceptions involve temporary local transfer of electrons from one substance to another as when you rub a rubber balloon on a wall surface). Beyond a certain level of charge separation you get enough electrical potential to cause sparks which allows the charges to equalise again. So persistent charge imbalance isn't easy to get. I think that is what your teacher means.
But if you look inside some pure substances, they do contain ions, just an equal number of each to avoid the bulk material having an overall charge. Common salt, for example, consists of ions (Na+ and Cl- in equal numbers). The substance is neutral, but the individual atoms making it up are all ions.
So your teacher is wrong if she meant that ions don't exist in nature but correct if she meant that bulk substances are electrically neutral.
The following is multiple choice question (with options) to answer.
What type of ions do ionic compounds contain? | [
"negative and neutal",
"positive and negative",
"positive and charged",
"regular and irregular"
] | B | An ionic compound contains positive and negative ions. |
SciQ | SciQ-35 | evolution, biochemistry, plant-physiology, plant-anatomy, life
Title: Plants without bacteria? is it theoretically possible? I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But it is a natural way.
But is it possible to have a world with plants (without mammals or microorganisms and without bacteria) that could exist in the long term. Saying the atmosphere of these world has already enough nitrogen, oxygen and CO2, and of course there is water.
What could break this artificially created world with such conditions (say the world created not from low-level living structures)?
Could bacteria emerge in the world? This is the sort of question that should be considered from more than one perspective. Since this is speculation, take it as a given that there is a lot of 'what if' here.
I doubt most animals and plants can do entirely without bacteria - as you say most of the essential nutrients come from bacteria, who fix nitrogen. If only plants were left on earth, eventually the plants would use up all the nitrogen and they would have to find a way to fix more.
Can bacteria emerge from just a world of plants? I don't think viruses arise spontaneously, but since genomes often have viruses embedded in them, over the course of a billion years or so, its possible since bacteria and viruses continue to be impressed upon our genomes. Would it happen in time? Most would be skeptical whether that timing could work out.
In practice it would be hard to create a world like this. I would be interested to see whether you could sterilize the microorganisms off of seeds without killing the plant for instance. If you're asking about a small sterile environment with only plants, you could do it by adding the nutrients the plants need and giving them sunlight. Such self sustaining systems have been made with cyanobacteria and i'd be surprised if plants could not be included. But these are closed systems and judged by limited amounts of time, so whether this is an answer to your question is not clear. Here it looks like some water plants and fish have been done. If there was a plant that created CO₂ at an adequate rate its possible.
The following is multiple choice question (with options) to answer.
All living things need air and this to survive? | [
"ecosystem",
"water",
"habitat",
"stimuli"
] | B | |
SciQ | SciQ-36 | cell-biology, microbiology
Title: Are there any organisms that are made of more than one (~5-12) cell? Prokaryotes and eukaryotes are unicellular, made of one cell. Great. Eukaryotes are unicellular or multicellular. But the typical examples of multicellular eukaryotes we have are made of, often, trillions of cells, like us humans. Ants must still be made of many millions of cells. Are there known eukaryotes with very few cells that make them up? Like, 5, or something? Or maybe a dozen cells making up the whole organism in its fully developed state? There's Trichoplax adhaerens, a Placozoa, made of a few thousand cells. Then there is Dicyema japonicum, a simple mesozoan, made up of 9 to 41 cells. Arguably, the simplest multicellular organism is the algae Tetrabaena socialis, whose body consists of 4 cells. Then, there's the parasitic Myxozoa which have 7 cells.
The following is multiple choice question (with options) to answer.
The cells of all eukarya have a what? | [
"necrosis",
"chloroplast",
"epidermis",
"nucleus"
] | D | Some Eukarya are also single-celled, but many are multicellular. Some have a cell wall; others do not. However, the cells of all Eukarya have a nucleus and other organelles. |
SciQ | SciQ-37 | hydrology, rivers, geomorphology
Mountain ranges are often formed from orogeny, where tectonic plates collide. Rivers starts at high altitude, radiating out in all directions from mountains, but as collisions in the present continental settings are often on the rim of large plates (e.g Andes, Alps, Himalaya), and the rivers can't cross the range, it will have to travel the whole continental plate to reach ocean level. In the case of Asia, most large rivers starts in Himalaya (or other tectonic active regions, as Altai), in Europe large rivers starts in the Alps. In Africa, they start in the tectonic active rift zone.
This map shows the ocean drainage dividers. The border between the drainage areas are the line where rivers start.
The following is multiple choice question (with options) to answer.
What type of plate boundaries produce huge mountain ranges in the ocean basin? | [
"parallel",
"coherent",
"divergent",
"tractional"
] | C | Divergent plate boundaries produce huge mountain ranges under water in every ocean basin. |
SciQ | SciQ-38 | transition-metals, oxidation-state
The "free electrons" in the reference apparently refer to the possibility that stoichiometric Group V carbides may contain metal(V) and free electrons (e.g. $\ce{Nb^{V}C^{-IV}e^-}$) or a Group 4 carbide might be carbon deficient and thus not have all valence electrons bound to carbon (e.g. $\ce{Ti^{IV}C_{1-x}^{-IV}(e^-)_{4x}}$). The overall story is that at least for methanides, the distinction between "ionic/saline" and "metallic/interstitial" carbides is actually not sharp.
Reference
A. I. Avgustinik; G. V. Drozdetskaya; S. S. Ordan'yan (1967). "Reaction of titanium carbide with water". Powder Metallurgy and Metal Ceramics. 6 (6): 470–473. doi:10.1007/BF00780135. S2CID 134209836
The following is multiple choice question (with options) to answer.
Interstitial carbides are produced by the reaction of most transition metals at high temperatures with what element? | [
"oxygen",
"hydrogen",
"nitrogen",
"carbon"
] | D | temperatures with electropositive metals such as those of groups 1 and 2 and aluminum produces ionic carbides, which contain discrete metal cations and carbon anions. The identity of the anions depends on the size of the second element. For example, smaller elements such as beryllium and aluminum give methides such as Be2C and Al4C3, which formally contain the C4− ion derived from methane (CH4) by losing all four H atoms as protons. In contrast, larger metals such as sodium and calcium give carbides with stoichiometries of Na2C2 and CaC2. Because these carbides contain the C4− ion, which is derived from acetylene (HC≡CH) by losing both H atoms as protons, they are more properly called acetylides. As discussed in Chapter 21 "Periodic Trends and the ", Section 21.4 "The Alkaline Earth Metals (Group 2)", reacting ionic carbides with dilute aqueous acid results in protonation of the anions to give the parent hydrocarbons: CH4 or C2H2. For many years, miners’ lamps used the reaction of calcium carbide with water to produce a steady supply of acetylene, which was ignited to provide a portable lantern. The reaction of carbon with most transition metals at high temperatures produces interstitial carbides. Due to the less electropositive nature of the transition metals, these carbides contain covalent metal– carbon interactions, which result in different properties: most interstitial carbides are good conductors of electricity, have high melting points, and are among the hardest substances known. Interstitial carbides exhibit a variety of nominal compositions, and they are often nonstoichiometric compounds whose carbon content can vary over a wide range. Among the most important are tungsten carbide (WC), which is used industrially in high-speed cutting tools, and cementite (Fe3C), which is a major component of steel. Elements with an electronegativity similar to that of carbon form covalent carbides, such as silicon carbide (SiC; Equation 22.15) and boron carbide (B4C). These substances are extremely hard, have high melting points, and are chemically inert. For example, silicon carbide is highly resistant to chemical attack at temperatures as high as 1600°C. Because it also maintains its strength at high temperatures, silicon carbide is used in heating elements for electric furnaces and in variable-temperature resistors. |
SciQ | SciQ-39 | species-identification, microbiology, microscopy
Title: Identification of protozoa under microscope I observed maybe Protozoa from standing FRESH water and from slowly flowing FRESH water. I am complete dilettante. Can you tell what these creatures are?
https://www.youtube.com/watch?v=6D5ck3zNJzA&t=474s
Thank you.
Added picture for to be more specific At first glance, the organisms may hold the appearance of protozoans like ciliates. However, I am of the belief that these 'totally tubular' micro organisms are in fact diatoms.
The diatoms are a diverse range of eucaryotic microalgae which comprise a large percentage of the phytoplankton group. (Diatomaceous earth is the residual remains of their calcareous walls)
They are likely diatoms because of their apparent hard membrane, and slight brown-green pigment, typical of heterokont diatoms.
I would be unable to specify the organism to family level. However, you may wish to complete your investigation by looking under the order 'Pennales'.
For general information regarding the Diatoms, you may visit https://en.wikipedia.org/wiki/Diatom
Morphology and description available from: https://books.google.co.uk/books?id=xhLJvNa3hw0C&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
Good luck
The following is multiple choice question (with options) to answer.
Fungus-like protist saprobes play what role in a food chain and are specialized to absorb nutrients from nonliving organic matter, such as dead organisms or their wastes? | [
"decomposers",
"aphids",
"fluxes",
"Soil"
] | A | Agents of Decomposition The fungus-like protist saprobes are specialized to absorb nutrients from nonliving organic matter, such as dead organisms or their wastes. For instance, many types of oomycetes grow on dead animals or algae. Saprobic protists have the essential function of returning inorganic nutrients to the soil and water. This process allows for new plant growth, which in turn generates sustenance for other organisms along the food chain. Indeed, without saprobe species, such as protists, fungi, and bacteria, life would cease to exist as all organic carbon became “tied up” in dead organisms. |
SciQ | SciQ-40 | molecular-biology, dna, molecular-genetics
Additionally, there's regulation of protein biosynthesis at the ribosome, which often complexes with other molecules in complicated ways to ensure an additional layer of tuning of how much protein is produced, and how quickly.
There are many, many other known levels of regulation. There also remain many unknown mechanisms of regulation, which scientists are busy with uncovering and understanding as we speak.
EDIT: What dictates which protein to synthesize at a given time? The history and present identity of a cell. By identity, I mean its state regarding regulation of its own gene expression, as well as other things.
The following is multiple choice question (with options) to answer.
What are the sites of protein synthesis or assembly? | [
"chromosomes",
"chloroplasts",
"plasma",
"ribosomes"
] | D | Ribosomes are small organelles and are the sites of protein synthesis (or assembly). They are made of ribosomal protein and ribosomal RNA, and are found in both eukaryotic and prokaryotic cells. Unlike other organelles, ribosomes are not surrounded by a membrane. Each ribosome has two parts, a large and a small subunit, as shown in Figure below . The subunits are attached to one another. Ribosomes can be found alone or in groups within the cytoplasm. Some ribosomes are attached to the endoplasmic reticulum (ER) (as shown in Figure below ), and others are attached to the nuclear envelope. |
SciQ | SciQ-41 | cell-biology, meiosis, mitosis
Title: Is the cell cycle applicable to meiosis as well, or just mitosis? All the diagrams I can find, show the cell cycle as having G1 phase (growth 1), S phase (DNA replication), G2 (growth 2) before the Mitotic phase (mitosis + cytokinesis).
Is there an equivalent "cell cycle" for meiosis, since the chromosomes in parent cell in meiosis also having "double" the genetic material prior to cell division (presumably from DNA replication too)?
Is it simply the same cell cycle as mitosis but with a Meiotic phase instead of Mitotic?
If so, would appreciate if anyone had a diagram :) Thanks! The cell cycle is only associated with mitosis. The cell cycle is the normal process of cell division with which cells can indefinitely increase their number by cyclically repeating the process. When a cell goes through the cycle, the result is two cells that are genetically identical.
Meiosis is a special type of cell division (which can occur only in eukaryotes) that produces cells that are not genetically identical to the initiating cell. The number of chromosomes in each of the resulting cells is half the number that were in the initial cell. (These haploid cells can later participate in fertilization, producing a cell with the original number of chromosomes.) Many of the steps of meiosis are similar to the steps involved in mitosis, but overall the process is more complex. Since meiosis reduces the number of chromosomes, it cannot be repeated and so does not take part in a cell division cycle.
The following is multiple choice question (with options) to answer.
What must replicate in the cell cycle before meiosis i takes place? | [
"sperm",
"cell walls",
"dna",
"meiotic fluid"
] | C | Meiosis I begins after DNA replicates during interphase of the cell cycle. In both meiosis I and meiosis II , cells go through the same four phases as mitosis - prophase, metaphase, anaphase and telophase. However, there are important differences between meiosis I and mitosis. The eight stages of meiosis are summarized below. The stages will be described for a human cell, starting with 46 chromosomes. |
SciQ | SciQ-42 | geophysics, earthquake
Title: Frequency of earthquakes Are earthquakes getting less frequent across the centuries? I know that more seismic stations have register more earthquakes in the last century, but that doesn't imply there were more. I am interested on the geophysical side of it.
The logic is that things settle down, so there is less stuff to shuttle. Add to it that the earth (at its core) get colder with the passage of time. There is no evidence that the global earthquake frequency has changed significantly over that last few centuries. Because the physical mechanism responsible for earthquakes is motion along faults, we believe there have been earthquakes for as long as the earth has had a crust and lithosphere comparable to today.
The oldest continental rocks dated, and ample geological evidence, indicate that plate tectonics has been ongoing for over 4 billion years. There may have been some variation in the rate of tectonic processes over time, but there is no evidence that plate tectonics is 'slowing down' because the earth is cooling.
You also should not assume that the temperature of the earth's core has been decreasing over this time. The radioactive decay and gravitational differentiation of the core could provide heat source in the earth's interior.
Prior to the formation of the crust, billions of years ago, the processes of the primordial earth would have been different than the processes responsible for earthquakes today.
The following is multiple choice question (with options) to answer.
What phenomenon is primarily the result of plate tectonic motions? | [
"tsunamis",
"volcanoes",
"earthquake",
"eruption"
] | C | Earthquakes are primarily the result of plate tectonic motions. What type of stress would cause earthquakes at each of the three types of plate boundaries?. |
SciQ | SciQ-43 | neuroscience, neuron
Note in this paragraph they are literally talking about 5 specific pairs of cells, where they trace both cells in EM. This is an exhausting process. The presynaptic cells were one basket cell, three dendrite-targeting cells, and one double bouquet cell. The post-synaptic cells were all pyramidal cells except one was a spiny stellate cell. In the five pairs they found 15, 17, 8, 3, and 10 connections. Of course they could have missed some, too.
Tamas, G., Buhl, E. H., & Somogyi, P. (1997). Fast IPSPs elicited via multiple synaptic release sites by different types of GABAergic neurone in the cat visual cortex. The Journal of physiology, 500(3), 715-738.
The following is multiple choice question (with options) to answer.
What is a group of neuron cell bodies in the periphery called? | [
"gangism",
"ganglion",
"crystals",
"organism"
] | B | Ganglia A ganglion is a group of neuron cell bodies in the periphery. Ganglia can be categorized, for the most part, as either sensory ganglia or autonomic ganglia, referring to their primary functions. The most common type of sensory ganglion is a dorsal (posterior) root ganglion. These ganglia are the cell bodies of neurons with axons that are sensory endings in the periphery, such as in the skin, and that extend into the CNS through the dorsal nerve root. The ganglion is an enlargement of the nerve root. Under microscopic inspection, it can be seen to include the cell bodies of the neurons, as well as bundles of fibers that are the posterior nerve root (Figure 13.19). The cells of the dorsal root ganglion are unipolar cells, classifying them by shape. Also, the small round nuclei of satellite cells can be seen surrounding—as if they were orbiting—the neuron cell bodies. |
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