source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-1301 | evolution, homework
Title: Can someone help me analyze this article? I need to read this article — "Beyond the rainbow" by
Marie-Claire Koschowitz et al., for an exam.
Following are some questions for which I could not figure the answer out after reading.
1) Why does this miniaturization necessitates insulation ? Following is quote from article: "For fast-growing, presumably warm- blooded animals , such miniaturization would only have been possible with sufficient body insulation. "
2) Dinosaurs suppose to have tetrachromacy. The article mentions "dinosaurs were endowed with the highly differentiated color vision of birds". Does this mean Dinosaur's "inherited" their tetrachromacy from birds ? Why does the article mention reptiles before that ? Are birds reptiles ?
3) The article starts talking about how mammals develop fur and lost their highly differentiated color vision because they gave up structural color signaling. What is the direct connection between mammals and the dinosaurs ? I don't see the parallel here....why bring the mammals into the discussion ?
4) What is the connection between pennaceous feather and planar feathers ?
Any or all questions answered is welcome ! Thanks ! I will answer the questions one by one-
Why does this miniaturization necessitates insulation ?
An organism's volume determines the total amount of heat that can be stored. The loss (exchange) of heat between the body and external environment mainly occurs on the skin's surface. Hence, body volume determines how much heat is stored, while body surface determines how fast that heat is dissipated to the environment. Volume increases with a power of three with radius, while surface increases with a power of two. Hence, smaller animals have large surface-to-volume ratios, which decreases rapidly with body size. Hence, small animals will dissipate relatively more heat per unit of time.
Dinosaurs suppose to have tetrachromacy. The article mentions "dinosaurs were endowed with the highly differentiated color vision of birds". Does this mean Dinosaur's "inherited" their tetrachromacy from birds ?
No, birds are the closest living relatives to dinosaurs, and birds can be said to have inherited tetrachromacy from dinosaurs - see the cladogram below.
The following is multiple choice question (with options) to answer.
A person discovers a dinosaur skeleton in their backyard under a lot of dirt. The skeleton is lacking the bright whiteness of bones, because it is | [
"filled with beer",
"covered in salt",
"trapped in stone",
"smooth with wires"
] | C | fossils are formed when layers of sediment cover the remains of organisms over time |
OpenBookQA | OpenBookQA-1302 | astronomy, everyday-life, popular-science, climate-science
It is for much the same reason that Winter is colder than Autumn, even though they have the same amount of daylight hours.
The following is multiple choice question (with options) to answer.
It becomes cold enough for heavy clothing in December in the northern hemisphere because | [
"our planet's axis is tilted",
"Mercury's axis is tilted",
"the gravitational pull of Pluto on the southern hemisphere",
"lyrics about winter by popular musicians always mention bundling up"
] | A | Earth 's tilt on its axis causes seasons to occur |
OpenBookQA | OpenBookQA-1303 | electric-circuits, electric-current, electrical-resistance, batteries, short-circuits
Title: The importance and the role of a switch in an electrical circuit There is this simple test:
Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed:
a] The brightness of $A$ and $B$ remains the same, while $C$ goes out.
b] The brightness of $A$ and $B$ remains the same, while that of $C$ is halved.
c] The brightness of $A$ and $B$ decreases while $C$ goes off.
d] The brightness of $A$ and $B$ increases while $C$ goes off.
For my opinion the answer to this question is D because the switch (which has a resistance of $0\, \Omega$ has a node connected before the third bulb C) that "interrupts" the circuit. But, going into detail, according to Kirchhoff's first law the current should also go on the third bulb as in the first red node it divides into two currents $I_1$ and $I_2$. The current $I_1$ goes for example in the key $S$ and $I_2$ in the third bulb. The key and the third bulb have the same potential difference. I believe that the current $I_2$ passes through the third bulb but the current passing through it is so small that it does not turn on.
I made a point. When an individual is operated on at the heart and puts a by-pass (a bridge), blood will flow on the tube that detects the by-pass and the occluded artery (the third bulb) where blood will flow slowly, over time it will atrophy.
If the circuit were like the one drawn in the picture I would answer the b).
My question is: I have not very clear the rule of a switch in a eletric-circuit.
In fact, I find it difficult to give an answer to the following image.
The following is multiple choice question (with options) to answer.
a switch turns something with a power source on because: | [
"the circuit is opened",
"the light turns off",
"the insulation adds current",
"a piece of copper closes the circuit"
] | D | a closed circuit has continuous path |
OpenBookQA | OpenBookQA-1304 | organic-chemistry, biochemistry, color, electromagnetic-radiation
Title: How does UV affect skin colors in dark-skinned people? Skin color is one of the things one would rather not ask anything about! Only in humans, it can vary from very dark brown to pale pink. In darker-skinned people, the color is mainly due to melanin, which is produced by melanocytes.
There are three types of melanin: eumelanin, pheomelanin, and neuromelanin. Eumelanin is the most common; so it must be the reason of the dark skin of the dark-skinned. And that's true, since the two major groups of eumelanin are black and brown species.
The first ray produced by sun that comes to mind when you think about affecting the attributes of skin is UVA, since it penetrates most into the skin (Even though its energy is lesser than UVB). So, when I attach these two together I reach the fact that if UV rays do not cause free radicals they will eventually change the skin's color. (This is what is mostly believed and its effect on natural selection is impossible to hide)
Now, I give up. How does UV do to the skin that makes it darker? This must be very easy, huh? What am I missing? There is a journal article almost exactly about the title question, Mechanisms of Skin Tanning in Different Racial/Ethnic Groups in Response to Ultraviolet Radiation Journal of Investigative Dermatology (2005) 124, 1326–1332.
However, the body of the question assumes that eumelanin changes color. Instead, the article finds that melanin gets closer to the surface of the skin, and the degree to which this effect occurs varies with race/ethnicity.
The following is multiple choice question (with options) to answer.
Jamaican natives have a dark skin tone do to | [
"lack of nutrients",
"camouflage",
"solar radiation",
"their diet"
] | C | living in an environment causes an organism to adapt to that environment |
OpenBookQA | OpenBookQA-1305 | ecology, population-dynamics, ecosystem, antipredator-adaptation, predation
I would also like to talk about other things that might be of interest in your model (two of them need you to allow evolutionary processes in your model):
1) lineage selection: predators that eat too much end up disappearing because they caused their preys to get extinct. This hypothesis has nothing to do with some kind of auto-regulation for the good of species. Of course you'd need several species of predators and preys in your model. This kind of hypothesis are usually considered as very unlikely to have any explanatory power.
2) Life-dinner principle. While the wolf runs for its dinner, the rabbit runs for its life. Therefore, there is higher selection pressure on the rabbits which yield the rabbits to run in average slightly faster than wolves. This evolutionary process protects the rabbits from extinction.
3) You may consider..
more than one species of preys or predators
environmental heterogeneity
partial overlapping of distribution ranges between predators and preys
When one species is absent, the model behave just like an exponential model. You might want to make a model of logistic growth for each species by including $K_x$ and $K_y$ the carrying capacity for each species.
Adding a predator (or parasite) to the predator species of interest
... and you might get very different results.
The following is multiple choice question (with options) to answer.
A lone fox is searching for its next meal in a meadow that used to be bountiful with food. This season, though, rabbits have all been eaten up and the field is dry and barren. The fox may | [
"fly",
"speak",
"starve",
"float"
] | C | loss of resources has a negative impact on the organisms in an area |
OpenBookQA | OpenBookQA-1306 | human-biology, neuroscience, evolution
Title: Why have humans evolved much more quickly than other animals? Humans have, in a relatively short amount of time, evolved from apes on the African plains to upright brainiacs with nukes, computers, and space travel.
Meanwhile, a lion is still a lion and a beetle is still a beetle.
Is there a specific reason for this? Do we have a particular part of brain that no other animal has? This question appears to address at least two distinct concepts:
the "speed" of evolution
whether there is some "end goal" that evolution seeks
I will provide an explanation of each separately below:
The Speed of Evolution
The speed at which a species evolves—that is, the speed at which it acquires new heritable characteristics—can be affected by numerous factors. Among the most obvious which come to mind are:
existing population size
reproductive cycle rate
number of offspring
offspring survival rate
environmental demands
The following is multiple choice question (with options) to answer.
A lion is hunting antelope. The antelope are fast, faster than the lion expected. To eat today, the lion needs | [
"to find more water",
"to catch up to it",
"to enjoy its day",
"to wear better shoes"
] | B | if an organism 's prey moves quickly then that organism may need to move quickly to catch its prey |
OpenBookQA | OpenBookQA-1307 | climate-change, geography, rivers, rainfall, agriculture
Today Climate change and its consequences are some of the biggest challenges facing Humanity, with water scarcity being the big factor in Sub-Sahara Africa.
By Ultimately raising the Rainfall in the entire Southern Africa, through the managed and controlled filling and utilization of the Natural 30 000 - 60 000 square km of evaporation pans more regularly, will this not lower the extreme temperatures (day and night temperatures due to water absorbing much of the daytime heat and releasing it during the night) and drought patterns Southern Africa has experienced, and by all predictions are bound to worsen and could become more extreme?
In effect, creating a second Okavango Delta, but considerably bigger - large parts of Chobe.
A study of such a magnitude will need large amounts of research in multidisciplinary sciences, from Archaeology to Agriculture to Economics, and a much broader field of expertise - the biggest being Politics!
Could such a mammoth project not be but one small answer to a much bigger Climate Change challenge facing the Earth? (and ultimately send a bit of rain to my little piece of land in the Waterberg in the long dry winter months when we receive those dry West Winds - and fires become a serious hazard - simply by adding a bit of moisture from the vast pans Botswana are so blessed with!)
My mind has been going in circles as to the feasibility of such a mammoth, yet so cheap and easily implementable idea?
Any ideas? We agree that additional evaporation enhances energy transport from the surface to the atmosphere and intensifies the hydrological cycle and cloud formation, and that some of the most serious climate change issues such as:
The following is multiple choice question (with options) to answer.
As the air becomes more arid it contains | [
"oxygen",
"rain",
"less humidity",
"more static"
] | C | as dryness increases in an environment , the available water in that environment will decrease |
OpenBookQA | OpenBookQA-1308 | geophysics, sedimentology
Title: Does dirt compact itself over time? If so, how does this happen? If I were to bury something 10 feet (~3 metres) underground, with loose soil on top, would the ground naturally compact itself over time, until whatever I had buried has dirt tightly pressing against it on all sides?
What if I buried it 50 feet (~15 metres) underground?
If it exists, what is this compaction process called and how does it happen? Soil is a collection of various sized minerals grains, of various types of minerals produced by the weathering of rock. Typical soil minerals are clays, silts and sands.
The properties and behavior of different soil types depends of the composition of the soil: the proportion of clays, silts and sand in a soil. Sandy soils are well draining and clayey soils are sticky.
Between the grains of minerals that comprise a soil are spaces, called pores or pore spaces. The pores can be filled with either water or air, depending the location of water tables and wetting events like rain, snow melts or other forms of water inundation.
The density of a soil is dependent on the degree of compaction of the soil. For to a soil to be compacted, a stress has to be applied to the soil to realign the grains of soil which reduces the total volume of the pores and reduces the amount of air within the pores.
Consolidation of a soil occurs when pore space is reduced and water in a soil is displaced due to an applied stress.
Regarding having something buried and soil compacting around it over time, yes that will occur but it is a question of how much stress the soil experiences, the duration of time and the nature of the soil - sandy or clayey. Something buried for a day without any stresses not much will happen. But, something buried for thousands of years with people and animals walking over it, rain falling on the soil, vibrations from nearby human activity and an occasional earthquake all add to the stresses the soil will experience and increases the degree of compaction or consolidation over time.
The following is multiple choice question (with options) to answer.
A person has sand in their shoe from the beach, and they dump the sand out at their doorstep many miles away. The sand could end up back on that beach if | [
"magic creatures move it",
"someone goes to the zoo",
"a large gust passes",
"people wish for it"
] | C | wind carries sand from one place to another place |
OpenBookQA | OpenBookQA-1309 | ecology
Title: Statement about Tropical Rainforests I made a statement about tropical rainforests, and I want to know if it's somewhat true or not:
The soil in tropical rainforests is not exceptionally fertile, because it contains few minerals. The reason that a tropical rainforest has a huge amount of vegetation is because of the quick mineralisation. If a dead leaf falls onto the ground, it immediately gets turned into minerals, which the plants immediately use for sustaining theirselves There are many websites which describe this phenomenon. They all seem to confirm the basic premise of the question: in tropical rain forests most of the minerals are held in the biomass and rapid decomposition contributes to the recycling of these nutrients for new growth. One example is here.
Tropical rainforests are noted for the rapid nutrient cycling that occurs on the ground. In the tropics, leaves fall and decompose rapidly. The roots of the trees are on the surface of the soil, and form a thick mat which absorbs the nutrients before they reach the soil (or before the rain can carry them away). The presence of roots on the surface is a common phenomenon in all mature forests; trees that come along later in succession win out in competition for nutrients by placing their roots over top of the competitors, and this pattern is seen in the temperate rainforest as well. What does not occur in the temperate rainforest, however, is a rapid cycling of nutrients. Because of the cold conditions and the acidity released by decomposing coniferous needles on the forest floor, decomposition is much slower. More of the nutrients are found in the soil here than would be the case in a tropical forest, although like the tropical forest most of the nutrients are held in the plants and animals themselves.
I looked for actual evidence of these differences in rates of decomposition and I found this:
Salinas, N. et al. (2011) The sensitivity of tropical leaf litter decomposition to temperature: results from a large-scale leaf translocation experiment along an elevation gradient in Peruvian forests. New Phytologist 189: 967-977
The following is multiple choice question (with options) to answer.
If a tree falls in the forest, then gets covered in mud, it might form : | [
"future imprints in rock",
"Houses for hairy sasquatch",
"charmin brand toilet paper",
"Footprints on a beach"
] | A | An example of a fossil is a paw print in rock |
OpenBookQA | OpenBookQA-1310 | evolution, zoology, adaptation
One answer that came to mind is domestic animals - the horse and dog in prehistory, the cat in ancient Egypt, etc. That seems too obvious on one hand, and on the other hand may not really be an answer, as there seems to be no indication that pre-domestic animals were endangered by humans in any meaningful way. Are there animals that have significantly adapted themselves to surviving as wild animals in human-influenced environments? Note: This is an answer to the last line of your question.
A classical example of animals adapting to the influence of humans on their environment is the adaption of the Peppered Moth.
Here is a brief summary:
The peppered moth was originally a mostly unpigmented animal (<1800). During the industrial revolution in the southern parts of the UK a lot of coal was burned. This led to soot blackening the countryside. Soon afterwards, a fully pigmented variety was first observed. Only a hundred years later, in 1895, this pigmented variety almost completely displaced the unpigmented variety.
It has been shown that the pigmentation is under strong selective pressure as birds hunt these moths. Since birds rely on their visual system to detect their prey, the variety that blends in with its environment (=camouflage) has a selective advantage over the variety that stands out.
As pointed out by Tim in the comments, since the 1970s there has been a rapid reversal with unpigmented animals being more abundant. As far as I understand, it is accepted that this reversal is due to a decrease in human induced air pollution leading to less sooty barks on trees which makes the unpigmented variety harder to prey upon.
Addendum: genetic basis of adaption
In a beautiful recent study, the causal mutation for the pigmented, or melanic, variety was identified: A ~9kb transposon insertion in the first intron of the gene cortex. The authors calculate that this mutation happened in the year 1819, a few years after the industrial revolution was in full swing. The interpretation is that due to sooty tree bark this mutation, causing pigmented moth, was under strong selection.
The following is multiple choice question (with options) to answer.
Camouflage is used by entities for hunting | [
"air",
"trees",
"vittles",
"water"
] | C | An example of camouflage is an organism looking like leaves |
OpenBookQA | OpenBookQA-1311 | = ",Count[Drop[branches,gen],_Real,\[Infinity]]/4" "" ""Length = ",SetAccuracy[Count[Drop[branches,gen],_Real,\[Infinity]]/4*(Norm[{{pt1[[1]],0.5},{0,0}}]^gen),3]}],18],Gray],{2.3,-1.8}]},{Inset[Style[Text@TraditionalForm@Style[Row[{"Polynomial Trees by Bernat Espigulé"}],18],Gray, Opacity[0.4]],{2.3,-2}]}},PlotRange->{{-1.7,3.7},{-2.1,1.5}},ImageSize->{1000,600},Background->Black]],{{th,0.025,"Thickness"},0.005,0.185},{{gen,12,"Generations"},Range[1,16], ControlType -> SetterBar},{{pt1,{0.5,0.5}},{-0.5,0.5},{0.5,0.5},Locator}]Jurassic Trees
The following is multiple choice question (with options) to answer.
If a tree is separated from it's roots it will | [
"run away",
"expire",
"have a party",
"get stronger"
] | B | if a tree is cut down then that tree will die |
OpenBookQA | OpenBookQA-1312 | ocean, ocean-currents, tides
Physical effects, then, are likely to include direct effects on current speed, sediment, and stratification.
The obvious possible biological effect is from collisions. This is not my field, but as I understand it no effect is likely on small fish populations from collisions, although individuals may be affected. Collision risk for large animals (e.g. sharks and marine mammals) and for diving birds is a topic of active research, and is likely (especially for mammals) to depend on their behaviour around the devices. No large animal collisions have been reported on any of the prototypes undergoing testing so far.
A good review of possible effects on benthic organisms is provided by Shields et al (2011). These may include,
The following is multiple choice question (with options) to answer.
Some human activities may create brackish like | [
"swimming tubs",
"buildings",
"ships",
"cars"
] | A | water is often brackish in an estuary |
OpenBookQA | OpenBookQA-1313 | homework, plant-physiology, plant-anatomy
and 'Vascular Plants = Winning! - Crash Course Biology #37'
https://youtu.be/h9oDTMXM7M8?t=373
[5] Osmosis (water compensating solutes) "In Da Club - Membranes & Transport: Crash Course Biology #5"
https://youtu.be/dPKvHrD1eS4?list=PL3EED4C1D684D3ADF&t=148
Ian (and dad <= all errors and approximations are his :) ).
The following is multiple choice question (with options) to answer.
To see an example of xylem in work | [
"organize flowers in a bouquet",
"put a rose in food dye",
"pull a plant from the root",
"poor water on a plant"
] | B | xylem carries water from the roots of a plant to the leaves of a plant |
OpenBookQA | OpenBookQA-1314 | oxidation-state
Title: Does plant material oxidize from 02 gas (air or solved in water) and/or oxygen in H20? https://en.m.wikipedia.org/wiki/Curing_of_tobacco
Hi
This is my first time growing tobacco for fun, pleasent green at home, to make snuff for personal use and maybe save som money.
Ive been reading a bit on wiki, it says oxidization is what makes tobacco cure/age/mature take out the harsh.
Im wondering about if the oxidization of caratenoids and chlorophyll in tobacco curing is from O2 in air (or solved in water) and/or from O in H2O itself?
From what i remember, from school and various archeology programs on tv, wood in sea bed with no O2 solved in it doesnt rot but metals will rust. ?
At what relative humidity at room temperature will tobacco leaves sealed in a jar (in fall and winter the relative humidity in my apartment will drop too much for curing tobacco, i guess) cause them to cure? If air is required, how much?
/Johan Okay first, it's the oxygen in the air that causes oxidation, also dissolved oxygen in water, but if you let your tobacco get wet enough for the latter to be significant you will be getting more rot than curing ...
Anyway, I don't think a sealed jar would be a good idea. Ammonia build-up, wet rot, etc would tend to be an issue.
You could build a proper curing/fermenting kiln to cure the leaf, there's DIY instructions here: https://www.seedman.com/wkiln.htm for one type. But if you're using the finished product for dry snuff rather than smoking or chewing, you might not be too bothered about the taste/smell so careful fermenting is probably not that important to you. Then easiest is to just hang them somewhere like the garage and spray them with a plant mister when they get too dry like this guy: https://dengarden.com/gardening/Tobacco-Growing-and-Curing-at-Home or if it gets too cold where you live to use the garage, in a closet, wooden box or linen chest.
The following is multiple choice question (with options) to answer.
What makes sure that the tips of your toes have enough of the gas that plants put off? | [
"your circulatory system",
"your pancreas",
"warm socks",
"your nervous system"
] | A | the circulatory system transports blood throughout the body |
OpenBookQA | OpenBookQA-1315 | electricity, electric-circuits, electrons
Title: Do electrons coming out of a lightbulb (and going back into the circuit) slow down? Do electrons coming out of a lightbulb (and going back into the circuit) slow down?
The electrons enter the light bulb filament with relatively high kinetic energies. As they travel through the filament they collide with metal atoms transferring much of their kinetic energy to the metal. This energy raises the temperature of the metal. The metal in turn radiates this energy as electromagnetic waves, many in the visible spectrum.(Source 1)
and
Each light bulb results in a loss of electric potential for the charge. This loss in electric potential corresponds to a loss of energy as the electrical energy is transformed by the light bulb into light energy and thermal energy. (Source 2)
The following is multiple choice question (with options) to answer.
The production of lightbulbs effects the | [
"brain",
"blood cells",
"air",
"ocean"
] | D | some light bulbs convert electricity into light and heat energy |
OpenBookQA | OpenBookQA-1316 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
A quick way to adjust the formation of portions of the crust of the earth is for it to | [
"experience trembling",
"make believe",
"fall down",
"fly away"
] | A | an earthquake changes Earth 's surface quickly |
OpenBookQA | OpenBookQA-1317 | electrochemistry, conductivity
After Kohlrausch had developed his method of measuring the electrical
conductance of solutions by means of an alternating current bridge, he
undertook with the aid of Holborn and Diesselhorst’ the determination
of the specific conductance of seven standard reference solutions in
absolute units in order that the results might be available to himself
and to other experimenters for the calibration of conductance cells.
For this purpose they used two cells whose cross sectional areas, a,
and length, l, were determined mechanically. The cell constant,
l/a, could then be computed in absolute units (cm$^{-1}$) from the measured dimensions.
The cell constants of a considerable number of other cells with
sealed-in electrodes of the usual type were determined electrically by
comparison with the primary cells by measurements of resistance when
filled with a common solution. These cells, whose cell constants were
thus determined indirectly, were then used for the determination of
the specific conductance of the seven standard reference solutions at
approximately 0, 9, 18, 27 and 36 C. The specific conductance of each
of these solutions for every degree between 0 and 36 C was obtained by
interpolation. No actual measurements were made at either 20 or at
25’. The water-bath used to fix the temperature of the cells was not
provided with an automatic thermostatic control. The majority of the
data on conductance in the literature are based on the values ascribed
to these standard reference solutions by Kohlrausch, especially the 1
N and 0.1 N potassium chloride solutions.
In the original paper by Kohlrausch, Holborn and Diesselhorst it is
stated that the normal potassium chloride solution was prepared by
dissolving 74.555 g. of potassium chloride weighed in air and making
up to 1 liter at 18 C. The 0.1, 0.02, and 0.01 normal solutions were
prepared by dilution by volume. The book “Das Leitvermogen der
Elektrolyte” by Kohlrausch and Holborn, which was published in the
same year as the paper referred to, contains alternative directions
for the preparation of these solutions by weight. This book has
probably been used by other experimenters more than the original paper
because it is more generally available.
The following is multiple choice question (with options) to answer.
H2O allows for the conduction of | [
"electrical potential",
"land",
"neurons",
"people"
] | A | water is an electrical conductor |
OpenBookQA | OpenBookQA-1318 | 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.
seeds may grow when | [
"ingested",
"roasted",
"left alone",
"placed underground"
] | D | seeds may sprout when buried in soil |
OpenBookQA | OpenBookQA-1319 | structures
Title: Siding for Industrial Shed: Rain protection vs Ventilation When building a 12 m tall industrial shed with a peaked roof it is desirable that the sides of the shed should stay open as much as possible for ventilation / safety / access concerns.
On the other hand, an entirely open side from top to bottom might cause a lot of rain exposure when the rain comes in angled?
Is there a trade-off possible? Perhaps to enclose sides till a certain distance below the roof edge? Any heuristics about how much? (I've shown 4000 mm in the sketch below)
The contents inside the shed are relatively robust / waterproof & hence absolute rain protection is not needed. This will very much depend on the exposure of the building to wind as this is what will drive the rain in at an angle. So you really need to consider the prevailing wind direction and how sheltered the building is by other nearby structures etc.
If may be that if the prevailing wind direction is fairly consistent you can have one side more open than another.
Another option is to have panels which can be folded down when required eg if you have 4000mm of fixed cladding, you could have the same in fold-down form (this arrangement is fairly common in barns).
Also it depends what access you need obviously forklifts will need more height clearance than pedestrians.
You could also consider using strip curtains for at least part of the height.
The following is multiple choice question (with options) to answer.
What will be more available in an area when rain is common? | [
"dirt",
"air",
"h2o",
"fire"
] | C | a desert environment has low rainfall |
OpenBookQA | OpenBookQA-1320 | orbit, earth, eccentric-orbit, eccentricity
Basically, this map shows the height of the geoid (the idealized sea level without the effects of tides and currents) with respect to the WGS84 reference ellipsoid of revolution (semi-major axis 6,378,137 m, semi-minor axis 6,356,752.314 m). The differences are mostly less than 100 meters, and are caused by the irregular distribution of mass inside the Earth itself.
Now, some studies show that the Earth's shape could be slightly better modeled by a triaxial ellipsoid, and one could try to model the equator as an ellipse, and the Earth as a triaxial ellipsoid, however, even with a best-fit triaxial, we would still need geoid corrections for the irregular mean sea level, let alone topography, and geodetic computations would be more complex on a triaxial. Other funny models and names have come up over time, like a pear-shaped (because of a slight bulge in mid southern latitudes) model as a best-fit shape. But if you look at the map above, good luck visually finding the pear shape in there, or other mathematically modelizable aspects of these bumps. We are talking about very subtle differences here, that do not necessarily need to be taken into account for most purposes when describing the general shape of the Earth.
So depending on how you consider the shape of the equator (i.e. by topography and ocean floor, or sea level) you will arrive at a shape that is mostly circular with irregular bumps along the way. There is no authoritative agreement that I know of about an eccentricity of the equator. For instance, This study proposes a flattening of about 70 meters for the equator's ellipse, This article on Encyclopaedia Britannica proposes 80 meters.
For the Earth's orbit, for the sake of this comparison, we can use an best-fit ellipse of 149.598 million km by 149.577 million km. Of course, that is only a idealized ellipse, the real movement of the Earth in the Solar System is more complex.
The following is multiple choice question (with options) to answer.
The Earth's topography varies widely from the deepest trenches to the tallest | [
"tales",
"trees",
"pinnacle",
"buildings"
] | C | the surface of the Earth contains mountains |
OpenBookQA | OpenBookQA-1321 | physiology, ichthyology
Salmon use to deal with the NaCl fluxes driven by the gradients between the salmon and its surroundings. In their gill epithelial cells, salmon have a special enzyme that hydrolyzes ATP and uses the released energy to actively transport both Na+ and Cl- against their concentration gradients. In the ocean, these Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the salmon's blood into the salt water flowing over the gills, thereby causing NaCl to be lost to the water and offsetting the continuous influx of NaCl. In fresh water, these same Na+-Cl- ATPase molecules 'pump' Na+ and Cl- out of the water flowing over the gills and into the salmon's blood, thereby offsetting the continuous diffusion-driven loss of NaCl that the salmon is subject to in fresh water habitats with their vanishingly low NaCl concentrations.
Reference
Reference
The following is multiple choice question (with options) to answer.
Gills are used to breath water by what? | [
"salmon",
"fishing boats",
"mammals",
"penguins"
] | A | gills are used for breathing water by aquatic animals |
OpenBookQA | OpenBookQA-1322 | newtonian-mechanics, rotational-dynamics, rigid-body-dynamics, gyroscopes, precession
Given that the two gyroscopes are on a rigid rod the tendency to rise will transfer to the center. So yeah: a scale will show a lower weight.
Of course, this does not provide a way to get lift for free: in order to push you need leverage; your feet need to be firmly on the ground. (Compare pushing a large piece of furniture: if your feet don't have grip then you will only push yourself backward instead of moving that piece of furniture.)
The following is multiple choice question (with options) to answer.
Which weight has the most resistance when being picked up? | [
"3 pound purple weight",
"2 pound pink weight",
"5 pound green weight",
"8 pound blue weight"
] | D | as the resistance to something increases , how easilty that something can be done will decrease |
OpenBookQA | OpenBookQA-1323 | fluid-dynamics, density, buoyancy
IN ANSWER TO THE QUESTION IN YOUR EDIT
Intuitively you would think that increasing the pressure of the air increases the downward force on the block, making it sink lower in the water, but this is not the case. In both cases what happens to the block does not depend on the pressure of the air but the pressure gradient in the air. If the pressure is uniform throughout the air space, an increase or decrease has no effect on the depth at which the object floats in the water. But if there is a pressure gradient (which necessarily increases downwards) then an increase in the average pressure makes the object rise up in the water, and a decrease makes it sink lower.
Explanation
The explanation is similar to that in Why does a helium filled ballon move forward in a car when the car is accelerating?
The forces on the block are initially balanced. The vertical forces are the weight $W$ of the block and the pressure-forces $F_1$ of the air on the upper face and $F_2$ of the water on the lower face of the block : $$F_2=W+F_1$$ To avoid complications I assume that the block is cuboid so that the areas of upper and lower faces are equal.
Suppose the air pressure is constant throughout the upper part of the container. Then an increase in air pressure increases the forces $F_1, F_2$ equally, so the depth at which the block floats in the water does not change. The increase in pressure at the upper face is transmitted through the air and water to the lower face, increasing it by the same amount.
The air pressure would be approximately constant throughout its volume if the air is only slightly compressible and its density is low compared with that of the water. Both these conditions usually apply at typical atmospheric pressures.
However, if there is a significant pressure gradient in the air then the pressure at the surface of the water will be greater than at the upper face of the block. It is the pressure at the water surface which is transmitted to the lower face of the block, so the increase in force on the lower face would be greater than that on the upper face, and the block would rise up in the water.
Another way of seeing this is to imagine that the air becomes as dense as the water. Then since the block floats in water it will also float upwards into the dense air.
The following is multiple choice question (with options) to answer.
Because it's less dense, water floats on top of | [
"honey",
"vegetable oil",
"our insect overlords",
"water"
] | A | denser liquids settle below liquids that are less dense |
OpenBookQA | OpenBookQA-1324 | zoology, entomology, ethology, ant
Title: What happens to an ant colony when the queen dies? Does the colony collapse? Do workers keep following the last orders? Or can future queens replace the dead one? I'm guessing this might also depend on each specific sub-species. Not really my field, but I can point to this review which discusses a couple of different ways in which ants organize their communities:
Heinze. 2008. The demise of the standard ant (Hymenoptera: Formicidae)
I know that in some species there can be several queens per colony (so more robust to queen deaths). In many species, workers can start laying eggs if the queen dies, but these will develop as males (since they are unfertilized). However, in some species (e.g. Platythyrea punctata) the workers can reproduce by parthenogenesis which can stabilize the colony to some extent after the queen dies.
The following is multiple choice question (with options) to answer.
If an organism dies what happens to that organisms population? | [
"relaxes",
"cries",
"increases",
"subsides"
] | D | if an organism dies then the population of that organism will decrease |
OpenBookQA | OpenBookQA-1325 | optics, visible-light, reflection, refraction, lenses
Title: Why can't rainbows form at the start of a storm? I was recently at a park looking at the gorgeous scenery. I looked above and saw thick grey clouds covering up 3/4 of the sky. The sun's light is still visible for 1/4 of the sky, and it looks low enough to refract it's light through the clouds to form a rainbow. The rain started dripping slowly for 10 minutes. At five minutes I decided to take a panorama shot and ask the question, why won't a rainbow form at the start of a storm. I thought the place I was standing had the perfect condition for a rainbow to form.
Here is the panorama scene shot
There were a few rain drops pouring from the sky
The time I looked at the sky was 5:00 p.m., so the sun should be at an appropriate location.
But even if my scenario didn't give a rainbow, is this rare event still possible? The big deal with a rainbow is the angle between the sun and water droplets. The sun has to be behind you and the rainbow will occur at about 42 degrees away from the line from the sun through you. If everything lines up, you can have a rainbow at any time. (I've seen them on water spraying from a hose where things lined up just right.) This will work better when the sun in low in the sky, if the sun is too high in the sky the line from it to you goes into the ground. Since thunderstorms are often afternoon phenomenon, the sun is more likely to be low in the sky after the storm than before.
Looking at your panorama, it doesn't look like the sun was visible to you, so I wouldn't expect to see one.
The following is multiple choice question (with options) to answer.
On a morning when the weather is clear, the sky is | [
"bright",
"cloudy",
"stormy",
"dark"
] | A | clear weather means sunny weather |
OpenBookQA | OpenBookQA-1326 | virology, epidemiology, coronavirus, bats
Title: Why are bats the source of dangerous coronavirus pandemics? Why do coronaviruses come from bats?
I mean, why precisely coronaviruses and not (for instance) herpesviruses?
It looks like bats host more zoonotic viruses (per species) than rodents, although they don't develop any sign of disease.
The article above says that rodents host more zoonotic viruses than bats overall (68 against 61), but at the same time most of the latest pandemics originated from bats.
It also seems that bats could be involved in the maintenance of ebola viruses.
My question is: why did these major pandemics originate from bats and not from rodents, although rodents host more zoonotic viruses overall?
We should also take into consideration that human-rodent interaction is usually more likely than human-bat interaction, except for people who consume bats (like Chinese people; this would (partially) explain why both SARS and 2019-nCoV developed in China).
The preponderance of links between bat and human pathogens has led to a debate about whether bats disproportionately contribute to emerging viral infections crossing the species barrier into humans (26–30). Given the diversity of the Chiroptera order (Figure (Figure1),1), we may simply see more bat viruses because there are so many (>1,300) species of bats (31). However, even when accounting for the fact that they make up ~20% of extant terrestrial mammals, bats are overrepresented as reservoir hosts of pathogens with a high potential for spilling into human populations (32, 33). In fact, no known predictors that have been described to impact the likelihood of crossing the species barrier, including reservoir host ecology, phylogenetic relatedness to humans or frequency of reservoir-human contact, explain this pattern (32). Thus, why bats are such a frequent source of pathogenic human viruses remains a tantalizing mystery.
--Going to Bat(s) for Studies of Disease Tolerance
Other references that debate whether bats are special, generally conclude that they might somehow be, and argue about causes, include
The following is multiple choice question (with options) to answer.
Imagine a huge rabies epidemic, where all the cats in the world died, which species would over run the earth? | [
"Rodents",
"Pachyderms",
"Butterflys",
"Homo sapiens"
] | A | as population of predators decreases , the population of prey will increase in an environment |
OpenBookQA | OpenBookQA-1327 | It is easy to see from this website, problem/solution 23, http://books.google.com.au/books?id=8NtJLfGf94QC&pg=PA431&lpg=PA431&dq=monkey+climbing+ladder+on+pulley&source=bl&ots=2tWFRhdKME&sig=9ocddC7lk53A1_XdrVAwPm7MBw0&hl=en&sa=X&ei=Jv9SUevUEoTziAfSs4HIBg&ved=0CDAQ6AEwAA#v=onepage&q=monkey%20climbing%20ladder%20on%20pulley&f=false, that as the man moves up a distance $l'$, the centre of gravity moves up by a distance $l = \frac{ml'}{2M}$. Where $m$ is the mass of the man, and $M$ is the mass of the counter-weight.
This means that if the man is moving at a velocity of $V$ meters per second, then the centre of gravity will move up at a rate of $\frac{mV}{2M}$ meters per second as well.
I finally think something works. I don't need to imagine anything either. So, I assume the block's lower part is at height $H$ from the ground, ladder's last step at height $h$, the height of ladder being $l$ and the distance of man from the bottom being $x$ (where $x<l$ ).
The following is multiple choice question (with options) to answer.
A cat finds it easiest to get a grip when climbing up | [
"plastic pole",
"carpeted pole",
"icy pole",
"metal pole"
] | B | as roughness of a surface increases , friction will increase |
OpenBookQA | OpenBookQA-1328 | astronomy, everyday-life, popular-science, climate-science
It is for much the same reason that Winter is colder than Autumn, even though they have the same amount of daylight hours.
The following is multiple choice question (with options) to answer.
Miles above the equator, people from several faiths celebrate holidays in | [
"cool months",
"eastern months",
"more months",
"warm months"
] | A | December is during the winter in the northern hemisphere |
OpenBookQA | OpenBookQA-1329 | homework-and-exercises, newtonian-mechanics, forces, energy, work
Title: A man carries an object in two different ways. In which will work done be greater? The man is carrying a mass of 15 kg over a distance of 2 meters. I think that in case(i) the work done would be greater as both the force applied and displacement are in same direction. But the answer says case(ii). How will that be possible. Please clarify. Rather than thinking of the force applied by the man and the distance moved by the block, think of the energy difference.
You will notice that in the first case, the body is just shifted parallel to the horizontal surface i.e. its P.E does not increase. But in the second case, the potential energy increases, which invariably means that he has done work.
Now coming to your doubt, in the first case, the man exerts a force in the upward direction (to hold the weight) while displacement is perpendicular.
In the second case, the man exerts a force on the rope, and rope transfers the force to the block, in its direction of motion (upwards).
Hope you understand
The following is multiple choice question (with options) to answer.
A person needs to move a boulder from a crevice to a bluff. The person employs the use of | [
"a fast car and a ball",
"a plank with one end raised",
"a small bowl of soup",
"a stick with a leaf"
] | B | an inclined plane is used for raising objects |
OpenBookQA | OpenBookQA-1330 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
The earth has continents that experience different things at different times, depending on where on Earth's axis it is, such as | [
"cartoons",
"forests",
"lunch",
"Christmas"
] | D | the Earth rotates on its axis on its axis |
OpenBookQA | OpenBookQA-1331 | 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.
A mole can avoid being detected by hawks, owls and other predators by | [
"moving slowly",
"setting traps",
"traveling beneath soil",
"building decoys"
] | C | living underground can be used for hiding from predators |
OpenBookQA | OpenBookQA-1332 | meteorology, climate-change, gas, pollution
Title: Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?
Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?
Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then. As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds). The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years). You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm. As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective. For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly. Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic). Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
The following is multiple choice question (with options) to answer.
Factories often add something to the environment that is | [
"helpful",
"productive",
"sanitizing",
"posionous"
] | D | polluting means something poisonous is added to an environment causing harm to the environment |
OpenBookQA | OpenBookQA-1333 | thermodynamics, everyday-life, cooling, humidity
This is actually a very good question. There appears to be two competing factors involved. Evaporative cooling due to transpiration from the trees cools the air, increasing heat transfer away from the skin making it feel "cooler". But at the same time you would think transpiration increases the humidity in the air, potentially interfering with evaporative cooling of skin perspiration, making you feel "warmer"
The fact that you experienced "cool" rather than "warm" suggests to me that the relative humidity (RH) of the air was low at the time, so that it was capable of absorbing the moisture and cooling the air without significantly raising the RH under the tree to interfere with evaporation of skin perspiration, thus making you feel "cool".
If the RH was high, particularly at or near saturation (100%), transpiration evaporation from the tree, and its cooling effect, ceases. Likewise, evaporative cooling of perspiration ceases, both of which would make you feel "warm". For more information on transpiration of plant, see: https://www.polygongroup.com/en-US/blog/how-humidity-affects-the-growth-of-plants/
Bottom line: The higher the RH the warmer you will feel, whether you are under a tree or not.
Hope this helps.
The following is multiple choice question (with options) to answer.
As the amount of water a plant receives increases what will usually happen with it? | [
"diminish",
"shrinking",
"grow metal",
"expanded proportions"
] | D | as the amount of water received by a plant increases , that plant will usually grow |
OpenBookQA | OpenBookQA-1334 | waves, acoustics, absorption
1.3. Insulation
Not much to say here. This is a very complex topic combining impedance mismatch to reduce transmission of airborne sound as well as vibrations to tackle the issue of structure-borne sound and vibrating structures which re-radiate sound.
The main idea here is to provide as much mass as possible to make heavy constructions that are very hard to move/vibrate. Since this is not always possible one could use the reflection principles described above to direct sound energy away from the adjacent rooms while at the same time trying to convert as much energy as possible to thermal. The result usually is "sandwich" multi-layer setups that induce reflections at each layer interface (see the last image above) with some of the layers being absorptive to allow for conversion losses. Combining this strategy with as much vibration isolation (rubber and springs are the norm here) as possible good results can be achieved.
2. Putting it all together
Now we do have enough knowledge to describe what is going on when you place an absorptive panel, either close to or on the wall.
Sound reaches the panel and since the impedance of the panel is neither $0$ nor infinite - $\infty$ - part of the incident energy is reflected with some phase shift. The rest of the energy denoted $E_{t}$ and equal $1 - E_{r}$ propagates into the panel. Part of this energy is converted to thermal energy and the rest reaches the interface of the panel and the next material. Let's assume that this is the wall and we have a case similar to that of the last picture above. Part of the remaining energy will be reflected into the panel due to the impedance mismatch between the panel and the wall and the rest will go into the wall (in there some of it may reflect at this interface and be re-radiated into the room but we'll assume this won't happen for simplicity).
Now, the portion of the energy reflected into the panel will go through some additional losses (conversion to thermal energy) and will reach the first interface between the panel and air but from the side of the panel this time. The same process will take place with a part of the energy being re-radiated into the room and part of it going back into the panel. This is depicted in the image mentioned before except for the transmission through the wall (it is assumed completely reflective).
The following is multiple choice question (with options) to answer.
The diaphragms in the microphone and speaker convert sound energy into | [
"light energy",
"low voltage electricity",
"back message",
"heat energy"
] | B | telephones convert sound energy into electrical energy |
OpenBookQA | OpenBookQA-1335 | the-moon, moon-phases
Title: Red cresent moon Yesterday night i witnessed something very strange when i looked outside the window. I saw the moon (crescent) but it was dull red and right on the horizon ,which is strange considering that it is usually on the upper right of the night sky and white in colour. On further inspection with my binoculars i noticed it was lowering down until it was hidden by the mountain range (5km away) next to my building, this all occurred within a few minutes (about 5).
Tonight i saw the moon (crescent) had again returned to its normal position.
Please explain the cause for this, i'm completely baffled!
(Sorry for the poor wording, i'm not familiar with all the astronomical terms!) The dull red color has been due to atmospheric causes, like the reddish sun close to sunset. There hasn't been an astronomical reason for the reddish color.
A few days after New Moon moonset occurs short after sunset, so you won't see the Moon high over the horizon at those evenings. With each day the Moon is a little higher above the horizon after sunset. It's hence less close to the horizon at the same time of the day. Less close to the horizon means less atomospheric absorption/scattering responsible for the dull red color, assuming the same weather conditions.
At Full Moon the Moon is at the opposite side of the Sun relative to Earth. Moon is then rising shortly after sunset.
The following is multiple choice question (with options) to answer.
The moon looks different in different parts of | [
"April",
"today",
"this week",
"2018"
] | A | the phases of the Moon change the appearance of the Moon |
OpenBookQA | OpenBookQA-1336 | geophysics, plate-tectonics, earth-history, continent
Title: Why Do Supercontinents Form? It would seem, on the face of it, improbable that the continental land-masses would accumulate into a single composite, yet it has happened numerous times, and is expected to again in the future.
There must likely then be some aspect of plate tectonics which favors these arrangements.
Can anyone provide an explanation?
EDIT: This is not, as I see it, a duplicate of the 'What are the causes of the supercontinent cycle?' question. This question goes to what process drives the formation of any & all supercontinent formations, which I assert should be improbable, made more improbable by their recurrence, not so much the cycle itself. The other question did not address this more fundamental aspect, or in any case receive a pertinent account of its resolution. If anyone wants to engage on this, or doesn't see the distinction, please do so in the comments or a chat. I think the mechanisms that you're looking for are subduction, paired with the "stickiness" of continental crust.
The subduction of oceanic crust under continental crust inevitably creates a net movement of crustal material toward a continental plate. Any oceanic plate that is carrying continental material will therefore always drag that continent toward the continental plate that it is subducting underneath, always resulting in eventual collision.
If an oceanic plate has subduction occurring on both sides, the ocean will inevitably narrow until it closes, thereby causing the continental plates on either side to collide.
In every case, subduction inevitably pulls continents together.
Furthermore, once continental plates collide, they have a tendency to stick together for long periods of time, increasing the likelihood that all continental material will eventually accumulate there.
The following is multiple choice question (with options) to answer.
If the earth were small enough to put on a plate and serve up for dinner, the being eating it would get mouthfuls of | [
"stew",
"towels",
"stone",
"corn"
] | C | Earth 's surface is made of rock |
OpenBookQA | OpenBookQA-1337 | evolution, botany, ecology, plant-physiology, plant-anatomy
Title: Why do some plant species have lobed leaves, while similar species in the same habitat don't? Some plants have lobed leaves, like the English oak (Quercus robur), while other plants growing the same deciduous woodland habitats, and very often growing alongside oaks, such as the European beech (Fagus sylvaticus) don't have lobes. Here are two two leaves side by side for comparison:
These two species should be subject to most of the same evolutionary pressures. Why would one evolve lobed leaves, whilst the other has only tiny serrations? This is a question for which, I think at the moment, we don't have a clear answer.
It is important to bear in mind that the leaf plays a number of important roles in the plant (photosynthesis, thermoregulation etc.) so leaf shapes probably evolved through a process of successive trade-offs. This may make it difficult to identify the exact selection processes operating on any one species. In contrast, something like the eye has a well-defined single function, which in principle at least, makes it easier to understand the link between form and function.
From Niklas (1988):
Life history and optimisation theory suggest that the number of
phenotypic solutions that allow for different equally successful trait
combinations increases as the number of trade-offs increases – a
conclusion that applies to traits within the leaf (e.g. for shape) as
well as to leaf–branch relationships.
However, there are a number of ideas to explain leaf shape diversity which include:
Thermoregulation
It has been shown that by adding lobes to leaves, the rate of heat transfer across a leaf is greater than that of an unlobed leaf of the same area (e.g. Gurevitch and Schuepp 1990). So, lobed leaves may be selected for under certain environmental conditions.
hydromechanical constraints
Lobed leaves may have greater hydraulic efficiency. For smaller veins, hydraulic pressure increases as they present an increased resistance to water flow. This places stress on the deliate outer leaf tissues. If lobed leaves have relatively less mesophyll tissue than large, highly conductive veins, they may have reduced hydraulic resistance compared unlobed leaves (Sack and Tyree 2005).
The following is multiple choice question (with options) to answer.
transpiration happens in the leaves of what? | [
"rocks",
"shrubbery",
"cars",
"animals"
] | B | transpiration usually happens in the leaves of a plant |
OpenBookQA | OpenBookQA-1338 | ### Exercise 20
Mr. Halsey has a choice of three investments: Investment A, Investment B, and Investment C. If the economy booms, then Investment A yields 14% return, Investment B returns 8%, and Investment C 11%. If the economy grows moderately, then Investment A yields 12% return, Investment B returns 11%, and Investment C 11%. If the economy experiences a recession, then Investment A yields a 6% return, Investment B returns 9%, and Investment C 10%.
1. Write a payoff matrix for Mr. Halsey.
2. What would you advise him?
#### Solution
1. .14.08.11.12.11.11.06.09.10.14.08.11.12.11.11.06.09.10 size 12{ left [ matrix { "." "14" {} # "." "08" {} # "." "11" {} ## "." "12" {} # "." "11" {} # "." "11" {} ## "." "06" {} # "." "09" {} # "." "10"{} } right ]} {}
2. 010010 size 12{ left [ matrix { 0 {} # 1 {} # 0{} } right ]} {}, 010010 size 12{ left [ matrix { 0 {} ## 1 {} ## 0 } right ]} {} or 010010 size 12{ left [ matrix { 0 {} # 1 {} # 0{} } right ]} {}, 001001 size 12{ left [ matrix { 0 {} ## 0 {} ## 1 } right ]} {}, value=.11value=.11 size 12{"value"= "." "11"} {}
### Exercise 21
Mr. Thaggert is trying to decide whether to invest in stocks or in CD's(Certificate of deposit). If he invests in stocks and the interest rates go up, his stock investments go down by 2%, but he gains 1% in his CD's. On the other hand if the interest rates go down, he gains 3% in his stock investments, but he loses 1% in his CD's.
The following is multiple choice question (with options) to answer.
A person wants to show that they have lost money with their business, and they want to show someone. They decide to use a graph that shows | [
"more money",
"circled things",
"pictures of cats",
"ups and downs"
] | D | a line graph is used for showing change over time |
OpenBookQA | OpenBookQA-1339 | newtonian-mechanics, fluid-dynamics, acceleration, simulations, power
For your fan, air far away is still. It accelerates as it is sucked in, and slows down as it blows away. When it is far enough away, it is going so slowly that it might as well be still.
The amount of air passing through a fan in a given time is proportional to $v$, the velocity of the air. Said another way, the time it takes a given amount of air to pass through is inversely proportion to $v$.
The kinetic energy of the moving air is $E = 1/2mv^2$. Obviously, air moves at different speeds in different places. But suppose you double the air speed. The air in the fan will double its speed. As the air leaves the fan, it spreads out. But at each place, it is approximately true that it will go twice as fast as it did before. You can reasonably expect that if you double the speed through the fan, that all the moving air will double its speed, at least to some level of approximation.
This tells us something important. We can either take some sort of average $v$, or we can consider the energy of each piece of moving air. Either way, we find that
$$Power = \frac{Energy}{Time} \propto \frac{v^2}{1/v} = v^3 $$
So to double the air speed, the fan needs 8 times the power. $Power \propto v^3$ will be the most important part of your simulation.
The following is multiple choice question (with options) to answer.
A fan pushes air with | [
"forks",
"straw",
"rotating flat surface",
"lumber"
] | C | the vanes rotating in an electric fan causes air to move |
OpenBookQA | OpenBookQA-1340 | organic-chemistry, alcohols, organophosphorus-compounds
Animal studies are consistent in reporting a decrease in the body weight of rats receiving ethanol solutions as the only source of liquids. Concentrations of ethanol as low as 5% (v/v), which are similar to the ethanol content of a Brazilian beer, or as high as 40% (v/v), solution similar to spirit drinks, are related to decreased body weight gain (9). Similar results have been reported for 20% (v/v) ethanol solution (10).
Different results have been obtained for malnourished animals. Da-Silva et al. (11), studying rats which had been treated with ethanol for 90 days, reported a significant weight gain by malnourished rats (50% food restriction) drinking a 20% (v/v) ethanol solution when compared to malnourished rats drinking water. A more recent study (12) reported improvement in somatic and motor development and a decrease in the mortality rate of the offspring of malnourished rats drinking low doses of ethanol (5%, v/v). These data suggest that malnourished rats can benefit from ethanol calories.
In summary, in spite of the large number of studies on the effects of ethanol in well-nourished animals and humans, there is still controversy about how well ethanol-derived calories can be utilized. Fewer studies are available about special physiological conditions such as malnutrition. Over the last few years, scientific research has mainly focused on obesity, an increasing problem in developed countries, which led us to the false belief that malnutrition was no longer a problem worth investigating. However, there are still 800 million malnourished people in the world (13). The decreasing interest of the scientific community in problems related to malnutrition has left many questions without an answer. Ethanol consumption and its consequences on the malnourished organism are among them.
In view of the importance of malnutrition in Brazil - 22% of the population or 40 million people are malnourished (14), as well as ethanol consumption and alcoholism - 11% of Brazilian population are alcoholics (15), the aim of the present study was to assess the use of ethanol calories in a dose/effect model by evaluating body weight before and after the installation of malnutrition.
The following is multiple choice question (with options) to answer.
People eating meals or snacks containing substances are further processed in the | [
"reproductive system",
"burgers and fries",
"gastro tract",
"ocular department"
] | C | the breaking down of food into simple substances occurs in the digestive system |
OpenBookQA | OpenBookQA-1341 | star, planet, telescope, light, space
Title: How do I know what I'll be able to see? So I live in a suburb in Victoria, Australia. Less than an hour away from the city and I guess there is a bit of light pollution because from my backyard I can probably only see about 15 - 20 stars (probably less), I'm wondering what these stars are, and what I'll see when I get this telescope:
https://www.opticscentral.com.au/saxon-707az2-refractor-telescope.html?___SID=U#.WXQNMtN940r
This is going to sound stupid but how do I know when there are planets in the sky that I can see? I don't think I've ever actually seen a planet other than the moon.
Thank you. Firstly, if you're planet spotting, don't worry too much about light pollution. The planets are some of the brightest objects in the sky and some (especially Jupiter) can easily be observed even with a full Moon - the full Moon (along with the Sun!) is the biggest contributor to light pollution!
Take a look at the list of brightest stars ( https://en.wikipedia.org/wiki/List_of_brightest_stars ), which also contains estimates for the brightness of the Sun, Moon and major planets. There aren't typically any stars brighter from Earth than Venus, Jupiter, Mars and Mercury and precious few brighter than Saturn. I'm going to suggest you probably have seen many of the planets - but just didn't recognise them.
+1 for Stellarium ( http://www.stellarium.org/en_GB/ ). It's free, intuitive and very visual to use. You can put in your local viewing location and it gives you a view for any time of the night, future or past. At the time of writing (23 July 2017), Saturn and Jupiter should be looking good for the Southern Hemisphere. This rotates throughout the year, and Stellarium will help with this.
Do a web search for "the sky at night in the southern hemisphere" and you'll find a number of examples of websites with highlights to look for when you get out.
Couple of final suggestions:
The following is multiple choice question (with options) to answer.
If you're in the North Pole the North Star may be visible when? | [
"a weed",
"two months",
"a day",
"all year round"
] | D | the Earth revolving around the sun causes stars to appear in different areas in the sky at different times of year |
OpenBookQA | OpenBookQA-1342 | photosynthesis, botany
Title: Photosynthesis - Light Intensity Say I was conducting an experiment for photosynthesis. If I moved light closer to the plant, what effect would this have on the process of photosynthesis? The rate of photosynthesis varies from plant to plant. Some plants require more light and some require less. If you move light closer to the plant, in most scenarios the rate of photosynthesis is likely to be increased. For some plants a minimal light is enough for their photosynthesis, so for those plants, moving light source closer or further will have less effect.
The following is multiple choice question (with options) to answer.
How does darkness impact photosynthesis? | [
"positively",
"increases absorption",
"very poorly",
"increases endurance"
] | C | darkness has a negative impact on photosynthesis |
OpenBookQA | OpenBookQA-1343 | human-biology, reproduction
Title: Why are animal births not taken as seriously as human births? When humans give birth, more than often medical assistance is needed. Others gather around and frantically look for any way to help. But when an animal gives birth, it is usually seen as a moment where you give the female its space and let the birth occur naturally and without any assistance. The animal is of course in serious pain just as a female human but this is more than often not taken into account. Why is it that animal births are not taken as seriously? Our heads are bigger.
There's some debate on the issue, but in essence, human brains, and therefore heads, are very large relative to our body size. This is handy for all the intelligent things we like to do, but can be rather painful during birth. Because we walk upright, the size of a newborn's head is actually a non-trivial fact during the birthing process. There are two major implications.
The first is that human birth hurts. You can watch the birth of other animals and they seem to brush it off, but for humans, forcing that huge head through a relatively small birth canal is difficult. Evolution has (supposedly) limited the size of the hips because, while that would allow an easier birthing process, it would negatively impact our ability to walk. As such, it has to hurt.
Secondly, in order to make the process easier, humans rotate during birth. The end result is that, unlike even other closely related primates, humans come out backward in a way that is very difficult for a birthing female to attend to. This almost requires having another person or two on hand to help out. This would, of course, be a huge reinforcement for social connections.
A few books I know of touch on this. Up From Dragons deals with the brain size/hip size issue and The Invisible Sex talks about rotation during the birthing process and the social implications.
The following is multiple choice question (with options) to answer.
Birds give birth to their babies while still in an egg. Mammals, however, give birth to their babies | [
"scrambled",
"already alive",
"dead",
"Old"
] | B | mammals give birth to live young |
OpenBookQA | OpenBookQA-1344 | evolution, life-history
Title: Has there been any observation of species adapting the evolution process? I am very interested in the evolution of the evolution process itself. There are of course a lot of things that influence how evolution will work, but for this question, I am interested in things that are only related to the evolution process. Examples could be increase chance of mutations in newborns, change in reproduction age, and similar. I am specifically interested in observation where the evolution process itself has adapted to a change in the environment. Bacteria such as E. coli are known to increase their mutation rate (by switching to a more error prone polymerase among other things) when under stress. This can mean being placed in a medium where it's not adapted to grow (http://www.micab.umn.edu/courses/8002/Rosenberg.pdf) or when treated with antibiotics (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088971/?tool=pmcentrez).
The following is multiple choice question (with options) to answer.
what affects an organisms acquired characteristics? | [
"the moon",
"gravity",
"its immediate surroundings",
"birthday"
] | C | an organism 's environment affects that organism 's acquired characteristics |
OpenBookQA | OpenBookQA-1345 | visible-light, atmospheric-science, sun
Title: Why is there less UV light on earth in winter? So I have often read that, at least in e.g. northern Europe, in the colder seasons, there is not enough UV (-B) light arriving from the sun, so many people have not enough vitamin-D from that.
At first I thought it was simply due to the sun "shining" for only a much shorter period of time in winter compared to summer and hence less possible exposure (not to mention that most of the skin area is covered then).
But I just had a thought coming to my mind, thinking about that in the mornings and evenings, we mostly see red light here, the higher end of the visible spectrum not getting through.
I am not familiar with the physics behind that phenomenon, but thought that the higher-end of the spectrum like the invisible UV light may not be getting through here for even longer parts of the day towards and away from high noon, and that in winter, the part of the day where UV gets through is maybe very narrow and that's why it's said not to be enough.
Is that correct? And how exactly does this work physically? The reddening of the sun has to do with Rayleigh scattering as the sun passes through more atmosphere. (see picture). This is in a sense, related to less energy but not the primary cause.
The reason we get less solar energy per square meter is that the angle of the sun in the sky affects how spread out the light is. (see updated picture). Ignoring atmospheric effects, it's the sin of the angle times peak energy. 90 degrees or directly overhead, figuring peak solar energy is 1,369 Watts per square meter (that also varies with distance), but the energy from the sun is mostly governed by the sin of the angle.
45 degrees: 1,369 * sin(45) W/m^2 or 71% of overhead or Zenith. 20 degrees above horizon, 1,369 * sin (20), just 34% of peak solar energy. Winter corresponds with the sun being lower in the sky, sunlight is more spread out. There is measurably less energy hitting the same area when the sun is low in the sky.
Passing through more atmosphere amplifies that somewhat, but the angle of the sun is the primary cause.
The following is multiple choice question (with options) to answer.
sunlight produces | [
"darkness",
"wind",
"solar radiation",
"snow"
] | C | sunlight produces heat |
OpenBookQA | OpenBookQA-1346 | agriculture
Title: What does "permanent field" mean in agriculture? I am reading a book that in a paragraph talks about the agricultural methods used in prehistoric Finland.
The further north and east, the more extensive the amount of
burn-beat cultivation, which was a far from primitive form of
agriculture. The yield was many times higher (twenty- to thirty-fold)
than on permanent fields (five- to ten-fold), and there were multiple
varieties of the technique
A history of Finland by Henrik Meinander.
One of them is burn-beating. Like I understand, in burn-beating people cut down the trees in the forests and burn the topsoil. This way they can use that soil for 3 to 6 years for cultivation.
The other method is permanent field. I have searched the internet and the result I got was "permanent crops", like here. In which case people planted trees once in a field and harvested them multiple times.
But in another research about prehistoric Finland it was saying:
The site of Orijärvi shows that permanent field cultivation, with
hulled barley as the main crop was conducted from approximately cal AD 600 onwards.
The following is multiple choice question (with options) to answer.
A field is tilled and soil is filled with nutrients after years of | [
"bears eroding trees",
"the flu dissolving",
"stones being destroyed",
"corn burning up"
] | C | soil is formed by rocks eroding |
OpenBookQA | OpenBookQA-1347 | photosynthesis, respiration, ecosystem, decomposition
Maybe you should study the metabolic processes of plants and life in general to better understand this. All life consists of chemical reactions that build up structures; in order to build them up you need energy (because of the second law of thermodynamics), and all living things create that energy by breaking down complex molecules into simpler ones. (as such it would be more accurate to say that all life consists of chemical reactions that build up and break down various structures). You might be wondering "but what about the difference between autotrophs and heterotrophs I heard about"; the difference between those is where they get the complex molecules from in the first place. Autotrophs use a different source of energy to build them up while heterotrophs get them from their environment. As such, you can think of every living thing as being made of two kind of molecules: those that actually form their structure (in humans, the molecules that make up cell membranes, bones, muscles, etc) and those that are stored in order to be broken down to power the whole system (in humans that's fat, glycogen, glucose, etc). Of course a molecule can do both; if you're starving your body may start to break down structural molecules for power. There are many different ways of breaking down those big molecules for power; the most efficient one, that starts with a big chain of carbon atoms and cuts it down into individual CO2 molecules using O2 molecules, is called aerobic respiration (i.e. respiration that uses oxygen).
Because those complex molecules are required to power all life, autotrophs (the organisms that actually make them) are very important, and the processes they use to make them are very important too. The process that makes almost all of the molecules that power almost all life on earth is photosynthesis, which uses the energy from the sun to power a reaction that converts CO2 from the atmosphere into big carbon-based molecules we'll call carbohydrates. This is called "fixing carbon", since the carbon atom is the most important one; measuring how much photosynthesis is happening is another way of measuring how many carbon atoms move from being part of a CO2 molecule to being part of a plant.
The following is multiple choice question (with options) to answer.
Every single bit of growth and life on earth is connected to the power of | [
"solar aliens",
"magic orbs",
"magic beans",
"daylight"
] | D | the sun is the source of energy for physical cycles on Earth |
OpenBookQA | OpenBookQA-1348 | cell-signaling, chemical-communication
Title: How many molecules are generally required for cell signallng processes for given cases? I know its really a broad topic but I am interested in just few cases:
Quorum sensing
neurotransmitters for the communication of images/ general information
hormones/pheromones
I actually want to know that does a single or hundreds of molecules are needed to communicate information from one cell to another.
I searched but approx number of molecules, I can't find anywhere. A cell can interact with other cells in zillions of ways. You can send information from one cell to other cells via neurotransmitters, hormones, pheromones, electric signals, magnetic resonance ,leukotrines etc.
In general a single type of molecule is enough to send such information. Like you require only Acetylcholine(Ach) as neurotransmitter to transmit various nerve impulses.
But, even for a single type, you require thousands of molecules. Like 1 molecule of Ach can do almost nothing and would immediately be broken by Acetylcholinesterase. You require 1000s of such molecules.
You can modify the communicating information via different types of transmitters. You can use GABA or glycine to supress any information exchange or use dopamine to enhance it. But again you will need many molecules of GABA or Glycine.
For visual pathway, you can use no. of types of transmitters like glutamate, glycine, gaba, dopamine, acetylcholine, substance P etc.
Neurotransmitters for visual pathway.
Hormones are transmitters that are required in small quantities. But, again you require certain concentration. There is normal blood concentration of various hormones like 80 pg/ml for calcitonin.
Quorum sensing use transmitters like AHLs. Again a certain threshold value is required for them to act.
Again, to produce these transmitters you have to go through a rigorous process of transcription, translation and post-translational modifications.
So, for cell to communicate a rigorous process is used.
The following is multiple choice question (with options) to answer.
A lady needs to be able to confirm what very small text reads on her pill bottle, so a ______ is necessary. | [
"microscope",
"telescope",
"magnifier",
"binoculars"
] | C | magnifying glass is used to see small things by making objects appear bigger |
OpenBookQA | OpenBookQA-1349 | optics, geometric-optics, telescopes
For demonstration purposes the spectral lines formed on a screen and measuring the wavelength of the light approximately is useful but for reasonable accurate and simple measurements of wavelength the telescope wins out.
The following is multiple choice question (with options) to answer.
A telescope is used to observe what? | [
"heavenly bodies",
"star charts",
"animals",
"water"
] | A | a telescope is used for observing stars |
OpenBookQA | OpenBookQA-1350 | electrical, fire, polyethylene
My hypothesis is that the static buildup is being caused by friction of the foam with the surrounding air, at a rate that is faster than its ability to release it through the shaft (its only contact with ground).
Questions:
Shall I discard the idea that the static buildup is being caused by friction between layers of the foam in the roll (as they're the same material, theoretically they're not apart in the triboelectric series)?
Other than spraying the area (or even the foam) with any watery solution to increase the conductivity of the air, what would you suggest to keep the sparks from jolting and causing fires?
2A. If a watery solution spray is the best solution there is, what makes a good mixture?
2B. Would a metallic side plate in contact with the shaft and the side of the roll be a good, safe solution? If so, what material would you use?
How could I measure the static electricity built up into the roll to ascertain a "safe limit"? Since asking the question I went to study the subject a little bit more. I want to share my conclusions, hoping that they could be of help to someone else.
Static buildup can't be caused by friction (or contact) between layers of the same material. They don't make a triboelectric pair. Most likely, the static is being generated by the foam slipping in the surrounding air.
This brings us to the second point: try to humidify the air. That could be accomplished by spraying the area, but more technically by installing humidifiers.
In addition to installing the side plate you mentioned (a good conductor, such as copper is the obvious pick, as it doesn't require any mechanical properties), it's a good idea to ensure that the chassis of the rolling machine is properly grounded (as well as those structures in which the material slips).
The following is multiple choice question (with options) to answer.
Deposition is caused by what? | [
"venus wind",
"forceful gales",
"airplanes",
"eroding mentalities"
] | B | erosion causes deposition |
OpenBookQA | OpenBookQA-1351 | star, galaxy
If you're on a farm, away from cities, in a place with reasonably low light pollution, and your eyes are good, and you've been sitting in perfect pitch black darkness for at least 30 minutes prior - when you look up you can reasonably expect to see a few thousand objects, mostly stars. Keep looking, and after a while you will distinguish one or two thousand more stars, very faint, that you could not see at first sight. Practice this steadily for a few years, and you'll add maybe another thousand; but you won't be able to see those all at once - only one at a time.
Now travel to the Cerro Tololo site in Chile, up in the mountaineous desert, zero light pollution, excellent transparency, and you'll multiply all those numbers by a factor of 2x ... 5x.
As you can see, the numbers are very flexible because there are so many factors involved. You can't just slap a 44k label on it and call it a day; that doesn't make any sense in reality. Astronomers know that the pure magnitude number doesn't mean much by itself, because it is just one factor among many.
In a place with very high light pollution (like where I live, in the middle of a large, dense, sprawling urban area in California), you'd be lucky if you can see a hundred stars at night.
Or, in a place with zero light pollution, shine a flashlight into someone's face, and you've temporarily blinded them. You've reduced the number of stars they could see by an order of magnitude for the next half hour (night vision gradually recovers, and it takes 30 minutes to fully recover, according to US military manuals and visual astronomers practice).
The following is multiple choice question (with options) to answer.
A quiet desert town will see more _____ than a big city will. | [
"buildings",
"cars",
"people",
"stars"
] | D | as light pollution increases , seeing the stars will be harder |
OpenBookQA | OpenBookQA-1352 | biochemistry, ecology, marine-biology, climate-change
So... raising temps can cause less mixing of water due to more stratification (layering), which results in less water in the ocean available to absorb and hold the CO2. This means that as atmospheric CO2 continues to increase, the non-mixing surface layer of ocean water (which will become saturated with CO2 at some point) won't be able to keep up with more and more and more CO2 in the air. As a result, the ocean will decline (and eventually potentially fail) in its ability to "buffer" the ever increasing CO2 in the air. This would mean that the rate of CO2 in the air will start increasing more rapidly (since less and less of it is being absorbed by the oceans).
As for the phytoplankton (which are in this top layer of water), this stratification will not directly result in less CO2 availability to them. As atmospheric CO2 increases, so will the amount in this top layer of water. The rate of increase in CO2 concentration will just slow until a saturation point is reached, but absolute levels will not decline.
Though, note, however, that phytoplankton tend to thrive in areas of high nutrients (i.e., upwelling zones). Less mixing of waters will decrease the upwelling of nutrient-rich, cooler subsurface water. So less mixing (i.e., more stratification) likely would lead to declines in phytoplankton abundance due to decreased nutrients availability. (See here). Perhaps this decreased nutrient availability (which would include loss of carbon sources) is related to what you're referring to?
Read here for some more thoughts: https://earthobservatory.nasa.gov/features/OceanCarbon
Raising Temperatures may decrease CO2 solubility
However, given all this, the solubility of CO2 in water does decline with increasing temperature (see here for raw data). This suggests that some rise in global temps may impact CO2 concentration in ocean waters.
The following is multiple choice question (with options) to answer.
As a body of waters surface area increases what else will increase? | [
"vaporization",
"evaporating milk",
"coals",
"fires"
] | A | as the surface area of a body of water increases , evaporation of that body of water will increase |
OpenBookQA | OpenBookQA-1353 | photosynthesis, cellular-respiration, energy, sugar
Basically, points 4-7 convey that Calvin-Benson cycle not only produces sugar but what it actually does is fix inorganic carbon (as CO2) to organic form (in the form of sugar). So, most (practically all) of the carbon that a photosynthetic plant has, comes from this carbon fixation process and that's how plants are photoautotrophic.
The following is multiple choice question (with options) to answer.
photosynthesis makes food for the plant by converting carbon dioxide, water, and sunlight into what? | [
"dirt",
"sunlight",
"mental energy",
"sugars"
] | D | photosynthesis makes food for the plant by converting carbon dioxide, water, and sunlight into carbohydrates |
OpenBookQA | OpenBookQA-1354 | tissue
Title: What are the main differences between lab-grown tissues and natural tissues from living animals? What are the main differences between lab-grown tissues and natural tissues from living animals?
Using a biologist's classic "structure (anatomy) and function (physiology)" idea, I thought about the followings:
Structure:
It might be difficult to recreate the composition of different tissues / cells in living things precisely with artificial methods. This may lead to bad results when the tissue is used for tests of medicines and cosmetics.
Function:
Cells might not function and produce as expected (or is harder to make them function) in artificial compositions, as cells need strictly regulated environments to function correctly.
The following is multiple choice question (with options) to answer.
All living things are made of parts that contain a | [
"blood vessel",
"heart",
"nucleus",
"skeleton"
] | C | a living thing is made of cells |
OpenBookQA | OpenBookQA-1355 | $SSx = \sum x_i^2 - \dfrac{(\sum x_i)^2}{m} \\ = 17328675.78 - \dfrac{31061.991^2}{61} = 1511507.17534$
$SS_y = \sum y_i^2 - \dfrac{(\sum y_i)^2}{m} \\ = 742779.5112 - \dfrac{6267.028^2}{61} = 98916.56115$
$SS_{xy} = \sum x y - \dfrac{\sum x \sum y}{m} \\ = 3556496.296 - \dfrac{31061.991 \times 6267.028}{61} \\ = 365244.37251$
c)
The correlation between $x$ and $y$ is given by
$r = \dfrac{SSxy}{\sqrt {SSx \cdot SSy}} \\ = \dfrac{365244.37251}{\sqrt {1511507.17534 \cdot 98916.56115 }} \\ = 0.9446$
d)
The results of the calculation of the correlation using Excel is
The correlation is equal to: $r = 0.944591256783634$ the small difference between correlation coefficient $r$ given by Excel and the one found in part c), is due to the rounding errors.
Problem 3
The first four and the last four rows of the stock price of Apple shares and the Nasdaq index from 1980 to 2021 are shown below.(Nasdaq Data from yahoo and Apple share price generated through Excel sheets).
The following is multiple choice question (with options) to answer.
As ipod sale plummet apple reports major | [
"loses",
"raises",
"firings",
"gains"
] | A | as the sale of a product decreases , the amount of money made by the person selling that product will decrease |
OpenBookQA | OpenBookQA-1356 | forces, classical-mechanics, energy
Title: What's the work done in an object to change its direction? Say, for example an object is moving 2m/s right and some force makes it travel 2m/s left. What would be the work done on this object? It starts and ends with the same kinetic energy, but clearly something had to be done to it to make it start moving left. Let's assume the force acting to the left is constant.
For it to change the velocity from 2 m/s to the right to 2 m/s to the left the force must first decelerate the object to 0 m/s. That means the force did negative work on the object because the direction of the force is opposite to the movement of the object while it slows down. Net negative work decreases the kinetic energy of the object.
But since the force remains, it now accelerates the object from 0 m/s to 2 m/s to the left. Now the force is doing positive work since its direction is the same as the motion of the object. Net positive work increases the kinetic energy of the object.
The amount of negative work done by the force to decelerate the object to 0 m/s equals the amount of positive work done by the force to accelerate the object to 2 m/s, for a net work of zero. Per the work energy theorem the net work done on an object equals its change in kinetic energy. Since the net work is zero, the change in kinetic energy is zero.
Hope this helps.
The following is multiple choice question (with options) to answer.
a force acting on an object in the opposite direction that the object is moving can cause that object 's speed to decrease in what motion? | [
"frontward",
"backward",
"downward",
"upward"
] | A | a force acting on an object in the opposite direction that the object is moving can cause that object 's speed to decrease in a forward motion |
OpenBookQA | OpenBookQA-1357 | thermodynamics, statistical-mechanics
Edit 2 I am adding a diagram of the setup. The point is that I start with the setup at 50 °C and 1 atm with water at the bottom and an ideal gas that does not dissolve in water at the top with the two separated by a partition. What will happen when I remove the partition. Will some of the water in liquid phase convert into vapor phase? If so, how does one figure out how much of the water will convert into vapor? Assume we know the mass of the water and that of the gas. As others have said, here's the difference:
Case I: At 50 C and 1 atm, in a system that contains only pure water, all the water will be in a liquid state. That's what phase diagram (a) would show you if the axes were numbered -- you're not on a coexistence line; rather, you're squarely within the liquid region.
Case II: At 50 C and 1 atm, in a system that contains water and air, some of the water will be in the gaseous state.
The natural question is then: Why?
The answer: There's no entropy of mixing in Case I, but there is in Case II.
Specifically: Water molecules will move between phases from regions where their chemical potential is higher, to where it's lower, until the chemical potential is uniform, at which point you've reached equilibrium (with respect to the water).
At 50 C & 1 atm, the chemical potential of pure water in the liquid state is lower than that of pure water in the gas state. Thus, in Case I, where we only have the possibility of pure liquid water and pure gaseous water, all the water will stay in the liquid state.
The following is multiple choice question (with options) to answer.
if liquid is changing its state to gas then that liquid is | [
"slimy",
"cold",
"condensing",
"hot"
] | D | if liquid is boiling then that liquid is hot |
OpenBookQA | OpenBookQA-1358 | Method 2:
Since @Buraian wants equations with the method @Daniel Griscom suggested, here they are: Consider the part of the string that is in contact with the pulley. It experiences a force $$T$$ downwards and $$T$$ towards the left. Say the pulley applies a force of $$N_1$$ on the string ( towards upper right). By Newton's third law, the string applies $$N_1$$ on mass $$M$$ (towards bottom left).
Since $$m_1$$ doesn't swing, the rail (part of mass $$M$$) applies a force $$N_2$$ (towards left) on $$m_1$$ and $$m_1$$ applies a force of $$N_2$$ on $$M$$ towards right. Let $$M$$ (and $$m_1$$)accelerate with $$a^{'}$$, horizontally.
Since the net force on a mass less string is always $$0$$, $$N_1cos(45^0)=T \tag{4}$$ from eq(1),eq(0) and eq(4) we can get the value of $$N_1$$.
Equation of motion for $$M$$: $$N_1cos(45^0)-N_2 = Ma^{'} \tag{5}$$ Equation of motion for $$m_1$$ (X direction ): $$N_2=m_1a^{'}\tag{6}$$
Needless to say, by eq(5) and eq(6) we can obtain all the quantities and predict the motions of blocks. we get $$a^{'}$$ which is the same as $$\ddot{X}=m_1m_2g/((m_1+m_2)(m_1+M))$$ from first method.
Okay the pulley would definitely move, I will set up the laws to be used to show that it will.
The following is multiple choice question (with options) to answer.
A pulley is used to do what with objects? | [
"crush",
"cool",
"increase altitude",
"elevate significance"
] | C | a pulley is used for lifting objects |
OpenBookQA | OpenBookQA-1359 | seismology, earthquakes, seismic-hazards, drilling
Title: Why aren't seismic stations installed very deep underground so as to pre-warn from earthquakes? The velocity of p-waves emanating from earthquakes is in the range of 5-8 km/s (link)--let's assume it is 5 km/s. The earthquake depth is up to hundreds of kms deep underground (link)--let's assume it is 100 km.
That said, if a seismic station is installed at a depth of 50 km, and there are many of them in any given metropolitan area, then we can have a warning that is tens of seconds before the earthquake reaches the surface.
While I realize that drilling down to 50 kn is no easy task, I would have imagined that saving human life is well worth the efforts. Why hasn't this been done so far? Is it that such a short notice (10s of seconds) isn't worth it? The simple answer is that you can't drill to 50 km depth.
The deepest holes ever drilled were to a little more than 12 km, one is named the Kola Superdeep Borehole in Russia, which was a scientific drilling project. The very few others were oil exploration boreholes.
Drilling that deep is extremely expensive and hard. If you go and ask anyone who ever worked on a drill rig, drilling the second 100 metres is always harder than the first 100 metres. And we're talking about kilometres here! There are several problems with drilling that deep. It's extremely hot down there, and the drilling equipment just breaks and stops working. You also need to pump cooling water in and pump out the stuff you're drilling and it gets harder with depth.
This is simply not feasible. Now let's say that you did somehow manage to drill a hole to that depth. How would you put monitoring equipment inside? That equipment has to sustain heat and pressure and still keep working, while being able to transmit whatever it's reading back to the surface. This is not going to happen, not at 50 or 10 km depth.
Another problem is that not all earthquakes are that deep. Some earthquakes originate near the surface, or just several km deep. Having a monitoring station down there isn't going to help. The 2011 Tohoku earthquake (the one that triggered the tsunami at Fukushima) was only 30 km deep. Same thing for the 2004 Indian Ocean earthquake.
The following is multiple choice question (with options) to answer.
A place you would want to avoid that is prone to Earthquakes would be | [
"Kansas",
"Alaska",
"Osaka",
"France"
] | C | earthquakes cause rock layers to fold on top of each other |
OpenBookQA | OpenBookQA-1360 | So our resultant is 30.8 meters, 35.8 degrees north of west. What we can see is that if there is an obstacle in the path here, some big rock that you want to avoid, you can get to the same place by taking a different route which is kind of obvious, but now we just sort of demonstrated that that's true using analytical techniques.
The following is multiple choice question (with options) to answer.
A person using a compass can find their way when they are lost | [
"in time",
"in play",
"in space",
"on water"
] | D | a compass is used to navigate oceans |
OpenBookQA | OpenBookQA-1361 | c#, design-patterns, beginner, classes
//Happiness relates to playing with the pet
public PetMood Mood { get; protected set; }
//Pet hunger level
public HungerLevel Hunger { get; protected set; }
//Has the pet been vaccinated
public bool IsVaccinated { get; private set; }
//The pet class constructor
public void GivePetShot()
{
IsVaccinated = true;
}
public virtual PetMood PlayWithPet()
{
var message = GetPlayWithPetMessage();
if ( (int)this.Mood < 4 )
{
Console.WriteLine( message );
return this.Mood += 1;
}
Console.WriteLine( message );
return this.Mood;
}
public abstract string GetPlayWithPetMessage();
public virtual PetMood PunishPet()
{
string message = GetPunishPetMessage();
if ( (int) this.Mood > 0 )
{
Console.WriteLine( message );
return this.Mood -= 1;
}
Console.WriteLine( message );
return this.Mood;
}
public abstract string GetPunishPetMessage();
public virtual HungerLevel FeedPet()
{
if ( (int)this.Hunger < 3 )
{
Console.WriteLine( GetFeedPetSuccessMessage() );
this.Hunger += 1;
return this.Hunger;
}
Console.WriteLine( GetFeedPetFailedMessage() );
return this.Hunger;
}
public abstract string GetFeedPetSuccessMessage();
public abstract string GetFeedPetFailedMessage();
public HungerLevel StarvePet()
{
string message = GetStarvePetMessage();
if ( (int)this.Hunger > 0 )
{
Console.WriteLine( message );
this.Hunger -= 1;
return this.Hunger;
}
Console.WriteLine( message );
return this.Hunger;
}
public abstract string GetStarvePetMessage();
public void UpdatePet( HungerLevel hunger )
{
if ( hunger != Hunger )
{
Hunger = hunger;
}
}
public void UpdatePet( PetMood mood )
{
if ( mood != Mood )
{
Mood = mood;
}
}
The following is multiple choice question (with options) to answer.
A puppy is sitting in a yard and is at the door, asking to come in. A person looks out the door and sees the pup tremble, so the person can tell that | [
"the dog is lonely",
"the temps have dropped",
"the puppy is happy",
"the pup is strong"
] | B | cool temperatures cause animals to shiver |
OpenBookQA | OpenBookQA-1362 | planet, orbit
Title: Do the orbits of planets change sometimes? Do planets sometimes wobble and get off their paths? What if an asteroid were to hit it? Yes, the orbits change massively over time. For example, Earth's eccentricity (how close to a circle the orbit is), its axial tilt (what causes seasons), and precession (which direction the Earth's spin axis points) change on these huge cycles, tens of thousands to hundreds of thousands of years long. They are caused by the pull of the other planets, mainly Jupiter and Saturn (since they are so huge), as well as the physics of inertial reference frames. These are known as the Milankovitch cycles. Here is a neat video explaining what each of the cycles are in detail. That video is about Earth, but the same concepts apply to all the other planets too, just on different amounts and timescales.
An asteroid hitting a planet would technically change its orbit, however how much is questionable. An asteroid a couple km across would barely nudge the Earth since the Earth is bigger by many orders of magnitude. It would also destroy everything on the planet, but thats another story. Way back in the solar system's formation, when Thea hit Earth (theoretically) it was much closer in size than the Earth, so no doubt that it caused a much more significant shift in orbit.
The following is multiple choice question (with options) to answer.
Earth orbiting what causes seasons to change? | [
"mars",
"saturn",
"local star",
"sunlight"
] | C | Earth orbiting the Sun causes seasons to change |
OpenBookQA | OpenBookQA-1363 | physical-chemistry, inorganic-chemistry, everyday-chemistry, thermodynamics
Title: Strange observation! Every one have observed that when we pour cool water into a transparent glass (or simply glass), some droplets accumulate on the outside part. Did the droplets come pass through the glass? If they didn't, why is there accumulation of water droplets outside the glass? This is happening because of moisture present in air.
When you'll pour the cold water in a glass, the outer surface will also show fall in its temperature.
As you know already know that the heat flows from one body to another body until the temperature of both becomes equal.
So in our case the outer surface of the glass will absorb heat from surrounding, thereby causing in condensation of water present in air as moisture.
Another thing, you might notice that when you take out the bottle of cold water from a refrigerator, it have no droplets present on its outer surface because air inside the refrigerator is dry. But after when you place the same bottle out for a few minutes, you will observe the droplets on the outer surface of bottle.
You can also try to perform your experiment again by pouring normal water (at room temperature) in a glass and then placing it in refrigerator and then take it out after 30-40 minutes. Observe that if there are droplets present on the glass just after you take it out.
See this.
The following is multiple choice question (with options) to answer.
A person puts liquid matter in a glass and it | [
"is hardened",
"evaporates immediately",
"is shaped similarly",
"melts the glass"
] | C | Matter in the liquid phase has variable shape |
OpenBookQA | OpenBookQA-1364 | then
##F=pA = A_Ldgh = 1000 \cdot 9.82 \cdot 12 \cdot \pi (0.20 - 0.003)^2 = 14367.3 N ##
It feels like I should add atmospheric pressure somwhere but I am not 100% sure.
EDIT:
Apparently ## F_{total} = F_{water} + F_{air}##
and the foce from the air is
## F=p_{atm}A_L = 100kPa A_L = 100 \cdot 10^3 \pi (0.20 - 0.003)^2 = 12192.2...##
Thus ##F_{total} = F_{water} + F_{air} = 14367.3 N + 12192.2N =26559.5 N##
Does it look right?
Last edited:
SteamKing
Staff Emeritus
Homework Helper
You have added the force due to air pressure acting on the lid
This problem was translated from Swedish, sorry for any grammatical errors present.
The problem
The grey is liquid is water. The small container is a pipe made of glas and the big container is a barrel. Water is poured into the glas pipe. When water reaches 12m over the barrel top(lid) the barrel breaks.
Calculate
a) the mass of the water in the glass pipe (over the lid)
b) the total force on the lid when the barrel breaks
Relevant equations
Liquid - water
h = 12m
R = 0.20m
r = 0.003m
(^^values from below the figure in my book)
##p=dgh##
The attempt
a)
Density is described by ## d = \frac{m}{V} ##
Volume of a cylinder is ##V = \pi r^2 h##
density for water is ##d = 1000 kg/m^3##
Mass is thus:
## m = d \cdot V = d \cdot \pi r^2 h= 1000 kg/m^3 \cdot \pi (0.003)^2 12 = 0.339292... kg ##
b)
There is a hole in the lid so I calculate the area of the doughnut.
The area of the lid is
The following is multiple choice question (with options) to answer.
A person pours water into a cylinder in order to | [
"touch it",
"observe it",
"taste it",
"make it"
] | B | a graduated cylinder is used to measure volume of an object |
OpenBookQA | OpenBookQA-1365 | bacteriology
Title: Extract bacteria from compost? I'm working on a project where I need to find certain cellulolytic bacteria. I was looking at this list : http://webcache.googleusercontent.com/search?q=cache:CrtQ9T6K7m8J:www.wzw.tum.de/mbiotec/cellmo.htm+&cd=1&hl=nl&ct=clnk&gl=be
How could I selectively separate one of the bacteria types that I had in mind from that list?
So how would I have to extract the bacteria from the compost? A first (and obvious) approach is the use of cellulose agar in order to isolate all the celluloltic bacteria in the sample. Be careful, however, since the nutrient requirements of some of those microbes may be higher and then they won't grow with only cellulose (they may need some other compounds, like a nitrogen source). Be careful with fungi, too.
If you have the proper equipment, it would be ideal to extract DNA and analyze the environmental rRNA 18s sequences. With this, you should be able to know if your bacteria is present in your sample. If so, proceed with the previous steps.
Once you had a set of suspected colonies, you must proceed with more specific culture media (wich would depend of the exact bacteria you're looking for. For example, if you're looking for Clostridium, you should try to grow your sample in an anaerobic jar and test the ability to reduce sulphur). With this approach, you may reach a point where you can't differenciate similar species. At this point, mollecular characterization is the best option, with the use of rRNA 18s again. Note that the mollecular approach, while relative expensive, can be performed in every step, so you can combine cultures and DNA analyses at will.
Lastly, if you're looking for an specific bacteria, it would be useful to know wich one is, so the community can give you more accurate responses.
The following is multiple choice question (with options) to answer.
studying a soil sample means studying the microorganisms in the | [
"dirt",
"air",
"lava",
"water"
] | A | studying a soil sample means studying the microorganisms in that soil |
OpenBookQA | OpenBookQA-1366 | ichthyology, homeostasis, osmoregulation
Pillans, R.D. and C.E. Franklin, 2004. Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient. Comparative Biochemistry and Physiology, Part A 138: 363-371.
The following is multiple choice question (with options) to answer.
Sharks live in a liquid deluged with sodium chloride because it allows them to | [
"form sharknadoes",
"have increased buoyancy",
"eat people",
"star in films"
] | B | the ocean contains large amounts of salt water |
OpenBookQA | OpenBookQA-1367 | javascript, performance, beginner, game, canvas
// Following code is a fix for [[obj1, obj3], [obj2, obj4]].
if (alreadyHadCollisions && (index1 > -1 || index2 > -1)) {
for (i4 = 0; i4 < this.collisions[collisionIndex].length; ++i4) {
obj3 = this.collisions[collisionIndex][i4];
if (obj3 !== obj1 && obj3 !== obj2) collision.push(obj3);
}
this.collisions.splice(collisionIndex, 1);
}
if (index1 > -1 || index2 > -1) {
alreadyHadCollisions = true;
collisionIndex = i3;
}
}
if (!alreadyHadCollisions) this.collisions.push([obj1, obj2]);
}
}
}
}
for (i1 = 0; i1 < this.collisions.length; ++i1) {
var targets = this.collisions[i1],
biggestRadius, scaleFactor;
obj1 = targets[0];
biggestRadius = obj1.getRadius();
for (i2 = 1; i2 < targets.length; ++i2) {
obj2 = targets[i2];
var density = Math.max(obj1.density, obj2.density),
area = obj1.getArea() * (obj1.density / density) + obj2.getArea() * (obj2.density / density);
The following is multiple choice question (with options) to answer.
Tearing an object changes its what? | [
"temperature",
"configuration",
"moistness",
"elements"
] | B | tearing an object changes that object 's shape |
OpenBookQA | OpenBookQA-1368 | tissue
Title: Tissues in plants and animals
What is the equivalent connective tissue in plants?
Connective tissue in animals are mostly made up of collagen.
What about in plants?
Connective tissue in animals are mostly made up of collagen
Tissue is not like a simple chemical mixture ; rather tissue means a group or assemblage of cells, obeying certain defining-characteristics.
Animal connective tissues contain collagen mostly in the extracellular matrix. There are also other cell-constituents like phospholipid(membranes), DNA, RNA, etc. Blood is a liquid connective tissue which do not contain collagen in its matrix (plasma)
What is the equivalent connective tissue in plants?
Connective tissue is defined as all the tissues originated from the mesoderm layer of the animal embryo.
Now plants have a different mode of development than animals (plausibly due to evolution in separate route). So no part of a plant-body is homologous with a part of animal-body. It is impossible to bring a compare.
However; plants too; have their extracellular matrix; which is more popular as plant's cell wall (that contain cellulose, hemicellulose, etc.) as well there are intercellular spaces.
Still, if you forcefully want to bring a comparison; then the ground-tissue system of plant maybe called as a rough analogy with connective tissues in animals ( Similarly epidermal tissue of plant maybe a rough analogy with epithelial tissue of animals)
The following is multiple choice question (with options) to answer.
Flowers provide substance for many animals like | [
"Whales",
"Seals",
"Dolphins",
"squirrels"
] | D | a flower 's purpose is to produce seeds |
OpenBookQA | OpenBookQA-1369 | human-evolution, skin
Title: Skin Colour in "Northern" Regions of The earth Question: Netflix has recently produced a two-part miniseries, The Evolution of US, that examines the evolution of "man". The topic of of human skin colour was covered and it was stated that 'lighter skin pigmentation was a preferred natural selection for early humans living in the "northern" regions'. The idea being that lighter skin could "absorb" sun-rays; which apparently is necessary for activating vitamin-D. Is this a true statement ? And where might I find good sources of literature to read on this topic ?
Now this particular series does not define "northern" and to be fair neither was the term "lighter skin" . My motivation in asking the question is driven by my own travels in far eastern Russia, Mongolia, Alaska, and parts of Peru and Ecuador. In each of those locations I observed numerous groups of indigenous people with dark brown skin and pitch black straight hair; which seems to contradict the statement in the series. Melanin reduces the skin's ability to make Vit D due to reduced UV penetration. This is a disadvantage in northern areas where people get less sun light, and also need to wear heavy cloths to keep warm which adds to the problem. People in Sunny regions have the opposite need as there is more than enough UV light exposure, but they run the risk of developing skin cancer, which is why having melanin provides an evolutionary advantage in these regions.
Interestingly, in the Arabian Gulf region, there is currently an epidemic of Vit D deficiency especially among those with dark skin. Although there is plenty of sun light, people tend to avoid the harsh sun almost completely by commuting strictly in cars and avoiding walking outdoors during the day. Car windows (and glass in general) are opaque to UV rays, therefor reducing the skin's ability to produce Vit D, and forcing many locals who adopt such lifestyle to take oral Vit D supplements.
Here is a link with some references to confirm the medical link between Vit D deficiency and lack of sunlight exposure:
https://www.webmd.com/food-recipes/qa/how-can-dark-skin-lead-to-vitamin-d-deficiency
The following is multiple choice question (with options) to answer.
A person with a vitamin D deficiency who is allergic to sunlight could | [
"look at pictures",
"drink more water",
"bathe more often",
"eat more cheese"
] | D | dairy is a source of Vitamin D |
OpenBookQA | OpenBookQA-1370 | geophysics, earthquakes, plate-tectonics, geography
Title: Why is the Ring of Fire there? The Ring of Fire goes through the places that have the most earthquakes. Why is the Ring of Fire there, not somewhere else?
Any help would be appreciated! This question is very similar to: Why does the "Ring of Fire" pretty much define "Pacific Rim"
The high levels of volcanoes and earthquakes are primarily due to subduction. So why is the Pacific surrounded by subduction zones?
Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it. This destruction of the ocean plate(s) occurs at subduction zones.
This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.
The following is multiple choice question (with options) to answer.
the ring of fire is made up of | [
"kelp",
"immersed lava vents",
"marshmallows",
"ice formations"
] | B | volcanoes are often found under oceans |
OpenBookQA | OpenBookQA-1371 | plant-physiology, botany
Title: Do plants produce any heat? Many plants (e.g. roses, palms) can be protected from frost during the winter if shielded with an appropriate coat that can be bought in garden shops. Do plants produce any heat that can be kept inside with these "clothes"? Cellular respiration in plants is slightly different than in other eukaryotes because the electron transport chain contains an additional enzyme called Alternative Oxidase (AOX). AOX takes some electrons out of the pathway prematurely - basically the energy is used to generate heat instead of ATP.
The exact purpose of AOX in plants is still unclear. Plants will make more AOX in response to cold, wounding, and oxidative stress. We know of at least one plant (skunk cabbage) that exploits this pathway to generate enough heat to melt snow. This link gives a pretty good overview.
(AOX is dear to my heart, since my first 3 years working in a laboratory were spent studying this gene <3)
The following is multiple choice question (with options) to answer.
A greenhouse is used to protect plants from what? | [
"nutrients",
"freezing winds",
"socializing",
"fresh air"
] | B | a greenhouse is used to protect plants from the cold |
OpenBookQA | OpenBookQA-1372 | cellular-respiration
Title: Do cold blooded animals generate any heat? In explaining energy and work to an 8 year-old I said that all conversion of energy generates heat as a by-product. For example, cars generate heat in their engines and running generates heat in our bodies. Then the 8 year-old said, except for cold-blooded animals.
So my question is, do cold-blooded animals generate any heat in their conversion of stored energy (food, fat, etc) into motion? If they generate heat, why are they cold-blooded? They do generate heat. They just do not SPEND energy specifically on heating their bodies by raising their metabolisms. This is a form of energy conservation. The metabolic rate they need to live is not nearly enough to heat their bodies.
An example of spending energy to heat the body is seen in humans shivering. Here muscle is activated not for its usual purpose, but to function as a furnace. "Warm-blooded" and "cold-blooded" is somewhat a misnomer. The correct way to think of it is...
Endotherm or ectotherm. Does the heat primarily come from within (endo) or from the surroundings (ecto). Endothermic animals include mammals. Most of their body heat is generated by their own metabolisms. Ectothermic animals include reptiles and insects. They absorb most of their body heat from the surroundings. This is not the same as saying they let their body temperature fluctuate with their surroundings, some avoid this by moving around to accomodate themselves.
Homeotherm or poikilotherm. Homeotherms want to maintain homeostasis for their body temperatures. They don't want it to change. Poikilotherms do not exhibit this behaviour, instead their body temperatures vary greatly with the environment.
We can have endotherm poikilotherms, such as squirrels, who let their body temperature drop while hibernating. Endotherm homeotherms, such as humans, where temperature is constant by means of complex thermoregulation. Ectotherm homeotherms, such as snakes (moving into shadow or into the sun to regulate temperature), and ectotherm poikilotherms, such as maggots.
The following is multiple choice question (with options) to answer.
What animal is cold-blooded? | [
"cats",
"dogs",
"tree hopper",
"rats"
] | C | an amphibian is cold-blooded |
OpenBookQA | OpenBookQA-1373 | electrochemistry, silver, electroplating
But if the free ion concentration is extremely low, as with $\ce{Ag^+}$ ions in $\ce{[Ag(CN)2]^-}$ solutions, the first $\ce{Ag}$ atom is too far from the next $\ce{Ag+}$ ion. This metallic ion is not attracted by the $\ce{Ag}$ "bump". It is attracted by the whole cathode. It touches the cathode and get discharged equally on its surface, independently from the position of the previously deposited Ag atom. The Ag deposit makes a smooth layer which looks like a mirror.
To summarize, the formation of a mirror can only occur in a solution of a silver complex where the free (non-complexed) ion concentration is extremely weak, like in $\ce{[Ag(CN)2]^-}$ solutions. Solutions of other silver compounds, like silver nitrate, will only produce rough silver deposits by electrolysis. No mirror !
The following is multiple choice question (with options) to answer.
Silver nitrate on hardened silicon will force light to | [
"refract",
"scatter",
"become hot",
"dissipate"
] | A | a mirror reflects light |
OpenBookQA | OpenBookQA-1374 | Youtube Artie Shaw Begin The Beguine, National Car Parks Limited Companies House, How To Use Jenos, Custom Frame Bags Uk, Sierra Fish En Ingles, How To Become A Psychologist In Florida, Takeout Restaurants In Moore, Ok, Kessen 2 Mei Sanniang,
The following is multiple choice question (with options) to answer.
Cans can be taken to a place known as | [
"the ocean",
"scrap yard",
"shot with BBs",
"buried"
] | B | aluminum is recyclable |
OpenBookQA | OpenBookQA-1375 | geology, geophysics, climate-change, carbon-cycle
We can see here in white numbers the most significant pre-industrial sources and sinks (at ~1000 years time scales). We can see that humans produce 9 Gigatons of carbon per year (GtC/yr), due to that extra inflow, photosynthesis is taking 3 GtC/yr more than before, and the ocean is taking an extra 2 GtC/yr as well. However, that is not enough to counteract the 9 GtC/yr we produce, and that is increasing the amount of carbon in the atmosphere at 4 GtC/yr. This means the level in the atmospheric "bath tub" is still rising.
If we were to keep those 9 GtC/yr we produce stable (i.e. not increasing production in the future). The concentration of $\ce{CO2}$ in the atmosphere will rise to a level high enough that the sinks will match the sources, for example with plants taking 5 GtC/yr and the ocean 4 GtC/yr, that would nicely balance the production. But that new equilibrium atmospheric $\ce{CO2}$ concentration would be high enough to rise Earth's temperature several degrees and force a whole reorganization of the Earth's climates.
Finally, we have to say that some of these $\ce{CO2}$ intakes, like the oceanic one, don't come for free, and have their own nasty consequences, like ocean acidification.
The following is multiple choice question (with options) to answer.
One way humans may be polluting the Earth is | [
"using solar energy",
"antibacterial soap",
"riding bikes",
"walking"
] | B | pollution is when humans pollute the environment with pollutants |
OpenBookQA | OpenBookQA-1376 | electricity
Title: Can touching a single power line (on the street) kill you? Statement: You need to touch two power lines at the same time to get electrocuted. I am kinda doubting this now because, in the video linked below, it looks like the person is only touching one line but still gets an electric shock. Is this possible? and also the person is on a tree and aren't trees insulators? This video isn't sensitive or anything, it actually funny, so please don't hesitate to watch. Thanks!
Video Unless there is sufficient insulation (electrical impedance) between you and the earth when you touch a high voltage wire, yes you may get electrocuted. This is because most electrical power systems in the world are earth grounded (referenced to earth). The higher the voltage the greater the impedance to between you and earth ground needs to be. At 60 Hz it only takes 50-100 mA of current in a path through the heart to cause ventricular fibrillation.
If you are isolated from ground and touching two wires with your bare hands, electrocution is possible if the voltage difference has the potential to cause a lethal electric shock and the insulation on the conductors is insufficient to limit the current to below the threshold for a lethal electric shock.
oh okay, bats die when they hang on the cables, but they do not
provide any connection between live and ground, how is this possible?
Regarding your above comment to Solar Mike, it is ONLY possible for the bat to be electrocuted if the bat is simultaneously in contact with the high voltage wire and another wire or grounded object where the voltage between them has the potential to cause a lethal electric shock.
Bats are physically different than the typical birds you observe on HV wires. For one I understand they may have wingspans much larger than ordinary birds. So if they are on a HV wire and spread their wings, there is a higher likelihood that their wings will simultaneously contact more than one HV wire at a time, or some grounded part, causing lethal electric shock. Regardless of the reason for their deaths, they must simultaneously be in contact with two conductors with a potential difference capable of causing a lethal electric shock.
Hope this helps
The following is multiple choice question (with options) to answer.
A person wanting to protect humans from electrocution through wire contact would wrap the wire in | [
"a tin can barrier",
"a metal beam with steel",
"a copper rope with barbs",
"a log filled with sawdust"
] | D | wood is an electrical energy insulator |
OpenBookQA | OpenBookQA-1377 | 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.
Carnivores devour omnivores which eat | [
"flora",
"rocks",
"crustaceans",
"sand"
] | A | omnivores eat plants |
OpenBookQA | OpenBookQA-1378 | visible-light, sun, weather
Title: Why are clouds lighter than the sky during the day but darker at night This is probably a very basic question but I couldn't find a good answer to it, most search results are about rain clouds or clouds appearing red at night (something I've never seen except for during sunset but apparently it's common in bigger cities).
Basically what I'm wondering is why clouds during the day appear lighter than the sky (white vs light blue) while clouds at night and during the evening appear darker than the sky (see image).
Image quality is low because I took it with my phone through my window.
I guess the clouds could be blocking the light and therefore appear darker but in that case, shouldn't the same thing be happening during the day? There could be quite a few things going on.
Off the bat there's no incoming light for them to scatter: during the day, clouds are white because the water droplets are big enough for all visible light to cause Mie scattering, but if you don't have much light falling on them, you can't observe the scattering and you can't observe light passing through either.
Then you could consider the fact that in some places, it rains more in the evening/night than during the day (if you have hotter surface temperatures during the afternoon, you see cloud formation and precipitation during the late evening, and with the lower temperatures in the night, the air is more likely to become saturated, see Dew Point), and clouds which precede rain are thicker and denser. They don't allow much light pass through.
And lastly, there's less ambient light which they can reflect back towards you.
The following is multiple choice question (with options) to answer.
A storm rolls in and the skies are filled with dark clouds which | [
"melt",
"flood",
"precipitate",
"scurry"
] | C | clouds produce rain |
OpenBookQA | OpenBookQA-1379 | electric-circuits, potential, electrical-resistance, conductors
These analogies are not exact and are only intended to give you a better feel as to what is happening.
Hope this helps.
The following is multiple choice question (with options) to answer.
Electrical conduction may occur when | [
"a person takes a trip",
"a person gets a dog",
"a person presses a key to a socket",
"a person moves plastic into a car"
] | C | electrical conduction is when metals conduct electricity through metal |
OpenBookQA | OpenBookQA-1380 | 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.
A field of flowers has pollen filled flowers. The most likely thing to do the seed spread would be | [
"striped falcons",
"human children",
"wild boars",
"avian creature"
] | D | when pollen sticks to a hummingbird , that pollen will move to where the hummingbird moves |
OpenBookQA | OpenBookQA-1381 | geology, fossil-fuel, petroleum
For some transport applications, the energy density is still a winning attribute of hydrocarbons: most notably, powered flight for freight and travel.
We already have two routes to non-fossil hydrocarbons: biological sources, and direct chemical synthesis. Each involves capturing atmospheric CO2, and combining with water, to generate a blend of hydrocarbons.
Now, we already have means of creating hydrocarbons suitable for flight (e.g. Jet-A and Jet-A1 fuels). And there are already demonstration plants that have closed-loop generation of synthetic hydrocarbons, for use in electricity-grid-balancing, by using surplus electricity to synthesise methane, which is then burnt in gas turbines when required. Similarly, Tony Marmont's team have been synthesising petrol (gasoline) from air, water, and electricity.
However, none of those things mean that hydrocarbons necessarily have much of a future, beyond plastics production. Because hydrocarbon-powered aviation has a lot of environmental problems beyond just CO2 emissions, in particular it makes other contributions to exacerbating global warming. And there are lots of options for energy storage within the electricity supply chain.
The following is multiple choice question (with options) to answer.
Alternative fuel is usually a renewable what? | [
"sound",
"meal",
"drink",
"asset"
] | D | alternative fuel is usually a renewable resource |
OpenBookQA | OpenBookQA-1382 | human-biology, eggs
In order to form a zygote (fertilized egg) to develop properly into a fetus it has to be an environment to meet it needs. In a female uterus all these needs are met but replicating them might be difficult. An artificial womb would have to be able to provide nutrients, oxygen, and channels for the development process of a fetus as well as system to expel (birth) the fetus once its development is complete. So can today's technology and science do all this? In theory yes, if resources and time where dedicated (and red tape cut) it would be possible to develop a fertilized egg in an artificial environment within the foreseeable future. There have been multiple experiment where artificial wombs were implanted with fertilized eggs and began to grow but were stopped due to legality.
I encourage you to read the following Wikipedia and motherboard articles regarding artificial wombs and ectogenesis.
https://en.wikipedia.org/wiki/Artificial_uterus
http://motherboard.vice.com/read/artificial-wombs-are-coming-and-the-controversys-already-here
*Note there is a lot of biology I did not mention regarding zygote to fetus development which is the biggest question/obstacle that ectogenesis might face
The following is multiple choice question (with options) to answer.
Which of these use a womb instead of eggs for fetal development? | [
"chickens",
"falcons",
"lemurs",
"hawks"
] | C | live birth means developing inside the mother instead of an egg |
OpenBookQA | OpenBookQA-1383 | meteorology, snow, radar
Also note that winter precipitation adds an extra complication because the particles are lighter in weight and can thus be blown about more by vertical and horizontal winds. Raindrops (and hail) are quite likely to fall unless extreme updrafts exist because they are heavy. But drizzle, snow, and sleet may be blown around quite a bit. Without a time-intensive dual-Doppler analysis, you cannot know the wind motion in the storm thoroughly, and therefore will have varying results at times.
And finally, the big wrench is unfortunate inherent to how radars work. They measure the percentage of their sent energy that is reflected back to them. That's great because that's directly connected to the diameter of the item falling (to the 6th power). But unfortunately the grand problem is that in a storm, there is a huge variety of drop/flake sizes mixed together at once... such that we can't extract which combination of particle sizes created it (and thus can't calculate volume to actually know the rain/snow amount that falls). It could be like 6 medium size flakes causing the 10 dBZ echo... or 2 large flakes and 10 small flakes... and each combination is a different volume/snow total. (to see the nitty-gritty math details on this, read more here.) So we can never know for sure the exact rain/snow falling using just radar. The good news is we've at least done lots of experiments and come up with some fairly useful best-practice formulas for using the Z-R ratio in different scenarios. Good, but not perfect.
The following is multiple choice question (with options) to answer.
Sleet is | [
"potentially dangerous",
"poison",
"hot",
"unhealthy"
] | A | sleet is made of ice |
OpenBookQA | OpenBookQA-1384 | biochemistry, food
Title: Who creates first nitrogen compounds in the food supply chain As I understand the food supply chain, organic compounds have to be created from a unlimited source (air, water...).
For instance, I figure that plants transform CO2 from air to organic carbon compounds, mainly carbohydrates, which are then the main source for most other life forms.
But I never heard about a plant turning atmospheric N2 to nitrogen compounds.
Where nitrogen compounds come from, and from which source ? There are nitrogen fixing bacteria who turn N2 into NH3. Some are free-living in soil, others live symbiotically with plants.
https://en.wikipedia.org/wiki/Nitrogen_fixation
The following is multiple choice question (with options) to answer.
Processes in the food chain begin with | [
"leafy flora",
"purple horseshoes",
"yellow bees",
"breakfast"
] | A | In the food chain process a green plant has the role of producer |
OpenBookQA | OpenBookQA-1385 | newtonian-mechanics, energy-conservation, friction, everyday-life, physical-chemistry
Title: Conservation of energy when we drive a car When we drive a car, we use gasoline as the source of energy. When we arrive at the destination, we lose some of the gasoline, used to move the car from one point to another. Then how energy is conserved, if we spend energy to move the car? What does it mean to "spend energy"? In the concrete example, the engine converts the chemical energy in the gasoline through combustion into kinetic energy of the car.
While the car is moving, it feels friction with the surface and air, so some of the kinetic energy of the car goes into friction (heat, air movement, etc).
When you stop the car, the kinetic energy completely goes into friction in the brakes, asphalt and air (again, as heat or kinetic energy of the air molecules, etc).
Conservation of energy means that in a closed system the energy stays constant. If you look just at the car and not also at the surroundings, that is not a closed system, and that principle is not applicable here. However, you can look at the surroundings too; then it all works out.
The following is multiple choice question (with options) to answer.
A car converts gasoline into motion and heat through what? | [
"explosive charisma",
"cooling",
"incineration",
"warming"
] | C | a car engine usually converts gasoline into motion and heat through combustion |
OpenBookQA | OpenBookQA-1386 | forces, aerodynamics, lift
Lets take $C_l$=1,$v$ =1, $S$ =1 and mass=1 $kg$;
For $g$ =9.81 $m/s^2$
Lift force is 0.21775 $N$, weight is 9.81 $N$ and resulting upward force is -9.59225 $N$
For case 2: $g$ =20 $m/s^2$
Lift force is 0.066, weight is 20 $N$ and resulting upward force is -19.934 $N$
Answer:
The following is multiple choice question (with options) to answer.
A crane starts off weighing thirty pounds, then later weighs twenty pounds. When travelling, the crane will fly | [
"taller",
"better",
"slower",
"louder"
] | B | as the weight of an animal decreases , that animal will fly more easily |
OpenBookQA | OpenBookQA-1387 | It just turns out nicely for C that he is one of the people whose hat colors D and C both know about.
To introduce a modified challange: if the task were to yell out C's hat color right away, D would know for certain, C would have the increased probability of $2/3$ and A and B would be stuck with the random guess of $1/2$. D still knows more.
The following is multiple choice question (with options) to answer.
A learned behavior is exhibited when a human displays that they can: | [
"squinting in bright light",
"digesting food in the stomach",
"change a car tire",
"inhaling and exhaling during sleep"
] | C | skills are learned characteristics |
OpenBookQA | OpenBookQA-1388 | speciation, artificial-selection
Title: Is there any artificial species (in particular, an artificial species of animal)? Dogs were artificially selected from wolves, but a dog and a wolf can produce fertile offspring, and thus are of the same species. I had heard that the aurochs and cattle were different species, but I could not find this information anywhere. I had heard also that some artificially selected flies are considered to be a new species.
Is there any human-made species (especially a species of animal) which is not able to produce fertile offspring witch any other species, in particular with the one from which it evolved?
EDIT: (A similar question in different words.) Is there any human-made animal lineage which was conceived by artificial selection and which is broadly accepted as not being a race or subspecies, but a species on its own. Artificial selection leading to new species - Domestication
As you talk about dogs in your intro, let's consider them.
You will fail to breed a great dane and chihuahua for obvious mechanical reasons. You will also fail to breed a chihuahua with a wolf. So, yes artificial selection have lead to reproductive isolation.
Artificial selection leading to new species - lab experiment
Artificial selection have also lead to reproductive isolation in non-domesticated species. See for example the post Have we ever observed two drosophila lineages that evolved reproductive isolation in labs?
Concept of species
As a side note... Above, I consider the so-called 'biological species concept'. For a discussion on the definition of species, please have a look at this post.
The following is multiple choice question (with options) to answer.
Dogs reproduce differently from | [
"bears",
"wolves",
"cats",
"earthworms"
] | D | different organisms reproduce differently |
OpenBookQA | OpenBookQA-1389 | thermodynamics, electromagnetic-radiation
Suppose your 100W light source emits all its energy as wavelengths longer than 4$\mu$m where the absorptance is virtually 100%. That means the glass is absorbing the whole 100W and heating up at some corresponding rate.
Between about 200nm and 2000nm the absorption is only about 10%, so if if you tweak your light bulb to emit all its energy as wavelengths in this range it would only absorb 10W. So it would still heat up but at only one tenth the speed of of the other bulb.
So you could still solve the puzzle, but you might need a sensitive thermometer. To make the puzzle impossible to solve you would need a glass that absorbs no radiation at all, and as far as I know no such glass exists.
The following is multiple choice question (with options) to answer.
A light bulb will be lit up if it is all aside from | [
"turned on",
"on a shelf",
"connected to electricity",
"screwed in"
] | B | a light bulb requires electrical energy to produce light |
OpenBookQA | OpenBookQA-1390 | geology
Title: Where do riverbed stones come from? Have they always been here since the river was formed? Are some newer than others? Riverbed 'stones' - I assume you mean things like pebbles, boulders, etc. are pieces of rock that have weathered out and been deposited in the river. Some come from rock that is very close to where they are located and some have been transported from very far away. In general (and it is a very broad generalization) the rounder the stone, the longer it has been in the river and the more likely it is to have come from far away. Of course that depends on the hardness of the rock, and other factors, too.
Some rocks are newer than others. Some have been formed quite recently and some are billions of years old.
The following is multiple choice question (with options) to answer.
A river rushes and pebbles are smacked around one another until | [
"they are wet",
"they are clear",
"they are rough",
"they are velvety"
] | D | contact between rocks over long periods of time causes rocks to smooth |
OpenBookQA | OpenBookQA-1391 | electric-circuits, electric-current, electrical-resistance, batteries, short-circuits
Title: The importance and the role of a switch in an electrical circuit There is this simple test:
Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed:
a] The brightness of $A$ and $B$ remains the same, while $C$ goes out.
b] The brightness of $A$ and $B$ remains the same, while that of $C$ is halved.
c] The brightness of $A$ and $B$ decreases while $C$ goes off.
d] The brightness of $A$ and $B$ increases while $C$ goes off.
For my opinion the answer to this question is D because the switch (which has a resistance of $0\, \Omega$ has a node connected before the third bulb C) that "interrupts" the circuit. But, going into detail, according to Kirchhoff's first law the current should also go on the third bulb as in the first red node it divides into two currents $I_1$ and $I_2$. The current $I_1$ goes for example in the key $S$ and $I_2$ in the third bulb. The key and the third bulb have the same potential difference. I believe that the current $I_2$ passes through the third bulb but the current passing through it is so small that it does not turn on.
I made a point. When an individual is operated on at the heart and puts a by-pass (a bridge), blood will flow on the tube that detects the by-pass and the occluded artery (the third bulb) where blood will flow slowly, over time it will atrophy.
If the circuit were like the one drawn in the picture I would answer the b).
My question is: I have not very clear the rule of a switch in a eletric-circuit.
In fact, I find it difficult to give an answer to the following image.
The following is multiple choice question (with options) to answer.
A switch turns something on because: | [
"electrons are made to excite",
"metal closes the circuit",
"the engine needs to run",
"the circuit is opened completely"
] | B | pushing a button sometimes completes a circuit |
OpenBookQA | OpenBookQA-1392 | water, chemical-biology, precipitation
Title: In the wet medium of an ocean, how does a hard shell form? In general, if you were to try make something hard in a liquid medium (especially water) it is quite difficult to make the material solid.
Things such as mollusks though, have no problem generating hard shells in a wet medium.
What exactly are the physics behind this formation? Carbon dioxide from the atmosphere (or from decaying matter in the ocean) reacts with water to form carbonic acid:
$$ \ce{ CO2 + H2O -> H_2CO_3 }$$
and this reacts with calcium ions to form calcium carbonate:
$$ \ce{H2CO3 + Ca^{2+} -> CaCO3 + 2H+ }$$
The solubility of calcium carbonate is about $13~\mathrm{mg \over L}$, so if the concentration of calcium carbonate is greater than this the excess will precipitate out as solid calcium carbonate.
Shell-forming organisms actively absorb calcium from the water around them, so they are able to increase the concentration of calcium carbonate to above $13~\mathrm{mg\over L}$ and precipitate the excess to form their shells. They can get the carbon dioxide from the water around them or from their own metabolism. The actual details of shell formation is far more complex than this as it's controlled by processes with the cells of the organism rather than just being uncontrolled precipitation. I'm not sure how well the details are understood even today.
Incidentally, this is why shelly fauna are not keen on the acidification of the oceans that results from increased atmospheric carbon dioxide. The solubility of calcium carbonate is strongly $\mathrm{pH}$-dependent and rises sharply as the water gets more acid. Given that the shell is usually intended to stop other animals eating you, having your shell dissolve is generally not good for life expectancy.
The following is multiple choice question (with options) to answer.
Limestone is formed by water evaporating from a solution of water and mineral and a hard sedimentary rock used as building material and for making | [
"lipstick",
"cement",
"lemon-lime soda",
"mineral water"
] | B | limestone is formed by water evaporating from a solution of water and minerals |
OpenBookQA | OpenBookQA-1393 | # Probability: If I have a friend that likes half of the food he tries, what is the probability that he likes three of five foods that he's given?
I was thinking 1*1*1*2*2 = 4 out of 32, with LLLDD, LLLLL, LLLDL, LLLLD, with L as like and D as dislike. But if I can do LLLLD and LLLDL, why couldn't I do LDLLL or DLLLD? Any explanation would be appreciated.
EDIT: At least three (Sorry, forgot to mention)
-
Do you want the probability that he likes exactly three of the five, or at least three? – Brian M. Scott Jan 29 '13 at 0:04
He sounds too picky, I doubt he will like any of them. – Anon Jan 29 '13 at 0:04
Yes, we have to take into account $DLLL$, $DLDLL$, $DLLDL$, and so on. (There are $10$ of these like $3$, dislike the others.) And they are used in calculating the probability. – André Nicolas Jan 29 '13 at 0:09
Your confusion comes from the following: You are calculating the event that he will like the first, second, and the third food, and then you say, "I don't care about the last two foods," and you put $2$ and $2$. Here (in your question), the order is not important. – Anon Jan 29 '13 at 0:19
Because of this reason, your current solution does not take into account the case e.g. LDLLL, as you have mentioned. – Anon Jan 29 '13 at 0:21
This to me looks like a Bernoulli trial with $p=1/2$.
Probability that your friend like $k=3$ of $n=5$ foods he tries is
The following is multiple choice question (with options) to answer.
A person who wants to eat a watermelon may consider spitting out its | [
"dark pips",
"good taste",
"coco pebbles",
"red fruit"
] | A | a berry contains seeds |
OpenBookQA | OpenBookQA-1394 | zoology, pathology, herpetology
Title: How do pet gecko lizards pose a health risk? Does having gecko lizards living in your house pose any health risk? If you're referring to keeping geckos as pets, like all reptiles, amphibians and birds, they come with a small but finite risk of contracting salmonellosis. Having said this, the infection is easy to avoid if you maintain basic hygiene.
On a personal note, I know dozens (perhaps hundreds) of people who keep or have kept reptiles as pets and have yet to meet anyone who contracted salmonellosis. Basically, if you wash your hands after touching the gecko, keep it away from food preparation areas and don't put the lizard in your mouth, you should be fine.
If you're talking about geckos living free in your home, as is common in many tropical places, I have never heard of any health risks associated with them. If anything, I would think that the geckos would reduce health risks by eating insects such as cockroaches and mosquitoes that are prominent disease carriers.
The following is multiple choice question (with options) to answer.
A boy wants to feed a gecko so he gives it | [
"waxworms",
"dog food",
"chickens",
"markers"
] | A | lizards eat insects |
OpenBookQA | OpenBookQA-1395 | 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.
in order for an animal to stay healthy it needs to | [
"consume enough food",
"exercise regularly",
"sleep long hours",
"reproduce"
] | A | an animal requires enough nutrients to maintain good health |
OpenBookQA | OpenBookQA-1396 | automotive-engineering, car
Title: How do hybrid cars achieve greater fuel efficiency? In this question I’m comparing non-plug-in hybrid fuel/electric vehicles with fuel-only vehicles. Also, I’m not disputing that hybrid cars are more fuel efficient, I’m just trying to understand how.
If I remember two things from high school physics, it’s:
Creating energy from nothing is against the law.
Converting energy from kinetic to stored energy and back again is always less that 100% efficient - you end up with less kinetic energy than you put in, the rest being “lost” to the environment in the form of heat or whatever.
The following is multiple choice question (with options) to answer.
when fuel efficiency increases, gasoline use in cars will | [
"stay the same",
"cause more windstorms",
"increase",
"decrease"
] | D | as mileage per galon of gasoline increases , the amount of gasoline used will decrease |
OpenBookQA | OpenBookQA-1397 | thermodynamics, evaporation, gas, liquid-state
On the water surface, knowing the temperature, we can estimate the vapor pressure and vapor mixture fraction. Then there will be an diffusion process for the water vapor to move out and for the ambient air to move in. Because the water surface doesn't allow the air to further move, a circulation forms. When the water vapor moves out, the water vapor pressure drops, so more liquid water evaporates to fill up the loss of water vapor. The evaporation associates latent heat so water surface area temperature drops (you may see dew on the bowl wall). Then a heat transfer process starts which may initiate water circulation as well.
As this is complex, doing test might be a quick way to get the K value if you assume it is a constant, which is questionable.
The following is multiple choice question (with options) to answer.
To see evaporation you can wrap | [
"a metal in plastic",
"a bowl of water in plastic",
"a cat in a bag",
"money in plastic bags"
] | B | evaporation causes amount of water to decrease |
OpenBookQA | OpenBookQA-1398 | geology, earth-history, paleontology, stratigraphy, mass-extinction
Why did this idea develop only in the 1980s? It was known since the 19th century that extinctions had occurred. Even the stratigraphic time is divided into units constrained by different fauna found in the fossil records. What was it that made the change from a "gradualist" perspective of things to the "catastrophic" point of view? The idea of mass extinction is not that recent actually: Cuvier (1798), Buckland (1823) and d'Orbigny (1851) for instance were already talking about global catastrophes in earth history, linked to extinctions. But during the same period, Brocchi (1814) and Lyell (1832) proposed that extinctions of species occurred individually and were a gradual process (either only linked to an intrinsic taxa longevity for Brocchi, or variations in the environment for Lyell). Darwin, following Lyell, also thought that extinctions were gradual and not catastrophic. He also noted the fact that hiatuses in the fossil record or artificial concentration in some strata could show apparent extinction event.
The issue with mass extinction is that to demonstrate their existence you need to be able to demonstrate extinction synchronicity and quantify the amount of species going extinct (to show that it is more than just background noise).
Demonstrating the synchronicity of one mass extinction is what Alvarez et al. 1980 managed to do thanks to the Iridium layer at the K/Pg boundary. More generally, the possibility of correlating extinctions precisely is something that evolved in par with the evolution of stratigraphic tools, and the 1970-1980s is the period during which high-resolution stratigraphic methods arose (chronostratigraphy, magnetostratigraphy, stable isotope stratigraphy for instance).
Quantifying mass extinction is what Jack Sepkoski did with his compendium of marine invertebrates (see Sepkoski 1978, 1979; Raup & Sepkoski 1982, etc.). Today, the PbDb (PaleoBiology DataBase) is the project which focusses on that specific issue (see for instance Alroy et al. 2001). It still remains today the main hurdle in studying mass extinctions.
Alroy, J. et al., 2001. Effects of sampling standardization on estimates of Phanerozoic marine diversification. PNAS, 98(11): 6261-6266.
The following is multiple choice question (with options) to answer.
A tortoise died many years ago, but it is easy to tell that what was left behind was from a tortoise because in the rock there are | [
"muscles",
"skeletal system",
"organs",
"candy pieces"
] | B | organisms can be preserved in sedimentary rock |
OpenBookQA | OpenBookQA-1399 | biochemistry, mitochondria, bioenergetics, chloroplasts
A hypothesis is an assumption made before any research has been done.
It is formed so that it can be tested to see if it might be true. A
theory is a principle formed to explain the things already shown in
data. Because of the rigors of experiment and control, it is much more
likely that a theory will be true than a hypothesis.
But is this dogmatism justified, and how does it apply to the current problem? Mitchell’s proposal was made to be tested (as in a hypothesis) but it was intended to explain the observed phenomenon (as in a theory) of oxidative phosphorylation.
An extensive article in Wikipedia begins with a more modest statement:
A hypothesis (plural hypotheses) is a proposed explanation for a
phenomenon.
And chemi-osmosis is a proposed explanation for the phenomenon of ATP synthesis in double-membrane systems; so by this token Mitchell’s choice of words seems justified.
Major dictionaries record how words are or were used in practice. In some contexts there are sharp distinctions in usage of particular words, where in others the same words are used interchangeably. In modern biological science, unlike philosophy, logic or the numerical sciences, laws, theories and hypotheses are generally of no great concern, and the writers quoted may merely feel that the word ‘theory’ (‘Einstein’s’ theory, ‘Darwin’s theory’) has more gravitas than ‘hypothesis’, a word they perhaps use to describe ideas about relatively humble scientific problems of their own.
…or they may just find it easier to spell.
The following is multiple choice question (with options) to answer.
Examples of hypothesis is | [
"September 11th was a terrorist attack",
"Rain falls from the sky",
"Fish swim in water",
"Drinking sugary drinks daily leads to obesity"
] | D | hypothesis means scientific guess about the cause and effect of an event |
OpenBookQA | OpenBookQA-1400 | 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.
The circulatory system brings oxygen to the body from where? | [
"brain",
"chest",
"hands",
"stomach"
] | B | the circulatory system carries oxygen from the digestive and respiratory systems to the rest of the body |
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