source string | id string | question string | options list | answer string | reasoning string |
|---|---|---|---|---|---|
OpenBookQA | OpenBookQA-801 | thermodynamics, combustion
Title: Recovering mechanical energy from natural gas water boiler Is there any heat energy lost to the mechanical force of pushing a piston in a combustion engine?
In other words, would a natural gas burning as a flame produce more heat than the same amount of natural gas that was burned when driving a combustion engine?
The context of this question is around fuel efficiency of natural gas water boilers.
My current understanding is that a naked natural gas flame is burning inside the unit, and heats water that is contained within a series of pipes, which in turn is cooled in a heat exchanger, and that same heat exchanger heats the incoming cool water.
I'm wondering, would if it make any sense at all to burn that natural gas inside a combustion engine and use the heat of the combustion engine used to heat the water to the same extent as a naked flame.
More generally my goal is to solve the question, can we heat water the same extent by burning the same amount of natural gas and get free mechanical energy?
Thanks Check out combined heat and power systems... generates electricity and makes use of the waste heat to heat water - but is only really efficient when there is sufficient hot water demand ie heating load.
The following is multiple choice question (with options) to answer.
heat and pressure change the remains of what into natural gas? | [
"leaves",
"cans",
"books",
"cars"
] | A | heat and pressure change the remains of prehistoric living things into natural gas |
OpenBookQA | OpenBookQA-802 | fluid-dynamics, pressure, biophysics, explosions, shock-waves
During recompression to higher pressures,
the subcutaneous gases were, of course, also
recompressed and the animals quickly and
dramatically deflated to their normal appearance, still remaining, however, in an obvious state of flaccid paralysis, unconsciousness,
and apnea. This deflation process appeared to
begin rather gradually with the onset of recompression. At 25 to 30 mm. Hg absolute, deflation became more rapid ; at approximately
70 mm. Hg the animals appeared to have returned to their normal size. At 45 to 50 mm.
Hg, however, a major portion of the deflation
is complete, suggesting that water vapor is
probably the predominant gas concerned with
the excessive distention of the animals. The
exact pressures at which the deflation process
and the condensation of water vapor occurred
was influenced, in part at least, by the subcutaneous and deep body temperatures which,
in turn, were probably affected by the duration
of the low pressure exposures and the evaporative cooling of the body surfaces.
The rapidity of recovery during or after
recompression was generally dependent on the
duration of the low pressure exposure, the rate
of recompression, and on whether or not the
animals were recompressed with oxygen or air.
As might well be expected, the shorter the
exposure time and the faster the recompression
with oxygen, the more rapid and less complicated was the recovery period. Animals that
were exposed to the low pressure for 90 seconds
or less often began to breathe spontaneously
during the recompression to ground level.
When the exposures to the reduced pressure
were longer than 90 seconds, the depressed state
of the animals was intensified and apnea persisted for a prolonged period of time after
recompression. Under these conditions, when
first examined at ground level, the animals
were usually apneic with variations in heart
rate ranging from bradycardia to tachycardia.
They remained apneic for varying periods of
time, but spontaneous respiration always began
in less than 2 to 3 minutes, provided there was
a heartbeat. Otherwise, when no heartbeat
was detectable, the animals invariably failed to
survive. During the course of recovery, both
the heart rate and respiratory frequency increased steadily for the first 2 to 5 minutes.
Some of the animals exhibited a state of decerebrate spasticity when stimulated by being
touched or handled. Most of the animals
The following is multiple choice question (with options) to answer.
the inability of a once breathing organism to function can be described as? | [
"a state of the union",
"a state of activity",
"a state of agility",
"a state of being dead"
] | D | if a living thing dies then that living thing is dead |
OpenBookQA | OpenBookQA-803 | 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.
which one of these activities can lead to animal gathering seeds | [
"Bees making nectar",
"bees making honey.",
"bees stinging human",
"Bees collecting nectar"
] | D | An example of seed dispersal is is an animal gathering seeds |
OpenBookQA | OpenBookQA-804 | zoology, digestive-system, pets
Title: Is it safe to feed an adult fire salamander with slime maggots? As a reminder, maggots feed of a flesh, while fire salamander consumes his prey alive, without killing it.
Can it happen that the maggot will start eating the salamander from the inside? Although I am afraid I don't know much about fire salamanders specifically, it is certainly possible for ingested fly larvae (or larvae hatching from ingested eggs) to survive ingestion and subsequently cause intestinal damage. Parasitic infestation by fly larvae that grow inside the host while feeding on its tissue is called myiasis. Enteric myiasis (also called gastric, rectal, or intestinal myiasis to indicate the affected part of the digestive system) occurs occasionally in humans following the ingestion of cheese infested with cheese fly maggots. Casu marzu, a traditionally produced Sardinian cheese, is supposed to have live cheese fly maggots in it, and cases of bloody diarrhoea following its consumption are known. If they're dead the cheese is considered unsafe to eat (although personally I'd correct that to 'more unsafe').
The following is multiple choice question (with options) to answer.
Which would an alligator eat | [
"spider",
"crab",
"squid",
"tilapia"
] | D | alligators eat fish |
OpenBookQA | OpenBookQA-805 | immunology, virology
Title: Why do people dying of immune deficiency diseases appear sick? Please forgive the obviously silly appearance of this question, and/or of the tenor which may come across as flippant or dismissive of real world suffering. My intention is none of the above.
As a layperson, I have always understood that the expression of our various colds/flus etc, while frequently mis-understood as being caused by the virus, are actually just manifestations of our own immunity fighting same. In other words, all the snot, and fever and inflammation are not caused *by the virus, they are a reaction *to the virus, as we fight it off.
My question then is why do people with AIDS (or similar immunity destroying affliction) appear sick? If they have weak or non-existent immune systems, following the above logic, would one expect to see them passing away while looking entirely healthy? Many of the symptoms of disease are indeed related to inflammation, but inflammation depends heavily (though not solely) on the innate immune response. Patients with AIDS and some of the other immunodeficiencies lose their adaptive immune response, not their innate response. Therefore they are capable of mounting an inflammatory response that is not effective in clearing pathogens (because it doesn't have help from the adaptive immune system) but can still cause symptoms.
More importantly, many symptoms of disease are not caused by the inflammatory response, but are related to organ and tissue damage caused by the infection. A patient with pneumonia may have a reduced inflammatory response but will still have difficulty breathing and signs of reduced oxygen supply simply because the lung tissue has been damaged by the pathogen.
The following is multiple choice question (with options) to answer.
Who's health does illness impact? | [
"an animate object",
"a blue object",
"a dead object",
"an inanimate object"
] | A | illness has a negative impact on an organism 's health |
OpenBookQA | OpenBookQA-806 | zoology, mathematical-models, software, imaging
Title: What would it take to recognize a deer by its photo? I am trying to recognize a deer by its antlers or any other means.
Elaborating:
I was hoping to use their antlers to recognize them but I have heard that most deers shed their antlers every year so it would be difficult to recognize it from the last year's photo unless these antlers retain the same pattern every year.
If not the antlers, what other characteristics should I be looking for?
Is there any software that can help me in recognizing a deer? There is a lot of variation in how and when deer shed their antlers. In most arctic and temperate-zone species, antler growth and shedding is annual, and is controlled by the length of daylight. In tropical species, antlers may be shed at any time of year, and in some species such as the sambar, antlers last several years. Some equatorial deer never shed their antlers.
The horns change every year and, especially, increase the number of branches (and consequently, change their shape). You can't recognize them by antlers, but by other features, such as color of the hair or the lineaments. Like us, animals have individual morphological differences that are recognizable and listable.
Biologists specializing in studies of particular animal species not only take photos, but also make drawings and write descriptions of behavior, to identify individuals within herds.
An optical examination, however, of the subject through drawings and photos (and if possible, direct observation), is more useful than a PC program. This involves identifying particular similarities and equalities that are not "identical". This is possible to do visually on a large (but limited) number of specimens. The human eye is the best computer.
The following is multiple choice question (with options) to answer.
A herd of deer may be forced to search for a new home if | [
"resources in an area become too few to maintain the herd",
"water in an area becomes slightly briny",
"more babies are born in the spring",
"moose move into an area that deer are in"
] | A | if the amount of available food and water decreases in an environment then animals may leave that environment to find food and water |
OpenBookQA | OpenBookQA-807 | the-moon, night-sky
And another useful reference at planetarium.madison.k12.wi.us:
At the beginning of Winter, when it's nighttime all of the time, the moon would be in the sky for the 2 weeks closest to Full Moon, and then below the horizon for the next 2 weeks. And at the beginning of Spring (click on the graphic), when the sun is at sunrise all of the time, the moon would be up in the sky for the 2 weeks closest to First Quarter (waxing), and then below the horizon for the next 2 weeks.
The animated graphic above shows what we would see from the North Pole if we went out every day at noon, for 14 days in a row, from March 1st to March 14, 2006. We start with a thin crescent moon near the horizon, and end with a full moon near the horizon. Halfway through, the First Quarter moon would be when the moon is highest above the horizon.
Keep in mind, that if you were observing the moon constantly, throughout a 24 hour period, the moon would seem to move to the right in the sky along with the sun, stars, and planets due to the Earth's rotation. Nothing would seem to rise and set: they would just seem to circle around you.
The following is multiple choice question (with options) to answer.
Thirteen times a year, roughly, the moon | [
"crashes into the Earth",
"is orbited by the Earth",
"lights up the Earth",
"completely rotates the Earth"
] | D | the moon orbiting the Earth approximately occurs 13 times per year |
OpenBookQA | OpenBookQA-808 | zoology, ecology, species-distribution, migration
Title: How do animals end up in remote areas? I was thinking specifically about random marshy water holes on farmers fields. It seems that you can visit just about any one of these and you will find frogs if you look hard enough.
They usually don't seem to be connected to each other. If it were any other land animal I would figure they walk from one spot to another, but in the case of frogs, I don't imagine their range is very vast. But often these marshy spots can be separated by fairly large distances to a frog.
So this brings me to my question: how do each of these spots end up with frogs in them? I don't imagine a frog is going to go hopping over a hill to get to a marsh on the other side, is it? This question pertains to organism dispersal, which is a very active field of study with relation to it's impact on conservation efforts. Much of what I will say below has been covered in this wiki.
Definition: From the Wiki
Technically, dispersal is defined as any movement that has the
potential to lead to gene flow.
It can be broadly classified into two categories:
Density dependent dispersal
Density independent dispersal
The question of frogs and fishes both refer to Density independent dispersal, while an example of density independent dispersal can be the competition for habitat space between big cats and humans (this is a WWF pdf)
From the wiki:
Density-independent dispersal
Organisms have evolved adaptations for dispersal that take advantage
of various forms of kinetic energy occurring naturally in the
environment. This is referred to as density independent or passive
dispersal and operates on many groups of organisms (some
invertebrates, fish, insects and sessile organisms such as plants)
that depend on animal vectors, wind, gravity or current for dispersal.
Density-dependent dispersal
Density dependent or active dispersal for many animals largely depends
on factors such as local population size, resource competition,
habitat quality, and habitat size.
Currently, some studies suggest the same.
This study in particular studied the movement and habitat occupancy patterns within ephemeral and permanent water bodies in response to flooding. They found that during flooding these frogs moved out to flooded ephemeral water bodies and later on moved back again to the permanent ones.
Other suggested readings for those highly interested in the subject may include this (a phd thesis) and this (a project report)
The following is multiple choice question (with options) to answer.
While deer may be found in many varied locations, they mostly make their home | [
"in densely covered wilderness",
"outside of grassy areas",
"in largely populated parks",
"near cabins in small towns"
] | A | a deer lives in a forest |
OpenBookQA | OpenBookQA-809 | 3. Jun 16, 2009
### HallsofIvy
Writing "M" for male and "F" for female, there are 25= 32 ways to write 5 letters, each being either an "M" or an "F". Of those 32, exactly one is all "M"s and exactly one is all "F"s.
Knowing that there is at least one female drops "MMMMM" leaving 31 possibilities. "FFFFF" is one of those: probability 1/31.
If we write the dogs in order of age, then knowing that the oldest dog is female means that we are looking at lists of 5 letters, from "M" or "F", with the first letter being "F". Obviously in all possible lists of 5 "M"s or "F"s, exactly half, 16 start with "F" and half with "M" so knowing that "the oldest dog is a female" throws out half the possible lists, leaving 16. one of those is "FFFFF" so the probability of "all females" is now 1/16.
There is no "dilemma" here. "The oldest dog is female" gives you more information than "at least one of the dogs is female".
4. Jun 16, 2009
### fleem
First breeder:
Since its given that there is at least one female, the question, "what is the probability that all five are female when one is female" means the same thing as the question, "What is the probability that the remaining four are female". The probability that the remaining four are female is 1/16, and thus the probability that all five are female (given that one is female) is 1/16.
Second breeder:
The temptation here is to assume there might have been intelligent pre-selection of dogs in the group, by the store owner. However the OP makes it pretty clear, I think, that there was no such pre-selection, and that these are ALL the dogs from a given litter. So the sex of a randomly selected dog does NOT change the probability of the sex of another dog in the litter. Each is a separate coin toss. So the fact that the oldest is female works the same as "there is at least one female". So like with the first breeder case, the probability of the remaining four all being female is 1/16.
5. Jun 16, 2009
The following is multiple choice question (with options) to answer.
An animal can use what to help find a partner | [
"social networking and dating apps",
"beautiful vibrant tail plumage",
"asking animal friends for advice",
"meet ups and social gatherings"
] | B | coloration is used to find a mate by some animals |
OpenBookQA | OpenBookQA-810 | 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.
Where could you find organic matter? | [
"plastic items",
"carbon dioxide",
"a rabbit",
"table salt"
] | C | an organism is a source of organic matter |
OpenBookQA | OpenBookQA-811 | zoology, ecology, diet, predation
Cheetahs have been reported to suffer from intraguild competition by lions Panthera leo, spotted hyenas Crocuta crocuta and occasionally leopards Panthera pardus. These larger predators represent a threat to the smaller-bodied cheetahs as they can affect their food intake by limiting access to high resource areas or kleptoparasitism (e.g. 10–12% of kills are kleptoparasitized in Serengeti National Park (SNP)), and reduce population sizes via increased cub mortality (e.g. 73% of cub mortality was due to predation in the SNP). In response, cheetahs often demonstrate avoidance behavior to minimize interactions with dominant carnivores , with spatial and temporal partitioning regarded as the principal behavioral mechanisms by which this is achieved. Accordingly, cheetahs have been described as a refugial species that seeks competition refuges within the landscape with low densities of lions and spotted hyenas.
Rostro-García S, Kamler JF, Hunter LT. To kill, stay or flee: the effects of lions and landscape factors on habitat and kill site selection of cheetahs in South Africa. PLoS One. 2015;10(2):e0117743. Published 2015 Feb 18. doi:10.1371/journal.pone.0117743
(removed the citations)
The definition of the terms used in the above citation:
Intraguild predation, or IGP, is the killing and sometimes eating of a potential competitor of a different species. This interaction represents a combination of predation and competition, because both species rely on the same prey resources and also benefit from preying upon one another. - Wikipedia
Kleptoparasitism, literally meaning parasitism by theft, is a form of resource acquisition where one animal takes resources from another. Although kleptoparasitism of food (i.e., kleptoparasitic foraging) is the best known example, the stolen resources may be food or another resource such as nesting materials. - Sciencedirect.com
The following is multiple choice question (with options) to answer.
Competition is fierce among lions | [
"when new prey species arrive in the community",
"when population of lions decreases",
"when there are a plethora of prey choices",
"when the antelopes are scare"
] | D | as the population of prey decreases , competition between predators will increase |
OpenBookQA | OpenBookQA-812 | species-identification, botany, ecology
Title: Algae or Lichen identification. Coastal BC, Canada I have tried all books and internet resources I know of, but I still have no idea what this might be — a lichen or something else.
At first glimpse, I thought it was something man-made and unnatural, but then I looked closer and saw how it appears to be attached and growing. It grows on exposed rocks well above the high tide. The photo is taken in late March, on northern Vancouver Island. It's loosely attached to the rock.
It was somewhat abundant around the general area (within of a few km), but I haven't seen it elsewhere - although I'm not from BC so there might be a lot of this around.
The water droplet in the lower right corner give a rough sense of scale.
Edit:
Adding another photo in which I just noticed a streak of white, which I included in original resolution. I want to propose you expand your search to a broader taxonomic scope. Specifically, I think you might be looking at a species of "red" green algae (family: Trentepohliaceae).
From Nelson et al. (2011):
All Trentepohliaceae have filamentous growth forms and often contain large amounts of carotenoid pigments (ß-carotene and hematochrome), causing the algae to appear yellow orange in color (Thompson and Wujek 1997, Lo´pez-Bautista et al. 2002).
The Trentepohliaceae contains five genera: (Trentepohlia, Printzina, Phycopeltis, Cephaleuros and Stomatochroon) and 70+ species worldwide.
For example, the following algae (picture from England) looks fairly similar to your specimen:
Trentepohlia aurea
Source: David Fenwick
If your specimen is a species in this family of algae, it is most likely in the Trentepohlia genus (or possibly Printzina genus).
Trentepohlia is a genus of filamentous chlorophyte green algae in the family Trentepohliaceae.
Typically orange or yellow in color.
Live on tree trunks and wet rocks or symbiotically in lichens.
Here's a picture of a free-living Trentepohlia species from coastal Oregon, USA:
Source: Richard C. Hoyer (2015)
The following is multiple choice question (with options) to answer.
Algae perform photosynthesis and so they are like to be found where in a body of water? | [
"nowhere",
"bottom",
"top",
"middle"
] | C | algae is found in bodies of water |
OpenBookQA | OpenBookQA-813 | That would be a total of 5x30 + 3x40 + 2x60 = 390 plants (with an arbitrary factor that we'll set to 1 without loss of generality).
The amount of highbush is 5x30 = 150.
The amount of lowbush is 3x40 = 120.
The amount of hybrid is 2x60 = 120.
If the opossums didn't care, they would likely eat blueberries in this ratio (null hypothesis H0).
The total that we have observed the opossums to eat is 5% x 150 + 10% x 120 + 20% x 120 = 43.5 plants.
They eat 5% large, which a corresponding fraction of 5% x 150 / (5% x 150 + 10% x 120 + 20% x 120) = 17%
They eat 10% low for 10% x 120 / (5% x 150 + 10% x 120 + 20% x 120) = 28%
They eat 20% hybrid for 20% x 120 / (5% x 150 + 10% x 120 + 20% x 120) = 55%.
Checking... yes the total is 100%.
What we see is that the opossums prefer hybrid by far.
Small blueberries are their second choice.
Last edited:
#### anemone
##### MHB POTW Director
Staff member
Hi anemone!
What do you mean by the symbol E?
Anyway, you've found that the opossums eat 45.8% large and 54.2% small for a total of 100%.
But... what happened to the hybrid blueberries?
By the symbol E, I meant the blueberries (all 3 types of them) that are eaten by opossums...
That would be a total of 5x30 + 3x40 + 2x60 = 390 plants (with an arbitrary factor that we'll set to 1 without loss of generality).
The amount of highbush is 5x30 = 150.
The amount of lowbush is 3x40 = 120.
The amount of hybrid is 2x60 = 120.
If the opossums didn't care, they would likely eat blueberries in this ratio (null hypothesis H0).
The following is multiple choice question (with options) to answer.
Meadow voles consume | [
"producers",
"apex predators",
"decomposers",
"detritivores"
] | A | meadow voles eat plants |
OpenBookQA | OpenBookQA-814 | electrostatics, electricity, electric-current, charge, flow
Title: Why does the flow of charge even create electricity? Okay this is a question I’ve asked a lot of places but I always get its the flow of charges and it’s like a property. What I don’t really understand is how is this flow of charges creating electric current.
My guess is that as these charges get closer to the desired potential(to satisfy potential difference) Energy is released which happens continuously and it is the reason for electric current atleast in a conductor.
Can I get some insight into what is happening down at the quantum level. First of all you have to understand that flow of electrical current and dissipation of energy are two completely different concepts.
Electrical current: The flow of electrical charges is called electrical current. This is like a definition and has nothing to do with dissipation. There are systems, where current flows without dissipation. At the elementary level, you get the electrical current $I$, if you count, how many elementary charges $e$ cross a specific cross-sectional area of your "conductor" per second. Mathematically this means:
$$ I := \frac{e\Delta N}{\Delta t},$$
where $I$ is the current, $\Delta t$ is the time interval (e.g. 1 second), $e$ is the elementary charge, and $\Delta N$ is the number of elementary charges that you count within time $\Delta t$.
Usually, conductors are metals, and you may think of the cross sectional area of a copper wire, for example. But you can also imagine other "conductors" that are liquids with ions in them, or even gases with charged atoms in them.
Electrical resistance: Flowing charge carriers dissipate energy, if they scatter with other particles and thereby lose energy. In metals, for example, electrons forming the electrical current will scatter from lattice vibrations (phonons) and thereby dissipate energy. This energy dissipation leads to electrical resistance, usually denoted by $R$.
The following is multiple choice question (with options) to answer.
How can it be shown that an electrical conductor is a vehicle for the flow of electricity? | [
"holding an electrified fence can kill you",
"electricity is unable to conduct well through rubber shoe soles",
"sticking a fork into an electrical outlet is safe if it is plastic",
"electricity is a volatile thing"
] | A | An electrical conductor is a vehicle for the flow of electricity |
OpenBookQA | OpenBookQA-815 | “It’s amazing, given the billions of hours humans spend in the water, how uncommon attacks are,” Burgess said, “but that doesn’t make you feel better if you’re one of them.” (Source here.)
18.9% of NC visitors went to the beach (source) . In 2012, there were approximately 45.4 million visitors to NC (source). To overestimate the number of beachgoers, Let’s say 19% of 46 million visitors, or 8.7 million people, went to NC beaches. Seriously underestimating the number of beachgoers who enter the ocean, assume only 1 in 8 beachgoers entered the ocean. That’s still a very small 7 attacks out of 1 million people in the ocean. Because beachgoers almost always enter the ocean at some point (in my experiences), the average likely is much closer to 2 or fewer attacks per million.
To put that in perspective, 110,406 people were injured in car accidents in 2012 in NC (source). The probability of getting injured driving to the beach is many orders of magnitude larger than the likelihood of ever being attacked by a shark.
Alison Kosik should keep up her surfing.
If you made it to a NC beach safely, enjoy the swim. It’s safer than your trip there was or your trip home is going to be. But even those trips are reasonably safe.
I certainly am not diminishing the anguish of accident victims (shark, auto, or otherwise), but accidents happen. But don’t make too much of one either. Be intelligent, be reasonable, and enjoy life.
In the end, I hope my students learn to question facts and probabilities. I hope they always question “How reasonable is what I’m being told?”
Here’s a much more balanced article on shark attacks from NPR:
Don’t Blame the Sharks For ‘Perfect Storm’ of Attacks In North Carolina.
Book suggestions:
1) Innumeracy, John Allen Paulos
2) Predictably Irrational, Dan Ariely
CAS and Normal Probability Distributions
My presentation this past Saturday at the 2015 T^3 International Conference in Dallas, TX was on the underappreciated applicability of CAS to statistics. This post shares some of what I shared there from my first year teaching AP Statistics.
MOVING PAST OUTDATED PEDAGOGY
The following is multiple choice question (with options) to answer.
Sandbars are a part of most seas because there are | [
"waves which adjust silt",
"lots of stones in seas",
"places where fish eat",
"sand that needs to be piled"
] | A | a sandbar is formed by water moving sediment downstream |
OpenBookQA | OpenBookQA-816 | biochemistry, botany, plant-physiology, photosynthesis
What are typical characteristics of different plants in this regard? I.e., how do common species of plants manage their C consumption before (and after) the development of leaves? There are quite a few questions and thoughts in there, I'll try to cover them all:
First, to correct your initial word equation: During photosynthesis, a plant translates CO2 and water into O2 and carbon compounds using energy from light (photons).
You are correct to assume the C is further used for the growing process; it is used to make sugars which store energy in their bonds. That energy is then released when required to power other reactions, which is how a plant lives and grows. C is also incorporated into all the organic molecules in the plant.
Plants require several things to live: CO2, light, water and minerals. If any of those things is missing for a sustained period, growth will suffer. Most molecules in a plant require some carbon, which comes originally from CO2, and also an assortment of other elements which come from the mineral nutrients in the soil. So the plant is completely reliant on minerals.
Most plants, before a leaf is established or roots develop, grow using energy and nutrients stored in the endosperm and cotyledons of the seed. I whipped up a rough diagram below. Cotyledons are primitive leaves inside the seed. The endosperm is a starchy tissue used only for storage of nutrients and energy. The radicle is the juvenile root. The embryo is the baby plant.
The following is multiple choice question (with options) to answer.
Which is needed for photosynthesis to occur | [
"chemical with the atomic number 18",
"energy that takes 8.3 minutes to travel to Earth",
"the 8th entry on the periodic table",
"the most prevalent chemical in the atmosphere"
] | B | photosynthesis means green plants convert from carbon dioxide, water, and solar energy into oxygen for themselves |
OpenBookQA | OpenBookQA-817 | Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4675
Re: The harvest yield from a certain apple orchard was 350 bushels of appl [#permalink]
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AbdurRakib wrote:
The harvest yield from a certain apple orchard was 350 bushels of apples. If x of the trees in the orchard each yielded 10 bushel of apples, what fraction of the harvest yield was from these x trees?
A) $$\frac{x}{35}$$
B) 1–($$\frac{x}{35}$$)
C) 10x
D) 35–x
E) 350–10x
OG 2017 New Question
Dear AbdurRakib,
I'm happy to respond. This kind of word problem intimidates many people, but the actual calculation here is quite straightforward.
A fraction is a part over a whole. The whole is 350 bushels.
Of this set of x special trees, special for some unknown reason, each tree produced 10 bushels. That's 10x bushels from the lot of them. That's the part.
fraction = $$\frac{10x}{350}$$ = $$\frac{x}{35}$$
Does this make sense?
Mike
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Re: The harvest yield from a certain apple orchard was 350 bushels of appl [#permalink]
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15 Jun 2016, 00:41
Total yield by x trees = 10x
So, fraction of the harvest yield from these x trees = 10x/350 = x/35
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Re: The harvest yield from a certain apple orchard was 350 bushels of appl [#permalink]
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27 Jul 2016, 10:52
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Here are a couple of ways to solve this question:
Value Substitution:
Algebra:
The following is multiple choice question (with options) to answer.
When trees are harvested, the trees | [
"are lacking in leaves",
"need to be replaced or numbers go down",
"are tiny and irrelevant",
"are smaller and less"
] | B | cutting down trees in a forest causes the number of trees to decrease in that forest |
OpenBookQA | OpenBookQA-818 | # Physics kinematics SIN question
1. Dec 30, 2011
### ShearonR
1. The problem statement, all variables and given/known data
A car, travelling at a constant speed of 30m/s along a straight road, passes a police car parked at the side of the road. At the instant the speeding car passes the police car, the police car starts to accelerate in the same direction as the speeding car. What is the speed of the police car at the instant is overtakes the other car?
Given: v=30m/s
vi=0
Need: vf=?
2. Relevant equations
vf=vi+αΔt
vf2=vi2+2αΔd
v=Δd/Δt
3. The attempt at a solution
So far, I really have not gotten anywhere. I believe what I have to do is somehow manipulate the velocity equation of the first car into something I can input into the vf equation for the police car. I have been having much trouble with this question and would appreciate any tips to point me in the right direction.
2. Dec 30, 2011
### Vorde
This isn't solvable without knowing the acceleration of the police car, without it the velocity when the police car overtakes the other car could be anything.
edit: You don't necessarily need the acceleration, but you need at least one other piece of information (such as at what distance did the police car overtake the other car) to solve the problem.
3. Dec 30, 2011
### ShearonR
Yes, and that is what I have been fretting over this whole time. They give multiple choice answers, but essentially they all work. I know that depending on the magnitude of the displacement or the time, the rate of acceleration will change.
4. Dec 30, 2011
### Staff: Mentor
Interesting. I think I was able to solve it just with the given information (unless I did something wrong). Pretty simple answer too.
You should write an equation that equates the distance travelled to the meeting/passing spot for each car (call that distance D). The speeding car's velocity is constant, so what is the equation for the time it takes for the speeding car to get to D?
The following is multiple choice question (with options) to answer.
A cop can tell that a car is speeding because it is | [
"cruising quickly",
"driving along",
"moving forward",
"on the road"
] | A | speed is a measure of how fast an object is moving |
OpenBookQA | OpenBookQA-819 | anatomy, scales
If this horse is 500 kg (a mid-range mass for horses), each leg would have to support 125 kg, compared to only 37.5 kg for a 75 kg adult. Why don't we see a corresponding difference in cross-section? Elephant, rhinoceros, &c all have much thicker legs in proportion. The answer, I think, lies in the fact that the animals you mention all evolved as cursorial animals (that is, they run to escape predators). Less mass in the lower leg means it swings easier, so the animal can run faster.
There are two things you're apparently not noticing in that picture. First, the the horse's lower leg is almost entirely bone (and some tendon), and it's bone that does the supporting. The propulsive power comes from the large muscles of the hip, thighs, and shoulders.
Second, the lower part of the leg (with the white wrappings) is not anatomically equivalent to the human's lower leg, but to the bones of the hand and foot. You can see this if you look closely at the rear leg in that picture. The femur, equivalent to the human's thigh, ends at the knee just above the belly line. Then the tibia extends about halfway down, ending at another joint which you might think is the knee, but which is called the 'hock' in horse-speak. The white-wrapped part is a metatarsal, equivalent to human foot bones, then there pastern bones equivalent to human toe bones, ending in the hoof/toenail.
So consider that you can, if reasonably fit, walk around on tiptoe without crushing your foot and toe bones, then imagine the end result of your ancestors having done this for the last several tens of millions of years :-)
PS: With horses, there is some effect from human selection, too. Racing & show breeds tend to have thin lower legs, draft horses & working breeds have proportionately thicker ones. My first horse, a thorobred/arab mix, had legs about as thick as my wrists (granted, I'm a fairly muscular guy); my current mustang, about the same height & weight, has legs about twice as thick.
The following is multiple choice question (with options) to answer.
A herd of wild horses has been decreasing in size rapidly. Which of these might be the cause? | [
"There has been a lot of rain",
"The month of July has arrived",
"Predators have moved out of the area",
"All of the vegetation has been dying"
] | D | the ability to find resources has a positive impact on an organism 's survival |
OpenBookQA | OpenBookQA-820 | experimental-physics, mass, buoyancy, fluid-statics, gas
Title: How can I determine whether balloons inside a balloon are filled with the same gas? We recently awarded ourselves some helium balloons to celebrate something, and they came with about a dozen little balloons inside, filling it to just under half way.
I was discussing with a colleague whether it would be possible to determine whether the inner balloons were also helium-filled, without popping the large outer balloon.
Obviously, if the inner balloons were filled with something moderately lighter than helium, they would float, but they're huddled at the bottom, so it's either helium or plain air.
How about it?
p.s. you guys really need a 'balloon' tag. :) One indication whether the 'inner' balloons are filled with helium or something heavier is whether the 'outer' balloon still floats in air or not.
Whether it floats or not depends on whether its overall density is lower than air's density or not. Its overall density $d$ is simply given by:
$$d=\frac{\Sigma m}{V}$$
Where $\Sigma m$ is the sum of all the masses that make up the balloon and $V$ its total volume.
The sum of all masses means the sum of:
Mass of outer balloon material
Mass of helium
Masses of all inner balloons material
Masses of all gas contained in the inner balloons
If the inner balloons are filled with air and there are too many of them the overall density will exceed that of air and the outer balloon will not float.
But even if the inner balloons are all filled with helium, the outer balloon may still not float. That's because a larger number of inner balloons making up the same volume of a smaller number of inner balloons with create more mass because of the increased surface area and the inherent 'cost' in mass of larger number of inner balloons. For that reason:
Obviously, if the inner balloons were filled with something moderately lighter than helium, they would float, but they're huddled at the bottom, so it's either helium or plain air.
The following is multiple choice question (with options) to answer.
how come a person can blow into a balloon and use the same air to fill a soccer ball? | [
"it is the law of thermodynamics",
"it is the ability of it to conform",
"it is a shift in the cosmos",
"all of these"
] | B | Matter in the gas phase has variable shape |
OpenBookQA | OpenBookQA-821 | vacuum, space
Title: What causes an atom to move to a vacuum? Im in no way an expert in physics but I've been thinking about this for a while.
What force makes something move to a vacuum?
For example imagine shooting some ice cream into space (lets say it doesnt get burnt up) I'd imagine all the air will get sucked out of it, but why? In the simplest case, consider an open jar of air. The atoms move around randomly, and in fact exchange with atoms from the air around. When the jar is put in the vacuum the atoms that leave are not replaced (well almost never) so the number in the jar drops quickly. This effect is made a lot stronger by the fact that in the air, the atoms trying to leave the jar are hit by incoming atoms and knocked back in (sometimes) but in the vacuum they are almost never knocked back.
The details of a fluid evaporating are complicated by surface tension and so on. But this shows that basic point. In air there are atoms constantly colliding with the object keeping it compact. But in a vacuum these atoms are not there and the object has a greater tendency to expand.
Also, remember that the actual motion due to heat is very high but random. The potential is for the hot atoms at the surface to head off at the thermal velocity. Very rapid.
The following is multiple choice question (with options) to answer.
A product of what can travel through a vacuum? | [
"Rigel",
"oil well",
"volcano",
"iceberg"
] | A | light can travel through a vacuum |
OpenBookQA | OpenBookQA-822 | temperature, measurements
Title: Are average daily temperatures affected by DST? To calculate the average daily temperatures, do meteo professionals still use the Mannheim procedure with twice weighted measurement in the evening? (It could be obsolete by automated weather stations.)
If so, does DST affect the daily average by getting that measurement one hour earlier?
I'm not asking if that invalidates the results, just whether there is a measurable impact. They compensate for DST.
That is, for any daily measurement, they use the same universal time every day of the year. If they take a measurement at 7:00 local time in summer, they will take the same measurement at 6:00 in winter.
(So if you do see a DST effect in the data, that would be due to traffic and other local anthropogenic effects shifting by an hour relative to the time of measurement! Perhaps due to urban heat island effect, or forcing by anthropogenic aerosols from traffic or industry.)
The following is multiple choice question (with options) to answer.
What needs measurements taken in the morning and evening? | [
"coastal range",
"tidal range",
"wave length",
"apex"
] | B | tidal range is a measure of the vertical distance from high tide to low tide |
OpenBookQA | OpenBookQA-823 | 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.
A field is experiencing above average rainfall and food is plentiful, so the rabbits living there will | [
"produce larger litters",
"find new land",
"die much younger",
"eat less food"
] | A | as available resources increases , the population of an organism that uses those resources will increase |
OpenBookQA | OpenBookQA-824 | zoology, ornithology, ethology, behaviour
Title: Crow branch pecking behaviour I was walking through a small park when two crows started cawing at me, and followed me, flying from tree-to-tree as I walked. I speculate that this is a territorial or protective behaviour, but what I found different was the crows were violently pecking the branches nearby them. I have no memories coming to mind of seeing this behaviour beforehand. I speculate that this behaviour could be threat displays, but a quick search on Google did not reveal to me any authoritative studies on this phenomenon. I'd appreciate more information and sources.
This question has been added as a casual observation on iNaturalist. This is a good question. This type of behavior -- pecking at a branch, wiping the side of the beak on a branch, pulling off twigs and dropping them, or knocking off pieces of bark -- is quite common among many corvid species, particularly when they are interrupted by something or someone that they might consider a threat. This includes not only potential predators but also potentially hostile conspecifics.
It is typically considered to be a form of displacement behavior. The concept of displacement behavior, from classical ethology, posits that when an animal experiences two conflicting drives to do two different things, it doesn't know which to do and does a third thing instead to dissipate the drive or anxiety. For branch-pecking in crows, see E.g Kilham and Waltermire 1990 Ch. 12.
Referece: Kilham, L., & Waltermire, J. (1990). The American crow and the common raven. Texas A&M University Press.
The following is multiple choice question (with options) to answer.
a wren building a home is an example of what type of behavior | [
"good",
"inherited",
"learned",
"bad"
] | B | An example of an inherited behavior is a bird building a nest |
OpenBookQA | OpenBookQA-825 | botany, plant-physiology, plant-anatomy
*No others are known, but could definitely exist.
Bibliography
Crafts, A. S. “Phloem Anatomy, Exudation, and Transport of Organic Nutrients in Cucurbits.” Plant Physiology 7, no. 2 (1932): 183–225.
Fischer, A. “Das Siebröhrensystem von Cucurbita.” Berichte Deutsche Botanische Gesell 1 (1883): 276–279.
Fischer, A. “Neue Beiträge Zur Kenntniss Der Siebröhren.” Berichte Über Die Verhandlungen Der Königlich-Sächsischen Gesellschaft Der Wissenschaften Zu Leipzig, Mathematisch-Physische Klasse 38 (1886): 291–336.
Fischer, A. Untersuchungen Über Das Siebröhren System Der Cucurbitaceen. Berlin, 1884.
Turgeon, R. and Oparka, K. “The Secret Phloem of Pumpkins.” Proceedings of the National Academy of Sciences 107, no. 30 (2010): 13201 –13202.
Walz, C. and Giavalisco, P. and Schad, M. and Juenger, M. and Klose, J. and Kehr, J. “Proteomics of Curcurbit Phloem Exudate Reveals a Network of Defence Proteins.” Phytochemistry 65, no. 12 (2004): 1795–1804.
Zhang, B. and Tolstikov, V. and Turnbull, C. and Hicks, L. M. and Fiehn, O. “Divergent Metabolome and Proteome Suggest Functional Independence of Dual Phloem Transport Systems in Cucurbits.” Proceedings of the National Academy of Sciences 107, no. 30 (2010): 13532.
The following is multiple choice question (with options) to answer.
Phloem | [
"acts as a delivery person for a plant",
"acts as a trainer for a plant",
"acts as a doctor for a plant",
"acts as a farmer for a plant"
] | A | phloem transports materials through the plant |
OpenBookQA | OpenBookQA-826 | everyday-life
Title: Strange pattern on car windows
A couple of days ago I was in a friend's car, and I noticed this pattern on the windows; I took a picture of the sun through the window to make it clearly visible.
The night before had been quite cold, but I don't think that the temperature went below $0$ °C, even though I am sure that it did some days before.
I can speculate that the phenomenon originated from some condensation/freezing of humidity on the outside of the car window, so I searched the web for pictures of water condensation and frost patterns (and also water staining) on car windows, but couldn't find anything similar.
What could be the origin of this intricate pattern? From your question, I can guess that the weather is rainy in your region.
When you drive a car in the rain, the water drops pass your windows at an angle. This, plus wind and other winter stuff causes the path of the drops to twist and jiggle like in this photo
I would also guess that the rain stopped while still driving, so the water could've evaporated in this pattern. The sunlight then makes those residues more pronounced when you took the picture.
Take a look at the following picture from a google search of 'water stains on glass'. To me it looks similar to your photo, just without the effect of moving window (keep in mind that the residues in the water may differ from one place to another due to pollution and etc., so the stains don't have to look the same).
The following is multiple choice question (with options) to answer.
Rain pours on a road for a night, then freezes in the morning, so what happens to the road? | [
"begins to crack",
"begins to swell",
"begins to slide",
"begins to crumble"
] | A | when water freezes , that water expands |
OpenBookQA | OpenBookQA-827 | behaviour, language, genetic-code
Title: How does DNA encode high level features like animal behaviour and language? We know there are complex features which animals supposed to develop based on their genes as opposed to learning from the environment and the collective, also sometimes being very specific to certain species:
Concepts how to build homes
Animal languages including social insect interactions responsible for information transmission (or do they have to learn them through an acquisition process, let's exclude languages of ape tribes where "term" creation has been demonstrated?)
Valid answer: if already known, one or to examples to corresponding research.
Constraint: we are not talking about genes responsible for some sort of tendencies in behaviour but situations where there seems to be a more or less complex "blue print". I suppose we are yet very far from understanding these things. Relation of genotype to phenotype is teh subject of much contemporary research, but it is mainly limited to simple phenotypic features, explainable by action of a few genes, such as the colors of zebra fish mutants: see, e.g., this paper and the related publications by Nüsseln-Vollhardt group. Perhaps closer to your question is circadian rythms, which also have genetic determinants.
The complex behaviors are likely a result of the complex interactions of many genes, which are a very interesting, but also a very difficult problem to solve.
The following is multiple choice question (with options) to answer.
Why do zebras choose to live where they live? | [
"great location",
"lovely view",
"edible items",
"good parking"
] | C | animals live and feed near their habitats |
OpenBookQA | OpenBookQA-828 | roslaunch
I do not know if I should give you now the concrete solution. Perhaps you can try it on your own after this explaining and if you have further problems we can talk about it.
Didnt mentioned or checked the correctness of mimic by now. We talk abut this later too.
The following is multiple choice question (with options) to answer.
which of these can alter its appearance naturally to evade being captured? | [
"a little chameleon",
"a human being",
"a lion",
"a goat"
] | A | An example of camouflage is an organism looking like leaves |
OpenBookQA | OpenBookQA-829 | quantum-mechanics, soft-question, popular-science
The situation here is uncertain because of issues far displaced from chaos or quantum. The challenges arise because it is massively difficult to isolate the input factors and determine them.
School performance, for example, could esily be expected to be influenced by many different inputs. Family patterns, income, culture, etc. etc. It would be a chore to even list them all, never mind determine them and extract the effect. Thus, supposing there is an effect due to nutrition, it may be required to extract the effect from the effect of large numbers of other input factors. Each of which may be known to a different degree of accuracy.
This school uses this set of textbooks and that another set. It already begins to be difficult to extract results. This school runs for 7 hours per day and that one 9. This one starts students at age 6 and that at age 5. And so on and so on. This one is in the innner city and that one is far out in rural areas. All of these could easily be expected to have some effect, though in advance it would be difficult to know exactly what.
And it is also massively difficult to be confident in the output factors. It may be that different school systems do things very differently and so performance is a major challenge to extract and compare. This school uses numerical grades and that letter grades is just a trivial example. This school uses standardized state-wide tests, this one uses surprise quizzes, and that one uses interviews of the students. This one does a lot of written work with written tests, and that one does a lot of hands-on work with group presentations. It is a challenge to extract the results and present them in a manner that fairly compares them. Sometimes even for the same school from one year to the next.
And, even when two schools use the same method of evaluating performance, it is not instantly obvious that this method is a good predictor of the academic future of a given student. Written tests, for example, can be well correlated on average. But the individual student is subject to a huge collection of factors that may mean he does not align with the results his tests would suggest.
The following is multiple choice question (with options) to answer.
School children often play a musical instrument by | [
"sweeping thumb across elastic band over a beverage carton",
"making rubber band chain bracelets",
"wearing rubber bands with braces",
"shooting rubber band with one hand"
] | A | An example of playing a musical instrument is strumming a guitar string |
OpenBookQA | OpenBookQA-830 | 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.
Adding force to a moving train will: | [
"cause it to travel further in the same time",
"cause the structure to take up less space",
"cause it to travel less distance in the same time",
"increase the mass of the structure"
] | A | force causes the speed of an object to increase |
OpenBookQA | OpenBookQA-831 | radiation
Title: Other methods of X-ray production Long running debate, I would like to find a definitive answer.
In a long glass tube (borosilicate or other common glass) with high frequency AC excitation at one end, 50-60kV, with high evacuation, I see a pale green glow in the glass. Some people claim this is due to X-ray production when the electrons collide with the glass. Others claim this is "cathode rays" being produced. My understanding of "Cathode rays" is that this is an old term for electrons moving through the vacuum.
I have seen youtube videos showing increased counts on a radiation detector, but I know that this could be faked or due to other effects.
https://www.youtube.com/watch?v=af8wnm2eGWw
I've seen the classic description of how X-ray tubes work, but I am wondering if this is another method of generating X-rays, probably far less efficient than the metal target. Interesting video. Yes I'm pretty sure this is a method for generating X rays. In fact, before the invention of the Coolidge tube (incandescent tungsten cathode filament which allowed independent control of voltage and current) all X-ray tubes were a variant of this: they had a pointy cathode, a flat (stationary) anode, and a small amount of gas. When HV was applied (usually AC since that is easier to generate), the gas at the cathode tip would ionize, causing electrons to be accelerated to the anode. During the acceleration, the electrons would continue to ionize gas, and ions would start to flow to the cathode. These ions would bombard (heat) the cathode, increasing the electron emission further. Problem with this design: for a given value of HV and gas pressure, the current was "what it was". So the radiologist would put his hand in the beam to see if he got a good shadow on the phosphor screen. If not, then he would get out the Bunsen burner and heat a small amount of asbestos that was kept inside a small tube off the main bulb. The hot asbestos would out gas, and raise the pressure in the tube. Soon it would work at peak efficiency again...
The following is multiple choice question (with options) to answer.
What can be produced when electrical energy is provided to a blown piece of glass with a wire inside? | [
"luminescence",
"lifeforce",
"sound",
"Water"
] | A | a light bulb requires electrical energy to produce light |
OpenBookQA | OpenBookQA-832 | zoology, ethology, behaviour, psychology, death
Title: Do animals suffer from "Human" mental disorders? It is tragic, but apparently Killer whales and Dolphins can commit suicide too (e.g. here)...
This suggests they can become depressed. I wondered whether they were "clinically" depressed like many people are, and what other mental illnesses have been observed in animals in general.
Questions
Which mental disorders have been observed in animals? Which animals?
What is the prevalence of these mental disorders in those animals?
Are the causes and treatments of these disorders similar to Humans?
The following is multiple choice question (with options) to answer.
Given that animals are generally unfriendly with humans and would prefer their own space, which of these creatures is an anomaly? | [
"buffalo",
"deer",
"scottish folds",
"boar"
] | C | animals usually distance themselves from humans |
OpenBookQA | OpenBookQA-833 | pressure, fluid-statics, atmospheric-science, buoyancy, gas
Title: Math behind helium balloons lifting objects to (almost) space So I've seen those big helium balloons that are not even filled all the way up, but they still manage to reach heights of up to 30 km. I think they're mainly used for research and etc. Furthermore, I also have noticed that because of the lower pressure higher in the atmosphere helium expands and balloon seems filled up. How do you actually find maximum volume of the balloon according to the height that it has to reach and temperature at that height? And how much helium do you need according to the mass that the balloon has to carry? Take a look at the ideal gas law and Archimedes' principle.
How do you actually find maximum volume of the balloon according to the height that it has to reach and temperature at that height?
The ideal gas law describes how the volume of a gas varies with amount, in mol, of gas particles, pressure, and temperature. You should be able to calculate the volume of helium at high and low altitudes by searching for the pressures and temperatures at those locations. Note that the gas pressure is of the helium in the balloon. This is only slightly larger than the surrounding air (atmospheric) pressure due to any surface tension in the balloon, so we can take the two to be roughly equal.
And how much helium do you need according to the mass that the balloon has to carry?
Archimedes' principle allows you to calculate the upthrust on an object in a fluid (a liquid or gas).
The upthrust is determined by the volume of the object (in this case the volume of the air balloon), and the density of the fluid (here the density of the air at different altitudes).
In order for the balloon to be able to float, the upthrust must be at least as large as the weight of the balloon (the combined mass of the gas and the load).
The following is multiple choice question (with options) to answer.
How can things that are very tall have things lifted up them? | [
"a kite is flown with a string attached",
"a string that loops from top to bottom",
"flats are flown to the top of poles",
"a flagpole is leaned down to get a flag on it"
] | B | a pulley is used to lift a flag on a flagpole |
OpenBookQA | OpenBookQA-834 | food, nutrition
Supplements aren't intended to be a food substitute because they can't replicate all of the nutrients and benefits of whole foods, such as fruits and vegetables.
and there are three main differences:
Greater nutrition. Whole foods are complex, containing a variety of
the micronutrients your body needs — not just one. An orange, for
example, provides vitamin C plus some beta carotene, calcium and
other nutrients. It's likely these compounds work together to produce
their beneficial effect.
Essential fiber. Whole foods, such as whole grains, fruits,
vegetables and legumes, provide dietary fiber. Most high-fiber foods
are also packed with other essential nutrients. Fiber, as part of a
healthy diet, can help prevent certain diseases, such as type 2
diabetes and heart disease, and it can also help manage constipation.
Protective substances. Whole foods contain other substances important
for good health. Fruits and vegetables, for example, contain
naturally occurring substances called phytochemicals, which may help
protect you against cancer, heart disease, diabetes and high blood
pressure. Many are also good sources of antioxidants — substances
that slow down oxidation, a natural process that leads to cell and
tissue damage.
So you could live off of some meal replacement shake for the rest of your life but should you? Probably not.
The following is multiple choice question (with options) to answer.
A person will need to eat fruits and vegetables in order to have a healthy life and body, so other humans must | [
"tend produce",
"eat chips",
"buy bagels",
"make fields flood"
] | A | humans eat crops |
OpenBookQA | OpenBookQA-835 | thermodynamics, physical-chemistry, combustion
Title: Is there an 'intuitive' explanation for "Which burns more?" In helping a friend's son with his grade 10 science homework, I came across a question that essentially asked the following:
"If two objects of equal mass but different specific heat capacities are touched, which will burn more?"
The wording of the question implied that this was meant to be a thought experiment rather than anything calculation-based.
My first reaction was that this question was probably quite a bit more complex than it was made out to be; a quick search online and on this site confirms this, however ideas like conductivity (which I'm familiar with), diffusivity & effusivity (which I'm not) and others are well beyond the student's understanding at the moment. I also felt "burn more" was rather vague.
To address these concerns, I made the following two assumptions:
since the question made no reference to time, I took the phrase "burn more" to mean "transfer the most energy by the time equilibrium has been reached"
all parameters like mass (mentioned in the question), density, conductivity, area of contact, etc., other than specific heat capacity and time would be equal.
The following is multiple choice question (with options) to answer.
What would be easier to burn? | [
"A park bench",
"A silver spoon",
"Tupperware",
"An Airplane"
] | A | dry wood easily burns |
OpenBookQA | OpenBookQA-836 | civil-engineering
Other things that can be done is to place hay bales, or rocks, on the soil slope and on the slope above the deposited soil. These can help to reduce the speed of surface water running down the slope.
If hay bales are used they should be placed in a staggered, off-set pattern, so that long drainage channels, which would lead to the formation of erosion gullies, are not created by the bales.
Moonscaping of the upper natural slope, above the deposited soil slope would also help in preserving the deposited soil slope.
The following is multiple choice question (with options) to answer.
Why animal may use a rock as shelter | [
"Centipede",
"Dolphin",
"Seagull",
"Dog"
] | A | rocks are a source of shelter for small animals in an environment |
OpenBookQA | OpenBookQA-837 | zoology, entomology
Title: How do insects know what is edible? What is the current scientific consensus on how insects innately know what is food and not food? If they are introduced to new food sources do they experiment with eating the new food? Could you teach a preying mantis to eat beef? Insect feeding behaviour is generally triggered by one or more conditions which may include colour, shape, chemical traces or temperature.
Insects generally locate food based on some combination of olfactory, thermal and visual queues (colour and shape). If their minimum criteria are met to specified tolerance, they will attempt to feed on whatever is nearby using their usual feeding method.
When these conditions appear on the 'wrong' target, it attracts insects and triggers feeding attempts. Insects can be triggered to feed on atypical food sources if the relevant aspects of their environment match those of their normal feeding environments. For example, here is a report from a professor of entomology recollecting his observations of being bitten by pea aphids while handling plants, which he assumes is because of the scent on his hands.
We can exploit this in various ways for research. One is for artificial blood-feeding of insects: most systems, like the Hemotek membrane feeding system, warm blood to the body temperature of the host. They do not normally resemble a target host in any other way. Some blood-feeding insects have very specific requirements for temperature (for example they will only feed on blood if it is heated to the body temperature of birds; the same blood heated to mammalian body temperature will be ignored) but we do not need to make the target look or smell like the natural host. Other species may need olfactory cues, which can be provided by researchers rubbing the membranes on their forearms before placing them on the feeding system, or by breathing on cages as you add the food.
A second way we exploit this is for insect traps. Although not all traps work this way, some work by mimicking the host and attracting insects that are looking for a meal. This can be via olfactory/chemical mimicry (for example carbon dioxide baited traps - try Googling "CO2-baited traps") or visual. Different degrees of visual 'deception' may be needed; for instance to attract tsetse flies, colour is important but shape is not:
The following is multiple choice question (with options) to answer.
if a predator wanted to catch its meal undetected, which method would be effective? | [
"hiding behind a bush with similar colors as itself",
"roaring really loud to scare it",
"none of these",
"peeing to confuse the prey"
] | A | camouflage can be used for hunting for prey |
OpenBookQA | OpenBookQA-838 | human-biology, hair
As for Northern Europeans, blond hair and white skin are actually one of those traits where it's hard to separate random variation from natural selection. It is quite likely there are advantages to being fair in high latitudes where there is little sunlight; you need less protection from the sun in the first place, and you need to be able to get enough vitamin D from sunlight on the other. However this applies much more obviously to skin than to hair. Blond hair is the result of very few mutations, which are thought to have appeared around 11,000 years ago. So it could be that those mutations happened to occur and to spread through those populations and not others and that's why they're blond and most other human populations (Melanesians excepted) are not. Or it could be that once those mutations happened they spread particularly well in those populations because it was adaptive in their environment. The question isn't scientifically settled.
https://en.wikipedia.org/wiki/Blond#Evolution_of_blond_hair
The following is multiple choice question (with options) to answer.
Arctic foxes are white in order to | [
"hide from their predators",
"hide in their environment",
"keep their bodies warm",
"keep their fur clean"
] | B | the arctic environment is white in color from being covered in snow |
OpenBookQA | OpenBookQA-839 | with your consent used more widely as to! The older non-SI term micron thousand gram calories, often appears capitalized and without a prefix unit rather than multiple! The middle portion of the International system of naming units prefixes used historically include hebdo- ( 107 and! Flashcards, games, and other study tools the older non-SI term.! Other multiples or sub-multiples of base units, symbols and prefixes, SI prefixes so the prefixes be may. Used historically include hebdo- ( 107 ) and micri- ( 10−14 ) of.. “ milli ” means one thousand grams and mathematical thinking historically include hebdo- ( 107 ) and micri- 10−14! Varies from common practice for the International system of quantities μ is unavailable agricultural Products, as... One thousand metres, and micro- the universal conversion page.2 Enter the value Greek letter μ is unavailable of! ; Done-for-you FB Ads ; diy Courses ; feel the love Raving Fans ; questions degree Celsius ( )... For large scales, megametre, gigametre, and more beer and wine, are often in! As a shorthand for small or large quantities of a meter, while the common is. Or US units except in some fields, such as grain, beer and wine, often... Though the kilogram has a symbol that is used in the arithmetic measurements... Note 2 ], prefixes adopted before 1960 already existed before SI megametre, gigametre, and the decilitre used... Include hebdo- ( 107 ) and micri- ( 10−14 ) come the.! Beer and wine, are often measured in hectolitres ( each 100 litres in size.! Most standards bodies now regard a megabyte as being, decimal = 1000000000000000000000000, millibarn.. Other metric prefixes are commonly used for measurement of mass as thousand '' is from Roman,! Actually encountered are seldom used. above are applied to other units with the unit! Prefixes rarely appear with imperial or US units except in some fields, such as chemistry, short. Is so named because it was the average length of a meter, while common... Gram instead, treating the gram metric prefixes chart, treating the gram instead, treating the gram
The following is multiple choice question (with options) to answer.
Millilters mL is a unit generally used for values between 1 and 1000 to measure | [
"the space inside a container",
"the height of a container",
"the weight of a container",
"the length of a container"
] | A | milliliters mL is a unit used for measuring volume generally used for values between 1 and 1000 |
OpenBookQA | OpenBookQA-840 | atmosphere, temperature
$R_E$ is the Earth's radius. Using albedo $\alpha$ the absorbed energy can be calculated:
$$P_{\text{E,abs}} = (1-\alpha)P_{\text{SE}}$$
Applying the Stefan-Boltzman law to the Earth, corrected for the emissivity $\overline{\epsilon}$, the emitted energy is then:
$$P_{\text{E,emit}} = \overline{\epsilon} 4\pi R_E^2 \sigma T_E^4$$
Assuming energy equilibrium $P_{\text{E,abs}} = P_{\text{E,emit}}$ we can now calculate $T_E$:
$$\begin{aligned}
\frac{(1-\alpha)4\pi R_S^2 \sigma T_S^4\pi R_E^2}{4\pi D^2} & = \overline{\epsilon}4\pi R_E^2 \sigma T_E^4 \\
T_E^4 & = \frac{(1-\alpha)4\pi R_S^2 \sigma T_S^4\pi R_E^2}{\overline{\epsilon}4\pi D^2 4\pi R_E^2 \sigma} \\
T_E^4 & = \frac{(1-\alpha) R_S^2 T_S^4}{ 4\overline{\epsilon}D^2 } \\
T_E & = \left( \frac{(1-\alpha) R_S^2 T_S^4}{4 \overline{\epsilon}D^2 }\right)^{\frac{1}{4}} \\
T_E & = T_S \left( \frac{(1-\alpha) R_S^2}{4 \overline{\epsilon} D^2 }\right)^{\frac{1}{4}} \\
The following is multiple choice question (with options) to answer.
The slight angle of the axis of the human planet is responsible for the energy allotment that is received by what? | [
"polar areas",
"mars continents",
"free countries",
"all countries"
] | D | the Earth being tilted on its axis causes ones side of the Earth to receive less energy from the Sun than the other side |
OpenBookQA | OpenBookQA-841 | meteorology, climate-change, gas, pollution
If you are interested in Greenhouse Gases (e.g. methane, carbon dioxide, CFCs, nitrous oxide), the EPA has a separate site for those emissions since they are not part of the same regulatory framework http://www.epa.gov/climatechange/ghgemissions/ . Greenhouse gases typically do not cause adverse health effects for plants or animals on land. However, they have long-term radiative effects (e.g. the greenhouse effect) because they stay in the atmosphere for many years and trap infrared light. These long-term radiative effects are what can change climate and consequently land cover. Furthermore, most of the excess carbon is absorbed by the ocean, which creates carbonic acid. Increased acidity of the ocean causes severe problems for marine ecosystems.
The EPA states that in 2012 the CO2 equivalent GHG emissions for the USA by sector was:
The following is multiple choice question (with options) to answer.
What can cause a process that has a negative effect on the environment? | [
"pulleys",
"sharks",
"tillage",
"ice"
] | C | erosion of soil has a negative impact on the environment |
OpenBookQA | OpenBookQA-842 | zoology, species-identification, ornithology, behaviour
Title: What is this crow eating, and is it a common part of the corvid diet? Here's a picture (by Rob Curtis) of a crow carrying and eating the corpse of what looks a bit like a small hawk or falcon:
Other pictures clearly show the crow is eating the dead bird. This image shows the underside of the head and beak; this one shows its legs, which are grayish.
What bird is being eaten?
Is this bird a usual part of the corvid diet? Or did the crow just opportunistically scavenge a dead bird? Crows are omnivorous, and will eat almost anything they find or can kill.
In this case the prey looks like a Yellow-Shafted Flicker.
The following is multiple choice question (with options) to answer.
A parrot has been eating a lot of fattening food. This could lead to | [
"the parrots' parents scolding him",
"the parrot becoming a faster flyer",
"the parrot having trouble getting off the ground",
"the parrot ending up in the hospital"
] | C | as the weight of an animal decreases , that animal will fly more easily |
OpenBookQA | OpenBookQA-843 | mechanical-engineering, structural-engineering, control-engineering
For example, if I wanted to setup such a facility, who would I have to consult?
You either find a consulting engineering firm with a lot of experience in designing and planning (and building!) such a plant. Or you find anexperienced hydroponics expert (the first bullet point) and a consulting firm with experience in a relevant field like wastewater.
Alternativly, you find a company specialized in building and selling hydroponics farms. This will give you less choice over the final plant - the company will want to work with their preferred components and concepts, and crucially they will want to reuse as much egnineering work from previous projects as they can.
The following is multiple choice question (with options) to answer.
We can help a plant by | [
"Telling it a story",
"Cutting it from the roots",
"Storing it in the dark",
"Refusing to water it"
] | A | In the photosynthesis process oxygen has the role of waste product |
OpenBookQA | OpenBookQA-844 | magnetic-fields, earth
Title: Would a compass on its side point at the ground? From a point just north of the equator, A straight line to the Magnetic North would be through the earth. If a compass was turned on it's side, would the north pointing arrow point toward the ground along that straight line? A compass is usually used to find the direction of the horizontal magnetic field of Earth at that point. The needle of a compass is very light and thus its efficiency decreases when the compass is not in the horizontal plane at that point (due to gravity).Therefore, where the compass would point will become unpredictable. But, yes, in ideal conditions, the compass would point along the straight line joining that point to the north pole.
The following is multiple choice question (with options) to answer.
The floating arrow on a compass always points away from the | [
"east",
"north",
"south",
"west"
] | C | the floating arrow on a compass always points towards the north |
OpenBookQA | OpenBookQA-845 | thermodynamics, geophysics
With supercooled water, this effect is even more pronounced - a water at -30 °C has about the same density as water at 60 °C.
Oceans cool mostly by evaporation - the surface layers of water "spontaneously" changing state from liquid to gaseous. You get a balancing act between energy lost to evaporation, and incoming sunlight. However, there's a huge gap between the surface and the deeps, a lot of water mass - the incoming sunlight is nowhere near enough to warm ocean waters throughout. So you get warm surface waters, then a gradient of cooler and cooler water, and finally about 0-3 °C in the deep. To illustrate how big this gap is, about 90% of the worldwide ocean water is in the 0-3 °C range (hence the "nowhere near enough sunlight to heat the whole thing through").
Of course, a 4 °C body of water is great for cooling systems running at 40 °C and more. Air is actually a pretty good insulator, so air cooling gets tricky with large systems. Water, on the other hand, is pretty thermally conductive, and it easily convects, so cooling a huge data centre becomes almost trivial.
EDIT:
Let me address the Sun part, since there seems to be some confusion there as well.
Nuclear fusion is something that happens very infrequently. Two nuclei must come very close together to fuse, and they need enough kinetic energy to overcome the repulsion between each other (since both have the same electric charge).
The first problem is solved by increasing density. The more nuclei you have in the same volume, the higher the likelihood of close contact. This is where pressure comes in - that's how you get a higher density. Stars are made of plasma, and plasma is easily compressible, similar to a gas, so as pressure increases, so does density. How compressed is it? Well, the Sun's core, where the fusion reactions are actually happening, contains 34% of the Sun's mass, in only 0.8% of the Sun's volume. In the centre, the density is around 150 times the density of liquid water. The pressure is about 100 000 times the pressure in the Earth's core, and about 100 000 000 times the pressure of the water on the bottom of the Mariana trench.
The following is multiple choice question (with options) to answer.
The sun causes what to happen to water at a more rapid pace when heat is added? | [
"water volume maintains exactly",
"water levels rise as moisture is held in the water",
"the heat makes the water boil as it reaches higher temperatures",
"heat causes the water to lose volume as moisture is pulled into the air"
] | D | the sun causes water to evaporate more quickly by adding heat |
OpenBookQA | OpenBookQA-846 | water, energy, reference-request, water-treatment
Title: EZ-Water - Fraud or breakthrough? Recently the quack medicine folks online have been promoting the research of a certain Dr. Gerald Pollack who claims to have discovered a "forth phase of water", and who has recently published a book on the said topic.
Although it's clear that his research is being deliberately misinterpreted, it's not clear to me whether or not his own claims are valid in the first place. Although some papers on the topic were published in peer reviewed journals, it doesn't seem like anyone else in the scientific community has acknowledged or replicated his results.
So, is "EZ-water" a real breakthrough or just the brainchild of a deluded scientist? EZ-water is not a breakthrough. It is not new, nor is it valid. This appears to be one of the many claims about the healthful benefits of drinking "ionized water".
The original "article" linked, contains a number of misleading statements.
Water molecules make up 99% of your body. This is true, but misleading. According to various sources, the human body is between 57% and 75% water by mass. Since water has a much lower molar mass than most biomolecules, 99% of the molecules in your body may well be water.
The journal listed in which the research is published is Water, which is not a high impact journal, despite its name. Water had an impact factor of 0.973 in 2012. That means that articles published in 2011 in Water were cited less than 1 time each by anyone in 2012. Compare with Cell, which had in impact factor of 31.957 in the same period - each article in Cell is cited an average of nearly 32 times.
Water has a "fourth phase" and no single boiling point or melting point. This is true! Any student of chemistry should be able to tell you this. Take a look at the phase diagram of water below. Water apparently has at least 18 phases (15 solid phases, plus liquid, vapor, and supercritical fluid). You can also see that the solid-liquid and liquid-vapor phase boundaries are not single points. They are curves varying in temperature and pressure. Those curves represent the conditions in which the two phases have the same vapor pressure. This is not a new discovery or a startling secret. This behavior has been known for many decades (if not centuries).
The following is multiple choice question (with options) to answer.
There are several stages in the way that water cycles, and all are accurate aside from | [
"condensation",
"procepitation",
"precipitation",
"evaporation"
] | B | condensation is a stage in the water cycle process |
OpenBookQA | OpenBookQA-847 | entomology, habitat
Title: Do hornets return to the same nest after winter each year? I have what I think is a hornet nest on the soffit of my house.
The nest has been removed, however, the hornets keep rebuilding. Also, they have started to swarm the sewer vent pipe (not shown in photo).
If fail to get rid of the hornets this fall, will they return to the same nest next year (or overwinter and continue to live there)?
I'm not sure if this is relevant or not:
To give you an idea of what kind of winters I am dealing with, I am near Toronto, Ontario; the temperature goes down to -25 degrees Celsius.
If fail to get rid of the hornets this fall, will they return to the same nest next year (or overwinter and continue to live there)?
No. The nest, likely made of wood pulp (and maybe mud), will/should degenerate to unusable over the winter, though the bulk could remain for a couple of years. All wasps die, except for the new queens (fertile, mated females) who overwinter in sheltered crevices somewhere.
In spring, it is a single wasp that starts a hive: the new queen. She builds a new, small hive in which to lay eggs, which is added to initially by the queen and then by workers who have hatched.
While she will not return to an old hive, the conditions which appeared advantageous to one queen (shelter from rain, intense sunlight, winds, etc.) will also seem advantageous to other queens, which is why nests appear in the same places year after year.
Edited to add: It appears most likely that the queens that overwinter are "new queens", that is, mated female offspring of the queen. H/T @Brian Krause.
The following is multiple choice question (with options) to answer.
Squirrels stay busy in the autumn | [
"storing water",
"amassing pecans",
"planting flowers",
"sleeping late"
] | B | squirrels gather nuts in the autumn to eat during the winter |
OpenBookQA | OpenBookQA-848 | species-identification, zoology, bone-biology, bone
Title: What is this bone from? This object showed up on my fire escape in New York city. It appears to be some kind of bone. It's a bit smaller than an adult human hand. What animal is it from? Given the size and thin/elongated ilia as well as the urban location, I think a domestic cat and/or a raccoon are likely candidates. I'm leaning toward cat.
Cat pelvis:
VCA Hospitals
Ventral view of domestic cat pelvis; Source: BoneID
Raccoon Pelvis
Anterior view of raccoon pelvis; Source: BoneID
I'm not an expert in differentiating these two species' bones. I will note that your specimen is more or less in between the sizes of these two species. Your size is probably closer to the raccoon, but a cat is just more likely given the location.
The most noticeable trait that stands out to me is the size/pointedness of the ischial tuberosity, which better matches that of the cat.
The following is multiple choice question (with options) to answer.
A fox that has white fur | [
"has been bleached or washed",
"is genetically altered and abused",
"is a very clean animal",
"got it from genetics"
] | D | the coloration of fur is an inherited characteristic |
OpenBookQA | OpenBookQA-849 | species-identification, entomology
Title: Big Bug from Peru I'd like to have a name for this guy. There were 5 or 6 of them zipping around the flower bed on the coast of Peru about 120 kms south of Lima. That is a hawkmoth, probably Hyles annei (Guerin-Meneville, 1839). It is one of a number of moth species commonly called "hummingbird," "sphinx," or "hawk" moths in the family Sphingidae.
Beautiful, isn't it? :)
edit - sorry, I originally misidentified this as Hyles lineata - the pattern is slightly different.
The following is multiple choice question (with options) to answer.
Flowers with more pollinators | [
"escalate reproduction",
"increase water usage",
"increase visual appeal",
"decrease reproduction"
] | A | as the number of pollinators attracted to a flower increases , the ability of that flower to reproduce will increase |
OpenBookQA | OpenBookQA-850 | evolution, ecology, natural-selection, adaptation
Title: What are Some Classical Examples of Local Adaptation? Question
Can you please give a list of classical (textbook) examples of local adaptations?
How to answer
Examples don't necessarily need to include what evidence supports this specific example of local adaptation. A simple description of the local adaptation (e.g. coat colour changes from black on dark soil to white on light soil) and an brief explanation of the reason (e.g. because being nicely camouflaged prevents from predation from hawks) is enough.
I think a list of 10 or more such examples would be great.
Definition of local adaptation
Note that I define here local adaptation as differentially adapted subpopulation of a single species (with existing gene flow between subpopulations especially for sexually reproducing species).
Justification for the question
I found surprisingly complicated to find such list online. I think it could be a valuable post for many.
Examples
Examples of local adaptation (that you are free to add in your answer with a description) include beach mice camouflage, altitude adaptation in tibetans and peppered-moth camouflage. Adaptation is a change in a trait as a response to selection. As you ask for local adaptation I assume you want examples where sub-populations have either come under different selection and adapted differently, or cases where sub-populations have come under similar selection but not all have had the necessary genetic variation to evolve, i.e. selection has caused differentiation between sub-populations. Local adaptation can lead to varying degrees of divergence, so some for some examples it may be worth exploring speciation events. Here's some examples:
Galapagos Tortoises
There are two general shapes to the shell of tortoises on the Galapagos Islands. On islands with little low-lying vegetation the tortoises seem to have evolved long necks & limbs and different shell shapes which allow them to reach up more easily.
"The shell distortion and elongation of the limbs and neck in saddlebacks is probably an evolutionary compromise between the need for a small body size in dry conditions and a high vertical reach for dominance displays."
The following is multiple choice question (with options) to answer.
What is an example of hunting? | [
"Cats eating cat food",
"sea otter cracking open clams with a rock",
"Humans going to restaurants",
"A dog eating dog food"
] | B | An example of hunting is an otter cracking open clams with a rock |
OpenBookQA | OpenBookQA-851 | # Conditional Probability of rainfall
1. Apr 26, 2012
### TranscendArcu
1. The problem statement, all variables and given/known data
3. The attempt at a solution
a) P(Pickwick has no umbrella | it rains) = $\frac{\frac{1}{3}\frac{1}{3}}{\frac{1}{2}} = \frac{2}{9}$, which is the answer according to my answer key.
b) For part b we have:
There is a rain forecast which means he will bring the umbrella. The probability that it won't rain is 1/3.
There is a non-rain forecast which means he brings the umbrella with a probability of 1/3 and it will not rain with a prob of 2/3.
P(Pickwick has umbrella | no rain) = $\frac{1}{3} + \frac{1}{3}\frac{2}{3} = \frac{5}{9}$. But the answer is apparently 5/12. What have I done incorrectly here?
2. Apr 26, 2012
### MaxManus
I got the same as you at b) and I cant see why it is not correct.That's no guarantee for that you are correct though
3. Apr 26, 2012
### Ray Vickson
The following is multiple choice question (with options) to answer.
Needing to use an umbrella could be the result of | [
"evaporation",
"condensation",
"altercation",
"precipitation"
] | D | precipitation is when water falls from the sky |
OpenBookQA | OpenBookQA-852 | entomology, parasitology, parasitism
The male (microgametocytes) and female (macrogametocytes) gametocytes are ingested by a female Anopheles mosquito during a blood meal (8) - only female mosquitoes (of pretty much any species) drink blood. The parasites' multiplication in the mosquito is known as the sporogonic cycle (stage C). While in the mosquito's stomach, the microgametes penetrate the macrogametes generating zygotes (9). The zygotes in turn become motile and elongated (ookinetes) (10) which invade the midgut wall of the mosquito where they develop into oocysts (11). The oocysts grow, rupture, and release sporozoites (12), which make their way to the mosquito's salivary glands. Inoculation of the sporozoites into a new human host perpetuates the malaria life cycle (1).
Sources
The following is multiple choice question (with options) to answer.
After a period of discomfort, weight gain, and sharing the body with a growing parasite, a female creature will have | [
"a doughnut",
"a prodigy",
"a meal",
"a clone"
] | B | a mother births offspring |
OpenBookQA | OpenBookQA-853 | Arrange $2$ red books. Arrange the $5$ black books in any of the three positions as [bbb] [bb]. Take $3$ blue books and separate the adjacent bbb and bb. Remaining $3$ books can be arranged in remaining $5$ positions. So,
$\dbinom{3}{1}\dbinom{2}{1}\dbinom{5}{3}=60$
Arrange $2$ red books. Arrange the $5$ black books in any of the three positions as [bb] [bb] [b]. Take $2$ blue books and separate the adjacent bb and bb. Remaining $4$ books can be arranged in remaining $6$ positions. So,
$\dbinom{3}{2}\dbinom{6}{4}=45$
Total: $228$
Part (2): Find number of arrangements where blue books are apart and black books are apart but red books are together
Group the red books and consider as $1$ big red book.
Arrange $1$ big red book. Arrange the $5$ black books in any of the two positions as [bbbb] [b] . Take $3$ blue books and separate the adjacent bbbb. Remaining $3$ books can be arranged in remaining $4$ positions. So,
$\dbinom{2}{1}\dbinom{4}{3}=8$
Arrange $1$ big red book. Arrange the $5$ black books in any of the two positions as [bbb] [bb] . Take $3$ blue books and separate the adjacent bbbb. Remaining $3$ books can be arranged in remaining $4$ positions. So,
$\dbinom{2}{1}\dbinom{4}{3}=8$
Arrange $1$ big red book. Arrange the $5$ black books in any of the two positions as [bbbbb] . Take $4$ blue books and separate the adjacent bbbbb. Remaining $2$ books can be arranged in remaining $3$ positions. So,
$\dbinom{2}{1}\dbinom{3}{2}=6$
Total: $22$
From Part(1) and (2),
## $228-22=206$
The following is multiple choice question (with options) to answer.
Books can be made out of | [
"card stock",
"cement",
"glass",
"copper."
] | A | paper is recyclable |
OpenBookQA | OpenBookQA-854 | astronomy, everyday-life, popular-science, climate-science
Title: Why is the summer, in the temperate latitudes, in average, hotter that the spring? It is common knowledge that the transition from the Spring to the Summer season occurs in the Summer Solstice when the "Sun reaches its highest excursion relative to the celestial equator on the celestial sphere" (as stated in Wikipedia).
It is also stated in Wikipedia' Summer page:
"Days continue to lengthen from equinox to solstice and summer days progressively shorten after the solstice, so meteorological summer encompasses the build-up to the longest day and a diminishing thereafter, with summer having many more hours of daylight than spring."
My question is: why is the summer, in the temperate latitudes, in average, hotter that the spring? A major part of the reason for this is due to the temperature of the ground. While the length of days in the Summer are effectively a mirror of those in Spring, you must take into consideration more than that.
When Spring commences in temperate climates, it is (usually) immediately preceded by winter. Due to the Winter, the ground and/or surrounding bodies of water are very cold. This has the effect of cooling the air for the first part of Spring while the ground/water begins to thaw/warm up. Furthermore, it takes much longer to warm or cool a body of water than a mass of air; even longer to warm or cool the ground and water. Therefore, as Spring progresses and the days become longer (also meaning the Sun is higher above the horizon, thus providing more heating power), the sunlight must first overcome the cooling effects of the ground and water bodies. Near the end of Spring - when the days are sufficiently long and the Sun is much higher above the horizon - you should notice the weather becoming hotter. This is because the ground and water has had time to warm up, which means it is not constantly cooling the air and making it feel colder.
When you then transition to Summer, the ground is already sufficiently warm but the days are still long and the Sun is still high in the sky. This means the Sun can heat the ground, water, and air even more and without any cooling effects. This allows the Summer temperature to be easily higher than that of the Spring temperatures. If Summer were immediately preceded by winter, you might notice the weather getting warmer much more quickly, but the average temperature would be very close to that of the Spring.
The following is multiple choice question (with options) to answer.
A horse is kicked out of the barn on a hot summer's day, because the stalls need mucked, and the workers have difficulty cleaning around the horses. So the horse is standing in the field, in direct sunlight, and begins to overheat a bit. In order to stand the heat better, the horse | [
"eats",
"stamps",
"neighs",
"perspires"
] | D | sweat is used for adjusting to hot temperatures by some animals |
OpenBookQA | OpenBookQA-855 | human-biology, eyes, vision, human-eye
Title: Superhuman eyesight My ten year old son was reading car number plates that were too fast, too far away and at the wrong angle for any of us to read or even believe that it was possible for him to read. We thought he was lying as he reeled off the whole number plate and not just some. My husband went across the road to prove him wrong and get him to admit he was making it up but he wasn't. We even asked people in the restaurant and waiting staff for their opinion and everyone was blown away. I'm totally astonished and slightly freaked out by his sight and I'm hoping someone can explain for me.
Specifics
The following is multiple choice question (with options) to answer.
braille is read by using your fingers to | [
"hold the book",
"hold the flashlight",
"turn the page",
"feel the words"
] | D | the shape of an object can be discovered through feeling that object |
OpenBookQA | OpenBookQA-856 | species-identification, botany
Title: Can you identify this (possibly waterstoring) plant? My son brought home a sapling, and after 4 years in a pot it is now about 30 cm or a foot high (from the "ground" to the top of the "stem"). It doesn't need a lot of water and can go weeks without being watered, in fact it seems to me as if it is storing water in the thicker upper part of its stem. When I water it "too much", new leaves start to grow. There are tiny "blossoms" along the stem, and every now and then small, dark brown, spherical seeds about 2 mm in diameter pop out from the "blossom" and are thrown across the room as far as a meter (about a yard) or two.
What plant is this?
I believe that it is not native to my European home but some kind of decorative plant imported and sold through a florist or imported privately, but I'm not sure. It is an Euphorbia leuconeura (Madagascar Jewel), which is native to Madagaskar. The leaves and the thick (waterstoring) stem with a narrow base is very typical.
The plant is cool in the sense that it easily produces seeds (also as potted) which it can shoot away from the plant. I've had it myself and you can sometimes hear seeds hitting the window or floor. Even if it is easy to grow and to reproduce it is actually considered threatened in its native habitat (IUCN Red-listed as Vulnerable) due to habitat loss
The flowers are very small and found directly on the stem, see below:
(picture from Wikipedia)
The following is multiple choice question (with options) to answer.
a plant needs this to survive | [
"bugs to eat",
"liquid food",
"finger food",
"nutritional material"
] | D | an plant requires food for survival |
OpenBookQA | OpenBookQA-857 | terminology, meteorology
I've tried to illustrate the relationships with insolation and temperature here:
There are some other ways too:
Ecological. Scientists who study the behaviour of organisms (hibernation, blooming, etc.) adapt to the local climate, sometimes using 6 seasons in temperature zones, or only 2 in polar and tropical ones.
Agricultural. This would centre around the growing season and therefore, in North America and Europe at least, around frost.
Cultural. What people think of as 'summer', and what they do outdoors (say), generally seems to line up with local weather patterns. In my own experience, there's no need for these seasons to even be 3 month long; When I lived in Calgary, summer was July and August (hiking), and winter was December to March (skiing). Here's another example of a 6-season system, and a 3-season system, from the Aboriginal people of Australia, all based on weather.
Why do systems with later season starting dates prevail today? Perhaps because at mid-latitudes, the seasonal lag means that the start of seasonal weather is weeks later than the start of the 'insolation' period. In a system with no heat capacity, there would be no lag. In systems with high heat capacity, like the marine environment, the lag may be several months (Ibid.). Here's what the lag looks like in three mid-latitude cities:
The exact same effect happens on a diurnal (daily) basis too — the warmest part of the day is often not midday (or 1 pm in summer). As with the seasons, there are lots of other factors too, but the principle is the same.
These aren't mutually exclusive ways of looking at it — there's clearly lots of overlap here. Cultural notions of season are surely rooted in astronomy, weather, and agriculture.
The following is multiple choice question (with options) to answer.
How many seasons occur in the span of three years | [
"ten",
"twelve",
"eight",
"four"
] | B | a new season occurs once per three months |
OpenBookQA | OpenBookQA-858 | geology, geothermal-heat, mapping, natural-conditions, underground-water
If you are in a desert climate, you may be able to do something similar on a smaller scale. Under a calm clear sky, you can often get frost on the side of an insulator facing the dark sky at night. Modifying this idea, create a large bottom insulated surface coated with a good IR emitter (Titanium dioxide white is one such.) , and run shallow water over it. If you can routinely get 30 C colder than day time air temps, then you only have to store a few days worth of coolth instead of a years worth.
You can make the system above colder by pre-chilling the water with an evaporative cooler
Edit: One source claims 1 degree F per 30 feet starting at around 100 feet. Temperatures above this
however are highly variable from water movement.
The following is multiple choice question (with options) to answer.
A desert environment can support | [
"fish",
"banana trees",
"redwoods",
"insects"
] | D | when a habitat can support living things , living things can live in that habitat |
OpenBookQA | OpenBookQA-859 | species-identification, ornithology
Title: Help me find out what this bird is (description, no picture) A while ago I read about this bird(s) whose species status was not confirmed. This was because they had a very large distribution and birds in adjacent population could breed with each other but birds at each end of the distribution (western Europe and South Asia I think) couldn't. I am pretty sure that they were some kind of gull and from Europe to Asia their wings got lighter, from black to grey. I think I might have read about them in a Richard Dawkins book.
Does anyone know the species I'm talking about? You're describing a Ring Species: "a connected series of neighbouring populations, each of which can interbreed with closely sited related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population".
The classic ring species is the Herring Gull complex, and that's probably what you read about:
The classical example of the ring species model was originally based upon the herring gull complex (Mayr 1942). This group comprises more than 20 taxa of large gulls (Haffer 1982) which together occupy a circumpolar breeding range in the northern hemisphere. ... Mayr envisioned all taxa of the circumpolar chain to be connected by gene flow, while herring and lesser black-backed gulls in Europe, the hypothetical endpoints of the ring, have reached full reproductive isolation and now coexist as distinct species.
--The Herring Gull Complex (Larus argentatus - fuscus - cachinnans) as a Model Group for Recent Holarctic Vertebrate Radiations
However, recent genetic work shows that the situation is even more complicated than this, and it's questionable whether they really are "ring species":
Contrary to the ring-species model, we find no genetic evidence for a closure of the circumpolar ring through colonization of Europe by North American herring gulls. However, closure of the ring in the opposite direction may be imminent, with lesser black-backed gulls about to colonize North America.
--The herring gull complex is not a ring species.
The following is multiple choice question (with options) to answer.
Pelicans have an affinity for | [
"Sushi",
"Cats",
"Trash",
"Mackerel"
] | D | sharp beaks are a kind of adaptation for catching prey |
OpenBookQA | OpenBookQA-860 | 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.
An example of hunting is an otter cracking open clams with a rock, another is | [
"an eagle preening its feathers",
"a fish swimming back upstream",
"a bear swiping at a hive",
"a deer eating grass"
] | C | An example of hunting is an otter cracking open clams with a rock |
OpenBookQA | OpenBookQA-861 | java, programming-challenge
So the Cadbury bar with the size of 5x3 can be distributed to 4
children.
Similarly we can find out number of children for rest of the
combinations (i.e. 5x4, 6x3, 6x4) in the given range as follows:
Please let me know the corrections that I can make to improve the code.
public class CandidateCode {
public int distributeChocolate(int input1,int input2,int input3,int input4){
int[] chocolatelengthLimits = {input1,input2};
int[] chocolatewidthLimits = {input3,input4};
Set<Chocolate> chocolateCarton = makeSetOfChocolatesOutOfTheLimits(chocolatelengthLimits, chocolatewidthLimits);
return getTotalNumberofChildrenThatCanBeFed(chocolateCarton);
}
private int getTotalNumberofChildrenThatCanBeFed(Set<Chocolate> chocolateCarton){
int totalNumberOfChildrenThatCanBeFed = 0;
for (Chocolate chocolate : chocolateCarton) {
int childrenFedFromTheChocolate = numberOfChildrenThatCanBeFedFromTheChocolate(chocolate);
totalNumberOfChildrenThatCanBeFed+=childrenFedFromTheChocolate;
}
return totalNumberOfChildrenThatCanBeFed;
}
private Set<Chocolate> makeSetOfChocolatesOutOfTheLimits(int[] lengthLimits,int[] widthLimits){
Set<Chocolate> chocolates = new HashSet<Chocolate>();
for(int i=0;i<lengthLimits.length;i++){
for(int j=0;j<widthLimits.length;j++){
Chocolate rectangle = new Chocolate(lengthLimits[i], widthLimits[j]);
chocolates.add(rectangle);
}
}
return chocolates;
}
The following is multiple choice question (with options) to answer.
A child has a basket of chocolate eggs for breakfast and as a result | [
"sleeps for the afternoon",
"quietly reads a book",
"runs around all day",
"eats seven more eggs"
] | C | an organism breaks down sugar to release energy |
OpenBookQA | OpenBookQA-862 | visualization, social-network-analysis, metadata
[communities cut]=findcommunitiesatcut(groups,cuts);
rows = max(communities);
mat=spalloc(rows,rows,2*rows);
for i = 1:rows
for j = 1:rows
if(i ~= j)
comm1 = find(communities==i);
comm2 = find(communities==j);
%comm1=comm1(find(comm1));
%comm2=comm2(find(comm2));
mat(j, i) = sum(sum(A(comm1, comm2)));
end
end
end
end
function [communities cut] = findcommunitiesatcut(groups,cut)
%[communities cut]=findcommunitiesatcut(groups,cut)
%
% Gives the community numbers at a requested cut or level in the groups vector,
% if the cut number is not valid the program changes it to a valid one.
% Uses a groups vector and a scalar cut number, gives communities and the cut number,
% which is needed when cut is changed.
%
%
%Last modified by ALT, 20 June 2007
%Error checking
n=unique(groups);
f=diff(n);
z=unique(f);
cutmax=length(z);
if(cut>cutmax)
disp(['That is too many cuts! I have changed the cut number.']);
cut=cutmax;
elseif(cut<0)
cut=cutmax;
disp(['Negative numbers dont work, I have changed the cut number to the max'])
end
%Identify distinct group values and number of cut levels in dendrogram:
groupnumbers=unique(groups);
differences=diff(groupnumbers);
diffnumbers=unique(differences);
cuts=length(diffnumbers);
if cut==0,
communities=ones(size(groups));
else
cutdiff=diffnumbers(cuts+1-cut); %NOTE THERE IS NO ERROR CHECKING HERE, ASSUMED VALID CUT NUMBER
commnumbers=cumsum([1,diff(groupnumbers)>=cutdiff]);
The following is multiple choice question (with options) to answer.
Communities contain | [
"sparse flora and fauna",
"two or three species of similar animals",
"a diverse selection of living beings",
"one species dominating an area"
] | C | a community is made of many types of organisms in an area |
OpenBookQA | OpenBookQA-863 | optics, terminology, reflection
Title: What is a "Gaussian mirror"? What is a Gaussian mirror? I have seen the term used in a book. Gaussian mirrors are supposed to be free of spherical aberration. But what are they? A Gaussian mirror is a mirror whose surface profile is in the shape of a gaussian function, rather than the more typical spherical surface. Spherical surfaces are easier to manufacture, but don't perfectly focus light (i.e. create "aberrated" images or spots due to their geometric shape).
The following is multiple choice question (with options) to answer.
What is most like a mirror? | [
"grasslands",
"deserts",
"oceans",
"forests"
] | C | a mirror is used for reflecting light |
OpenBookQA | OpenBookQA-864 | hybridization
Title: Determine percentage of crow hybrids We had in class following question which I had no idea how to get to the correct answer:
The carrion crow and the hooded crow are fertile together, but their
reproductive success is reduced by 50%. In a certain region exist
two populations of both species of roughly the same size. Thus,
mixed couples occur in about 10% of all cases. What is the percentage of
hybrids in the F1-generation?
(Translated from German.)
I thought it would be something like 5/95 = 5,3% but apparently the answer is 1%. Why? In order to make your reasoning clearer, you should use more formal notations and explain your thinking step by step. Here's a proposition.
Let's use the following notations :
$C$: the total number of couples (mixed and not mixed)
$r$: the reproductive success
$F1_h$: the number of hybrids in the F1 generation
$F1_{nh}$: the number of non hybrids in the F1 generation
You are looking for the percentage of hydrids in the F1 generation, which is:
$x = \frac{F1_h}{F1_h + F1_{nh}}$
You know that $10~\%$ of the couples are mixed couples and that their reproductive success is reduced by $50~\%$. This can be written:
$\begin{cases} 0.9\cdot C \cdot r = F1_{nh} \\ 0.1\cdot C\cdot \frac{r}{2} = F1_h \end{cases}$
Thus: $\displaystyle x = \frac{F1_h}{F1_h + F1_{nh}} = \frac{0.05\cdot C\cdot r}{C\cdot r\cdot 0.95} = \frac{0.05}{0.95}$
This is indeed the result you suggested. So the correction you were given might not be correct. Or maybe there was some more information in your homework that you ignored...
The following is multiple choice question (with options) to answer.
35 percent of what depends on pollination? | [
"flowers",
"people",
"crops",
"bees"
] | C | pollination requires pollinating animals |
OpenBookQA | OpenBookQA-865 | thermodynamics, energy, home-experiment
Additionally, what power rating could I go down to if I were to increase the time to boil by 50%?
As above, if 2000 Watt nominal input gives an ~= 45 minutes to boiling, and the target was < 1 hour, then you'd expect an increase in time to boiling by a factor of 1.5 to 90 minutes to require ABOUT 2000 x 45/90 = 1000 Watts electrical input if thermal losses are able to be scaled down proportionally. With "normal" cooking energy sources adding insulation is problematic but with induction heating adding another towel wrapper and a layer of padding on top is actually feasible. If losses cannot be scaled down then see above calculations for assumed losses and recalculate accordingly.
The following is multiple choice question (with options) to answer.
A household appliance prepares food using electrical energy and | [
"biological energy",
"nothing else",
"heat energy",
"chemical energy"
] | C | a toaster converts electrical energy into heat energy for toasting |
OpenBookQA | OpenBookQA-866 | respiration
Here is what happens at the molecular level.
The $\rm CN^-$ ions diffuse into the mitochondria. They have high affinity to the ferrous ion of the mitochondrial enzyme cytochrome c oxidase involved in the electron transport chain (ETC), one of the phases of cellular respiration where $\rm ATP$ is generated from $\rm NADH$ and $\rm FADH_2$. And it is this process that actually requires oxygen. The inhibited cytochrome c oxidase is of no good in transporting electrons, thus no $\rm ATP$ molecules are generated. The oxygen molecules waiting for those electrons remain empty handed resulting in the increase in the concentration of molecular oxygen. Remember, ETC occurs in almost all living cells except a few like RBC which get their major share of ATP from the highly inefficient anaerobic glycolysis. Also, $\rm ATP$ is the energy currency of our body and is required in a wide variety of bodily processes like osmotic balance, nerve impulse transmission, muscle contraction etc. With no $\rm ATP$ your heart and respiratory muscles can't contract, your medulla can't regulate breathing, your kidneys can't concentrate urine and the list goes on. Death is imminent if a high concentration of cyanide gets into your blood.
The symptoms of panic like tachypnea and tachycardia (that result due to low oxygen in blood) are not usually seen unless the victim himself knows he is poisoned. The end effects like cardiac and respiratory arrest, seizures and coma, however, are similar to those of suffocation.
For further read:
The Mechanism of Cyanide Intoxication and its Antagonism
The following is multiple choice question (with options) to answer.
A waste product of human respiration | [
"is a vital resource to pigs",
"is a vital resource to daffodils",
"is a vital resource to oceans",
"is a vital resource to bees"
] | B | In the respiration process carbon dioxide is a waste product |
OpenBookQA | OpenBookQA-867 | 5. Originally Posted by Nath
"I have 2 children. One is female. What is the probability the other is also female?"
This puzzle appeared in New Scientist magazine, and a similar one in Scientific American several months back. The consensus among mathematicians (according to the articles in the magazines), including a friend of mine (who has PhD in Maths from Cambridge), is that the answer is 1/3.
I've seen several statements which claim to "mathematically prove" the answer to the question is 1/3, but I'm still not convinced. I think it's 1/2.
I'm interested to get some more opinions...
Here is an alternative "logical" way to consider this.
There are 4 possibilities in regard to the children being boy or girl.
The probability of having a boy and a girl is twice the probability of having 2 girls,
and is also twice the probability of having 2 boys.
(i) 1st and 2nd children are girls
(ii) 1st child is a girl and the 2nd is a boy
(iii) 1st child is a boy and the 2nd is a girl
(iv) 1st and 2nd children are boys
GG
GB
BG
BB
One is female.
This reduces to...
GG
GB
BG
3 cases of equal probability and in only 1 of these cases is the other child also a girl.
Hence the probability of the 2nd child also being a girl is 1/3.
Also note that in 2 of these 3 cases, the 2nd child is a boy,
therefore, if one of the children is a girl, the probability that the other is a boy is 2/3.
6. ## Solutions
This was my solution, but alas my friend disagrees:
I have 2 children, 1 is female. This gives four possible scenarios:
1. The female has a younger sister
2. The female has an older sister
3. The female has a younger brother
4. The female has an older brother
Each of these events has a 25% probability, so the probablity the female has a sister = 25% + 25% = 50%.
---
My friend, with the PhD in Maths thinks the following:
The following is multiple choice question (with options) to answer.
Two females usually can produce | [
"children",
"a progeny",
"offspring",
"nothing"
] | D | two females can not usually reproduce with each other |
OpenBookQA | OpenBookQA-868 | thermodynamics, electromagnetic-radiation, blackbody
What generally happens is that after an e.g. visible photon comes in and gets absorbed, the energy is converted to heat, and it is later emitted by a thermal emission as described above.
This thermal emission may be in the infra-red range (for practical temperatures), which you can't see with your eyes.
That's why an object which is both a good absorber and a good emitter looks black when it's at thermal equilibrium near room temperature.$^{[d]}$
Note that this means that black objects are actually radiating more power than white ones, you just can't easily tell because that power is in a wavelength you don't see.
More information
A hypothetical object which perfectly absorbs all incoming radiation is called a black body.
Using quantum mechanics and statistical mechanics you can compute the amount of radiation power a black body at a given temperature should emit at each wavelength.$^{[b]}$
Interestingly, if you look at the plot of the sun's emission, you see that it's pretty close to an ideal black body.
Ever notice that thermal blankets are shiny?
Shiny materials are weakly coupled to the electromagnetic field.
They're shiny precisely because they reflect incoming radiation instead of absorbing it.
Since bad absorbers are bad emitters, this also means that when you wrap yourself in a shiny blanket you will radiate away your body heat more slowly, keeping you warmer in a cold environment.
Of course, wearing a shiny blanket would also prevent you from warming up in the sun light.
The way to think about it is that the shiny thing isolates you from the surroundings: it prevents you from getting warmed by incoming radiation, and it keeps you from getting cold from outgoing radiation.
This is also why thermos bottles are shiny.
$[a]$: Note that the peak radiation power from the sun is at around $500\,\text{nm}$ wavelength, which is right in the middle of the the visible spectrum. Coincidence?
The following is multiple choice question (with options) to answer.
Things that are shiny can reflect light, so all of these will aside from | [
"dog tag",
"ring",
"outlet",
"confetti"
] | C | shiny things reflect light |
OpenBookQA | OpenBookQA-869 | atmosphere, geography
Title: How much atmoshphere is there compared to land and water We know our earth has 71% water and 29% land, but compared to that land and water, how much air do we have in our atmosphere?
I mean:
How big is our atmosphere
Is there any increase or decrease in the amount of atmosphere over time
Is there any change in percentage of oxygen over time 71% of Earth's surface is covered with water and 29% land.
Thinking in that regard, that's saying that on 29% of Earth's "surface" locations you have land below your feet, and in 71% of the locations, you have water. So to continue in such terms, you'd then ask... ok, what percentage of Earth's surface locations would have air above them!?! Well that's all of them. So to if you're comparing it with those percentages, I guess you'd have to say it's another 100%. Or, if we put them together into a full 3-dimensional surroundings at the surface, well it'd basically be 50% air, 36% water, 14% land.
But to compare how much of each there REALLY is, you need to include depth, getting some sort of 3 dimensional understanding of it. But the picture that reveals is certainly not the picture we are used to from daily experience. From the values I was able to find:
In terms of the room each takes up, the volume:
Surface water (oceans+lakes+rivers, glaciers, etc) is 1.4 billion km³
The inside of the Earth is about 1 trillion = 1000 billion km³
For the atmosphere, as mentioned in comments, it's a little more difficult, as the gases only gradually give way to space. You find less and less gas as you go up, but there's no set spot where there is none, as some tiny amount is always floating off into space. So where do you draw the line? A commonly used boundary between the atmosphere and space is the Karman line. This would lead to a volume of 53 billion km³ (using Earth's radius = 6371 km). Note that only about half of that is in the troposphere and stratosphere, which are perhaps the familiar zones of the atmosphere where weather and the ozone layer (and 95% of air molecules) reside.
The following is multiple choice question (with options) to answer.
95% of the world's H2O is found in the | [
"antartic",
"artic",
"seas",
"lakes"
] | C | oceans contains most of earth 's water |
OpenBookQA | OpenBookQA-870 | botany, plant-anatomy
Title: Is it possible to grow any kind of plant soilless (hydroponics)? Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil. [wikipedia]
My question is if is it possible to grow any kind of plant soilless (hydroponics)? Yes, There are a few i know of, a quick "air plant" google search will get you quiet a lot.
wiki 1
wiki 2
Edit: I just glanced through the hydroponics article, and now I wonder if my answer actual answers your question.
The following is multiple choice question (with options) to answer.
Soil is an example of what type of resource for growing plants? | [
"Renewable Resource",
"Abundant Resource",
"Natural Resource",
"Recycled Resource"
] | A | soil is a renewable resource for growing plants |
OpenBookQA | OpenBookQA-871 | organic-chemistry, everyday-chemistry, experimental-chemistry, biochemistry, food-chemistry
Title: How Bread is made with yeast, sugar and luke warm milk? Materials and Apparatus:
wheat flour
sugar
dry yeast
glass bowl
covering plate
milk
Procedure:
Lukewarm milk is taken in the glass bowl and sugar is added to it. Then, yeast is added to the same.
The mixture is left undisturbed for 10-12 minutes to activate the yeast
3 cups of wheat flour are added to the bowl containing the milk mixture.
The mixture is mixed thoroughly with 100ml of added water and the dough is kneaded well
The dough is placed in a bowl, covered with a plate and left undisturbed for 2 hours.
My query/confusion:
Why is milk needed?
"activated yeast"- what's the difference?
Can yeast work without sugar or milk.
Detail out the stages of the anaerobic oxidative process which takes place as a common first step in both aerobic and anaerobic respiration.
Finally, feel free to share anything I may be missing which should be here.
If you have any confusion regarding what I want to ask, please ask in the comments. Please upvote if you are curious about it too
milk is not needed, 'pure' bread is without milk
yeast is a fungus, therefore, it is alive. Its best to work with fresh yeast, which you find as small cubes in the refrigerated section. This one does not have to be activated. non-fresh yeast is dried, so in order for it to work properly, it has to be undried by adding water, which is called activation.
and 4. As said before, milk is not needed. Sugar however is the food for the yeast, without it, it does nothing. In aerobic breathing, the yeast metabolizes the sugar as we would: sugar + oxygen -> water + CO2. Without oxygen, the yeast resorts to ethanol fermentation: sugar -> alcohol + CO2 (this is, why it is used to make beer or wine). For making bread, we have a mixture of both respirations, which does not really matter, since we are only interested in the CO2, which makes the dough fluffy =) But without sugar, there is no CO2.
The following is multiple choice question (with options) to answer.
Toasting bread makes it | [
"smaller",
"longer",
"wider",
"harder"
] | D | cooking causes a chemical reaction |
OpenBookQA | OpenBookQA-872 | the-moon, earth, light, satellite
Title: Why does the Moon appear gray when passing between the Sun and the Earth? Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth?
The photo was taken by DSCOVR at Lagrange point 1.
In the picture, The Moon appears dark gray. Of course the Earth appears bright, reflecting sunlight from clouds and water. The Moon's surface is gray and should reflect less light than the Earth.
It should be irrelevant that we see the far side, since the reflectivity of the Moon's surface should be the same on the far side as the side that faces the Earth.
The midnight full Moon appears much, much brighter as seen from Earth than it does in this picture, despite the fact that the amount of sunlight reflecting from the surface of the Moon is the same in both instances.
I understand the photo was taken with 3 separate exposures of red, blue and green, but this should not affect the brightness.
So why does it appear so dull? That's what it really would look like if you were there with DSCOVR. The albedo of the Moon is only about 0.136, about half of the Earth's average albedo. Of course the part with clouds is higher.
I was shocked too, but it was explained in written copy that accompanied the release of the original image.
Shouldn't the Moon appear as bright as a full Moon seen at midnight from Earth?
It does. If the moon were a diffuse, white ball, a full moon would be about seven times brighter!
If you watch the image or GIF, the Moon is roughly the same brightness as central Australia or the Sahara region.
Phil Plait explains well in Bad Astronomy.
There's a lot to read here.
EDIT: I just ran across these images of astronauts on the surface while reading this answer. Their suits are not 100% white to begin with, but the Lunar soil - at least in these locations - is significantly darker. It is close to the same color as the (presumably) nearly-black radiator fins for the heat sink of the RTG unit (2nd photo) at the astronaut's foot.
above: "Buzz Aldrin carries the EASEP." from here
above: "Astronaut Alan L. Bean from Apollo 12, put the Plutonium 238Pu Fuel from the Lunar Module into the SNAP 27 RTG" from here.
The following is multiple choice question (with options) to answer.
The moon reflects sunlight to arrive at | [
"the moon",
"the ocean",
"orbiting satellites",
"the space station"
] | B | the moon reflects sunlight towards the Earth |
OpenBookQA | OpenBookQA-873 | Here, since counting the number of total fish in the pond is hard, they tagged 50 and let them disperse evenly in the population. Then they caught 50 and found 2 to be tagged. So approximately 4% of the fish were tagged. So 50 is 4% of the entire fish population of the pond. Note that the method uses huge approximation because of the small sample number. If 1 more tagged fish were caught among the 50, it would change the approximated fish population number by a huge amount. But they have given us that "the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond" so we can make this approximation.
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Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
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27 Mar 2016, 12:49
Is it a 600 level question or more?
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Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
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21 Feb 2017, 02:30
Hi can you help me with this problem? The last part of the problem It is not clear for me. I don't know if I have to use 50 fish or 48 fish still in the pond
- 2 fish tagged / 50 in the second catch
- 48 fish are still in the pond
So the equation is:
48 fish tagged in the pond/Tot in the pond = 2 fish tagged out/50 fish catched
Tot in the pond = 48*2/50 = 1200 (aprox. 1250) --> answer is C
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Re: In a certain pond, 50 fish were caught, tagged, and returned [#permalink]
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30 Apr 2017, 11:41
Sachin9 wrote:
so, x * 4% = 50
The following is multiple choice question (with options) to answer.
A pond can be a community because | [
"fish and frogs get along",
"there is a mix of life",
"life forms gather together",
"there is a lot of growth"
] | B | a community is made of many types of organisms in an area |
OpenBookQA | OpenBookQA-874 | special-relativity, speed-of-light
Title: Humans Reaching Andromeda? In a general astronomy class, the professor said that Andromeda, being 2 million light years from the Milky Way, would never be reached by humans. But it seems to me that we may be able to reach a significant fraction of light speed using technology like what was envisioned in the Orion project -- we would have to improve on Orion technology but the point is, near light speed does not seem out of the question.
If this is so, then with relativistic time-dilation, some brave astronauts would experience an arbitrary short amount of subjective time and so could reach Andromeda or even galaxies farther away than that. Given near light speed, is there any reason a spacecraft could not travel that far?
EDIT: I want to clarify that given the technology to reach the closest star in a reasonable length of time and return, it seems like we get any distance as a "free" side effect -- is that the case? I realize that the big difference is that while a trip at .99c to Alpha Centauri can even be in theory a roundtrip, to Andromeda the astronauts would know millions of years had passed on Earth so the return would probably not be undertaken but as far as reaching the nearest galaxy, that seems almost as feasible as reaching the nearest star. You could certainly get to Andromeda if you can travel fast enough, but how are you going to travel fast enough? You could run the calculations - at $0.2c$ (which is way faster than any artificial object has travelled before), relativistic corrections would be insignificant, and it takes $10$ million years to get to Andromeda. That's longer than recorded human history. Even if you go much faster at $0.99c$, the Lorentz factor is still only about 7, Andromeda is still $280,000$ light years away, and it still takes too long to get there.
The following is multiple choice question (with options) to answer.
Human astronauts have visited | [
"the closest celestial object to earth",
"the closest planet to Earth",
"the closest sun to Earth",
"the closest space to Earth"
] | A | the moon is the celestial object that is closest to the Earth |
OpenBookQA | OpenBookQA-875 | water, pressure, building-physics
Title: Water flushed down, water pumped up (in buildings) I live in a tall building (20 floors) on a mountain. Because the water pressure from the water company is not enough, there is a water pump at the last floor which is activated each time someone is using fresh water in his apartment.
To me, that's a big waste of energy, and I think that in theory it would be possible to reuse the used water which is going down to pump some fresh water up.
I wonder if such device already exist on the market, and I would like to know how such device would be called. Would there be a problem to operate with such a height difference? In theory, yes, this could be done. Pretty much exactly as much gravitational energy is lost by the water coming down as is gained by the water going up, so you could then supply the water while hardly using any energy at all. (Just enough to offset the heat generated by friction in the pipes.)
One way in which it can be done in theory is simply to connect two gear pumps with a solid axel. Water from the down pipe will force the axel to turn, which then drives the up pump. Water can be made to flow by applying just a little bit of extra torque to the axel.
However, in practice I don't think this would be done. I imagine there would be a lot of practical issues involved in passing waste water through a pump - it would at least have to be filtered first - and as EnergyNumbers points out in a comment, the energy needed to pump water up 20 floors is pretty small in comparision to (for example) heating the apartments.
The following is multiple choice question (with options) to answer.
If I were recreating water going in and out, I would need to make sure | [
"I paint the water orange",
"I include the animals",
"I use the sun for gravity",
"I repeat it twice"
] | D | the tide cycle regularly occurs twice per day |
OpenBookQA | OpenBookQA-876 | optics, geometric-optics
EDIT:::Clarifications
This question is the result of a debate with my friend, who says the room would be dark and me who says otherwise.
Now being said that let's move to specifics...let's assume that the room is a cuboid and the light source is say a light bulb i.e. an isotropic source like a typical room at ceiling. and the observer with infinitesimally small view port looking from one of the wall presumably neither the ceiling nor floor.
I hope this suffices. You use the verb "to be," which is rather deceptive in this situation (and in questions of optics generally). The room itself would not "be dark" or "be light," it would be a collection of various particles, some of which would be photons in the visible spectrum. It really only makes sense to ask how the room would appear to an observer looking through the viewport.
Even if you had completely reflective surfaces, the way the room appeared would depend significantly on the orentientation of the mirrors, the orientation of the viewing hole, the focus of the light, and perhaps most importantly, the refractive and diffusive properties of the mirrors. Ultimately, the appearance of the room would be a result of the light that falls upon the viewport. While there are an infinite variety of possible arrangements, the two extremes roughly align with the two possibilities you suggest.
For the room to look completely dark, no light paths fall on the viewport. A laser perpendicular to two parallel mirrors with the line of sight also parallel to the mirrors would produce this effect.
For the room to look completely bright, all (or however much you require to meet that definition) light paths fall on the viewport. A room in the shape of a truncated paraboloid with the viewport at the focal point would produce this effect.
Edit
I decided to move these up to my answer to avoid a prolonged comment conversation.
The following is multiple choice question (with options) to answer.
A boy is standing in the bathroom brushing his teeth, but the lights are off in the bathroom. However, his room is next to the bathroom and his bedroom light is on. The bathroom is still bright, because the mirror reflects | [
"light from a car",
"light from the sun",
"light from the bathroom",
"light from the bedroom"
] | D | a mirror reflects light |
OpenBookQA | OpenBookQA-877 | inorganic-chemistry, acid-base, everyday-chemistry
$$\ce{H2O + CO2(aq) <=> H2CO3}$$
and the protolysis of true $\ce{H2CO3}$
$$\ce{H2CO3 <=> H+ + HCO3-}$$
For a weak acid
$$\begin{align}
\log[\ce{H+}]&\approx\frac12\left(\log K_\mathrm a+\log[\ce{H2CO3^*}]\right)\\
&=\frac12\left(-6.3-5.0\right)\\
&=-5.65\\
\mathrm{pH}&=5.65
\end{align}$$
Thus, pure rain in equilibrium with the atmosphere has about $\mathrm{pH}=5.65$. Any acid rain with lower $\mathrm{pH}$ would be caused by additional acids.
The following is multiple choice question (with options) to answer.
Why is acid rain unhealthy? | [
"because it causes drought",
"because it evaporates too quickly",
"It contains various detrimental particles from the air",
"because it causes algae growth"
] | C | acid rain has a negative impact on water quality |
OpenBookQA | OpenBookQA-878 | 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.
powered on lightbulbs burst with cold water because they | [
"electricity and water repel each other",
"the inside is also cool",
"the water starts to boil",
"the inside is hot"
] | D | electrical current running through a wire causes that wire to heat up |
OpenBookQA | OpenBookQA-879 | energy, sun, stars
Then figure that cooking meat with sunlight does require at least some sort of magnifier, so we can probably multiply that by a factor of at least 3, and probably more like 7-10 or so.
Of course, for now I'm ignoring a such minor details as how you even design (not to mention building) a system even close to that size. There would be decidedly non-trivial challenges involved. For example, the largest mirrors we've built yet have diameters around 10 meters (or non-round mirrors of roughly equivalent area). These are already built in sections, with a computer to control movement of the individual pieces to maintain the illusion of a single mirror acting as a unit. Trying to multiply that out to multiple kilometers--well, I don't think anybody's even contemplated what that would take yet.
The following is multiple choice question (with options) to answer.
What can build something over millions of years? | [
"a river",
"a person",
"society",
"dinosaurs"
] | A | a canyon forming occurs over a period of millions of years |
OpenBookQA | OpenBookQA-880 | inorganic-chemistry, home-experiment
Title: Make a silver zinc battery I have a shaver that runs off a rechargeable battery that is dying. Would it be feasible to make a silver zinc battery and use it to replace the existing battery? Cost is not an object, anything less than $2500 I would consider doable. I have a machine shop and a small chemistry laboratory with the standard equipment and glassware, including high vacuum capability, a centrifuge and simple glass blowing capability.
I found a book on silver-oxide zinc chemistry and battery design, but it is $500 and I don't want to spend that if the information can be obtained just as easily elsewhere.
I have tried to find commercial options, but had no luck. Most silver zinc batteries seem to be just for large (multi-million dollar) military or satellite applications. Sony makes a line of silver oxide primary cells for hearing aids, but these are not rechargeable. There is a company called Ultralife that makes medical and military batteries and might have something viable, but before I call them I wanted to check out the opinion of the experts here. This turns out to be very difficult to do for two reasons. One problem is that the voltage of a silver cell is different from that of Ni-Cd cell, so it would require a specialized, multi-cell configuration to emulate the voltage characteristics of the Ni-Cd rechargeables.
The other problem is that silver cells generally have a sophisticated frame inside of them that is produced by an intricate high-temperature welding process. To duplicate this process and produce a suitable frame would require a significant amount of experimentation and work.
The following is multiple choice question (with options) to answer.
Flashlights require batteries | [
"to properly illuminate objects",
"to be used as a weapon",
"to meet weight requirements",
"to illuminate bright rooms"
] | A | a flashlight requires a source of electricity to produce light |
OpenBookQA | OpenBookQA-881 | newtonian-mechanics, conservation-laws
So generally the plate will move : it could translate and also rotate. Constraining forces (and torques) would be needed to keep it in place. If it is released it will move.
The following is multiple choice question (with options) to answer.
If a car is stuck and people need to move it | [
"they use horses to pull it",
"they are really stuck",
"they use their bodies to shove",
"they push it into the air"
] | C | pushing an object requires force |
OpenBookQA | OpenBookQA-882 | 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.
an animal is controlled by a | [
"collection of neurons",
"friend",
"weather condition",
"higher power"
] | A | an animal 's brain controls that animal |
OpenBookQA | OpenBookQA-883 | food, nutrition, energy-metabolism
Title: What are the bare minimum nutrients required to survive as a human? I am trying to determine the bare minimum nutritional requirements to survive as a human, ignoring energy (caloric) requirements. Another way to ask this question is: What elements can humans not live without? I am not inquiring solely about what nutrients are needed, but also their approximate amounts.
Imagine pills that a person can take that covers all their base nutritional needs and that after taking this pill the person can eat whatever they want to meet their caloric requirements. Hypothetically, this pill could have some amount (how much?) fat, carbohydrates, protein, fiber, minerals, and vitamins, and the person could subsequently eat any other food to meet their caloric requirements knowing their nutritional needs would already be otherwise met. Lets ignore the possibility of the person suffering from health issues due to eating too much of any specific food to meet their caloric requirements (e.g., taking the magic pills and then eating only butter).
A person in this situation could think "Ok I've got most of my bases covered, now I just need to ingest another 1000 calories of (almost) anything I want).
What nutrients are absolutely necessary for humans to survive indefinitely, and how much of these nutrients are required?
I am hoping for a complete list with approximate amounts (e.g., 20g fat, 20g carbohydrates, 1mg Vitamin X, .05mg Vitamin Y, 10mg mineral X). Essential nutrients include (NutrientsReview):
Water
9 amino acids: histidine, isoleucine, leucine, lysine, methionine,
phenylalanine, tryptophan, threonine, valine
2 fatty acids (alpha linolenic and linoleic acid)
Vitamins: A, B1, B2, B3, B5, B6, folic acid, biotin, B12, C,
D, E and K (and choline, which is considered a vitamin-like substance)
Minerals: calcium, chromium, chloride, copper, iodine, iron,
manganese, molybdenum, phosphorus, potassium, selenium, sodium, zinc
The following is multiple choice question (with options) to answer.
What requires nutrients to grow and heal? | [
"birds",
"computers",
"dirt",
"metals"
] | A | an animal requires nutrients to grow and heal |
OpenBookQA | OpenBookQA-884 | condensed-matter, solid-state-physics, thermal-conductivity, phonons
How does this phonon picture explain the fact that when we heat a bad conductor the heat propagates gradually from the hotter to the cooler end? If they are delocalized collective excitations, shouldn't they heat up all parts of the substance at the same time?
I think that here the answer is simply that you need some time for the "delocalized collective excitation" you are talking about to set in. This must be true even for a perfect crystal, even if its infinite thermal conductivity would seem to suggest the opposite, otherwise we would have instant propagation of a signal (the vibration of the atoms). You think about the phonons as "delocalized collective excitation", but in reality they are much more similar to wave packets arising from a superposition of these collective excitation (the normal modes of the crystal). Maybe I am not being 100% precise in my terminology here, but I hope that I managed to convey the general meaning of what I have in mind.
References
[a] R. Peierls, “Zur kinetischen Theorie der Wärmeleitung in Kristallen” ("On the Kinetic Theory of Thermal Conduction in Crystals")
Ann. Phys. 395, 1055–1101 (1929)
The following is multiple choice question (with options) to answer.
A thermal conductor is made of | [
"types of rubber",
"types of wire",
"electrodes",
"that which conducts"
] | D | a thermal conductor is made of materials that conduct thermal energy |
OpenBookQA | OpenBookQA-885 | ecology
Title: Do invasive species cause long-term damage to ecosystems they invade? Growing up in the U.S., I was warned at various times of the dire consequences of a variety of introduced pests (usually insects).
Japanese beetles, gypsy moths, and most recently the brown marmorated stink bug are all introduced pests that, at various times, were described as serious threats to our ecology.
These threats aren't confined to arthropods, either. The giant African land snail is causing a stir in Florida (indeed, Florida seems to suffer from an excessive variety of introduced species.
"Lack of native predators" is frequently cited as the primary reason many invasive species are considered such a risk to the ecology.
I understand that these introduced species can place tremendous pressure on native species that fill similar ecological niches, and may even push these species out of the region due to competition for food and habitat. However, do the overall ecologies that these species are introduced to adjust over long periods of time?
The numbers of Japanese beetles and gypsy moths don't seem anywhere as high as when I was a child. Has the ecosystem adjusted, or has the overpopulation self-corrected as the species ran low on food through over-consumption? Or are the populations still just as problematic now as they were 30 years ago, and I just am not seeing the bigger picture?
What is the long-term impact that we've seen from invasive, introduced species? Is there a significant difference on the long-term impact between introduced flora, arthropods, or mammals? The answer really depends on how you think of invasive. One extreme answer is to say that all things are relative, and that the concepts of local and invasive are all relative. This matters to a certain extent because ecologists draw a fuzzy line between invasive and naturalized. You could start with some basic species that we all think of as either good, local, or neutral. Take the earthworm. Most people think of it as a common native species, but the earthworm is actually an invasive species that has radically changed much of North America that came over with the Europeans. Similarly, brown trout are also invasive, coming to the US in the 1800's.
The following is multiple choice question (with options) to answer.
Invasive plants in an ecosystem often lead to | [
"overpopulation",
"rainy weather",
"rashes",
"GMOs"
] | A | if the population of an organism increases then the ecosystem may become overpopulated with that organism |
OpenBookQA | OpenBookQA-886 | 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.
Where does a lightbulb send electricity to generate heat? | [
"glass sphere",
"plastic circle",
"block of metal",
"metal thread"
] | D | an incandescent light bulb converts electricity into heat by sending electricity through a filament |
OpenBookQA | OpenBookQA-887 | thermodynamics, water
Use case/origin of this question
I was getting water from the break room and I have the option of either hot or cold water... So if I had to pick, and not mix, which I do, then ... that's how I started wondering about this. :) For the original case, I would expect the warmer one to reach equilibrium quicker.
This for two (probably quite small in practice) reasons. First, the warmer one will evaporate more of it's water than the cooler one. It may not be a significant amount of evaporation; but any evaporating would reduce the amount of mass to be cooled. Depending on how you set up the scenario, getting the water to 10 degrees hotter would cause evaporation before you even start the timers.
The second reason is due to thermal convection. Heat rises, so when you have water warmer than the surroundings, this would cause more airflow upwards from the container, compared to cool water where the air would be more prone to stagnate on top, reducing the convection; thus reducing the heat transfer.
Increasing surface area of the water will only make these two effects more pronounced for the warm water, by increasing the surface area for evaporation and convection.
Increasing the ambient to 80 degrees shouldn't really change this.
The rate of change will not be completely constant. For starters, as both approach equilibrium, the heating and cooling will slow down. Also, the rate may be affected by stagnation in the water itself. The cooler bucket may decrease it's heat transfer rate as a layer of warmed water begins to develop on top. This would greatly reduce the heat transfer rate on top, only getting worse as that layer gets closer to equilibrium. This doesn't happen with the warmer bucket, because the cooler room cools the water surface, and that water sinks below the warmer water, leading to natural convection.
The only way I can think of that you might get different results is if you kept the water in a sealed container, and kept it closed with an insulated lid, while having the sides of it conductive. I'm not even sure if that would work though, it would just eliminate evaporation and reduce the effects of stagnant convection.
The following is multiple choice question (with options) to answer.
As water gets warmer | [
"it can cause hypothermia",
"it will stick to metal surfaces",
"it can freeze solids",
"it can turn ice into a puddle faster"
] | D | as temperature increases , the ability of that liquid to dissolve solids will increase |
OpenBookQA | OpenBookQA-888 | thermal-conductivity
$$T_\text{interface}=\frac{\sum_i(k_iT_i/L_i)}{\sum_i (k_i/L_i)},$$
and so the heat flow is $q=A\frac{T_1-T_2}{\sum_i R_i}$, which holds generally for even $i>2$ if the end temperatures are taken as $T_1$ and $T_2$. Note that the thermal resistances (not the thermal conductances $1/R_i$) end up adding.
The following is multiple choice question (with options) to answer.
An example of thermal conductivity is | [
"Leaving a fire log poker in the fire place",
"Sitting down on a bed",
"Throwing a large ball",
"Yelling into a megaphone at a crowd"
] | A | thermal conduction is when materials conduct heat through those materials |
OpenBookQA | OpenBookQA-889 | metabolism, energy, physiology
Title: Glycolytic non-oxidative pathway I am currently digging in some books to understand the three major metabolic pathways involved in physical training. The most difficult one for me is the glycolytic non-oxidative pathway (also more commonly known as the anaerobic lactic pathway) and I would like some help from people versed in this field.
In this pathway, as far as I understand, glycolysis produces pyruvate. In this process, NADH and H+ ions are produced along the way.
Then, if there is still a high energy demand (i.e. glycolysis is still necessary); NADH binds with pyruvate to form lactate and free up NAD+ which is necessary to sustain the glycolysis (otherwhise, pyruvate would be consumed via an oxidative pathway i.e. oxidative glycosis or slow glycolysis). This can theoretically continue until glycogen is depleted or severely diminished as far as I understand.
The problem comes then from the H+ ions produced during the glycolysis. These ions cause acidosis of the muscles if not removed. However, they can be removed if sufficient oxygen is present to form water. And here is my main question :
Why, during high intensity exercise, would oxygen be insufficient to take care of the H+ ions produced by the glycolysis ? Is it because muscles used during high intensity are not the best ones for using/transporting oxygen? Is it also because these H+ ions cannot be transported towards neighbouring muscles able to oxidise H+ ions ?
I understand this is a difficult question and maybe there is no precise answer at the moment. If you could point me toward a good ressource that deals with this question, I would be glad. I currently base myself on McArdle book on exercise physiology. I am going to try to walk through this problem, in a step-by-step manner in relation to exercise, starting from at rest, and ending at the point in which the body is no longer able to maintain its energy-charge.
At Rest
The following is multiple choice question (with options) to answer.
running turns carbohydrates into | [
"fat",
"sweat",
"motion and heat",
"protein"
] | C | moving changes stored energy into motion and heat |
OpenBookQA | OpenBookQA-890 | astrophysics, main-sequence, protostar, t-tauri-stars
A Jeans-unstable cloud of gas and dust begins to contract, exchanging gravitational potential energy for kinetic energy, and thus heat. The luminosity of the protostellar cloud increases as it collapses. It takes around 100,000 years for the initial period of rapid collapse to finish, at this point the cloud is very luminous (perhaps 20 solar luminosities and 8000K).
Over the next 1 million years, the protostellar cloud slowly contracts and cools to around 4500K. The protostar then travels down the Hayashi track, contracting further but changing little in temperature - its luminosity continues to fall. This is the stage where T Tauri stars are at. Most T Tauri stars are younger than 3 million years old.
The star then follows the Henyey track, where the luminosity begins to slowly increase again as a radiative zone develops in the star's core and it continues to slowly contract. This can take some tens of millions of years.
Finally, the conditions in the core are extreme enough for fusion to begin. The timescale from all the energy being provided by gravitational contraction to all the energy being provided by fusion, is on the order of 1 million years. The star's luminosity (counter-intuitively) decreases again when this happens, as the energy from fusion doesn't quite offset that from gravitational contraction, which ceases when fusion begins.
Figure: the The Lg/L curve describes the amount of energy gained from gravitational contraction over the total luminosity of the star. The logarithmic time axis is in seconds (reproduced from Iben (1965), Figure 3).
References:
I. Iben (1965), Stellar Evolution. I. The Approach to the Main Sequence
R. Larson (1972), The evolution of spherical protostars with masses 0.25 M_solar to 10 M_solar
L. Henyey et al (1955), The Early Phases of Stellar Evolution
Interesting reading I came across for somewhat higher mass protostellar formation:
F. Palla and S. Stahler (1991), The evolution of intermediate-mass protostars. I - Basic results
The following is multiple choice question (with options) to answer.
Miletinae in the air above will have gone through a transmutation and would have already gone through what pre imago but post egg stage ? | [
"egg stage",
"old stage",
"stage after larva",
"moth stage"
] | C | the pupa stage is a stage in the metamorphosis process of some animals |
OpenBookQA | OpenBookQA-891 | classical-mechanics, energy, electricity
Title: Can we imagine having a computer keyboard that recharges itself through mechanical utilization? Silly question here.
I have a debate with my father, and while I am decent at high school level physics, both he and I cannot determinate through calculus which of us is wrong.
Basically, he had the idea that perhaps, through simple mechanical utilization, a wireless keyboard can be charged and used, without any other energy source. (The keyboard can have a battery that can be recharged through the said mechanical utilization though), I have the intuition that the idea is interesting, but physically problematic.
With simple research, I have seen that an idle keyboard has a consumption of $1W$, and a used keyboard will use between $1.5$ and $2.5W$.
So, we have specific questions:
Is collecting the mechanical energy from the keyboard doable ?
And if yes, how much energy can typing on a keyboard's key produce ?
How it may impact the overall comfort of the user ?
I have multiple difficulties to answer these myself. How can I know how much a person can generate through typing, how much energy will be lost in the process of using a battery, etc..?
(This is not a concept that I try to sell or anything, this is a mere thought experiment that I wanted to share and resolve, please do not take it too seriously) What you are looking for is fairly simple. All you need to do is build a piezoelectric generator under each key. These generate electricity with each push. With this the element is stretched or vibrated with each push and this generates electricity. Do a Google search and you will find much more.
The following is multiple choice question (with options) to answer.
I need electrical energy to | [
"Go running",
"cook some bread",
"Ride a bike",
"Go swimming"
] | B | a light bulb requires electrical energy to produce light |
OpenBookQA | OpenBookQA-892 | ecology
I have tried to find explanatory texts both in this and other books without any success so my question is how's this balanced state achieved in both types of successions (the answer is hinted in the first paragraph which I don't quite understand)?
Related to my last post. The author is saying that 1) Mature ecosystems tend to have a balance between production (=P) and use (=R, respiration) of biomass. This is actually tautological because the author would probably define a mature ecosystem as one where this is true (P=R).
If it starts out P > R, the autotrophs are dominant: more biomass is being produced than used up. It is possible, for a time, that P will increase as, for example, plants grow more leaves, but R is growing too, and there is an eventual limit on P, which at maximum depends on the light available to the ecosystem. As biomass grows, so does the amount of biomass to potentially decay, so eventually R will always catch up to P, until there is balance.
If it starts out P < R, that means you are using up biomass faster than you are creating it. This case is even simpler: you will gradually run out of biomass, and R will decrease.
In either case, when the author is talking about P = R, this is going to be in relative terms; there might still be variations between them, for example seasonal variation, but on average over years or decades you would expect P = R in a mature, stable ecosystem.
The following is multiple choice question (with options) to answer.
Producers provide an ecosystem with | [
"glucose",
"carbon dioxide",
"water",
"glucosamine"
] | A | a producer is a source of sugar in an ecosystem |
OpenBookQA | OpenBookQA-893 | thermodynamics, temperature, units
My personal favorite way to do it is to measure entropy in bits, so that $k_B = \frac{1}{\ln 2} \,\mathrm{bits}$ and the units of temperature are $\mathrm{J\cdot bits^{-1}}$. Having entropy rather than temperature as the quantity with the fundamental unit tends to make it much clearer what's going on, and bits are a pretty convenient unit in terms of building an intuition about the relationship to probability theory.
The following is multiple choice question (with options) to answer.
What is a unit for measuring heat energy? | [
"kg",
"m",
"s",
"F"
] | D | temperature is a measure of heat energy |
OpenBookQA | OpenBookQA-894 | newtonian-mechanics, energy-conservation, work, potential-energy, biology
Title: If I lift a body with a force greater than its weight, what will happen to the excess energy provided to the body I will give an example to explain my question.
Case 1:
An elevator lifts body a with force equal to its weight for a distance $d$
Energy given to the body (work done)$=$ Weight $×$ $d$
Amount of work the body is capable of doing by falling down (gravitational potential energy) $=$ Weight $× \ d$
Case 2:
An elevator lifts the same body with force equal to twice weight it’s for a distance $d$
Energy given to the body (work done) $=$ $2 \ ×$ weight $×$ $d$
Amount of work the body is capable of doing by falling down (gravitational potential energy) $=$ weight $×$ $d$
So doubled the amount of energy I gave to the body yet it’s capacity to do work by falling down has not changed.
Where is the excess energy the lift provided the body?
(I am in 11th grade so please make your explanation simple enough for me to understand.) In both cases, the work provided by the elevator is turned into kinetic energy of the object.
In the moment the elevator stops (and stops doing work), the object thus carries kinetic energy and therefor will continue flying upwards. Both of your potential-energy calculations are therefore wrong - the actual top height will be more than $d$.
And the object will naturally reach higher in the second case since it gains a larger amount of kinetic energy in the second case, causing more potential energy to be stored.
In regular elevators you might feel various lifting forces without "flying" upwards as the elevator stops. So you might feel that the answer I provided is incorrect. But remember to include the decceleration as well. The larger lifting force in certain elevators might be exerted for a shorter time as well, with deceleration beginning before the stop is reached. In the ideal scenario of the elevator keeping a constant speed and then suddenly stopping immediately, then you will experience the "flying".
The following is multiple choice question (with options) to answer.
What has a positive impact on body strength? | [
"frequent physical contact",
"irregular body motion",
"decreased physical effort",
"active physical effort"
] | D | exercise has a positive impact on a body 's strength |
OpenBookQA | OpenBookQA-895 | mechanical-engineering, materials, automotive-engineering
Any time you've got a hot thing that needs to be cooled by convection, the limitation is the interface between the air and the object to be cooled. A thin copper plating -- or even making the whole rotor out of copper -- isn't going to help this.
The following is multiple choice question (with options) to answer.
A radiator is something that can | [
"recycle water from the toilet",
"propel a rocket to the moon",
"keep a room comfortable",
"filter water from the tap"
] | C | a radiator is a source of heat |
OpenBookQA | OpenBookQA-896 | thermodynamics, temperature, entropy, everyday-life
That's not a universal thing. That depends entirely on the room and the conditions.
But in your description, one big difference is solar heating. When the room cools, (assuming you don't have significant drafts), most of the heat loss will be via conduction through the walls and convection outside. Radiative losses occur as well, but they tend to be much smaller at room temperatures.
On the heating side, the same would be true for the shaded room on a hot day. But if the room isn't shaded, you add in radiative heating. The sun is (in some situations) simply able to deliver a lot more power to your room than your room would dump on mildly chilly day.
Besides the solar heating, it depends significantly on outside temps. Not sure what part of California you are, some places have common summer temps of 100F where you have nearly 30F difference over preferred temp. You mention a heat wave where it might be another 10F above that. It might be much rarer for that location to have a day that much below temp point (say ~44F). So you might be comparing 30F heating days to 18F cooling days.
Besides the outside, you might get heat transfer from other rooms. You said this room is on the second floor. Since heat tends to rise, you might benefit from any warmth in the room below, but not much from any cooling done there.
Finally, it might be a minor point in many places, but nothing running inside your home (except the A/C) is cooling it, and everything is heating it. The refrigerator, the oven, the water heater, the dryer, the big TV, all the occupants, etc are producing heat. For a small space (especially if you're cooking), that can make a difference.
The following is multiple choice question (with options) to answer.
What is least likely to exchange damage from heat with it's surroundings? | [
"A sheep",
"a car",
"A lake",
"A dead grove"
] | D | wood is an thermal energy insulator |
OpenBookQA | OpenBookQA-897 | homework-and-exercises, forces, energy
Title: Braking force required to allow bike to move down slope with an arbitrary constant velocity
Find the braking force required to allow a bike to move down a frictionless slope, inclined at $\theta$ radians above horizontal, with a constant velocity of v m/s.
I'm confused because Newton's 2nd Law of motion implies that the sum of forces on the bike must be zero in order for velocity to be constant, meaning that the braking force required is simply the bike's weight, resolved long the direction of the slope, in the opposite direction. But this only makes sure that velocity is constant.
How is it possible to apply a force to make the bike move with a constant velocity, of exactly v? My guess is that it has something to do with work, energy and power, but I haven't found a way yet. You are right that in this theoretical problem the breaking force to achieve constant velocity is the same for all velocities. You either stipulate that the bike has the desired speed as a initial condition, or that it coasts with no breaking applied until the desired velocity is reached.
In the real world, there will always be some friction or drag forces that are dependent on velocity, so for a real bike going down a real hill, there will be different breaking forces required to keep the bike at different speeds. Also there would be a human in the control loop adjusting the breaking pressure as needed to maintain the desired speed, probably without much conscious thought. These factors together make the answer to this problem seem unintuitive, but you have it right.
The following is multiple choice question (with options) to answer.
In order to assemble a bike, the following are needed with exception of? | [
"Nails",
"Bolts",
"Screws",
"Bars"
] | A | a bicycle contains screws |
OpenBookQA | OpenBookQA-898 | material-science, everyday-life
Title: Paper stiffness As piece of paper is folded and unfolded, the stiffness of the sheet may seem to be greatly increased.
To those of you who don't recognise it: take a sheet of A4 paper, grasp one of the edges and move your hand vertically. Now fold the paper in half, unfold it and repeat.
Is anyone aware of any formal or heuristic explanation of what changed? You have stiffened the paper by greatly increasing its bending moment of intertia. This can occur in at least two ways:
1.) When you unfolded the paper, it still had some residual bend which made the paper form a very shallow 'V'. Even though shallow. it is much deeper than the thickness of the original paper.
2.) When you unfolded the paper, it still had some residual bend which made the paper form a very shallow 'V' which was very localized to the area next to the bend. Even if you refold the paper in the opposite way, to take out or minimize the original fold, there is still a shallow 'V'. Even though it might be much shallower than in case 1, it is much deeper than the thickness of the original paper.
In both cases, the increased resistance to bending comes from the new geometry of the paper, more specifially, the geometry of a cross-section of the paper which goes through the bend.
Think of the unbent paper as a beam. Its resistance to bending is proportional to b(d^3), where 'b' is the width of the beam and 'd' is the depth. If you take a piece of 8.5" x 11" piece of paper and lay it flat over a pencil on the table, the paper will flop so that both ends touch the table. The paper forms a beam: 'b' is 8.5" or 11" (depending on how you laid the paper) and 'd' is the thickness of the sheet (say, about one one-hundreth of an inch).
How to improve the stiffness and strength of this beam? Fold the paper, accordion-style, with sharp 1/2" folds. Then lay it across the pencil, so that the folds are perdendicular to the pencil.
The following is multiple choice question (with options) to answer.
When we made some confetti it differed from the original sheets of paper in | [
"color",
"pattern",
"temperature",
"shape"
] | D | tearing an object changes that object 's shape |
OpenBookQA | OpenBookQA-899 | entomology, ant
Title: In an ant (or bee) colony, what is the very approximate ratio of new breeders to workers? For example, out of every 1000 eggs laid, X mature into drones and/or virgin queens. That seems impossibly precise but it illustrates the kind of number I want well. I'll accept answers for any species and any number of species, even one, with any amount of precision or lack thereof, because right now I can't even feel confident saying that there are more workers or more breeders, though I obviously suspect more workers.
I would also be ecstatic to have any live count just before the nuptial flight, i.e. for this colony in this study there were X workers, Y drones, and Z virgin queens just before the nuptial flight, or X workers and (Y+Z) breeders, or X% of the colony was breeders, or for this species on average X% are breeders just before the nuptial flight.
Anything. Any one thing and I can accept it as an answer.
I can find any number of studies that talk about the sex ratio between drones and virgin queens, so I know someone is counting. Maybe I'm not reading closely enough, but they always seem to slip away from giving all the numbers I need to figure this out for myself. So.
This answer is specific to the western honeybee, Apis mellifera, as there are massive amounts of data on them; more, possibly, than any other insect species. There has certainly been more data collected about them than any other hymenopteran.
At around the time of the nuptial flight, there may be as many as 60,000 workers in the hive, though likely number is more like 15,000 - 20,000. There will be either one (virgin) or two (one mated, one virgin) queens (the old queen will stay with the hive, if she is alive). There may be as many as 400 drones from the original colony (though usually the number is less, around 150 is typical; 10 - 50 of them will actually mate with the queen), and an equal number may join in the flight drawn from other colonies, especially in commercial beekeeping operations. Somewhere between 1000 - 6000 workers will take part in the nuptial flight with the virgin queen and the drones.
The following is multiple choice question (with options) to answer.
How many odorant receptors do honey bees have? | [
"4",
"270",
"170",
"70"
] | C | bees convert nectar into honey |
OpenBookQA | OpenBookQA-900 | homework-and-exercises, pressure
Title: Why is it difficult to cook food on mountains? Why is it difficult to cook food on mountains?
Is it because on increasing pressure boiling point of substance increase and on mountains there is less pressure so less boiling point. Then shouldn't it be easier to cook food on mountain.
I know that as we go to higher altitude there is less oxygen so it becomes difficult to cook. My teacher gave this question when she was teaching about boiling point and "How pressure effect boiling point?" so the reasoning should be of something about pressure. Why do we boil water to cook food? It's not actually because there's anything magic about the boiling of water, or that the physical process of boiling in particular does anything. Usually it's because we want a constant-temperature heat bath. Say you are boiling vegetables. You boil water, and you know that water is at 100 degrees. Water actually cannot get any hotter than this--it stays at that temperature or it becomes steam and leaves the pot. Then you put the vegetables into the boiling water, and therefore you know that they are in a 100 degree environment. Then, you know you need to leave them in there for however long--let's say five minutes.
Suppose, though, you were at high altitudes and water boiled at 95 degrees. Well, now when you put your vegetables into boiling water, they are only in a 95 degree environment, so the cooking time has changed. Your recipe no longer works correctly, and you will have to boil the food for longer.
Or maybe not, actually. The other possibility is that you are putting food in an oven, say something that's supposed to be 200 degrees. In this case, the water that's probably in the thing you're baking actually keeps the food cooler for longer. It reaches 100 degrees and will stay there until it boils off. However, if it boils off at 95 degrees, then again your cooking parameters will have changed. Since the water boils off faster, your dish spends more time at higher temperatures and can burn.
The following is multiple choice question (with options) to answer.
what makes food cooking possible? | [
"a temperature rise on it",
"the washing of it",
"the taste of it",
"none of these"
] | A | cooking food requires adding heat energy |
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