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1500 questions
28
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4 answers
Where does the 'C' in exhaled CO₂ mostly come from?
When a human being exhales CO₂, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of where carbon atoms breathed out in the form of CO₂…
mring
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How long does antibiotic-dosed LB maintain good selection?
Various people in our lab will prepare a liter or so of LB, add kanamycin to 25-37 mg/L for selection, and store it at 4 °C for minipreps or other small cultures (where dosing straight LB with a 1000X stock is troublesome). Some think using it…
Nick T
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28
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2 answers
What determines which strand of DNA is transcribed by RNA polymerase?
DNA has two strands. How does the machinery of RNA transcription determine which one to transcribe?
CognisMantis
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Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle
Why is the Krebs cycle considered a part of aerobic metabolism if molecular oxygen is not involved in any of the reactions in the cycle?
I originally thought that Krebs cycle was aerobic metabolism because it is in the process that oxygen is the…
bobb
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2 answers
Why does looking at bright light trigger sneezing in some people?
Why does looking at bright light trigger sneezing in some people?
Are there any recent studies that have found a cause for this Photic sneeze reflex? The Wikipedia article only references studies pertaining to the effect, stating that the cause is…
luvieere
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Is there any use of CO₂ in human body?
We all know CO₂ as a waste product of metabolism . Does CO₂ have any helpful role , apart from having a role in pH of blood ?
biogirl
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What is this strange sea creature we found on the beach?
We found this on a beach in North Devon, UK. I've never seen anything like it.
There's a yellowy-ball in the middle with 5 pointed shells attached to it, each of which seems to have a single "leg" coming out of the bottom. It almost looks like it's…
SystemParadox
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Is the Common Cold an Immune Overreaction?
It's my understanding that the majority of symptoms associated with the common cold (runny nose, inflamed sinus, slight fever) are essentially the result of the immune system's response.
I've never heard of someone dying of the common cold (unlike…
ScottishTapWater
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How many people are required to maintain genetic diversity?
Imagine humans were to colonize a distant planet and it was a single one-way trip. How many people would they need to bring?
Obviously 2 is the minimum, but that would result in a lot of inbreeding.
So what number is the minimum number of people you…
cdmckay
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Does the octopus have an anus? What does it look like?
Octopuses are cephalopods, which have separate anal and oral openings. Indeed, descriptions of the cephalopod GI tract clearly depict an anal opening.
However, I am very confused about how this applies to the octopus. I don't think I've ever seen…
Superbest
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Why haven't prey evolved the ability to always outrun their predators?
I can understand why some prey can't outrun a recently evolved species. However, since cheetahs have existed for so long, why haven't its prey evolved to always outrun it, driving cheetahs to extinction. Is it because the cheetah population size is…
Timothy
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Why is water flavorless?
I read recently that humans have an innate preference for sweet-tasting foods. That seems feasible since carbohydrates are necessary for cells to undergo cellular respiration, but why then is water not similarly good-tasting? The thirst mechanism is…
ringo
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Why are there no known animals with an odd number of legs?
In my 6th grade science book it is said that there are no three legged animals, and that no animal with an odd number of limbs exists. I checked Wikipedia and could confirm this:
There are no known naturally occurring three-legged animals
On…
user31782
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Why do vaccines cause your arm to hurt?
When you get a shot for a vaccine (for example, the annual flu vaccine), the nurse frequently indicates that your arm will ache for a day or two, maybe more. This ache is typically not just a pain from having your skin punctured, but is actually an…
Kate Bertelsen
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27
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1 answer
What is this droplet of liquid that comes out of a mosquito?
I have been looking at pictures of different species of mosquito and several times I came across pictures where the mosquito seems to be secreting some kind of fluid.
In the pictures one can clearly see that the mosquito both secretes transparent…
user14636