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2d
comment Is “A” inhibiting “B” and vice-versa, a positive feedback loop?
@Kelvin -- I don't think there's much room to disagree. In the context of Biology a Positive Feedback Loop has a distinct definition; an increase in A leads to an increase in B, whose product or byproduct leads to an increase in A in an (IIRC) exponential fashion until a limiting factor is involved.
Jan
27
comment How is HIV evolutionarily viable despite its extreme virulence?
@Anonstudent You might be thinking of the rate of mortality or pathogenecity (rate an infection causes a disease) -- which also aren't always selected against. There are many niches to fill between the extremes.
Oct
9
comment Can we change one's genome into the genome of somebody else
No, that would be practically impossible with modern technology. The explanation is pretty lengthy, but do you have specific questions or a certain method you were thinking of that could be more concretely addressed?
Oct
1
comment Why can't we use plasmids to add genes to ourselves?
IIRC humans have several mechanisms that digest extra-nuclear DNA. Unfortunately I don't have a reference handy, but I'm 95% sure any plasmid would just be destroyed.
Sep
23
comment How do we perceive acceleration?
@Dexter -- The doppler effect comes into play with echoes made by your bike's motor, too, and other sounds as you passed by their origins.
Sep
23
comment How do we perceive acceleration?
@AliceD - "the endolympth and otoliths..." I specified both. The otoliths are partially responsible. The vestibular system is designed to track 3-axial movement (XYZ), and the frequency of action potentials changes depending on how many hairs are open and how "open" they are. Unless I'm very, very incorrect, the vestibular system tracks acceleration in addition to vector.
Sep
22
comment How do we perceive acceleration?
@Dexter -- The doppler effect is the change in pitch of a sound due to the velocity of its source. If the source of a noise is moving, the sound waves in the direction of its velocity/acceleration are condensed (higher pitched), and those in the opposing direction are elongated (lower pitch). You can tell if something is heading towards or away based on that. A classic example are race cars or racing bikes, whose engine noises change pitch to an observer despite constant speeds: youtube.com/watch?v=qyxvPiOqEiE
Sep
21
comment Why are there so many different humans yet chimpanzees are just chimpanzees?
Could you re-phrase your question? Are you asking why we don't find/identify more fossils of Pan ancestors?
Sep
21
comment Why are there so many different humans yet chimpanzees are just chimpanzees?
The rest you listed that are not Homo sapiens are evolutionary ancestors of humans. Not humans. Close to humans? Sure, some of them. But not humans.
Sep
18
comment How do I offer a generous gift to sweet-seeking wasps, bees, hornets, bumble-bees?
So... you're looking for something you can have on-hand that will entice wasps and bees to follow it so you don't have to swat at them?
Sep
8
comment Can the third sex be categorized as Male or Female?
@Remi.b -- The missing SRY gene in a phenotypical male with XX chromosomes is a really interesting exception to the general rule I described above. Thanks for bringing it up in the comments! I didn't know it existed.
Sep
3
comment What kind of larvae are these?
Not a bug guy, but it does look like termites.
Jul
25
comment Do the enzymes and compounds in saliva help with stain removal?
Amylase doesn't break down proteins. It breaks down amylopectin -- a type of starch (sugar) molecule. Proteins are broken down by proteases (not found in saliva or semen), and many available stain removers use proteases.
Jul
7
comment Is the immune system suppressed during sleep?
I don't have the time for a full answer, so I may come back, but generally 'no'. There is a difference between hibernation (a reduction in metabolic rate to survive prolonged periods of fasting) and sleeping. Humans do not hibernate, and when we are asleep the body doesn't try to save energy. Our brains go through REM sleep, which is just as active as waking hours, our organs -- especially dermal and muscle tissues -- amp-up their repair mechanisms while sleeping. Given that prolonged poor and/or lack of sleep significantly lengthens illnesses, the immune system should be very active.
May
15
comment What are the side-effects of long-term liquid breathing?
@HDE226868 -- One thing that absolutely must be said that wasn't addressed is this: All of those human studies used external pumps to move the fluid. Mammalian diaphragms are not designed to move a liquid medium more than a handful of times. They will literally tear themselves to shreds very, very quickly.
May
13
comment What recovers normal polarisation after hyperpolarisation?
Can't give a full comment at the moment, but... Na+ and K+ have different electrochemical equilibriums, and in addition to the Sodium-Potassium Pump there are many porins that act as passive diffusion routes to re-establish the cell's preferred equilibrium.
Apr
29
comment Do we have fundamental conflict in biology?
@Remi.b -- More cells = more cell divisions required in the first place. Whale cells are not orders of magnitude larger than humans, despite being orders of magnitude larger as an organism. Since the vast majority of cells have some turnover, having more could also mean a hire rate of division even if the time it takes is higher. Peto's paradox looks fine (to me), but it does point out that DNA mutations do not always result in cancer. An extra stop-check prior to cell division seems to have a tremendous effect on cancers if you look at Naked Mole Rats. ;-)
Apr
19
comment Why did the Brain develop in the front in most organisms?
@aandreev -- They co-evolved. As brains became more complex and bigger, there needed to be a better place to store them. Thick bones aren't very spacious. Hollow bones aren't very protective. The compromise for organisms evolving a larger brain was the skull: A hollow, encapsulating bone that can also be very dense (especially among goats, bovines, etc.). It's also a design that means there's only one area to protect instead of every single thick bone in your body.
Apr
4
comment Core Biological concepts explained to a Computer Scientist?
@poka.nandor Thanks. :-)
Feb
25
comment Baby birds hair and mammal hair is a convergent evolution?
Fledglings do not have hair, but "down" -- a very, very fine type of feather used to insulate the chicks (and convergent in purpose with mammalian hair there).