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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).
Feb
6
comment Does long term use of antibiotics in humans actually lead to a greater risk of infection?
Not usually in the individual, but in a population, improper antibiotic use can lead to resistant strains and more infections. Improper use usually means stopping therapy short and not using all the pills, using antibiotics for diseases they cannot help with, or very-long-term use in a healthy individual. Antibiotic resistance is basic a probability function, with the increase exposure to the antibiotics increasing the probability resistance will develop. Regimes are designed so that bacterial populations stay isolated/small and the chance for resistance remains small.
Jan
22
comment Is there any tree or other plant that produces a new crop in fast cycles?
@twelve -- I'd suggest something like gardening.stackexchange.com for people more knowledgeable than I. I'm a novice gardener, but from what I recall most people would need 2-3 basil plants to cover moderate to heavy use of the herb in their cooking from early spring through early fall (in climates where temperatures drop below freezing).
Jan
22
comment Is there any tree or other plant that produces a new crop in fast cycles?
Several harvests occur from most agricultural plants, most have 2-3 harvest periods per year, with a few exceptions. I'm not aware of any plant that produces a new crop every month; the closest I can think of would be herbs like Basil -- but that's because it produces continuously until it goes dormant.
Jan
22
comment True or false & fill in the blanks
@canadianer -- I agree, the nomenclature is pretty arbitrary and can be misleading. Thanks for bringing it up. :-)
Jan
22
comment True or false & fill in the blanks
@canadianer -- Yeah, but the nomenclature conventions make "polypeptides" to usually 3-5 peptides chained together. Before is "dipeptide" and after can get up to "oligilopeptide" IIRC.
Jan
18
comment how do macrophages have the capacity to digest pathogen in opsonization
There are multiple mechanisms to induce phagocytosis by macrophages. One includes B-cell antibodies (specifically the Fc region) and another includes chemokines emitted by local cells that can also induce phagocytosis. I do not have my material with me at the moment, but the short answer is: Macrophages can do both. They can eat pathogens without antibody stimulation, but antibodies can also stimulate them into action.
Jan
16
comment Father with mutated mtDNA- why isn't his offspring at risk?
@anongoodnurse "Paternal Inheritance of Mitochondrial DNA in Mice" - Nature 1991. The truth is that some paternal mtDNA is passed along, but the undergrad level generalization is that "no" paternal mtDNA is passed because the amount is practically non-existent outside of rare cases. In those rare cases then mtDNA can cause metabolic issues, like the 28 year old case study by Scwhartz in 2002.
Oct
2
comment How long does a signal from the brain take to reach the limbs?
@Christian - Roughly half, I'd assume. A full reflex arc is from a sensory neuron to the spinal column and back out to the muscles. The difference is probably due to length and the added junctions.
Oct
1
comment How long does a signal from the brain take to reach the limbs?
@shigeta - They're some overlap (the Vagus is a good example), but the function maps to the fiber type fairly well since space is the primary limiting factor for the peripheral system. However, I'll admit I haven't refreshed myself of the topic for a while, so it's possible the ratios are less strict than I believe.
Sep
25
comment What is a catalytic domain of an enzyme?
AFAIK MattDMo is correct. The catalytic site is the active site where the reaction takes place that triggers the conformation change. He is also correct about there being nearly infinite potential catalytic site designs.
Sep
7
comment Why do we absorb vitamins better from whole foods than from pills?
@user6035 - Yes, you could eat an artificial diet of macronutrients and micronutrients that would satisfy your biochemical needs. It would probably be "healthy" in that you would probably continue to live without issues you weren't already predisposed to. How other chemicals and compounds contribute to our health are unknown (think antioxidants), but have the potential to contribute significantly. However, please consult medical professionals for further info if you intend to pursue this. Due to genetic variation your body might have greater or lesser needs than the recommendations.
Aug
13
comment How does strength of a pulse related to EKG(ECG)?
Predict? I have no idea. I know V-tach and A-tach can be reasonably predicted by increasingly chaotic signals on an EKG, but I don't think the equipment would have the granularity to predict "strong" and "weak" beats.
Aug
13
comment What is the point of having evolved two nostrils?
I doubt it's so much that two nostrils are that much more beneficial than one as much as that most complex organisms follow bilateral symmetry for their body design. That said, your body will clog one and keep the other clear during fevers, allergies, or when it's cold to prevent it from drying out completely.
Jul
11
comment Why are men stronger than women?
@QuoraFeans - I re-answered the question to better fit what I think you're looking for.
Jul
5
comment Why are men stronger than women?
@pbond - If a woman performs strength training she will struggle to come even close to the weights the average male gym rat can lift (end quote) ::: Aside from very specific exercises (like the bench press), women only trail men by about 20% at Olympic levels. I guess that depends on your definition of "close", but rest assured if a woman chooses to take strength training seriously she definitely has the potential to outperform your average gym rat.
Jul
4
comment Why are men stronger than women?
@QuoraFeans - Then ask your question again, and be more precise. You're asking why the genders diverged in capacity for muscle development, and I answered that the theories involve Female-Selection for stronger men and that men acted as the defenders/hunters. What type of answer are you looking for?
Jul
4
comment Why are men stronger than women?
@QuoraFeans - You asked why women were weaker than men. The honest answer is that men only have more capacity for strength and potential for muscle mass - but most men will never use it, and it's cultural for women to want to be thin (which might be a minor influence of male-choice selection) - but both women and men are capable of being strong with training. If you're that unhappy with the answer, ask again with more specifics and I will try to answer again.