As par of human microbiota, many bacteria live in our intestines. Do the live only in the small intestine, or only in the large intestine, or both equally? Online sources are super-contradicting!

Following a severe bleeding the production of urine decreases. This is most likely because of...
A. lowered blood pressure.
B. a rectricted blood supply to the kidneys.

Which one is true? Please elaborate the answer. Thank you so much for your input in advance!

Someone please explain me the difference between the aforementioned organelles, e.g. which ones are membrane enclosed, exclusive to prokaryotes or eukaryotes. I came across the expression "unit membrane" in regards to this problem, what does that mean?

What mechanism causes heart muscle cells occasionally to have multiple nuclei? Is that the same blast-fusion mechanism that forms syncytium of skeletal muscle cells? And the same question goes for all multinucleated cells in the human...

Related question:

I've read the word somewhere "pulverisation" to describe degradation of host DNA upon exposure of viral nucleic acid, but when and how does that happen? Is that an accepted and a well established technical term?

"active transport does not have to go against conc. gradient, theoretically." My question is related to that: In action potential, right after depolarization, does Na+/K+ pump keep moving sodium out and potassium in? Than it would move those ions down their gradient (!?), still at the expense of ATP...

Cyclic photophosphorylation vs. Non-cyclic photophosphorylation Which organisms use which mechanism? I've been looking for the answer but couldn't find a reliable one, most answers are very vague. If the organism has both PSI and PSII, it can readily switch between cyclic and non-cyclic, depending o...

I'm still keen to know more, please.

I thought roan meant two two hair colors are expressed simultaneously (e.g. black and white hair), instead of grey hair. But then I wouldn't understand, each heterozygous cell would grow multiple hairs? Just don't get it...

I know that lactic acid fermentation is possible in muscle cells and mature red blood cells. My questions would be 1) all muscle cell types are able to perform lactic acid fermentation? 2) is there any other type of fermentation that a human cell (!) is able to perform in the body?

Will that boost ATP production in mitochondria? Or other reactions are rate limiting?

Are they produced by RER-bound ribosomes or by free ribosomes and later they get imported into the SER. Also, how does the ER separate enzymes that work in the RER (e.g. glycosylases) from enzymes that work in the SER (e.g. detoxifying enzymes)? I know sometimes the ER is "mixed" so could be conside...