Answer:
Excess nitrogen can cause over-stimulation of growth of aquatic plants and algae. Excessive growth of these organisms, in turn, can clog water intakes, use up dissolved oxygen as they decompose, and block light to deeper waters. So few organisms live in these conditions or even can suffocate and die.
Answer:
Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins.
Explanation:
From Wikipedia
I think its called an Axon.
Hypothesis is what you think will happen before the experiment, it isn't necessarily backed up by any sources or evidence. A scientific law is the observation of a phenomenon and a theory is the explanation both can be used together to back each other up.