The set point is the normal, or target, value for something.
A single molecule is the one that is responsible for initiating a signal transduction pathway. The answer in this question is a single molecule. Molecule is defined as an electrically neutral group of two atoms or more held together by a chemical bonds.
I'm 99 percent sure that the answer is replication. Hope it helps!
A certain process called photosythesis i think
8:C
9: A
10: B
11: C
12: B
13: A
14: B
15: A