An is a drug that mimics or increases a neurotransmitter's effects, whereas an is a drug that blocks a neurotransmitter's effects.

Ecology can best be described as the study of what

Compare the parts of a cell and the cell as a whole to another common nonliving system (i.e., a car, a city, describe the parts of a cell and their primary function.

Identify the structure in organisms that do not have kidneys that is adapted to regulate water balance