What organisms always form the base of an energy pyramid (or to be listed in food chains)? Why are they in that position?

What would happen to the nutrients in an ecosystem if decomposers, such as bacteria, didn’t exist there?

Growth of chest hair, deepening of the voice, and muscle growth are secondary sex characteristics. which most likely affects the development of these traits? testes ovaries prostate gland vulva

Crossing over is a method of (blank)?