Given a scientific passage and an answer, generate a question for the given answer.

Passage: Most chemical reactions in organisms take place in an environment that is mostly water. Answer: water
The environment where most chemical reactions in organisms takes place consists mostly of what?

Passage: Excretion is the process of removing wastes and excess water from the body. It is one of the major ways the body maintains homeostasis. Organs of excretion make up the excretory system. They include the kidneys, large intestine, liver, skin, and lungs. Answer: excretion
What is the process of removing wastes and excess water from the body?

Passage: behind the mirror. Convex mirrors diverge light rays and, thus, have a negative focal length. Answer: convex
What mirrors diverge light rays and, thus, have a negative focal length?