Given a scientific question, generate a correct answer to it.

Input: Consider Input: What is the term for a substance that increases the rate of a chemical reaction but is not changed or used up in the reaction?

Output: a catalyst

Input: Consider Input: What causes continents to drift closer to the poles or the equator?

Output: plate movements

Input: Consider Input: What important function do bees perform on garden plants and many commercial fruit trees?
Output: pollination