Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Problem:Passage: Keeping the rate of metabolism high takes a constant and plentiful supply of oxygen. That's because cellular respiration, which produces energy, requires oxygen. The lungs and heart of mammals are adapted to meet their oxygen needs. Answer: metabolism
Solution:
A constant and plentiful supply of oxygen is required in order to maintain a high rate of what?