Oxygen concentration generally plays an important role in regulating respiration:

A) all the time.
B) never.
C) only when the carbon dioxide concentration falls markedly.
D) only when the oxygen concentration falls markedly.
E) only when the pH falls markedly.

Oxygen Concentration

The amount of oxygen present in a given environment, important for various biological and chemical processes.

Respiratory Rate

The rate at which breathing occurs, typically measured in breaths per minute.

Carbon Dioxide

An odor-free, colorless gas created by the burning of carbon and organic substances, as well as by the process of respiration, which is absorbed by plants for photosynthesis.