Final answer:
Animals perform respiration to facilitate cellular respiration, which provides energy for cellular functions by breaking down glucose using oxygen to produce ATP, carbon dioxide, and water. The answer is option D.
Step-by-step explanation:
Animals are required to do respiration primarily because of the process of cellular respiration that occurs in the cells of their bodies. This intracellular process breaks down glucose with oxygen to produce carbon dioxide and energy in the form of ATP molecules, which are essential for powering numerous cellular activities.
The glucose needed for cellular respiration comes from the digestive system, and the oxygen required for the process is obtained through the respiratory system, both of which are transported by the cardiovascular system. In contrast, the carbon dioxide produced as a byproduct of cellular respiration is expelled from the body through the respiratory system.
It's important to distinguish between cellular respiration, which is a metabolic process, and respiration by the respiratory system, which involves gas exchange with the outside environment. While cellular respiration uses oxygen and releases carbon dioxide, the respiratory system provides the oxygen needed for this process and removes the carbon dioxide generated.