Which two activities provide the reactants for cellular respiration?

A. releasing air and exercising

B. breathing in air and exercising

C. releasing air and eating food

D. breathing in air and eating food

The best answer is D.

The food that is eaten will be digested and broken down into its simplest molecules or monomers. Carbohydrates, the biggest source of energy for the body, are broken down into their monomer which is glucose. Cells of the body take in glucose and break it down during the process of cellular respiration to provide energy. This happens in the glycolysis, the first stage of respiration.

Breathing in air provides the body cells with oxygen which is used in the last stage of respiration namely the electron transport chain where it acts as the final electron acceptor, thus completing this stage which yields 34 molecules of ATP from every single glucose molecule.