Cellular respiration is a set of metabolic reactions that take place in the cells of organisms to convert biochemical energy from nutrients into adenosine triphosphate (ATP), and then release waste products. This process is essential for the survival of all living organisms because ATP serves as the main energy currency for cells. During cellular respiration, several substances are consumed:

1. Glucose (or other organic molecules): Glucose is a simple sugar that is commonly used as the primary source of energy during cellular respiration. It is broken down into smaller molecules to release stored chemical energy.

2. Oxygen: Oxygen is an essential reactant in cellular respiration. It is used as the final electron acceptor in the electron transport chain, which is the last stage of cellular respiration.

3. ATP: A small amount of ATP is consumed at the beginning of cellular respiration to activate glucose molecules and initiate the glycolysis process.

4. NAD+ (Nicotinamide Adenine Dinucleotide): NAD+ is an important coenzyme that accepts electrons and protons during glycolysis and the citric acid cycle (also known as the Krebs cycle). As a result, it gets reduced to NADH, which is an electron carrier.

5. FAD (Flavin Adenine Dinucleotide): Similar to NAD+, FAD is another coenzyme that accepts electrons and protons during cellular respiration. It is reduced to FADH2, which also functions as an electron carrier.

6. Water: Water is involved in several steps of cellular respiration, particularly in the citric acid cycle. It provides hydrogen ions (H+) for the electron transport chain and is a product of oxidative phosphorylation.

In summary, during cellular respiration, glucose, oxygen, ATP, NAD+, FAD, and water are consumed to produce energy in the form of ATP, release carbon dioxide and water as waste products, and generate reduced coenzymes (NADH and FADH2) that participate in the electron transport chain.