Answer:
B. oxygen, glucose
Cellular respiration is a complex process by which cells break down glucose molecules to produce energy in the form of ATP (adenosine triphosphate). The process involves three main stages: glycolysis, the Krebs cycle, and oxidative phosphorylation.
The process begins with molecules of glucose, which are broken down during glycolysis. This stage takes place in the cytoplasm of the cell and does not require oxygen. Glucose is broken down into two molecules of pyruvate, and energy in the form of ATP and NADH is produced.
The second stage, the Krebs cycle, takes place in the mitochondria of the cell and requires oxygen. Pyruvate is converted into acetyl-CoA, which enters the Krebs cycle. During this stage, acetyl-CoA is broken down into carbon dioxide, ATP, and electron carriers like NADH and FADH2.
The final stage of cellular respiration is oxidative phosphorylation, which also takes place in the mitochondria. During this stage, NADH and FADH2 produced during the first two stages are used to produce a large amount of ATP through a process called the electron transport chain. Oxygen is used as the final electron acceptor, and water is produced as a byproduct.
Overall, cellular respiration is an essential process for all living organisms, as it provides the necessary energy for various cellular activities. It begins with glucose molecules, which are broken down in a series of steps to produce ATP, carbon dioxide, and water.