Questions: 4.2.2 Quiz: Respiration Introduction Question 7 of 10 Which process in respiration happens first? A. Glycolysis B. Krebs cycle C. Electron transport chain D. Pyruvate processing

The answer is the first one (or A): Glycolysis.

Explanation for each option: A. Glycolysis - Correct. Glycolysis is the first step in the process of cellular respiration. It occurs in the cytoplasm of the cell and involves the breakdown of glucose into two molecules of pyruvate, producing a small amount of ATP and NADH in the process.

B. Krebs cycle - Incorrect. The Krebs cycle, also known as the citric acid cycle or TCA cycle, occurs after glycolysis and pyruvate processing. It takes place in the mitochondria and further breaks down the products of glycolysis to produce ATP, NADH, and FADH2.

C. Electron transport chain - Incorrect. The electron transport chain is the final stage of cellular respiration. It occurs in the inner mitochondrial membrane and uses the electrons from NADH and FADH2 to produce a large amount of ATP through oxidative phosphorylation.

D. Pyruvate processing - Incorrect. Pyruvate processing, also known as the link reaction or pyruvate decarboxylation, occurs after glycolysis. It converts pyruvate into acetyl-CoA, which then enters the Krebs cycle.

Summary: The first process in respiration is Glycolysis.