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Multiple Choice
Which of the following are the main products of the electron transport chain (ETC) in cellular respiration?
A
ATP, H$_2$O, and NAD$^+$
B
Glucose, O$_2$, and NADH
C
CO$_2$, ATP, and FADH$_2$
D
Pyruvate, CO$_2$, and ATP
Verified step by step guidance
1
Step 1: Understand the role of the electron transport chain (ETC) in cellular respiration. The ETC is the final stage of aerobic respiration, located in the inner mitochondrial membrane, where electrons are transferred through a series of protein complexes to ultimately produce ATP.
Step 2: Recall the inputs to the ETC. Electrons are donated by NADH and FADH$_2$, which are generated during earlier stages of cellular respiration (glycolysis, pyruvate oxidation, and the citric acid cycle). Oxygen (O$_2$) acts as the final electron acceptor.
Step 3: Identify the main products of the ETC. As electrons move through the chain, a proton gradient is established across the mitochondrial membrane, driving ATP synthesis via ATP synthase. Water (H$_2$O) is formed when oxygen combines with electrons and protons. NAD$^+$ is regenerated as NADH donates electrons to the chain.
Step 4: Eliminate incorrect options based on the products of the ETC. Glucose is not produced in the ETC; it is broken down during glycolysis. CO$_2$ is released during earlier stages, not the ETC. Pyruvate is an intermediate in glycolysis, not a product of the ETC.
Step 5: Conclude that the correct answer is ATP, H$_2$O, and NAD$^+$, as these are the main products of the electron transport chain in cellular respiration.