GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Other Metabolic Processes

Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology

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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

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Example Questions

Example Question #1 : Help With Other Metabolic Processes

What is the primary purpose of fermentation?

Possible Answers:

Generate ethanol

Generate ATP

Regenerate NAD+

Generate oxygen

Correct answer:

Regenerate NAD+

Explanation:

The primary purpose of fermentation is to regenerate the NAD+ that was reduced to NADH during glycolysis. This is essential because the cell will need that NAD+ to be able to go through glycolysis. In anaerobic environments, the Krebs cycle and electron transport chain cease to function, leaving glycolysis as the primary metabolic process for the cell to generate ATP. NAD+ is an essential reactant for glycolysis, but is rapidly consumed when the electron transport chain is not running. Fermentation takes place in order to replenish this reactant and allow glycolysis to continue.

Ethanol and lactic acid can be products of fermentation, but are not the primary purpose for fermentation. No oxygen or ATP is generated during this process.

Example Question #1 : Help With Other Metabolic Processes

In comparison to anaerobic metabolism, aerobic metabolism of glucose produces __________.

Possible Answers:

more oxidized coenzymes

fewer protons for pumping in mitochondria

less carbon dioxide

pyruvate

more ATP per glucose

Correct answer:

more ATP per glucose

Explanation:

During aerobic metabolism, a single glucose molecule produces significantly more ATP molecules than during anaerobic metabolism. The exact number depends on a number of things, including the organism, cell type, and NADH shuttle. Aerobic metabolism of glucose produces more reduced coenzymes, which drop off their electrons at the electron transport chain in the mitochondria. Electron transport provides energy to pump protons from the mitochondrial matrix into the intermembrane space. Both processes produce pyruvate.

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept
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