Apentix/AP Biology/Unit 3: Cellular Energetics/Question
AP Biologyhardmcq1 pt

Why does glycolysis supported by fermentation capture much less ATP per glucose than aerobic respiration?

A.Ethanol synthesis consumes twenty-eight ATP per glucose, canceling most of the gross yield
B.Without oxygen, glycolysis loses its payoff phase and keeps only the two ATP of the investment phase
C.Anaerobic cells burn two ATP per glucose importing scarce oxygen equivalents from their surroundings
D.Fermentation itself nets zero ATP, so with the electron transport chain stalled the cell keeps only glycolysis's substrate-level phosphorylation while most energy stays locked in ethanol

Explanation

Core Concept

Fermentation regenerates NAD+ so glycolysis can continue, but it does not use oxidative phosphorylation to harvest most of the remaining chemical energy in glucose-derived molecules. Aerobic respiration therefore captures substantially more ATP per glucose. Exact ATP totals vary with cellular conditions and are not necessary for the AP-core concept.

Correct Answer

DFermentation itself nets zero ATP, so with the electron transport chain stalled the cell keeps only glycolysis's substrate-level phosphorylation while most energy stays locked in ethanol

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