Apentix/AP Biology/Unit 3: Cellular Energetics/Question
AP Biologyeasymcq1 pt

Why do hard-working muscle cells convert pyruvate to lactate under low-oxygen conditions?

A.To regenerate NAD+ from NADH so glycolysis can keep producing ATP
B.Because lactate production directly generates large amounts of ATP
C.To eliminate surplus NAD+ that accumulates during exercise
D.To convert lactate into fresh glucose inside the same muscle fiber

Explanation

Core Concept

Glycolysis requires NAD+ as an electron acceptor. Converting pyruvate to lactate oxidizes NADH back to NAD+, allowing glycolysis to continue producing ATP when respiratory oxidation of NADH cannot keep pace with glycolytic demand. Fermentation itself adds no ATP beyond glycolysis, and its use should not be reduced to the claim that oxygen simply 'cannot accept electrons fast enough.'

Correct Answer

ATo regenerate NAD+ from NADH so glycolysis can keep producing ATP

More Unit 3: Cellular Energetics practice questions

Try a random question →

Practice more AP Biology questions with full explanations

Practice Unit 3: Cellular Energetics Questions →