Question

In the absence of oxygen (^O2), the partial metabolism of glucose in human muscles produces _____.

a) Lactic acid
b) Pyruvate
c) Carbon dioxide
d) Ethanol

Answer 1

In the absence of oxygen, human muscles produce lactic acid from the partial metabolism of glucose through anaerobic respiration, a process critical for the continuation of ATP production.

Step-by-step explanation:

In the absence of oxygen (O2), the partial metabolism of glucose in human muscles produces lactic acid. This process, known as anaerobic respiration or fermentation, allows for the continuation of ATP production when oxygen supply is low or nonexistent. Pyruvate, the product of glycolysis, is converted into lactic acid, which then serves as the final electron acceptor. This conversion is crucial as it regenerates NAD+, which is essential for glycolysis to proceed. The lactic acid produced can lead to muscle fatigue but is transported to the liver, where it can be converted back into pyruvate or glucose through the Cori cycle.