Question

multiple choice question
when will a human cell produce lactic acid from pyruvic acid and nadh?
if there is too much oxygen available
if carbon dioxide levels increase in the cell
at all times (pyruvic acid is always converted to lactic acid in human cells)
if there is not enough oxygen available
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Explanation:

In human cells, when oxygen is insufficient, pyruvic acid is converted to lactic acid through a process called lactic - acid fermentation. This occurs to regenerate NAD+ so that glycolysis can continue to produce ATP. When there is enough oxygen, pyruvic acid enters the mitochondria and is further oxidized in the citric acid cycle. Carbon dioxide levels do not directly trigger this conversion to lactic acid, and pyruvic acid is not always converted to lactic acid in human cells.

Answer:

If there is not enough oxygen available