Question

When oxygen supply is limited, cells will undergo:

a) Anaerobic respiration.
b) Cell death or apoptosis.
c) Increased lactic acid production.
d) Reduction in energy production through oxidative phosphorylation.

Answer 1

Cells undergo anaerobic respiration when oxygen is scarce, converting pyruvate to lactic acid and producing a limited amount of ATP through glycolysis, a process necessary for vital activities and intense physical exertion.

Step-by-step explanation:

When oxygen supply is limited, cells will undergo anaerobic respiration. This process involves pyruvate entering a pathway where it can be converted into lactic acid, which serves to keep glycolysis ongoing. This pathway, also known as fermentation, enables ATP production under low oxygen conditions by generating an additional ATP and reducing NADH back to NAD*, essential for glycolysis to proceed.

However, this method yields less ATP compared to aerobic respiration, with a net gain of only two ATP molecules from glycolysis. Red blood cells, or erythrocytes, rely exclusively on this process due to the absence of mitochondria. Additionally, during intense exercise, muscles also resort to this form of respiration to maintain ATP levels when oxygen delivery is insufficient.