Question

after glycolysis, the pyruvate molecules can follow two different metabolic routes: aerobic and anaerobic respiration. what is the main difference between these?
a) anaerobic respiration does not occur in mammalian cells
b) they are the same metabolic pathway, occurring in different locations
c) aerobic respiration occurs in the presence of oxygen and anaerobic respiration is inhibited in its presence
d) anaerobic respiration does not need oxygen to occur and aerobic respiration does

Explanation:

• Option a is incorrect: Mammalian cells (e.g., muscle cells) perform anaerobic respiration (lactic acid fermentation) during oxygen deprivation.
• Option b is incorrect: They are distinct metabolic pathways with different end products and energy yields, not just different locations.
• Option c is incorrect: While aerobic respiration requires oxygen, anaerobic respiration is not just "inhibited" by oxygen; it is a pathway that functions in the absence of oxygen entirely.
• Option d correctly identifies the core difference: Aerobic respiration depends on oxygen as the final electron acceptor, while anaerobic respiration proceeds without oxygen, using alternative electron acceptors.

Answer:

d) Anaerobic respiration does not need oxygen to occur and aerobic respiration does