Question

multiple choice question

which is the primary pathway used by heterotrophic microorganisms to obtain energy?

aerobic respiration
fermentation
anaerobic respiration

Explanation:

Identify the metabolic strategies of heterotrophs

Heterotrophic microorganisms obtain energy by breaking down organic compounds. The three primary pathways used are aerobic respiration, anaerobic respiration, and fermentation.

Compare energy yields of the pathways

• Aerobic respiration: Yields the highest amount of ATP (typically 36–38 ATP per glucose molecule) using oxygen as the final electron acceptor.
• Anaerobic respiration: Yields less ATP than aerobic respiration, using non-oxygen inorganic molecules as final electron acceptors.
• Fermentation: Yields the lowest amount of ATP (2 ATP per glucose molecule) via substrate-level phosphorylation without an electron transport chain.

Determine the primary pathway

Because aerobic respiration provides the highest energy yield and is the most widespread and efficient metabolic pathway among heterotrophic organisms in oxygen-containing environments, it is considered the primary pathway for energy acquisition.

Answer:

• Aerobic respiration (Correct answer)
• Fermentation
• Anaerobic respiration