A strictly fermentative bacterium produces energy primarily by which of the following processes?

• A. Oxidative phosphorylation using an electron transport chain
• B. Direct oxidation of fatty acids
• C. Substrate-level phosphorylation during glycolysis
• D. Photophosphorylation in the presence of light

Answer: (C)

Verified step by step guidance

1. Understand the metabolic characteristics of a strictly fermentative bacterium: such bacteria generate energy without using an electron transport chain or oxygen as the final electron acceptor.
2. Recall that oxidative phosphorylation requires an electron transport chain and a proton gradient, which strictly fermentative bacteria do not use because they do not perform respiration.
3. Recognize that direct oxidation of fatty acids is a process linked to aerobic or anaerobic respiration, not fermentation.
4. Identify that photophosphorylation occurs in photosynthetic organisms using light energy, which is unrelated to strictly fermentative bacteria.
5. Conclude that strictly fermentative bacteria produce ATP primarily through substrate-level phosphorylation during glycolysis, where a phosphate group is directly transferred to ADP to form ATP.