Which of the following statements about sulfur-oxidizing prokaryotes is FALSE?

• A. They use sulfur compounds as their sole carbon source.
• B. Some sulfur-oxidizing prokaryotes can form sulfur granules inside their cells.
• C. They play a role in the biogeochemical cycling of sulfur.
• D. They obtain energy by oxidizing reduced sulfur compounds such as H2S.

Answer: (A)

Verified step by step guidance

1. Understand the metabolic characteristics of sulfur-oxidizing prokaryotes: these organisms obtain energy by oxidizing reduced sulfur compounds such as hydrogen sulfide (H\_2S), thiosulfate, or elemental sulfur.
2. Recognize that sulfur-oxidizing prokaryotes are chemolithoautotrophs, meaning they use inorganic compounds (like sulfur compounds) as an energy source but fix carbon dioxide (CO\_2) as their carbon source, not sulfur compounds.
3. Note that some sulfur-oxidizing prokaryotes can accumulate sulfur granules inside their cells as intermediate storage during the oxidation process.
4. Recall that these organisms play an important role in the biogeochemical cycling of sulfur by converting reduced sulfur compounds into sulfate, which can be used by other organisms or returned to the environment.
5. Identify the false statement by comparing each option to these known facts: the statement claiming they use sulfur compounds as their sole carbon source is false because their carbon source is typically CO\_2, not sulfur compounds.