The process by which some organisms oxidize inorganic compounds to obtain energy is known as

Step 1: Analyze the question The question asks for the process in which some organisms (certain bacteria) oxidize inorganic compounds to get energy. The key phrases are "some organisms," "oxidize inorganic compounds," and "obtain energy."

Step 2: Explain the concept Chemosynthesis is a form of autotrophic nutrition. Instead of using light, as in photosynthesis, chemosynthetic organisms use energy released from oxidizing inorganic substances to make their own food (carbohydrates) from carbon dioxide and water.

Examples in Nigerian syllabuses:

• Nitrosomonas oxidizes ammonia to nitrites.
• Nitrobacter oxidizes nitrites to nitrates.
• Sulphur bacteria oxidize hydrogen sulphide to sulphur.
• Iron bacteria oxidize iron(II) compounds to iron(III).

Step 3: Check each option

• A. Catabolism: the breakdown of complex molecules to release energy. It is general and does not specifically involve inorganic compounds.
• B. Chemosynthesis: energy is obtained by oxidizing inorganic compounds. This matches the question.
• C. Glycolysis: the breakdown of glucose to pyruvate in the cytoplasm. Glucose is organic, so this does not fit.
• D. Metabolism: the sum of all chemical reactions in an organism. It is too general.
• E. Photosynthesis: uses light energy, not the oxidation of inorganic compounds.

Step 4: Answer The correct option is **B.

Exam tip: Match the prefix to the energy source. Photo- means light, and chemo- means chemicals. If a question mentions bacteria oxidizing ammonia, nitrites, sulphur, or iron, think chemosynthesis.