Which organisms make food by chemical reactions using energy from chemical bonds rather than light?

• A. Heterotrophic Bacteria
• B. Chemosynthetic Bacteria
• C. Photoautotrophic Bacteria
• D. Saprotrophic Fungi

Answer: (C)

Organisms that make their own organic food using energy released from chemical reactions rather than from light are chemoautotrophs, or chemosynthetic organisms. They obtain energy by oxidizing inorganic molecules (like hydrogen sulfide or ammonia) and use that energy to fix carbon dioxide into organic compounds. This is different from light-driven photosynthesis, which powers photoautotrophs, and from heterotrophs or saprotrophs that rely on pre‑formed organic matter for both energy and carbon. Among the options, chemosynthetic bacteria fit this idea best, since they build organic molecules using energy from chemical bonds in inorganic substances.