Autotrophic nutrition is a process whereby an organism obtains food

Step 1: Analyze the question The question asks for the definition of autotrophic nutrition.

Step 2: Explain the concept "Auto" means self and "troph" means feeding. An autotroph makes its own food from simple inorganic substances such as carbon dioxide and water. It does this using an energy source, which is light (photosynthesis) or chemical energy (chemosynthesis).

Examples: green plants, algae, and some bacteria.

Step 3: Evaluate each option

• A. By utilizing its stored energy: Wrong. This describes using up reserves, not obtaining food.
• B. By synthesizing simple substances using energy: Correct. The organism builds complex food (such as glucose) from simple substances (CO₂ and H₂O) using light or chemical energy. The wording is a bit loose, but this is the only option that describes making food from simple raw materials.
• C. From other organisms in exchange for some products: Wrong. This describes mutualism (symbiosis), such as nitrogen-fixing bacteria in legume root nodules.
• D. In a synthesized form, from other living organisms: Wrong. This describes heterotrophic nutrition, where food is taken in ready-made from other organisms.

Step 4: Answer The answer is B.

Exam tip: Remember "Auto = Alone". Autotrophs make their own food, and heterotrophs ("hetero" = other) get ready-made food from others. If an option mentions "ready-made" food or "other organisms," it is heterotrophic.