Modes of nutrition: An organism that depends exclusively on pre-synthesized food molecules (ready-made organic carbon) is termed what?

Introduction / Context:
Classifying organisms by nutrition clarifies how they obtain energy and carbon. This question targets the definition of heterotrophy versus autotrophy.

Given Data / Assumptions:

• The organism relies on pre-formed organic molecules for both energy and carbon.
• No photosynthesis or CO2 fixation is implied.
• The term sought is a standard textbook definition.

Concept / Approach:
Heterotrophs use organic compounds produced by other organisms. Autotrophs fix CO2 using light (photoautotrophs) or chemical energy (chemoautotrophs). The stem explicitly describes exclusive dependence on pre-synthesized food, which is heterotrophy.

Step-by-Step Solution:

Verification / Alternative check:
Animal nutrition and many microbes exemplify heterotrophy—requiring complex organics for growth.

Why Other Options Are Wrong:

Common Pitfalls:
Equating “non-photosynthetic” with heterotrophy; some non-photosynthetic organisms are still autotrophs (chemoautotrophs).

Final Answer:
Heterotrophic.