The correct option is (c) 2 and 3 only.
Explanation
Nutrition is the process by which living organisms obtain and utilize nutrients for energy, growth, and maintenance. Based on the source of food, the mode of nutrition is primarily classified into two types: Autotrophic and Heterotrophic.
Statement-wise Analysis
- Statement 1 is Incorrect. Autotrophic nutrition is the mode wherein organisms synthesize their own organic food from simple inorganic substances like carbon dioxide and water, usually in the presence of sunlight (e.g., green plants). The mode where organisms take in food prepared by others is called heterotrophic nutrition.
- Statement 2 is Correct. Animals cannot synthesize their own food because they lack chlorophyll and the necessary metabolic pathways for photosynthesis. Therefore, they depend on plants or other animals for their nutritional requirements and are classified as heterotrophs.
- Statement 3 is Correct. The term ‘heterotroph’ is derived from the Greek words heteros (meaning 'other') and trophos (meaning 'nourishment'). It refers to organisms that depend on other organisms (producers or other consumers) for their food and energy needs.
Key Takeaway: The fundamental distinction in nutrition lies between Autotrophs (producers who synthesize food) and Heterotrophs (consumers who ingest or absorb food prepared by others).