Correct Option
The correct option is (c) 2 and 3 only.
Explanation
Nutrition is the process by which organisms obtain and utilize food for energy, growth, and repair. Based on the mode of nutrition, organisms are broadly classified into two categories: Autotrophs (producers) and Heterotrophs (consumers).
Statement-wise Analysis
- Statement 1 is Incorrect: Autotrophs are organisms capable of synthesizing their own food from inorganic substances like carbon dioxide and water, typically using sunlight (photosynthesis). Humans lack chlorophyll and the metabolic machinery required for photosynthesis; therefore, they are not autotrophs.
- Statement 2 is Correct: Humans obtain nutrients and energy by consuming organic matter. This intake comes directly from plants or indirectly by consuming animals that have eaten plants.
- Statement 3 is Correct: Organisms that cannot manufacture their own food and depend on external sources are classified as heterotrophs. Humans exhibit holozoic nutrition, a type of heterotrophic nutrition involving the ingestion of solid food.
Key Takeaway: Humans are heterotrophs with a holozoic mode of nutrition, meaning they rely on complex organic substances derived from plants or other animals for survival, unlike autotrophs (green plants) which synthesize their own food.