Correct Option
The correct option is 1 and 3 only.
Explanation
Autotrophic nutrition is a process where an organism prepares its own food from simple inorganic materials like carbon dioxide and water, usually in the presence of sunlight and chlorophyll. This mode of nutrition is fundamental to the sustenance of life on Earth as it forms the base of the food chain.
Statement-wise Analysis
- Statement 1 is Correct: Autotrophic nutrition is characteristic of green plants, which perform photosynthesis, and certain bacteria (such as cyanobacteria and chemosynthetic bacteria). These organisms are capable of synthesizing organic compounds from inorganic raw materials.
- Statement 2 is Incorrect: The process of photosynthesis involves the absorption of light energy by chlorophyll and its conversion into chemical energy. This energy is then used to split water molecules and reduce carbon dioxide to carbohydrates. The statement incorrectly suggests the reverse conversion (chemical to light).
- Statement 3 is Correct: Heterotrophs are organisms that cannot manufacture their own food. They depend on autotrophs for their nutritional requirements, either directly (by eating plants) or indirectly (by eating animals that have eaten plants). Therefore, all heterotrophs ultimately rely on autotrophic nutrition for survival.
Key Takeaway
Autotrophic nutrition involves the synthesis of organic food from inorganic sources, primarily through photosynthesis, which converts light energy into chemical energy. It supports the survival of heterotrophs.