What are the necessary conditions for autotrophic nutrition and what are its by- products?

Explanation

### Step-by-Step Solution

1. **Definition of Autotrophic Nutrition**:
- Autotrophic nutrition is a mode of nutrition in which organisms, primarily green plants, synthesize their own food from simple substances.

2. **Necessary Conditions for Autotrophic Nutrition**:
- **Carbon Dioxide (CO₂)**: This gas is absorbed from the atmosphere through the stomata in the leaves.
- **Water (H₂O)**: Water is taken up by the roots from the soil.
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