The two major differences between carbon and phosphorus cycle are
A. Atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs
B. Atmospheric inputs of phosphorus through rainfall are much greater than carbon inputs
C. Gaseous exchange of phosphorus between organic and environment is not negligible
D. Gaseous exchange of phosphorus between organic and environment are negligible

Options

A. A, B
B. B, C
C. A, D
D. B ,C

Answer

To answer the question regarding the two major differences between the carbon and phosphorus cycles, we will analyze each option provided and determine which statements are correct.

### Step-by-Step Solution:

1. **Understanding the Carbon Cycle**:
- The carbon cycle involves the movement of carbon through the atmosphere, biosphere, hydrosphere, and lithosphere. Carbon is present in significant amounts in the atmosphere as carbon dioxide (CO2), which is absorbed by plants during photosynthesis.

2. **Understanding the Phosphorus Cycle**:
- The phosphorus cycle, on the other hand, does not have a significant gaseous phase. Phosphorus primarily cycles through soil, water, and living organisms. It is mainly found in rocks and minerals and is released into the environment through weathering.

3. **Analyzing Option A**:
- "Atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs."
- This statement is **correct**. The amount of phosphorus that enters the ecosystem through rainfall is indeed much smaller compared to the carbon that is continuously cycled through the atmosphere.

4. **Analyzing Option B**:
- "Atmospheric inputs of phosphorus through rainfall are much greater than carbon inputs."
- This statement is **incorrect**. As established, phosphorus inputs are much smaller than carbon inputs.

5. **Analyzing Option C**:
- "Gaseous exchange of phosphorus between organic and environment is not negligible."
- This statement is **incorrect**. Phosphorus does not have a significant gaseous phase, and therefore, the gaseous exchange of phosphorus is negligible.

6. **Analyzing Option D**:
- "Gaseous exchange of phosphorus between organic and environment is negligible."
- This statement is **correct**. Since phosphorus primarily exists in solid and dissolved forms, its gaseous exchange is indeed negligible.

7. **Conclusion**:
- The two major differences between the carbon and phosphorus cycles are:
- **A**: Atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs.
- **D**: Gaseous exchange of phosphorus between organic and environment is negligible.

Thus, the correct answer is **A and D**.