Of the total incident solar radiation the proportion of PAR is:
(a) More than `80%`
(b) About `70%`
(c) About `60%`
(d) Less than `50%`

Options

A. More than `80%`
B. About `70%`
C. About `60%`
D. Less than `50%`

Answer

To solve the question regarding the proportion of Photosynthetically Active Radiation (PAR) from the total incident solar radiation, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of PAR**:
- PAR stands for Photosynthetically Active Radiation. It refers to the portion of the light spectrum that plants use for photosynthesis, primarily in the wavelengths of 400 to 700 nanometers.

2. **Identify the Source of Energy**:
- The primary source of energy for ecosystems is solar energy. This energy is critical for processes like photosynthesis in plants.

3. **Determine the Proportion of PAR**:
- It is known that approximately 50% of the total incident solar radiation that reaches the Earth is classified as PAR. This means that out of all the solar energy, about half is usable by plants for photosynthesis.

4. **Analyze the Options**:
- Given the options:
- (a) More than 80%
- (b) About 70%
- (c) About 60%
- (d) Less than 50%
- Since we established that PAR is around 50%, the correct answer must be less than or equal to 50%.

5. **Choose the Correct Answer**:
- Based on the analysis, the correct answer is (d) Less than 50%.

### Final Answer:
The proportion of PAR from the total incident solar radiation is (d) Less than 50%.

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