Which of the following graphs correctly depicts the rate of photosynthesis of sun plant (P) and shade plant (Q)?

Options

A.
B.
C.
D.

Explanation

To determine which graph correctly depicts the rate of photosynthesis for sun plants (P) and shade plants (Q), we need to understand how these two types of plants respond to varying light intensities.

### Step-by-Step Solution:

1. **Understanding Sun Plants and Shade Plants**:
- Sun plants (P) are adapted to high light intensities and can achieve high rates of photosynthesis when exposed to strong sunlight.
- Shade plants (Q), on the other hand, thrive in low light conditions and are more efficient at lower light intensities. They cannot achieve high photosynthetic rates under intense light.

2. **Graph Characteristics**:
- The x-axis of the graph typically represents light intensity (photon flux density), while the y-axis represents the rate of photosynthesis (carbon dioxide uptake).
- For sun plants, the graph should show a steep increase in the rate of photosynthesis with increasing light intensity, eventually reaching a plateau as it saturates.
- For shade plants, the graph should show a more gradual increase in the rate of photosynthesis with light intensity, and it will not reach the same high rates as sun plants, even at high light intensities.

3. **Analyzing the Given Graphs**:
- **Graph A**: Shows both plants rising rapidly and reaching high rates at high light intensity, which is incorrect for shade plants.
- **Graph B**: Shows a plateau for sun plants at low light intensity, which is also incorrect because sun plants should rise steeply at high light intensity.
- **Graph C**: Similar issues as Graph A, with both plants showing high rates at high light intensity.
- **Graph D**: Shows sun plants rising steeply with increasing light intensity and shade plants rising more gradually, which is consistent with their respective adaptations.

4. **Conclusion**:
- Based on the analysis, **Graph D** correctly depicts the rate of photosynthesis for sun plants (P) and shade plants (Q). Sun plants show a steep increase in photosynthesis with light intensity, while shade plants show a slower increase.

### Final Answer:
The correct graph is **D**.