**Explanation:**

**Adaptations in Plants for Low Light Intensity:**

Plants growing in low light conditions have to adapt to the limited availability of light energy for photosynthesis. They have developed several adaptations to maximize their ability to capture and utilize light efficiently. One such adaptation is the larger photosynthetic unit size compared to plants growing in high light intensity.

**Larger Photosynthetic Unit Size:**

The photosynthetic unit size refers to the number of chlorophyll molecules present in the light-harvesting complexes of the chloroplasts. In plants adapted to low light intensity, the photosynthetic unit size is larger than in plants adapted to high light intensity. This means that there are more chlorophyll molecules present in the light-harvesting complexes of the chloroplasts in low light adapted plants.

**Reasoning:**

The larger photosynthetic unit size allows plants to absorb and utilize more light energy under low light conditions. This adaptation helps plants to maximize their photosynthetic efficiency and compensate for the limited availability of light energy. By having a larger photosynthetic unit size, plants can capture more photons and convert them into chemical energy through photosynthesis.

**Advantages of Larger Photosynthetic Unit Size:**

1. Increased Light Absorption: The larger photosynthetic unit size allows plants to capture more photons from the available light, enhancing their light absorption capacity.

2. Enhanced Photosynthetic Efficiency: The increased number of chlorophyll molecules in the light-harvesting complexes increases the efficiency of light energy utilization for photosynthesis.

3. Improved Carbon Fixation: The larger photosynthetic unit size enables plants to fix more carbon dioxide (CO2) through the Calvin cycle, leading to increased rates of CO2 fixation and subsequent sugar production.

**Conclusion:**

Plants adapted to low light intensity have developed several adaptations to maximize their ability to capture and utilize light energy efficiently. One such adaptation is the larger photosynthetic unit size, which allows these plants to absorb and utilize more light energy under low light conditions. This adaptation helps them to enhance their photosynthetic efficiency and maintain their growth and survival in environments with limited light availability.