Percentage of Light Energy Utilized for Photosynthesis by Higher Plants

Higher plants, also known as vascular plants, have the ability to undergo photosynthesis, a process where they convert light energy into chemical energy in the form of glucose. However, not all of the light energy that plants receive is utilized for photosynthesis. The percentage of light energy utilized for photosynthesis can vary depending on various factors.

Factors Affecting Light Energy Utilization for Photosynthesis
1. Light Intensity: The intensity of light plays a crucial role in the rate of photosynthesis. In general, higher light intensity leads to higher rates of photosynthesis. However, there is an optimal light intensity beyond which the rate of photosynthesis does not increase further.

2. Light Quality: Plants primarily utilize light in the blue and red regions of the electromagnetic spectrum for photosynthesis. Different pigments in the chloroplasts, such as chlorophyll a and chlorophyll b, absorb light at specific wavelengths. Light energy in the green region is not efficiently absorbed by these pigments and is thus not utilized for photosynthesis.

3. Temperature: Photosynthesis is also influenced by temperature. Higher temperatures can enhance the rate of photosynthesis up to a certain point, beyond which it can become detrimental to the plant.

4. Carbon Dioxide Availability: Carbon dioxide (CO2) is an essential raw material for photosynthesis. Higher concentrations of CO2 can increase the rate of photosynthesis, up to a certain threshold.

Percentage of Light Energy Utilized for Photosynthesis
The correct answer to the given question is option 'D' - 1-2%. This means that only a small percentage of the total light energy received by plants is actually utilized for photosynthesis. The remaining light energy is either reflected, transmitted, or absorbed for other purposes.

Reasons for Low Percentage of Light Energy Utilization
1. Inefficiencies in Chlorophyll Absorption: Not all wavelengths of light are efficiently absorbed by chlorophyll pigments. Green light, for example, is reflected and not utilized for photosynthesis. This inefficiency contributes to the low percentage.

2. Losses due to Reflection and Transmittance: Some light energy is reflected off the surface of leaves, reducing the overall amount available for photosynthesis. Additionally, some light energy is transmitted through the leaves, passing through without being absorbed.

3. Other Metabolic Processes: Plants utilize a portion of the light energy for other metabolic processes such as respiration, growth, and reproduction. These processes also require energy and reduce the overall percentage of light energy available for photosynthesis.

4. Environmental Factors: Environmental factors such as suboptimal light intensity, temperature, and CO2 availability can further decrease the percentage of light energy utilized for photosynthesis.

Overall, the percentage of light energy utilized for photosynthesis by higher plants is relatively low, ranging from 1-2%. This highlights the importance of optimizing environmental conditions and maximizing the efficiency of light absorption to ensure optimal plant growth and productivity.