Effectiveness of different wavelength of light on photosynthesis is measured by

Options

A. Quantum yield
B. Quantum requirement
C. Absorption spectrum
D. Fluorescence

Answer

To solve the question regarding the effectiveness of different wavelengths of light on photosynthesis, we will analyze the options provided and determine which one is correct based on the principles of photosynthesis and the role of light.

### Step-by-Step Solution:

1. **Understanding Photosynthesis**: Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigments. The light energy is absorbed by these pigments, which then convert it into chemical energy.

2. **Identifying the Role of Light Wavelengths**: Different wavelengths of light have varying effects on the rate of photosynthesis. Chlorophyll primarily absorbs light in the blue (around 450-475 nm) and red (around 650-675 nm) regions of the spectrum.

3. **Evaluating the Options**:
- **Quantum Yield**: This refers to the efficiency of photon emission and is defined as the ratio of the number of photons emitted to the number of photons absorbed. It does not specifically measure the effectiveness of different wavelengths on photosynthesis.
- **Quantum Requirement**: This is the inverse of quantum yield and indicates the number of quanta of light energy required to produce one molecule of oxygen. While it relates to light energy, it does not directly measure the effectiveness of different wavelengths.
- **Absorption Spectrum**: This represents the range of wavelengths that a pigment can absorb. The absorption spectrum of chlorophyll shows peaks at specific wavelengths (blue and red), indicating which wavelengths are most effective for photosynthesis.
- **Fluorescence**: This is the emission of light by a substance that has absorbed light. It is not a measure of the effectiveness of light wavelengths in photosynthesis.

4. **Conclusion**: Based on the analysis, the effectiveness of different wavelengths of light on photosynthesis is best measured by the **absorption spectrum** of chlorophyll. Therefore, the correct answer is **option C: Absorption Spectrum**.