— colors of visible light will increase the rate of photosynthesis.
A red and blue
B black and violet
C pink and Yellow
D orange and green
The correct answer and explanation is:
Correct Answer: A. Red and blue
Explanation:
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize food (mainly glucose) from carbon dioxide and water. This process occurs primarily in the chloroplasts of plant cells and relies heavily on light energy absorbed by chlorophyll, the green pigment found in plants.
Role of Light Colors in Photosynthesis:
Visible light is made up of various colors, each with a different wavelength. The effectiveness of each color in driving photosynthesis varies depending on how well chlorophyll pigments absorb that color. Chlorophyll primarily absorbs blue (around 430–450 nm) and red light (around 640–680 nm) very efficiently, while it reflects green light, which is why plants appear green.
- Blue light is high in energy and helps stimulate the opening of stomata, promote leaf growth, and drive photosynthesis efficiently.
- Red light has the ideal wavelength for chlorophyll to absorb and is very effective in promoting photosynthetic activity, especially in the later stages like flowering and fruiting.
Why the Other Options Are Incorrect:
- B. Black and violet: Black is not a color but an absence of light—it contributes nothing to photosynthesis. Violet light has high energy but is less efficiently used than blue or red.
- C. Pink and yellow: Pink is not a true spectral color, and yellow light is poorly absorbed by chlorophyll.
- D. Orange and green: Orange is moderately absorbed but not as efficiently as red or blue. Green is mostly reflected, not absorbed.
Conclusion:
To increase the rate of photosynthesis, red and blue light are the most effective because they are the wavelengths best absorbed by chlorophyll, thus driving the light-dependent reactions efficiently.