Question

Which of the following wavelength of light is absorbed maximum for photosynthesis?

• A. Red light
• B. Blue light
• C. Green light
• D. Yellow light

Answer 1

The correct option is B Blue light

Blue light is the wavelength of light is absorbed maximum for photosynthesis. Blue light is absorbed not only by chlorophyll, but also by carotenoids, and some carotenoids are not in the chloroplasts. Further, carotenes and xanthophylls make up the carotenoids. Carotenes do not transfer absorbed energy efficiently to chlorophyll and thus some part of absorbed blue light is not going to photosynthesis. On the other hand, all of red light is absorbed by chlorophylls and used effectively.

All plants, however, has chlorophyll a, which absorbs most strongly at ~450 nm, or a bright blue color. This wavelength is strong in natural sunlight and somewhat present in incandescent lights, but is very weak in traditional fluorescent lights.

So, the correct answer is option B.