Question

In plants, opening of stomata is regulated by

• A. Red light
• B. Blue light
• C. Far-red light
• D. Ultraviolet light

Answer 1

Answer: (B)

Blue light

Stomatal opening is influenced by blue light. Though red light and blue light both have a hand in causing stomatal opening, blue light acts as a direct signal that induces the process.

This happens because in the presence of sunlight photosynthesis has to occur and the stomatal opening is an important prerequisite for it.

Red light causes opening of stomata indirectly as it increases photosynthesis which in turn requires more carbon dioxide so the pores have to open.

Far-red light and UV light cannot influence stomatal opening.

So the correct answer is 'Blue light'.