Question

Which one of the following statements about photoproteins in plants is INCORRECT?

• A. Phytochromes are activated by red light
• B. Phytochromes are inactivated by far-red light
• C. Cryptochromes are sensitive to blue light
• D. Phototropins are insensitive to blue light

Answer 1

The Correct Option is D

The question is about photoproteins in plants, specifically their sensitivity to various wavelengths of light. Let's analyze each option to identify the incorrect statement: 

1. Phytochromes are activated by red light: 
   Phytochromes are a class of photoreceptor proteins in plants that are sensitive to light in the red and far-red region of the light spectrum. They are indeed activated by red light and play a crucial role in regulating various aspects of plant development such as seed germination, stem elongation, and flowering. 
   \([\text{Correct}]\)
2. Phytochromes are inactivated by far-red light: 
   After activation by red light, phytochromes can be converted back to their inactive form by exposure to far-red light. This reversible conversion is part of their action mechanism, making this statement correct. 
   \([\text{Correct}]\)
3. Cryptochromes are sensitive to blue light: 
   Cryptochromes are another class of photoreceptors that absorb blue light and are involved in regulating the circadian rhythms and growth responses of plants. This statement is correct. 
   \([\text{Correct}]\)
4. Phototropins are insensitive to blue light: 
   This statement is incorrect. Phototropins are sensitive to blue light and are involved in phototropic responses, which are movements of plants toward or away from light. Therefore, phototropins do respond to blue light, which makes this statement incorrect. 
   \([\text{Incorrect}]\)

Therefore, the incorrect statement about photoproteins in plants is: Phototropins are insensitive to blue light.