70. Cryptochromes control photomorphogenesis in response to:
Options:-
A. Red light
B. Far-red light
C. Infra-red light
D. Blue and UV-A light

Introduction:

Cryptochromes are light-sensitive proteins found in plants and animals that play a crucial role in regulating growth and development in response to light. Specifically in plants, cryptochromes are key players in photomorphogenesis, the process by which plants change their growth patterns based on light cues. This article will delve into how cryptochromes respond to light and the significance of their role in photomorphogenesis.

Explanation of the Answer:

The correct answer is D. Blue and UV-A light. Here’s why:

1. A. Red light:

   • While red light plays a role in plant growth and development through photoreceptors like phytochromes, cryptochromes are not primarily involved in the response to red light. Phytochromes are the primary receptors that mediate responses to red and far-red light.

2. B. Far-red light:

   • Like red light, far-red light is mainly detected by phytochromes rather than cryptochromes. Cryptochromes do not respond to far-red light; their role is more focused on blue and UV-A light.

3. C. Infra-red light:

   • Cryptochromes do not respond to infra-red light. Infra-red light is typically absorbed by other types of photoreceptors and is not involved in the photomorphogenic processes that cryptochromes influence.

4. D. Blue and UV-A light:

   • Correct. Cryptochromes are most responsive to blue and UV-A light. These light wavelengths trigger cryptochromes to mediate various aspects of photomorphogenesis, such as seedling development, leaf expansion, and phototropism. Cryptochromes play a crucial role in regulating these processes by initiating signal transduction pathways that affect gene expression and cell growth.

Conclusion:

Cryptochromes are light receptors that control photomorphogenesis in plants, specifically responding to blue and UV-A light. They are essential in regulating growth and development processes in response to these light wavelengths, ensuring plants adapt to their environment effectively.

The correct answer is: D. Blue and UV-A light.