Question

Plants have many light responses, including photosynthesis, photoperiodism, and phototropism (growing toward a light source). Specific wavelengths of light absorbed by different photoreceptors trigger responses. This table shows some of the most common photoreceptors and pigments and the major regions of the spectrum in which they are active. Research shows that plants bend toward blue light. Even mutant plants that lack carotenoids will bend toward blue light. The photoreceptor is likely _____.

a) Phytochrome
b) Cryptochrome
c) Phototropin
d) Rhodopsin

Answer 1

Plants use blue-light receptors like cryptochromes and phototropins for phototropism, which is the growth towards a light source in response to blue wavelengths of light. Even in the absence of carotenoids, these photoreceptors are sufficient to enable plants to bend towards blue light. Hence, option (c) is correct.

Step-by-step explanation:

Plants exhibit various light responses, including phototropism, which is the directional growth of a plant toward a light source in response to blue light. Blue-light receptors, such as cryptochromes and phototropins, are responsible for this phototropic response.

Cryptochromes interact with and are triggered by blue light, leading to the growth and development of the plant in response to light stimuli. While mutant plants lacking carotenoids may have an impaired response, they still bend toward blue light due to the activity of these photoreceptors.

Phytochrome is a versatile photoreceptor that integrates environmental light cues to regulate plant growth and development. Rhodopsin is a light-sensitive protein found in the rod cells of the retina in the eyes of vertebrates.