Question

Which of the following is non- photosynthetic photoreceptor pigment?
A. Phytochrome
B. Xanthophyll
C. Chlorophyll
D. Cytochrome

Answer 1

Hint: Non- photosynthetic photoreceptor pigments are those pigments that do not play a role in the photosynthesis but have other functions to do. They mostly perform functions such as growth and development.

Complete answer: Pigments are the substances that have the ability to absorb light at a specific wavelength. We all are familiar with the wavelength of the visible spectrum of light or of VIBGYOR. We can see that the wavelength at which maximum absorption by chlorophylls a, i.e., in the blue and the red region, also shows a high rate of photosynthesis. We can say chlorophyll a is the chief pigment in the process of photosynthesis.
This pigment helps in the trapping of the light, other thylakoid pigments like chlorophyll b, xanthophylls and carotenoids which are also termed as the accessory pigment and also helps in the absorption of light and transfer the energy to chlorophyll a. They not just help in enabling a wider range of wavelength of incoming light to be utilised for the process of photosynthesis but also protects the chlorophyll a from photo- oxidation.
When chlorophyll absorbs a wavelength of 680 nm it becomes excited and jumps in the orbital. These electrons are picked up by electron acceptor which passes them to an electrons transport system consisting of cytochromes. Cytochromes plays a major role in the electron transport system.
Xanthophylls and carotenoid play a major role in the cyclic and non- cyclic photo - phosphorylation also. Phytochromes is a photoreceptor in plants, bacteria that is used to detect the light . They are involved in photoperiodism in many of the flowering plants and also helps in the regulation of the time of flowering based on the length of day and night. It also does not take part in the photosynthesis process.

So, the correct answer is option A, Phytochromes.

Note: A large pool of secondary metabolites, belonging mainly to a highly diversified array of flavonoids and to the closely related anthocyanins as well as betacyanins are termed as non - photosynthetic pigments. Phytochrome is a non - photosynthetic pigment that does not take part in photosynthesis and is mainly responsible for seed dormancy, shoot elongation, seed germination etc.