Question

The pigment that absorbs red and far-red light in plant is
 A. Cytochrome.
 B. Xanthophyll.
 C. Phytochrome.
 D. Carotene.

Answer 1

Hint: Plants grow with the help of light; this light mediated development is called photomorphogenesis. Photoreceptors help in absorbing light; these mostly utilize red light and far- red light.

Complete answer:
Plants grown in dark or absence of light often have a dark and pale appearance known as etiolated growth. The growth and development in plants due to light, independent of photosynthesis, is called photomorphogenesis.
Their pigments are involved in photomorphogenesis that include phytochrome, cryptochrome and phototropin.
Phytochrome is a pigment that absorbs red light and far-red light. It also absorbs blue light. It regulates the growth and developmental process of flower induction, leaf senescence, seed germination, seed elongation etc.
Phytochrome belongs to the chromoprotein family and has a pigment known as chromophore. It is found in two reversible forms which absorb red light (666nm) Pr form and far-red light (730nm) Pfr form.
The Pr form absorbs red light which is inactive form and is converted to Pfr form. The Pfr form absorbs far-red light which is active in form. When Pfr form converts to Pr form the process is called Dark Reversion.
Cryptochrome is a blue light receptor and is made up of flavin and petrin. Phototropin also acts as a blue light receptor and has a major role in phototropism and chloroplast movement.

Hence the correct option is C. Phytochrome which absorbs red light and far-red light.

Note:
Plants grow in sunlight, Chromoprotein or phytochrome converts the Pr (red light inactive form) to Pfr (far-red light active form) which triggers the growth of the plant.