Question

Pigment acting as a reaction center during photosynthesis is
(a) Carotene
(b) Phytochrome
(c) Chlorophyll a of ${ P }_{ 700 }$
(d) Cytochrome

Answer 1

Hint: It is associated with photosystem I in plants, algae, and cyanobacteria. Its name is derived from the word “pigment”, and the maximal wavelength of light it can absorb, at which the phenomenon of photobleaching would occur. The structure consists of a heterodimer with two distinct molecules.

Complete answer:
The process by which green plants and certain other organisms transform light energy into chemical energy is called photosynthesis. In green plants, light energy is captured and used to convert water, carbon dioxide, and minerals into oxygen and energy- rich organic compounds during photosynthesis.
Again the structural and functional units of protein complexes in the process of photosynthesis are known as the photosystems which together carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons. The two kinds of photosystems are PS II and PS I. These two photosystems I and II contain many pigments that help collect light energy, as well as a special pair of chlorophyll molecules found at the core (reaction center) of the photosystem. The special pair of photosystems I am called ${ P }_{ 700 }$, while the special pair of photosystem II is called ${ P }_{ 680 }$.
A protein that is the site of the light reactions of photosynthesis is known as the photosynthetic reaction center. The reaction center contains pigments such as chlorophyll and pheophytin. The reaction centers absorb light, promoting an electron to a higher energy level within the pigment.
Additional Information:
1) For the development and maintenance of life on earth, oxygenic photosynthesis is indispensable. By converting light energy into chemical energy and by producing molecular oxygen and consuming carbon dioxide these processes maintain the balance.
2) The terminal electron acceptors in PS I are ferredoxin- like iron- sulfur cluster proteins. And in the type II photosystems ultimately shuttle electrons to a quinone terminal electron acceptor.
3) Oxygenic photosynthesis can be performed by plants and cyanobacteria; cyanobacteria are believed to be the progenitors of the photosystem- containing chloroplasts of eukaryotes.
4) Photosystems are found in the thylakoid membranes of plants, algae, and cyanobacteria. They are located in the chloroplasts of plants and algae, and the cytoplasmic membrane of photosynthetic bacteria.
So, the correct answer is, ’(c) Chlorophyll an of ${ P }_{ 700 }$ .’

Note: Photosynthesis is probably one of the most multidisciplinary fields of research. The synergy of many approaches, such as genetics, genomics, molecular biology, biochemistry, biophysics, spectroscopy, proteomics, and physiology has been of crucial importance in elucidating the properties of both photosystems as well as their physiological role at the organelle and whole organism level. The continuous development of such multidisciplinary approaches will be necessary to improve the understanding of the functionality and to shed light on the yet unknown characteristic of these extremely efficient natural energy converters.