Question

In blue-green algae, photosystem-II contains important pigment concerned with photolysis of water. It is called as
A. Beta carotene
B. Chlorophyll b
C. Cytochrome c
D. Phycocyanin

Answer 1

Hint:- The first protein complex in the light-dependent reactions of oxygenic photosynthesis is Photosystem II (water-plastoquinone oxidoreductase). It is found in plants, algae and cyanobacteria in the thylakoid membrane.

Complete solution:
A red-orange pigment found in plants and fruits, especially carrots and colourful vegetables, is beta carotene. The word beta carotene originates from "beta" in Greek and "carota" (carrot) in Latin. It is the yellow / orange pigment that brings its rich colours to vegetables and fruits.

Chlorophyll b is a green pigment in plant leaves along with Chlorophyll an LCS34-B Chlorophyll is a pigment of chlorine that is structurally similar to and formed by the same metabolic pathway as other pigments of porphyrin such as heme. A magnesium ion is at the middle of the chlorin ring.

Cytochrome c is a heme protein found between the inner and outer mitochondrial membranes in the compartment where it acts to transfer electrons between the respiratory chain's complex III and complex IV.

Phycocyanin is, along with allophycocyanin and phycoerythrin, a pigment-protein complex from the light-harvesting phycobiliprotein family. That is a chlorophyll accessory pigment. Both phycobiliproteins are water-soluble, but they do not live as carotenoids do within the membrane.

So from the above discussions we can conclude that Phycocyanin present in blue-green algae is responsible for photolysis of water. Therefore the correct answer is option (D).

Note:- Isolated from aquatic animals, phycocyanin has high quality and low toxicity properties and can be used as a practical food. Phycocyanin has been documented to have anti-oxidative, anti-inflammatory , anti-cancer, immune enhancement, liver and kidney defensive pharmacological effects. Phycocyanin is a kind of protein photosynthetic assistant that can absorb light energy effectively.