Question

Pigment mainly responsible for photosynthesis in red algae is
A. Phycoerythrin
B. Chlorophyll a
C. Carotene
D. Xanthophyll

Answer 1

Hint: Red algae or Rhodophyta have a pigment that gives a reddish appearance to the algae as it reflects red light. Few examples of red algae are Gelidium, Glacilaria, Porphyra, etc.

Complete answer: Red algae belong to class Rhodophyceae and is found in both marine and freshwater. The red colour of this algae is because of the presence of pigment phycoerythrin. It also has other pigments like chlorophyll and phycocyanin. They have stored food in the form of starch and polymers of galactan sulfate. Mode of nutrition is saprophytic, parasitic, or epiphytic. Cell walls are made up of cellulose and have pits in their cell wall. Reproduction is through asexual mode by the production of monospores, vegetative means, and sexual reproduction by the alternation of generation. The male sex organ is spermatangium and the female sex organ is called carpogonia.
Economic importance: It is used as food as it is rich in vitamins and minerals and antioxidants, agar-agar is obtained from red algae and is used in puddings and dairy, helps in increasing bone health and immunity. Rhodophyta is called red algae because of the presence of pigment phycoerythrin. This pigment reflects red light and absorbs blue light and gives the algae a red colour.
Hence, option A is correct answer.

Note: Rhodophyceae is the class of red algae having pigments chlorophyll a, phycoerythrin and phycocyanin. Reddish appearance is mainly because of the presence of pigment phycoerythrin. Red algae are found in both marine and freshwater habitats and store food in the form of starch and galactan sulphates. Red algae is also found at great depths because of pigment phycoerythrin as it absorbs blue light which reaches the depth of the ocean and allows red algae to carry on with photosynthesis.