Question

“Carrageenan” is obtained from
(a) Chondrus crispus
 (b) Laminaria
(c) Gelidium
(d) Macrocystis

Answer 1

Hint: It is also known as Irish moss and is abundantly found in Ireland. The thallus of this algae is finely and profusely branched.

Complete answer:
Carrageenan is a polysaccharide obtained from the cell wall of Chondrus crispus (Irish moss). It is used in the stabilization of emulsions in paints and cosmetics and in the alcohol and sugar industry.
Chondrus crispus is a red alga which is usually found near the seashores of the Northern Atlantic.

Additional Information: Algae can be divided into three subdivisions based on their colour or pigments
- Rhodophyceae(Red algae): The members of Rhodophyceae are commonly called red algae because of the predominance of the red pigment, phycoerythrin. The cell wall of red algae is known for the presence of certain mucopolysaccharides like agar, carrageenan. Gelidium is an example of red algae. It is a major source of agar, a solidifying agent used in bacterial cultures.
-Phaeophyceae(Brown algae): Phaeophyceae are brown coloured due to the presence of fucoxanthin. E.g. Laminaria which is widespread kelp, popularly known as devil’s apron. Macrocystis is the largest kelp. Kelps are giant brown algae.
 -Chlorophyceae(Green algae): Chlorophyceae has an abundance of chlorophyll a and b, imparting green colour.Their reserve food is starch which is a polysaccharide composed of amylose and amylopectin. E.g. Spirogyra
So, the correct answer is 'Chondrus crispus'

Note: Mucopolysaccharide is a long chain of polymers with repeating units of amino acid linked with a monosaccharide. They have a unique capacity to bind and hold water, thus forming a gel when mixed with water. Irish moss also contains anti-viral properties. It has been used in Ireland, as a traditional remedy to cure respiratory problems.