Question

Agar-Agar is obtained from-
A. Gigartina
B. Gelidium
C. Gracilaria
D. All of the above

Answer 1

Hint:- The unbranched polysaccharide collected from the cell walls of certain species of red algae is a jelly-like material. It has been used in desserts across Asia as an ingredient, and also as a solid substrate for microbiological work to contain culture media.

Complete step-by-step solution:-
Option A is incorrect. The word 'agar' derives from agar-agar, the Malay term for the red algae from which the jelly is made (Gigartina, Gracilaria). Gigartina is able to bind to healthy membranes of cells and helps with viral infections. Gigartina is useful for viral infection suppression. Controlling certain autoimmune disorders has also been effective.
Option B is incorrect. Gelidium is a species of red thalloid algae, irregularly branched or present on either side of the main stem in rows. Gelidium develops tetraspores. To make agar, many of the algae in this genus are included.
Option C is incorrect. Gracilaria is significant for its economically important as an agarophyte and for its use as a foodstuff for humans and for different species of shellfish and is a genus of red algae. They are very flexible, but they are usually used in three ways. Washed and eaten as a raw or boiled salad, as a thickener or sun-bleached, dried and later used as a gelatin based on vegetables.
Option D is correct. Agar -Agar is used specifically to consolidate the media. It is collected from algae. It is an agarose polysaccharide. It is primarily obtained by boiling the algae suspension. It forms the supporting structure of some types of algae in the cell walls. It is a linear polymer consisting of repeating agarobiose units, a disaccharide composed of 3,6-anhydro-L-galactopyranose and D-galactose. Agar-Agar can be found in Gigartina, Gelidium, Gracilaria.
So, the correct answer is Option D.

Note:- As a clarifier for fermentation, paper and cloth sizing, Agar may also be used as a laxative, appetite suppressant, gelatin vegetarian replacement, soup thickener, fruit preserves, ice cream and other desserts.