Question

Alginic acid is obtained from
A.Red algae
B.Green algae
C.Diatoms
D.Brown algae

Answer 1

The commercial grade of alginate is derived from Macrocystis pyrifera giant kelp, Ascophyllum nodosum, and Laminaria styles. Two bacterial genera, Pseudomonas and Azotobacter, which played a major role in unraveling its biosynthesis pathway, are also formed by alginates.

Complete answer:
The alginic acid is also known as algin or alginate. Alginate is an anionic and hydrophilic polysaccharide in nature which is found in the cell walls of Phaeophyceae i.e. brown algae. It is a linear copolymer which is made up of residues of D-mannuronic acid along with L-glucuronic acid. In case of brown algae, the cell wall is made up of cellulose as well as alginic acid. The cellulosic wall is sometimes found to be covered from outside by a gelatinous coat made up of algin.
The sodium alginate is a sodium salt of alginic acid. It is gum. Potassium alginate (KC6H7O6 ) is the potassium salt of alginic acid. Similarly, calcium alginate is made of sodium alginate which has removed the sodium ion replaced with calcium.

The manufacturing process used to extract brown seaweed sodium alginates falls into two categories: 1) the method of calcium alginate and 2) the method of alginic acid.
The process is chemically simple, but difficulties arise from the physical separations required between the viscous solution slimy residues and the separation of gelatinous precipitates holding large amounts of liquid inside the structure in order to resist filtration and centrifugation.

Hence, the correct answer is option (D)

Note: Alginic acid, also called alginic acid, is a polysaccharide that is hydrophilic and forms a viscous gum when hydrated and is widely distributed in the cell walls of brown algae. Its salts are known as alginates for metals like sodium and calcium.