Question

Algin is a phycocolloid, obtained from the cell wall of
A) Macrocystis and Porphyridium
B) Mastigocladus and Laminaria
C) Microcystis and Nereocystis
D) Macrocystis and Fucus

Answer 1

Algin is a polysaccharide that is found in the cell walls of brown algae. Algin is a medicinal compound which finds use in the reduction of cholesterol as well as heavy metals in the body.

Complete answer:
Since we know that Algin is found only in brown seaweeds, let us look at each organism mentioned in the question and determine their type.

Macrocystis is a genus of brown algae and is known as the world’s fastest growing autotroph.
Porphyridium is a genus of red algae which is a potential source for several products like fatty acids, lipids, cell-wall polysaccharides and pigments.
Mastigocladus is a thermophilic cyanobacteria which is found in both freshwater and marine regions.
Laminaria is a genus of brown algae which are commonly called “kelp”.They are a rich source of iodine, iron and potassium. These algae are also used for the termination of pregnancy.
Microcystis is a genus of freshwater cyanobacteria which also includes the algal bloom causing organism Microcystis aeruginosa. Many species of Microcystis can produce neurotoxins and hepatotoxins.
Nereocystis is a genus of monogenic kelp (brown alga) which contains the species Nereocystis luetkeana. This algae finds use in the food and pharmaceutical industry.
Fucus is a genus of brown algae found throughout the world in the intertidal regions of rocky shores. It is an important source of alginates which finds use in the industry similar to that of agar.

Now let us look at each option one by one.
A) While Macrocystis is a brown algae, porphyridium is a red alga. Therefore, this option is incorrect.
B) While Mastigocladus is a cyanobacteria, Laminaria is a brown algae. Therefore, this option is incorrect.
C) While Microcystis is a cyanobacteria, Nereocystis is a brown algae. Therefore, this option is incorrect.
D) Both Macrocystis and Fucus are brown algae. Therefore, this is the correct option.

Thus, the correct answer is option (D) Macrocystis and Fucus.

Note: Algin (or Alginic acid) is a commonly used compound in oral and dietary supplements. It prevents the occurrence of gastroesophageal reflux by forming a gel in the presence of gastric acid which floats on top of the stomach contents.