Question

Mannitol is the stored food in-
A) Gracilaria
B) Chara
C) Porphyra
D) Fucus

Answer 1

Mannitol is a naturally occurring sugar alcohol that is found in fruits and vegetables. It is used as a diuretic for people with kidney disorders. It is also used in the formulation of medicine, as a stored food and also in analytical chemistry techniques.

Complete answer:
Plants can synthesize their own food by the process of photosynthesis. The excess food produced that is not required at the moment is stored in stems and other parts of the plant. Stored food helps the plant to grow and survive during harsh environmental conditions when manufacturing of food is not possible. Plants also store their extra food in seeds so that when the seed grows it can utilise that food. Gracilaria is a red algae belonging to Rhodophyceae. It’s stored food in the form of floridean starch and galactan $SO_4$polymers. Chara is a green algae belonging to Chlorophyceae. It stores food in the form of starch and oil. Porphyra is a seaweed that grows in cold and shallow seawater and belongs to Rhodophyceae. The stored food in their case is also floridean starch and galactan polymer. Finally Fucus is a brown algae belonging to Phaeophyceae. They store food in the form of laminarin, mannitol and oil.

Hence the correct answer is option (D) Fucus.

Note: Algae are important organisms that have major economic importance since they serve as food, fodder, in fish farming, as a fertilizer and biological indicators. Knowledge about the stored food helps us to determine the economically important substances that can be formed from them.