CBSE Class 10 Answered
Gastric vacuole is nothing but food vacuole. But the term gastric vacuole, instead of food vacuole, is used mainly in case of protozoans. A gastric vacuole is formed in the following manner: After entering the mouth of protozoans, the water and food are collected in a vacuole which, upon reaching a certain size, is carried away from the region of the mouth by protoplasmic movement. Such vacuoles are known as gastric vacuoles or im-
provised stomachs, for while in them food substances are digested by means of digestive ferments that appear in the vacuole. Bacteria taken in as food are killed by an acid secreted in the gastric vacuole. The acid reaction persists for a short time, after which the fluid of the vacuole gives an alkaline reaction. Disintegration of the bacteria occurs in the alkaline medium which then gets distributed throughout the protoplasm. The acid and alkaline reactions of fluids in gastric vacuoles vary widely in different types of protozoa.