<div><b>When a person puts food in his mouth, then teeth cut it into small pieces, chew and grind it. The glands A in the mouth secrete a substance B which is mixed with the food by tongue. The substance B contains an enzyme C which starts the digestion of food in the mouth. The slightly digested food from the mouth goes down a tube D. The special type of movements E in the walls of tube D push the food into stomach for further digestion. The stomach wall secretes gastric juice containing three substance F, G and H. One of the functions of F is to kill bacteria which may enter the stomach with food. The substance G protects the inside layer of stomach from the damaging effect of substance F whereas substance H is an enzyme for digestion. The partially digested food then enters into small intestine for further digestion.</b><b>(a)</b> What is (i) gland A (ii) substance B, and (iii) enzyme C?<b>(b)</b> Name the tube D.<b>(c) </b>What is the movement E known as?<b>(d) </b>What are (i) F (ii) G, and (iii) H?</div>