In which of the following groups of organisms the food material is broken down outside the body and then absorbed?

The first enzyme to mix with food in the digestive tract is :

Which of the following is the correct statement ?

Which of the following is the correct sequence of parts as they occur in the human alimentary canal ?

When a person eats sugary food, then organisms A present in his mouth act on sugar to produce a substance B. The substance B first dissolves the calcium salts from the top part C of the tooth and then from its middle part D forming holes E. These holes ultimately reach the part F in the lower part of tooth which contains nerves and blood vessels. The substance B irritates the nerve endings inside the tooth causing toothache.

(a) What are (i) organisms A, and (ii) substance B?

(b) What are (i) part C, and (ii) part D, of tooth known as?

(c) By what name are the holes E in the tooth known?

(d) Name the part F of the tooth.

(e) What will happen if organisms A reach part F of the tooth ?