Distinguish between saliva and bile on the basis of source of secretion.

Distinguish between milk teeth and permanent teeth on the basis of number.

Distinguish between lactase and lipase on the basis of substrate on which they act.

Draw a neat diagram of the "vertical section of a grinding tooth" and label all its important parts. Answer the following questions :

(i) Name the substance which covers the visible portion of the tooth.

(ii) Which of the above labelled parts of the tooth is hard like a bone ?

(iii) Name the substance which covers the embedded part of the tooth.

(iv) What are caries ?

(v) Define plaque.