Question

Answer briefly:

(a) Why are villi present in the intestine and not in the stomach?

(b)How does pepsinogen change into its active form?

(c) What are the basic layers of the wall of alimentary canal?

(d) How does bile help in the digestion of fats?

Answer 1

Answer:

a. villi are used for the absotption of food and complete absorption of food takes place in small intestine not in stomach.

b. inactive pepsinogen is secreted by stomach when hydrochloric acid are released in stomach makes acidic environment and thus in presrmce of acidic medium inactive pepsinogen gets activated.

c. there are three layers of wall of alimentary cannal. These are:

endoderm

medoderm and ectoderm

d. bile have enzymes that digest fat .

Answer 2

(a) The mucosal wall of the small intestine forms millions of tiny finger-like projections known as villi. These villi increase the surface area for more absorption of nutrients.
(b) The gastric gland secretes gastric juice which contains pepsinogen, HCl, and mucus. HCl mixed with food and make it acidic when pepsinogen comes in contact with acidic food it gets activated and converts into the pepsin an active enzyme.
(c) The wall of the alimentary canal is made up of four layers serosa, muscularis, submucosa and mucosa.
(d) Bile is secreted by the liver it emulsifies the fats and activates the lipase enzyme for further digestion of fat.