Which is the first enzyme to mix with food in the digestive tract?

Name the following with reference to the alimentary canal:
$(a)$ $(i)$ The largest gland.
$(ii)$ The gland that secretes digestive enzymes as well as hormones.
$(iii)$ The part where digested food is absorbed.
$(b)$ What are villi? Mention their function.

What are the functions of gastric glands present in the wall of the stomach?

What is the role of the acid in our stomach?

Select the correct statement.

Draw the diagram of the alimentary canal of a human and label the following parts:
Mouth,Oesophagus,Stomach,Intestine.