The anterior. opening of our alimentary canal, the mouth, leads into the oral or buccal cavity. It contains a muscular tongue and a number of teeth of various types. Answer the following questions.
(a) How is the tongue attached to the floor of the buccal cavity?
(b) Where are taste buds present in the tongue?
(c) What do the terms
(i) diphyodont,
(ii) heterodont and
(iii) thecodont signify with reference to human dentition?
(d) Same the substance that makes up the hard chewing surface of the teeth, is made of.

(a) Identify the four types of teeth, (A, B, C, D) that are present in an adult human.
(b) Write the dental formula of an adult human.

The different regions in the human stomach are shown in the figure given above.
(a) Where is stomach located in our body?
(b) Identify the parts B, C and D in the diagram.
(c) Name the sphincters that regulate the
(i) entry and
(ii) exit of food into and out of the stomach, respectively.

Given below is the diagrammatic representation of the transverse section of human gut, showing the four basic layers (of different cell types and tissues) of its wall. Observe the diagram and answer the questions that follow:

(a) Identify and name the layer
(i) that is made of mesothelium with some connective tissue.
(ii) that forms infoldings into the lumen of alimentary canal.
(b) Identify G. Why do they have a brush-border appearance?
(c) Identify E and name the glands present in it in the duodenal region.

The above diagram shows the duct systems of liver, gall bladder and pancreas. Answer the following questions.
(a) Identify the ducts only, from among the parts labelled A to G.
(b) Where is sphincter of Oddi present?

Our food contains different nutrients like carbohydrates, fats, proteins, etc. They are digested in different regions of the alimentary canal with the help of enzymes secreted by the alimentary canal itself as well as those secreted by the associated glands.
(a) Where is starch, a carbohydrate digested in our alimentary canal? Name the glands that secrete enzymes for that,
(b) Where are fats digested in our alimentary canal? Name the group of enzymes involved in their digestion.

Absorption (with reference to nutrition) is the process by which the end products of digestion pass through the intestinal mucosa into the blood or lymph. This process may be active (using energy) or passive (without expenditure of energy).
(a) Name any three substances that are actively absorbed from the alimentary canal.
(b) Name the process by which fructose is absorbed.
(c) Name the form in which the products of fat digestion enter
(i) the intestinal mucosa
(ii) the lac teals.