CBSE Class 10 Science 2020 · Paper 31/1/3 · Question 27(b)

(a) Diagram: the alimentary canal drawn as one continuous tube (mouth, oesophagus, stomach, small intestine, large intestine, rectum, anus) with the four parts labelled: the liver, a large gland in the upper abdomen on the right side of the body; the gall bladder, a small sac under the liver whose bile duct opens into the small intestine; the pancreas, a leaf-like gland below the stomach, in the curve of the first part of the small intestine; and the small intestine, the long coiled tube between the stomach and the large intestine (see the labelled diagram). (b) Any two of these reasons: (1) Digestion of carbohydrates, proteins and fats is completed only in the small intestine, so the food is present here as small soluble molecules that can be absorbed. (2) The inner wall of the small intestine has numerous finger-like projections called villi, which provide a large surface area for absorption. (3) The villi are richly supplied with blood vessels, which carry the absorbed food to different parts of the body. The great length of the coiled small intestine also helps, by keeping the food in contact with the absorbing surface for a long time.