CBSE Class 10 Science 2020 · Paper 31/C/1 · Question 19

Absorption: the inner lining of the small intestine has numerous finger-like projections called villi, which greatly increase the surface area for absorption. The villi have thin walls and are richly supplied with blood vessels. Digested food (glucose, amino acids, fatty acids and glycerol) passes through these walls into the blood, with fatty acids and glycerol going mainly into the lymph vessels (lacteals), and the blood carries it to each and every cell of the body. Why necessary: food is useful only when it reaches the cells, where it is used to obtain energy, to build new tissues and to repair old ones. Food that is not absorbed cannot be used and is passed out of the body.