CBSE Class 10 Science 2019 · Paper 31/4/1 · Question 12

(a)(i) Saliva: its enzyme salivary amylase breaks down starch into sugar (maltose); saliva also wets the food so that it can be swallowed easily. (a)(ii) $\text{HCl}$ in the stomach: it makes the medium acidic, which helps the enzyme pepsin act, and it kills germs that enter with the food. (a)(iii) Bile juice: it emulsifies fats, breaking large fat globules into smaller ones so that lipase can act on them, and it makes the acidic food from the stomach alkaline for the pancreatic enzymes. (a)(iv) Villi: they increase the surface area for the absorption of digested food; their blood vessels carry the absorbed food to all the cells of the body. (b)(i) Pepsin: it digests proteins (into smaller peptides) in the stomach. (b)(ii) Lipase: it digests fats, breaking emulsified fats into fatty acids and glycerol.