Formative Practice 9.2 (Form 4 Biology Textbook Exercise and Answer)

Question 1:
Name the main structures for the absorption of digested food.

The main structure in food absorption is villi.

Question 2:
Name the structure in the villus involved in the transporting of the following nutrients:
(a) amino acids
(b) vitamins A and E

(a) Blood capillaries

(b) Lacteal

Question 3:
Explain the adaptations of the small intestine to increase the surface area for absorption of nutrients.

Long small intestine. The inner layer of the small intestine is highly folded and covered with villi to increase surface area for nutrient absorption. There are many microvilli found on the epithelial surface of the villi.

Question 4:
Explain how the following substances can be transported across the plasma membrane.
(a) Glucose, galactose and amino acids
(b) Fatty acids and glycerol

Glucose, galactose and amino acids are actively transported across the epithelial cell to the blood vessels by carrier proteins against the concentration gradient. Fatty acids and glycerols diffuse across the plasma membrane into the lacteal through simple diffusion.

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