Question

13. Read the following statements with
reference to the villi of small intestine.
(1) They have very thin walls.
(ii) They have a network of thin and small blood
vessels close to the surface.
(iii) They have small pores through which food
can easily pass.
They are finger-like projections
Identify those statements which enable the villi
to absorb digested food.
(a) (1). (ii) and (iv) (b)(ii), (iii) and (iv)
(c) (iii) and (iv) (d) (i) and (iv)​

Answer 1

Answer:

The following are the adaptations or those statements which enable the the villi absorb digested food:

i) They have thin walls

ii) They have a network of thin and small blood vessels close to the surface

iv) They are finger like projections

Choice A

Explanation:

The villi are finger like projections of the inner lining of the small intestine that help in the process of absorption of digested food.

Here are the adaptations that help the villi in the function of absorption of nutrients:

1) They have thin walls

The villi are one cell think which make them quite thin. This thinness helps to reduced the distance by which digested food or food nutrient is absorbed into the blood stream.

2) The villi in nature are finger-like projections

This structure of the villi increases the surface area across which digested food is absorbed from the ileum into the blood stream

3) The villi are supplied by a dense capillary network

This dense capillary network that supplies the villi, help to ensure a constant concentration gradient. The digested food once absorbed into the capillaries are transported by blood away from the villi and this is how the concentration gradient is maintained allowing more digested food to be absorbed.

Option iii is left out because the digested food does not pass through the villi via small pores, rather digested food can pass through the villi by the following processes:

1) Osmosis via a concentration gradient

2) Active transport- in which nutrients are taken through the villi by use of energy through specialized channels across the cell.

3) The process of endocytosis.

Answer 2

Answer: a)

Explanation: