The part of P and Q are present only in plant cells, and they are not present in animal cells. The part P contains a green pigment called R whereas part Q is made of a tough material S. The part P takes part in the food making process whereas part Q gives shape and support to the plant cell.

(a) What is (i) P, and (ii) Q?

(b) What is (i) R, and (ii) S?

(a) (i) The part P is Chloroplasts

Chloroplasts are the food producers in plant cells and they are not present in animal cells because animal cells do not make their own food. 

(ii) The part Q is Cell wall

The cell wall is absent in the animal cells because they don't need cell walls. The main purpose of a cell wall is to provide stability and stiffness to the cell. And it is made up of cellulose. 

(b) (i) The part R is Chlorophyll

Chlorophyll is the green pigment present in the leaves. 

(ii) The part S is Cellulose

Cellulose is a fiber and wood, cotton, etc. all contain cellulose.