We eat food composed of all the nutrients like carbohydrates,proteins,fats,vitamins,minerals,and water. After digestion,these are absorbed in the form of glucose,amino acids,fatty acids,glycerol,etc. What mechanisms are involved in the absorption of digested food and water?

The proteins and lipids,essential for building the cell membrane,are manufactured by

Plasmolysis in a plant cell is defined as

$(a)$ Name the organelle which provides turgidity and rigidity to the plant cell. Name any two substances which are present in it.
$(b)$ How are they useful in unicellular organisms?

Classify the organisms on the basis of the number of cells. Give two examples each.

Give short answers:
$(i)$ What is the role of proteins and lipids in the plasma membrane?
$(ii)$ Why is the plasma membrane called selectively permeable?
$(iii)$ What is the role of cellulose in the cell wall?
$(iv)$ What is meant by plasmolysis?
$(v)$ What is the advantage of the flexibility of the cell membrane?
$(vi)$ Name the process which is useful for the movement of substances like $CO_{2}$ and $O_{2}$ across the cell membrane.