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.

(N/A) $(i)$ Proteins and lipids provide structural flexibility and integrity to the plasma membrane.
$(ii)$ The plasma membrane is called selectively permeable because it regulates the entry and exit of specific substances while preventing the movement of others.
$(iii)$ Cellulose provides structural strength and rigidity to the plant cell wall. It also helps in water retention,preventing the desiccation of the cell.
$(iv)$ Plasmolysis is the phenomenon where a living plant cell loses water through osmosis,causing the cell contents to shrink away from the cell wall.
$(v)$ The flexibility of the cell membrane allows the cell to engulf food and other materials from its external environment through a process called endocytosis,which is essential for organisms like $Amoeba$.
$(vi)$ The process is known as diffusion.