Name the nucleic acids present in the cell.

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.

State the reason for the following:
$(i)$ Mitochondria are known as the powerhouse of the cell.
$(ii)$ Plastids are able to make their own protein.
$(iii)$ Plant cells shrink when kept in a hypertonic solution.

When do chromatin fibres organize themselves into chromosomes?

What is the significance of the Golgi apparatus?

Draw a neat labelled diagram of an animal cell.