Differentiate between: Nucleus and nucleoid.

$(a)$ What are the consequences of the following conditions?
$(i)$ $A$ cell having higher water concentration than the surrounding medium.
$(ii)$ $A$ cell having lower water concentration than the surrounding medium.
$(iii)$ $A$ cell having equal water concentration to its surrounding medium.
$(b)$ Name the materials of which the cell membrane and cell wall are composed.

$(a)$ List any two structural differences and two similarities between a plant cell and an animal cell.
$(b)$ What would happen if an animal cell is kept in distilled water for $24$ hours?

$(i)$ Why is the cell called the structural and functional unit of life?
$(ii)$ Why is the plasma membrane called a selectively permeable membrane?
$(iii)$ Name the factor which decides the movement of water across the plasma membrane.

$1 \, \mu m$ is equal to:

Identify the type of cell and write one characteristic feature for each of the following descriptions:
$(i)$ Large vacuole,nucleus pushed to the periphery.
$(ii)$ Cell does not burst even in a very dilute medium.
$(iii)$ Nuclear region is not well-defined and is known as the nucleoid.