Name the scientist who discovered cells. List any two single-celled (unicellular) organisms.

Give differences between diffusion and osmosis.

Name the longest cell of the human body.

$(a)$ 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?

Which part of the cell is called the brain of the cell?

Name the stain used to prepare slides like that of onion peel and cheek cell. Why is the use of stain necessary? Do all organelles absorb stain equally?