Though cells may differ in shape and size, all of them have the same basic structure. The main parts of any cell are cell membrane, cytoplasm, and nucleus.
CELL MEMBRANE
It is the outermost covering of a cell, which protects the cell.
It is a porous membrane and is selectively permeable.
This means that cell membrane allows certain substances to pass through, while restricting the absorption of other substances.
Plant cells have additional layer outside the cell membrane, called cell wall.
Animal cells lack the cell wall.
IMPORTANT QUESTIONS
Why is cell membrane called selectively permeable membrane?
Cell membrane is called selectively permeable membrane because it allows certain substances to pass through, while restricting the absorption of other substances.