Question

Why plasma membarane is called selectively preamble membarane?how do substances lke CO2 And water move in and out of the cell

Answer 1

Plasma membrane is known as selectively preamble membrane because it allows only certain substances to pass through while it prevents others.

CO2 and water move in and out of the cell by diffusion from the region of high concentration to low concentration. When the concentration of CO2
and water is higher in external environment than that in the cell, CO2 and water moves incident the cell.

Hope this helps.

Answer 2

The membrane is called selectively permeable membrane because it allows selective materials like gases water and wastes not all to move in and out of a cell.
Similarly, when its concentration is lower in the cell as compared to outside the cell, it moves into the cell. Water also moves in and out of the cell by the same principle of difference of concentration, but the process through which water moves across a selectively permeable membrane is called osmosis.