Question

Plasma membrane is a
A. Permeable
B. Selectively permeable
C. Impermeable
D. Semi-permeable

Answer 1

Hint:Plasma membrane is also called cell membrane. The plasma membrane or the cell membrane surrounds the cell and encloses its contents of cytoplasm and nucleoplasm. It separates the cell from the outside environment.

Complete answer: Permeability can be defined as the degree of diffusion of liquids, gases, and other dissolved substances through a membrane. This ability of a substance to regulate passage through the membrane is called permeability. Depending upon the permeability of the membrane, it is classified as a freely permeable membrane, selectively permeable membrane, impermeable membrane, and a semi-permeable membrane. The selectively permeable membrane or differentially permeable membrane allows passage of only selected molecules to pass through it. Some of the examples of the selectively permeable membrane are the membrane that surrounds the subcellular organelles, tonoplast, and cell membrane. Cellophane is an example of a non-living selectively permeable membrane. The rate of permeability of different molecules differs in selectively permeable membranes. Plasma membrane which is also called cell membrane is selectively permeable as it only allows selected molecules of solute and solvent to pass through it.

So, option B is the correct option.

Note: Freely permeable membrane allows passage of various molecules through the membrane. The cell wall is an example of a freely permeable membrane. The impermeable membrane does not allow any kind of movement through it. A Cutinized cell wall is an example of an impermeable membrane. A semi-permeable membrane allows passage of only solvent molecules to pass through it. The animal bladder, parchment membrane are examples of semi-permeable membranes. Apart from natural membranes, artificial membranes are also present that are semi-permeable in nature.