The ability of the cell membrane to act as a selective barrier depends upon

The correct answer is (D) All of these.

The cell membrane’s ability to act as a selective barrier depends on a combination of factors:

– (A) Lipid composition: The phospholipid bilayer structure and the types of lipids present influence the membrane’s permeability and fluidity.
– (B) Pores: Small molecules can pass through the membrane via pores or channels, such as aquaporins for water or ion channels for specific ions.
– (C) Specialized mediated transport systems: Transport proteins, like carriers or pumps, facilitate the movement of specific molecules across the membrane, often against concentration gradients.