Answer:
1. The plasma membrane allows some substances to enter or leave a cell more easily than others.
Explanation:
The plasma membrane is selectively permeable membrane that surrounds the cell cytoplasm and organelle of cell. The plasma membrane is selectively permeable because it allows some substance to pass through it more easily by simple diffusion and some substance through carrier and channel proteins.
The plasma membrane allows selective molecules to pass through it. Small and lipophilic molecules can cross the membrane by diffusion but large and ionic molecules require transport proteins. Some transport proteins need ATP energy to transport molecules across the membrane. Therefore the right answer is 1.
