Give a specific example of how the cell membrane is selectively permeable?

Answer 1

Cell membrane is selectively permeable because it only allows those materials, ions to enter into the cell, which are necessary and not harmful for it. The substances which are lipid soluble cross it more easily than others, therefore, it regulates the flow of ions and materials to maintain a definite gradient. Many small gas molecules, water, glucose etc being neutral can easily cross while ions, being charged particles have some difficulty in crossing.

Answer 2

Here is one specific example:

The flow of sodium and potassium ions across the plasma membrane of many cells is mediated by a protein that spans the membrane, called NaK ATPase. It uses energy provided by ATP to pump the two ions differentially across the cell membrane so that, in human extracellular tissue fluids Na+ tends to predominate, whereas in the cytoplasm of the living cell, K+ concentration is much higher.

Thus, the selective permeability of the plasma membrane to Na+ and K+ is mediated by the NaK ATPase.

Answer 3

A example of how a cell membrane is selective is when the phospholipids will choose to let food in and waste out. Good Luck!

Answer 4

The cellular membrane lets in and lets out things that the cell needs, such as Water, or glucose... things like that. and it lets out things the cell is done with, in some cases waste. Hope this helps