Question

bio-201 topic 2: cell physiology & tissues
practice it
what makes the cell membrane selectively permeable to na+ and k+ ions?
cholesterol molecules embedded in the membrane
concentration gradients of other ions
ion channels that are specific to each ion
transporter proteins that actively pump ions across the membrane
physical size of the ions

Explanation:

Cell membranes have ion - specific channels. For sodium (Na+) and potassium (K+) ions, there are specific ion channels that allow their selective passage, enabling functions like nerve impulse transmission and maintaining cell potential. Cholesterol affects membrane fluidity, ion concentration gradients drive diffusion but don't make the membrane selectively permeable, transporter proteins actively move ions but not what gives selectivity in this context, and ion size isn't the main factor for this selectivity.

Answer:

Ion channels that are specific to each ion