Osmotic activity across plasma membranes is most closely related to
A) the distribution of proteins in the membrane
B) ionic differences between the ECF and ICF
C) differences in protein composition between the ECF and ICF
D) the distribution of proteins in the membrane and ionic differences between the ECF and ICF
E) the distribution of proteins in the membrane and differences in protein composition between the ECF and ICF

Question

Quizplus · Accepted Answer

Osmosis is the movement of water across a selectively permeable membrane from a region of low solute concentration to a region of high solute concentration. The solutes that primarily affect osmosis are ions, so the ionic differences between the extracellular fluid (ECF) and intracellular fluid (ICF) are most closely related to osmotic activity across plasma membranes. Choices A, C, and E are not directly related to osmosis. Choice D includes both distribution of proteins and ionic differences, but the latter is the more important factor for osmosis.

Osmotic Activity Across Plasma Membranes Is Most Closely Related to