Question

question 15 glucose, a small uncharged molecule, can pass through the cell membrane, but sodium ions do not pass through the membrane easily. what is the most accurate explanation for these findings? a cell membranes have carrier proteins for glucose but not for sodium. b the cell membrane is semi - permeable. c the membrane potential makes it difficult for sodium ions to diffuse across the membrane. d the sodium - potassium pump keeps sodium inside the cell.

Explanation:

Cell membranes are semi - permeable, meaning they allow certain substances to pass through while restricting others. Glucose can pass through with the help of carrier proteins but sodium ions are restricted due to their charge and size. The sodium - potassium pump actively transports sodium out of the cell and potassium in, maintaining a concentration gradient. The membrane potential also affects ion movement. The semi - permeability of the cell membrane is the key property here.

Answer:

B. The cell membrane is semi - permeable.