Question

1. which of the following is moved across a cell membrane through the process of facilitated diffusion?

water

glucose

sodium

calcium

Explanation:

Facilitated diffusion is a type of passive transport that requires membrane - spanning proteins (channels or carriers) to move substances across the cell membrane. Water can move through aquaporins (a form of facilitated diffusion in some cases, but also simple diffusion in others), but glucose is a polar molecule that is too large to pass through the lipid bilayer by simple diffusion. It typically moves across cell membranes (e.g., in red blood cells) via glucose transporters (GLUT proteins), which is a form of facilitated diffusion. Sodium and calcium ions usually move through ion - channel - mediated facilitated diffusion or active transport (depending on the concentration gradient and other factors). But among the options given, glucose is a classic example of a molecule that is moved across a cell membrane through facilitated diffusion in many cell types.

Answer:

glucose