Membrane proteins serve many functions, one of which is transportation of substances across a membrane. If a cytologist placed cells into an environment where a chemical blocks the function of carrier proteins, which process will be affected? (A) osmosis. (B) diffusion. (C) facilitated diffusion. (D) active transport. (E) exocytosis.

Facilitated diffusion will be affected since this process specifically relies on carrier proteins to help transport substances across the cell membrane. When these proteins are blocked, molecules that would normally pass through with assistance can’t get to where they need to go, causing a traffic jam of types on the cellular highway! Active transport may also be impacted indirectly, as it often involves the use of proteins to move substances against their concentration gradient. However, the key process being directly hindered in this scenario is definitely facilitated diffusion. Time to get those proteins back in action!