Question

question 19 which of the following transport mechanisms moves substances against a concentration gradient? a facilitated diffusion b carrier diffusion c osmosis d simple diffusion e active transport

Explanation:

• Facilitated diffusion (A): Moves substances down the concentration gradient with the help of transport proteins, no energy required.
• Carrier diffusion (B): A type of facilitated diffusion, also moves down the gradient.
• Osmosis (C): Movement of water down its concentration gradient (towards higher solute concentration), passive.
• Simple diffusion (D): Passive movement of substances down their concentration gradient.
• Active transport (E): Requires energy (e.g., ATP) to move substances against their concentration gradient (from low to high concentration).

Answer:

E. active transport