Question

use the image below to answer the following questions
identify, giving a reason, a, b, and c as diffusion, facilitated diffusion, or active transport.

Explanation:

• A (Diffusion): Particles move from high to low concentration directly through the phospholipid bilayer (no protein involved), following the concentration gradient. This is simple diffusion, where small, non - polar or lipid - soluble molecules pass through the membrane without assistance.
• B (Facilitated Diffusion): Particles move from high to low concentration but use protein channels or carriers (the oval structures in the membrane). This is facilitated diffusion as it requires a transport protein to move substances down their concentration gradient, and no energy (ATP) is used.
• C (Active Transport): Particles move from low to high concentration (against the gradient) and ATP is used (shown by the ATP symbol). Active transport requires energy to move substances against their concentration gradient, often with the help of a carrier protein.

Answer:

• A: Diffusion. Reason: Molecules move from high to low concentration directly through the lipid bilayer (no protein, down concentration gradient).
• B: Facilitated Diffusion. Reason: Molecules move from high to low concentration via membrane proteins (down gradient, no ATP).
• C: Active Transport. Reason: Molecules move from low to high concentration (against gradient) with ATP energy and a membrane protein.