Optimizing Gas Exchange Diffusion

Steps:

• Recall Fick's law: diffusion rate proportional to concentration gradient and inversely proportional to diffusion distance.
• Steep concentration gradient maintains high partial pressure difference for faster gas movement.
• Short diffusion distance reduces path length, allowing quicker oxygen and CO2 exchange.
• Select option combining both features for maximum diffusion efficiency.

Why B is correct:

• Fick's law states diffusion rate = (area × constant × gradient) / distance; B maximizes rate with steep gradient and short distance.

Why the others are wrong:

• A: Long distance slows diffusion despite steep gradient.
• C: Shallow gradient limits diffusion despite long distance.
• D: Both shallow gradient and long distance minimize diffusion.

Final answer: B