Shared passive movement in diffusion and osmosis

Steps:

• Define diffusion as net movement of any particles from high to low concentration.
• Define osmosis as net movement of water across a semi-permeable membrane from high to low water concentration.
• Identify common feature: both processes move substances down their concentration gradients without energy input.
• Eliminate options not shared by both: diffusion applies to various particles and states, not just water or liquids, and requires no cellular energy.

Why A is correct:

• Both follow Fick's law of diffusion, where net flux occurs down the concentration gradient until equilibrium.

Why the others are wrong:

• B: Diffusion involves any particles (e.g., gases like oxygen), not always water.
• C: Diffusion occurs in gases, liquids, and solids; osmosis requires a membrane but not exclusively liquids.
• D: Both are passive processes, relying on kinetic energy, not cellular ATP.

Final answer: A