Matching Molecular Transport Processes

Steps:

• Description 1 indicates passive movement down a concentration gradient, typical of diffusion.
• Description 2 indicates movement against a concentration gradient, requiring energy, which defines active transport.
• Description 3 specifies passive movement down a gradient across a partially permeable membrane, characteristic of osmosis for water molecules.
• Compare options: only D correctly pairs 2 with active transport and 3 with osmosis.

Why D is correct:

• Active transport is defined as moving molecules from low to high concentration against the gradient, while osmosis is the net movement of water from high to low concentration across a partially permeable membrane.

Why the others are wrong:

• A: 1 describes general diffusion, not osmosis; 3 describes osmosis, not active transport.
• B: 1 describes diffusion, not osmosis; 3 is osmosis (water-specific), not general diffusion.
• C: 3 describes osmosis, not active transport.

Final answer: D