Water uptake in roots via osmosis and water potential

Steps:

• Identify gap 1: Root hair cells have rigid cell walls, providing structural support while allowing water to reach the plasma membrane for absorption.
• Identify gap 2: Cytoplasm has lower water potential than soil, creating a gradient for water movement into cells.
• Identify gap 3 (direction): Water moves from higher (soil) to lower (cytoplasm) water potential.
• Identify gap 3 (process): This passive movement across a semi-permeable membrane is osmosis.

Why C is correct:

• Osmosis is the diffusion of water across a semi-permeable membrane from high to low water potential, matching the lower potential in root cytoplasm versus soil.

Why the others are wrong:

• A: Large walls don't facilitate absorption; larger potential would prevent influx; diffusion isn't specific to water across membranes.
• B: Permeable fits gap 1 but higher potential would drive water out, not in.
• D: Rigid fits gap 1 but higher potential blocks osmosis; active transport requires energy, not passive water uptake.

Final answer: C