Uptake Mechanisms in Root Hair Cells

Steps:

• Water moves across the cell membrane from higher to lower water potential in soil.
• Ions often have higher concentrations inside cells than in soil, requiring energy to enter.
• Osmosis is passive diffusion for water; active transport uses ATP for ions against gradients.
• Match processes to options: water via osmosis, ions via active transport.

Why D is correct:

• Water enters by osmosis, the passive movement down a water potential gradient; ions by active transport, which pumps substances against concentration gradients using ATP.

Why the others are wrong:

• A: Water enters passively by osmosis, not active transport requiring energy.
• B: Water enters by osmosis, not active transport; ions require active transport, not osmosis.
• C: Ions enter by active transport against gradients, not osmosis which is passive.

Final answer: D