Which statement best describes osmosis in plant roots?

• A. Osmosis drives water from higher to lower water potential, increasing root turgor as water enters.
• B. Osmosis requires energy input from the root.
• C. Osmosis moves water from soil into roots against the water potential gradient.
• D. Osmosis moves water out of roots into soil.

Answer: (A)

Water moves by osmosis from regions of higher water potential to lower water potential across a selectively permeable membrane. In plant roots, soil water has a higher water potential than the interior of root cells, where solutes lower the water potential. As water enters the root cells, turgor pressure increases, helping keep the plant rigid and supporting growth. Osmosis is passive, not requiring energy input, because it relies on the natural gradient in water potential.