Answer: Osmosis.
- A Osmosis
- B Diffusion
- C Transpiration
- D Translocation
Correct answer: A. Osmosis
Explanation: Osmosis is the diffusion of water across a selectively permeable membrane, from a region of higher water potential to one of lower water potential.
Water can travel through cell walls (apoplast) or cell-to-cell through the cytoplasm (symplast) - but the Casparian strip at the endodermis blocks the apoplast route entirely, forcing everything through a selectively permeable membrane (symplast) before it can enter the xylem.
Concept context
Water and mineral absorption, the ascent of sap, transpiration, and phloem transport via the pressure flow hypothesis.