Answer: root hairs.
- A root hairs
- B leaves
- C flowers
- D woody stem
Correct answer: A. root hairs
Explanation: Root hairs greatly increase the surface area for water absorption.
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.