Answer: Cuticle.
- A Cuticle
- B Cortex
- C Pericycle
- D Endodermis
Correct answer: A. Cuticle
Explanation: A small amount of water is lost straight through the leaf's waxy cuticle - this is cuticular transpiration.
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.