Answer: cohesion-tension theory.
- A cohesion-tension theory
- B simple cell theory
- C microbial germ theory
- D lock-and-key theory
Correct answer: A. cohesion-tension theory
Explanation: The cohesion-tension theory accounts for the ascent of sap.
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.