Answer: vessels and tracheids.
- A vessels and tracheids
- B the sieve tube cells
- C the companion cells
- D the guard cells
Correct answer: A. vessels and tracheids
Explanation: Xylem vessels and tracheids are dead cells that conduct water.
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.