Answer: Phloem as sucrose.
- A Xylem as sucrose
- B Phloem as sucrose
- C Xylem as glucose
- D Blood vessels
Correct answer: B. Phloem as sucrose
Explanation: Sucrose is the main form in which sugars are transported in the phloem from source (leaves) to sink (roots, fruits).
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.