Symplastic transport dominates water and solute movement in leaves

Steps:

• Recall plant transport pathways: apoplast (cell walls, extracellular) vs. symplast (cytoplasm via plasmodesmata).
• In leaves, water and solutes primarily follow symplast for regulated uptake and distribution in mesophyll and vascular tissues.
• Eliminate apoplast options, as leaf endodermis is absent or minimal compared to roots.
• Confirm symplast enables selective movement through living cells, matching leaf physiology.

Why B is correct:

• Symplast pathway, by definition, allows water and solutes to move continuously through interconnected cytoplasm via plasmodesmata, providing control in leaf tissues.

Why the others are wrong:

• A: Lignified endodermis with apoplast pathway occurs in roots, not leaves.
• C: Cellulose cell walls enable apoplast movement, but osmosis drives water across membranes, not through walls.
• D: Suberin impermeabilizes cells (e.g., in root endodermis); diffusion alone lacks symplastic regulation.

Final answer: B