Apoplast and Symplast Pathways in Plant Transport

Steps:

• Recall apoplast pathway moves water through cell walls and intercellular spaces without crossing membranes.
• Recall symplast pathway moves water through cytoplasm connected by plasmodesmata, crossing membranes.
• Evaluate statements: 1 (apoplast is faster, non-selective), 2 (symplast is selective via membranes), 3 (both used in roots), 4 (apoplast blocked at endodermis).
• Select option matching correct statements 1, 2, and 3.

Why B is correct:

• B includes statements 1, 2, and 3, aligning with definitions where apoplast is passive and fast, symplast is regulated, and both operate in root uptake.

Why the others are wrong:

• A includes 4, but apoplast isn't always blocked—symplast bypasses at Casparian strip.
• C omits 3, ignoring combined use in xylem loading.
• D omits 1 and 2, missing core pathway distinctions.

Final answer: B