Water movement seemed magical until I mapped out Transport of Water and Mineral Salts in three pathways:
- Apoplast: cell walls and intercellular spaces
- Symplast: cytoplasm linked by plasmodesmata
- Vacuolar: through vacuoles
I walked through root hairs absorbing soil solution, then watched my hand-drawn arrows converge at the endodermis (Casparian strip forces symplast entry). From there, the cohesion-tension theory explains how a continuous column of water is pulled up by transpiration at the leaf surface.
Sample SPM Question
“Explain the cohesion-tension theory in water transport.”
I broke my answer into two parts: (a) cohesion and adhesion generate a continuous water column, and (b) transpiration pull at the stomata creates negative pressure to draw water upward.
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