Plant Water Relation — Important Questions

Imbibition, Diffusion, Osmosis

Water absorption by root hairs occurs through three sequential processes: imbibition (by cell wall), diffusion (through cell wall), and osmosis (across plasma membrane). Active transport and transpiration are not directly involved in water absorption.

Diffusion Pressure Deficit

DPD stands for Diffusion Pressure Deficit, which represents the reduction in diffusion pressure of water in a solution compared to pure water. It is now commonly referred to as water potential.

Apoplast pathway, Symplast pathway, Vacuolar pathway

Water moves across the root via apoplast pathway (through cell walls), symplast pathway (through plasmodesmata), and transmembrane pathway (across cell membranes). Transmembrane is part of symplastic movement.

Active absorption by root cells

Root pressure develops due to active absorption of water by living cells of the root. This creates a hydrostatic pressure that forces water into xylem and helps in upward movement.