Absorption, Transport and Water Loss in Plants

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Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration, down the concentration gradient. It occurs without energy input and is passive. For exa…

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Osmosis is the diffusion of water molecules from a region of higher water concentration (or higher water potential) to a region of lower water concentration through a semi-permeable membrane. It is a …

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Water potential (ψ) is the tendency of water to move from one place to another. It is measured in megapascals (MPa). Pure water has the highest water potential, set at zero. Adding solutes lowers wate…

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Root hairs are thin, elongated extensions of root epidermal cells. They increase the surface area for absorption of water and minerals from the soil. Water enters root hairs by osmosis because the cel…

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The two pathways are: (1) Apoplast pathway – water moves through cell walls without crossing membranes, and (2) Symplast pathway – water moves through the cytoplasm of cells via plasmodesmata. The Cas…

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Root pressure is the positive pressure developed in the xylem of roots due to the active absorption of water and minerals. It pushes water upward and can cause guttation. Root pressure is weak and onl…

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The cohesion-tension theory explains how water moves upward in xylem against gravity. Transpiration creates a tension (negative pressure) in the leaf, pulling water upward. Water molecules stick toget…

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Imbibition is the absorption of water by hydrophilic colloids in plant cells, such as proteins and cellulose in dry seeds. It causes swelling and is the first step in seed germination. For example, dr…