Transpiration and Translocation

This lesson covers the two main transport processes in plants: transpiration (the movement of water) and translocation (the movement of dissolved sugars). Understanding how plants move substances is essential for the AQA GCSE Combined Science Trilogy specification (8464).

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Transpiration

What Is Transpiration?

Transpiration is the loss of water vapour from the surface of a plant, primarily through the stomata on the leaves.

The transpiration stream is the continuous flow of water through the plant:

graph TD
    A["Water absorbed from soil by root hair cells (by osmosis)"] --> B["Water moves through root cortex cells (by osmosis)"]
    B --> C["Water enters xylem vessels in the root"]
    C --> D["Water transported up through xylem in the stem"]
    D --> E["Water reaches the leaves via xylem in leaf veins"]
    E --> F["Water evaporates from cell surfaces inside the leaf"]
    F --> G["Water vapour diffuses out through stomata"]
    G --> H["Water vapour lost to the atmosphere (transpiration)"]

How Does the Transpiration Stream Work?