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Science

Transport in plants

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Adaptations

A healthy plant must balance its water loss from the leaves with its water uptake through the roots. Transpiration provides plants with water for:

  • Cooling
  • Photosynthesis
  • Support
  • Movement of minerals

However, the plant's cells will become flaccid and the plant will wilt if it loses too much water. The root hair cells provide a large surface area for efficient uptake of water by osmosis.

Root hair cell

The structure of a leaf is adapted to reduce excessive water loss. Its adaptations include:

  • A waxy cuticle
  • Only having a small number of stomatastomata: Tiny holes in the epidermis (skin) of a leaf - usually on the undersides of leaves. They control water loss and gas exchange by openng and closing. Singular is stoma on the upper surface

Adaptions - Higher tier

Transpiration and water loss from leaves happen because of the way that leaves are adapted for efficient photosynthesis. The flat, thin shape of a leaf, its spongy mesophyll layer and stomata are adaptations that also allow water loss from the leaf. Features involving the guard cellsguard cell: Specialised cell which controls the opening and closing of stomata in a green plant's leaves around the stomata provide a way to reduce excessive water loss.

The size of the stomatal opening can be altered by the plant in response to the availability of water and the light intensity. For example, in conditions where there is plenty of water and bright light:

  • Chloroplasts make sugars at a high rate
  • Water enters the guard cells from other cells by osmosis
  • The guard cells become turgid
  • The stomatal opening gets bigger

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