GCSE Biology (AQA)

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Stomata & Guard Cells

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Organisation Plant Tissues, Organs and Systems

Stomata & Guard Cells

3:12 Plant Leaf Structures
Spec 4.2.3.1 4.2.3.2
Previous Leaves Next Investigating Stomata
  • Stomata are small openings on the lower epidermis of a leaf.
  • The singular form of stomata is stoma.
  • Stomata are surrounded by guard cells which help open and close these pores.
  • Guard cells control the size of the stomatal opening.
  • Stomata allow for the diffusion of carbon dioxide into the leaf and oxygen out of the leaf, essential for photosynthesis.
  • The movement of water vapor out of the leaf through stomata is called transpiration.
  • Guard cells control gas exchange and water loss by adjusting the size of the stomatal pores.
  • When guard cells are swollen, the stoma opens; when they lack water, the stoma closes.

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