Guard cells Notes: Definitions & Explanations PDF | Download eBooks

Study Guard cells lecture notes PDF with biology definitions and explanation to study What are Guard cells?. Study guard cells explanation with biology terms to review biology course for online degree programs.

Guard cells Notes:

Guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore. When water is freely available, the guard cells turn turgid and stomatal pore is open wide. When the water availability is critically low, the guard cells become flaccid and stomatal pore closes. Carbondioxide and oxygen exchange also happens through stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Guard cells are specialized cells in the epidermis of leaves, stems and other organs that are used to control gas exchange. They are produced in pairs with a gap between them that forms a stomatal pore. The stomatal pores are largest when water is freely available and the guard cells turgid, and closed when water availability is critically low and the guard cells become flaccid. Photosynthesis depends on the diffusion of carbon dioxide (CO₂) from the air through the stomata into the mesophyll tissues. Oxygen (O₂), produced as a byproduct of photosynthesis, exits the plant via the stomata. When the stomata are open, water is lost by evaporation and must be replaced via the transpiration stream, with water taken up by the roots. Plants must balance the amount of CO₂ absorbed from the air with the water loss through the stomatal pores, and this is achieved by both active and passive control of guard cell turgor and stomatal pore size.

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