Gas exchange in plant

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Key words

key terms =

  • leaf
  • stem
  • waxy cuticle
  • upper/lower epidermis
  • nucleus
  • vacule
  • chloroplasts
  • mesephyll cells
  • guard cells
  • stomatal pore
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Key facts

Carbon dioxide is used by plantsdo do photosynthesis

Plants respire all the time

Oxygen is the gas they need to respire

The plants get these gases from the atmosphere

The gases diffuse through the stomata

Water vapour often diffuses through the leaf

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leafs are good for gas exchagnge ...

they are thin (large surface area:volume ratio)

Air space in mesophyll layer allows for efficient movement of diffusion of gases

Stomata with guard cells that open and close to allow for exit/entry of gases

Diffusion path to every cell is short

Every cell has a good supply of oxygen and carbon dioxide

Diffusion in air not water, therefore is quicker

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Stomata

Stomata pore is formed by 2 guard cells

Day (light) guard cells become targid and open for gas exchange

Night (dark) guard cells lose water and is closed so stops gas exchange

Targid cells = water enters by osmosis vacule swells and pushes against cell walls

Flaccid cells =water lost from cell, vacuole shrinks cell loses shape

  • Guard cells potosynthesis using energy from sunlight and produce glucose. This lowers the water potential compared to the neighbouring epidermal cell. This means water moves from the epidermal cell
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