Transpiration and Photosynthesis.

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    • #17784

      How does Photosynthesis affect Transpiration?

    • #115201

      Photosynthesis requires water to happen. The water is photolysed (split apart) using the energy gained from sunlight, which will draw more up through the xylem from the roots. However more significantly for photosynthesis to take place there needs to be gas exchange through the stomatal pores predominantly found on the lower sides of the leaf.

      If these pores are closed very little water can evapourate (transpire). So if there are low levels of photosynthesis (say, at night) then there will also be relatively low levels of transpiration. The water just cannot get out. However if the pores are left open a much greater volume of water can be lose this way.

      You can therefore assume factors that increase the rate of photosynthesis (higher temperature, light intensity etc.) will also increase the rate of transpiration.

    • #115204

      Seriously? Do you have any idea, what is the concentration of water? Even if we assume that the cell is crowded, I’m sure the metabolism doesn’t significantly influence concentration of water.

      Shouldn’t be the question the other way – how does transpiration affect photosynthesis?

    • #115210

      JackBean, if you’re replying to me then it could be the other way round but in this circumstance it wasn’t. It was a question on a mock exam paper which I have now found the answer to, it was basically this:
      More photosynthesis
      More CO2 absorbed
      Which therefore increases the stomatal opening.

    • #115228

      Try to consider the light and dark reaction. A plant it active during the day and photosynthsise and in the process release excess H2O contents to the atmosphere (transpiration). So the phenomenom are complimentary.

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