A2 Biology Unit 4: Photosynthesis

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  • Created by: Ali
  • Created on: 25-12-12 11:49

Equation + Leaf Adaptations

  6CO2 + 6H20 + Energy ---> C6H1206 + 602

  Carbon dioxide + Water ---> Glucose + oxygen


- Large Surface Area -> absorb maximum amount of light

- Thin --> short diffusion distance so light can reach mesophyll cells

- numerous Stomata - for gaseous exchange

- Photosynthetic pigments - Chlorophyll A, Chlorophyll B, Carotene in Chloroplasts

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Light dependent reaction

  • in Thylakoid membranes

1. Chlorophyll absorbs light (photons), which boosts energy in a pair of electrons (photoexcitation)

2. Electrons leave chlorophyll and are taken up by electron carrier

3. Electrons lose energy at each level in electron transport chain

4. This energy is used to combine ADP and Pi = ATP

5. Photolysis of water occures.  H+ ions are taken up by NADP, forming reduced NADP, Oxygen is released as a waste gas in respiration, Electrons are replaced in the chlorophyll molecule.

6. ATP and reduced NADP are used in the next stage (Light independent)

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Light independent

  • aka the Calvin Cycle
  • in Stroma of Chloroplasts

1. Carbon dioxide combines with Ribulose Bisphosphate, forming two molecules of Glycerate 3-phosphate

2. ATP and reduced NADP from the dependent used to reduce activated glycerate 3-phosphate to triose phosphate.

3. One sixth of the triose phosphate is used to make glucose

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