Photosynthesis

    Cards (7)

    • Diffusion is essential to photosynthesis for the movement of molecules of:

      -CO2 from outside the leaf inside the green leaf cells

      -O2 from inside the green leaf cells to outside the leaf
    • What do plant cells need glucose for?

      -Respiration which provides chemical energy for cellular processes including:

      -Cell division

      Protein Synthesis

      Excess can be converted into:

      -STARCH which is a storage carbohydrate (can be broken down to
      glucose again when the cell needs a source of energy).

      -CELLULOSE which is a structural carbohydrate (used to build
      plant cell walls).
    • 2 stages – take place in chloroplast

      Light reactions

      -splitting of water

      Carbon fixation

      -CO2 combined with H to make glucose
    • Light Reactions

      -Solar (light) energy is trapped by chlorophyll and converted to chemical
      energy.

      -This energy is used to split molecules of water into hydrogen and oxygen.

      -Chlorophyll also provides enough energy for the regeneration of ATP
      from ADP and Pi which is used in Stage 2 (Carbon Fixation).
    • Light Reactions (cont'd.)

      -The oxygen is released as a by-product and leaves the cell by diffusion.

      -The hydrogen combines with a hydrogen acceptor. When loaded with
      hydrogen, the acceptor is said to be reduced. The Hydrogen is also
      needed in Stage 2 (Carbon Fixation).
    • Carbon Fixation

      -Also occurs in chloroplasts.

      -A series of enzyme controlled reactions which form a cycle.

      -Allows the carbon in CO2 to become ‘fixed’ into carbohydrate by
      combining with the hydrogen produced during the light reactions.

      -Carbon fixation results in the formation of glucose (sugar).

      -Energy is supplied by the ATP from stage 1.
    • Limiting Factors of Photosynthesis

      • Temperature
      • Light intensity
      • CO2 Concentration
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