Light-Dependent Reaction:

  • Chlorophyll absorbs light, leading to photoionisation of chlorophyll.
  • Energy from electrons released during photoionisation is conserved in the production of ATP and reduced NADP.
  • ATP production involves electron transfer associated with the electron transfer chain, proton passage across chloroplast membranes, and catalysis by ATP synthase (chemiosomotic theory).
  • Photolysis of water produces protons, electrons and oxygen.
  • Light-dependent reaction provides reduced NADP and ATP for light-independent reaction.

Light-Independent Reaction:

  • Carbon dioxide reacts with ribulose bisphosphate (RuBP) to form two molecules of glycerate 3-phosphate (GP), facilitated by enzyme rubisco.
  • ATP and reduced NADP from light-dependent reaction reduce GP to triose phosphate.
  • Some of the triose phosphate regenerates RuBP in the Calvin cycle.
  • Some triose phosphate is converted to useful organic substances.

Other Important Information:

  • Should be able to identify environmental factors that limit photosynthesis rate.
  • Should be able to evaluate data on agricultural practises used to mitigate limiting factors’ effects.
  • Photosynthesis rate investigation methods and techniques should be revised.
  • Ability to interpret graphs representing multiple limiting factors is important.

Practical Skills:

  • Chromatography use to examine plant pigments.
  • Investigating the impacts of factors on dehydrogenase enzymes.