photosynthesis

• Reduced NADP


  Reduces/donates hydrogen
• Role of reduced NADP

  1. Reduces/donates hydrogen

  2. Converts PGA to PGAL
• Accessory pigments


  • Pass energy to chlorophyll a/primary pigment/reaction centre
  • Absorb light wavelengths that chlorophyll a/primary pigment/reaction centre does not
  • Form part of light-harvesting cluster of pigments/photosystem/antenna complex
• Method to separate and identify pigments

  1. Chromatography

  2. Place extract/sample on base line of paper/TLC plate

  3. Dry and repeat

  4. Place paper in solvent

  5. Measure distance travelled by solvent and pigment

  6. Calculate Rf value

  7. Compare Rf values against published values to identify pigments
• Structure and functions of chloroplast

  • Thylakoid(s)/granum/grana have large surface area/are many in number for light dependent reaction/photophosphorylation
  • Thylakoid membranes/grana have pigments/photosystems/LHC/electron carriers/ETC/ATP synthase to absorb (more) light
  • Stroma is a medium for light independent reaction/Calvin cycle and contains enzymes/RuBP/reduced NADP
  • Stroma is colourless so light reaches thylakoids and contains water
  • Contains DNA, ribosomes to make chloroplast proteins/proteins for photosynthesis
  • Contains starch grains/lipid droplets to store products of photosynthesis/(chemical) energy
  • Envelope provides compartmentalisation
• How rice is adapted to grow with roots submerged in water

  • Has aerenchyma in stem and roots to help oxygen move/diffuse to roots/submerged parts
  • Has shallow roots
  • Has air (film) trapped on underwater leaves
  • Has greater internode growth or leaves/flowers grow above water level
  • Growth regulated by gibberellin/ethene
  • Undergoes anaerobic respiration/alcoholic fermentation in roots/underwater/when submerged and is tolerant to high ethanol concentration due to alcohol dehydrogenase
• Light energy can be limiting factor in photosynthesis
• Reasons why light energy can be limiting factor in photosynthesis

  • Needed for light-dependent stage/photophosphorylation/photolysis/photoexcitation/photoactivation
  • To make reduced NADP/ATP
  • To open stomata (for CO2 to enter)
• Differences between cyclic and non-cyclic photophosphorylation

  • Similarities: Photoactivation of chlorophyll/excite electrons occurs in both, ETC involved in both, ATP produced in both

  Differences: Cyclic - only PSI involved, no reduced NADP/oxygen produced, no photolysis/oxygen-evolving complex involved, electrons emitted from PSI returned to PSI

  Non-cyclic - PSI and PSII both involved, reduced NADP/oxygen produced, photolysis/oxygen-evolving complex involved, electrons emitted from PSII replaced by water
• Limiting factor: process/photosynthesis, affected by more than one factor; rate is limited by the factor nearest its minimum value