Photosynthesis

• Photosynthesis equation:


  6CO2 + 6H20 + energy -> C6 H12 O6 + 6O2
• What is a photoautotroph?

  Organism can make its own food using light energy. Process of photosynthesis same in all photoautotrophs, suggesting they all evolved from common ancestor.
• Aerobic respiration equation:


  C6 H12 O6 + 6O2 -> 6CO2 + 6H2O + energy
• What does anaerobic respiration in plants & yeast produce?

  Ethanol & CO2 & releases energy
• What does anaerobic respiration in humans produce?

  Lactate & releases energy
• Structure of ATP:


  Adenine, ribose sugar & 3 phosphate groups. Chemical energy stored in phosphate bonds between the 3 groups. Energy released from glucose in respiration used to make ATP.
• ATP properties:


  Stores/releases only small, manageable amount of energy at a time so no energy wasted as heat, small, soluble molecule (easily transported), easily broken down (energy released instantaneously), quickly remade, can make other molecules more reactive by transferring Pi (phosphorylation) & can't leave cell (immediate supply of energy).
• What is the compensation point for light intensity?

  Level of light intensity at which rate of photosynthesis exactly matches rate of respiration.
• How to work out compensation point?

  Measure rate at which O2 produced & used by plant at different light intensities. Photosynthesis produces O2 & respiration uses it, so compensation point= light intensity at which O2 used as quickly as it's being produced. Rate of CO2 production can also be measured.
• What are the 2 stages of photosynthesis?

  Light dependent reaction & the Calvin Cycle (light independent reaction)
• What is a coenzyme?

  Electron + proton carrier
• What is chemiosmosis?


  Diffusion of protons down electrochemical gradient across ATP synthase to generate ATP.
• Where are photosynthetic pigments found?

  Thylakoid membranes attached to proteins. Pigments= chlorophyll A, B & Carotene.
• What is a photosystem?

  Protein + photosynthetic pigment
• What 2 photosystems are used by plants to absorb light?

  PSI (700nm wavelength) & PSII (680nm wavelength).
• What happens at PSII?

  Light energy absorbed by PSII. Light energy excites electrons in chlorophyll & electrons move to a higher energy level. These high energy electrons move along electron transport chain to PSI.
• In light dependent reaction, light energy absorbed by photosystems used for...

  Making ATP from ADP & Pi (photophosphorylation), making reduced NADP from NADP & splitting water into protons, electrons & oxygen (photolysis).
• What happens in non-cyclic photophosphorylation?

  ATP, reduced NADP & O2 produced. Photosystems in thylakoid membranes linked by electron carriers (proteins that transfer electrons). Photosystems & their electron carriers form an electron transport chain (chain of proteins through which excited electrons flow). Excited electrons lose energy as they move along electron transport chain.