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Photosynthesis

Photosynthesis. Stages of Photosynthesis. TEKS. 9B Compare the transfer of energy from one type of molecule to the next in respiration and photosynthesis. Chloroplasts. Thylakoid membrane Grana Stroma. Two Stages. Light Dependent Reactions Convert sunlight to ATP energy

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Photosynthesis

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  1. Photosynthesis Stages of Photosynthesis

  2. TEKS • 9B Compare the transfer of energy from one type of molecule to the next in respiration and photosynthesis

  3. Chloroplasts • Thylakoid membrane • Grana • Stroma

  4. Two Stages • Light Dependent Reactions • Convert sunlight to ATP energy • Occurs on thylakoid membrane • Light Independent Reactions • Uses ATP to make glucose • Occurs in stroma

  5. Light Dependent Reactions • Photochemical Reactions • Non-cyclic Electron Flow • Chemiosmosis

  6. Light Dependent Reactions • Photochemical Reactions • Light energy knocks electron off chorophyll in photosystems I and II

  7. Light Dependent Reactions Non-cyclic Electron Flow 1st stage • photosystem I passes 2 electrons to NADP+ • Photo I now short 2 electrons 2nd stage • Photosystem II passes 2 electrons to ETC in thylakoid membrane • H protons pumped across membrane • Electrons given to Photo I at end of ETC • Now Photo II short 2 electrons

  8. Light Dependent Reactions Non-cyclic Electron Flow, cont.. 3rd stage-photolysis • 2 electrons to photo II • 2 H protons pumped to inside of grana • Oxygen leaves plant as waste Net effect: NADPH + H produced H+ added to grana Oxygen released as waste

  9. Light Dependent Reactions • Chemiosmosis • H+ flows back through membrane via ATP synthetase • ATP produced

  10. Light Dependent Reactions • Products: • Oxygen • NADPH + H • ATP

  11. LDR

  12. Light Independent Reactions • CO2 + H+ + ATP used to make glucose

  13. LIR

  14. Factors Affecting Photosynthesis

  15. TEKS • 9B Compare the transfer of energy from one type of molecule to the next in respiration and photosynthesis

  16. Light Intensity • What effect does it have? • Rate increases then levels off • Why? • More reactants than enzymes… can’t keep up

  17. Temperature • What effect does it have? • Increases then decreases • Why? • Molecules move faster; therefore, more reactions • Enzymes denature at high temperatures

  18. Carbon Dioxide • What effect does it have? • Low conc. - slows • High conc. - slows • Why? • Low amounts of reactants slow rate

  19. Water • What effect does it have? • Little water slows rate • Why? • Stomata close

  20. Oxygen • What effect does it have? • Slows rate • Why? • Destroys pigments • Photorespiration

  21. CAM • Used by desert plants • Close stomata during day • CO2 gathered at night and stored • Rate of photosynthesis is low

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