Photosynthetic Reactions

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    Bea

    Cards (10)

    • Light-Dependent
      The light-dependent reactions of photosynthesis occur in the thylakoid membranes and include:
      1. Photon Absorption: Light energy excites electrons in chlorophyll.
      2. Water Splitting: Light energy splits water into oxygen, protons, and electrons.
      3. Electron Transport Chain (ETC): Excited electrons move through the ETC, releasing energy.
      4. ATP Formation: Energy from the ETC creates a proton gradient that drives ATP synthesis.
      5. NADP+ Reduction: Electrons and protons reduce NADP+ to NADPH.
      These reactions convert light energy into ATP and NADPH, fueling the Calvin cycle.
    • Q: Where do the light-dependent reactions of photosynthesis occur?
      A: thylakoid membranes of chloroplasts.
    • Q: What is the first step in the light-dependent reactions?
      A: Photon absorption, where light energy excites electrons in chlorophyll.
    • Q: What happens during the photolysis of water in the light-dependent reactions?
      A: Water molecules are split into oxygen, protons (H+ ions), and electrons.
    • Q: What is the electron transport chain (ETC) in photosynthesis?
      A: A series of proteins in the thylakoid membrane that transfer excited electrons, releasing energy
    • Q: How is ATP formed during the light-dependent reactions?
      A: Energy from the electron transport chain creates a proton gradient that drives ATP synthase to convert ADP to ATP.
    • Q: What molecule is reduced to form NADPH in the light-dependent reactions?
      A: NADP+ is reduced by the electrons at the end of the electron transport chain, forming NADPH.
    • Q: What are the main products of the light-dependent reactions?
      A: ATP and NADPH, which are used in the Calvin cycle.
    • Q: What byproduct is released during the light-dependent reactions?
      A: Oxygen (O₂), produced from the splitting of water.
    • The Calvin Cycle, occurring in the stroma of chloroplasts, involves:
      1. Carbon Fixation: CO₂ is fixed to RuBP by RuBisCO, forming 6 Carbon-Compound which splits into 2x 3 Carbon Compound Molecules
      2. Reduction: ATP and NADPH convert 3-phosphoglycerate into G3P (glyceraldehyde-3-phosphate).
      3. Regeneration: Some G3P regenerates RuBP; the rest forms glucose and other carbohydrates.
      It synthesizes glucose using ATP and NADPH from the light-dependent reactions.
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