Photosystems and Photophosphorylation Quiz
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Questions and Answers

What are the primary products of photosynthesis?

  • Oxygen and glucose (correct)
  • Oxygen and water
  • Carbon dioxide and ATP
  • Glucose and NADPH

    • Which of the following best describes the Calvin cycle?

  • It occurs in the thylakoid membrane and produces oxygen.
  • It converts ATP back into ADP for energy conservation.
  • It relies solely on light absorption to function.
  • It fixes carbon dioxide into organic compounds. (correct)

    • In which part of the chloroplast does the Calvin cycle take place?

  • Thylakoid membrane
  • Stroma (correct)
  • Inner membrane
  • Cytoplasm

    • Which statement accurately describes the light-dependent reactions?

    <p>They generate ATP and NADPH from water and light.</p> Signup and view all the answers

    How do photosynthesis and cellular respiration relate to each other?

    <p>They are complementary, with photosynthesis producing oxygen for cellular respiration.</p> Signup and view all the answers

    Which of the following is NOT a reactant in the photosynthesis process?

    <p>Oxygen</p> Signup and view all the answers

    What role does water play in photosynthesis?

    <p>It acts as a reactant that is split to release oxygen.</p> Signup and view all the answers

    During photosynthesis, which molecule is ultimately produced through the fixation of carbon dioxide?

    <p>Glyceraldehyde-3-phosphate (G3P)</p> Signup and view all the answers

    What is the primary purpose of the light-dependent reactions in photosynthesis?

    <p>To produce ATP and NADPH</p> Signup and view all the answers

    Which component within a photosystem is responsible for losing an electron when excited?

    <p>Special pair of chlorophyll a molecules</p> Signup and view all the answers

    What occurs during resonance energy transfer in a photosystem?

    <p>Excited pigments pass energy to neighboring pigments</p> Signup and view all the answers

    In non-cyclic photophosphorylation, where do the electrons ultimately come from?

    <p>Water molecules</p> Signup and view all the answers

    What distinguishes Photosystem II (PSII) from Photosystem I (PSI)?

    <p>PSII has a special pair with a P680 chlorophyll</p> Signup and view all the answers

    Which of the following statements about light-harvesting complexes is correct?

    <p>They help funnel energy to the reaction center from absorbed light</p> Signup and view all the answers

    What is the result of light absorption during non-cyclic photophosphorylation?

    <p>Addition of electrons to NADP+</p> Signup and view all the answers

    Which photosystem primarily interacts with the electron transport chain following PSII?

    <p>Photosystem I</p> Signup and view all the answers

    What is the initial role of light energy in photosystem II?

    <p>It leads to the boosting of an electron in P680.</p> Signup and view all the answers

    What molecule is produced as a byproduct from the splitting of water during photosynthesis?

    <p>Oxygen</p> Signup and view all the answers

    What process harnesses the flow of protons to synthesize ATP?

    <p>Chemiosmosis</p> Signup and view all the answers

    During the light-dependent reactions, where does the high-energy electron travel after leaving photosystem II?

    <p>To the reaction center of photosystem I.</p> Signup and view all the answers

    What is the primary function of NADPH in photosynthesis?

    <p>To accept and carry high-energy electrons.</p> Signup and view all the answers

    Which pathway does not result in the formation of NADPH?

    <p>Cyclic photophosphorylation</p> Signup and view all the answers

    How is ATP produced during the light reaction phase of photosynthesis?

    <p>By pumping protons through ATP synthase.</p> Signup and view all the answers

    What happens to the electron that is lost from P700 in photosystem I?

    <p>It is replaced by an electron from photosystem II.</p> Signup and view all the answers

    Study Notes

    Photosystems

    • Photosystems contain proteins, pigments, and chlorophylls, and function to harvest light
    • Photosystems are optimized to capture light energy
    • Light-harvesting complexes:
      • Contain proteins and pigments like chlorophylls
      • Capture light energy
    • Reaction center:
      • Contains a special pair of chlorophyll a molecules (often called the special pair)
      • The special pair can lose an electron when it absorbs light and pass it to the primary electron acceptor

    Photosystem Types

    • Photosystem II (PSII):
      • Special pair: P680
      • Primary receptor: Pheophytin
      • Source of electrons: Water molecules
    • Photosystem I (PSI):
      • Special pair: P700
      • Primary receptor: A0
      • Source of electrons: Electron transport chain from PSII

    Non-Cyclic Photophosphorylation

    • Definition: The movement of electrons from water to NADPH through PSII and PSI, generating ATP.
    • Requires sunlight absorption twice:
      • Once in each photosystem
    • Products: ATP and NADPH
    • Process:
      • Electrons are removed from water molecules
      • Electrons are passed through PSII and PSI
      • Electrons end up in NADPH

    Cyclic Photophosphorylation

    • Definition: Electrons cycle back to the first part of the electron transport chain, repeatedly cycling through PSI.
    • Does not generate NADPH: Electrons are routed away from NADP+ reductase.
    • Products: ATP
    • Process:
      • Electrons flow down the electron transport chain
      • Protons are pumped into the thylakoid interior
      • Electrons return to the first part of the electron transport chain

    Light Absorption of PSII

    • Energy is passed from pigment to pigment until it reaches the reaction center
    • Energy is transferred to P680 and boosts an electron to a high energy level
    • The high-energy electron is transferred to an acceptor molecule
    • The special pair's electron is replaced with an electron from water
    • Splitting of water releases oxygen as a byproduct

    Light Absorption of PSI

    • The electron arrives at photosystem I and joins the P700 special pair of chlorophylls
    • Light energy is absorbed by pigments and passed to the reaction center
    • The special pair's electron is boosted to a very high energy level and transferred to an acceptor molecule
    • The special pair's missing electron is replaced by a new electron from PSII (arriving via the electron transport chain)

    Electron Transport Chains

    • Release energy as electrons move through
    • Energy is used to drive pumping of H+ ions into the thylakoid interior.
    • The H+ gradient created is then used to make ATP

    ATP Synthesis

    • The flow of H+ ions through ATP synthase generates ATP from ADP and phosphate
    • This process is called chemiosmosis

    NADPH Formation

    • The high-energy electron travels down a short second leg of the electron transport chain
    • The electron is passed to NADP+ (along with a second electron from the same pathway) to make NADPH

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    Related Documents

    Photosynthesis PPT PDF

    Description

    Test your knowledge on the roles of photosystems in light absorption and energy conversion. This quiz covers the structure and function of both Photosystem I and II, as well as the process of non-cyclic photophosphorylation. Perfect for students studying plant biology or photosynthesis.

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