5.1.1 Light-Dependent Reactions

    Cards (101)

    • What are the three products of the light-dependent reactions?
      Oxygen, ATP, NADPH
    • The light-dependent reactions occur in the thylakoid membranes of chloroplasts.
    • Thylakoids are stacked into structures called grana
    • What type of light does chlorophyll a absorb most effectively?
      Blue-violet and red
    • Chlorophyll b broadens the light spectrum by absorbing blue and yellow-green light.
    • What is the role of carotenoids in photosynthesis?
      Light absorption and photoprotection
    • Main steps of the light-dependent reactions
      1️⃣ Light absorption by pigments
      2️⃣ Electron transfer through ETC
      3️⃣ ATP and NADPH production
    • The light-dependent reactions take place in the thylakoid membranes of chloroplasts.
    • The thylakoid structure provides a large surface area for light absorption and electron transfer.
    • Match the pigment with its role in photosynthesis:
      Chlorophyll a ↔️ Primary photosynthetic pigment
      Chlorophyll b ↔️ Enhances light absorption
      Carotenoids ↔️ Light absorption and photoprotection
    • What is the first step in Photosystem II (PSII)?
      Light absorption
    • In PSII, energized electrons are passed through a series of electron carriers in the thylakoid membrane.
    • Steps involved in Photosystem II (PSII) during photosynthesis
      1️⃣ Light Absorption by pigments
      2️⃣ Excitation of Electrons
      3️⃣ Electron Transfer through carriers
      4️⃣ Water Splitting
      5️⃣ ATP Synthesis
    • What is the primary pigment in Photosystem II that absorbs light?
      Chlorophyll a
    • The absorbed light energy excites electrons, which are then transferred to the reaction center
    • Where are the electron carriers located in Photosystem II?
      Thylakoid membrane
    • Water splitting in Photosystem II releases oxygen, protons, and electrons.
    • The accumulation of protons in the thylakoid lumen creates a proton gradient
    • What is the overall equation for the light-dependent reactions initiated by PSII?
      2H_{2}O + light \rightarrow O_{2} + 4H^{ + } + 4e^{ - }</latex>
    • Match the products of the light-dependent reactions with their role:
      Oxygen ↔️ Released into the atmosphere
      Protons ↔️ Create a gradient for ATP synthesis
      Electrons ↔️ Used to generate ATP and NADPH
    • What is the role of Photosystem II (PSII) in the light-dependent reactions of photosynthesis?
      Crucial component
    • Steps involved in Photosystem II (PSII)
      1️⃣ Light Absorption
      2️⃣ Excitation of Electrons
      3️⃣ Electron Transfer
      4️⃣ Water Splitting
      5️⃣ ATP Synthesis
    • Water splitting in PSII releases oxygen, protons, and electrons
    • What is the overall equation for the light-dependent reactions initiated by PSII?
      2H_{2}O + light \rightarrow O_{2} + 4H^{ + } + 4e^{ - }</latex>
    • Photosystem I (PSI) complements PSII by regenerating NADPH for carbon fixation
    • In PSI, energized electrons are passed to ferredoxin, then to NADP+
    • What is the overall chemical equation for NADPH formation in PSI?
      2NADP++2NADP^{ + } +4H++ 4H^{ + } +4e2NADPH+ 4e^{ - } \rightarrow 2NADPH +2H+ 2H^{ + }
    • The light-dependent reactions produce oxygen, ATP, and NADPH
    • Light-dependent reactions use light energy to convert water into oxygen, ATP, and NADPH
    • Where do the light-dependent reactions occur in the chloroplast?
      Thylakoid membranes
    • Thylakoids are stacked into structures called grana, which increase the surface area for light-dependent reactions
    • The thylakoid membranes are the site of the light-dependent reactions
    • What are grana in the chloroplast composed of?
      Stacks of thylakoids
    • Match the photosynthetic pigment with its role:
      Chlorophyll a ↔️ Primary photosynthetic pigment
      Chlorophyll b ↔️ Enhances light absorption
      Carotenoids ↔️ Light absorption, photoprotection
    • Chlorophyll a absorbs blue-violet and red light most effectively
    • Chlorophyll b broadens the spectrum of light plants can utilize
    • What type of light does chlorophyll a absorb most effectively?
      Blue-violet and red
    • Chlorophyll a is the primary pigment directly participating in light reactions.
    • Chlorophyll b broadens the spectrum of light that plants can utilize
    • What is the role of carotenoids in photosynthesis?
      Protect chlorophyll from light damage