Plant Physiology Unit 4 Quiz
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Questions and Answers

What is the primary role of the splitting of water in photosynthesis?

  • To form carbon dioxide for the process
  • To provide electrons for photosystem II (correct)
  • To release glucose as a byproduct
  • To create ATP directly
  • During which type of photo-phosphorylation do both photosystems operate in a sequence?

  • Light-dependent photo-phosphorylation
  • Non-cyclic photo-phosphorylation (correct)
  • Cyclic photo-phosphorylation
  • Thermodynamic photo-phosphorylation
  • What are the products formed from the splitting of water during photosynthesis?

  • O2, protons, and electrons (correct)
  • H2O and glucose
  • ATP and NADPH
  • Carbon dioxide and H2O
  • Where are protons and O2 likely released after water is split during photosynthesis?

    <p>Into the thylakoid lumen</p> Signup and view all the answers

    What molecule carries energy in its chemical bonds, synthesized through photo-phosphorylation?

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

    What is the role of the proton gradient across the thylakoid membrane?

    <p>It provides energy for ATP synthesis.</p> Signup and view all the answers

    Which structure of ATP synthase is responsible for the transmembrane channel facilitating the movement of protons?

    <p>CF0</p> Signup and view all the answers

    How does the breakdown of the proton gradient contribute to ATP synthesis?

    <p>It causes a conformational change in ATP synthase.</p> Signup and view all the answers

    What is necessary for the process of chemiosmosis in the chloroplasts?

    <p>A membrane, a proton pump, and ATP synthase.</p> Signup and view all the answers

    What happens to protons in the stroma during the reduction of NADP+ to NADPH?

    <p>They decrease in number.</p> Signup and view all the answers

    What is the primary consequence of water stress on a plant's leaves?

    <p>Wilting and decreased surface area</p> Signup and view all the answers

    Which is NOT a stage of photosynthesis?

    <p>Respiration process</p> Signup and view all the answers

    Which component of the chloroplast absorbs light during the light reaction?

    <p>Reaction centre chlorophylls</p> Signup and view all the answers

    How does stomatal closure due to water stress affect photosynthesis?

    <p>Reduces the availability of CO2</p> Signup and view all the answers

    What is the role of the proton gradient in photosynthesis?

    <p>To drive ATP synthesis</p> Signup and view all the answers

    What anatomical feature is characteristic of C4 plants?

    <p>Kranz anatomy</p> Signup and view all the answers

    Which enzyme is primarily responsible for CO2 fixation in C4 plants?

    <p>PEP carboxylase</p> Signup and view all the answers

    C4 plants are known to have higher productivity due to their ability to:

    <p>Fix carbon at higher temperatures</p> Signup and view all the answers

    What is the primary CO2 acceptor in the Hatch and Slack pathway?

    <p>Phosphoenol pyruvate (PEP)</p> Signup and view all the answers

    Which of the following statements correctly describes bundle sheath cells in C4 plants?

    <p>They are characterized by thick walls impervious to gas exchange.</p> Signup and view all the answers

    What does the term 'Kranz' mean in relation to C4 plant anatomy?

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

    Which type of plant is more likely to show a response to high light intensities?

    <p>C4 plants</p> Signup and view all the answers

    What is one key difference between mesophyll cells of C3 and C4 plants?

    <p>C4 mesophyll cells predominantly lack RuBisCO.</p> Signup and view all the answers

    Study Notes

    Overview of Plant Physiology

    • The study of plant physiology includes processes such as photosynthesis, respiration, and plant growth and development.
    • Perspectives on biology encompass organismic-level and molecular-level organizations, leading to fields like ecology, physiology, and biochemistry.

    Melvin Calvin and Photosynthesis

    • Melvin Calvin, born in April 1911 in Minnesota, earned a Ph.D. in Chemistry and became a professor at UC Berkeley.
    • He utilized radioactivity beneficially post-World War II, contributing to the field of photosynthesis research.

    Water Splitting in Photosynthesis

    • Water is split in photosystem II (PS II) generating protons (H+), oxygen (O2), and electrons (e-).
    • Reaction equation: 2H2O → 4H+ + O2 + 4e−.
    • Electrons from PS II replace those lost from photosystem I (PS I).

    Photo-phosphorylation Types

    • Non-cyclic Photo-phosphorylation: Involves both PS II and PS I, where ATP and NADPH are synthesized using light energy.
    • Protons are reduced from the stroma, while a proton gradient forms across the thylakoid membrane.

    Chemiosmosis and ATP Synthase

    • Chemiosmosis occurs in thylakoids, involving ATP synthesis via a proton gradient.
    • ATP synthase has two parts: CF0 embedded in the thylakoid membrane and CF1 located in the stroma, which catalyzes ATP formation as protons diffuse back through.

    C4 Plant Anatomy and Adaptations

    • C4 plants display unique leaf anatomy known as Kranz anatomy, consisting of bundle sheath cells with abundant chloroplasts.
    • Adapted to higher temperatures and intense light, they avoid photorespiration, resulting in increased biomass production.

    Hatch and Slack Pathway

    • The primary CO2 acceptor in the Hatch and Slack pathway is phosphoenol pyruvate (PEP), without RuBisCO enzyme in mesophyll cells.
    • This cyclic process is essential for C4 photosynthesis, enhancing efficiency in tropical climates.

    Influence of Water on Photosynthesis

    • Water stress can close stomata, reducing CO2 availability and causing leaf wilting, thus impacting metabolic activity and photosynthesis efficiency.

    Summary of Photosynthesis

    • Photosynthesis in green plants converts CO2 into carbohydrates like glucose and starch, primarily occurring in mesophyll cells of leaves.
    • The process consists of two main stages: light reactions and carbon-fixing reactions, where chlorophylls capture light energy to produce NADH and create a proton gradient.

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    Description

    Test your knowledge on Chapter 11 and Chapter 12 of Plant Physiology, focusing on photosynthesis in higher plants. This quiz explores the structure and variation of living organisms, delving into the two perspectives on biology. Challenge yourself with questions that assess your understanding of these key concepts.

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