Photosynthesis and Light Reactions Quiz
45 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Photosystem I directly facilitates which process?

  • The transport of hydrogen ions into the thylakoid lumen.
  • The reduction of water to release oxygen.
  • The synthesis of plastoquinol from plastocyanin.
  • The transfer of electrons across the thylakoid membrane. (correct)

    • What is the primary function of plastocyanin?

  • To accept electrons from water and initiate the electron transport chain.
  • To directly catalyze the synthesis of ATP through chemiosmosis.
  • To act as an electron carrier in the electron transport process. (correct)
  • To convert light energy into chemical energy within the photosystems.

    • Which of the following describes the role of plastoquinol in photosynthesis?

  • It acts as an electron and energy carrier in the electron transport chain. (correct)
  • It serves as the primary light-capturing pigment in photosystem II.
  • It mediates electron transfer by accepting electrons from plastocyanin.
  • It is directly responsible for the splitting of water molecules.

    • What is the nature of photosystem I as described in the text?

    <p>An integral membrane protein complex. (B)</p> Signup and view all the answers

    The light reactions of photosynthesis are powered by what?

    <p>Light energy. (A)</p> Signup and view all the answers

    Where does the light-dependent reaction primarily take place within the chloroplast?

    <p>Thylakoid membrane (C)</p> Signup and view all the answers

    Which of the following best describes the role of chlorophyll in the light-dependent reactions?

    <p>It captures light energy to excite electrons. (D)</p> Signup and view all the answers

    What are the direct energy-containing products generated during the light-dependent reactions?

    <p>ATP and NADPH (D)</p> Signup and view all the answers

    What is the primary function of photosynthesis?

    <p>To transform sunlight into chemical energy stored in organic molecules (A)</p> Signup and view all the answers

    What is the ultimate source of electrons that replenish the reaction center of Photosystem II?

    <p>Water (D)</p> Signup and view all the answers

    According to the text which of these is an autotroph?

    <p>Mosses, ferns, and flowering plants (D)</p> Signup and view all the answers

    Which protein complex has P700 as its reaction center?

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

    Why is photosynthesis considered essential for life on Earth?

    <p>It forms the base of all food chains and produces oxygen. (C)</p> Signup and view all the answers

    The oxygen produced during photosynthesis originates from which molecule?

    <p>Water (D)</p> Signup and view all the answers

    What enables plants to appear green?

    <p>The reflection of green wavelengths of visible light by chloroplasts. (C)</p> Signup and view all the answers

    What is the primary function of the electron transport chain in the light-dependent reactions?

    <p>To generate a proton gradient and synthesize ATP (D)</p> Signup and view all the answers

    Which inorganic materials are used in photosynthesis to create organic molecules?

    <p>Carbon dioxide and water (D)</p> Signup and view all the answers

    What is the correct sequence of electron flow between the two photosystems during light-dependent reactions?

    <p>Photosystem II → Electron Transport Chain → Photosystem I (B)</p> Signup and view all the answers

    What are the “special pairs” mentioned in the context of why plants are green?

    <p>Chlorophyll molecules (A)</p> Signup and view all the answers

    Besides plants, which of the following organisms also perform photosynthesis?

    <p>Some bacteria and protists. (A)</p> Signup and view all the answers

    What would happen to the levels of oxygen if photosynthesis suddenly ended on earth?

    <p>Oxygen levels would decline dramatically. (D)</p> Signup and view all the answers

    What is the ultimate source of electrons that replenish Photosystem II?

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

    In oxygenic photosynthesis, what substance is produced as a direct result of Photosystem II’s activity?

    <p>Oxygen gas (B)</p> Signup and view all the answers

    Which of the following is a role of Photosystem II in the light-dependent reactions?

    <p>Splits water to replace lost electrons (D)</p> Signup and view all the answers

    Where is Photosystem II primarily located within plant cells?

    <p>In the thylakoid membrane (A)</p> Signup and view all the answers

    Which of these substances acts as an electron acceptor associated directly with Photosystem II?

    <p>Plastoquinone (A)</p> Signup and view all the answers

    Besides providing electrons, what does the energy captured by Photosystem II contribute to?

    <p>Pumping of hydrogen ions across the membrane (A)</p> Signup and view all the answers

    In which specific process is the energy extracted from water molecules used by Photosystem II?

    <p>To generate electrons (A)</p> Signup and view all the answers

    What is a key function of the electron flow facilitated by Photosystem II?

    <p>Providing the power for ATP synthesis (C)</p> Signup and view all the answers

    What is the primary role of RuBisCO in the Calvin cycle?

    <p>To catalyze the reaction between CO2 and RuBP. (C)</p> Signup and view all the answers

    Why is the conversion of 3-PGA to G3P considered a reduction reaction?

    <p>Because it involves the gain of electrons by the 3-PGA molecule. (D)</p> Signup and view all the answers

    What is the immediate product formed after CO2 is added to RuBP?

    <p>An unstable six-carbon compound. (C)</p> Signup and view all the answers

    What is the significance of the three-carbon molecule in C3 plants?

    <p>It refers to the first stable carbon compound produced during photosynthesis. (C)</p> Signup and view all the answers

    Which of the following conversions happens during the ‘reduction’ stage of the Calvin cycle?

    <p>Conversion of 3-PGA to G3P. (C)</p> Signup and view all the answers

    What molecule provides the carbon atoms that ends up in glucose?

    <p>CO2. (D)</p> Signup and view all the answers

    What is the role of ATP and NADPH in the Calvin cycle?

    <p>They provide the energy to convert 3-PGA to G3P. (A)</p> Signup and view all the answers

    Where does the carbon fixation in the Calvin cycle take place within the chloroplast?

    <p>Stroma. (A)</p> Signup and view all the answers

    What is the immediate product derived from PGA in the Calvin cycle?

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

    How many turns of the Calvin cycle are required to produce one molecule of glucose?

    <p>6 (D)</p> Signup and view all the answers

    Which molecule is regenerated using G3P in the Calvin cycle?

    <p>RuBP (B)</p> Signup and view all the answers

    Besides carbon dioxide, what other molecule is an input in the Calvin cycle?

    <p>ATP (C)</p> Signup and view all the answers

    What happens to the rate of photosynthesis as the temperature is increased, up to a certain limit?

    <p>The rate increases (D)</p> Signup and view all the answers

    What are the products of photorespiration?

    <p>2-Carbon molecules, no sugar or ATP (A)</p> Signup and view all the answers

    What is the role of Rubisco in the Calvin Cycle?

    <p>It fixes carbon dioxide into a carbohydrate (D)</p> Signup and view all the answers

    What is the main distinction between C4 and CAM plants related to their environment?

    <p>C4 plants live in hot, moist environments, while CAM plants can live in dry conditions. (D)</p> Signup and view all the answers

    Flashcards

    Autotroph

    Organisms that can produce their own food from inorganic sources, like sunlight.

    Photosynthesis

    The process of converting light energy into chemical energy (sugars) using carbon dioxide and water.

    Chlorophyll

    The main pigment in plants that absorbs light energy for photosynthesis, reflecting green light.

    Photosynthesis

    The process by which organisms convert light energy into chemical energy.

    Signup and view all the flashcards

    Glucose

    The fundamental building block of life, produced by photosynthesis.

    Signup and view all the flashcards

    Oxygen

    A gas essential for respiration, released as a byproduct of photosynthesis.

    Signup and view all the flashcards

    Carbon dioxide

    A colorless gas used by plants during photosynthesis.

    Signup and view all the flashcards

    Respiration

    The process by which organisms break down glucose to release energy.

    Signup and view all the flashcards

    Photosystem I

    A protein complex in thylakoid membranes that uses light energy to energize electrons and transfer them across the membrane during photosynthesis.

    Signup and view all the flashcards

    Photosystem II

    A protein complex in thylakoid membranes that absorbs light energy to split water molecules, releasing oxygen and generating electrons for the electron transport chain.

    Signup and view all the flashcards

    Plastoquinone

    A mobile electron carrier that transfers energized electrons from Photosystem II to Photosystem I in the electron transport chain.

    Signup and view all the flashcards

    Plastocyanin

    A protein complex that carries energized electrons from Photosystem I to NADP reductase, where NADPH is produced during photosynthesis.

    Signup and view all the flashcards

    Chemiosmosis

    The process by which ATP is generated in the chloroplasts during photosynthesis, using the energy stored in the proton gradient created by the electron transport chain.

    Signup and view all the flashcards

    Water Splitting

    The process where Photosystem II regains electrons by splitting water molecules, releasing oxygen as a byproduct.

    Signup and view all the flashcards

    Light Energy Capture

    The key process in Photosystem II where light energy is captured and used to extract electrons from water molecules.

    Signup and view all the flashcards

    Electron Flow

    In Photosystem II, the electrons flow down the chain and are used to pump hydrogen ions across the thylakoid membrane, providing energy for ATP synthesis.

    Signup and view all the flashcards

    Proton Pumping

    The process in Photosystem II where electrons flow down a chain and pump hydrogen ions across the membrane, powering ATP synthesis.

    Signup and view all the flashcards

    Proton Gradient

    The movement of hydrogen ions across the thylakoid membrane due to the electron flow, creating a gradient used to generate ATP.

    Signup and view all the flashcards

    Light-Dependent Reaction

    The first stage of photosynthesis, where light energy is captured and converted into chemical energy in the form of ATP and NADPH.

    Signup and view all the flashcards

    NADPH

    An electron carrier molecule that carries high-energy electrons from the light reaction to the Calvin cycle.

    Signup and view all the flashcards

    ATP

    A molecule that serves as the primary energy currency of cells, produced during the light reaction.

    Signup and view all the flashcards

    Electron Transport Chain

    A series of proteins embedded in the thylakoid membrane that pass electrons down a chain, releasing energy for ATP production.

    Signup and view all the flashcards

    Photosystem II (PS II)

    A specialized complex in the thylakoid membrane that captures light energy and uses it to split water molecules.

    Signup and view all the flashcards

    Photosystem I (PS I)

    A specialized complex in the thylakoid membrane that captures light energy and uses it to energize electrons and produce NADPH.

    Signup and view all the flashcards

    NADPH

    The energy-rich molecule that is produced by the light reaction and used in the Calvin cycle to build sugars.

    Signup and view all the flashcards

    Carbon Fixation

    The first step in the Calvin cycle where carbon dioxide is incorporated into an organic molecule, specifically RuBP, a five-carbon sugar, catalyzed by the enzyme RuBisCO.

    Signup and view all the flashcards

    RuBP (Ribulose bisphosphate)

    A five-carbon sugar that combines with CO2 during carbon fixation in the Calvin cycle.

    Signup and view all the flashcards

    RuBisCO

    The enzyme that catalyzes the reaction between CO2 and RuBP, initiating carbon fixation in the Calvin cycle.

    Signup and view all the flashcards

    3-PGA (3-phosphoglyceric acid)

    A three-carbon compound formed immediately after carbon fixation in the Calvin cycle, where CO2 is incorporated into RuBP, a five-carbon sugar.

    Signup and view all the flashcards

    G3P (Glyceraldehyde 3-phosphate)

    A three-carbon compound that is a key product of the Calvin cycle and a starting point for glucose synthesis in plants.

    Signup and view all the flashcards

    Reduction in Calvin Cycle

    The second step in the Calvin cycle where 3-PGA is converted into G3P using energy from ATP and NADPH.

    Signup and view all the flashcards

    Regeneration in Calvin Cycle

    The third step of the Calvin cycle where RuBP is regenerated, the starting compound of the cycle.

    Signup and view all the flashcards

    Calvin Cycle

    The cyclic series of reactions that occur in the stroma of chloroplasts during photosynthesis, where carbon dioxide is converted into glucose.

    Signup and view all the flashcards

    Glyceraldehyde 3-phosphate (G3P)

    The 3-carbon sugar produced during the Calvin cycle.

    Signup and view all the flashcards

    Photorespiration

    The process that takes place in plants when oxygen is fixed instead of carbon dioxide by the enzyme Rubisco.

    Signup and view all the flashcards

    C4 Photosynthesis

    A carbon fixation pathway found in some plants that allows them to thrive in hot climates.

    Signup and view all the flashcards

    CAM Plants

    A group of plants that use a special adaptation to minimize photorespiration, primarily found in arid environments.

    Signup and view all the flashcards

    RuBP Regeneration

    The process by which the Calvin cycle regenerates its starting material, RuBP.

    Signup and view all the flashcards

    Study Notes

    Photosynthesis: Chapter 4

    • Photosynthesis is the process where plants and certain other organisms create their own food using sunlight, carbon dioxide, and water.
    • Plants are photosynthetic autotrophs, along with some bacteria and protists.
    • Sunlight is transformed into chemical energy stored in bonds (glucose) from inorganic matter (carbon dioxide).
    • The process produces glucose (a type of sugar) and oxygen as a byproduct.

    Importance of Photosynthesis

    • Photosynthesis generates organic molecules (glucose) from inorganic materials (carbon dioxide and water).
    • It is foundational to all food chains.
    • It produces oxygen.
    • Photosynthesis is vital for oxygen on Earth.

    Why Are Plants Green?

    • Plants appear green because they reflect green light.
    • Plants absorb other colors of light (red, blue) most efficiently, leaving green light to be reflected.
    • Chlorophyll, a green pigment, is involved in capturing light energy for photosynthesis.

    Chloroplasts: Sites of Photosynthesis

    • Chloroplasts are organelles in plant cells where photosynthesis occurs.
    • Chlorophyll is the main pigment, absorbing most light wavelengths except green (which is reflected).
    • Chloroplasts contain multiple pigments aiding light absorption.
    • Chloroplasts contain several pigments, including chlorophyll a, chlorophyll b, and carotenoids.

    Photosynthesis Process Overview

    • Photosynthesis involves two main stages: light-dependent reactions and the Calvin cycle.
    • Light Reactions:
      • Capture light energy to produce ATP and NADPH, along with the release of oxygen.
      • Water is used, and oxygen is released as a byproduct.
    • Calvin cycle:
      • Uses ATP and NADPH (products of light reactions) to convert carbon dioxide into glucose (sugar).
    • The combination of light and dark reactions results in production of glucose from CO2 and water.

    The Color of Light Seen

    • The color of light reflected is the color seen.
    • Chlorophyll absorbs light energy, converting it to chemical energy.
    • Pigments absorb different colors of light, with chlorophyll absorbing all wavelengths except green.

    Photosynthesis in Chloroplasts

    • Chloroplasts are the organelles for photosynthesis, located primarily in leaves.
    • Chloroplasts contain stroma (a fluid), grana (stacks of thylakoids), and thylakoids (where light-dependent reactions take place).
    • Chlorophyll is contained in the thylakoid membranes.

    Oxidation and Reduction

    • Oxidation is the loss of electrons (gain of oxygen)
    • Reduction is the gain of electrons (loss of oxygen)
    • These are key processes in the transfer of energy related to photosynthesis.

    Chemiosmosis

    • Chemiosmosis in photosynthesis: the process of creating a hydrogen ion (H+) gradient to generate ATP.
    • The light-dependent reactions generate a H+ gradient across the thylakoid membrane.
    • ATP synthase is involved in creating ATP as H+ ions move back to the stroma.

    Dark Reactions in the Calvin Cycle

    • Carbon Fixation: Carbon from CO2 combines with ribulose bisphosphate (RuBP)
    • Reduction: 3-PGA (a 3-carbon molecule) is converted to G3P (another 3-carbon molecule), involving ATP and NADPH.
    • Regeneration: G3P is used to regenerate RuBP, enabling the continuation of the cycle.
    • Requires ATP and NADPH from light reactions.
    • Creates glucose from carbon dioxide.

    Factors Affecting Photosynthesis

    • Light intensity: Higher light, higher rate of photosynthesis.
    • Temperature: Moderate temperatures are best, high temperatures can slow or stop photosynthesis.
    • Carbon dioxide concentration: Higher CO2 levels result in higher photosynthetic rates.
    • Water Availability: Water is needed to fuel the reaction.

    Photorespiration

    • Occurs in hot and dry conditions when plants close their stomata to conserve water.
    • Results in the release of CO2 and the use of ATP without producing sugars.
    • Photorespiration is not efficient for photosynthesis.

    C4 Plants

    • Adaptations to minimize photorespiration in hot, dry climates.
    • Spatial separation of light and dark reactions in different cell types (mesophyll and bundle-sheath cells).
    • PEP carboxylase initially fixes CO2 into a 4-carbon molecule, concentrating CO2 for more efficient capture.

    CAM Plants

    • Adaptations to minimize photorespiration in very hot, dry climates.
    • Temporal separation of light and dark reactions, opening stomata at night to take up CO2.
    • Storing CO2 during the night as a4-carbon molecule, releasing it during the day for photosynthesis.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Photosynthesis - Session 4 PDF

    Description

    Test your knowledge on the light-dependent reactions of photosynthesis. This quiz covers key concepts such as the roles of photosystems, chlorophyll, and essential molecules like plastocyanin and plastoquinol. Dive into the fascinating processes that sustain life on Earth.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser