Cellular Respiration and Electron Transfer Quiz
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Questions and Answers

During which stage of cellular respiration is pyruvate oxidized?

  • Glycolysis
  • Oxidative phosphorylation
  • Fermentation
  • Citric acid cycle (correct)

    • In which process are electrons transported to ATP synthesis through chemiosmosis?

  • Citric acid cycle
  • Oxidative phosphorylation (correct)
  • Glycolysis
  • Fermentation

    • Which molecule is the primary product of glycolysis?

  • Pyruvate (correct)
  • ATP
  • NADH
  • Glucose

    • What is the main purpose of fermentation in cellular respiration?

    <p>To generate ATP without oxygen</p> Signup and view all the answers

    In a redox reaction, which substance is oxidized?

    <p>The substance losing electrons</p> Signup and view all the answers

    What is the role of O2 in cellular respiration?

    <p>O2 is reduced</p> Signup and view all the answers

    What makes O2 a powerful oxidizing agent?

    <p>Its high electronegativity</p> Signup and view all the answers

    What type of bonds in organic molecules are a source of energy?

    <p>C ¬ H bonds</p> Signup and view all the answers

    What is the function of activation energy in cellular respiration?

    <p>Acts as a barrier preventing instantaneous combination of glucose with O2</p> Signup and view all the answers

    What do carbohydrates and fats serve as in cellular respiration?

    <p>Reservoirs of electrons associated with hydrogen</p> Signup and view all the answers

    What is the main purpose of stepwise energy harvest in cellular respiration?

    <p>Efficiently harness energy for constructive work</p> Signup and view all the answers

    What is the reducing agent in a redox reaction?

    <p>Electron donor</p> Signup and view all the answers

    What is the electron acceptor in a redox reaction?

    <p>Oxidizing agent</p> Signup and view all the answers

    What is the role of oxygen in methane combustion?

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

    What happens in redox reactions that do not involve the complete transfer of electrons?

    <p>Change in the degree of electron sharing in covalent bonds</p> Signup and view all the answers

    What is the source of energy liberated from the oxidation of glucose in respiration?

    <p>Transfer of electrons to a lower energy state</p> Signup and view all the answers

    Where does glycolysis occur?

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

    What is the final product of glycolysis?

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

    Where does oxidative phosphorylation occur in eukaryotic cells?

    <p>Inner membrane of the mitochondrion</p> Signup and view all the answers

    What is the main function of the citric acid cycle?

    <p>Complete the breakdown of glucose to carbon dioxide</p> Signup and view all the answers

    What is the role of NADH and FADH2 in cellular respiration?

    <p>Transfer electrons to the electron transport chain</p> Signup and view all the answers

    Where is the energy released during cellular respiration stored?

    <p>In the form of ATP</p> Signup and view all the answers

    What is the primary function of substrate-level phosphorylation?

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

    How is oxidative phosphorylation different from substrate-level phosphorylation?

    <p>Involves the transfer of electrons to the electron transport chain</p> Signup and view all the answers

    Which stage of cellular respiration accounts for almost 90% of the ATP generated?

    <p>Oxidative phosphorylation</p> Signup and view all the answers

    What is the cumulative function of the three metabolic stages of cellular respiration?

    <p>The entire process of breaking down glucose and other organic fuels, releasing energy in the form of ATP, heat, and light</p> Signup and view all the answers

    What is the term usually reserved by biochemists for stages 2 and 3 of cellular respiration?

    <p>Cellular respiration</p> Signup and view all the answers

    What is the source of energy harvested during cellular respiration?

    <p>Organic fuels such as glucose</p> Signup and view all the answers

    Which process ultimately provides the energy stored in organic molecules of food?

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

    What are the waste products generated by cellular respiration?

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

    Which compounds can act as fuels for exergonic reactions?

    <p>Compounds that can participate in exergonic reactions</p> Signup and view all the answers

    What is the most efficient catabolic pathway that requires oxygen as a reactant?

    <p>Aerobic respiration</p> Signup and view all the answers

    Which process is a partial degradation of sugars or organic fuel that occurs without the use of oxygen?

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

    What is the free energy change per mole of glucose decomposed in the breakdown of glucose in cellular respiration?

    <p>$-686$ kcal</p> Signup and view all the answers

    What is essential for cellular function and is generated by catabolic pathways?

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

    What plays a major role in releasing stored energy in catabolic pathways?

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

    Which molecules from food can be processed and consumed as fuel for cellular respiration?

    <p>Carbohydrates, fats, and proteins</p> Signup and view all the answers

    What is the process that breaks down organic fuel using oxygen and generates ATP?

    <p>Cellular respiration</p> Signup and view all the answers

    What type of respiration refers to the process similar to the combustion of gasoline in an automobile engine?

    <p>Aerobic respiration</p> Signup and view all the answers

    What ultimately uses the energy stored in organic molecules of food to synthesize ATP through redox reactions?

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

    What happens to NAD+ during cellular respiration?

    <p>It is reduced to NADH by receiving 2 electrons and 1 proton from the substrate.</p> Signup and view all the answers

    What is the function of NADH in cellular respiration?

    <p>It represents stored energy that can be tapped to make ATP when the electrons complete their “fall” down an energy gradient from NADH to O2.</p> Signup and view all the answers

    Where does the electron transport chain primarily exist in the cell?

    <p>Inner membrane of mitochondria</p> Signup and view all the answers

    What is the role of O2 in cellular respiration?

    <p>It captures electrons along with hydrogen nuclei at the bottom of the electron transport chain, forming water.</p> Signup and view all the answers

    What is the main function of the electron transport chain during cellular respiration?

    <p>To facilitate the transfer of electrons from NADH to O2, generating ATP.</p> Signup and view all the answers

    What represents the stored energy that can be tapped to make ATP during cellular respiration?

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

    What happens to NADH during cellular respiration?

    <p>It donates electrons to the electron transport chain, generating ATP.</p> Signup and view all the answers

    Where do most electrons travel during cellular respiration?

    <p>Glucose → NADH → electron transport chain → oxygen</p> Signup and view all the answers

    What is the role of dehydrogenases in cellular respiration?

    <p>To remove a pair of hydrogen atoms from the substrate, oxidizing it and forming NADH.</p> Signup and view all the answers

    Study Notes

    Cellular Respiration and Electron Transfer

    • Glucose is broken down in a series of steps, catalyzed by enzymes, with electrons being stripped at key steps.
    • Hydrogen atoms from glucose are usually passed first to an electron carrier, NAD+, which can cycle between its oxidized and reduced forms.
    • Dehydrogenases remove a pair of hydrogen atoms from the substrate, oxidizing it and forming NADH.
    • NAD+ is reduced to NADH by receiving 2 electrons and 1 proton from the substrate.
    • NADH represents stored energy that can be tapped to make ATP when the electrons complete their “fall” down an energy gradient from NADH to O2.
    • Cellular respiration brings hydrogen and oxygen together to form water through an electron transport chain, consisting of mostly proteins, built into the inner membrane of mitochondria.
    • Electrons removed from glucose are shuttled by NADH to the top of the chain, and at the bottom, O2 captures these electrons along with hydrogen nuclei, forming water.
    • Electron transfer from NADH to oxygen is an exergonic reaction, with electrons cascading down the chain from one carrier molecule to the next in a series of redox reactions.
    • O2 pulls electrons down the chain in an energy-yielding tumble analogous to gravity pulling objects downhill.
    • Most electrons travel the following “downhill” route during cellular respiration: glucose → NADH → electron transport chain → oxygen.
    • The cell uses the energy released from this exergonic electron fall to regenerate its supply of ATP.
    • NAD+ is the most versatile electron acceptor in cellular respiration and functions in several of the redox steps during the breakdown of glucose.

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    Description

    Test your knowledge of cellular respiration and electron transfer with this quiz. Explore the steps of glucose breakdown, electron transfer, and ATP production in cellular respiration.

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