Mastering Biology: Redox Reactions
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Questions and Answers

What happens to a glucose molecule during glycolysis?

  • It is converted into ethanol and CO2.
  • It is broken down into two molecules of pyruvate. (correct)
  • It is oxidized to acetyl CoA.
  • It directly produces ATP without any other reactions.

    • Which of the following best describes oxidative phosphorylation?

  • It is the phase where ATP is synthesized through chemiosmosis. (correct)
  • It does not produce ATP but only electron carriers.
  • It occurs during glycolysis only.
  • It involves the direct transfer of a phosphate group from a substrate to ADP.

    • Which two electron carriers transfer electrons derived from glucose to the electron transport chain?

  • FADH2 and NAD+
  • NADH and ATP
  • FAD and NADP+
  • NADH and FADH2 (correct)

    • How is some ATP synthesized during cellular respiration?

    <p>Through substrate-level phosphorylation.</p> Signup and view all the answers

    In the reaction CH2O + FAD → CHO2 + FADH2, which compound is reduced?

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

    What happens to glucose during cellular respiration?

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

    Which statement describes the role of O2 in cellular respiration?

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

    What is the primary energy source produced during cellular respiration?

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

    Which type of molecules are considered good fuels for oxidation?

    <p>Molecules with multiple C-H bonds.</p> Signup and view all the answers

    What characterizes the electron transfer in respiration?

    <p>Electrons lose potential energy.</p> Signup and view all the answers

    What process does the combustion of methane exemplify?

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

    Which of the following is true regarding the transformation of energy during respiration?

    <p>Energy is released as electrons fall to a lower energy state.</p> Signup and view all the answers

    What is released as a byproduct of glucose oxidation in cellular respiration?

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

    What is the primary role of the electron transport chain in cellular respiration?

    <p>To facilitate the transfer of electrons from NADH to oxygen</p> Signup and view all the answers

    Which of the following correctly describes a consequence of uncontrolled electron transfer from hydrogen to oxygen?

    <p>It can lead to an explosion due to rapid energy release</p> Signup and view all the answers

    What happens to electrons as they move down the chain of the electron transport system?

    <p>They release energy used to pump protons across the membrane</p> Signup and view all the answers

    Which metabolic stage of cellular respiration involves the breakdown of glucose into pyruvate?

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

    What is the final electron acceptor in the electron transport chain?

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

    Which of the following statements about glycolysis is true?

    <p>It breaks down glucose into two molecules of pyruvate</p> Signup and view all the answers

    How does ATP synthesis occur in the process of chemiosmosis?

    <p>Through the potential energy of a proton gradient</p> Signup and view all the answers

    What occurs during pyruvate oxidation?

    <p>Acetyl CoA is produced</p> Signup and view all the answers

    Which of the following best describes the catabolic pathways involved in cellular respiration?

    <p>They break down molecules to release energy and produce ATP</p> Signup and view all the answers

    Which of the following is a product of the electron transport chain?

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

    What is the primary function of fermentation in cellular metabolism?

    <p>To generate a continuous supply of NAD for glycolysis</p> Signup and view all the answers

    Which process is specifically used to produce ethanol?

    <p>Alcohol fermentation</p> Signup and view all the answers

    During lactic acid fermentation, what is directly produced from pyruvate?

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

    What is a byproduct of alcohol fermentation?

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

    Which of the following organisms is known to perform alcohol fermentation?

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

    What is the main role of NAD in the process of fermentation?

    <p>To accept electrons during oxidation</p> Signup and view all the answers

    Which type of fermentation does not produce carbon dioxide as a byproduct?

    <p>Lactic acid fermentation</p> Signup and view all the answers

    Which of the following best describes where alcohol fermentation occurs?

    <p>Only in anaerobic conditions</p> Signup and view all the answers

    What happens to glucose during cellular respiration?

    <p>It is broken down in a series of enzyme-catalyzed steps.</p> Signup and view all the answers

    What is the primary final electron acceptor in fermentation?

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

    Which coenzyme acts as an electron carrier during cellular respiration?

    <p>NAD+</p> Signup and view all the answers

    What is the primary function of NAD+ in cellular respiration?

    <p>It acts as an electron acceptor.</p> Signup and view all the answers

    How much ATP is produced by fermentation per glucose molecule?

    <p>2</p> Signup and view all the answers

    Which process requires an electron transport chain to regenerate NAD+?

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

    What remains after dehydrogenases remove hydrogen atoms from glucose?

    <p>Some negative charge is neutralized.</p> Signup and view all the answers

    What characterizes an obligate anaerobe?

    <p>Can only carry out fermentation or anaerobic respiration</p> Signup and view all the answers

    How do electrons lose potential energy during cellular respiration?

    <p>They are moved along an energy gradient to O₂.</p> Signup and view all the answers

    What byproduct is formed when hydrogen reacts with oxygen in cellular respiration?

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

    Which of the following is a product of lactic acid fermentation?

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

    What is a characteristic of NAD+ as an electron acceptor?

    <p>It participates in multiple redox reactions.</p> Signup and view all the answers

    What happens to pyruvate under aerobic conditions in yeast cells?

    <p>It enters the citric acid cycle</p> Signup and view all the answers

    What is the maximum ATP yield from one molecule of glucose during aerobic respiration?

    <p>32</p> Signup and view all the answers

    Why is the explosive reaction between hydrogen and oxygen not efficient for energy production in cells?

    <p>It releases energy all at once.</p> Signup and view all the answers

    In the reaction catalyzed by dehydrogenases, what is formed alongside NADH?

    <p>Hydrogen Ion (H+)</p> Signup and view all the answers

    Which type of muscle fibers primarily uses aerobic respiration?

    <p>Red muscle fibers</p> Signup and view all the answers

    What is the significance of NADH formed during respiration?

    <p>It represents stored energy for ATP production.</p> Signup and view all the answers

    Which organism type can survive by using either fermentation or respiration?

    <p>Facultative anaerobes</p> Signup and view all the answers

    What occurs during glycolysis in all three pathways?

    <p>Oxidation of glucose to pyruvate</p> Signup and view all the answers

    Study Notes

    Redox Reactions

    • Oxidation involves the loss of electrons or hydrogen, while reduction involves the gain of electrons or hydrogen.
    • In cellular respiration: glucose (C6H12O6) is oxidized to carbon dioxide (CO2), and oxygen (O2) is reduced to water (H2O).
    • The equation for respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy represents a redox process.

    Cellular Respiration Overview

    • Cellular respiration can be divided into three stages:
      • Glycolysis: occurs in the cytosol, breaking glucose into two pyruvate molecules.
      • Pyruvate Oxidation and Citric Acid Cycle: further oxidation of pyruvate occurs in mitochondria, resulting in CO2 production.
      • Oxidative Phosphorylation: involves electron transport chains and chemiosmosis, generating ATP.

    NAD+ and Electron Transport Chain

    • Nicotinamide adenine dinucleotide (NAD+) serves as a key electron carrier, cycling between oxidized (NAD+) and reduced forms (NADH).
    • Dehydrogenase enzymes remove hydrogen atoms from glucose, oxidizing it and transferring electrons to NAD+, forming NADH.
    • NADH stores energy that can be transferred to generate ATP as electrons are passed down the electron transport chain.

    Energy Release Mechanism

    • The electron transport chain consists of proteins embedded in the mitochondrial inner membrane.
    • Electrons move down the chain, releasing energy used to pump protons, creating a proton gradient utilized for ATP synthesis.
    • This process contrasts with single-step reactions (e.g., hydrogen and oxygen explosion), enabling controlled energy release.

    Fermentation Processes

    • Fermentation regenerates NAD+ by transferring electrons from NADH to pyruvate or its derivatives, allowing glycolysis to continue.
    • Alcohol fermentation converts pyruvate to ethanol and CO2; lactic acid fermentation converts pyruvate directly to lactate, regenerating NAD+ without CO2 release.

    Comparison of ATP Production

    • Fermentation: yields 2 ATP per glucose molecule via substrate-level phosphorylation.
    • Aerobic respiration yields up to 32 ATP per glucose due to electron transport chain efficiency, maximizing energy extraction.
    • Anaerobic respiration uses another electron acceptor instead of oxygen, resulting in lower energy yield than aerobic respiration.

    Muscle Fiber Types and Lactic Acid

    • Human muscles have two fiber types: red muscle (aerobic, oxidizes glucose completely) and white muscle (produces lactate even in the presence of oxygen).
    • Lactate produced by white muscle can be oxidized by nearby red muscle or transported to the liver for glucose formation.
    • Not all lactate production is due to anaerobic conditions; it can occur even during aerobic respiration in muscle cells under certain circumstances.

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    Description

    This quiz explores the concept of redox reactions, specifically focusing on the oxidation of methane. You'll learn how oxidation and reduction processes play a crucial role in energy release during combustion and cellular respiration. Analyze the carbon atom's role in these transformations.

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