Cellular Respiration: Krebs Cycle and Glycolysis
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Questions and Answers

In what specific location within the cell does the Krebs cycle take place?

  • The mitochondrial matrix (correct)
  • The intermembrane space of the mitochondria
  • The cytoplasm
  • The inner mitochondrial membrane

    • What is the primary role of NADH and FADH2 molecules produced by the Krebs cycle?

  • To directly phosphorylate ADP into ATP
  • To serve as enzymes that catalyze metabolic reactions
  • To act as substrates in the Krebs Cycle reactions
  • To donate electrons to the electron transport chain (correct)

    • What byproduct of pyruvate breakdown is released during the Krebs cycle?

  • Oxygen
  • Lactic acid
  • Water
  • Carbon dioxide (correct)

    • How is the majority of ATP generated during aerobic respiration?

    <p>By the movement of H+ ions through ATP synthase during chemiosmosis</p> Signup and view all the answers

    What is the final destination of the electrons from NADH and FADH2 that enter the electron transport chain?

    <p>They are used to establish a H+ gradient, which powers ATP synthesis</p> Signup and view all the answers

    What is the net ATP gain from glycolysis?

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

    In which cellular location does the Krebs cycle take place?

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

    What is the primary role of NADH in cellular respiration?

    <p>To carry high-energy electrons to the ETC</p> Signup and view all the answers

    Which process uses the energy of an H+ gradient to synthesize ATP?

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

    Substrate-level phosphorylation is characterized by which of these?

    <p>It involves an enzyme transferring a phosphate group.</p> Signup and view all the answers

    What is the end product of glycolysis?

    <p>Pyruvic acid, ATP, and NADH</p> Signup and view all the answers

    How many ATP molecules are initially invested in the process of glycolysis?

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

    What percentage of the total chemical energy available in a glucose molecule remains unused after glycolysis?

    <p>90%</p> Signup and view all the answers

    What is the primary purpose of fermentation in cells?

    <p>To regenerate NAD+ for glycolysis.</p> Signup and view all the answers

    Which molecule is produced during lactic acid fermentation?

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

    Where does glycolysis occur in the cell?

    <p>In the cytoplasm</p> Signup and view all the answers

    What is one of the end products of alcoholic fermentation?

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

    Under what condition does lactic acid build up in muscles?

    <p>During intense exercise when oxygen is limited</p> Signup and view all the answers

    Substrate-level phosphorylation is a method of producing ATP. What is required for substrate-level phosphorylation?

    <p>An enzyme</p> Signup and view all the answers

    Which of following processes would NOT occur in an anaerobic respiration pathway?

    <p>Krebs Cycle</p> Signup and view all the answers

    How many net ATP molecules are produced per glucose molecule during fermentation?

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

    Where does the electron transport chain occur?

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

    What is the net gain of ATP molecules during glycolysis?

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

    Which molecule is the final product of glycolysis and proceeds to the Krebs cycle?

    <p>Pyruvic acid</p> Signup and view all the answers

    What is the primary function of NADH and FADH2 in cellular respiration?

    <p>Act as electron carriers</p> Signup and view all the answers

    In which part of the mitochondria does the Krebs cycle take place?

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

    What is the role of ATP synthase in the electron transport chain?

    <p>To convert H+ gradient into ATP</p> Signup and view all the answers

    Besides ATP what is another product of glycolysis, that then moves to the Electron transport chain?

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

    What is a byproduct of pyruvate breakdown in the Krebs cycle?

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

    During strenuous exercise, why does lactic acid build up in muscles?

    <p>Because oxygen cannot be delivered quickly enough</p> Signup and view all the answers

    Which of the following correctly describes the relationship between cellular respiration and fermentation?

    <p>Fermentation is an anaerobic alternative mechanism for cells to create ATP when aerobic respiration is limited</p> Signup and view all the answers

    What is the end product of alcoholic fermentation in addition to carbon dioxide?

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

    Where in the cell does lactic acid fermentation take place?

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

    What is the primary role of oxygen in the electron transport chain (ETC)?

    <p>To act as the final electron acceptor, forming water</p> Signup and view all the answers

    What is the net ATP production per glucose molecule through cellular respiration?

    <p>38 ATP</p> Signup and view all the answers

    What is the function of the electron shuttle in cellular respiration?

    <p>To move NADH electrons from glycolysis into the mitochondria</p> Signup and view all the answers

    Which of the following best describes fermentation?

    <p>An anaerobic process that produces small amounts of ATP and regenerates NAD+</p> Signup and view all the answers

    What is the consequence of running out of NAD+ during glycolysis?

    <p>Glycolysis will stop because electron carriers are full</p> Signup and view all the answers

    What is the function of converting NADH to NAD+ during fermentation?

    <p>To ensure that glycolysis can continue by replenishing electron carriers</p> Signup and view all the answers

    How do cells transfer high-energy electrons from NADH and FADH2 to ultimately produce water?

    <p>Through a series of protein transfers in the electron transport chain</p> Signup and view all the answers

    What happens to pyruvic acid during fermentation?

    <p>It is used to regenerate NAD+ by accepting electrons</p> Signup and view all the answers

    Study Notes

    Cellular Respiration

    • Cellular respiration is the aerobic process of harvesting energy from glucose to produce ATP.
    • Nearly all cells in the body break down sugars to create ATP for energy.
    • Glucose + Oxygen → Carbon Dioxide + Water + ATP (Energy)
    • 38 ATP molecules are produced per glucose molecule.
    • Cellular Respiration is a redox reaction; glucose is oxidized to carbon dioxide and oxygen is reduced to water.

    What is ATP?

    • ATP is adenosine triphosphate.
    • It's the currency of biological energy.
    • Energy is stored in the high-energy phosphate bonds.
    • When ATP is hydrolyzed (broken down), it releases energy for cellular work.
    • When ATP is created, energy is stored.

    How can we generate ATP?

    • Two methods: Chemiosmosis and substrate-level phosphorylation.
    • Chemiosmosis: ATP synthase uses the energy in the H+ ion concentration gradient across membranes to create ATP. This happens in the membranes.
    • Substrate-level phosphorylation: An enzyme transfers a phosphate group from a substrate to ADP to make ATP. This happens outside of membranes.

    Stages of Cellular Respiration

    • Glycolysis: Occurs in the cytoplasm of the cell and breaks down glucose into two molecules of pyruvic acid. A net gain of 2 ATP is created per glucose molecule. NADH is also produced.
    • Krebs Cycle (Citric Acid Cycle): Occurs in the mitochondrial matrix. Pyruvic acid is oxidized further releasing CO₂, NADH, and FADH₂. Several ATP molecules are made.
    • Electron Transport Chain (ETC): Occurs in the inner mitochondrial membrane. Electron carriers (NADH and FADH₂) release their electrons. Energy is released and used to pump H+ ions across the membrane creating a gradient. ATP synthase uses this gradient to produce a large amount of ATP. Oxygen is the final electron acceptor.

    Fermentation

    • Fermentation is an anaerobic process that occurs when oxygen is unavailable.
    • It allows glycolysis to continue by regenerating NAD+ by transferring electrons to pyruvic acid.
    • Fermentation produces small amounts of ATP (2 per glucose).
    • Two types: Alcoholic Fermentation and Lactic Acid Fermentation

    Alcoholic Fermentation

    • Pyruvic acid is converted into carbon dioxide and ethanol.
    • This process regenerates NAD+ for glycolysis to continue.

    Lactic Acid Fermentation

    • Pyruvic acid is converted into lactic acid.
    • This regenerates NAD+ for glycolysis and produces lactic acid as a byproduct (leading to muscle pain).

    Aerobic vs. Anaerobic Respiration

    • Aerobic respiration requires oxygen, and anaerobic does not.
    • Aerobic respiration is much more efficient, producing many more ATP molecules per glucose.
    • Anaerobic respiration only occurs in the cytoplasm, and aerobic also occurs in the mitochondria.

    Mitochondria: Site of Aerobic Respiration

    • Mitochondria are the site of aerobic cellular respiration in eukaryotic cells. They are the "powerhouses" producing the majority of ATP needed for cellular work.
    • The major components are the outer membrane, inner membrane, matrix, and cristae.

    Photosynthesis vs. Cellular Respiration

    • Photosynthesis and Cellular Respiration work together in the carbon cycle.
    • Photosynthesis takes carbon dioxide from the atmosphere and creates glucose.
    • Cellular respiration takes glucose and releases carbon dioxide into the atmosphere.

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    Cell Respiration Honors 2025 Student Version PDF

    Description

    Test your knowledge on the Krebs cycle and glycolysis with this quiz. Explore the specific locations within the cell, the roles of NADH and FADH2, and the processes involved in ATP generation. Delve into cellular respiration and its key components to understand how energy is produced within cells.

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