Cellular Respiration Overview
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Questions and Answers

What is the primary respiratory substrate used in cellular respiration?

  • Organic acids
  • Fats
  • Carbohydrates (correct)
  • Proteins

    • All the energy from respiratory substrates is released at once during cellular respiration.

    False

    What acts as the energy currency of the cell?

    ATP

    The sequence of use of respiratory substrates is carbohydrates, _____, and proteins.

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

    Match the following respiratory substrates with their calorific values:

    <p>Carbohydrate = 4.1 kcal/g Protein = 5.65 kcal/g Fat = 9.45 kcal/g</p> Signup and view all the answers

    Which of the following statements accurately describes cellular respiration?

    <p>It is an amphibolic process.</p> Signup and view all the answers

    Plants have specialized organs for gas exchange.

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

    What are the alternatives to carbohydrates that can be used as respiratory substrates?

    <p>Fats and proteins</p> Signup and view all the answers

    What type of respiration occurs when carbohydrates or fats are oxidized inside the cell?

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

    Plants require large volumes of gases for respiration during photosynthesis.

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

    What is the primary end product of aerobic respiration?

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

    Plants utilize __________ respiration when no oxygen is present.

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

    Match the type of respiration with its key characteristic:

    <p>Aerobic = Complete oxidation to CO2 and H2O Anaerobic = Partial breakdown producing lactic acid or ethanol Floating respiration = Oxidation of carbohydrates or fats Protoplasmic respiration = Oxidation of proteins in starved cells</p> Signup and view all the answers

    How many molecules of ATP are gained from anaerobic respiration for each molecule of glucose?

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

    During aerobic respiration, oxygen acts as the final hydrogen acceptor.

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

    Name an example of a substance that can act as a hydrogen acceptor during alcoholic fermentation.

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

    Study Notes

    Cellular Respiration

    • Oxidation of C–C single bonds in complex compounds releases energy and synthesizes ATP.
    • Energy is released gradually through a series of enzyme-controlled reactions to prevent excessive heat generation.
    • ATP serves as the energy currency of the cell, breaking down when energy is needed.
    • Respiratory substrates primarily include carbohydrates (mainly glucose), fats, proteins, and organic acids.
    • Gross calorific values:
      • Carbohydrates: 4.1 kcal/g
      • Proteins: 5.65 kcal/g
      • Fats: 9.45 kcal/g
    • Physiological values:
      • Carbohydrates: 4.0 kcal/g
      • Proteins: 4.0 kcal/g
      • Fats: 9.0 kcal/g
    • Sequence of use for respiratory substrates: carbohydrates → fats → proteins.
    • Organic acids, such as malic acid, can also serve as respiratory substrates under specific conditions.

    Features of Cellular Respiration

    • Cellular respiration is an amphibolic process, producing carbon skeletons used for synthesizing other molecules.
    • It is an exergonic process, as it releases significant energy from breaking C–C bonds.

    Respiration in Plants

    • Plants lack specialized organs for gas exchange, relying on stomata and lenticels.
    • Each plant part manages its gas exchange, resulting in minimal gas transport needs.
    • Gas exchange demands in plants are low compared to animals.
    • While photosynthesis occurs, O2 is released, alleviating O2 availability issues for cells.
    • Gas diffusion distances are short within the plant, facilitating access to air by most cells.
    • Parenchyma cells create air spaces that further enhance gas exchange.

    Types of Respiration

    Based on Respiratory Substrates

    • Floating Respiration: Involves oxidation of carbohydrates or fats, utilizing these substrates stored within the cell.
    • Protoplasmic Respiration: Involves oxidation of proteins, occurring in starved cells as proteins are constituents of protoplasm.

    Based on Presence of Oxygen

    • Aerobic Respiration:

      • Complete oxidation of glucose yielding CO2 and H2O.
      • Intermolecular respiration with a yield of 36 or 38 ATP molecules per glucose.
      • NADH is oxidized vigorously to NAD+; O2 serves as the final hydrogen acceptor.
      • Reaction: C6H12O6 + 6O2 → 6CO2 + 12H2O + 686 kcal.

    • Anaerobic Respiration/Fermentation:

      • Partial breakdown of glucose producing lactic acid or ethanol and CO2.
      • Intramolecular respiration with a yield of only 2 ATP molecules per glucose.
      • NADH oxidation occurs slowly; hydrogen acceptors include acetaldehyde (alcoholic fermentation) or pyruvate (lactic acid fermentation).
      • Reaction: C6H12O6 → 2CH3CH2OH + 2CO2 + less than 7% of energy of glucose.

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    Description

    This quiz delves into the intricate process of cellular respiration, highlighting the oxidation of various substrates and the generation of ATP. It explores energy release, the efficiency of different respiratory substrates, and the significance of cellular respiration in metabolism.

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