Biology Krebs Cycle and Glycolysis Quiz
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Questions and Answers

What is the Respiratory Quotient (RQ) formula?

  • RQ = O2 ÷ CO2
  • RQ = CO2 × O2
  • RQ = CO2 ÷ O2 (correct)
  • RQ = O2 - CO2

    • The RQ value for glucose during aerobic respiration is 0.5.

    False

    What does an RQ value of 1 indicate about the respiratory process?

    Equal amounts of carbon dioxide are produced and oxygen is taken in.

    During the complete breakdown of glucose, ___ molecules of oxygen are used and ___ molecules of carbon dioxide are produced.

    <p>6, 6</p> Signup and view all the answers

    Match the respiratory substrates with their typical RQ values:

    <p>Carbohydrates = 1 Lipids = 0.7 Proteins = 0.8 Glucose = 1</p> Signup and view all the answers

    What is produced during one cycle of the Krebs Cycle?

    <p>1 ATP, 3 NADH, 1 FADH2, 2 CO2</p> Signup and view all the answers

    The Krebs Cycle only occurs once for each glucose molecule.

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

    What molecule is regenerated during the Krebs Cycle?

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

    The Krebs Cycle is also known as __________.

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

    Which of the following is NOT a product of the Krebs Cycle?

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

    Match the following products with their respective quantities produced in two cycles of the Krebs Cycle:

    <p>ATP = 2 NADH = 6 FADH2 = 2 CO2 = 4</p> Signup and view all the answers

    What type of reaction leads to the release of CO2 during the Krebs Cycle?

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

    Citrate undergoes oxidation and helps reduce NAD and FAD.

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

    What is the main product of glycolysis?

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

    Glycolysis requires oxygen to occur.

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

    How many ATP molecules are net gained during glycolysis?

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

    During glycolysis, glucose is phosphorylated using ____ molecules of ATP.

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

    Which molecule is used to collect hydrogen ions during glycolysis?

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

    What happens to triose phosphate during glycolysis?

    <p>It loses hydrogen and forms pyruvate.</p> Signup and view all the answers

    Match the following glycolysis processes with their outcomes:

    <p>Phosphorylation of glucose = Triose phosphate is formed Oxidation of triose phosphate = Pyruvate and reduced NAD are produced Net ATP production = 2 ATP molecules Anaerobic conditions = Lactic acid is produced</p> Signup and view all the answers

    Four molecules of ATP are produced during glycolysis, but only two are net gained.

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

    What is produced at the end of oxidative phosphorylation?

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

    Oxygen is the final electron acceptor in the electron transport chain.

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

    What model describes the mechanism of oxidative phosphorylation?

    <p>Chemiosmotic theory</p> Signup and view all the answers

    The protons return to the matrix through the enzyme __________.

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

    Match the following components of oxidative phosphorylation with their roles:

    <p>NADH = Donates hydrogen atoms to the electron transport chain Electron transport chain = Series of proteins transferring electrons ATP synthase = Synthesizes ATP from ADP Water = Final product formed from oxygen, protons, and electrons</p> Signup and view all the answers

    How are protons transported across the inner mitochondrial membrane?

    <p>By electron transport chain proteins</p> Signup and view all the answers

    The inner mitochondrial membrane is permeable to hydrogen ions.

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

    What process occurs when protons move down their concentration gradient?

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

    What does the variable 'x' represent in the respirometer experiment?

    <p>Volume of oxygen consumed</p> Signup and view all the answers

    The value of 'y' always indicates a positive change in gas volume.

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

    In the given example, what is the calculated RQ value for the blow fly larvae?

    <p>0.72</p> Signup and view all the answers

    To calculate the volume of oxygen consumed, the formula is πr²h, where 'r' is the radius of the __________.

    <p>capillary tube</p> Signup and view all the answers

    Match the following variables with their meanings:

    <p>x = Volume of oxygen consumed y = Volume of gas change considering carbon dioxide r = Radius of the capillary tube h = Distance moved by the manometer fluid</p> Signup and view all the answers

    When performing the experiment, what happens when the manometer fluid moves upwards?

    <p>It signifies a positive value.</p> Signup and view all the answers

    The formula for calculating RQ is applicable only to insects.

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

    What is the significance of removing the soda-lime from both tubes in the experiment?

    <p>To measure only the change in gas volume without interference from carbon dioxide absorption.</p> Signup and view all the answers

    Study Notes

    The Krebs Cycle

    • The Krebs Cycle is a series of reactions that occurs in the matrix of mitochondria.
    • It uses acetyl CoA from the link reaction and regenerates oxaloacetate.
    • It produces reduced NAD, reduced FAD, and ATP.
    • Oxaloacetate is regenerated through redox reactions, decarboxylation, oxidation (dehydrogenation), and substrate-linked phosphorylation.
    • Decarboxylation of citrate releases two CO2 molecules as waste gas.
    • Oxidation (dehydrogenation) of citrate releases H atoms that reduce coenzymes NAD and FAD, which are later used in oxidative phosphorylation.
    • Substrate-linked phosphorylation transfers a phosphate from an intermediate to ADP, forming 1 ATP.
    • Two cycles are required per glucose molecule because two acetyl-CoA are produced.
    • Products of two cycles are:
      • Two ATP
      • Six NADH (reduced NAD)
      • Two FADH2 (reduced FAD)
      • Four CO2

    Glycolysis

    • It is the first stage of respiration.
    • It doesn't require oxygen and is therefore the first step for both aerobic and anaerobic respiration.
    • Glucose is only partially oxidized.
    • It takes place in the cytoplasm of the cell.
    • It involves trapping glucose by phosphorylation and oxidizing triose phosphate.
    • It produces:
      • Two pyruvate molecules which move to the matrix of mitochondria for the link reaction.
      • Net gain of 2 ATP.
      • Two reduced NAD, which are used during oxidative phosphorylation.
    • Under anaerobic conditions, it produces lactic acid or lactate instead of pyruvate.
    • Steps of glycolysis involve:
      • Phosphorylation of glucose: Two ATP molecules are used to phosphorylate glucose, producing two molecules of triose phosphate and two ADP.
      • Oxidation of triose phosphate: Triose phosphate loses hydrogen, forming two pyruvate molecules. The hydrogen ions are collected by NAD, reducing the coenzyme to two reduced NAD or NADH. A net gain of two ATP molecules occurs.

    The Electron Transport Chain

    • It is the last stage of aerobic respiration.
    • It takes place at the inner mitochondrial membrane.
    • It results in the production of many ATP molecules and the production of water from oxygen.
    • The chemiosmotic theory explains how energy is used:
      • Energy from electrons is passed through a chain of proteins in the membrane (electron transport chain).
      • This energy pumps protons (hydrogen ions) against their concentration gradient into the intermembrane space.
      • Protons flow by facilitated diffusion through ATP synthase into the matrix.
      • The energy of protons flowing down their concentration gradient is harnessed to phosphorylate ADP into ATP by ATP synthase.
    • Outline of oxidative phosphorylation:
      • Reduced NAD (NADH) and reduced FAD (FADH2) from the Krebs Cycle donate hydrogen atoms.
      • Hydrogen atoms split into protons (H+ ions) and electrons.
      • High-energy electrons enter the electron transport chain and release energy as they move through the chain.
      • The energy released is used to transport protons across the inner mitochondrial membrane from the matrix into the intermembrane space.
      • A concentration gradient of protons is established.
      • Protons return to the matrix via ATP synthase, providing energy for ATP synthesis.
      • Oxygen acts as the final electron acceptor, combining with protons and electrons to form water.
    • The electron transport chain is made up of a series of membrane proteins/electron carriers.
      • They are positioned close together to allow electrons to pass from carrier to carrier.
      • They pump protons across the membrane to establish the concentration gradient.

    Respiratory Quotient (RQ)

    • The RQ is the ratio of carbon dioxide molecules produced to oxygen molecules taken in during respiration.
    • Formula: RQ = CO2 ÷ O2.
    • Carbohydrates, lipids, and proteins have different RQ values due to the number of carbon-hydrogen bonds in each molecule:
      • More carbon-hydrogen bonds mean more hydrogen atoms for proton gradient formation, leading to more ATP production and higher oxygen requirement.
    • When glucose is aerobically respired, equal amounts of carbon dioxide and oxygen are produced, resulting in an RQ value of 1.
    • RQ can be calculated using a respirometer, which measures the volume of oxygen consumed (x) and the change in gas volume (y) after removing soda-lime.
    • Equation for calculating RQ values: RQ = (x + y) ÷ x.

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    Description

    Test your knowledge on the Krebs Cycle and Glycolysis, two crucial biochemical pathways in cellular respiration. This quiz explores the details of reactions, products, and the importance of these processes in energy production. Perfect for biology students looking to reinforce their understanding.

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