Topic 8 1 IB TB questions and answers by i286R30


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     1. Explain the process of aerobic respiration including oxidative phosphorylation.
                                                                                                  (Total 8 marks)

2.     glucose converted to pyruvate (two molecules);
       by glycolysis;
       pyruvate enters the mitochondria;
       pyruvate converted to acetyl CoA / ethyl CoA;
       by oxidative decarboxylation / NADH and CO2 formed;
       fatty acids / lipids converted to acetyl CoA;
       acetyl groups enter the Krebs cycle (accept acetyl CoA);
       FAD / NAD+ accepts hydrogen (from respiratory substrates) to form NADH / FADH2;
       FADH2 / NADH donates electrons / hydrogen to electron transport chain (reject
       donates H+);

       electrons release energy as they pass along the chain;
       oxygen final electron acceptor;
       production of water;
       builds up proton gradient / protons pumped across inner membrane;
       protons flow into matrix of mitochondria through ATPase;
       ATP produced;
       produces 36 / 38 ATP (per glucose);                                                8 max
       Accept any appropriate terminology for NAD and FAD.
       (Plus up to [2] for quality)

3.     Which is not a product of the Krebs cycle?

       A.    CO2

       B.    NADH + H+

       C.    Pyruvate

       D.    ATP
                                                                                                  (Total 1 mark)

4.     C

5.   How many ATP molecules (net yield) are produced per molecule of glucose as a direct result of glycolysis?

     A.    2

     B.    4

     C.    10

     D.    38
                                                                                                        (Total 1 mark)

6.   A

7.   Which way do the protons flow when ATP is synthesized in mitochondria?

     A.    From the inner matrix to the intermembrane space

     B.    From the intermembrane space to the inner matrix

     C.    From the intermembrane space to the cytoplasm

     D.    From the cytoplasm to the intermembrane space
                                                                                                        (Total 1 mark)

8.   B

9.   What accumulates in the inter-membrane space of the mitochondrion during electron transport?

     A.    ATP

     B.    Electrons

     C.    Protons (hydrogen ions)

     D.    Oxygen
                                                                                                        (Total 1 mark)

10.   C

11.   What is the sequence of stages during the conversion of glucose into pyruvate in glycolysis?

      A.    Lysis         phosphorylation of sugar         oxidation

      B.    Lysis         oxidation         phosphorylation of sugar

      C.    Phosphorylation of sugar          lysis        oxidation

      D.    Phosphorylation of sugar          oxidation         lysis
                                                                                                     (Total 1 mark)

12.   C

13.   How many molecules of acetyl CoA (ethanoyl CoA) does the oxidation of the fatty acid stearic acid produce?

                                                  CH 3
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                         Stearic acid
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2
                                                  CH 2

      A.    2

      B.    6

      C.    9

      D.    18

14.   C

15.   Which of the following produce ATP in mitochondria?

      A.    The movement of protons from the matrix to the intermembrane space

      B.    The movement of protons from the intermembrane space to the cytoplasm

      C.    The splitting of water molecules and the movement of electrons to oxygen

      D.    The movement of protons from the intermembrane space to the matrix

16.   D

17.   Explain the process of aerobic cellular respiration.
                                                                                       (Total 8 marks)

18.   glucose is broken down to pyruvate in the cytoplasm;
      with a small yield of ATP / net yield of 2 ATP;
      and NADH + H+ / NADH;
      aerobic respiration in the presence of oxygen;
      pyruvate converted to acetyl CoA;
      acetyl CoA enters Krebs cycle;
      Krebs cycle yields a small amount of ATP / one ATP per cycle;
      and FADH2 / FADH + H+ / NADH / NADH + H+ /
      reduced compounds / electron collecting molecules;
      these molecules pass electrons to electron transport chain;
      oxygen is final electron acceptor / water produced;
      electron transport chain linked to creation of an electrochemical gradient;
      electrochemical gradient / chemiosmosis powers creation of ATP;
      through ATPase;

19.   During which process are oxygen molecules directly involved during cellular respiration?

      A.    Glycolysis

      B.    Krebs cycle

      C.    Oxidation of pyruvate to acetyl CoA

      D.    Accepting electrons at the end of the electron transport chain
                                                                                                 (Total 1 mark)

20.   D

21.   What is the key function of acetyl CoA in cellular respiration?

      A.    Involved in carbohydrate and fatty acid metabolism

      B.    Used in anaerobic respiration to oxidize pyruvate

      C.    Introduces amino acids into the Krebs cycle

      D.    Used as a hydrogen carrier in the link reaction
                                                                                                 (Total 1 mark)

22.   A

23.   The diagram below shows the three stages of glycolysis. Which processes are indicated by I, II and III?

                                       6-carbon glucose


                               6-carbon glucose phosphate


                        3-carbon                           3-carbon
                     sugar phosphate                    sugar phosphate


                              3-carbon                 3-carbon
                              pyruvate                 pyruvate

                          I                            II                    III
       A.    Lysis                           Phosphorylation        Oxidation and ATP
       B.    Oxidation and ATP               Phosphorylation        Lysis
       C.    Phosphorylation                 Lysis                  Oxidation and ATP

       D.    Phosphorylation            Oxidation and ATP          Lysis
                                                                                                             (Total 1 mark)

24.   C

25.   Up to two additional marks are available for the construction of your answers.

      (a)   Draw and label a mitochondrion as seen in electron micrographs.

      (b)   Outline the cellular locations of different named processes in both photosynthesis and cell respiration.

      (c)   Explain the energy flow in a food chain as exemplified by a pyramid of energy.
                                                                                                          (Total 20 marks)

26.   (a)   Award [1] for each of the following clearly drawn and correctly labelled.
            outer membrane;
            inner membrane – folded into thin cristae;
            cristae – shown as thin;
            intermembrane space – shown as thin;
            (70S) ribosomes;
            ATP synthase – shown on the inner membrane surface;
            (naked) loop of DNA;                                                          4 max

(b)   photosynthesis:                                                             3 max
      chloroplasts / photosystems: for light absorption / photosynthesis;
      stroma: light-independent reactions / Calvin cycle;
      thylakoid membranes of chloroplast: chemiosmosis /
      photophosphorylation / light dependent reactions;
      thylakoid space: build up H+ concentration gradient;
      inner membrane of thylakoid: electron transfer;
      inner membrane: ATP synthesis;
      cell respiration:                                                           3 max
      mitochondria: for ATP production / aerobic respiration;
      cytoplasm: glycolysis / matrix: Krebs cycle / oxidative
      phosphorylation / link reaction;
      double / inner membranes of mitochondria: chemiosmosis /
      oxidative phosphorylation;
      intermembrane space: build-up H+ concentration gradient;
      inner membrane of mitochondria: electron transfer;
      inner membrane: ATP synthesis;                                              6 max
      Answers must indicate location and process to receive a mark.
      Do not award a mark if it is ambiguous whether the candidate is discussing photosynthesis or

(c)   a food chain includes a producer and consumers;
      represents the direction of energy flow;
      energy loss occurs between trophic levels;
      due to material not consumed / assimilated;
      and from heat loss due to cell respiration;
      energy passed on from one level to next is 10–20%;
      which limits length of food chain;
      photosynthesis / producers convert solar energy to chemical
      energy (in organic molecules);
      consumers obtain necessary energy from eating organisms
      of previous trophic level;
      an energy pyramid shows the flow of energy from one tropic
      level to the next (in a community);
      units are energy per unit area per unit time / J m–2 yr–1;
      Pyramid of energy – properly drawn, each level no more than
      one fifth the width of the level below it, with three correctly
      labelled trophic levels eg producer, primary consumer;                      8 max
(Plus up to [2] for quality)

27.   Up to two additional marks are available for the construction of your answers.

      (a)   Draw a labelled diagram showing the structure of a plasma membrane.

      (b)   Outline the role of chlorophyll and the effects of temperature, light intensity and carbon dioxide
            concentration on the rate of photosynthesis.

      (c)   Explain the production of energy during aerobic respiration from pyruvate that has been produced by
                                                                                                           (Total 20 marks)

28.   (a)   Award [1] for each of the following clearly drawn and labelled correctly.
            a double layer of lipid / phospholipid molecules - with hydrophilic heads and
            hydrophobic tails;
            an integral protein - passing completely through the lipid bilayer;
            a peripheral protein - shown on the surface and not penetrating the lipid bilayer;
            an integral protein with a pore passing through its entire length / a glycoprotein
            with the carbohydrate components shown / cholesterol as component in bilayer;        4

      (b)   chlorophyll is composed of a number of pigments;
            absorb different colours of light;
            mainly red and blue absorbed;
            green light reflected;
            temperature increases rate;
            up to a point where enzymes denature;
            light intensity increases rate;
            up to a point where maximum absorbance can occur;
            carbon dioxide increases rate;
            up to a point where fixation is at a maximum;                                  6 max

(c)   Krebs cycle:[3 max]
      in matrix of mitochondrion;
      oxidation / removal of hydrogen by NAD and FAD;
      substrate level phosphorylation;
      Electron transport chain:[5 max]
      transfer of hydrogen to inner membrane carriers;
      hydrogen ion pumped across inner membrane;
      creates a concentration gradient;
      electron transferred between carriers;
      hydrogen ion passes down concentration gradient;
      through ATPase complex;
      oxygen is final acceptor forming water;                   8 max
                                                         (Plus up to [2] for quality)


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