Topic 3 1 3 3HL

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Topic 3 1 3 3HL Powered By Docstoc
					Review Questions – Topic 3 – Water, Elements, and Macromolecule

1.   Many elements are necessary to form biochemicals required by living organisms. For each
     element below, state the name of one molecule containing the element and state the function of
     the molecule.

     (a)    Iron:                                    Molecule.....................................................................................

                                                     Function......................................................................................


                                                                                                                                                            (2)

     (b)    Phosphorus:                              Molecule.....................................................................................

                                                     Function......................................................................................


                                                                                                                                                        (2)
                                                                                                                                            (Total 4 marks)



2.   Describe the significance of water to living organisms.
                                                                                                                                            (Total 6 marks)



3.   The diagrams below show various molecular structures.

     I.                                                                                     II.                                 O
                                                              O
                                                                                                       HOH 2 C                                H
            CH 3           (CH 2) n                C
                                                                                                                  C                           C
                                                              OH
                                                                                                                  H H                  H      OH
                                                                                                                        C              C

                                                                                                                        OH             OH

     III.           CH 2 OH                                                                 IV.                             R
                                                                                                      H                                           O
                    C         O          H
            H                                                                                                    N          C          C
                    H
            C       OH        H          C                                                            H                                           OH
                                                                                                                            H
            OH      C         C          OH

                    H         OH

     (a)    Identify which of the diagrams represent

            (i)     the structure of glucose.

                    .....................................................................................................................................
                                                                                                                                                            (1)

                                                                                                                                                             1
               (ii)      the structure of amino acids.

                         .....................................................................................................................................
                                                                                                                                                                 (1)

               (iii)     the structure of fatty acids.

                         .....................................................................................................................................
                                                                                                                                                                 (1)

     (b)       Discuss which of the molecules are most similar in structure.

               ...............................................................................................................................................
                                                                                                                                                              (3)
                                                                                                                                                  (Total 6 marks)



4.   Which molecule represents ribose?

     A.                                                                        B.
                           CH 2 OH                                                                                  O

                  H        C        O       H                                                  H                    C                  H

                           H                                                                             C                   O
                  C                         C
                           OH H                                                                H
                  OH C                      OH                                                           N
                                    C
                                                                                              H                     H
                           H        OH

     C.         H 2C             OH                                            D.                                       O
                                                                                               HOH 2 C                               H

                  HC             OH                                                                       C                          C
                                                                                                                H               H
                H 2C             OH                                                                       H                         OH
                                                                                                                C              C

                                                                                                                OH             OH
                                                                                                                                                                 (1)


5.   Outline how monosaccharides are converted into polysaccharides.

     ...............................................................................................................................................
                                                                                                                                                  (Total 2 marks)



6.   Draw the structure of a fatty acid.
                                                                                                                                                   (Total 1 mark)



7.   Outline the use of carbohydrates and lipids in energy storage.
                                                                                                                                                  (Total 5 marks)



                                                                                                                                                                  2
8.    The complex structure of proteins can be explained in terms of four levels of structure, primary,
      secondary, tertiary and quaternary.

      (a)    Primary structure involves the sequence of amino acids that are bonded together to form a
             polypeptide. State the name of the linkage that bonds the amino acids together.

             ...............................................................................................................................................
                                                                                                                                                               (1)

      (b)    Beta pleated sheets are an example of secondary structure. State one other example.

             ...............................................................................................................................................
                                                                                                                                                               (1)

      (c)    Tertiary structure in globular proteins involves the folding of polypeptides. State one
             type of bond that stabilizes the tertiary structure.

             ...............................................................................................................................................
                                                                                                                                                               (1)
      (d)    Outline the quaternary structure of proteins.

             ...............................................................................................................................................
                                                                                                                                                            (2)
                                                                                                                                                (Total 5 marks)

9.    Consider the metabolic pathway shown below.

                                                   1                  2                  3                 4
                                         A                  B                  C                 D                  E

      If there is end-product inhibition, which product (B to E) would inhibit which enzyme (1 to 4)?

                   Product                   Enzyme
        A.              C                         4
        B.              B                         3
        C.              B                         4
        D.              E                         1
                                                                                                                                                               (1)

10.   Which of the following reactions occurs when a dipeptide is formed from amino acids?

      A.     Hydrolysis

      B.     Denaturation

      C.     Condensation

      D.     Oxidation
                                                                                                                                                               (1)



11.   (a)    State one named example of a fibrous protein and one named example of a globular
             protein.

             Fibrous: ...........................................                    Globular: ...........................................
                                                                                                                                                               (2)

                                                                                                                                                                3
      (b)   Outline the effect of enzymes on the reactions they catalyse.
                                                                                                                                                              (2)

      (c)   The rate of cellular respiration is controlled by the allosteric inhibition of
            phosphofructokinase by ATP. Phosphofructokinase is the first enzyme in the respiration
            pathway. Explain the meaning of allosteric inhibition using this example.
                                                                                                                                                           (4)
                                                                                                                                               (Total 8 marks)

12.   Which is not a primary function of protein molecules?

      A.    Hormones

      B.    Energy storage

      C.    Transport

      D.    Structure
                                                                                                                                                              (1)
13.   (a)   Explain the significance of secondary structure to the structure of a protein.

            ...............................................................................................................................................
                                                                                                                                                              (3)

      (b)   State the name of a competitive enzyme inhibitor.

            ...............................................................................................................................................
                                                                                                                                                              (1)

      (c)   Outline the difference between competitive and non-competitive enzyme inhibitors.

            ...............................................................................................................................................
                                                                                                                                                           (2)
                                                                                                                                               (Total 6 marks)


14.   The diagram below shows a channel protein in a membrane. Which parts of the surface of the
      protein would be composed of polar amino acids.




      A.    I and II only

      B.    II and III only

      C.    III and IV only

      D.    I and IV only
                                                                                                                                                              (1)

                                                                                                                                                               4
15.   Which structure represents an amino acid?

              A.                             H                                             B.                            H
                          H                                   O                                        H                                   O
                                  N         C         C                                                        N         C         C

                          H                                   H                                        H                                   SH
                                             H                                                                           OH



              C.                            H                                             D.                             H
                         H                                   O                                        H                                   O
                                 N         C         C                                                        N         C         C

                         H                                   H                                        H                                   OH
                                            OH                                                                           H
                                                                                                                                                              (1)



16.   (a)   Define the term active site of an enzyme.

            ...............................................................................................................................................
                                                                                                                                                              (1)
      (b)   Outline how enzymes catalyze biochemical reactions.
                                                                                                                                                              (2)

      (c)   Explain the effect of pH on enzyme activity.
                                                                                                                                                              (3)

      (d)   State three functions of lipids.
                                                                                                                                                           (2)
                                                                                                                                               (Total 8 marks)



17.   Explain the effects of temperature, pH and substrate concentration on enzyme activity.
                                                                                                                                               (Total 8 marks)

18.   What can reduce the effect of a competitive inhibitor of an enzyme?

      A.    Decrease the temperature at which the reaction takes place.

      B.    Increase the temperature at which the reaction takes place.

      C.    Increase the substrate concentration.

      D.    Add a non-competitive inhibitor.
                                                                                                                                                              (1)


19.   Explain how allosteric control of metabolic pathways by end-product inhibition includes
      negative feedback and non-competitive inhibition.
                                                                                                                                               (Total 8 marks)




                                                                                                                                                               5
20.   What effect do enzymes have on the activation energy of exergonic and endergonic reactions?

            Activation energy of Activation energy of
            exergonic reactions endergonic reactions
       A.        increases              increases
       B.        decreases              decreases
       C.        increases              decreases
       D.        decreases              increases
                                                                                                       (1)



21.   Outline two examples of the commercial application of enzymes in biotechnology.
                                                                                           (Total 6 marks)



22.   Which of the following could cause denaturation of an enzyme?

      A.    Substrate concentration

      B.    A competitive inhibitor

      C.    High temperature

      D.    Low salt concentration
                                                                                                       (1)




                                                                                                        6
23.   The graph below shows the effect of changing the substrate concentration on an enzyme
      controlled reaction.


                                                          40 % substrate
                                                             20 % substrate
                                                                   10 % substrate
                  Amount of product formed
                                                                         5 % substrate



                                                                              2.5 % substrate

                                                                              0 % substrate
                                                                Time

      What is the correct interpretation of these data?

      A.    The rate of reaction increases continuously with increase in substrate concentration.

      B.    The rate of reaction decreases continuously with increase in substrate concentration.

      C.    The rate of reaction increases up to a point and then remains constant.

      D.    The rate of reaction is not affected by any change in the substrate concentration.
                                                                                                      (1)



24.   In the enzyme controlled pathway shown below, which compound is most likely to inhibit
      enzyme (w)?

                                   enzyme       enzyme         enzyme          enzyme
                                      w            x              y               z
                     Precursor               I            II            III                  IV

      A.    I

      B.    II

      C.    III

      D.    IV
                                                                                                      (1)




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posted:11/29/2011
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