Syllabus Edition

First teaching 2023

First exams 2025

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Structure of Nucleic Acids & Replication of DNA (CIE AS Biology)

Exam Questions

3 hours46 questions
11 mark

Which base pair has a mistake?

q1-cie-6-1

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    21 mark

    Which row correctly identifies the features of DNA and RNA molecules?     

      DNA and RNA both contain a 5- carbon sugar DNA and RNA contain both purine and pyrimidine bases forms hydrogen bonds with bases in RNA molecules

    A

    B

    C

    D

    X

    X

    X

    X

    key

    = correct statement

    X= incorrect statement

                                 

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      31 mark

      DNA was extracted from the pancreas of a walrus and a human liver cell.

      In which way did the DNA molecules differ?

      • the ratio of guanine to cytosine

      • the type of pentose sugar

      • the types of nucleotides

      • the sequence of the nucleotides 

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      41 mark

      Which row correctly describes guanine?

        ring structure component on nucleotide strand it is attached to complementary base
      A double pentose sugar cytosine
      B double phosphate cytosine
      C single phosphate cytosine
      D single pentose sugar thymine

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        51 mark

        What is the minimum number of hydrogen bonds in a length of DNA containing 900 base pairs?

        • 450

        • 900

        • 1800

        • 2700

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        61 mark

        The diagram shows part of a DNA molecule

        screenshot-2023-05-11-164704

         

        Which part is a nucleotide? 

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          71 mark

          The diagram shows the outcomes from four different models of DNA reproduction after one nuclear division. The parent DNA is shown in black and the newly synthesized DNA is shown in grey.

          screenshot-2023-05-11-170305

          Which diagram shows conservative DNA replication?

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            81 mark

            This diagram shows a section of a DNA molecule.

            screenshot-2023-05-11-170604

            What is part X on the diagram?

            • Cytosine

            • Uracil

            • Thymine

            • Guanine

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            91 mark

            This diagram shows a section of DNA

            screenshot-2023-05-11-170759

            How many hydrogen bonds would be involved in holding these two strands together?

            • 10

            • 11

            • 12

            • 14

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            101 mark

            Which row correctly describes adenine on a strand of DNA?

             

            component on nucleotide strand it is attached to

            complementary base

            A

            deoxyribose

            uracil

            B

            ribose

            uracil

            C

            deoxyribose

            thymine

            D

            ribose

            thymine

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              11 mark

              Which base pair has the mistake?  

              screenshot-2023-05-11-171257

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                21 mark

                A short piece of DNA 19 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands.  Some of the results are shown below

                  number of nucleotide bases

                strand 1 

                strand 2

                A

                8

                -

                T

                -

                8

                G

                -

                3

                C

                -

                4

                How many nucleotides containing adenine (A) were present in strand 2?

                • 2

                • 4

                • 6

                • 8

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                31 mark

                During semi-conservative replication of DNA, the following processes occur:

                1

                Free nucleotides are hydrogen bonded to those on the exposed strand.

                2

                The cell receives the signal to begin to divide.

                3

                Hydrogen bonds are broken between the complementary base pairs.

                4

                Covalent bonds form between adjacent nucleotides on the same strand.

                5

                The DNA double helix is unwound.

                Which is the correct order of the processes?

                • 2 → 5 → 3 → 4 → 1

                • 2 → 5 → 3 → 1 → 4

                • 2 → 1 → 4 → 3 → 5

                • 2 → 1 → 5 → 4 → 3

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                41 mark

                The table shows the percentages of bases in DNA from various types of cell.

                source of DNA

                adenine

                cytosine

                guanine

                thymine

                human hair

                30

                20

                21

                Z

                human liver

                W

                40

                40

                11

                dog liver

                24

                26

                24

                26

                mouse bone marrow

                23

                X

                27

                25

                sunflower leaf

                11

                41

                Y

                10

                What is a valid deduction from this data?

                • W = 9   X = 24   Y = 38   Z = 29

                • W= 9   X = 26   Y = 37   Z = 31

                • W= 9   X = 25   Y = 38   Z = 29

                • W= 10   X = 25   Y = 37   Z = 30 

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                51 mark

                Which of the following would be a result of analysing a DNA molecule?

                • An equal ratio of pentose sugars to phosphates and an equal ratio of thymine to adenine bases.

                • Twice as many pentose sugars as phosphates and an equal ratio of guanine to cytosine bases.

                • An equal ratio of hexose sugars to phosphates and an equal ratio of thymine to cytosine bases.

                • Twice as many hexose sugars as phosphates and an equal ratio of guanine to adenine bases.

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                61 mark

                The diagram shows part of a DNA molecule

                screenshot-2023-05-11-172846

                Which row correctly describes the highlighted sections of DNA?

                 

                contains a base

                hydrogen bonding present

                A

                2, 3 and 4

                1 only

                B

                2, 3 and 4

                3 only

                C

                1 ,2, 3 and 4

                3 and 4 only

                D

                1 ,2, and 4

                3 only

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                  71 mark

                  In 1957, Meselson and Stahl conducted an experiment that provided overwhelming evidence to support the theory than DNA replication was semi-conservative.  They used E. coli which has a generation time of around one hour.

                  Here are the steps in their experiment in a mixed-up order

                  1

                  Bacteria contain either all 14N DNA or hybrid DNA

                  2

                  Bacteria grown in a 15N medium for many generations

                  3

                  Bacteria transferred to a 14N medium and sampled every hour

                  4

                  All bacteria contain hybrid DNA (14N DNA and 15N DNA).

                  5

                  All bacteria contain 15N DNA

                  • 4 → 3 → 1 → 2 → 5

                  • 3 → 1 → 2 → 4 → 5

                  • 5 → 4 → 3 → 1 → 2

                  • 2 → 5 → 3 → 4 → 1

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                  81 mark

                  The diagram shows part of an RNA molecule.

                  screenshot-2023-05-11-173404

                  Which row of the table below is correct?

                   

                   

                  uracil

                  phosphate

                  ribose

                  guanine

                  A

                  B

                  C

                  D

                  W

                  W

                  X

                  X

                  Z

                  Y

                  Z

                  Y

                  Y

                  Z

                  Y

                  Z

                  X

                  X

                  W

                  W

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                    91 mark

                    Which nucleic acid bases are pyrimidines?

                    • adenine and guanine

                    • thymine and adenine

                    • thymine and guanine

                    • cytosine and uracil

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                    101 mark

                    How many mistakes are there in this DNA sequence?

                    screenshot-2023-05-11-191445

                    • 1

                    • 2

                    • 3

                    • 4

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                    11 mark

                    A piece of DNA 153 base pairs long was analysed to find the number of nucleotide bases in each of the polynucleotide strands.  Some of the results are shown below

                      number of nucleotide bases


                    strand 1

                    strand 2

                    A



                    T
                    31


                    G
                    22


                    C
                    52


                    How many nucleotides containing Thymine (T) were present in strand 2?

                    • 22

                    • 29

                    • 34

                    • 48

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                    21 mark

                    What would be the result of analysing a DNA molecule 14 000 base pairs in length?

                    • 28 000 pentose sugars, 14 000 phosphates, an equal ratio of cytosine to thymine bases and an equal ratio of guanine to adenine bases

                    • 28 000 pentose sugars, 28 000 phosphates, an equal ratio of cytosine to guanine bases and an equal ratio of thymine to adenine bases

                    • 14 000 pentose sugars, 28 000 phosphates, an equal ratio of cytosine to thymine bases and an equal ratio of guanine to adenine bases

                    • 28 000 pentose sugars, 28 000 phosphates, an equal ratio of cytosine to thymine bases and an equal ratio of guanine to adenine bases

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                    31 mark

                    Meselson and Stahl proved that DNA replication was semi-conservative.  Bacteria were grown for many generations in a medium containing 15N (a heavy isotope of nitrogen). They were then transferred to a medium containing 14N (a lighter isotope of nitrogen). They were given time to replicate DNA and divide once. Their DNA was extracted, spun in a centrifuge and observed using ultraviolet light. They then repeated this experiment, this time allowing the bacteria to replicate DNA and divide twice.  Again, the DNA was extracted, spun in a centrifuge and observed using ultraviolet light.

                    screenshot-2023-05-11-192222

                    Which shows the predicted results after zero, one and two generations of replication in the medium with the light isotope?

                    • X = 0   Y = 1   Z = 2

                    • X = 0   Y = 2   Z = 1

                    • X = 2   Y = 1   Z = 0

                    • X = 2   Y = 0   Z = 1

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                    41 mark

                    The table shows the percentages of bases in DNA from various types of cell.

                    source of DNA

                    adenine

                    cytosine

                    guanine

                    thymine

                    human hair

                    30

                    20

                    21

                    29

                    human liver

                    9

                    40

                    40

                    11

                    dog liver

                    24

                    26

                    24

                    26

                    mouse bone marrow

                    23

                    26

                    27

                    24

                    sunflower leaf

                    11

                    41

                    38

                    10

                    What is a valid deduction from this data?

                    • Larger organisms have a greater thymine abundance.

                    • All cells have roughly the same amount of DNA.

                    • The structure of DNA in sunflower leaves and human liver is similar.

                    • The four bases exhibit complementary base pairing.

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                    51 mark

                    The diagram shows DNA strands that have undergone replication. The parent DNA is shown in black and the newly synthesised DNA is shown in grey.

                    screenshot-2023-05-11-192816

                    Which would be the resulting DNA strands formed after two cycles of semi-conservative replication?  

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                      61 mark

                      Which enzymes are needed for DNA replication?

                      1

                      Helicase 

                      2

                      DNA ligase 

                      3

                      RNA polymerase 

                      4

                      DNA polymerase 

                      • 1 and 2 only

                      • 2, 3 and 4 only

                      • 1, 2 and 4 only

                      • 1 and 4 only

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                      71 mark

                      Which diagram shows the bond linking the individual units of a nucleic acid?

                      screenshot-2023-05-11-193152

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                        81 mark

                        The following events occur in the replication of DNA.

                        Here are the steps in their experiment in a mixed-up order

                        1

                        opposite strands are separated 

                        2

                        free DNA nucleotides pair with complementary nucleotides on each strand 

                        3

                        bonds between complementary bases are formed 

                        4

                        bonds between complementary bases are broken 

                        5

                        phosphodiester bonds are formed 

                        Which is the correct order of the processes?

                        • 1 → 3 → 4 → 2 → 5

                        • 3 → 1 → 2 → 4 → 5

                        • 2 → 1 → 3 → 4 → 5

                        • 4 → 1 → 2 → 3 → 5

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                        91 mark

                        Which type of sugar and types of bonds are found in a DNA molecule?

                          type of sugar nucleotides in strand joined by adjacent strands joined by
                        A non-reducing phosphodiester bonds hydrogen bonds
                        B reducing phosphodiester bonds hydrogen bonds
                        C non-reducing ester bonds covalent and hydrogen
                        D reducing ester bonds covalent and hydrogen

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                          101 mark

                          In 1957, Meselson and Stahl conducted an experiment that proved that DNA replication was semi-conservative.  They took bacteria containing only 15N in their DNA and transferred them to a medium only containing 14N.  They allowed the bacteria to divide once then centrifuged the DNA to reveal the following results

                          screenshot-2023-05-11-195936

                          Which shows the predicted results after one generation in the medium with the light isotope?

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