IBBiology: HLDPTopic Questions2. Molecular Biology2.5 Nucleic Acids: Structure & DNA Replication

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First teaching 2014

Last exams 2024

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Nucleic Acids: Structure & DNA Replication (DP IB Biology: HL)

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2.5 Nucleic Acids: Structure & DNA Replication

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2.5 Nucleic Acids: Structure & DNA Replication

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1
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The following diagram represents the structure of a nucleotide.2-5-e-2

Which row of the following table correctly identifies all the components of this nucleotide?

  1 2 3
A. Adenine Pentose sugar Phosphate group
B. Phosphate group Adenine Pentose sugar
C. Pentose sugar Phosphate group Adenine
D. Phosphate group Pentose sugar Adenine

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    2
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    Which of the following statements only apply to RNA?

    I. The molecule is in the shape of a double helix, with antiparallel strands

    II. The four bases are adenine, cytosine, guanine, thymine

    III. Ribose is present as the pentose sugar in its nucleotides

    IV. It is a polymer formed by the linkage of many nucleotides

    • I and III

    • I, II and IV

    • II, III and IV

    • III and IV

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    3
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    The following diagram shows a section of a DNA molecule.

    2-5easyq3

    Which of these base pairs are not correct?

    • None

    • 1

    • 2

    • 3

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    4
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    Which of the following is not a reason why molecular models helped Crick and Watson discover the structure of DNA?

    • The DNA model could be adapted as their research delivered more information

    • It reduced the amount of time spent on "trial and error" cycles and enabled them to come to a faster conclusion

    • It represented their concepts of the three dimensional structure of DNA in order for further testing

    • It enabled Crick and Watson to communicate their findings about the structure of DNA in a clear, visible way

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    5
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    The diagram shows the outcomes from four different models of DNA replication after one nuclear division. The parent DNA is shown in black and the newly synthesised DNA is shown in grey.

    2-5easyq5

    Which diagram represents semi-conservative DNA replication?

    • 1

    • 2

    • 3

    • 4

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    11 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  
      A T G C
    Strand 1 8 - - -
    Strand 2 - 8 3 4

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

    • 2

    • 4

    • 6

    • 8

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    21 mark

    Which activity was not a direct contributor to Crick and Watsons' discovery of the double-helix structure of DNA?

    • Thin-layer chromatography.

    • X-ray molecular analysis.

    • Building physical models with clamps and stands.

    • Collaboration with scientists in other research institutions. 

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    31 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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    41 mark

    DNA is described as a double-helix, antiparallel structure. Which of the following statements best explains the term, 'antiparallel'? 

    • One strand possesses deoxyribose sugar, the opposite strand possesses ribose sugars. 

    • The nitrogenous bases invert their orientation on the sense strand versus the antisense strand.

    • The alignment of the sugar-phosphate backbone of each strand runs in opposite directions.

    • The alignment of the two strands of nucleotides runs in opposite directions.

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    51 mark

    The approximate angle of orientation ('twist') of one nucleotide in respect to its neighbouring nucleotide in a given strand of DNA is between 35 and 40 degrees. How many base pairs are required for the double-helix to twist by one whole turn? 

    • 5

    • 8

    • 10

    • 12

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    61 mark

    Which of the following statements about semi-conservative replication of DNA are correct? 

    1. DNA polymerase always works in the same direction along a strand of DNA, in the 3′ to 5′ direction.
    2. The action of DNA polymerase is followed by that of helicase.
    3. One strand of original DNA remains in each daughter molecule; the other strand has been made from free nucleotides.
    4. Crick and Watson proposed the hypothesis of semi-conservative replication, whereas experimental evidence was later provided by Meselson and Stahl.

    • I, III and IV

    • I and III

    • III and IV

    • I, II and IV

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    71 mark

    The diagram shows part of an RNA molecule. mcq-q7-ib-hl-biology

    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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      81 mark

      During the process of semi-conservative replication of DNA, which activity, relating to bonding, does not take place?.

      • Breaking of hydrogen bonds.

      • DNA polymerase forms an enzyme-substrate complex with free nucleotides. 

      • Formation of new covalent bonds between nucleotides.

      • Formation of new glycosidic bonds between deoxyribose molecules. 

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      91 mark

      The table shows the percentages of bases in DNA samples from various organisms.

      Source of DNA Adenine Cytosine Guanine Thymine
      Human liver 30 20 20 Z
      Chicken liver W 40 40 10
      Dog liver 24 26 24 26
      Mouse bone marrow 23 X 26 25
      Sunflower leaf 10 39 Y 12


      Which row of the table below correctly reflects the missing data values?

        W X Y Z
      A 9 24 38 30
      B 10 26 39 31
      C 10 26 39 30
      D 10 25 38 29

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        101 mark

        The simplified diagram represents a section of DNA in 2D form.

        mcq-q10-ib-hl-biology

        How many mistakes are there in this diagram? 

        • 0

        • 1

        • 3

        • 5

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        1
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        Which of the following would be the result of analysing a DNA molecule 14 000 base pairs in length?

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

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

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

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

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        2
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        Which of the following would not be considered an advantage of complementary base pairing in DNA?

        • It enables each DNA strand to act as a template for the formation of a new strand during replication

        • Hydrogen bonding between complementary bases stabilises the structure of the DNA molecule

        • It ensures genetic continuity between generations of cells so that they all contain the same genetic information as the parent cells

        • It plays an important role in maintaining the covalent bonds within the DNA molecule

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        3
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        Which of the rows in the following table correctly identifies the function of each enzyme listed?

          Helicase RNA polymerase DNA polymerase
        A. Breaks the hydrogen bonds between complementary DNA bases Links thymine to the adjacent nucleotide through covalent bonds Binds to a template DNA strand and pairs uracil up with adenine
        B. Responsible for the formation of hydrogen bonds between complementary DNA bases Binds to a template DNA strand and pairs uracil up with adenine Links thymine to the adjacent nucleotide through covalent bonds
        C. Breaks the hydrogen bonds between complementary DNA bases Binds to a template DNA strand and pairs uracil up with adenine Links thymine to the adjacent nucleotide through covalent bonds
        D. Binds to a template DNA strand and pairs uracil up with adenine Links thymine to the adjacent nucleotide through covalent bonds Responsible for the formation of hydrogen bonds between complementary DNA bases

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          4
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          The following events occur in the process of DNA replication.

          1. Complementary strands are separated
          2. Free DNA nucleotides pair with complementary nucleotides on each template strand
          3. Hydrogen bonds are formed between complementary bases
          4. Hydrogen bonds are broken between complementary bases
          5. Covalent bonds form between the pentose sugar and the phosphate group of adjacent nucleotides

          Which of the following is the correct order of the events?

          • 1 → 3 → 4 → 2 → 5

          • 3 → 1 → 2 → 4 → 5

          • 2 → 1 → 3 → 4 → 5

          • 4 → 1 → 2 → 3 → 5

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          5
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          The experiments done by Meselson and Stahl in the 1950s provided evidence that DNA replication was semi-conservative.

          They transferred bacteria that contained only 15N in their DNA and transferred them to a medium containing only 14N. They allowed the bacteria to divide twice and then centrifuged the DNA.

          The following diagram shows a few test tubes with results from their investigation.

          7bbtfHYK_h-5

          Which of these test tubes shows the predicted results after two generations in the medium with the light isotope?

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