IBBiology: HLDPTopic Questions7. Nucleic Acids (HL Only)7.2 Transcription & Gene Expression

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First teaching 2014

Last exams 2024

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Transcription & Gene Expression (DP IB Biology: HL)

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7.2 Transcription & Gene Expression

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7.2 Transcription & Gene Expression

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1
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Which of the following provides the most accurate definition of a promoter?

  • DNA sequences that code for the production of polypeptides

  • DNA sequences that produce RNA molecules

  • DNA sequences that act as a binding site for RNA polymerase during transcription

  • DNA sequences that codes for the production of enzymes

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2
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Which of the following is not an example of how the external environment can influence gene expression?

  • Fur colouration of Siamese cats

  • Petal colour of snapdragons

  • Skin colouration after sun exposure

  • Sea turtle eggs hatching as females if incubated at 30°C

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3
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Which of the following are examples of groups that could be added to the tails of histones to chemically modify them?

  1. Acetyl
  2. Hydroxyl
  3. Phosphate
  4. Amino

  • I. and III. only

  • II. and IV. only

  • I., II. and III.

  • II., III. and IV.

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4
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Which of the following correctly compares the modification of RNA in prokaryotes and eukaryotes?

  Prokaryotes Eukaryotes
A. mRNA can be spliced to remove non-coding sequences A methylated cap can be added to the 5' end of the mRNA molecule
B. A poly-A tail is added to the 3' end of the mRNA molecule mRNA does not require modification after transcription
C. mRNA does not require modification after transcription mRNA can be spliced to remove non-coding sequences
D. mRNA can be spliced to remove non-coding sequences A poly-A tail is added to the 3' end of the mRNA molecule

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    5
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    Which of the following best describes the importance of regulating gene expression?

    • To ensure that essential genes are expressed all the time in the relevant cells

    • To ensure that only the relevant genes in the relevant cells are expressed at certain times

    • To ensure that only the relevant genes are expressed in the relevant cells at all times

    • To ensure that the same group of essential genes is expressed in all cells of the organism at certain times

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    11 mark

    Which of the following statements describes the promoter?

    I.

    The first part of a gene to be transcribed.

    II.

    Acts as a binding site for RNA polymerase.

    III.

    A non-coding sequence located near the gene.

    IV.

     Only found in eukaryotes.

    • I and II

    • I and III

    • II and III

    • All the above

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    21 mark

    In humans, during periods of hypoxia (low oxygen in tissues) the transcription factor HIF (Hypoxia-Inducible Factor) binds to the Hypoxia Response Element (HRE) sequence and increases transcription of the EPO gene. This stimulates the production of red blood cells. The diagram shows the EPO gene and regulatory elements.                                                                                   q2_7-2_transcription_gene_expression_ib_biology_hl_mcq

    Which kind of regulatory elements are HIF and HRE?

      HIF HRE
    A

    Activator protein

    Enhancer sequence
    B

    Repressor protein

    Silencer sequence
    C

    Enhancer sequence

    Activator protein
    D

    General transcription factor

    Enhancer sequence

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      31 mark

      Which of the following occur in the bacterium Escherichia coli if no lactose is present?

      • LAC repressor protein is deactivated.

      • Lactose binds to the LAC repressor protein preventing it from binding near the promoter.

      • Gene that codes for the LAC repressor protein is silenced.

      • LAC repressor protein binds near the promoter blocking RNA polymerase from transcribing genes involved in lactose metabolism.

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      41 mark

      Identical twins have the same DNA (genotype) but often display many observable physical differences (phenotype). Studies on twins have shown that one twin can be more susceptible to diseases like cancer or diabetes.

      Which of the following statements best explains these differences between identical twins?

      • One twin is more prone to random mutations of DNA.

      • Epigenetic changes can affect the structure of proteins.

      • One twin inherited epigenetic modifications from a parent.

      • An organism's environment can influence gene expression patterns.

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      51 mark

      The diagram below shows a nucleosome where the histone tails have had an acetyl group added.q5_7-2_transcription_gene_expression_ib_biology_hl_mcq

      Which statement best describes the effect of acetylation of histone tails?

      • Adding an acetyl group causes the DNA to be less tightly wrapped

      • Adding an acetyl group deactivates the gene

      • Adding an acetyl group causes the DNA to be more tightly wrapped

      • Adding an acetyl group helps maintain a positive charge

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      61 mark

      The simplified diagram below shows a section of DNA where a methyl (-CH3) group has been added to a cytosine base.q6_7-2_transcription_gene_expression_ib_biology_hl_mcq   

      Which of the following best describes the outcome of direct methylation of DNA?

      • It stimulates the expression of the gene.

      • It prevents guanine from forming hydrogen bonds.

      • It inhibits the binding of transcription factors.

      • It causes breaks in the phosphate deoxyribose backbone.

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      71 mark

      Which of the following statements about transcription are correct?

      I.

      RNA polymerase synthesises mRNA in a 5’ to 3’ direction.

      II.

      RNA polymerase binds near the promoter.

      III.

      RNA polymerase uses the sense strand of DNA as a template.

      IV.

      RNA polymerase synthesises mRNA in a 3’ to 5’ direction.

      • I only

      • I and II

      • I, II and III

      • II, III and IV

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      81 mark

      It is estimated that the human genome contains between 20 000 and 25 000 genes. However, the proteome is estimated to contain up to 400 000 proteins. This large difference in numbers is due to alternative splicing.

      Which of the following best describes alternative splicing in eukaryotes?

      • Different combinations of introns can be incorporated into the mature mRNA. 

      • Some exons are duplicated. 

      • Different combinations of exons can be incorporated into the mature mRNA. 

      • Different genes can be fused together.

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      91 mark

      Which of the following accurately describes the sequence of steps that happen following production of a pre-mRNA in eukaryotes?

      A

      Addition of a 5’ methylated cap

      Removal of a 3’ poly-A tail

      Removal of non-coding sequences

      Transport to the cytoplasm

      B

      Binding of RNA polymerase

      Addition of a 5’ methylated cap

      Removal of non-coding sequences

      Transport to the cytoplasm

      C

      Addition of a 5’ methylated cap

      Addition of a 3’ poly-A tail

      Transport to the cytoplasm

      Binding to ribosome

      D

      Addition of a 5’ methylated cap

      Addition of a 3’ poly-A tail

      Removal of non-coding sequences

      Transport to the cytoplasm

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        101 mark

        Which of the following statements about DNA methylation are correct?

        I.

        DNA methylation varies throughout a lifetime.

        II.

        DNA methylation can be affected by environmental factors.

        III.

        Analysis of DNA methylation patterns can be used in the early detection of disease.

        IV.

        DNA methylation can cause changes in the DNA sequence.

        • I only

        • I and II

        • I, II and III

        • All the above

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        1
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        The reaction of bacteria to DNA damage is called the SOS response. During this response, the cell cycle stops and a DNA damage repair system is induced. Two main proteins are involved, namely LexA and RecA. In normal cells, the LexA protein is bound to a section of prokaryotic DNA called the SOS box, which codes for various genes involved with DNA repair. In cells with DNA damage, RecA will bind to and cleave the LexA protein.

        Which of the following correctly identifies each of the components of the SOS response?

          LexA RecA SOS box
        A. Repressor protein Activator protein Transcription factor
        B. Activator protein Repressor protein Promoter
        C. Repressor protein Activator protein Promoter
        D. Activator protein Repressor protein Silencer sequence

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          2
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          Which of the following applies to both mutations and epigenetics?

          1. It may affect the visible characteristics of an organism
          2. The DNA base sequence can change and impact the expression of genes
          3. Environmental factors may play an important role in the development of changes
          4. Modifications may be passed on to the next generation at a cellular level
          5. The amino acid tails of histones are modified by methylation, acetylation and phosphorylation

          • I, IV and V.

          • I, III and IV.

          • II, III and IV.

          • I, III, IV and V.

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          3
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          Female embryos contain two copies of the X chromosome, even though they initially do not need both copies to be active. In order to avoid producing double the amount of polypeptides required, the paternal X chromosome is inactivated during the first few divisions after fertilisation. This is done by the methylation of lysine on different histones.

          Which of the following provides the most accurate explanation of how this would inactivate the paternal X chromosome?

          • Adding a methyl group to lysine will maintain the negative charge to allow chromatin to become more condensed and inhibit transcription of the genes.

          • Adding a methyl group to lysine will maintain the positive charge to allow chromatin to become less condensed and inhibit transcription of the genes.

          • Adding a methyl group to lysine will maintain the positive charge to allow chromatin to become more condensed and promote transcription of the genes.

          • Adding a methyl group to lysine will maintain the positive charge to allow chromatin to become more condensed and inhibit the transcription of the genes.

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          4
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          The muscle protein titin is an important component of cardiac muscle tissue. Several forms of titin exist, even though it is coded for by the same gene. During the development of the foetal heart, titin exists in the form of long, springy protein strands, while in the adult heart titin is much shorter.

          Which of the following provides the most plausible explanation for the occurrence of the different forms of titin?

          • Different post-transcriptional changes are made to the pre-mRNA of the titin gene, resulting in different mature mRNA molecules that can be translated into different polypeptides.

          • Different exons of the gene coding for titin are spliced to form different mature mRNA molecules that can be translated into different polypeptides.

          • Different introns of the gene coding for titin are joined together to form different mature mRNA molecules that can be translated into different polypeptides.

          • Different poly-A tails are added to the 3' end of pre-mRNA molecules, resulting in different mature mRNA molecules that can be translated into different polypeptides.

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          5
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          Which of the following provides a reason why prokaryotic mRNA does not require post-transcriptional modification?

          1. Prokaryotic DNA is a circular, double-stranded molecule, therefore mRNA molecules are less complex than in eukaryotes.
          2. A lack of a nuclear membrane means that transcription and translation can be coupled together.
          3. Prokaryotic DNA lacks introns, which means that no splicing needs to occur.
          4. Prokaryotes have smaller, 70S ribosomes.
          5. RNA polymerase in prokaryotes will transcribe a single strand of mRNA.

          • I and V only.

          • II, III and IV.

          • II and III only.

          • I, II and V.

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