Lesson 3.8.2.2.1

3.8.2.2.1 Regulation of transcription and epigenetics Quiz: AQA Biology, Unit 8

20 questions

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Lesson 3.8.2.2.1, Regulation of transcription and epigenetics: 20 multiple choice questions for the AQA Biology (7402), Unit 8: The control of gene expression, written with Revision Ninja.

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The 20 questions

  1. In eukaryotes, what must a transcription factor do to stimulate transcription?

    • Leave the cell by exocytosis
    • Be broken down by ribosomes
    • Move from the nucleus into the cytoplasm
    • Move from the cytoplasm into the nucleus
  2. How does oestrogen initiate transcription of target genes?

    • It binds the ribosome directly and stops translation of every mRNA, which in turn switches off transcription of target genes
    • It is converted into mRNA in the cytoplasm, and the mRNA then carries the hormone into the nucleus to act on genes
    • It binds a surface receptor and activates adenylate cyclase, which makes cAMP that then switches genes on in the cytoplasm
    • It passes through the cell membrane, binds a receptor and the complex acts as a transcription factor in the nucleus
  3. Epigenetics is best defined as:

    • Heritable changes in gene function without changes to the base sequence of DNA
    • Changes in the amino acid sequence of a protein caused by a substitution in the gene, which can be inherited by the next generation
    • Changes in the base sequence of DNA caused by mutation, which are passed on to offspring only if the mutation occurs in a gamete
    • Changes to the number of chromosomes in a cell, which occur when chromosomes fail to separate correctly during meiosis or mitosis
  4. Increased methylation of DNA tends to:

    • Stimulate transcription of the affected gene
    • Increase the production of ribosomes
    • Make the DNA more easily copied during replication
    • Inhibit transcription of the affected gene
  5. Decreased acetylation of histones tends to:

    • Increase the production of amino acids
    • Reduce transcription by keeping chromatin more condensed
    • Increase transcription by loosening chromatin
    • Stop DNA replication
  6. Which two changes can environmental factors cause to inhibit transcription epigenetically?

    • Increased acetylation of DNA or decreased methylation of histones
    • Increased mutation rate or decreased repair of DNA
    • Increased splicing or decreased exon production
    • Increased methylation of DNA or decreased acetylation of histones
  7. Epigenetic regulation is particularly relevant to the development and treatment of:

    • Only nutritional deficiencies
    • Only bacterial infections
    • Only changes in blood pressure
    • Disease, especially cancer
  8. A drug inhibits DNA methyltransferase and a tumour suppressor gene had been methylated. What is the most likely effect?

    • Transcription of the tumour suppressor gene stops completely
    • The DNA sequence of the gene is changed by the drug
    • The tumour suppressor gene is deleted from the genome
    • Transcription of the tumour suppressor gene may increase
  9. Gene expression falls in a plant grown in cold conditions, but its DNA sequence is unchanged. What is the most likely explanation?

    • A new mutation has changed the DNA sequence in every cell
    • The plant has lost chromosomes during growth
    • The plant has changed its genotype through meiosis
    • An epigenetic change, such as increased methylation, has reduced transcription
  10. Why does a steroid hormone such as oestrogen not need a receptor on the cell surface?

    • It is digested before it can reach the nucleus
    • It is lipid-soluble and diffuses through the phospholipid bilayer
    • It is a large polypeptide that is carried into the cell by vesicles
    • It is only active outside the cell membrane
  11. Identical twins differ in methylation patterns and in a measured trait. Which conclusion is best supported?

    • Environmental factors can alter gene expression even in genetically identical individuals
    • The twins cannot differ in any trait because they have identical genomes, so the methylation difference must be a measurement error
    • The twins must have different DNA sequences, since methylation differences can only arise from a change in the base order of the DNA
    • The difference proves that genetics has no role in the trait
  12. Gene expression is 40 units in a control and 10 units in a sample with increased methylation. How many times lower is the expression in the sample?

    • Twofold lower
    • Twenty-five per cent lower
    • Thirtyfold lower
    • Fourfold lower
  13. A transcription factor enters the nucleus and binds to the promoter of a target gene. What is the expected effect?

    • The target gene is methylated and silenced
    • The target gene is permanently deleted
    • Translation of the target mRNA is blocked
    • Transcription of the target gene is stimulated
  14. Which effect is caused by increased methylation of a gene?

    • The DNA sequence of the gene changes
    • The gene is silenced and less mRNA is made
    • The gene is duplicated during replication
    • The gene is expressed at a higher rate
  15. Why can epigenetic changes be passed to daughter cells?

    • Epigenetic marks only exist in mature sperm cells
    • Marks on DNA and histones can be copied and maintained through cell divisions
    • Epigenetic marks are always part of the base sequence and are copied with DNA
    • Epigenetic marks are destroyed at each division
  16. Why is epigenetic control considered a possible target for treating cancer?

    • Epigenetic control only works in bacteria and archaea, so it has no relevance to the human diseases that doctors treat
    • Epigenetic control always causes cancer in every tissue, so blocking all methylation in the body would remove every tumour completely
    • Methylation cannot be affected by any drug, so epigenetic marks are fixed for life and cannot be targeted in treatment at all
    • Abnormal methylation can silence tumour suppressor genes, and drugs that reverse methylation might restore their activity
  17. Put these events in the most likely order: 1 transcription factor enters the nucleus, 2 it binds the promoter, 3 transcription increases, 4 more protein is produced. Which sequence is correct?

    • 4, 3, 2, 1
    • 1, 3, 2, 4
    • 1, 2, 3, 4
    • 2, 1, 3, 4
  18. Why does increased DNA methylation usually reduce transcription?

    • Methyl groups add extra codons to the gene sequence that stop translation, so the ribosome terminates early on every mRNA molecule
    • Methyl groups break the DNA into smaller pieces that cannot be read by the enzymes of the cell, so the gene is destroyed during replication
    • Methyl groups bind mRNA molecules in the cytoplasm and destroy them, so the protein made from the gene is lost before it can act
    • Methyl groups can block transcription machinery and attract proteins that compact the chromatin
  19. A graph shows gene expression falling as methylation rises. What conclusion is best supported?

    • Gene expression is independent of methylation
    • Higher methylation is associated with lower expression of that gene
    • Methylation always causes the DNA sequence to change
    • Methylation increases the number of genes in the cell
  20. Why are epigenetic regulatory marks described as reversible?

    • Methyl and acetyl marks can be added or removed by enzymes in response to the environment
    • Epigenetic marks are permanent changes to the base sequence, so they can be removed only by a mutation that alters the DNA itself
    • Epigenetic marks are removed only when the cell dies, so they remain in place for the whole life of every cell in the body
    • Epigenetic marks can only be changed by mutation of the DNA sequence, which means they cannot be altered by the environment or by drugs

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