A LevelBiologyOCRExam Questions6. Genetics, Evolution & Ecosystems6.3 Manipulating Genomes

Manipulating Genomes (OCR A Level Biology)

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6.3 Manipulating Genomes

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6.3 Manipulating Genomes

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1
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Why has next-generation sequencing (NGS) accelerated scientific development?

1 Entire genomes can now be sequenced
2 NGS is much faster and less costly than older methods of DNA sequencing
3 Portable technologies allow sequencing to be done outside of traditional labs

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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2
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In addition to forensic investigations, what are the other uses of DNA profiling?

1 Comparing evolutionary relationships between organisms
2 Identifying genetic relationships e.g. paternity testing
3 Curing genetic diseases

  • 1, 2 and 3

  • Only 1 and 2

  • Only 2 and 3

  • Only 1

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3
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What is the function of primers in polymerase chain reaction (PCR)?

  • To synthesise DNA

  • To break the hydrogen bonds between DNA strands

  • To bind to a complementary sequence of DNA and initiate replication

  • To work with the buffer solution to maintain an optimum pH

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4
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What is the source of the DNA polymerase used in polymerase chain reaction (PCR)?

  • Thermophilic bacteria

  • Complementary DNA

  • Human blood serum

  • A genetically engineered bacterium

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1
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Which of the following is not a valid concern about the use of genetic modification?

  • that antibiotic resistance genes could transfer to pathogenic bacteria

  • that herbicide resistance genes could be transferred to wild species

  • that certain seeds might not be available for use by poor farmers

  • that the use of human embryos in stem cell production is unethical

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2
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Which of the following statements about gene therapy is not correct?

  • changes resulting from gene therapy cannot be passed on to offspring

  • germ-line gene therapy affects the whole organism

  • gene therapy is a form of genetic engineering

  • somatic cell gene therapy can only affect a limited number of cells

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3
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Which statement correctly describes a difference between somatic and germ line gene therapy?

  • Germ line therapy involves the use of liposomes; somatic therapy involves use of viral vectors.

  • Somatic therapy can target specific tissues in need of treatment, germ line therapy cannot.

  • Somatic therapy is most successful when targeting single gene defects, but germ line therapy can target multiple defects.

  • Long term success is theoretically more likely with somatic cell therapy than germ line therapy.

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4
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If one molecule of DNA goes through 5 PCR cycles in the thermocycler, how many copies of that molecule of DNA will be produced? 

  • 16

  • 6

  • 32

  • 64

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5
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Some scientists were investigating the frequency of an allele responsible for insecticide resistance in a population of flies.

They obtained DNA samples from a representative group in the population and then carried out PCR to amplify the DNA.

Scientists used the same restriction endonuclease on each sample before undertaking PCR, explain why.

  • To separate the DNA template strands

  • To isolate the required gene sequence

  • To produce smaller DNA fragments

  • To allow RNA polymerase to bind to the promotor region

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6
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DNA samples were taken from five individuals and analysed using gel electrophoresis to produce a DNA profile.  The DNA profile shows the results for a single gene.

What conclusions can be made from the profile shown in the image?

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  • There are equal frequencies of two alleles

  • There are 3 different alleles for the gene

  • There are two alleles and the frequency of one allele is about 75%

  • There are three homozygous individuals in the population

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7
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The image below shows the results of DNA sequencing. Which method of sequencing was used to collect these results?

results-of-sanger-sequencing

  • Nanopore technology

  • Pyrosequencing

  • High-throughput sequencing

  • Sanger sequencing

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8
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Gene sequencing has a number of uses.

Which of the following is not a use of gene sequencing?

  • Building phylogenetic trees

  • The polymerase chain reaction

  • Identification of antigens to be used in vaccine production

  • Identifying restriction enzymes for use in genetic engineering

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9
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Which of the following enzymes is not involved in the process of genetic engineering?

  • Restriction endonuclease

  • DNA helicase

  • Ligase

  • Reverse transcriptase

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10
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Which of the following is the correct definition of 'synthetic biology'? 

  • Taking a section of DNA from one organism and inserting it into the genome of an organism from a different species.

  • Altering a person's DNA in order to treat or cure diseases.

  • Redesigning the genome of existing organisms by creating brand new sections of DNA. 

  • Using biological molecules in industry, such as enzymes used in washing powders.

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1
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What is the best explanation for the use of Taq polymerase in PCR?

  • Using a bacterial enzyme avoids the ethical considerations of having to extract human DNA polymerase

  • Taq polymerase has a high number of disulphide bridges, making it thermostable

  • Taq polymerase has a higher affinity for the substrate than other DNA polymerases

  • Taq polymerase has a higher rate of activity at body temperature than human DNA polymerase

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2
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Which additional steps have to be taken when using gel electrophoresis to determine the haemoglobin variants in patients’ proteomes rather than analysing their DNA?

1 Straightening proteins out into negatively-charged ‘rods’
2 Digesting proteins with enzymes to produce smaller fragments
3 Denaturing proteins to break disulphide bridges
4 Using specific buffer solutions to maintain pH for proteins with different R-groups

  • 1, 2 and 3 only

  • 2 and 4 only

  • 1, 3 and 4 only

  • 1 and 3 only

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3
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Which statements about the genome and proteome in a single human cell are correct?

1 The genome is larger than the proteome because each specialised cell only uses a subset of the genes in the genome to perform its function.
2 It is difficult to determine the genome of a cell because some genes are only transcribed at specific points in development, controlled by regulatory genes.
3 The proteome is larger than the genome because alternative splicing produces multiple proteins from each gene.
4 Determining the proteome of a cell is difficult due to the presence of non-coding DNA in the genome

  • 1 only

  • 2 and 3 only

  • 1 and 2 only

  • 3 and 4 only

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4
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Which statements correctly explain why variable number tandem repeats (VNTRs) are useful for genetic fingerprinting?

1 VNTRs occur in non-coding regions of DNA so are not exposed to selection
2 There are restriction endonuclease sites in the middle of VNTRs
3 The number of VNTRs are inherited by offspring from their parents
4 Fluorescent probes with a similar sequence to a VNTR region can be attached to make them visible under UV light

  • 2 only

  • 1 and 3 only

  • 2 and 4 only

  • 1 and 4 only

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5
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The runoff from nitrogen-rich fertiliser applied to farmland creates major ecological problems. Plants such as legumes have symbiotic nitrogen-fixing bacteria which can provide nitrogen naturally, without the need for adding fertiliser. However, these symbionts are not associated with crops such as corn.

Scientists have developed a strain of nitrogen-fixing bacteria that can associate with corn roots. Initially, this bacterium did not supply the corn with nitrogen when the crop needed it, but the scientists managed to alter the strain so that nitrogen was produced at the right times. 

Which of the following provides a possible explanation for how might they have achieved this?

  • Artificial selection for the most corn-friendly and nitrogen-fixing strains of bacteria

  • Using a plasmid vector to insert corn-associating genes into the bacterium from another bacterial species

  • Using a plasmid vector to insert nitrogen-fixing genes into the bacterium from another bacterial species

  • Using synthetic biology to change bacterial genomes so that they can associate with corn roots and produce nitrogen at the right time

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