A-Level Biology Topic 19: Genetic Technology MCQs – 30 Practice Questions with Answers (Cambridge 9700)
Free practice for Cambridge A-Level Biology 9700 on genetic technology, with every question followed by a short explanation to help you check your understanding.
Principles of Genetic Technology
Q1. What is recombinant DNA?
- (A) DNA that has been copied exactly with no change
- (B) DNA formed by joining a gene from one source into DNA from another source, such as a vector
- (C) DNA that has been broken down into single nucleotides under the conditions described, for the population in this investigation
- (D) DNA that contains no genes at all
Show Answer
Answer: B – Recombinant DNA is DNA made by combining genetic material from different sources, for example a donor gene inserted into a plasmid.
Q2. What is genetic engineering?
- (A) Waiting for random mutations to change a species
- (B) Selecting parents by appearance over many generations
- (C) Studying the inheritance of traits without changing DNA
- (D) The deliberate manipulation of genetic material to modify specific characteristics, which may involve transferring a gene so that it is expressed
Show Answer
Answer: D – Genetic engineering deliberately changes genetic material to modify a characteristic, often by transferring a gene into an organism where it is expressed.
Q3. Which is one way in which a gene to be transferred can be obtained?
- (A) It can be extracted from the DNA of a donor organism
- (B) It can only be taken from a virus, never from another organism
- (C) It must always be copied from a protein, not from DNA
- (D) It can only be found by chance in a soil sample
Show Answer
Answer: A – A gene for transfer may be extracted directly from the DNA of a donor organism.
Q4. A gene is synthesised from the mRNA of a donor organism. Which enzyme is needed to make a DNA copy from that mRNA?
- (A) DNA ligase, which joins DNA fragments
- (B) A restriction endonuclease, which cuts DNA for the organisms and the conditions described in this investigation
- (C) Reverse transcriptase, which synthesises DNA from an RNA template
- (D) Taq polymerase, which works only in PCR
Show Answer
Answer: C – Reverse transcriptase builds a DNA copy from an mRNA template, so a gene can be synthesised from donor mRNA.
Q5. How can a gene be obtained when no donor DNA or mRNA is available?
- (A) By waiting for the gene to appear by mutation
- (B) By synthesising it chemically from nucleotides, using a known base sequence
- (C) By copying it from the protein it codes for
- (D) By removing it from an unrelated species by force for the organisms and the conditions described in this investigation
Show Answer
Answer: B – Genes can also be synthesised chemically from nucleotides when their base sequence is known.
Q6. What is the role of a restriction endonuclease in gene transfer?
- (A) It cuts DNA at specific base sequences, producing fragments that can be joined to other DNA
- (B) It seals gaps between DNA fragments
- (C) It carries a gene into a host cell as a vector for the organisms and the conditions described in this investigation
- (D) It translates mRNA into a protein product
Show Answer
Answer: A – Restriction endonucleases cut DNA at specific recognition sequences, allowing a gene and a vector cut with the same enzyme to be joined.
Q7. What is the role of DNA ligase in gene transfer?
- (A) It cuts a plasmid open at one site
- (B) It copies mRNA into DNA
- (C) It separates DNA strands by heating in the population studied, under the conditions described for this investigation
- (D) It joins DNA fragments together, sealing the sugar-phosphate backbone
Show Answer
Answer: D – DNA ligase joins the gene into the vector by forming phosphodiester bonds between adjacent nucleotides.
Q8. What is the role of a plasmid in gene transfer?
- (A) It destroys foreign DNA in the host cell
- (B) It translates the transferred gene into protein in the population studied, under the conditions described for this investigation
- (C) It acts as a vector, carrying the gene into a host cell where it can be replicated and expressed
- (D) It prevents the host cell from dividing
Show Answer
Answer: C – Plasmids are used as vectors to carry a desired gene into host cells.
Q9. What does DNA polymerase do?
- (A) It cuts DNA at specific sequences
- (B) It synthesises a new DNA strand by adding nucleotides complementary to a template strand
- (C) It joins separate DNA fragments after cutting under the conditions described, for the population in this investigation
- (D) It breaks down mRNA after translation
Show Answer
Answer: B – DNA polymerase builds new DNA by adding nucleotides complementary to a template strand.
Q10. Why may a promoter have to be transferred into an organism as well as the desired gene?
- (A) To make the gene larger and easier to see
- (B) To protect the gene from restriction enzymes
- (C) To stop the gene from being copied
- (D) So that the gene is transcribed and expressed in the recipient, because the recipient may lack a suitable promoter for it
Show Answer
Answer: D – A gene needs a promoter to start transcription, so a suitable promoter may have to be transferred with it for the gene to be expressed.
PCR, Electrophoresis and Genome Analysis
Q11. How can gene expression be confirmed after gene transfer, using a marker gene?
- (A) By checking whether the host cell has died
- (B) By using a marker gene coding for a fluorescent product, whose presence shows the transferred DNA is being expressed
- (C) By counting the total number of host cells
- (D) By measuring the size of the host cell only
Show Answer
Answer: B – A marker gene coding for a fluorescent product confirms expression, because fluorescence appears only if the gene is switched on.
Q12. What is gene editing?
- (A) Selecting parents with desired traits over generations in the sample studied, across the range of conditions described here
- (B) Copying a whole genome without changing it
- (C) The insertion, deletion or replacement of DNA at specific sites in the genome
- (D) The random shuffling of chromosomes during meiosis
Show Answer
Answer: C – Gene editing is a form of genetic engineering involving targeted insertion, deletion or replacement of DNA.
Q13. In PCR, what happens during the denaturation step?
- (A) The double-stranded DNA is heated so that the two strands separate
- (B) Primers bind to their complementary sequences for the organisms and the conditions described in this investigation
- (C) Taq polymerase builds new DNA strands
- (D) DNA fragments are separated on a gel
Show Answer
Answer: A – Heating denatures the DNA, breaking the hydrogen bonds between strands so that each strand can act as a template.
Q14. In PCR, what happens during the annealing step?
- (A) The DNA strands are heated apart
- (B) New DNA strands are completed
- (C) The reaction mixture is cooled to stop the reaction for the organisms and the conditions described in this investigation
- (D) Short primers bind to complementary base sequences on the template strands
Show Answer
Answer: D – During annealing, primers attach to complementary sequences on the separated template strands, marking where copying starts.
Q15. Why is Taq polymerase used in PCR, rather than an ordinary DNA polymerase?
- (A) It works only at very low temperatures
- (B) It cuts DNA at specific sites
- (C) It is thermostable, so it survives the high temperature of denaturation and can keep working through repeated cycles
- (D) It joins DNA fragments without using nucleotides
Show Answer
Answer: C – Taq polymerase is heat stable, so it is not denatured during the heating step of each PCR cycle.
Q16. A PCR reaction starts with one DNA molecule. After three complete cycles, how many molecules are present, assuming perfect doubling each cycle?
- (A) 3
- (B) 8
- (C) 6
- (D) 16
Show Answer
Answer: B – PCR amplifies DNA exponentially: 1 becomes 2, then 4, then 8 molecules after three cycles.
Q17. In gel electrophoresis, why do DNA fragments move through the gel?
- (A) DNA is negatively charged, so it moves towards the positive electrode, with smaller fragments moving further
- (B) DNA is positively charged, so it moves towards the negative electrode in the population studied, under the conditions described for this investigation
- (C) DNA is uncharged and is carried by water flow alone
- (D) DNA fragments move only because the gel is heated
Show Answer
Answer: A – DNA carries a negative charge, so it migrates towards the positive electrode, and smaller fragments travel further through the gel in a given time.
Q18. What is gel electrophoresis used for?
- (A) To sequence every base in a genome in one step in the sample studied, across the range of conditions described here
- (B) To translate DNA into protein
- (C) To copy DNA into many identical molecules
- (D) To separate DNA fragments of different lengths, giving a pattern that can be compared
Show Answer
Answer: D – Gel electrophoresis separates DNA fragments by length, so samples can be compared by their band patterns.
Q19. How are microarrays used in studies of gene expression?
- (A) To cut DNA with restriction enzymes
- (B) To amplify a single DNA fragment by PCR in the population studied, under the conditions described for this investigation
- (C) To detect mRNA from many genes at once, showing which genes are being expressed
- (D) To transfer genes into host cells
Show Answer
Answer: C – Microarrays can detect mRNA from many genes, revealing patterns of gene expression, and they are also used in genome analysis.
Q20. What is a benefit of databases holding nucleotide sequences of genes and genomes, and amino acid sequences of proteins?
- (A) They replace the need for any laboratory work
- (B) They allow sequences to be compared and searched, helping to identify genes, compare species and study protein structure and function
- (C) They store only the sequences of one species
- (D) They prevent anyone else from studying a gene
Show Answer
Answer: B – Sequence databases let researchers compare genes and proteins, identify unknown sequences and investigate structure and function.
Medicine, Agriculture and Ethics
Q21. What is an advantage of using recombinant human insulin to treat diabetes, rather than insulin from animals?
- (A) It is identical to human insulin, can be made in large amounts, and is less likely to cause an immune reaction than animal insulin
- (B) It works without any need for regular doses
- (C) It cures diabetes permanently after one dose
- (D) It is produced by the patient’s own pancreas
Show Answer
Answer: A – Recombinant human insulin matches the human protein, is available in large supply and reduces the risk of immune reactions seen with animal insulin.
Q22. Recombinant adenosine deaminase is used to treat a deficiency of that enzyme. What does the treatment supply?
- (A) A cure for diabetes
- (B) A treatment for breast cancer
- (C) A replacement for haemoglobin in red blood cells
- (D) The missing enzyme itself, in human form, to replace the enzyme the patient cannot make in sufficient amounts
Show Answer
Answer: D – Recombinant adenosine deaminase provides the human enzyme that is deficient, just as recombinant factor VIII provides the clotting factor missing in haemophilia.
Q23. What is an advantage of genetic screening for BRCA1 and BRCA2?
- (A) It guarantees that breast cancer will never develop in the population studied, under the conditions described for this investigation
- (B) It replaces the need for any medical check-ups
- (C) It identifies people at increased risk, allowing closer monitoring and informed decisions about prevention
- (D) It treats breast cancer directly
Show Answer
Answer: C – Screening for BRCA1 and BRCA2 shows increased risk, not certainty, and allows earlier monitoring and informed choices.
Q24. What can genetic screening for Huntington’s disease offer a person with a family history of the condition?
- (A) A cure for the disease if the gene is found
- (B) Knowledge of whether they carry the gene, allowing informed life and family decisions, even though there is no cure
- (C) A guarantee that their children will not inherit it
- (D) A treatment that removes the gene from all their cells
Show Answer
Answer: B – Screening can show whether a person carries the Huntington’s gene, informing personal and family decisions, although it does not provide a cure.
Q25. What is an advantage of genetic screening for cystic fibrosis?
- (A) It identifies carriers and affected individuals early, allowing earlier treatment planning and informed family decisions
- (B) It cures cystic fibrosis in the person screened
- (C) It guarantees that no child will be born with the condition
- (D) It replaces the need for any other medical test
Show Answer
Answer: A – Early identification of carriers and affected people allows treatment to be planned sooner and families to make informed decisions.
Q26. How is gene therapy used to treat severe combined immunodeficiency (SCID)?
- (A) By removing the patient’s immune system completely
- (B) By giving the patient antibiotics for life
- (C) By screening relatives for the faulty gene
- (D) By introducing a functional copy of the faulty gene into the patient’s cells, so the missing protein can be made
Show Answer
Answer: D – In gene therapy for SCID, a working copy of the gene is delivered to the patient’s cells so that the missing protein is produced.
Q27. How is gene therapy applied to inherited eye diseases?
- (A) By replacing the whole eye with a donor eye
- (B) By giving the patient a new pair of glasses
- (C) By delivering a functional copy of the faulty gene to retinal cells, so those cells can make the missing protein
- (D) By removing the faulty gene from every cell in the body under the conditions described, for the population in this investigation
Show Answer
Answer: C – Gene therapy for inherited eye diseases delivers a working gene copy to cells in the retina, restoring production of the needed protein.
Q28. Which is a genuine social or ethical consideration raised by genetic screening?
- (A) The cost of the test, which is always zero
- (B) Concerns about privacy, possible discrimination, psychological impact, and who should have access to the results
- (C) The fact that screening always gives a certain prediction in the sample studied, across the range of conditions described here
- (D) The fact that screening treats the disease it tests for
Show Answer
Answer: B – Screening raises questions about privacy, discrimination, anxiety from results, consent and fair access, and gene therapy raises similar social and ethical questions.
Q29. Why is genetically modified salmon used as an example of genetic engineering in agriculture?
- (A) It grows faster and reaches market size sooner, improving productivity to help meet demand for food
- (B) It needs no food at all while growing
- (C) It can live in any water without oxygen
- (D) It produces its own antibiotics permanently in the population studied, under the conditions described for this investigation
Show Answer
Answer: A – GM salmon grow more quickly, so they reach market size sooner, illustrating how genetic engineering can improve the productivity of farmed animals.
Q30. Which pair correctly matches the genetically modified crops in the syllabus examples?
- (A) Soybean resistant to insects and cotton resistant to herbicides
- (B) Soybean resistant to drought and cotton resistant to frost
- (C) Soybean that fixes its own nitrogen and cotton that needs no water
- (D) Soybean resistant to herbicides and cotton resistant to insects
Show Answer
Answer: D – The syllabus examples are herbicide resistance in soybean and insect resistance in cotton, both aimed at improving crop quality and productivity.
Work through any questions you missed again, then revise those areas before moving on to the next topic.