CIE A Level Biology
CIE A Level Biology Topic 19: Genetic Technology Exam Questions
Free CIE A Level Biology exam questions for Topic 19: Genetic Technology, with a mark scheme for every pack. Covers recombinant DNA, restriction enzymes, plasmid vectors, PCR, gel electrophoresis, microarrays, bioinformatics, gene therapy, genetic screening and GM organisms.
Topic 19: Genetic Technology exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About CIE A Level Biology Topic 19: Genetic Technology
Genetic technology is the final topic in the Cambridge 9700 syllabus and draws on DNA structure, protein synthesis and inheritance. You need to describe the tools used to make recombinant DNA: restriction enzymes, DNA ligase, plasmids, reverse transcriptase and promoters, with marker genes such as those for fluorescent proteins. Techniques include the polymerase chain reaction, gel electrophoresis, microarrays and bioinformatics. Applications include human insulin production in bacteria, genetic screening and diagnosis, gene therapy and the use of genetically modified crops such as herbicide-resistant or insect-resistant plants. Questions often ask you to explain each stage of a technique or to discuss the social and ethical issues involved.
What you need to know
- Recombinant DNA tools Restriction enzymes cut DNA at specific sequences, often leaving sticky ends. DNA ligase joins sugar-phosphate backbones. Reverse transcriptase makes cDNA from mRNA, avoiding introns.
- Vectors and markers Plasmids carry genes into bacteria and need a promoter for expression. Marker genes such as those for green fluorescent protein or antibiotic resistance identify transformed cells.
- PCR PCR amplifies DNA: denature at about 95 C, anneal primers at about 55 to 65 C, and extend with Taq polymerase at about 72 C. Each cycle doubles the number of copies.
- Gel electrophoresis DNA fragments are negatively charged and move towards the anode through agarose gel; smaller fragments move further. Used in DNA profiling and diagnosis.
- Microarrays and bioinformatics Microarrays detect which genes are present or being expressed by hybridisation with labelled DNA. Bioinformatics uses databases and software to compare sequences.
- Applications Bacteria make human insulin; genetic screening detects alleles such as those for breast cancer (BRCA) or cystic fibrosis; gene therapy inserts functional alleles using viral or liposome vectors; GM crops include herbicide-resistant and insect-resistant varieties.
Common mistakes in Topic 19: Genetic Technology
- Saying restriction enzymes cut DNA anywhere; they cut at specific recognition sequences.
- Writing that DNA moves towards the cathode in electrophoresis; it moves to the positive anode because of its phosphate groups.
- Forgetting why Taq polymerase is used: it is thermostable and is not denatured at 95 C.
- Confusing gene therapy with genetic screening; screening identifies alleles, gene therapy adds functional alleles.
- Assuming inserted genes are always expressed; a suitable promoter is required.
Try three Topic 19: Genetic Technology exam-style questions
1. A PCR starts with 5 molecules of DNA. Calculate the number of molecules after 12 cycles. (2 marks)
Show the mark scheme answer
5 x 2^12; = 5 x 4096 = 20 480.
2. Explain why reverse transcriptase is used to make the human insulin gene for insertion into bacteria. (3 marks)
Show the mark scheme answer
mRNA for insulin is extracted from pancreatic beta cells; reverse transcriptase makes cDNA from mRNA; cDNA has no introns, which bacteria cannot remove.
3. Describe how gel electrophoresis separates DNA fragments. (3 marks)
Show the mark scheme answer
DNA is placed in wells in agarose gel and a current is applied; DNA is negatively charged so moves towards the anode; smaller fragments move faster and further through the gel.
Topic 19: Genetic Technology FAQs
What does Cambridge International A Level Biology Topic 19 Genetic technology cover?
It covers recombinant DNA tools, PCR, gel electrophoresis, microarrays, bioinformatics, and applications in medicine and agriculture, including gene therapy, screening and GM crops.
Which paper is Genetic technology examined in?
It is A Level content, assessed mainly in Paper 4 (A Level structured questions). Paper 5 (planning, analysis and evaluation) can also use contexts from this topic.
How should I answer ethics questions on genetic technology?
Give balanced points with biological reasoning, such as benefits for food security or treatment against risks of gene flow, reduced biodiversity, cost and consent.
