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A2 · Practice questions · Genetic technology in medicine

Treat, test, think it through.

Six original Cambridge-style questions on genetic technology in medicine, from recombinant proteins to the ethics of screening and gene therapy.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Protein, test, therapy, ethics.

01
Explain
[3 marks]

Explain the advantages of treating haemophilia with recombinant factor VIII rather than factor VIII purified from donated blood.

  • No risk of transmitting infections such as HIV or hepatitis that can be present in donated blood. ✓
  • Supply is reliable and can be produced in large quantities, not limited by the number of blood donors. ✓
  • It is human factor VIII, so it is less likely to provoke an immune response; made in mammalian cells, it has the correct sugar groups. ✓
02
Recall
[2 marks]

Explain what is meant by gene editing and name the three types of change it can make.

  • Gene editing is a form of genetic engineering in which DNA is changed at a specific, targeted site in the genome. ✓
  • It can insert, delete or replace DNA (bases) at that site. ✓
03
Explain
[4 marks]

Outline how gene therapy has been used to treat severe combined immunodeficiency (SCID) caused by a lack of adenosine deaminase.

  • Bone marrow stem cells are removed from the patient. ✓
  • A normal allele of the ADA gene is inserted into the cells using a vector, such as a modified (harmless) virus. ✓
  • The modified cells are grown and returned to the patient (after treatment to make room in the bone marrow). ✓
  • They divide and produce lymphocytes that make ADA, so the immune system works; this is somatic therapy, not passed on to offspring. ✓
04
Explain
[3 marks]

Outline the advantages of genetic screening for harmful alleles of BRCA1 and BRCA2.

  • Carriers of harmful alleles have a much higher risk of breast (and ovarian) cancer, so they can be identified before cancer develops. ✓
  • They can have more frequent checks (mammograms / MRI), so any cancer is found early when treatment is more successful. ✓
  • They can choose preventive surgery or medication; relatives can also be tested. ✓
05
Explain
[2 marks]

Suggest why inherited eye diseases were among the first conditions to be treated successfully by gene therapy.

  • The eye is small and easy to reach, so the vector can be injected directly under the retina into the target cells, and only a small dose is needed. ✓
  • The eye is partly protected from the immune system, so the vector is less likely to be destroyed or cause inflammation (and effects can be checked by testing vision). ✓
06
Analysis
[4 marks]

Discuss the social and ethical considerations of offering genetic screening for Huntington's disease to adults with an affected parent.

  • For: a negative result removes uncertainty; a positive result allows planning of future care, careers and finances. ✓
  • For: informed decisions about having children (for example embryo testing). ✓
  • Against: there is no cure, so a positive result may cause severe anxiety or depression; some people prefer not to know. ✓
  • Against: results affect relatives who may not want to know; possible discrimination by insurers or employers and concerns about privacy; counselling is needed before and after testing. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.