Genetic fingerprintingAQA A-Level Biology: Flashcards

Exam questions on Genetic fingerprinting

1. Police find a very small bloodstain at the scene of a burglary. A forensic laboratory produces a genetic fingerprint from the DNA in the stain and compares it with the fingerprint of a suspect. The technique analyses variable number tandem repeats (VNTRs), which are short base sequences repeated one after another in non-coding DNA.
   Explain why two unrelated people are very unlikely to have the same genetic fingerprint.2 marks
2. A baby's father is to be identified. DNA from the mother, the child and two men, X and Y, was amplified by PCR and the VNTR fragments were separated by gel electrophoresis. The fragment sizes, in base pairs, were: mother 900, 650, 420 and 310; child 900, 560, 420 and 280; man X 780, 560, 380 and 280; man Y 700, 480, 310 and 200.
   Use the data to explain which man is the child's father.2 marks
3. A zoo breeding programme for an endangered big cat has a small captive population. Scientists use genetic fingerprinting to analyse VNTRs in each animal. They compared two captive populations, X and Y, each of 30 animals, at six VNTR loci. In population X, 24 of the 30 animals have the same VNTR pattern at all six loci. In population Y, 3 of the 30 animals do.
   Explain why scientists might use genetic fingerprinting in a breeding programme for animals.3 marks