Cambridge International A Level Biology Revision Guide

Cambridge International A Level Biology
6 a Genetic fingerprinting reveals the differences in variable number tandem repeats (VNTRs) in the DNA of
different individuals. Explain what is meant by a VNTR. [3]
b Examine the figure, which shows diagrammatic DNA profiles of a mother, her child and a possible father of the child.
Decide, giving your reasons, whether the possible father is the biological father of the child. [3]
[Total: 6]
control
DNA
mother child possible
father
488
7 a Explain what is meant by:
i gene therapy [1]
ii genetic screening. [1]
b Explain why it is easier to devise a gene therapy for a condition caused by a recessive allele than for one caused
by a dominant allele. [5]
[Total: 7]
8 a Draw a genetic diagram to show how two heterozygous parents may produce a child with cystic fibrosis.
Use the symbols A/a in your diagram. [3]
b State the probability of one of the children of these parents suffering from cystic fibrosis. [1]
[Total: 4]