Genetic screening and ethical issuesEdexcel A-Level Biology A: Flashcards

Exam questions on Genetic screening and ethical issues

1. A couple who are both carriers of the cystic fibrosis (CF) allele are having fertility treatment. Eight embryos have been created outside the body. When each embryo reaches the eight-cell stage, one cell is removed and its DNA is tested for the CF allele. Only embryos that do not have CF will be placed in the woman's uterus.
   Explain why removing one cell at the eight-cell stage is unlikely to harm the development of the embryo.2 marks
2. A woman who already has a child with a serious recessive disorder is 12 weeks pregnant. She and her partner are both carriers. She has been offered either chorionic villus sampling (CVS) now, or amniocentesis at 16 weeks. Each procedure carries a risk of miscarriage of about 1%.
   Suggest two reasons why the woman might decide not to have either test.2 marks
3. A region has a high frequency of a serious recessive blood disorder. The local health authority offers free carrier screening to all adults who plan to have children. A cheek swab is taken and the DNA is tested for the faulty allele. People found to be carriers are offered genetic counselling.
   Explain how carrier screening and genetic counselling help couples to make informed decisions about having children.3 marks