Read the passage below and answer the questions that follow.
Transgenic Sheep The microinjection of human genetic material into fertilized animal eggs allows the production of transgenic livestock. Sheep eggs are fertilized in vitro and a human gene is microinjected into the pronucleus. These eggs develop into early-stage embryos, which are then surgically transferred into the uterus of surrogate mothers.
A transgenic sheep named Silvia was successfully created to express human clotting factor IX in her milk. Clotting factor IX is a protein that prevents bleeding in patients with haemophilia B. When she matured, Silvia was bred with a normal, non-transgenic ram. She gave birth to a total of 15 offspring, of which 9 successfully inherited the transgene and the ability to produce factor IX in their milk.
Explain what is meant by the term gene.
In which part of the surrogate mother are the embryos implanted?
What percentage of the offspring from Silvia's progeny were confirmed to inherit the transgene?
30 exam-style questions on Edexcel IGCSE Biology Genetic modification (genetic engineering). Each one has a worked solution and a mark scheme showing where the marks go.