Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
Tuberous Sclerosis Complex (TSC) is a genetic disorder caused by a dominant allele in the TSC gene, which results in abnormal tissue growth in organs such as the heart, lungs and kidneys. With treatment, children who have TSC can lead fairly normal lives. Around 33% of people with TSC have at least one parent who also has the condition.
(a)[2]
Explain what is meant by the terms dominant and gene.
(b)[3]
A couple want to begin a family. The man does not have TSC, whereas the woman does have TSC. The woman’s father is not affected. Complete the genetic diagram shown below to show the probability that the couple’s first child will have TSC.
(c)[2]
Suggest how a person could develop TSC even when there is no family history of the condition.
Worked solution & mark scheme
This 7-mark question has a full step-by-step worked solution and mark scheme. One marking point: “A dominant allele is expressed whenever it is present” …