Biology 9700 · AS & A Level · Passage of information from parents to offspring
Passage of information from parents to offspring — practice question
Neurofibromatosis (NF) is a condition inherited genetically in humans in which tumours form on nervous tissue. One symptom, which may appear at about 20 years of age, is loss of sight caused by tumours on the optic nerve.
(a)[3]
If one parent has NF, his or her children have at least a $50\%$ chance of developing the condition, even when the other parent does not have it. Complete the genetic diagram below to show how NF can be passed from parent to child.
(b)[2]
Suggest how a person might develop NF when there is no family history of the condition.
(c)[3]
Suggest how a tumour on the optic nerve could stop nerve impulses from reaching the brain.
Worked solution & mark scheme
This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Correct symbols and key, for example $A$ = NF allele” …