2021HSCShort answer

Q24 (a)

3 marks

Question

An incidence of an autosomal dominant trait is shown in the pedigree.
Is this trait likely to be the result of a somatic or a germ-line mutation? Justify your answer.

Try the question before revealing the answer.

Solution

Sample answer: It is a somatic mutation because it is a dominant trait but not present in the parents or the offspring of the affected male. If it were a germ-line mutation which occurs in the cells that form gametes, it is most likely it would be seen in the offspring.

3 Marks:

Identifies the type of mutation
Justifies the type of mutation with reference to the information provided

Supplied marking guidance · human reviewed

Compare this with your working, not only your final sentence.

Syllabus alignment

Module 5 · HeredityModule 6 · Genetic Change

Genetic VariationInterpret inheritance patterns, pedigrees and Punnett squares to model genotype combinations.
MutationDistinguish somatic and germ-line mutations and their effects on organisms.

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