CAIE IGCSE Biology 18.1.6 Mutation as Genetic Change

Practise defining mutation as genetic change and recognising changes to DNA base sequence in unfamiliar contexts.

Exam points

define a mutation as a genetic change
identify a change in DNA base sequence as a mutation at molecular level
recognise ionising radiation, certain chemicals and some viruses as mutagenic factors

[Maximum number: 2]

Colour blindness is a characteristic that is inherited. Colour blindness is more common in males than in females.

Fig. 6.1 is a pedigree diagram showing the inheritance of colour blindness in a family.

Fig. 6.1

There was no history of colour blindness in the parents and grandparents of individuals 1 and 2.

Suggest how colour blindness first occurred in the family in Fig. 6.1.

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18.1.6—Mutation as genetic change question 1