Q21 · Practice questionSimple familiar1 mark
QUESTION 21
A coding sequence changes the mRNA codon UAU to UAA. Use the supplied genetic code excerpt. The mutation is
(A)
silent
(B)
a frameshift
(C)
nonsense
(D)
missense
WORKED SOLUTION
1 markAnswer C
Answer
C
Working
UAU codes for tyrosine; UAA is a stop codon. The substitution introduces a premature stop, so it is a nonsense mutation.
Marking criteria
- Select C. [1 mark]
Practice question aligned to the current QCAA syllabus; review the worked solution and marking criteria.
View the QCAA syllabus