A study of monozygotic (MZ) twins reveals that although both twins carry the gene variant associated with high risk of type 2 diabetes, only one twin actually develops the condition after a lifetime of a high-sugar diet, while the other twin remains healthy due to active lifestyle choices.
Which of the following statements best explains this outcome in terms of the biological approach?
Both twins share the same genotype, but their phenotypes differ because environmental factors influenced gene expression.
The twins have different genotypes because environmental factors mutated their inherited DNA sequence, leading to different phenotypes.
The healthy twin possesses a dominant genotype, whereas the diabetic twin has expressed a recessive phenotype due to diet.
The twins have different phenotypes because monozygotic twins share only 50%50\%50% of their genetic makeup, resulting in different genetic predispositions.
Practise AQA A Level Psychology Biological approach with exam-style questions for A Level Psychology. 48 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
