Identical twins are raised in different households. As adults they have different masses but the same ABO blood group.
Which conclusion is best supported?
Environmental differences may contribute to the difference in mass.
Environmental differences changed their inherited blood-group alleles.
The different masses prove that their inherited alleles differ.
The same blood group proves that all phenotypes are identical.
40 exam-style questions on Edexcel GCSE Biology 3.4 Variation and the Human Genome Project, covering 3.4.1 Causes of variation, 3.4.2 Outcomes of the Human Genome Project, 3.4.3 Genetic variation within a population, and 3.4.4 Effects of genetic mutations on phenotype. Each one has a worked solution and a mark scheme showing where the marks go.