参考答案:
Any six of these points for 6 marks:
The skin colour phenotype is an example of polygenic inheritance.
Polygenic traits are the result of the interaction of several genes/alleles.
Each gene contributes to the phenotype.
The phenotype/skin colour shows continuous variation.
Environmental factors can alter gene expression.
Alteration of gene expression produces further variation.
For example, UV light can activate melanin producing genes.
A greater amount of melanin production gives a darker skin tone.
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