Epistasis is when

  1. genes are on the same chromosome
  2. one gene affects the expression of another gene at a different locus
  3. a gene is on the X chromosome
  4. two alleles are both expressed
Answer

B) one gene affects the expression of another gene at a different locus

Gene interaction. AS & A Level Biology · Topic 16 Inheritance · 16.2 The roles of genes in determining the phenotype

Biology MCQ · More A Level Biology: Inheritance MCQs · Practise