Which of the following is true of a mutation that produces an allele that is dominant? (A) It would be expected to cause death - HSC - SSCE Biology - Question 7 - 2001 - Paper 1

A dominant allele is one that expresses its effect in the phenotype even when only one copy is present, which occurs in a heterozygous genotype. Thus, a mutation producing a dominant allele will manifest its traits regardless of whether the second allele is dominant or recessive, making it observable in an individual that carries just one copy of the dominant allele.