Question

Flowers need only 20% of the enzyme produced in wild type to have pink color. A mutant allele is recessive to wild type because the heterozygotes have enough enzyme for pink color flowers. A double mutant does not make enough enzyme for pink flower color and results in a white flower color. Biochemical tests show no activity at all of the mutant enzyme and the enzyme is missing its active site. What type of mutation is this?

		hypermorphic mutation
		hypomorphic mutation
		neomorphic mutation
		null mutation

Answer 1

The answer will be null mutation (Last option).

Explanation: Hypermorphic mutation is a gain-of-function mutation in which normal gene function increased. If this type of mutation occurred then we will observed increase activity of the enzyme. In hypomorphic mutation, wild type gene activity occurred at reduced level. In neomorphic mutation, a novel molecular function is gained. So, we can ignore first three options. In null mutation, wild type enzyme activity is not observed as enzyme become non-functional. Thus, correct answer will be last option.