Question

You are examining offspring (zygotes) of females that may have one or more copies of a recessive mutation in a maternally active segmentation gene. Which of the following zygotes will have a mutant phenotype: (1) A homozygous zygote that came from a heterozygous mother. (2) A heterozygous zygote that came from a heterozygous mother. (3) A heterozygous zygote that came from a homozygous mother. A. Choices 1 and 2. B.. Choices 2 and 3. C. All of these choices. D. Only choice 3.

Answer 1

Answer is only 1st case that is homozygous zygote is the right answer.

Explanation:

In maternal recessive mutation both the alleles are mutant and exhibit mutant phenotype. The mutated alleles are present as homozygous.

From the definition it is concluded that:

first case, homozygous zygote is mutant phenotype

second case, heterozygous zygote not mutant phenotype

in third case, heterozygous zygote not mutant phenotype.