Question

You are studying two traits in zebra fish: (1) skin pigmentation, where there are two patterns: striped and spotted (2) eye color, where there are iridescent and black phenotypes. You mate two flies that are heterozygous for the genes that control both of these traits and get the following phenotypes in the following ratio: 9 striped and iridescent : 3 striped and black : 3 spotted and iridescent : 1 spotted and black Considering these traits, which alleles separated at which stage of meiosis?

Select one: a. Striped segregated from iridescent in meiosis I, and spotted segregated from black in meiosis II.

b. Striped segregated from spotted in meiosis II, and iridescent segregated from black in meiosis II.

c. Striped segregated from spotted in meiosis I, and iridescent segregated from black in meiosis I.

d. Striped segregated from spotted in meiosis I, and iridescent segregated from black in meiosis II.

e. Striped segregated from spotted in meiosis II, and iridescent segregated from black in meiosis I.

Answer 1

During Anaphase-I of meiosis-I non-sister chromatids of homologous chromosomes are segregated. Non-sister chromatids move to the opposite pole during anaphase-I. 9:3:3:1 ratio is shown by the genes that are present on different chromosomes. Since genes for skin pigmentation and eye color are present on different chromosomes so they will be segregated during meiosis-I. After meiosis-I each daughter cell has two copies each chromatid..

During Meiosis-II, chromatids are separated thus leads to formation of haploid gametes.

So the correct answer is c. Striped segregated from spotted in meiosis I, and iridescent segregated from black in meiosis I and rest options are wrong.