On the planet Rockon, there is a small island by the name of Krokus. People who

Question

On the planet Rockon, there is a small island by the name of Krokus. People who live on this island are subject to a condition known as Callus Digito, that enables them to musical instruments with greater skill. The phenotype is caused by a single gene with two alleles, A (dominant allele) and a (recessive allele). On this island, the phenotype is expressed in a dominant fashion, with following penetrance values (Table 1):

A. Rana Island, with proportion 0.52.

B. Rana Island, with proportion 0.75.

C. The proportions will be equal for the two islands.

D. Krokus Island, with proportion 0.32.

E. Krokus Island, with proportion 0.64.

Table 1 Krokus Island. . Penetrances of Callus Digito on the Genotype Penetrance Aa 0.9 0.1 A cross of a true-breeding Callus Digito individual and a true-breeding individual (genotype- aa) without the phenotype occurs. Offspring in the F? generation mate to produce F2 offspring. Meanwhile, on a separate island, called Rana, the same phenotype is inherited in a recessive fashion. The penetrance values on this island are given in Table 2: Table 2. Penetrance values for Callus Digito on the Rana Island. Genotype Penetrance 0.9 0.1 0.1 Aa As on Krokus, a cross of a true-breeing Callus Digito person and a true-breeding unaffected individual (genotype aa) occurs. Offspring in the Fi generation mate to produce F2 offspring. If we restrict our attention to Callus Digito individuals from the F2 generations of each island, which island will have a larger proportion of homozygotes (AA)?

Explanation / Answer

In the krokus island, callus digito is transmitted in autosomal dominant pattern. When two heterozygotes with genotypes Aa mate together, the genotypic ratio is 1:2:1 and the phenotypic ratio is 3:1. So, the proportion of offsprings having this trait of interest is 0.67. The penetrance is 0.9. So, the expression of tradition offsprings is,

= 0.67 × 0.9

= 0.64

In Rana island, the proportion of offsprings having the trait of interest is 0.33.

So, the answer for this question is option E (krokus island, with proportion 0.64).

Related Questions

Navigate

• Browse (All)
• Browse O
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.