Question

n German cockroaches, bulging eyes (bu) are recessive to normal eyes (bu+) and curved wings (cv) are recessive to straight wings (cv+). Both traits are encoded by autosomal genes that are linked. A cockroach has genotype bu+ bu cv+ cv, and the genes are in repulsion. Which of the following sets of genes will be found in the most-common gametes produced by this cockroach?a. bu+ cv+b. bu cvc. bu+ bud. cv+ cve. bu cv+

Answer 1

e. bu cv+

Step-by-step explanation:

The genes bu+/bu and cv+/cv are autosomal and linked --> each homologous chromosome has an allele of both bu+/bu and cv+/cv genes.

The cockroach is heterozygous for both genes, and they are in repulsion.

That means that on one of the homologous chromosomes one of the genes has a dominant allele and the other gene has the recessive allele, and on the other homologous chromosome the alleles are arranged in the opposite way.

In this case, the genotype of the cockroach would be best written as:

`(bu+\ \ \ cv)/(bu\ \ \ cv+)`

The most common gametes will be the parentals, i.e. gametes in which crossing-over between homologous chromosomes did not happen and therefore have the same distribution of alleles as the parental individual.

For those reasons, the most common gametes will be:

• bu+ cv
• bu cv+