1 Martle plants have either round or oval shaped fruit When

1) Martle plants have either round or oval shaped fruit. When a true-breeding oval shaped martle plant was crossed with a true-breeding round shaped martle plant, all the martles produced were round. What genotypes, phenotypes and ratios would you expect to see if you back-crossed these martle plants (the F₁ offspring) with the oval shaped martle parent plant? (Explain / Show Work)

2) Mauble cats have long whiskers resulting from the Wh allele which is dominant to the normal whisker allele wh. In these cats, gray fur color (G) is dominant to black fur color (g). A gray cat with normal whiskers mates with a black cat with long whiskers. (Explain / Show Work)

a) List the genotype(s) and phenotype(s) of the F₁ offspring.

b) List the genotype(s) and phenotype(s) of the F₂ offspring along with the expected ratios for each type.

c) If one of the F₁ cats mated with a black cat with normal whiskers, what genotypes, phenotypes and ratios would you expect to see in the offspring?

Solution

1).

Assume that the gene coding for round martles is R and the gene coding for oval martles is r. The genotype of true breeding round martles is RR and the genotype of true breeding oval martles is rr.

Parental -à RR* rr -à Rr (100% round)

Back cross Rr -à Rr* Rr --à R_ (75%, round), rr (25%, oval)