Question

You are studying wing colour in butterflies. You cross pure-breeding male butterflies that have blue wings with yellow eyespots, with pure-breeding female butterflies with orange wings and black eyespots.

The F1 males all have orange wings and black eyespots, while the females have blue wings and yellow eye spots. You cross the F1 males and females and obtain the following F2 (the male and female F2 give the same ratios):

90 with orange wings and black eyespots

90 with blue wings and yellow eyespots

10 with orange wings and yellow eyespots

10 with blue wings and black eyespots.

Fully interpret the results, explaining the original parental genotypes, the genotypes of the F1 and how the F2 are generated.

Answer 1

answered this

b) In a pure breeding oraganism, the parents always passed down a trait or phenotype to the offspring. The parents and offsprings in trub breeding will always share the same genotype.

c) in cross A, solid orange wings represent dominant character and black and orange wings means they are recessive. Let assume A= dominant, solid orange and a= recessive, black, orange. As they are purebreed, the cross was betwen dominant and recessive homozygous. The offspring will have heterozyguos phenotype and the F1 offspring will have heterozygous genotype which will show dominant phenotype.

d) If the trait is sex linke, then the male will have the genotype Z^aZ^a and the female will have the genotype Z^AW. The offspring thus will have the genotype Z^A Z^a ( male) and Z^aW ( females).

e) If the wing colour trait is autosomal then the offspring will have Aa genotype and they will show orange and black wing colour.

f) The possible genotypes of the offspring will be Z^A/Z^a, Z^A/W, Z^a/Z^a, Z^a/W and the ratio will be 1:1:1:1.

	ZA	Za
Za	ZA Za	Za Za
W	ZA W	Za W

Half of the offspring will be male and half of the offspring will be female. Half of them will have solid orange and half will have black and orange.