A cross is made between two true-breeding strains (P1generation) in Drosophila. The
following F2 data were obtained by intercrossing the F1 malesand females from this cross:
Phenotype # of flies
Claret eyes, wildtype bristles 255
Red eyes, frizzled bristles 248
Red eyes, wildtype bristles 497
Claret eyes, frizzled bristles 0
a) What were the phenotypes of the F1 males and F1 females thatwere crossed to produce the
F2 generation?
b) What were the genotypes of the F1 males and F1 females thatwere crossed to produce the F2
generation?
c) Explain whether a student can conclude that claret eyes aredetermined by a recessive allele of
an autosomal gene.
d) Can the student conclude that the 2 genes are syntenic (onthe same chromosome)? Explain.
e) Indicate the genotypes of the gametes that will be producedby the F1 males and females.
f) Illustrate, using appropriate symbols and convention, thegenotypes of the two true-breeding
parents of the F1 generation.
g) Predict the expected number of male and female flies in eachof the 4 phenotypes in a
population of 2000 flies, if the F1 male is crossed to a femalefrom a tester strain with claret
eyes and frizzled bristles.
A cross is made between two true-breeding strains (P1generation) in Drosophila. The
following F2 data were obtained by intercrossing the F1 malesand females from this cross:
Phenotype # of flies
Claret eyes, wildtype bristles 255
Red eyes, frizzled bristles 248
Red eyes, wildtype bristles 497
Claret eyes, frizzled bristles 0
a) What were the phenotypes of the F1 males and F1 females thatwere crossed to produce the
F2 generation?
b) What were the genotypes of the F1 males and F1 females thatwere crossed to produce the F2
generation?
c) Explain whether a student can conclude that claret eyes aredetermined by a recessive allele of
an autosomal gene.
d) Can the student conclude that the 2 genes are syntenic (onthe same chromosome)? Explain.
e) Indicate the genotypes of the gametes that will be producedby the F1 males and females.
f) Illustrate, using appropriate symbols and convention, thegenotypes of the two true-breeding
parents of the F1 generation.
g) Predict the expected number of male and female flies in eachof the 4 phenotypes in a
population of 2000 flies, if the F1 male is crossed to a femalefrom a tester strain with claret
eyes and frizzled bristles.
