In Drosophila black body (B) is dominant to gray (b) and long wings (L) is domin
ID: 3165670 • Letter: I
Question
In Drosophila black body (B) is dominant to gray (b) and long wings (L) is dominant to short wings (l). The F1 flies were produced by crossing a homozygous black, homozygous long winged fly with a gray short winged fly. (4)
a) Give the genotypes of the Parents and the F1.
b) If an F1 is testcrossed, what is the expected phenotypic ratio?
c) If the F1 are allowed to interbreed what are the expected phenotypes and probably proportions in the F2 generation?
d) If the F1 is mated with a true breeding black and long winged fly, what would be the expected phenotype(s) and the probably proportions of the F2 generation
Explanation / Answer
a) Give the genotypes of the Parents and the F1.
Parents genotype:
homozygous black, homozygous long winged fly =BBLL
gray short winged fly=bbll
All the F1 flies will be BbLl
Phenotype=heterozygous with black body and long wing
b) If an F1 is testcrossed, what is the expected phenotypic ratio?
BbLl x bbll
BL
Bl
bL
bl
bl
BbLl
Bbll
bbLl
bbll
1:1:1:1
1 black body and long wing
1 black body and short wing
1 Grey body and long wing
1 Grey body and short wing
c) If the F1 are allowed to interbreed what are the expected phenotypes and probably proportions in the F2 generation?
BbLl x BbLl
9 black body and long wing
3 black body and short wing
3 Grey body and long wing
1 Grey body and short wing
d) If the F1 is mated with a true breeding black and long winged fly, what would be the expected phenotype(s) and the probably proportions of the F2 generation
BbLl x BBLL
BL
Bl
bL
bl
BL
BBLL
BBLl
BbLL
BbLl
All the F2 flies will be of black body and long wings
BL
Bl
bL
bl
bl
BbLl
Bbll
bbLl
bbll