1. Certain breeds of cattle exhibit scurs, which are small hornlike growths on t

Question

1. Certain breeds of cattle exhibit scurs, which are small hornlike growths on the frontal bone in the same location where horns in other breeds of cattle would grow. This trait (controlled by a single gene that exists in Sc and sc alleles) is dominant in males and recessive in females. A male with the genotype Sc sc has _____, and a female with the genotype Sc sc has _____.

a. scurs; no scurs.

b. scurs; scurs.

c. no scurs; scurs.

d. no scurs; no scurs.

e. There is not enough information given to predict each sex’s phenotype.

2. Elongated (E) and Five (F) are linked genes in a housefly that are 24 cM apart. The E allele produces elongated wings, which is dominant to the e allele that produces small wings. The F allele produces five stripes on the back of the fly, which is dominant to the f allele that produces four stripes. In the cross EeFf x eeff, what proportion of the offspring should have elongated wings and five stripes?

Explanation / Answer

1.As the trait is dominant in male so the trait will be shown by the genotype Scsc and ScSc. The trait is recessive in emale so the trait will be shown only be the genotype scsc.

So the ans is a) The male with genotype Scsc has Scurs and a female with genotype Scsc has no scurs.

2. As E and F are linked genes so the gamates formed from EeFf gene will be EF and ef and from eeff the gamates will be ef and ef.

EeFf

Elongated wings &five stripes

EeFf

Elongated wings &five stripes

eeff

small wings and four stripes

eeff

small wings and four stripes.

So 50% of the population will have elongated wings and five stripes

EeFf

Elongated wings &five stripes

EeFf

Elongated wings &five stripes

eeff

small wings and four stripes

eeff

small wings and four stripes.

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