4. In tomatoes, red fruit color is dominant to yellow Suppose a tomato plant hom

Question

4. In tomatoes, red fruit color is dominant to yellow Suppose a tomato plant homozygous for red is crossed with one homozygous for yellow Determine the phenotype and genotype of a) the F1 offspring b) the offspring of a cross of the F1 back to the red parent c) the offspring of the F1 back to the yellow parent 5. In the fruit fly, Drosophila melanogaster, the allele for dumpy wings (d) is recessive to the normal long-wing allele, (D) and the allele (W). In a cross of DDWW with Ddww, allele for white eye (w) is recessive to the normal red-eye what proportion of the offspring are expected to be "normal (long wings and red eyes)? What proportion are expected to have dumpy wings and white eyes?

Explanation / Answer

Red (R) is dominant to yellow (r).

RR X rr

All progeny will be Red phenotypically and a heterozygous genotypically.

Offspring: RR. RR, Rr, Rr

50% of the progeny will be Red homozygous and 50% heterozygous genotypically

While phenotypically 100%progeny will be Red.

Offsprings: Rr, Rr, rr, rr

Phenotypically 50% progeny will be red and 50% will be yellow.

While genotypically 50 % will be heterozygous red and 50% yello.

5. Dumpy wing (d) is recessive, normal wing dominant (D)

White eye recessive (w) to the red eye (W).

DDWW X DdWw

DW

Dw

dW

dw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

Proportion for long wing red eyes

All of the 16 progeny will be long winged and red eye (Atleast one dominant allele of D and W)

And none of them will be dumpy wings and white eye (No homozygous w or D)

DW

Dw

dW

dw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

DW

DDWW

DDWw

DdWW

DdWw

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