19 May, 14:26

# In Drosophila melanogaster, ebony body color is determined by the e allele. The e' allele produces the wild type honey-colored body. In heterozygotes for the two alleles, a dark marking called the trident can be seen on the thorax, but otherwise, the body is honey-colored. The e' allele is thus considered to be incompletely dominant to the eallele. When female e' e' flies are crossed to male e' eflies, what is the probability that progeny will have the trident marking? Animals with the marking mate among themselves. Of 300 progeny, how many would be expected to have a trident, how many would have ebony bodies, and how many would have honey-colored bodies?

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1. 19 May, 18:04
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a) 50% or 0.5

b) trident marking = 150

honey colour = 75

ebony colour = 75

Explanation:

Given,

e'e' = wild type honey colour

e'e = honey colour with trident

ee = ebony colour

a) e'e' X e'e:

e' e'

e' e'e' e'e'

e e'e e'e

50 % of the progeny has e'e genotype so 50% of the progeny will have trident marking.

b) e'e X e'e:

e' e

e' e'e' e'e

e e'e ee

50 % of the progeny has e'e genotype so 50% of the progeny will have trident marking = 300 * 0.5 = 150

25% of the progeny has e'e' genotype so 25% of the progeny will have honey colour = 300*0.25 = 75

25% of the progeny has ee genotype so 25% of the progeny will have ebony colour = 300*0.25 = 75