Question

. In a fruit fly experiment, two gray-bodied fruit flies produce mostly gray-bodied offspring, but some of the offspring have black bodies. If there are 280 offspring, how many will you predict will have grey bodies and how many will have black bodies? How many of the 280 offspring do you predict will be heterozygous

Answer 1

25% will have black bodies. 50% will be heterozygous. Basically the only way you could have black is if it was recessive and both of the parents were heterozygous, Gg. Grey is dominant, with GG and Gg both producing grey. Black is recessive and will ony occurs with the genotype gg. 25% of 280 is 70, so 70 will be gg, homozygous black. 50% will be Gg, heterozygous grey, which would be 140. The last 70 will be the last 25%, and they will be GG, homozygous grey. So overall 70 will be black and 210 will be grey :)

Answer 2

Assuming a single diallelic gene that expresses complete dominance, the number of black individuals is 70. The number of grey individuals is 210. The number of heter0zyg0us grey individuals is 140.

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Available data:

• Two gray-bodied fruit flies are crossed
• F1) Most of the progeny is gray-bodied and a few have black bodies
• N = 280

We will assume that body color is coded by a single diallelic gene, that expresses complete dominance.

We know that both phenotypes show up among the progeny, being the grey color the most frequent phenotype.

According to this information, we can assume a cross between two heter0zyg0us individuals, and a phenotypic ratio 3:1 of the progeny.

Let us say that

• G allele is dominant and expresses grey color.
• g allele is recessive and expresses black color

Cross:

Parentals) Gg   x   Gg

Gametes) G   g    G    g

F1) Genotype

• 1/4 = 25% GG
• 2/4 = 1/2 = 50% Gg
• 1/4 = 25% gg

Genotypic ratio 1:2:1

     Phenotype

• 3/4 Grey color, G-
• 1/4 Black color, gg.

Phenotypic ratio 3:1

Now, we know that the total number of individual in the F1 = 280

So we need to calculate the expected number of black and grey individuals, and among the grey ones, how many of them are heter0zyg0us.

100% of the progeny ---------------------------- 280 individuals

75% grey individuals -----------------------------X = 210 grey flies

25% black individuals ---------------------------X = 70 black flies.

75% grey individuals -----------------------------210 grey flies

50% heter0zyg0us ------------------------------ X = 140 heter0zyg0us grey flies

25% h0m0zyg0us -------------------------------- X = 70 h0m0zyg0us grey flies.

Grey individuals ⇒ 210 ⇒ 140 heter0zyg0us + 70 h0m0zyg0us dominant

Black individuals ⇒ 70 h0m0zyg0us recessive.

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Related link:  brainly.com/question/24675464?referrer=searchResults