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 :)