I think that the yellow body trait on a fruit fly is an X-linked recessive trait.  

We were given tables to analyze. Table 4.1 has an affected female an unaffected male. They had two types of kids, 64 affected males and 44 unaffected females.  One affected male and one unaffected female were bred together and they had four types of kids. 68 wild males and 63 yellow males, 57 wild females and 62 yellow females. Table 4.2 had an affected male and a wild female. They had 52 wild males and 57 wild females. When a wild male and a wild female were bred together they produced 88 wild males 42 affected males and 144 wild females. Table 4.3 has an affected male and an affected female. When they were bred together they had 84 affected males and 91 affected females. When one affected male and one affected female were bred together they had 80 affected males and 75 affected females. After analyzing the tables I made a pedigree for each table.

Pedigree 4.1 showed that there was an equal chance of males and females getting the trait. It also showed that the trait didn’t skip generations. The packet told us that the parents have to be homozygous. This means that the alleles have to be the same. Because of this, I thought that the trait was autosomal dominant, but after drawing Punnett squares my hypothesis was proven wrong. The Punnett squares showed that the offspring wouldn’t have the trait because the dominant trait always has to show.  I then realized that this trait could have been an X-linked recessive trait. I then made a Punnett square to see if my thought was right. The Punnett square proved me right because the Punnett square had both parents being homozygous there was a chance that the trait would show in the kids.

Pedigree 4.2 showed that there was not an equal chance of males and females getting the trait which automatically eliminated the chance of it being an autosomal trait. The pedigree also showed that the trait skipped a generation.  Because the first pedigree showed that the trait was X-linked recessive I thought that this pedigree would show the same thing. After making Punnett squares it also was proven that this was an X-linked recessive trait. The Punnett square showed that there was a chance of the trait skipping a generation. I then made a Punnett square that would show the chances of the F2 generation getting the trait. The Punnett square showed that the offspring could get the trait. It also showed that there was a chance that only 50% of the males could get the trait.

Pedigree 4.3 Showed that there was an equal chance that males and females could get the trait. The pedigree also showed that everyone in the family has the trait so there were no skipping generations. Because of the evidence presented on the pedigree, I thought that the trait would be Autosomal dominant, but that wouldn’t make sense because the other two pedigrees proved that it wouldn’t be. So, I made a Punnett square to see if I was right. Sure enough, it didn’t make sense. So I made a Punnett square that was X-linked recessive. This Punnett square once again proved that this trait is an X-linked recessive inheritance pattern. The Punnett square showed that 100% of the offspring would have the yellow body trait.

This evidence proves that the yellow body trait is an X-linked recessive trait. I made pedigrees and Punnett squares to further prove my evidence right.