In the laboratory, a genetics student crossed flies with normal, long wings to flies with mutant, dumpy wings, which she believed was a recessive trait. In the F1, all flies had long wings. In the F2, the following results were obtained: 672 long-winged flies 218 dumpy-winged flies The student tested the hypothesis that the dumpy wing is inherited as a recessive trait by performing chi-square analysis of the F2 data. Determine:
a. Chi-Square Value.
b. Degrees of freedom.
c. Reject or fail to reject the hypothesis.

a. Chi-Square Value = 0.12

b. Degrees of freedom = 1

c. Reject or fail to reject the hypothesis = fail to reject the hypothesis

Explanation:

Available data:

Let us name the allele for Long L and the allele for dumpy l

The number of observed individuals:

In the F2 generation, if l was a recessive allele and L a dominant allele, exhibiting complete dominance, we would expect a 3:1 phenotypic ratio.

Cross:          Ll   x   Ll

Gametes)   L   l    L  l

Punnett square)   L     l

                     L    LL    Ll

                      l     lL     ll

F2) 3/4 LL + Ll long-winged individuals

      1/4 ll dump-winged individuals

From this ratio and the total number of individuals in the F2 generation, we can get the expected number of individuals:

4 possible genotypes 890 individuals

3 LL + Ll genotype X = 667.5 long-winged individuals

1 ll genotype X = 222.5 dump-winged individuals

Chi square = ∑ (O-E)²/E

LL + Ll = (O-E)² /E

LL+ Ll = (672 - 667.5) ² / 667.5

LL + Ll = 0.03

ll= (O-E)²/E        

ll= (218 - 222.5)² / 222.5

ll= 0.09  

0.12 < 3.84 meaning that there is enough evidence to reject the null hypothesis.

Fail to reject the hypothesis.  The genotypes in the population might be in equilibrium H-W. L is the dominant allele, and l is the recessive allele. The dumpy wing is inherited as a recessive trait.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides