In the fruit fly Drosophila melanogaster, two genes control eye color and wing shape:

For eye color, the allele for red eyes ( $E$ ) is dominant to the allele for sepia eyes ( $e$ ).
For wing shape, the allele for normal wings ( $V$ ) is dominant to the allele for vestigial wings ( $v$ ).

A geneticist crossed two Drosophila flies that were heterozygous for both genes ( $E e V v$ ). The expected phenotypic ratio of their offspring under the hypothesis of independent assortment is $9 : 3 : 3 : 1$ .

The geneticist obtained a total of $320$ offspring from this cross. The observed numbers for each phenotype were:

Red eyes, normal wings: $171$
Sepia eyes, normal wings: $69$
Red eyes, vestigial wings: $54$
Sepia eyes, vestigial wings: $26$

Use the chi-squared formula

\chi^2 = \sum \frac{(O - E)^2}{E}

to calculate the $χ2\chi^2$ value for these data.

State the number of degrees of freedom for this test.

Using the critical values table below (for $p = 0.05$ ), determine whether the null hypothesis (that there is no significant difference between the observed and expected results) should be accepted or rejected, and explain your answer.

Degrees of freedom	Critical value ( $p = 0.05$ )
1	3.84
2	5.99
3	7.82
4	9.49

In the fruit fly Drosophila melanogaster, two genes control eye color and wing shape:

For eye color, the allele for red eyes ( $E$ ) is dominant to the allele for sepia eyes ( $e$ ).
For wing shape, the allele for normal wings ( $V$ ) is dominant to the allele for vestigial wings ( $v$ ).

The geneticist obtained a total of $320$ offspring from this cross. The observed numbers for each phenotype were:

Red eyes, normal wings: $171$
Sepia eyes, normal wings: $69$
Red eyes, vestigial wings: $54$
Sepia eyes, vestigial wings: $26$

Use the chi-squared formula

\chi^2 = \sum \frac{(O - E)^2}{E}

to calculate the $χ2\chi^2$ value for these data.

State the number of degrees of freedom for this test.

Degrees of freedom	Critical value ( $p = 0.05$ )
1	3.84
2	5.99
3	7.82
4	9.49

Analysis

Question 33

Markscheme

Analysis

Question 33

Markscheme

Analysis

Question 33

Analysis Questions

Analysis

Question 33

Analysis Questions