Suppose a man is heterozygous for heterochromia, an autosomal dominant disorder which causes two different-colored eyes in an individual, produced 25 offspring with his normal-eyed wife. of their children, 14 were heterochromatic and 11 were normal. calculate the chi-square value for this observation.

If we assume Aa is husband which is hetero-zygote and aa is wife which is normal then their cross will be Aa X aa and first generation will be Aa aa aa Aa.

Further explanation

Cross between Aa (heterozygote male) and aa (normal female)

Here is cross between a normal wife (aa) and a heterozygote husband (Aa)

Aa X aa

First generation

Aa Aa aa aa

Result

It is clearly seen that ration is 1:1 which mean half are heterozygote and half are normal offspring. As they already told about number of offspring which is 25, So according to 1:1 12.5 are normal and 12.5 are heterozygote.

Chi-square Test

It is test used to evaluate the observed the expected values.  

Chi-square formula

χ2=∑(o-e)2/e

Here o= observed and e= expected

Calculation through chi-square value

It is given below

For heterozigous (14-12.5)2/12.5=0.18

For normal (11-12.5)2/12.5=0.18

By putting values of both heterozygous and recessive in chi-square formula

χ2=0.18+0.18=0.36

Answer details

Subject: Biology

Level: High school

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