Monohybrid inheritance and Chi squared

Pure breeding

Breeding of homozygous individuals that will alway result in a particular feature

When heterozygous individuals of the F1 generation are crossed, what’s the expected ratio?

3:1

Why do we not always see the 3:1 ratio?

• Random fertilisation

• Small sample size

What does Mendel’s law of segregation state?

In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of alleles can be present in a single gamete.

Draw a punnet square showing the crossing of 2 heterozygous individuals

What is Chi-square used to test for?

• If there’s any deviation between the observed frequency and the expected frequency

• Only be used on raw, categoric data

State the null hypothesis in Chi-squared

There’s no statistically significant difference between the observed and expected results

How do you calculate the Degrees of Freedom?

No. of categories - 1

x² > Critical value

• Reject null hypothesis

• There’s less than 5% probability results are due to chance

x² < Critical value

• Accept the null hypothesis

• There’s more than 5% probability results are due to chance