Punnett follows on from SimpleGene. Here the student works out genetic ratios for 2 loci. There are two methods for doing this, the Punnett square method and the probability method, and the program covers both.

We start out with a template for all genes and phenotypes.

The animal in question is the 'cowdog', with two variable characters:

After a certain amount of work on the student's part, the following screen is built up:

The program now concentrates on the two individual characters:

It shows that the ratio is the same for the spot character regardless of the animal's colour:

This is translated into a calculation on proportions and then on frequencies:

Finally the student gets to try out a few examples such as the following:


Download the software now to your computer to view the program the way your students will view it.

 Windows version  Macintosh version


Last updated on 19 April 2001 -->