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IA Maize Genetics Experiment

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  • IA Maize Genetics Experiment

Experiments to calculate phenotype ratios.

In this lesson students are first introduced to a simple method of testing goodness of fit using a chi squared test. This is followed by a short experiment using maize cobs to predict and test genetic ratios. The third activity is slightly more complex online Drosophila breeding lab in which students design and test their own breeding experiments.

Lesson Description

Guiding questions

If here is a difference between a prediction and data from an experiment is the theory always wrong?

How can we tell if there is a significant difference between our theoretical value and experimental data?

Activity 1 - Testing a theoretical hypothesis using Chi Squared statistic

This worksheet Simple genetics using Chi2 to test a hypothesis explores a real case of genetics in a plant called the 'blue-eyed Mary. It is likely that the inheritance pattern is autosomal simple dominance. As these plants are not male or female separately then it is not possible to have sex linkage.

Complete the following worksheet to test the theory and to see how to use a chi-squared test in genetics.

Activity 2: Experiment to Calculate phenotype ratios in Maize cobs

Carry out the experiment on the worksheet Maize genetics lab worksheet.
Does the data you collect support the universality of DNA, at least in plant cells?

Activity 3 Online breeding experiments with Drosophila flies

This is a simple but effective online Drosophila breeding lab Great simple Drosophila breeding lab simulation

This ScienceCourseware Drosophila lab is a little more complex but very good too. It includes practice of Chi-squared tests.

https://www.sciencecourseware.org/vcise/drosophila/Drosophila.php?guestaccess=1
If you can't see the image blow, simply click on the direct link above to open this lab.

Teachers notes

The first activity is a simple illustration of the chi squared calculation to test goodness of fit. This really serves as an introduction for students to the chi squared calculation to test goodness of fit.

It is well worth explaining the way in which plants are "selfed" and how the plant does meiosis to make ovules and pollen, which become fused in fertilisation and make fruits full of seeds. The same is true of corn cobs which contain kernels that each represent an individual offspring. This makes if easy to sample many offspring from one single cob.

Simple Chi squared - Model Answers

 Model answers for the simple genetics sheet are available in the link and there is a Simple Chi squared - Model Answer here

Once students have done this quick calculation they will be able to analyse the maize cob experiment in activity two using the same method, and thus it could be used as an Internal assessment. However it is quite a simple method, and the data is rather simple for analysis. Better would be to design a similar experiment using one of the fly lab animations.

The third activity might make a good homework task or an introduction to a real lab using live Drosophila. There is plenty of scope for students to design their own crosses and the results can be analysed online using chi squared tests. Of course there is too much structured help in these simulations to use them for Internal Assessment without some careful thought and some restrictions for students. It is probably best to find some real Drosophila.