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BBiologyMathematicsS4 · S5 · S6Genetics
Genetics lab: maize cobs and the chi-squared test
Each kernel on a maize cob is a separate offspring. Count the kernels on cobs from different crosses and test whether the results fit Mendel’s ratios.
LevelS4, S5 and S6 (and A Level, IB)
TimeAbout 45 min
You useKernel counts, ratios, chi-squared
PriceFree: no account
🎯 Aim
To count the phenotypes of maize kernels from different crosses and use the chi-squared test to decide whether the results fit the expected Mendelian ratios.
You will learn to
- Predict ratios from monohybrid, test and dihybrid crosses.
- Count and record phenotypes accurately.
- Calculate expected numbers and chi-squared.
- Use degrees of freedom and a critical value to make a conclusion.
🧭 What to do
- Choose the F2 cross. Tap Count the kernels and read the numbers.
- Look at the chi-squared table: compare χ² with the critical value.
- Tap Next cob and Add to the class total several times: what happens to χ²?
- Try the Test cross and the Dihybrid F2 cross.
- Answer the questions with the class data (cobs 1–6).
- Write your conclusion and download your lab report.
📋 The data
Kernel counts from six simulated cobs (each kernel is one offspring).
🧠 Investigate: answer from the data
Type your answer and tap Check. Use 💡 Hint first; open the method only when you are stuck.
➕ Get more from this experiment
📝 Free
Print the worksheet (button above), download the data, and save your report. Teachers can project this page in class.
📦 Premium Lab Pack
1 000 RWF
- Worksheet: real maize cob counting with recording tables
- Chi-squared table and practice problems
- Teacher guide and answer key
- Exam-style genetics questions with marking scheme
👩🏫 For teachers
Use it as a practical when apparatus is missing, as homework, or as a project. Free lesson plans help you plan, teach and assess.
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