Codominant Inheritance – Punnett Squares Worksheet (With Worked Example)

This student-friendly worksheet supports learners in understanding codominant inheritance through clear explanation, modelling, and structured practice with Punnett squares.

The resource begins with a fully worked example, guiding students step by step through the process of completing a Punnett square, calculating genotype percentages, and identifying phenotypes. Students then apply these skills across a series of carefully scaffolded questions, progressing towards more independent problem-solving.

A range of familiar biological contexts are used (including cattle coat colour, plants, chickens, fish, and horses) to help students recognise codominance as a consistent inheritance pattern rather than a one-off example.

Learning Objectives

Understand what codominant inheritance is

Complete Punnett squares for codominant traits

Identify genotype and phenotype ratios

Explain why codominant traits do not blend

Evaluate and correct common misconceptions

What’s Included

Clear explanation of codominance

Fully worked Punnett square example

10 structured practice questions

Gradual reduction of scaffolding

Short-answer and explanation questions

Challenge question to assess deeper understanding

Exit check for formative assessment

Complete answer key

Suitable For

KS3 / KS4 Biology

GCSE Science (Inheritance & Variation)

Secondary science revision or practice

Independent work, homework, or cover lessons

Format

Printable worksheet

Answer key included