LET’S TRY ONE
In an invented plant, A is dominant over a. Which allele pair is heterozygous, meaning two different versions?
Aa
Aa contains two different allele versions.
Learning steps & teaching tips
Use stated allele rules and equally likely model outcomes without generalizing a single-gene model to every trait.
- Read which allele versions each parent can contribute.
- Combine one contribution from each parent.
- Count model outcomes and distinguish probability from a guarantee for a small family.
Try it together
Use two coins labelled A/a to make a model cross. Record possible pairs, then explain why four real offspring need not match the model's proportions exactly.
List the possible allele pairs and use only the dominance rule given for this invented plant trait.