PEAZIT Aha card
Go straight to resources ↓Inheritance: a table of chances, not a sibling schedule
In this model each parent has A and a and passes either with probability 1/2. Combinations are AA, Aa, aA and aa. With complete A dominance, the recessive trait appears only with aa.
| Observation | What it means |
|---|---|
| A from the second parent | AA or aA |
| a from the second parent | Aa or aa |
One worked example
- Aa × AaEach parent makes A or a gametes.
- AA, Aa, aA, aaFour equally likely combinations.
- aa: 1 out of 4The recessive genotype has probability 25%.
Watch out: This model concerns one gene with complete dominance and no other effects. It does not predict exact counts among four siblings.
Goal, prerequisites and card origin
What you will learn: Build a simple Aa × Aa cross.
What you need first: Probability and two alleles.
An original PEAZIT working card. Independent expert review and effectiveness testing have not yet taken place. · v1
Reference for the underlying principle ↗Show connections
In this model each parent has A and a and passes either with probability 1/2. Combinations are AA, Aa, aA and aa. With complete A dominance, the recessive trait appears only with aa.