Work out test cross ratio instantly with clear inputs, formula shown and shareable results.
Compares observed recessive offspring from a cross to a homozygous recessive tester with the expectation under each hypothesis for the unknown parent.
Test cross
Crossing with aa gives 50% recessive offspring if the unknown parent is Aa and none if it is AA
Ten offspring with no recessives gives about a 0.1% chance of missing a heterozygous parent, so around ten is usually enough.
Yes. A single recessive offspring proves the unknown parent carries the recessive allele.