Dominance — Science definition
The stated rule relating genotype to appearance; under complete dominance one copy of the dominant allele is enough to produce its effect.
Where it is taught
- Inheritance, Probability & Punnett Squares — Genes, Cell Division & Heredity, Life Science & Scientific Inquiry, Grade 7
In use
Turning genotypes into appearances needs a stated rule, and the usual one is complete dominance: an allele is dominant if one copy is enough to produce its effect, and recessive if its effect appears only when no dominant allele is present.
Inheritance, Probability & Punnett Squares
Questions using dominance
Problem 1
Does dominance make an Aa parent transmit A more than half the time in this model?
Answer and explanation
No. Dominance concerns phenotype expression, while the supplied gamete probabilities remain one half A and one half a.
Problem 2
In the stipulated Aa×Aa complete-dominance model, what percent of offspring events are expected to be aa?
Answer and explanation
25 %
One of four equally probable combinations is aa: 1/4×100=25%.