AP Biology· difficulty 3/5
A test cross of an unknown (showing dominant phenotype) × aa yields all dominant offspring. The unknown parent is most likely
Cannot tell
Heterozygous (Aa)
Homozygous recessive (aa)
Homozygous dominant (AA)
Explanation
AA × aa → all Aa, all dominant. Aa × aa → half dominant, half recessive. All-dominant offspring strongly suggest AA.
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