ACT Preparation / Unit 22 ACT 2105 short lesson, about 20 seconds
Dominant and Recessive Alleles
Captions available
The idea
When an individual carries two different alleles, the dominant one is expressed and the recessive one stays hidden. A recessive trait shows only with two recessive alleles.
In practice
With black dominant over red, beetles with one or two black alleles are black; only two red alleles give red.
Where people slip
Two identical alleles make an individual homozygous; two different alleles, heterozygous.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Builds on
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