Biology / Unit 5 Bio 1061 short lesson, about 20 seconds
The 9:3:3:1 Ratio
Captions available
The idea
Self-crossing a dihybrid F1 heterozygote produces an F2 generation with four phenotype classes in a 9:3:3:1 ratio, when both traits assort independently.
In practice
A YyRr self-cross yields roughly nine yellow-round, three yellow-wrinkled, three green-round, and one green-wrinkled offspring per sixteen.
Where people slip
This exact ratio holds only under independent assortment — Bio 1067's linked loci produce a different, skewed proportion instead.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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