Biology / Unit 5 Bio 1035 short lesson, about 20 seconds
The Punnett Square
Captions available
The idea
A Punnett square is a grid crossing one parent's possible gametes against the other's, showing every offspring genotype and its expected frequency.
In practice
A 2-by-2 Punnett square for a Yy-by-Yy cross shows one YY, two Yy, and one yy square, a 1:2:1 genotype ratio.
Where people slip
A Punnett square shows the population-level expected ratio — it does not predict any one individual offspring's actual genotype.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
Something wrong in this lesson? Flag it · Sources for Biology