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traits less likely to be chosen (like the tT/Tt generation was crossed,

the short trait) recessive. the plants could have all four
combinations. Three out of the four
His experiments showed that if a
combinations (TT, tT, and Tt) yield
plant with a dominant trait and a
dominant traits, while the fourth
plant with a recessive trait
combination (tt) yields short
reproduced the F1 generation
plants. Thus ¾ = 75%, and ¼ =
would be 100% dominant trait. For
25%.
example, all of the offspring of the
tall and short plant were tall. But, A good way of visualizing these
the F2 would always be 75% results is with Punnett Squares.
dominant and 25% recessive—and Punnett squares are simply tables
F2 generation that was 75% tall we can use to show the possible
and 25% short, in our example. combinations of traits. In our
Tall/short example we can draw
The dominant traits are designated
this Punnett Square:
by a capital letter, and the
recessive traits are designated by a Parental (P) Generation: TT
lowercase letter. For example, the crossed with tt
dominant trait “tall” is designated

the letter T, while short is given The Recessive Plant
the lowercase letter t. Since the
The t T
plants have two copies of each trait
Dominant
the combinations can be either TT, T Tt Tt
Plant
Tt, tT, or tt.
T Tt Tt
If both copies are dominant, than
the dominant trait is seen (TT= tall

plant). If there’s a mix, than the
dominant trait is seen (Tt/tT = tall Result: 100% Tt. 100% tall.
plant). If both traits are recessive, F1 Generation: Tt crossed with
than the recessive trait is seen (tt Tt
= short plant). Since three of the
four options result in tall plants, T T

and one of the four results in short
T TT Tt
plants, it makes sense that Mendel
observed the results he did.
t tT Tt
That’s because after the first

generation of TT X tt all of the
plants were Tt and tT. But, when

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