L4 - Punnett Squares

• A punnett square is used to show the possible genotype and phenotype outcomes of two organisms reproducing.
• Pea plants can be tall or short. Being tall is dominant (T) and being short is recessive (t). If a tall pea plant which is homozygous dominant (TT) reproduced with a short pea plant which is homozygous recessive (tt), we could use a punnett square to show the outcomes.
• Cross two F1 offspring

  The offspring are all the same and so you can choose any two. This is called selfing.
• If we know the homozygous recessive phenotype then we know that organisms genotype.