Use a Punnett's squares to show a monohybrid cross between pure breeding parents of tall (T) and dwarf (t) pea plants. The tall trait is dominant and thus is represented by the uppercase letter "T". The dwarf trait is recessive and is represented by
to lowercase letter "t".

Answer/Explanation:

True breeding means the parents have two copies of the same allele (two of the same letter)

That means the monohybrid cross is TT x tt

      T            T

t      Tt          Tt

t      Tt          Tt

All the offspring have one copy of each and are Tt. Tall is dominant to dwa rf. So all the offspring will be tall.

that is wrong, its not thymus.