Answer:
Due to presence of dominant and recessive trait
Explanation:
Mendel in his experiment found that when he crossed a true breeding pea plant (TT) with a true breeding short pea plant (tt), then all the first generation offspring were tall (Tt). However, in second generation, short pea plant reappeared.
Form this, he devised that allele for specific trait like tallness “T” is dominant over recessive trait i.e “t” as when these two allele occur together the characteristic of “t” are not expressed. In fact, a recessive allele like “t” will occur only when they are in pair i.e tt
