Answer:
The pure tall plant has equal alleles (AA or aa) while the hybrid tall plant has one dominant and recessive allele (Aa).
Explanation:
When we say that an organism is pure, we mean that it is homozygous. In this case we are saying that, for a given trait, its alleles are equal. This means that the allele is occurring in double dose in that organism and, consequently, the gametes generated by it will be equal. A pure tall plant has alleles equal to "AA" or "aa".
When we refer to hybrid organisms, we are referring to heterozygous organisms. In this case we are saying that, for a certain characteristic, the alleles are different. For this reason, in gametogenesis, it is possible to observe the presence of two distinct gametes. A hybrid tall plant has different "Aa" alleles.