A gardener is growing plants in his backyard and decides to mate a Tall, White flowering plant (DDww) with a Dwarf, Purple (ddWW) flowering plant of the same species. When the plants start to bloom he is surprised that the pair has only produced Tall, Purple offspring. In your own words, explain how this is possible.

Tallness allele is dominant over dwarfness allele and purple allele is dominant over white allele.

Explanation:

Tall, white flowering plant DDww was mated with dwarf, purple flowering plant (ddWW).

DDww x ddWW

Offspring: all DdWw (tall and purple)

Since all the offspring appeared tall and purple, it means that the tallness allele (D) is dominant over the dwarfness allele (d) while the purpleness allele (W) is dominant over the whiteness allele (w). Both d and w are said to be recessive.

In a trait that is defined by dominant/recessive alleles, the dominant allele always masks the expression of the recessive allele.