In a laboratory experiment of sexually-reproducing plants, a certain trait is determined by a single gene. The dominant allele has complete dominance over the recessive allele, resulting in two different phenotypes. Scientists created a new population of this plant by crossing 51 homozygous dominant individuals with 49 homozygous recessive individuals. The following results are from the first five generations of this population:

Generation Number of individuals with dominant trait Number of individuals with recessive trait Total number of individuals
1 51 49 100
2 285 0 285
3 270 90 360
4 315 105 420
5 375 125 500

Answer each part of this question completely in the space provided.
Based on the data, explain the phenotypic changes from generations 1 to 3.