This is an example of a back-cross to determine the genotype of a plant that shows the dominant phenotype. It was revealed to be heterozygous at one locus (R/r) and homozygous at the other (Y/y).


In sweet peas purple flower color and long pollen grains are dominant over red flower color and round pollen grains but the genes for both characters are on the same chromosome. Homozygous (purple and long with red and round) parents are crossed and then the F(1) plants are selfed. If cross-overs sometimes occur between these loci during meiosis, how many phenotypes should be represented in the F(2) generation: