Ared flowered plant was crosssed with a white flower variation of the plant. all of the flowers on the next generation of plants were red. decide which flower color is recessive for this plant and which is dominate.

this is called a test cross. since all the next generation flowers were red we can safely say that the color red is dominant this is because the parent red flower can either have a genotype of homozygous dominant RR or heterzygous Rr. while the white flower has to be homozygous reccessive rr. since all the offspring was red the genotype of the parent red flower is RR and red is dominant over white.
  hope this helps