Question

Imagine you are breeding plants. Your goal is to breed a pure blue flower. You have a field of flowers growing now. But alas, you did two years ago as well! When these flowers reproduced, you ended up with a field that was three-fourths blue and one-fourth pink. What can you do to be sure that the flowers you are breeding will breed true blue? Outline the procedures and the rational for choosing them.

Answer 1

well, that would mean that blue is dominant, and pink is recessive, you would have to get both homozygous blue, otherwise the will not be true blue.

Answer 2

The correct answer would be a test cross.

A test cross is a cross which helps in determining the genotype of an individual who has a dominant trait.

The individual with a dominant trait is crossed with the individual with homozygous recessive genotype.

If all the offspring produced show dominant phenotype then, the individual was homozygous dominant and if the offsprings show both phenotypes then the individual was heterozygous dominant.

For example, the pink color is a recessive trait as it is present only in one-fourth of organisms.

So, the genotype of the blue flower can be determined by crossing it with the pink flower plant.

If all the offsprings show blue color flowers then the parent was homozygous dominant, that is, true breed.

If offspring have both blue and pink flowers, then the parent plant was heterozygous dominant.