Question

In a given hybridization between two flowers, red "R" is dominant, and white "r" is recessive. In a cross between two white-flowered plants, all of the offspring had white flowers. If a plant grower wanted to produce red flowers, what should s/he consider during breeding?
A) The breeder must introduce a plant that is homozygous dominant for white flowers.
B) The breeder must introduce at least one parent that is heterozygous for red flowers.
C) The breeder cannot manipulate the flower color. It would be best to begin with a different set of parent plants.
D) Flower color variation would depend on mutations in this case; there is no other way to change flower color of this population of plants.

Answer 1

The correct answer is B. The breeder must introduce at least one parent that is heterozygous for red flowers.

On crossing two white-flowered plants, all of the offspring with white flowers are produced in F1 generation. This indicates that both the parent are homozygous recessive (rr) for white colour. Then, to produce offspring with red flowers, the breeder should consider at least one heterozygous for red flowers (Rr) parent for breeding. Thus, on crossing one heterozygous red-flowered (Rr) with one white-flowered plant (rr), the red and white offspring will be produced in the ratio 1:1.

Answer 2

B is the answer that seems best.