Question

In Japanese four o'clock plants red (R) color is incompletely dominant over white (R') flowers, and the heterozygous condition (RR') results in plants with pink flowers. For each of the following construct a Punnett square and give phenotypic and genotype ratios of the offspring.
a. a red plant and a white plant
RR R'

R R R'

Genotypic ratios:

Phenotypic ratios:

Answer 1

Answer:

Phenotypic ratio: 0 Red : 4 Pink : 0 White

Genotypic ratio: 0RR : 4RR' : 0R'R'

Explanation:

This question involves a single gene coding for flower colour in Japanese four o'clock plants. The allele for red color (R) exhibits incomplete dominance over the allele for white color (R'), hence, they form a hybrid (RR') that is blending of both phenotypes (Pink).

In a cross between a red plant (RR) and white plant (R'R'), red and white four o'clock plant will produce gametes R and R' respectively. Using these gametes in a punnet square (see attached image), four possible offsprings that all have a genotype: RR' will be produced. This means that all offsprings of this cross are pink colored.

Therefore,

Genotypic ratio= 0RR : 4RR' : 0R'R'

Phenotypic ratio= 0Red : 4Pink : 0White