Question

In Mirabilis jalapa, the percentage of plants having pink and red flowers would be when the pink flower plant is test crossed.
A. 25% pink and 25% red
B. 50% pink and 50% red
C. 50% pink and 0%red
D. 0% pink and 0% red

Answer 1

Hint: Incomplete dominance is a type of inheritance and in it gives rise to offsprings with intermediates traits. In other words, in this type, one allele is not completely dominant over another and the offsprings inherit a mix of both dominant and recessive parental traits resulting in a new phenotype.

Complete answer: In incomplete dominance a single gene pair is involved and neither of them is dominant with respect to each other.
There is a deviation from the ratio obtained in the Mendelian monohybrid cross.
The $F_2$ generation gives rise to similar results both in terms of phenotypic ratio and genotypic ratio which is 1:2:1.
This can be seen in the plant snapdragon, where the cross between red and white flowered snapdragon plants results in an offspring having pink-colored flowers.
Now if the pink flower is crossed with a homozygous recessive white flower (test cross), then the results will be:

		Pink flower (Rr)
		R	r
White flower (rr)	r	Rr	rr
	r	Rr	rr

So, the right answer is option B. 50% pink and 50% red.

Note: The crosses are based on the laws of inheritance based upon the Mendelian laws. He included ratios and statistics in his studies to increase the credibility of all the data collected from his experiments.