Question

In carnations, the alleles for flower color exhibit incomplete dominance. Red

flowers have the RR genotype. Pink flowers have the RW genotype. White
flowers have the WW genotype.

If a red flower and a pink flower are crossed, what is the expected genotypic
ratio of their offspring?

A. 2 RR:2 RW:0 WW
B. 1 RR: 3 RW:0 WW
C. O RR:2 RW: 2 WW
D. 1 RR:2 RW: 1 WW

Answer 1

The genotypic ratio of offspring from a cross between a red (RR) and a pink (RW) carnation is 2 RR:2 RW:0 WW, which shows incomplete dominance in flower color. So the correct option is A.

Step-by-step explanation:

In carnations, flower color is governed by incomplete dominance. The genotypic ratio for the offspring of a red flower (RR) crossed with a pink flower (RW) can be determined using a Punnett square. The possible genotypes for the offspring are RR (red), RW (pink), and WW (white).

Setting up the Punnett square:

• Place the alleles from one parent across the top (R and R for the red flower).
• Place the alleles from the other parent along the side (R and W for the pink flower).

Fill in the squares:

• Top-left square: RR (red)
• Top-right square: RR (red)
• Bottom-left square: RW (pink)
• Bottom-right square: RW (pink)

The genotypic ratio for the offspring from this cross is:

1. 2 RR (red)
2. 2 RW (pink)
3. 0 WW (white)

Hence, the correct ratio is 2 RR:2 RW:0 WW, which aligns with answer choice A.

Answer 2

In the case of incomplete dominance in carnations, the genotypic ratio of the offspring resulting from a cross between a red flower (RR genotype) and a pink flower (RW genotype) would be:

D. 1 RR:2 RW: 1 WW

This means that for every offspring, there would be one with the RR genotype (red flower), two with the RW genotype (pink flower), and one with the WW genotype (white flower).