Incomplete Dominance—Predicting Flower Color in Snapdragons

Question

Snapdragons are popular garden plants that produce brightly colored flowers. When a plant that is homozygous for white flowers is crossed with a plant that is homozygous for red flowers, all offspring are pink. Snapdragons are an example of a plant that exhibits an inheritance pattern called incomplete dominance.

(Score for Question Click or tap here to enter text. 1: of 2 points)

Determine the genotype of each parent plant and write them below. Use W to indicate the allele for white flowers and w to indicate the allele for red flowers.

Genotype of homozygous parent plant with white flowers: WW

Genotype of homozygous parent plant with red flowers: ww

(Score for Question 2: Click or tap here to enter text. of 4 points)

Next, think about the gametes each parent plant will produce. List the allele in each gamete.

Parent plant with white flowers:

Gamete 1: WW

Gamete 2: Ww

Gamete 3: wW

Gamete 4: ww

Parent plant with red flowers:

Gamete 1: WW

Gamete 2: Ww

Gamete 3: wW

Gamete 4: ww

(Score for Question Click or tap here to enter text. 3: of 2 points)

The two parent plants are the P generation, or parent generation. Create a Punnett square to show their offspring, the F1 generation.

Part 1 Punnett Square

	P	p
P	PP	Pp
p	Pp	pp

Answer:

Type your answer here Click or tap here to enter text.

(Score for Question 4: Click or tap here to enter text. of 1 points)

What pattern do you notice in the genotypes of the F1 generation snapdragons?

This last question is all I need.

Answer 1

Each original parent was homozygous or pure for their particular allele (gene for a trait.)

The symbols RR and WW best represent the pure condition of each parent plant.

When these two parent plants are crossed the resulting offspring will all be RW

RR X WW

RW because one parent contributes a R (red) gene in their gametes and the other a W (white) gene

Since this is blended inheritance the resulting phenotyphic expression will all be pink, all F1 offspring will have the genes RW.

However, when the F1 are crossed (RW x RW) this allows a return of the red, white phenotypes along with the combination of alleles giving the phenotype Pink......

Answer 2

Incomplete dominance is a concept that arises when the phenotype of what would carry the dominant alleles as heterozygous do not completely show in phenotype as the dominant phenotype but instead display a phenotype that is somewhere in the middle of what the recessive phenotype would typically display and also what the dominant phenotype would display while carrying alleles for both, hence pink is displayed when one dominant allele, W for white and w for red result in a phenotype of pink.

If 2 homozygous cross:

WW white and ww red you would have:

W W.

w Ww Ww

w. Ww Ww.

The entire first generation of offspring from the parents of homozygous dominant WW and homozygous recessive would have a heterozygous genotype and display a pink color for 100% of offspring: Ww and pink in color.

Essentially the dominant and recessive phenotype or physical characteristics would be masked or go into hiding for that first F1 generation offspring with all the dragonflowers appearing pink.

When that second generation is emerged, or basically when F1 generation is crossed it will reveal. .

2 heterozygous Pink flowers with genotype:.

W w

W WW. Ww

w. Ww. ww.

So the F2 generation will have 1/4 or 25% of the flowers with the dominant white appearance and genotype alleles WW,. 2/4 or 50% of the flowers with the pink characteristics pink phenotype at Ww, and then 1/4 or 25% of the flowers with a phenotype of red recessive with alleles ww. The dominant and recessive phenotypes resurface in the F2 generation, white and red.