Question

Three gene pairs located on separate autosomes determine flower color and shape as well as plant height. The first pair exhibits incomplete dominance, where color can be red, pink (the heterozygote), or white. The second pair leads to the dominant personate or recessive peloric flower shape, while the third gene pair produces either the dominant tall trait or the recessive dwarf trait. Homozygous plants that are red, personate, and tall are crossed with those that are white, peloric, and dwarf. Determine the \(F_{1}\) genotype(s) and phenotype(s). If the \(F_{1}\) plants are inter. bred, what proportion of the offspring will exhibit the same phenotype as the \(\mathrm{P}_{1}\) plants?

Short answer

Answer: When the F1 plants are interbred, the proportion of offspring exhibiting the same phenotype as the P1 plants is 3/64.

Step-by-step solution

Determine the genotypes of the P1 plants

We have the following information about the P1 plants: 1. Homozygous red (incomplete dominance) 2. Dominant personate flower shape (dominant-recessive) 3. Dominant tall plant height (dominant-recessive) Based on this information, we can determine the genotypes of the P1 plants: - For flower color: Homozygous red, so RR - For flower shape: Dominant personate, so PP - For plant height: Dominant tall, so TT The P1 genotype is therefore RR PP TT. The cross is between plants that are red, personate, and tall (RR PP TT) and plants that are white, peloric, and dwarf. Based on the given information: - For flower color: white (incomplete dominance), so rr - For flower shape: recessive peloric, so pp - For plant height: recessive dwarf, so tt The other P1 genotype is thus rr pp tt.

Determine the potential genotype combinations of the F1 generation

To find the genotypes and phenotypes of the F1 generation, we will set up three separate Punnett squares, one for each gene pair. Flower color (RR x rr): R|r R|r -+-+-- R|r R|r Flower shape (PP x pp): P|p P|p -+-+-- P|p P|p Plant height (TT x tt): T|t T|t -+-+-- T|t T|t

Determine the F1 genotype(s) and phenotype(s)

From the step 2, we can see that the F1 genotypes are: - For flower color: All offspring will be Rr (pink). - For flower shape: All offspring will be Pp (personate). - For plant height: All offspring will be Tt (tall). So, the F1 genotype(s) are Rr Pp Tt, with the phenotype being pink, personate, and tall.

Find the proportion of offspring with the P1 phenotype when F1 plants are interbred

Now, let's assume the F1 plants are interbred. We need to determine the proportion of offspring that will exhibit the same phenotype as the P1 plants (red, personate, tall for one P1 plant and white, peloric, dwarf for the other P1 plant). First, we'll create Punnett squares for the F1 generation for each gene pair. Flower color (Rr x Rr): R | R| r| r --+--+--+ r | Rr|Rr|rr --+--+--+-- r | Rr|Rr|rr Flower shape (Pp x Pp): P | P| p --+--+-- p | Pp|pp Plant height (Tt x Tt): T | T| t --+--+-- t | Tt|tt Now, let's find the proportions for each phenotype. 1. For red, personate, and tall (RR PP TT): Flower color: 1/4 (RR) Flower shape: 1/2 (PP) Plant height: 1/4 (TT) The probability of the red, personate, and tall phenotype will be: \(\frac{1}{4}\times\frac{1}{2}\times\frac{1}{4}=\frac{1}{32}\) 2. For white, peloric, and dwarf (rr pp tt): Flower color: 1/4 (rr) Flower shape: 1/4 (pp) Plant height: 1/4 (tt) The probability of the white, peloric, and dwarf phenotype will be: \(\frac{1}{4}\times\frac{1}{4}\times\frac{1}{4}=\frac{1}{64}\) When the F1 plants are interbred, the proportion of offspring exhibiting the same phenotype as the P1 plants will be \(\frac{1}{32}+\frac{1}{64}=\frac{3}{64}\).