As in Problem \(12,\) flower color may be red, white, or pink, and flower shape may be personate or peloric. For the following crosses, determine the \(P_{1}\) and \(F_{1}\) genotypes: (a) red, peloric \(\times\) white, personate 1 \(\mathrm{F}_{1}:\) all pink, personate (b) red, personate \(\times\) white, peloric 1 \(\mathrm{F}_{1}:\) all pink, personate (c) pink, personate \(\times\) red, peloric $\rightarrow \mathrm{F}_{1} \quad\left\\{\begin{array}{l}1 / 4 \mathrm{red}, \text { personate } \\ 1 / 4 \mathrm{red}, \text { peloric } \\ 1 / 4 \mathrm{pink}, \text { peloric } \\\ 1 / 4 \mathrm{pink}, \text { personate }\end{array}\right.$ (d) pink, personate \(\times\) white, peloric $\rightarrow \mathrm{F}_{1}\left\\{\begin{array}{l}1 / 4 \text { white, personate } \\ 1 / 4 \text { white, peloric } \\ 1 / 4 \text { pink, personate } \\ 1 / 4 \text { pink, peloric }\end{array}\right.$ (c) What phenotypic ratios would result from crossing the \(\mathrm{F}_{1}\) of (a) to the \(F_{1}\) of \((b) ?\)

Short Answer

Expert verified
In conclusion, by analyzing the given crosses using Mendelian principles and assuming dominant and recessive traits, we can determine the genotypes of the P1 and F1 generations. The phenotypic ratios for a cross between the F1 of (a) and F1 of (b) come out to be 1 red personate : 1 red peloric : 1 pink personate : 1 pink peloric : 1 white personate : 1 white peloric.

Step by step solution

01

Assuming dominant and recessive traits

Let's assume that red (R) and personate (P) are dominant traits, while white (r) and peloric (p) are recessive traits. So, the red peloric P1 genotype would be R_pp, and the white personate P1 genotype would be rrP_. F1 genotypes: --------------------------------------------------------------------------
02

Crossing the P1 genotypes

Crossing R_pp (red, peloric) and rrP_ (white, personate) results in F1 generation: Rp x rP = RrPp
03

Phenotype of F1 generation

So, the F1 genotype is RrPp, which results in pink (due to incomplete dominance) and personate phenotype. This matches with the given F1 phenotypes: all pink, personate. (b) red, personate × white, peloric P1 genotypes: --------------------------------------------------------------------------
04

Assuming dominant and recessive traits

Following the same assumptions as before, red personate P1 genotype would be R_PP, and white peloric P1 genotype would be rrpp. F1 genotypes: --------------------------------------------------------------------------
05

Crossing the P1 genotypes

Crossing R_PP (red, personate) and rrpp (white, peloric) results in F1 generation: RP x rp = RrPp
06

Phenotype of F1 generation

So, the F1 genotype is RrPp, which results in pink (due to incomplete dominance) and personate phenotype. This matches with the given F1 phenotypes: all pink, personate. Now, let's find the phenotypic ratios resulting from crossing the F1 of (a) to the F1 of (b). (c) Crossing F1 of (a) and F1 of (b) --------------------------------------------------------------------------
07

Crossing F1 generations

Both the F1 generations of (a) and (b) have the same genotype, RrPp (pink, personate). So, we need to find the result of crossing RrPp × RrPp.
08

Determine all possible offspring genotypes

We can use a Punnett square to determine the possible offspring genotypes. The square will have 16 possible results which include: RRPP, RRPp, RrPP, RrPp (1 red, personate; 1 red, peloric; 1 pink, personate; 1 pink, peloric) rrPP, rrPp (1 white, personate; 1 white, peloric)
09

Phenotypic ratios

Based on these results, the phenotypic ratios for a cross between F1 of (a) and F1 of (b) are: 1 red personate : 1 red peloric : 1 pink personate : 1 pink peloric : 1 white personate : 1 white peloric

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Most popular questions from this chapter

A husband and wife have normal vision, although both of their fathers are red- green color-blind, an inherited X-linked recessive condition. What is the probability that their first child will be (a) a normal son? (b) a normal daughter? (c) a color-blind son? (d) a color- blind daughter?

In humans, the \(A B O\) blood type is under the control of autosomal multiple alleles. Color blindness is a recessive X-linked trait. If two parents who are both type \(A\) and have normal vision produce a son who is color-blind and is type \(\mathrm{O},\) what is the probability that their next child will be a female who has normal vision and is type \(\mathrm{O} ?\)

When summer squash plants (Cucurbita pepo) with discshaped fruits are crossed to ones with long fruits, the \(\mathrm{F}_{1}\) generation all have disc-shaped fruits. When the \(F_{1}\) plants are crossed to each other, the \(\mathrm{F}_{2}\) produce spherical fruits as well as exhibit the two parental strains. The phenotypic ratio is 9: 6: 1 (disc-shaped:spherical:long). (a) Which type of gene interaction is this an example of? (b) Explain the phenotypes observed in terms of the number of gene pairs involved and by designating genotypes for all the fruit shapes in the cross. (Use dashes where required.)

In goats, the development of the beard is due to a recessive gene. The following cross involving true-breeding goats was made and carried to the \(\mathrm{F}_{2}\) generation: Offer an explanation for the inheritance and expression of this trait, diagramming the cross. Propose one or more crosses to test your hypothesis.

What is meant by the term epistasis? Distinguish between epis tasis and dominance. Do not use examples in answering this question.

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