/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 34 The frizzle fowl is much admired... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 6: Problem 34

The frizzle fowl is much admired by poultry fanciers. It gets its name from the unusual way that its feathers curl up, giving the impression that it has been (in the memorable words of animal geneticist \(\mathrm{F}\) B. Hutt) "pulled backwards through a knothole." Unfortunately, frizzle fowl do not breed true: when two frizzles are intercrossed, they always produce 50 percent frizzles, 25 percent normal, and 25 percent with peculiar woolly feathers that soon fall out, leaving the birds naked. a. Give a genetic explanation for these results, showing genotypes of all phenotypes, and provide a statement of how your explanation works. b. If you wanted to mass-produce frizzle fowl for sale, which types would be best to use as a breeding pair?

Short Answer

Expert verified
Frizzle fowls show incomplete dominance. Use two frizzle fowls (\(FN\)) for breeding to produce 50% frizzle offspring.

Step by step solution

01

Analyzing the Phenotype Ratios

When two frizzle fowls are crossed, the offspring are produced in the ratios of 50% frizzles, 25% normal, and 25% with woolly feathers. This 1:2:1 ratio suggests incomplete dominance in the gene responsible for feather type.
02

Assigning Genotypes

The frizzle trait is represented by an incompletely dominant allele \(F\), while the allele for normal feathers is \(N\). Thus, the genotype for frizzle fowls is \(FN\), normal is \(NN\), and woolly is \(FF\). The cross \(FN \times FN\) gives offspring: 25% \(FF\) (woolly), 50% \(FN\) (frizzle), and 25% \(NN\) (normal), matching the phenotype ratios.
03

Explanation of Genetic Outcome

The frizzle gene \(F\) is incompletely dominant over normal \(N\). This incomplete dominance results in frizzle fowls (\(FN\)) having a distinct phenotype from either homozygous condition, normal (\(NN\)) or woolly (\(FF\)). Frizzle fowls (\(FN\)) show a combination of the two traits.
04

Choosing a Breeding Pair for Frizzle Fowls

To mass-produce frizzle fowls, the most effective breeding pair would be two frizzle fowls (\(FN\) and \(FN\)), as they consistently produce 50% frizzle offspring, with the remaining offspring divided between normal and woolly phenotypes.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91影视!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Incomplete Dominance
Incomplete dominance is an important concept in genetics that explains how certain traits appear in the offspring. In this scenario, incomplete dominance is observed in frizzle fowl's feather type. Unlike complete dominance, where a dominant trait completely masks a recessive one, incomplete dominance results in a blend of characteristics from both alleles. For frizzle fowls, the feather characteristic is governed by two alleles: one for the frizzle feathers and one for the normal feathers. When two different alleles are present (as in genotype \( FN \)), neither is fully dominant over the other. This partial expression leads to a unique phenotype known as frizzle feathers, which is distinct from the phenotypes produced by homozygous genotypes like \( FF \) or \( NN \). In this case, the frizzle feather phenotype is expressed as a halfway point between woolly and normal feathers.
Deciphering Phenotype Ratios
Phenotype ratios provide insights into the inheritance patterns of various traits. In the case of frizzle fowls, the offspring of two frizzle parents ( FN \times FN) result in a 1:2:1 ratio of phenotypes, which are:
  • 25% Woolly (\( FF \))
  • 50% Frizzle (\( FN \))
  • 25% Normal (\( NN \))
These ratios are indicative of incomplete dominance at play. The distinct 1:2:1 ratio typically points towards the fact that the heterozygous phenotype (\( FN \)) appears with greater frequency than the homozygous ones due to the mixed expression of both alleles.This specific ratio allows geneticists to predict the possible outcomes when breeding two frizzle fowls. Hence, understanding phenotype ratios helps in breeding strategies to achieve the desired feather type in offspring.
Genotype Explanation Simplified
Genotypes are a genetic blueprint that specifies the traits an organism will display. In the case of the frizzle fowl, three genotypes lead to different phenotypes:
  • \( FF \): Exhibits woolly feathers, as the frizzle gene is expressed completely without the normal gene present.
  • \( FN \): Results in frizzle feathers due to the blend from incomplete dominance. This is because neither allele completely dominates the feather appearance.
  • \( NN \): Displays normal feathers, as it contains only the allele for normal feathering and lacks any frizzle expression.
Thus, the genotype \( FN \) explains the presence of the frizzle feather phenotype, which is neither fully woolly nor normal but a distinct feather type due to incomplete dominance. Understanding these genotypes helps in designing breeding pairs that maximize desirable traits in future generations.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

On a fox ranch in Wisconsin, a mutation arose that gave a "platinum" coat color. The platinum color proved very popular with buyers of fox coats, but the breeders could not develop a pure-breeding platinum strain. Every time two platinums were crossed, some normal foxes appeared in the progeny. For example, the repeated matings of the same pair of platinums produced 82 platinum and 38 normal progeny. All other such matings gave similar progeny ratios. State a concise genetic hypothesis that accounts for these results.

In a maternity ward, four babies become accidentally mixed up. The ABO types of the four babies are known to be \(\mathrm{O}, \mathrm{A}, \mathrm{B},\) and \(\mathrm{AB}\). The \(\mathrm{ABO}\) types of the four sets of parents are determined. Indicate which baby belongs to each set of parents: (a) \(A B \times O,(b) A \times O,(c) A x\) \(\mathrm{AB},(\mathrm{d}) \mathrm{O} \times \mathrm{O}\).

Mice normally have one yellow band on each hair, but variants with two or three bands are known. A female mouse having one band was crossed with a male having three bands. (Neither animal was from a pure line.) The progeny were \(\begin{array}{lll}\text { Females } & \frac{1}{2} \text { one band } & \text { Males } & \frac{1}{2} \text { one band } \\ & \frac{1}{2} \text { three bands } & & \frac{1}{2} \text { two bands }\end{array}\) a. Provide a clear explanation of the inheritance of these phenotypes. b. In accord with your model, what would be the outcome of a cross between a three-banded daughter and a one-banded son?

If a man of blood-group AB marries a woman of bloodgroup A whose father was of blood-group \(\mathrm{O}\), to what different blood groups can this man and woman expect their children to belong?

A yeast geneticist irradiates haploid cells of a strain that is an adenine- requiring auxotrophic mutant, caused by mutation of the gene ade1. Millions of the irradiated cells are plated on minimal medium, and a small number of cells divide and produce prototrophic colonies. These colonies are crossed individually with a wild-type strain. Two types of results are obtained: (1) prototroph \(\times\) wild type:progeny all prototrophic (2) prototroph \(\times\) wild type : progeny \(75 \%\) prototrophic, \(25 \%\) adenine-requiring auxotrophs a. Explain the difference between these two types of results. b. Write the genotypes of the prototrophs in each case. c. What progeny phenotypes and ratios do you predict from crossing a prototroph of type 2 by the original ade1 auxotroph?
See all solutions

Recommended explanations on Biology Textbooks

Microbiology

Read Explanation

Biology Experiments

Read Explanation

Organ Systems

Read Explanation

Chemistry of Life

Read Explanation

Ecosystems

Read Explanation

Control of Gene Expression

Read Explanation
View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.