Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 25 - Quantitative Genetics and Multifactorial Traits
Klug - Concepts of Genetics  12th Edition
Klug12th EditionConcepts of Genetics ISBN: 9780135564776Not the one you use?Change textbook
Chapter 25, Problem 26

Consider a true-breeding plant, AABBCC, crossed with another true-breeding plant, aabbcc, whose resulting offspring are AaBbCc. If you cross the F₁ generation, and independent assortment is operational, the expected fraction of offspring in each phenotypic class is given by the expression N!/M!(N−M)! where N is the total number of alleles (six in this example) and M is the number of uppercase alleles. In a cross of AaBbCc×AaBbCc, what proportion of the offspring would be expected to contain two uppercase alleles?

Verified step by step guidance
1
Identify the genotypes of the F₁ generation: AaBbCc.
Determine the possible combinations of alleles for each gene: A/a, B/b, C/c.
Calculate the total number of alleles (N) involved in the cross: 6 alleles (2 for each gene).
Determine the number of uppercase alleles (M) needed: 2 uppercase alleles.
Use the binomial coefficient formula N!/M!(N−M)! to calculate the number of ways to choose 2 uppercase alleles from 6 total alleles.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations based on the principles established by Gregor Mendel. It includes concepts such as dominant and recessive alleles, genotype, and phenotype. In this context, understanding how alleles segregate and assort independently during gamete formation is crucial for predicting offspring traits.
Recommended video:
Guided course
03:45
Descriptive Genetics

Independent Assortment

Independent assortment is a principle stating that alleles for different traits segregate independently of one another during gamete formation. This means that the inheritance of one trait does not affect the inheritance of another. In the given question, this principle allows us to calculate the expected proportions of offspring phenotypes when crossing two heterozygous plants.
Recommended video:
Guided course
04:58
Gamete Genetics and Independent Assortment

Binomial Probability

Binomial probability is a statistical method used to determine the likelihood of a certain number of successes in a fixed number of trials, given a constant probability of success. In the context of the genetic cross, it helps calculate the expected proportion of offspring with specific combinations of alleles, such as two uppercase alleles, by applying the binomial formula to the outcomes of the cross.
Recommended video:
Related Practice
Textbook Question

In a series of crosses between two true-breeding strains of peaches, the F₁ generation was uniform, producing 30-g peaches. The F₂ fruit mass ranges from 38 to 22 g at intervals of 2 g.

Using these data, determine the number of polygenic loci involved in the inheritance of peach mass.

683
views
Textbook Question

In a series of crosses between two true-breeding strains of peaches, the F₁ generation was uniform, producing 30-g peaches. The F₂ fruit mass ranges from 38 to 22 g at intervals of 2 g.

Using gene symbols of your choice, give the genotypes of the parents and the F₂.

608
views
Textbook Question

Students in a genetics laboratory began an experiment in an attempt to increase heat tolerance in two strains of Drosophila melanogaster. One strain was trapped from the wild six weeks before the experiment was to begin; the other was obtained from a Drosophila repository at a university laboratory. In which strain would you expect to see the most rapid and extensive response to heat-tolerance selection, and why?

512
views
Textbook Question

Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in a modified form and content.

Considering that differences in control values represent year-to-year differences in greenhouse conditions, calculate (in mm) the average response to selection over the three-year period

421
views
Textbook Question

Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in modified form and content.

Considering that differences in control values represent year-to-year differences in greenhouse conditions, calculate (in mm) the average response to selection over the three-year period. 

429
views
Textbook Question

Floral traits in plants often play key roles in diversification, in that slight modifications of those traits, if genetically determined, may quickly lead to reproductive restrictions and evolution. Insight into genetic involvement in flower formation is often acquired through selection experiments that expose realized heritability. Lendvai and Levin (2003) conducted a series of artificial selection experiments on flower size (diameter) in Phlox drummondii. Data from their selection experiments are presented in the following table in modified form and content.

Calculate the realized heritability for each year and the overall realized heritability. 

488
views