/*! 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 6 Which of the following is the st... [FREE SOLUTION] | 91影视

91影视

Log out

Learning Materials

Features

Discover

Chapter 14: Problem 6

Which of the following is the strongest evidence that a trait might be influenced by polygenic inheritance? a. \(\mathrm{F}_{1}\) offspring of parents with different phenotypes have an intermediate phenotype. b. \(\mathrm{F}_{1}\) offspring of parents with different phenotypes have the dominant phenotype. c. The trait shows qualitative (discrete) variation. d. 'The trait shows quantitative variation.

Short Answer

Expert verified
d. The trait shows quantitative variation.

Step by step solution

01

Option a: Intermediate phenotype

This option suggests that F1 offspring between parents with different phenotypes display a phenotype that is intermediate between the parent phenotypes. Though this can sometimes be an indication of incomplete dominance, it does not necessarily provide strong evidence for polygenic inheritance. So, this option is not the strongest evidence.
02

Option b: Dominant phenotype

This option indicates that F1 offspring of parents with different phenotypes show the dominant phenotype. This is more characteristic of simple Mendelian inheritance, where one gene controls the trait and there is a clear dominant and recessive allele. Therefore, this option also does not provide strong evidence for polygenic inheritance.
03

Option c: Qualitative variation

This option suggests that the trait shows qualitative or discrete variation. As mentioned in the analysis, qualitative variation is more characteristic of traits controlled by single genes, and polygenic inheritance typically shows quantitative variation. So, this option is not the strongest evidence either.
04

Option d: Quantitative variation

The final option states that the trait shows quantitative or continuous variation. This is characteristic of polygenic inheritance, where multiple genes control a single trait, resulting in a wider range of possible phenotypes. Thus, this option provides the strongest evidence that the trait may be influenced by polygenic inheritance. To summarize, the strongest evidence that a trait might be influenced by polygenic inheritance is:
05

Answer

d. The trait shows quantitative variation.

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.

Quantitative Variation
Quantitative variation is a key feature of polygenic inheritance, where a single trait is influenced by multiple genes. This results in a continuous range of phenotypes, like varying heights in humans or different kernel colors in corn. Instead of distinct categories, quantitative traits exhibit a spectrum, like shades of a color.
These traits are measured rather than categorized, which is why you might find them described by numbers (e.g., height in centimeters) instead of divisions like tall or short. Each gene involved in a polygenic trait contributes a small amount to the phenotype. Therefore, the more genes involved, the greater the range of phenotypes observed.
  • Examples of quantitative traits: height, skin color, intelligence, and weight.
  • Evaluated using statistical methods, as these traits typically follow a bell-shaped distribution known as the normal distribution.
Intermediate Phenotype
An intermediate phenotype occurs when the offspring exhibit a trait that is a mix between their parents' phenotypes. This is typical in cases of incomplete dominance, a different genetic phenomenon that can sometimes be confused with polygenic inheritance.
In incomplete dominance, neither allele is completely dominant over the other, resulting in a blending of traits. However, intermediate phenotypes are not definitive proof of polygenic inheritance.
  • Intermediate phenotypes demonstrate a partial expression of alleles.
  • Example: A red flower crossed with a white flower may produce pink offspring.
Understanding the difference between incomplete dominance and polygenic inheritance is crucial, as multiple genes influence polygenic traits rather than just two alleles.
Mendelian Inheritance
Mendelian inheritance describes how traits are passed from parents to offspring through distinct alleles, either dominant or recessive. Named after Gregor Mendel, who discovered these patterns of inheritance, it is a simpler form of genetic crossing compared to polygenic inheritance.
In Mendelian inheritance:
  • Traits are determined by single genes.
  • There is a clear ratio in offspring phenotypes, often seen in a 3:1 pattern for dominant to recessive traits.
Traits that follow Mendelian inheritance usually show qualitative variation, where there are distinct phenotypic categories such as color or shape. This contrasts with the continuous variation seen in polygenic inheritance.
Qualitative Variation
Qualitative variation represents traits that appear in distinct, separate categories without continuous variation. This is typical for traits governed by Mendelian inheritance, where a single gene determines the trait. These traits are often easy to categorize, like having a specific blood type or a particular flower color.
Qualitative traits do not form a gradient; they are either present or absent. For instance, a plant is either tall or short according to traditional Mendelian concepts.
  • Examples include flower color (red or white) and earlobe attachment (attached or free).
  • Unlike quantitative traits, these don't follow a normal distribution and are more predictable and straightforward.
Understanding the distinction between qualitative and quantitative variations is key in genetics, helping differentiate between single-gene and multi-gene influences on traits.

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

Imagine that a woman is heterozygous for a color blindness allele. At a site on the chromosome with the color blindness allele, a new mutation occurs that causes ALD, creating one chromosome with an allele for color blindness and an allele for ALD. A son of this woman is color-blind but does not have ALD. Assuming that no new mutations have occurred, what could account for this color-blind son without ALD?

Two black female mice are crossed with a brown male. In several litters, female I produced 9 black offspring and 7 brown; female II produced 57 black offspring. What deductions can you make about the inheritance of black and brown coat color in mice? What are the genotypes of the parents in this case?

In flies, small wings are recessive to normal wings. If a cross between two flies produces 8 small wing offspring and 28 normal wing offspring, what are the most likely genotypes of the parents? (Use \(S\) to represent the normal wing allele and \(s\) to represent the short wing allele.)

The alleles found in haploid organisms cannot be dominant or recessive. Why? a. Dominance and recessiveness describe which of two possible phenotypes are exhibited when two different alleles occur in the same individual. b. Because only one allele is present, alleles in haploid organisms are always dominant. c. Alleles in haploid individuals are transmitted like mitochondrial DNA or chloroplast DNA. d. Most haploid individuals are bacteria, and bacterial genetics is completely different from eukaryotic genetics.

When Sutton and Boveri published the chromosome theory of inheritance, research on meiosis had not yet established that paternal and maternal homologs of different chromosomes assort independently. Then, in 1913 , Elinor Carothers published a paper about a grasshopper species with an unusual karyotype: One chromosome had no homolog (meaning no pairing partner at meiosis \(\mathrm{I}\); another chromosome had homologs that could be distinguished under the light microscope. If chromosomes assort independently, how often should Carothers have observed each of the four products of meiosis shown in the following figure? a. Only the gametes with one of each type of chromosome would occur. b. The four types of gametes should be observed to occur at equal frequencies. c. The chromosome with no pairing partner would disintegrate, so only gametes with one copy of the other chromosome would be observed. d. Gametes with one of each type of chromosome would occur twice as often as gametes with just one chromosome.
See all solutions

Recommended explanations on Biology Textbooks

Cellular Energetics

Read Explanation

Plant Biology

Read Explanation

Ecosystems

Read Explanation

Control of Gene Expression

Read Explanation

Biological Organisms

Read Explanation

Biology Experiments

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.