Concept explainers
Videos
Which of the following traits would you expect to be inherited as quantitative traits?
a. body weight in chickens
b. growth rate in sheep
c. milk production in cattle
d. fruit weight in tomatoes
e. coat color in dogs
To analyze:
Determine the expected quantitative traits from the following:
Body weight in chicken
Growth rate in sheep
Milk production in cattle
Fruits weight in tomatoes
Coat color in dogs
Introduction:
Multifactorial traits are the results of genetic and non-genetic variation that can contribute to the variation in phenotypes of certain traits. These multifactorial traits can be classified as quantitative traits or qualitative traits. Qualitative phenotypic variations are discontinuous variation whereas quantitative phenotypic variations are continuous variation. The effect of multiple genes which exerts same or different amount of influence on the phenotypes leads to the continuous variation in the phenotypes of polygenic traits. The influence of multiple genes leads to a number of traits called polygenic traits. The incremental contributions by multiple genes result in continuous phenotypic variation. These multiple genes are called additive genes and their effects are called additive gene effects.
Explanation of Solution
The additive effects of multiple genes contribute to the body weight of the chicken. But chickens have different body mass which suggests that each gene contributes a certain quantity of body weight. This difference in body mass is responsible for continuous variation. Therefore, it is a quantitative trait.
Continuous variation is also seen in the growth rate of sheep. The additive effect of multiple genes is responsible for different growth rates. So, the growth rate in sheep is a quantitative trait.
The amount of milk produced by each cattle is varying continuously. This suggests that the phenotypic trait is controlled by a number of genes. Each gene may add a certain quantity of milk. Therefore, milk production in cattle is a quantitative trait.
Tomatoes are also have different weights. This difference in the weight of tomatoes is contributed by different genes. This suggests that continuous variation in weight difference is an additive gene effect. Therefore, fruit weight in tomatoes is a quantitative trait.
It is observed that the coat color of the dogs is not continuously varied. Contrast is present in the coat color of dogs. Therefore, coat color in dogs is not a quantitative trait.
The quantitative traits are classified based on continuous and discontinuous phenotypic variation.
Want to see more full solutions like this?
Chapter 19 Solutions
Study Guide And Solutions Manual For Genetic Analysis: An Integrated Approach
Additional Science Textbook Solutions
Human Anatomy & Physiology
Study Guide for Campbell Biology
Human Biology: Concepts and Current Issues
Human Anatomy & Physiology (11th Edition)
Campbell Biology in Focus (2nd Edition)
Essentials of Genetics (9th Edition) - Standalone book
- In a large population, dairy cows were selected for high milk production. What do you expect to happen with the genes affecting milk production? Do you expect to see a higher or lower variability of alleles after several years of selection?arrow_forwardIn a population of squirrels in North Carolina, the heritability forbody weight is high. This means thata. body weight is primarily controlled by genes.b. the environment has little influence on body weight.c. the variance in body weight is mostly due to genetic variation.d. both a and b are correct.arrow_forwardA genetics researcher determines that the broad-sense heritability of height among Southwestern University undergraduate students is 0.90. Which of the following conclusions would be reasonable? Explain your answer. a. Sally is a Southwestern University undergraduate student, so 10% of her height is determined by nongenetic factors. b. Ninety percent of variation in height among all undergraduate students in the United States is due to genetic differences. c. Ninety percent of the height of Southwestern University undergraduate students is determined by genes. d. Ten percent of the variation in height among Southwestern University undergraduate students is determined by variation in nongenetic factors. e. Because the heritability of height among Southwestern University students is so high, any change in the students’ environment will have minimal effect on their height.arrow_forward
- You perform an adoption study and you determine that for the trait observed there is a strong genetic effect. This is because you observed _______. A. similarities between the adoptees and their sibblings B. similarities between adoptees and adoptive parents C. similarites between adoptees, biological parents, and adoptive parents D. similarities between adoptees and biological parentsarrow_forwardA farmer only breeds cows that produce a lot of milk. This is because the farmer wants more cows that will produce more milk. In this case, who or what is the controlling agent that determines whether certain traits are passed to future generations? a the environment b the farmer c the milk d the cowsarrow_forwardA population of mice contains 20 animals Show work here: with white tails and 30 animals with grey tails. Grey tails are the dominant trait. a. What is the frequency of the white allele? b. What is the frequency of the grey allele? c. What is the frequency of heterozygotes? d. What is the frequency of mice homozygous for the grey allele?arrow_forward
- Which of the following is not an example of a trait that has more than two variations? a eye color b handedness c freckles d ability to roll tonguearrow_forwardWhich of the following statements about dominant traits is correct? a. The dominant trait is the one that is expressed. b. They are observed three-fourths as frequently as heterozygous traits. c. They are observed less frequently than recessive traits. d. They increase in frequency over evolutionary time. e. The dominant trait is typically masked by the recessive trait.arrow_forwardIf a dominant trait shows a penetrance of 50%, then ___. A. All affected individuals in the population are heterozygotes. B. Individuals who have the gene show an intermediate trait. C. Half the individuals in the population have the gene. D. Half the individuals in the population who have the gene show the trait.arrow_forward
- Is each of the following examples due to directional, disruptive, balancing, or stabilizing selection? A. Polymorphisms in snail color and banding pattern as described. B. Thick fur among mammals exposed to cold climates C. Birth weight in humans D. Sturdy stems and leaves among plants exposed to windy climatesarrow_forwardWhich of the following is the MOST important characteristic of a trait for it to undergo descent with modification? A. It must be heritable. B. It must exhibit variation. C. It must exhibit phenotypic plasticity. D. Variation in the trait must be accompanied by variation in fitness.arrow_forwardWhich of the following is an example of environmental impacts on the expression of traits? Heterozygous individuals of a plant species have pink flowers, whereas homozygous individuals have either red or white flowers. An individual’s blood type depends on the interaction of the alleles A, B, or O. Animal coat color shifts in response to seasonal changes in day length and temperature.arrow_forward
Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning