Concept explainers
EVOLUTION CONNECTION Over the past half century, there has been a trend in the United States and other developed countries for people to marry and Start families later in life than did their parents and grandparents. What effects might this trend have on the incidence (frequency) of late-acting dominant lethal alleles in the population?
Want to see the full answer?
Check out a sample textbook solutionChapter 14 Solutions
Campbell Biology & Alkaline Vents Supplemental Materials for Campbell Biology & Mastering Biology with Pearson eText -- ValuePack Access Card -- for Campbell Biology Package
Additional Science Textbook Solutions
Campbell Biology: Concepts & Connections (9th Edition)
Microbiology with Diseases by Body System (5th Edition)
Genetic Analysis: An Integrated Approach (2nd Edition)
Genetics: Analysis and Principles
Human Biology: Concepts and Current Issues
Microbiology: Principles and Explorations
- Natural Selection Affects the Frequency of Genetic Disorders Will a recessive allele that is lethal in the homozygous condition ever be completely removed from a large population by natural selection?arrow_forwardEVOLUTION LINK Darwins theory of evolution by natural selection is based on four observations about the natural world. One of them is that each individual has a combination of traits that makes it uniquely different. Darwin recognized that much of this variation among individuals must be inherited, but he did not know about Mendels mechanism of inheritance. Based on what you have learned in this chapter, briefly explain the variation among individuals that Darwin observed.arrow_forwardThe allele for long whiskers in mice is dominant over the allele for a short whiskers. In a population of 500 individuals, 25% show the recessive phenotype. How many mice would you expect to be homozygous dominant and heterozygous for the trait?arrow_forward
- 1. Honeybee workers undergo a resistant behavioral pattern called hygienic behavior. Susceptible worker genotypes failed to remove the diseased larvae, so that the disease spread easily throughout the honeybee colony. a) When inbred lines of resistant genotypes were crossed with inbred lines of susceptible genotypes, the F1 worker bees showed unhygienic behavior.Is hygienic behavior dominant or recessive in these bees? Why?arrow_forwardGenes and inheritance have an impact on the lives of parents and their progeny, the F1 and F2 generations. Population genetics also deals with genetics, but in a different way. What is the definition of population genetics? How can the abundance of an allele be different in a population as compared with an individual of the population? (Hint: How can the phenotype of a population differ from that of an individual? Can a population have red flowers, pink flowers, and white flowers? Can one individual have all three types of flowers?)arrow_forwardACTIVITY 3: Incomplete dominance vs. codominance  Coat color in dragons is controlled by 2 alleles.  A black dragon is crossed with a white dragon and all of the offspring are gray. Are the alleles incompletely dominant or codominant? ___ Explain (how do you know)? What would offspring of the other type probably look like?  __arrow_forward
- Evolution takes place through a combination of mechanisms at the level of populations. This process consists of a change in allele frequencies in a population over time. Consider the following scenario: You are observing a population of wild mice that has a dominant allele which produces white-colored fur, while the homozygous recessive alleles result in dark brown fur. Genetic studies have indicated that this gene for fur color follows Mendelian inheritance. Originally, the mice population was comprised of over 80% of white mice in a dark forest environment. As the local fox population increased, you noticed that there were fewer white mice and more brown-colored mice. By the end of your observation period of six months, you notice that brown-colored mice now make up over 60% of the total mice population. Based on this scenario, explain what force of evolution is at workarrow_forwardEvolution takes place through a combination of mechanisms at the level of populations. This process consists of a change in allele frequencies in a population over time. Consider the following scenario: You are observing a population of wild mice that has a dominant allele which produces white-colored fur, while the homozygous recessive alleles result in dark brown fur. Genetic studies have indicated that this gene for fur color follows Mendelian inheritance. Originally, the mice population was comprised of over 80% of white mice in a dark forest environment. As the local fox population increased, you noticed that there were fewer white mice and more brown-colored mice. By the end of your observation period of six months, you notice that brown-colored mice now make up over 60% of the total mice population. 1. Based on this scenario, explain what force of evolution is at work. 2. Are you observing microevolution or macroevolution? Explain your answer.arrow_forwardDarwin’s insights into the role of selection in evolution began with close observations of the enormous phenotypic variation among different pure-breeding varieties of domesticated pigeons. Study of varieties found in any domesticated species could provide similar insights. For comparison, we’d like to know what degree of phenotypic variation might be expected among the domesticated peas available to Mendel.a. Starting with an F1 hybrid heterozygous for phenotypically distinguishable allele pairs (one of which is completely dominant to the other) at 7 genes, how many different phenotypes would be expected in the F2 generation?b. It might take a large number of F2 individuals to observe all of these phenotypic combinations, depending on the frequency of the rarest phenotype. What is the expected rarest phenotype and what it its expected frequency among the F2 individuals?c. How many different phenotypes could have been observed in the F2 generation if all of the allele pairs of the 7…arrow_forward
- Heterozygote advantage is an interesting condition in those individuals who have one of each allele (dominant and recessive) have a higher survival rate than those individuals who are either homozygous dominant or homozygous recessive. Sickle-cell anemia is such a genetic disease associated with the recessive allele. Normal homozygous individuals (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to…arrow_forwardDarwin’s insights into the role of selection in evolution began with close observations of the enormous phenotypic variation among different pure-breeding varieties of domesticated pigeons. Study of varieties found in any domesticated species could provide similar insights. For comparison, we’d like to know what degree of phenotypic variation might be expected among the domesticated peas available to Mendel.d. In the F10 generation from the above hybrid, how many phenotypically distinguishable pure-breeding varieties could be observed? [part c was 2187]e. [Note: this one requires use of combinations; it is also a significantly more difficult problem.] Mendel began his work with pairs of varieties from the breeders that differed from each other in just one trait (corresponding to one gene difference, as we now know) out of the 7 traits he studied. These pairs could be obtained by self-pollinating an individual from an advanced generation that was pure-breeding for 6 of the traits but…arrow_forwardColor blindness in humans is an X-linked recessive trait. Approximately10% of the men in a particular population are color blind.a. If mating is random with respect to the color-blindness locus, what isthe frequency of the color-blindness allele in this population?b. What proportion of the women in this population are expected to becolor blind?c. What proportion of the women in this population are expected to beheterozygous carriers of the color-blindness allele?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage LearningBiology (MindTap Course List)BiologyISBN:9781337392938Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. BergPublisher:Cengage Learning