Genetic Analysis: An Integrated Approach (2nd Edition)
2nd Edition
ISBN: 9780321948908
Author: Mark F. Sanders, John L. Bowman
Publisher: PEARSON
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Chapter 21, Problem 25P
Answer the following in regard to multifactorial traits in human twins.
a. If the trait is substantially influenced by genes, would you expect the concordance rate to be higher in MZ twins or higher in DZ twins? Explain your reasoning.
b. If the trait is produced with little contribution from
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Suppose that a geneticist studies a series of characteristics in monozygotic twins and dizygotic twins. He finds various rates of
phenotypic concordance for the characteristics, as shown in the table.
Rate of phenotypic concordance (%)
Characteristic
Monozygotic
Dizygotic
migraine headache
60
30
eye color
100
40
measles
90
90
clubfoot
30
10
high blood pressure
70
40
handedness
70
70
tuberculosis
Classify each characteristic according to whether the corresponding rates of concordance indicate a genetic influence, an
environmental influence, or both genetic and environmental influences.
In a species of fish, the allele for long fins (F) is dominant over the allele for short fins (f). What will be the genotype and phenotype ratios for offspring do we get if we cross a long-finned homozygous male fish with heterozygous long-finned female fish?
Questions:
a. What are the possible genotypes of the egg the woman can produce?
b. What are the possible genotypes of the sperm the man can produce?
c. What is the genotype ratio for the offspring?
d. What is the phenotype ratio for the offspring?
Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci R, S, T, and U and that environmental effects are negligible. Instead of additive versus nonadditive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute two units, and partially additive alleles contribute one unit to height. (a) Can two individuals of moderate height produce offspring that are much taller or shorter than either parent? If so, how? (b) If an individual with the minimum height specified by these genes marries an individual of intermediate or moderate height, will any of their children be taller than the tall parent? Why or why not?
Chapter 21 Solutions
Genetic Analysis: An Integrated Approach (2nd Edition)
Ch. 21 - Which of the following traits would you expect to...Ch. 21 - 19.2 For the traits listed in the previous...Ch. 21 - Compare and contrast broad sense heritability and...Ch. 21 - 19.4 In a cross of two pure-breeding lines of...Ch. 21 - 19.5 Describe the difference between continuous...Ch. 21 - Prob. 6PCh. 21 - 19.7 Provide a definition and an example for each...Ch. 21 - 19.10 Three pairs of genes with two alleles each (...Ch. 21 - Prob. 9PCh. 21 - 19.12 Two inbred lines of sunflowers produce...
Ch. 21 - Prob. 11PCh. 21 - 19.14 In Nicotiana, two inbred strains produce...Ch. 21 - 19.15 Suppose the length of maize ears has narrow...Ch. 21 - In a line of cherry tomatoes, the average fruit...Ch. 21 - 19.17 Two purebreeding wheat strains, one...Ch. 21 - Prob. 16PCh. 21 - During a visit with your grandparents, they...Ch. 21 - 19.20 An association of racehorse owners is...Ch. 21 - Prob. 19PCh. 21 - Suppose a polygenic system for producing color in...Ch. 21 - New Zealand lamb breeders measure the following...Ch. 21 - Cattle breeders would like to improve the protein...Ch. 21 - In human gestational development, abnormalities of...Ch. 21 - The children of couples in which one partner has...Ch. 21 - Answer the following in regard to multifactorial...
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- Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci R, S, T, and U and that environmental effects are negligible. Instead of additive versus non-additive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute 2 units, and partially additive alleles contribute 1 unit to height. Can two individuals of moderate height produce offspring that are much taller or shorter than either parent? What is the percentage of offspring which manifest transgressive variation? Express answer in percentage form. Significant # of decimal places for answer: 2arrow_forwardAssume that the concordance value for a particular trait is 85% for both monozygotic and dizygotic twins. What can be concluded about this trait? ○ It is caused by environmental factors in dizygotic twins but by genetic factors in monozygotic twins. It is likely caused almost exclusively by genetic factors. It is caused by both genetic factors and environmental factors. It is likely caused almost exclusively by environmental factors. It is caused by genetic factors in dizygotic twins but by environmental factors in monozygotic twins. Incorrectarrow_forwardList any phenotypes (e.g., physical or behavioral) that might differ between the average person who is a twin and the average person who is a singleton. Explain your answer (provide an external source, if possible). For most phenotypes, are twins representative of the general population? Why or why not? Do you think the experience of being an MZ twin is very different from being a DZ twin? In which ways?arrow_forward
- please solve all: a) In a hot environment, what do you expect to happen to the allele frequencies? Please explain your answer in 1-2 sentences. b) In a cold environment, what do you expect to happen to the allele frequencies? Please explain your answer in 1-2 sentences. c) If the environment fluctuates between hot and cold (spending half of the time in each condition), what do you expect to happen to the allele frequencies? Please explain your answer in 1-2 sentences.arrow_forwardIdentify each of the following as an example of allele, genotype, and/or phenotype frequency: A. Approximately 1 in 2500 people of Northern European descent is born with cystic fibrosis. B. The percentage of carriers of the sickle cell allele in West Africa is approximately 13%. C. The number of new mutations for achondroplasia, a genetic disorder, is approximately 5 × 10–5.arrow_forwardCystic fibrosis (CF) is a recessive autosomal disorder. In certainpopulations of Northern European descent, the number of peopleborn with this disorder is about 1 in 2500. Assuming Hardy-Weinberg equilibrium for this trait:A. What are the frequencies for the common (non-disease-causing)allele and the mutant (disease-causing) allele.B. What are the genotype frequencies of homozygous unaffected,heterozygous, and homozygous affected individuals?C. Assuming random mating, what is the probability that twophenotypically unaffected heterozygous carriers will chooseeach other as mates?arrow_forward
- Many researchers have estimated the heritability of human traits by comparing the correlation coefficients of monozygotic and dizygotic twins (see pp. 731–732). One of the assumptions made in using this method is that monozygotic twin pairs experience environments that are no more similar to each other than those experienced by dizygotic twin pairs. How might this assumption be violated? Give some specific examples of how the environments of two monozygotic twins might be more similar than the environments of two dizygotic twins.arrow_forwardGiven that there is a trait determined by the alleles A and a, where A is dominant, i.e., the presence of A determines the phenotype. Assume that two parents have four children, and assume that nothing is known about the parents. One of the four children shows the recessive condition (so its genotype is aa) and the other three show the dominant trait (so their genotype is either Aa or AA). What can we conclude about the parents? Group of answer choices - at least one parent shows the dominant trait - Both parents are heterozygous - Both parents have at least one recessive allelearrow_forward.A) To determine if a human trait is heritable, we would best study Group of answer choices. I think it's A. Please explain your answer I'm trying to understand the material a. monozygotic twins that were raised separately, in different environments. b. monozygotic twins that have been raised under similar conditions. c.only distantly related individuals. d. all males or all females. B). To say that a trait exhibits “high heritability” is to say that a. a given set of genes has no influence on a trait. b. there is no difference in genotype between members of the population at the loci in question. c. in a given environment and population, genetic differences have a high degree of influence on the trait compared to environmental influences. d. there is no difference in character between two individuals with the same genotype in question. C). If two populations with identical genetic makeup are raised in different environments, the narrow-sense heritability of a trait of…arrow_forward
- Assume that hair color, hair line, and skin tone in humans are different traits that are controlled by independently-assorting genes. Brown hair (B) is dominant to blond hair (b), a widow’s peak (W) is dominant to a straight hairline (w), and freckles (F) are dominant to no freckles (f). What is the likelihood that the child of a BBWwff person and a bbwwFF person will have: brown hair, a widow’s peak, and freckles? There is no missing information, just have to set up the punet square and I'm not sure how to do all traits.arrow_forwardNote that your Punnett Squares predictions assumed the law of independent assortment was true for these characteristics . How do the percentages of purple smooth , purple wrinkled , yellow smooth , and yellow wrinkled kernels on the cob ( # 9 ) compare to those predicted in # 8 ? Given these results , do the alleles for corn kernel color and shape segregate independently or are they linked ?arrow_forwardYou are studying three traits in a goldfish variety; body colour (A or a), tail length (B or b) and shape (C or c). Note: Use the uppercase letters for the alleles associated with the dominant phenotypes and the lowercase letters for the alleles associated with the recessive phenotypes. Assume that each of these traits is regulated by one gene. a) You mate a gold fish (P1) with a white fish (P2) and obtain 100 fish in F1, of which 50 are gold and 50 are white. Write two sets of the possible genotypes of the parental and the resulting F1 fish by filling in the table below. Sets P1 P2 F1 gold fish F1 white fish AA aA aa A BB ac CC AC ab 2.arrow_forward
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