K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
For each question, select the best answer from the four alternatives.
1. If a true-breeding pea plant with yellow seeds is crossed with a true-breeding pea plant with green seeds, what is the probability that the F1 generation will have green seeds? (5.1) K/U (a) 0 % (b) 25 % (c) 75 % (d) 100 %
2. The hereditary units that Mendel called "factors" are known today as (a) genes (b) traits (c) chromosomes (d) characteristics (5.1) K/U
3. In snapdragons, a cross between a red-flowering snapdragon and a white-flowering snapdragon will produce snapdragons that have pink flowers. This is an example of (a) complete dominance (b) codominance (c) incomplete dominance (d) X-linked dominance (5.2) K/U
4. In humans, the blood type allele IA shows complete dominance when paired with (a) the allele i only (b) the allele IB only (c) the allele i or the allele IB (d) neither the allele i nor the allele IB (5.2) K/U
5. In a pedigree you know a trait is recessive if (a) both parents of the affected individual have the same trait (b) neither parent of the individual has the same trait (c) the mother has the trait but the father does not (d) the father has the trait but the mother does not (5.3) K/U
6. How are Y-linked disorders passed on? (5.3) K/U (a) from father to daughter (b) from father to son (c) from mother to daughter (d) from mother to son
7. Which disorder is a dominant trait? (5.5) K/U (a) cystic fibrosis (b) Tay-Sachs disease (c) hemophilia (d) Huntington's disease
8. Which is the genotype of an individual that could be used in a dihybrid cross? (5.7) K/U (a) RRYY (b) RRYy (c) RrYY (d) RrYy
9. In a family with three children, what is the probability that the first child is a boy, the second child is a girl, and the third child is a boy? (5.7) K/U (a) 12.5 % (b) 25 % (c) 50 % (d) 75 %
Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true.
10. In genetics, the mating of two organisms is called an allele. (5.1) K/U
11. Recessive alleles are expressed only when both alleles are the same. (5.1) K/U
12. An individual's outward appearance for a particular characteristic is his or her phenotype. (5.1) K/U
13. Each parent passes along one allele for each gene. (5.1) K/U
14. A Punnett square is a diagram that can be used to predict the outcome of a cross between two organisms. (5.1) K/U
15. If the chance of event A is 25 % and the chance of event B is 10 %, then the chance of both event A and B occurring is 35 %. (5.1) K/U
16. AB blood type in humans is an example of incomplete dominance. (5.2) K/U
17. On a pedigree chart, an affected female is indicated by a shaded square. (5.3) K/U
18. In autosomal inheritance, males and females are affected equally. (5.3) K/U
19. A trait that occurs in all of the males of a family and none of the females is probably X-linked. (5.3) K/U
20. An individual who is heterozygous for the allele that causes cystic fibrosis is called a carrier. (5.5) K/U
21. Neurofibromatosis is a genetic disorder that is a recessive trait. (5.5) K/U
22. Height is an example of a human characteristic that shows discontinuous variation. (5.7) K/U
23. Skin colour is a human characteristic affected by additive alleles. (5.7) K/U
24. An individual with the genotype RrGG can produce gametes with three different allele combinations. (5.1, 5.7) K/U
To do an online self-quiz, GO TO NELSON SCIENCE
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CHAPTER 5 REVIEW
Key
K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
Knowledge
For each question, select the best answer from the four alternatives.
1. In a cross, the P generation consists of two true-breeding pea plants: one with purple flowers and one with white flowers. How many different genotypes will be present in the F1 generation? (5.1) K/U (a) 1 (b) 2 (c) 3 (d) 4
2. What term describes an individual who carries only one type of allele for a gene? (5.1) K/U (a) heterozygous (b) monohybrid (c) homozygous (d) dihybrid
3. What pattern of heredity is demonstrated when, in shorthorn cattle, a cross between a red bull and a white cow results in roan calves? (5.2) K/U (a) complete dominance (b) codominance (c) incomplete dominance (d) X-linked dominance
4. In humans, which blood type is the result of codominance? (5.2) K/U (a) type A (b) type B (c) type AB (d) type 0
5. A pedigree chart shows two unaffected parents who have two affected offspring and two unaffected offspring. What are the genotypes of the parents for the trait? (5.3) K/U (a) heterozygous (b) homozygous recessive (c) homozygous dominant (d) impossible to determine
6. On a pedigree chart, what symbol indicates an affected male? (5.3) K/U (a) shaded square (b) shaded circle (c) unshaded square (d) unshaded circle
7. How is the probability of two independent events both occurring calculated? (5.7) K/U (a) Multiply the probabilities of the events. (b) Add the probabilities of the events. (c) Subtract the probabilities of the events. (d) Divide the probabilities of the events.
8. What phenotype ratio is expected in a dihybrid cross? (5.7) K/U (a) 3:1 (b) 1:2:1 (c) 9:3:3:1 (d) 3:1:9
Match each term on the left with the most appropriate description on the right
(i) buildup of uric acid in the body (ii) progressive degeneration of the nervous system (iii) inability to digest galactose (iv) inability to form blood clots (v) nerve cells in the brain are affected by the accumulation of gangliosides (5.5) K/U
Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true.
10. The set of alleles an individual has is called its genotype. (5.1) im
11. An allele that is always expressed whenever it is present is a recessive allele. (5.1) K/U
12. When an individual who is heterozygous for a trait has a blended phenotype, this is called codominance. (5.2) K/U
13. For blood type, humans have three different alleles. (5.2) K/U
14. In a pedigree chart, Roman numerals are used to specify generations. (5.3) K/U
15. A disorder that can be passed only from father to son is X-linked. (5.3) K/U
16. Carrier testing is used to identify individuals who carry disorder-causing dominant alleles. (5.5) K/U
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Key
K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
17. If both parents are carriers of cystic fibrosis (CF) but do not have the disease themselves, the probability that they will have a child with CF is 1 in 4. (5.5) K/U
18. Dihybrid crosses can be used to demonstrate the law of independent assortment. (5.7) K/U
Write a short answer to each question.
19. List the seven characteristics of pea plants that Mendel investigated. (5.1) K/U
20. In a monohybrid cross, what ratio of phenotypes would you expect to find in the offspring? (5.1) K/U
21. Define the term "allele!' (5.1) K/U
22. During which stage of meiosis do homologous chromosomes separate? (5.1) K/U
23. List the possible genotypes of the offspring of a cross between an individual with the genotype Hh and another individual with the genotype Hh. (5.1) K/U
24. If a red-flowering snapdragon were crossed with a white-flowering snapdragon, what percentage of the offspring would you expect to be red-flowered? (5.2) K/U
25. Draw a pedigree chart that shows a family with an affected father and an unaffected mother whose children are, in the following order, an unaffected son, an affected daughter, and a second unaffected son. (5.3) K/U
26. Cystic fibrosis causes the body of affected individuals to produce thick, sticky mucus. Identify three specific ways that this affects the body. (5.5) K/U
27. In a family in which both parents are carriers of cystic fibrosis but do not have the disease themselves, what percentage of their offspring would you expect to be carriers of CF but not have the disease? (5.5) K/U
28. In a dihybrid cross, how many possible genotypes can result in the offspring? (5.7) K/U
Understanding
29. Explain why Mendel removed the male reproductive organs in some of the plants used in his investigations. (5.1) K/U
30. (a) Contrast the meaning of the terms "characteristic" and "trait:' (b) Give one example of a human characteristic and one example of a human trait. (5.1) K/U
31. List two characteristics of the garden pea that made it an ideal plant for Mendel to use in his experiments. (5.1) K/U
32. Can an allele that is not expressed in an individual be passed on to that individual's offspring? Explain why or why not. (5.1) K/U T/I
33. An individual is heterozygous. Is her dominant allele more or less likely to be passed on to her offspring than her recessive allele? Explain. (5.1) CM K/U T/I
34. Restate in your own words the two conclusions that form the law of segregation. (5.1) K/U
35. (a) Describe the "blending" theory that was accepted by many scientists at the time Mendel performed his investigations. (b) Explain how Mendel's work disproved this theory. (c) Discuss how the results might have differed if Mendel had worked with snapdragons rather than pea plants. (5.1) K/U
36. Compare and contrast codominance and complete dominance. Identify one way they are similar and one way they are different. (5.2) K/U T/I
37. What scientific advances are responsible for test crosses being performed less often than they used to be? (5.1) K/U T/I
38. A given gene for a codominant trait has multiple alleles. Explain how these multiple alleles can increase the variation in a population. (5.2) K/U T/I
39. A farmer crosses a roan bull and a roan cow. (5.2) K/U T/I (a) What is the expecte genotype ratio of the offspring? (b) What is the expected phenotype ratio of the offspring? (c) What is the probability of an offspring of this cross being red? (d) What is the probability of an offspring of this cross being roan?
40. (a) Compare and contrast a Punnett square and a pedigree chart. Describe one way that they are similar and one way that they are different. (b) Explain how a genetic counsellor could use each of these tools. (5.1, 5.3, 5.5) K/U T/I
41. The analysis of some pedigree charts provides proof that a trait is dominant. Draw an example of a pedigree chart that illustrates this point. (5.3) K/U C
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Key
K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
42. Interpret the pedigree chart in Figure 1. (5.3) T/I A
Figure 1
Image: (I) A square(I-1) and a shaded circle(I-2): mating; (II) A circle(II-1), a shaded circle(II-2)not a sibling connected to a square(II-3), a square(II-4), a square(II-5), a square(II-6) connected to a circle(II-7)not a sibling; (III) Shaded circle(II-2) and square(II-3): mating, are connected by a vertical line to (III) A shaded square(III-1), a circle(III-2), a circle(III-3), and a shaded circle(III-4): siblings; Square(II-6) and circle(II-7): mating, are connected by a vertical line to circle(III-5): child.
(a) How many offspring of the individuals in generation I are shown in the pedigree chart? (b) How many offspring of generation I are affected with the disorder? (c) In generation III, how many affected individuals are shown? (d) Redraw the pedigree to indicate that 11-4 and 11-5 are identical twins. (e) Is the trait controlled by a dominant or a recessive allele? Explain your reasoning. (f) Which individuals must be carriers? (g) Could this trait be X-linked recessive? Explain your reasoning.
43. Individuals who carry out genetic research are usually motivated by scientific curiosity. Explain why Dr. Nancy Wexler had motivation beyond scientific curiosity to investigate Huntington's disease. (5.4) K/U T/I
44. (a) What is a "marker" for a genetic disorder? (b) What is the significance of finding a marker for a genetic disorder, such as Huntington's disease? (c) How have advances in DNA technology furthered research on Huntington's disease? (5.4) K/U
45. (a) Summarize the dietary restrictions recommended for an individual with phenylketonuria (PKU). (b) What are the consequences for an individual with PKU if these restrictions are not followed? (5.5) K/U
46. (a) Describe how genetics can play a role in the development of breast cancer in an individual. (b) Describe how the environment can play a role in the development of breast cancer in an individual. (5.5) K/U
47. (a) Compare and contrast continuous variation and discontinuous variation. (b) Give one example of each type of variation. (5.7) K/U T/I
48. Describe how additive alleles play a role in the great variation of human skin colour. (5.7) K/U
Analysis and Application
49. A test cross was carried out to determine if a bull displaying a dominant trait was heterozygous or homozygous. The alleles for the trait are designated by the letters T and t. The offspring display both dominant and recessive phenotypes. Draw a Punnett square that shows the alleles produced by both parents and the genotypes of the offspring. (5.1) T/I A
50. Assess the importance of each of the following aspects of Mendel's experimental design. Write a sentence for each aspect of Mendel's work, explaining its significance. (5.1) T/I A (a) the use of pea plants (b) the number of pea plants tested (c) recording and analyzing large amounts of data (d) reporting results that differed from the results that were expected
51. In pea plants, inflated pod shape (I) is dominant over constricted pod shape (i). (5.1) T/I A (a) List two genotypes that would result in a phenotype of inflated pods. (b) Identify a genotype that would result in a phenotype of constricted pods. (c) A cross between two pea plants results in 100 % of the offspring having constricted pods. What were the genotypes of the two parent pea plants? (d) Explain how you can be sure of your response to part (c).
52. A child is born with a trait that is not present in either of the child's biological parents. (5.1) T/I C A (a) Is the child's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know? (b) Is the mother's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know? (c) Is the father's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know? (d) The alleles for this trait can be represented with the letters B and b. Draw a Punnett square that shows this cross. In the completed Punnett square, circle the genotype that represents the child described in the question. (e) What is the probability of these parents having another child with the same trait as the child described in the question?
53. How might Mendel's conclusions have differed if he finished his experiment after observing the F1 generation instead of the F2 generation? (5.1) T/I A
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Key
K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
54. In Andalusian chickens, the alleles for feather colour exhibit incomplete dominance. An individual with one allele for black feathers and one allele for white-splashed feathers displays a blue-feather phenotype (Figure 2). (5.2) T/I C A (a) Would a chicken of this variety with black feathers be heterozygous or homozygous? How do you know? (b) Would a chicken of this variety with blue feathers be heterozygous or homozygous? How do you know? (c) If two chickens with blue feathers are crossed, what phenotype or phenotypes will the offspring have?
Figure 2
Image: A chicken with black and white feathers
55. If two roan cattle are crossed, they have a greater likelihood of producing a roan offspring than they do of producing a red offspring or a white offspring. Explain why this is true. (5.2) T/I A
56. A farmer wants to produce only roan cattle on his farm. Should he start with two roan cattle or with one red and one white? Explain your answer. (5.2) T/I A
57. If there was room to stock and carry only one type of blood to use for transfusions in an ambulance, what type of blood should be chosen? Explain your response. (5.2) T/I A
58. A child's biological father has blood type AB. The child's mother does not know her blood type. (5.2) T/I A (a) Using this information, identify three blood types the child could have. (b) Explain how each of these blood types could occur in the child. (c) Identify a blood type that could not be present in the child. Explain your thinking.
59. Apply what you have learned about alleles and variation in a population to explain why finding an appropriate donor for a transplant is typically very difficult. (5.2) T/I A
60. A pedigree chart shows a cross between two unaffected individuals that produces an affected individual. (5.3) K/U (a) Using only this information, is it possible to determine if the trait is dominant or recessive? Explain your thinking. (b) Using only this information, is it possible to determine the genotype of the affected individual? Explain your thinking.
61. Some genetic disorders are classified as X-linked disorders. (5.3) T/I A (a) Explain how X-linked disorders differ from autosomal disorders. (b) Give one example of an X-linked disorder in humans. (c) If an X-linked disorder is recessive, can a male be a carrier of this disorder? Why or why not?
62. (a) If carrier testing is available for a human genetic disorder, is the disorder caused by a dominant allele or a recessive allele? How do you know? (b) Give an example of a disease for which carrier testing is available. (5.5) K/U T/I A
63. A couple is evaluating their chances of having a child born with cystic fibrosis (CF). Both the man and the woman know their family's medical history for the past two generations—there have been no children born with CF. Is it possible for this couple to have a child with CF? Explain why or why not. (5.5) T/I
64. Some adopted individuals have access to their medical histories, while others do not. Explain how the information in this chapter could be applied to argue for the importance of all adopted individuals having access to medical histories of their biological parents. (5.5) T/I C A
65. In genetics, the expected probability of a trait can be calculated. There is typically a difference between the predicted probability and the actual rate of occurrence of the trait in a population. Explain how the size of this difference changes as the size of the observed population increases. (5.7) T/I A
66. Does the law of independent assortment apply to genes located on the same chromosome? Why or why not? (5.7) T/I A
67. In foxes, two alleles, PP and PS, influence survival and hair colour. PPPP zygotes do not survive. PPPS individuals have normal health and platinum coat colour. PSPS individuals also have normal health and have a silver coat. What are the expected genotype and phenotype ratios of offspring from the cross of a platinum and a silver fox? K/U A
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Key
K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
Evaluation
68. When a true-breeding purple pea plant and a true- breeding white pea plant are crossed, the trait of white flowers is not seen in the F1 generation. Some people say that the trait of white flowers "disappears" in the F1 generation. (5.1) T/I C A (a) Evaluate the use of the word "disappears" to describe what occurs. (b) Suggest a term that better reflects what happens to the trait of white flowers. Explain your thinking.
69. It is a common misconception that the traits most commonly seen in a population are dominant traits. However, this is not the case. For example, in humans, freckles are a dominant trait, but they are found in only a small portion of the population. Use this information and the information you have learned about allele frequency to develop an explanation that addresses this misconception. (5.1) T/I C A
70. Evaluate the term "father of genetics:' which has been used to describe Mendel. Explain why this is a fitting description, based on his work. (5.1) T/I C A
71. Would a Punnett square be a useful real-life tool to predict all of the traits of a human child? Write a paragraph that gives two specific reasons why or why not. (5.1) T/I C A
72. Your friend strongly resembles his father but looks very different from his mother. He states that he must have received two alleles for many of his traits from his father and none from his mother. Evaluate your friend's statement. Explain whether it is a good explanation for his resemblance to his father or not. (5.1) T/I C A
73. Imagine you are a geneticist. Which area of research would you be most interested in: developing better genetic screening procedures, developing and testing new treatments, or some other area of research? What factors influenced your choice? (5.5) T/I C A
74. Both genetics and the environment can play roles in the development of breast cancer. Do you think that all women should be screened for defective BRCA1 and BRCA2 genes so they can then use that information to determine how careful they should be regarding certain environmental factors? Explain your response. (5.5) T/I A
75. Your seven-year-old brother has a new classmate who has cystic fibrosis. Your brother states that he does not want to sit next to the new student because he is afraid of catching CF. Evaluate your brother's statement. Identify the misconception your brother has, and write a paragraph to explain to your brother why he should not be concerned about contracting cystic fibrosis from his classmate. (5.5) T/I C A
76. The Ontario Newborn Screening Program checks for certain disorders. Do you think it should be expanded to include disorders that will not appear until much later in life, such as Huntington's disease? Explain your response. (5.5) T/I C A
77. Should individuals have complete control over who accesses the results of any genetic testing they have undergone? Explain your response. (5.6) T/I A
78. A family you know has three boys and no girls. They are expecting their fourth baby. You overhear someone saying that the family is likely to have a girl this time, because they have had three boys already. Is this statement valid? Write a paragraph to explain why. (5.7) T/I C A
Reflect on Your Learning
79. Mendel's work did not yield the results that most scientists of his time would have expected. Even so, he carefully recorded and reported his data. Does learning this information change your feelings about the importance of getting the "expected" results when carrying out an experiment? Why or why not? T/I A
80. After reading the information in this chapter, do you think you will actively seek out carrier testing for cystic fibrosis if you decide to have biological children? Why or why not? T/I A
81. If you could perform medical research in hopes of eradicating one genetic disorder, on what disorder would you focus your research? Explain your choice. T/I A
82. What section of this chapter did you find most interesting? What section contains information that will be most applicable to your life? Explain each of your responses. T/I A
83. If your family history included individuals with Huntington's disease, would you opt for or against genetic testing to determine if you carry the gene? Explain your response. T/I A
Research GO TO NELSON SCIENCE
84. Gregor Mendel's work occurred primarily in the years 1856 to 1866, although the importance of his work was not recognized for many years. Research and write a short report on one other scientific advance, world event, contribution to music or the arts, or other significant event that occurred in this same time period. Share your report with your classmates. T/I C A
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Key K/U: Knowledge and Understanding T/I: Thinking and Investigation C: Communication A: Application
85. Research to learn more about Reginald Punnett, the individual for whom Punnett squares were named. Prepare a short oral report to share what you have learned with your classmates. T/I C A
86. The treatment for the genetic disorder phenylketonuria includes many dietary restrictions. Research these dietary restrictions. Then develop a menu for a day's meals that follow these restrictions. Share your menu with a small group of students. (5.7) T/I C A
87. The Human Genome Project (HGP) was a large-scale project that resulted in the sequencing of the human genome. Research the disease-causing genes that have been located as a result of the work done during the HGP. Prepare a short report that summarizes information about the HGP, and explain how it is related to advances in the treatment or diagnosis of genetic diseases. T/I C A
88. Sickle-cell anemia is a trait caused by a recessive allele. Carriers, who have one sickle-cell allele, have an increased resistance to malaria. Research sickle-cell anemia for information about its symptoms and treatment, the regions where the sickle-cell trait is most common, and how that relates to malaria resistance. Present your findings as a short newspaper-style article. T/I C A
89. A new trend in genetic testing is direct-to-consumer genetic testing. This is genetic testing that does not involve a healthcare provider. An individual purchases a test, provides a sample, and receives the results without a visit to the doctor. Learn more about direct-to-consumer genetic testing and its advantages and disadvantages. Share what you learn in a class-discussion format. Be prepared to state your opinion about whether direct-to-consumer genetic testing is helpful or harmful. T/I C A
90. Duchenne muscular dystrophy is a genetic disorder that affects males. Research the symptoms of this disorder and its mode of inheritance. Prepare four note cards, each with a different specific fact about Duchenne muscular dystrophy. Then discuss this disorder with three other students in a small-group format. Use the information on your note cards in the discussion. After you have shared a fact, pass around the card containing the fact so others can read the information on the card. T/I C A
91. Research to find out more about the Ontario Newborn Screening Program. Locate the list of all conditions that this program screens for. Then select a condition that was not described in this chapter for which screening is performed. Use the resources available through the Newborn Screening website and other reliable websites to find out more about this condition. Make a pamphlet to share what you have learned with others. Your pamphlet must present information in an organized format and include illustrations or diagrams. T/I C A
92. Polycystic kidney disease is a human genetic disorder that affects millions of people worldwide. This disorder has two forms: autosomal dominant and autosomal recessive. Research the symptoms, testing, and treatment for both forms of this disorder. Prepare a short oral report to share what you have learned. T/I C A
93. Early on in the embryonic development of female mammals, one of the X chromosomes in every cell becomes almost entirely inactivated and forms a Barr body. Do research to learn more about the formation of the Barr body and what it means for female Calico cats (Figure 3).
(a) Why are there no male Calico cats? (b) Why are the colour patterns on the females made up of random patches? (c) Are all aspects of their colour influenced by the same alleles?
Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
For each question, select the best answer from the four alternatives.
1. If a true-breeding pea plant with yellow seeds is crossed with a true-breeding pea plant with green seeds, what is the probability that the F1 generation will have green seeds? (5.1) K/U
(a) 0 %
(b) 25 %
(c) 75 %
(d) 100 %
2. The hereditary units that Mendel called "factors" are known today as
(a) genes
(b) traits
(c) chromosomes
(d) characteristics (5.1) K/U
3. In snapdragons, a cross between a red-flowering snapdragon and a white-flowering snapdragon will produce snapdragons that have pink flowers. This is an example of
(a) complete dominance
(b) codominance
(c) incomplete dominance
(d) X-linked dominance (5.2) K/U
4. In humans, the blood type allele IA shows complete dominance when paired with
(a) the allele i only
(b) the allele IB only
(c) the allele i or the allele IB
(d) neither the allele i nor the allele IB (5.2) K/U
5. In a pedigree you know a trait is recessive if
(a) both parents of the affected individual have the same trait
(b) neither parent of the individual has the same trait
(c) the mother has the trait but the father does not
(d) the father has the trait but the mother does not (5.3) K/U
6. How are Y-linked disorders passed on? (5.3) K/U
(a) from father to daughter
(b) from father to son
(c) from mother to daughter
(d) from mother to son
7. Which disorder is a dominant trait? (5.5) K/U
(a) cystic fibrosis
(b) Tay-Sachs disease
(c) hemophilia
(d) Huntington's disease
8. Which is the genotype of an individual that could be used in a dihybrid cross? (5.7) K/U
(a) RRYY
(b) RRYy
(c) RrYY
(d) RrYy
9. In a family with three children, what is the probability that the first child is a boy, the second child is a girl, and the third child is a boy? (5.7) K/U
(a) 12.5 %
(b) 25 %
(c) 50 %
(d) 75 %
Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true.
10. In genetics, the mating of two organisms is called an allele. (5.1) K/U
11. Recessive alleles are expressed only when both alleles are the same. (5.1) K/U
12. An individual's outward appearance for a particular characteristic is his or her phenotype. (5.1) K/U
13. Each parent passes along one allele for each gene. (5.1) K/U
14. A Punnett square is a diagram that can be used to predict the outcome of a cross between two organisms. (5.1) K/U
15. If the chance of event A is 25 % and the chance of event B is 10 %, then the chance of both event A and B occurring is 35 %. (5.1) K/U
16. AB blood type in humans is an example of incomplete dominance. (5.2) K/U
17. On a pedigree chart, an affected female is indicated by a shaded square. (5.3) K/U
18. In autosomal inheritance, males and females are affected equally. (5.3) K/U
19. A trait that occurs in all of the males of a family and none of the females is probably X-linked. (5.3) K/U
20. An individual who is heterozygous for the allele that causes cystic fibrosis is called a carrier. (5.5) K/U
21. Neurofibromatosis is a genetic disorder that is a recessive trait. (5.5) K/U
22. Height is an example of a human characteristic that shows discontinuous variation. (5.7) K/U
23. Skin colour is a human characteristic affected by additive alleles. (5.7) K/U
24. An individual with the genotype RrGG can produce gametes with three different allele combinations. (5.1, 5.7) K/U
To do an online self-quiz, GO TO NELSON SCIENCE
Print Page 220
CHAPTER 5 REVIEW
Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
Knowledge
For each question, select the best answer from the four alternatives.
1. In a cross, the P generation consists of two true-breeding pea plants: one with purple flowers and one with white flowers. How many different genotypes will be present in the F1 generation? (5.1) K/U
(a) 1
(b) 2
(c) 3
(d) 4
2. What term describes an individual who carries only one type of allele for a gene? (5.1) K/U
(a) heterozygous
(b) monohybrid
(c) homozygous
(d) dihybrid
3. What pattern of heredity is demonstrated when, in shorthorn cattle, a cross between a red bull and a white cow results in roan calves? (5.2) K/U
(a) complete dominance
(b) codominance
(c) incomplete dominance
(d) X-linked dominance
4. In humans, which blood type is the result of codominance? (5.2) K/U
(a) type A
(b) type B
(c) type AB
(d) type 0
5. A pedigree chart shows two unaffected parents who have two affected offspring and two unaffected offspring. What are the genotypes of the parents for the trait? (5.3) K/U
(a) heterozygous
(b) homozygous recessive
(c) homozygous dominant
(d) impossible to determine
6. On a pedigree chart, what symbol indicates an affected male? (5.3) K/U
(a) shaded square
(b) shaded circle
(c) unshaded square
(d) unshaded circle
7. How is the probability of two independent events both occurring calculated? (5.7) K/U
(a) Multiply the probabilities of the events.
(b) Add the probabilities of the events.
(c) Subtract the probabilities of the events.
(d) Divide the probabilities of the events.
8. What phenotype ratio is expected in a dihybrid cross? (5.7) K/U
(a) 3:1
(b) 1:2:1
(c) 9:3:3:1
(d) 3:1:9
Match each term on the left with the most appropriate description on the right
9. (a) galactosemia
(b) Tay-Sachs disease
(c) Huntington's disease
(d) Lesch-Nyhan syndrome
(e) hemophilia
(i) buildup of uric acid in the body
(ii) progressive degeneration of the nervous system
(iii) inability to digest galactose
(iv) inability to form blood clots
(v) nerve cells in the brain are affected by the accumulation of gangliosides (5.5) K/U
Indicate whether each statement is true or false. If you think the statement is false, rewrite it to make it true.
10. The set of alleles an individual has is called its genotype. (5.1) im
11. An allele that is always expressed whenever it is present is a recessive allele. (5.1) K/U
12. When an individual who is heterozygous for a trait has a blended phenotype, this is called codominance. (5.2) K/U
13. For blood type, humans have three different alleles. (5.2) K/U
14. In a pedigree chart, Roman numerals are used to specify generations. (5.3) K/U
15. A disorder that can be passed only from father to son is X-linked. (5.3) K/U
16. Carrier testing is used to identify individuals who carry disorder-causing dominant alleles. (5.5) K/U
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Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
17. If both parents are carriers of cystic fibrosis (CF) but do not have the disease themselves, the probability that they will have a child with CF is 1 in 4. (5.5) K/U
18. Dihybrid crosses can be used to demonstrate the law of independent assortment. (5.7) K/U
Write a short answer to each question.
19. List the seven characteristics of pea plants that Mendel investigated. (5.1) K/U
20. In a monohybrid cross, what ratio of phenotypes would you expect to find in the offspring? (5.1) K/U
21. Define the term "allele!' (5.1) K/U
22. During which stage of meiosis do homologous chromosomes separate? (5.1) K/U
23. List the possible genotypes of the offspring of a cross between an individual with the genotype Hh and another individual with the genotype Hh. (5.1) K/U
24. If a red-flowering snapdragon were crossed with a white-flowering snapdragon, what percentage of the offspring would you expect to be red-flowered? (5.2) K/U
25. Draw a pedigree chart that shows a family with an affected father and an unaffected mother whose children are, in the following order, an unaffected son, an affected daughter, and a second unaffected son. (5.3) K/U
26. Cystic fibrosis causes the body of affected individuals to produce thick, sticky mucus. Identify three specific ways that this affects the body. (5.5) K/U
27. In a family in which both parents are carriers of cystic fibrosis but do not have the disease themselves, what percentage of their offspring would you expect to be carriers of CF but not have the disease? (5.5) K/U
28. In a dihybrid cross, how many possible genotypes can result in the offspring? (5.7) K/U
Understanding
29. Explain why Mendel removed the male reproductive organs in some of the plants used in his investigations. (5.1) K/U
30. (a) Contrast the meaning of the terms "characteristic" and "trait:'
(b) Give one example of a human characteristic and one example of a human trait. (5.1) K/U
31. List two characteristics of the garden pea that made it an ideal plant for Mendel to use in his experiments. (5.1) K/U
32. Can an allele that is not expressed in an individual be passed on to that individual's offspring? Explain why or why not. (5.1) K/U T/I
33. An individual is heterozygous. Is her dominant allele more or less likely to be passed on to her offspring than her recessive allele? Explain. (5.1) CM K/U T/I
34. Restate in your own words the two conclusions that form the law of segregation. (5.1) K/U
35. (a) Describe the "blending" theory that was accepted by many scientists at the time Mendel performed his investigations.
(b) Explain how Mendel's work disproved this theory.
(c) Discuss how the results might have differed if Mendel had worked with snapdragons rather than pea plants. (5.1) K/U
36. Compare and contrast codominance and complete dominance. Identify one way they are similar and one way they are different. (5.2) K/U T/I
37. What scientific advances are responsible for test crosses being performed less often than they used to be? (5.1) K/U T/I
38. A given gene for a codominant trait has multiple alleles. Explain how these multiple alleles can increase the variation in a population. (5.2) K/U T/I
39. A farmer crosses a roan bull and a roan cow. (5.2) K/U T/I
(a) What is the expecte genotype ratio of the offspring?
(b) What is the expected phenotype ratio of the offspring?
(c) What is the probability of an offspring of this cross being red?
(d) What is the probability of an offspring of this cross being roan?
40. (a) Compare and contrast a Punnett square and a pedigree chart. Describe one way that they are similar and one way that they are different.
(b) Explain how a genetic counsellor could use each of these tools. (5.1, 5.3, 5.5) K/U T/I
41. The analysis of some pedigree charts provides proof that a trait is dominant. Draw an example of a pedigree chart that illustrates this point. (5.3) K/U C
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Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
42. Interpret the pedigree chart in Figure 1. (5.3) T/I A
Figure 1
Image: (I) A square(I-1) and a shaded circle(I-2): mating; (II) A circle(II-1), a shaded circle(II-2)not a sibling connected to a square(II-3), a square(II-4), a square(II-5), a square(II-6) connected to a circle(II-7)not a sibling; (III) Shaded circle(II-2) and square(II-3): mating, are connected by a vertical line to (III) A shaded square(III-1), a circle(III-2), a circle(III-3), and a shaded circle(III-4): siblings; Square(II-6) and circle(II-7): mating, are connected by a vertical line to circle(III-5): child.
(a) How many offspring of the individuals in generation I are shown in the pedigree chart?
(b) How many offspring of generation I are affected with the disorder?
(c) In generation III, how many affected individuals are shown?
(d) Redraw the pedigree to indicate that 11-4 and 11-5 are identical twins.
(e) Is the trait controlled by a dominant or a recessive allele? Explain your reasoning.
(f) Which individuals must be carriers?
(g) Could this trait be X-linked recessive? Explain your reasoning.
43. Individuals who carry out genetic research are usually motivated by scientific curiosity. Explain why Dr. Nancy Wexler had motivation beyond scientific curiosity to investigate Huntington's disease. (5.4) K/U T/I
44. (a) What is a "marker" for a genetic disorder?
(b) What is the significance of finding a marker for a genetic disorder, such as Huntington's disease?
(c) How have advances in DNA technology furthered research on Huntington's disease? (5.4) K/U
45. (a) Summarize the dietary restrictions recommended for an individual with phenylketonuria (PKU).
(b) What are the consequences for an individual with PKU if these restrictions are not followed? (5.5) K/U
46. (a) Describe how genetics can play a role in the development of breast cancer in an individual.
(b) Describe how the environment can play a role in the development of breast cancer in an individual. (5.5) K/U
47. (a) Compare and contrast continuous variation and discontinuous variation.
(b) Give one example of each type of variation. (5.7) K/U T/I
48. Describe how additive alleles play a role in the great variation of human skin colour. (5.7) K/U
Analysis and Application
49. A test cross was carried out to determine if a bull displaying a dominant trait was heterozygous or homozygous. The alleles for the trait are designated by the letters T and t. The offspring display both dominant and recessive phenotypes. Draw a Punnett square that shows the alleles produced by both parents and the genotypes of the offspring. (5.1) T/I A
50. Assess the importance of each of the following aspects of Mendel's experimental design. Write a sentence for each aspect of Mendel's work, explaining its significance. (5.1) T/I A
(a) the use of pea plants
(b) the number of pea plants tested
(c) recording and analyzing large amounts of data
(d) reporting results that differed from the results that were expected
51. In pea plants, inflated pod shape (I) is dominant over constricted pod shape (i). (5.1) T/I A
(a) List two genotypes that would result in a phenotype of inflated pods.
(b) Identify a genotype that would result in a phenotype of constricted pods.
(c) A cross between two pea plants results in 100 % of the offspring having constricted pods. What were the genotypes of the two parent pea plants?
(d) Explain how you can be sure of your response to part (c).
52. A child is born with a trait that is not present in either of the child's biological parents. (5.1) T/I C A
(a) Is the child's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know?
(b) Is the mother's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know?
(c) Is the father's genotype for the trait homozygous recessive, homozygous dominant, or heterozygous? How do you know?
(d) The alleles for this trait can be represented with the letters B and b. Draw a Punnett square that shows this cross. In the completed Punnett square, circle the genotype that represents the child described in the question.
(e) What is the probability of these parents having another child with the same trait as the child described in the question?
53. How might Mendel's conclusions have differed if he finished his experiment after observing the F1 generation instead of the F2 generation? (5.1) T/I A
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Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
54. In Andalusian chickens, the alleles for feather colour exhibit incomplete dominance. An individual with one allele for black feathers and one allele for white-splashed feathers displays a blue-feather phenotype (Figure 2). (5.2) T/I C A
(a) Would a chicken of this variety with black feathers be heterozygous or homozygous? How do you know?
(b) Would a chicken of this variety with blue feathers be heterozygous or homozygous? How do you know?
(c) If two chickens with blue feathers are crossed, what phenotype or phenotypes will the offspring have?
Figure 2
Image: A chicken with black and white feathers
55. If two roan cattle are crossed, they have a greater likelihood of producing a roan offspring than they do of producing a red offspring or a white offspring. Explain why this is true. (5.2) T/I A
56. A farmer wants to produce only roan cattle on his farm. Should he start with two roan cattle or with one red and one white? Explain your answer. (5.2) T/I A
57. If there was room to stock and carry only one type of blood to use for transfusions in an ambulance, what type of blood should be chosen? Explain your response. (5.2) T/I A
58. A child's biological father has blood type AB. The child's mother does not know her blood type. (5.2) T/I A
(a) Using this information, identify three blood types the child could have.
(b) Explain how each of these blood types could occur in the child.
(c) Identify a blood type that could not be present in the child. Explain your thinking.
59. Apply what you have learned about alleles and variation in a population to explain why finding an appropriate donor for a transplant is typically very difficult. (5.2) T/I A
60. A pedigree chart shows a cross between two unaffected individuals that produces an affected individual. (5.3) K/U
(a) Using only this information, is it possible to determine if the trait is dominant or recessive? Explain your thinking.
(b) Using only this information, is it possible to determine the genotype of the affected individual? Explain your thinking.
61. Some genetic disorders are classified as X-linked disorders. (5.3) T/I A
(a) Explain how X-linked disorders differ from autosomal disorders.
(b) Give one example of an X-linked disorder in humans.
(c) If an X-linked disorder is recessive, can a male be a carrier of this disorder? Why or why not?
62. (a) If carrier testing is available for a human genetic disorder, is the disorder caused by a dominant allele or a recessive allele? How do you know?
(b) Give an example of a disease for which carrier testing is available. (5.5) K/U T/I A
63. A couple is evaluating their chances of having a child born with cystic fibrosis (CF). Both the man and the woman know their family's medical history for the past two generations—there have been no children born with CF. Is it possible for this couple to have a child with CF? Explain why or why not. (5.5) T/I
64. Some adopted individuals have access to their medical histories, while others do not. Explain how the information in this chapter could be applied to argue for the importance of all adopted individuals having access to medical histories of their biological parents. (5.5) T/I C A
65. In genetics, the expected probability of a trait can be calculated. There is typically a difference between the predicted probability and the actual rate of occurrence of the trait in a population. Explain how the size of this difference changes as the size of the observed population increases. (5.7) T/I A
66. Does the law of independent assortment apply to genes located on the same chromosome? Why or why not? (5.7) T/I A
67. In foxes, two alleles, PP and PS, influence survival and hair colour. PPPP zygotes do not survive. PPPS individuals have normal health and platinum coat colour. PSPS individuals also have normal health and have a silver coat. What are the expected genotype and phenotype ratios of offspring from the cross of a platinum and a silver fox? K/U A
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Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
Evaluation
68. When a true-breeding purple pea plant and a true- breeding white pea plant are crossed, the trait of white flowers is not seen in the F1 generation. Some people say that the trait of white flowers "disappears" in the F1 generation. (5.1) T/I C A
(a) Evaluate the use of the word "disappears" to describe what occurs.
(b) Suggest a term that better reflects what happens to the trait of white flowers. Explain your thinking.
69. It is a common misconception that the traits most commonly seen in a population are dominant traits. However, this is not the case. For example, in humans, freckles are a dominant trait, but they are found in only a small portion of the population. Use this information and the information you have learned about allele frequency to develop an explanation that addresses this misconception. (5.1) T/I C A
70. Evaluate the term "father of genetics:' which has been used to describe Mendel. Explain why this is a fitting description, based on his work. (5.1) T/I C A
71. Would a Punnett square be a useful real-life tool to predict all of the traits of a human child? Write a paragraph that gives two specific reasons why or why not. (5.1) T/I C A
72. Your friend strongly resembles his father but looks very different from his mother. He states that he must have received two alleles for many of his traits from his father and none from his mother. Evaluate your friend's statement. Explain whether it is a good explanation for his resemblance to his father or not. (5.1) T/I C A
73. Imagine you are a geneticist. Which area of research would you be most interested in: developing better genetic screening procedures, developing and testing new treatments, or some other area of research? What factors influenced your choice? (5.5) T/I C A
74. Both genetics and the environment can play roles in the development of breast cancer. Do you think that all women should be screened for defective BRCA1 and BRCA2 genes so they can then use that information to determine how careful they should be regarding certain environmental factors? Explain your response. (5.5) T/I A
75. Your seven-year-old brother has a new classmate who has cystic fibrosis. Your brother states that he does not want to sit next to the new student because he is afraid of catching CF. Evaluate your brother's statement. Identify the misconception your brother has, and write a paragraph to explain to your brother why he should not be concerned about contracting cystic fibrosis from his classmate. (5.5) T/I C A
76. The Ontario Newborn Screening Program checks for certain disorders. Do you think it should be expanded to include disorders that will not appear until much later in life, such as Huntington's disease? Explain your response. (5.5) T/I C A
77. Should individuals have complete control over who accesses the results of any genetic testing they have undergone? Explain your response. (5.6) T/I A
78. A family you know has three boys and no girls. They are expecting their fourth baby. You overhear someone saying that the family is likely to have a girl this time, because they have had three boys already. Is this statement valid? Write a paragraph to explain why. (5.7) T/I C A
Reflect on Your Learning
79. Mendel's work did not yield the results that most scientists of his time would have expected. Even so, he carefully recorded and reported his data. Does learning this information change your feelings about the importance of getting the "expected" results when carrying out an experiment? Why or why not? T/I A
80. After reading the information in this chapter, do you think you will actively seek out carrier testing for cystic fibrosis if you decide to have biological children? Why or why not? T/I A
81. If you could perform medical research in hopes of eradicating one genetic disorder, on what disorder would you focus your research? Explain your choice. T/I A
82. What section of this chapter did you find most interesting? What section contains information that will be most applicable to your life? Explain each of your responses. T/I A
83. If your family history included individuals with Huntington's disease, would you opt for or against genetic testing to determine if you carry the gene? Explain your response. T/I A
Research GO TO NELSON SCIENCE
84. Gregor Mendel's work occurred primarily in the years 1856 to 1866, although the importance of his work was not recognized for many years. Research and write a short report on one other scientific advance, world event, contribution to music or the arts, or other significant event that occurred in this same time period. Share your report with your classmates. T/I C A
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Key
K/U: Knowledge and Understanding
T/I: Thinking and Investigation
C: Communication
A: Application
85. Research to learn more about Reginald Punnett, the individual for whom Punnett squares were named. Prepare a short oral report to share what you have learned with your classmates. T/I C A
86. The treatment for the genetic disorder phenylketonuria includes many dietary restrictions. Research these dietary restrictions. Then develop a menu for a day's meals that follow these restrictions. Share your menu with a small group of students. (5.7) T/I C A
87. The Human Genome Project (HGP) was a large-scale project that resulted in the sequencing of the human genome. Research the disease-causing genes that have been located as a result of the work done during the HGP. Prepare a short report that summarizes information about the HGP, and explain how it is related to advances in the treatment or diagnosis of genetic diseases. T/I C A
88. Sickle-cell anemia is a trait caused by a recessive allele. Carriers, who have one sickle-cell allele, have an increased resistance to malaria. Research sickle-cell anemia for information about its symptoms and treatment, the regions where the sickle-cell trait is most common, and how that relates to malaria resistance. Present your findings as a short newspaper-style article. T/I C A
89. A new trend in genetic testing is direct-to-consumer genetic testing. This is genetic testing that does not involve a healthcare provider. An individual purchases a test, provides a sample, and receives the results without a visit to the doctor. Learn more about direct-to-consumer genetic testing and its advantages and disadvantages. Share what you learn in a class-discussion format. Be prepared to state your opinion about whether direct-to-consumer genetic testing is helpful or harmful. T/I C A
90. Duchenne muscular dystrophy is a genetic disorder that affects males. Research the symptoms of this disorder and its mode of inheritance. Prepare four note cards, each with a different specific fact about Duchenne muscular dystrophy. Then discuss this disorder with three other students in a small-group format. Use the information on your note cards in the discussion. After you have shared a fact, pass around the card containing the fact so others can read the information on the card. T/I C A
91. Research to find out more about the Ontario Newborn Screening Program. Locate the list of all conditions that this program screens for. Then select a condition that was not described in this chapter for which screening is performed. Use the resources available through the Newborn Screening website and other reliable websites to find out more about this condition. Make a pamphlet to share what you have learned with others. Your pamphlet must present information in an organized format and include illustrations or diagrams. T/I C A
92. Polycystic kidney disease is a human genetic disorder that affects millions of people worldwide. This disorder has two forms: autosomal dominant and autosomal recessive. Research the symptoms, testing, and treatment for both forms of this disorder. Prepare a short oral report to share what you have learned. T/I C A
93. Early on in the embryonic development of female mammals, one of the X chromosomes in every cell becomes almost entirely inactivated and forms a Barr body. Do research to learn more about the formation of the Barr body and what it means for female Calico cats (Figure 3).
(a) Why are there no male Calico cats?
(b) Why are the colour patterns on the females made up of random patches?
(c) Are all aspects of their colour influenced by the same alleles?
Figure 3
Image: A black, white and brown Calico cat.