Answer Key Chapter Test A Multiple Choice 1. 2. 3. 4. 5. 6. 7. b c d c c c a 8. 9. 10. 11. 12. 13. 14. 15. a d c c a d c b more males than females with the phenotype. 25. Students should draw Punnett square with W/w at the top and w/w at the left side; resulting offspring Ww, Ww, ww, ww Copyright by McDougal Littell, a division of Houghton Mifflin Company Short Answer 16. C2C2 17. pink 18. Parents are C1C1 and C2C2; all offspring are C1C2. 19. 1 = C1C1, 2 = C1C2, 3 = C1C2, 4 = C2C2; incomplete dominance 20. Codominance. The phenotypes of both parents are expressed fully and separately in the offspring. 21. a pedigree chart 22. individuals with a given phenotype 23. The phenotype is caused by a dominant allele because the father has genotype ww and does not have the phenotype. Additionally, the mother has genotype Ww and has the phenotype. 24. There are more females than males with the phenotype. When a gene is sex-linked, there will be Answer Key 1 CHAPTER 7 EXTENDING MENDELIAN GENETICS Chapter Test A Multiple Choice Choose the letter of the best answer. (15 credits) 1. A person who has a disorder caused by 5. For an XX female to express a recessive a recessive allele is sex-linked trait, she must have a. considered a carrier of the disorder. a. a Y chromosome. b. homozygous for the recessive allele. b. an inactivated allele. c. two recessive alleles. d. two dominant alleles. disorder. 6. Human height occurs in a continuous 2. Gene expression is influenced by many factors. Which of the following is a factor in gene expression? a. karyotype c. environment b. pedigree d. phenotype 3. The Punnett square in Figure 7.1 shows a cross between two parents who have the genotype Ss for a genetic disorder caused by a recessive allele. Which of the following will have the genetic disorder? range because it is affected by the interaction of several genes, making it a a. autosomal trait. b. sex-linked trait. c. polygenic trait. d. codominant trait. 7. Suppose a mouse is homozygous for CHAPTER 7 Extending Mendelian Genetics c. unable to pass the allele to offspring. d. certain to have offspring with the alleles that produce black fur and homozygous for alleles of an epistatic gene that prevents fur coloration. What color fur will the mouse have? Copyright © McDougal Littell/Houghton Mifflin Company. a. all white b. mostly black c. entirely gray d. black and white FIG. 7.1 a. Ss parent c. SS offspring b. Ss offspring d. ss offspring 4. Two parents have the genotype Gg for a genetic disorder caused by a dominant allele. What is the chance that any of their children will inherit the disorder? a. 25% c. 75% b. 50% d. 100% Assessment Book McDougal Littell Biology Chapter Test A 133 CHAPTER TEST A, CONTINUED 8. The gene linkage map shown in Figure 7.2 shows the order of genes A, B, and C. Which of the following statements about the genes is true? 8.5 C A FIG. 7.2 CHAPTER 7 Extending Mendelian Genetics a. The distance between A and B is 14.5 map units. b. A and B cross over 2.5% of the time. c. A and C are linked 8.5% of the time. d. B and C are most likely to be inherited together. 9. Thomas Morgan’s research with fruit flies determined that a. does not have the disorder but can pass it on b. will develop the disorder only late in life c. cannot pass the disorder to sons, just daughters d. the allele is not passed on due to Y chromosome inactivation 13. Some members of a family have a recessive sex-linked disorder. Which of the following statements about the family would be true? a. All males would have the disorder. b. All females would be carriers. a. alleles always assort independently. c. Only males would have the disorder. b. chromosomes are inherited as a d. Only females would be carriers. group. c. genes never assort independently. d. traits sometimes are inherited as a group. 10. Two genes cross over 6% of the time. This percentage means that the genes are a. inactivated in 6 out of 100 offspring. b. incompletely dominant in 6 out of 100 offspring. c. not inherited together in 6 out of 100 offspring. d. on sex chromosomes in 6 out of 100 offspring. 11. A female is born with attached earlobes, which is a recessive phenotype. Which of the following genotypes could her parents have? 134 genetic disorder. Which of the following phrases about this person is true? a. RR and RR c. Rr and rr b. Rr and RR d. RR and rr Chapter Test A 14. What is the main reason that sex-linked disorders are most often observed in males? a. The X chromosome only has genes for genetic disorders. b. The Y chromosome cannot have genes that cause genetic disorders. c. The Y chromosome cannot mask alleles on the X chromosome. d. The X chromosome has genes only for sex determination. 15. Which of the following tools is used to match up chromosome pairs using chemical stains? a. pedigree chart c. meiosis map b. karyotype d. linkage map Assessment Book McDougal Littell Biology Copyright © McDougal Littell/Houghton Mifflin Company. B 6 12. Suppose a person is a carrier for a CHAPTER TEST A, CONTINUED Short Answer Use the diagram below to answer items 16–20. (5 credits) Crosses Between Parental Generation Pea Plants X Red White First Generation X Pink ? Second Generation Red C1C1 Pink C1C2 Pink C1C2 CHAPTER 7 Extending Mendelian Genetics FIG. 7.3 White C2C2 16. Write the genotypes of the pea plants in the parental generation shown in Figure 7.3. 17. What is the phenotype of the unlabeled pea plant in the first generation? 18. Use the genotypes of the parents to make a Punnett square for the first generation of Copyright © McDougal Littell/Houghton Mifflin Company. offspring. 19. Which type of interaction is shown by the alleles for flower color? 20. Suppose the first generation pea plants had flowers that were partly red and partly white instead of all pink. What type of relationship between alleles would this be? Write one statement to support your answer. Use the word phenotype in your answer. Assessment Book McDougal Littell Biology Chapter Test A 135 CHAPTER TEST A, CONTINUED Use the diagram below to answer items 21–25. (5 credits) = male without phenotype Ww 1 2 ww 3 = female without phenotype 4 5 CHAPTER 7 Extending Mendelian Genetics FIG. 7.4 21. What type of chart is shown in Figure 7.4? 22. What do the shaded shapes represent? 23. The phenotype is caused by a dominant allele. Write two statements to support this fact. 25. Make a Punnett square using the parental genotypes. Find all the possible genotypes for the offspring in the F1 generation. 136 Chapter Test A Assessment Book McDougal Littell Biology Copyright © McDougal Littell/Houghton Mifflin Company. 24. The phenotype is caused by an autosomal gene. Explain why.