chapter 13 - observing patterns in inherited traits · web viewin the late 1920s, a mutation...

Chapter 13 - Observing Patterns in Inherited Traits

Multiple Choice

1. The CFTR protein product is responsible for a. pumping chloride ions out of the cell. b. pumping water out of the cell. c. pumping chloride ions into the cell. d. fighting off bacterial infections. e. regulating gene expression.ANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.1 Menacing MucusLEARNING OBJECTIVES:

UDOL.STES.16.13.1 - Examine the negative consequences of the genetic disorder known as cystic fibrosis.

2. Where is the CFTR gene expressed at the highest levels? a. lungs b. reproductive system c. intestines d. brain e. skinANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.1 Menacing MucusLEARNING OBJECTIVES:


3. Which of the following is TRUE of cystic fibrosis? a. It results in reduced mucus production. b. It leads to increased bacterial lung infections. c. It affects the amino acid alanine. d. It causes excess water to leave the cells. e. It most often affects the liver.ANSWER: bDIFFICULTY: Bloom's: RememberREFERENCES: 13.1 Menacing MucusLEARNING OBJECTIVES:


4. Which statement most completely describes why the pea plant was an excellent choice for Mendel's experiments? a. True-breeding varieties were available. b. The plant can self-fertilize. c. The plant can be cross-fertilized. d. True-breeding varieties were available, and it can be cross-fertilized. e. True-breeding varieties were available, the plant can self-fertilize, and it can be cross-fertilized.ANSWER: e

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DIFFICULTY: Bloom's: EvaluateREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

5. A gene locus is a. a recessive gene. b. an unmatched allele. c. a sex chromosome. d. the location of a gene on a chromosome. e. a dominant gene.ANSWER: dDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

6. Various forms that a single gene can take at a given locus are called a. kinetochores. b. alleles. c. autosomes. d. loci. e. chromatids.ANSWER: bDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

7. In humans, the locus of the CFTR gene is on chromosome ____. a. 7 b. 15 c. 19 d. 20 e. 29ANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

8. The most accurate description of an organism with genotype AaBb is a. homozygous dominant. b. heterozygous. c. heterozygous dominant. d. homozygous recessive. e. heterozygous recessive.ANSWER: b



DIFFICULTY: Bloom's: ApplyREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

9. According to Mendel, if a male that is homozygous for the dominant form (PP) of a trait is crossed with a female that is homozygous for the recessive (pp) form of a trait, all offspring will show the ____ form of the trait. a. sex-linked b. dominant c. recessive d. codominant e. lethalANSWER: bDIFFICULTY: Bloom's: RememberREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

Figure 13.7

10. Using the accompanying illustration and the assumption that half of a plant's sperm and eggs are p and half are P, one can predict that the chance of sperm p meeting egg P at fertilization is ____. a. 50% b. 75% c. 25% d. ½ X ¼ e. 100-%ANSWER: cDIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationPREFACE NAME: Figure 13.7LEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.



11. For Mendel's explanation of inheritance to be correct, ____. a. the genes for the traits he studied must be located on the same chromosome b. the combination of gametes at fertilization must be due to chance c. genes cannot be transmitted independently of each other d. only diploid organisms demonstrate inheritance patterns e. only triploid organisms demonstrate inheritance patternsANSWER: bDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

12. An individual with a genetic makeup of aa BB is called a. true-breeding. b. recessive. c. hybrid. d. dihybrid. e. heterozygous.ANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:

UDOL.STES.16.13.4 - Demonstrate Mendel’s law of independent assortment using a dihybrid cross.

Figure 13.8



13. Which offspring in the illustration above are homozygous recessive for both traits? a. PPTT b. ppTT c. PpTt d. pptt e. PPttANSWER: dDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentPREFACE NAME: Figure 13.8LEARNING OBJECTIVES:


14. Mendel's dihybrid crosses, but not his monohybrid crosses, show that a. some genes are linked together. b. the two alleles controlling a trait are divided equally among the gametes. c. alleles for different traits are inherited independently. d. one of the pair of alleles is dominant to the other. e. the crossing of two different homozygous forms will not produce any offspring in the first generation that

will look like either of the parents.ANSWER: cDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


15. In ____, a pair of nonidentical alleles affecting the phenotypes of a given trait are both expressed at the same time in heterozygotes. a. pleiotropy b. polygenic inheritance c. complete dominance d. codominance e. a multiple allele systemANSWER: dDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

16. The ABO blood types are an example of ____. a. pleiotropy and polygenic inheritance b. multiple alleles and continuous variation c. incomplete dominance d. codominance and epistasis e. multiple alleles and codominanceANSWER: e



DIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

17. The accompanying illustration shows the F2 phenotypes from a monohybrid cross in snapdragons. What type of inheritance produces such an outcome? a. complete dominance b. incomplete dominance c. multiple alleles d. continuous variation e. epistasisANSWER: bDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.5 Beyond Simple DominancePREFACE NAME: FigureLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

18. Genes at one locus that affect the expression of genes at a different locus are said to be a. epistatic. b. linked. c. codominant. d. continuous. e. alleles.ANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.



Figure 13.12

19. The F2 phenotypic ratio of 9:3:4, as shown above, is a result of a cross involving a. two genes expressing complete dominance. b. a gene expressing dominance and another gene expressing codominance. c. two genes expressing codominance. d. epistasis, in which one gene modifies the expression of the other gene. e. multiple alleles.ANSWER: dDIFFICULTY: Bloom's: Understand

Bloom's: EvaluateREFERENCES: 13.5 Beyond Simple DominancePREFACE NAME: Figure 13.12LEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

20. A gene that produces multiple effects is called a(n) a. multiple allele. b. autosome. c. epistatic gene. d. pleiotropic gene. e. incompletely dominant gene.ANSWER: dDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

21. A species is found to exist in one of three colors. Assuming an epistatic interaction, how many genes would be involved? a. zero b. one



c. two d. three e. sixANSWER: cDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

22. What term is used for multiple effects from a single gene? a. expressivity b. continuous variation c. codominance d. pleiotropy e. multiple allelesANSWER: dDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

23. Pleiotropic genes ____. a. act on secondary sexual characteristics b. influence more than one aspect of phenotype c. are additive d. produce lethal effects when homozygous e. can only affect one trait or characteristic at a time ANSWER: bDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

24. Which of the following is true about Marfan syndrome? a. The cause is an autosomal recessive mutation. b. The affected gene produces a defective form of the protein actin. c. Connective tissues are weakened. d. One in 5,000 men are affected. e. Those affected are often very short and have mental impairments. ANSWER: cDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

25. Which of the following is associated with Marfan syndrome? a. lanky, loose jointed skeleton b. reduced eye sight



c. calcium deposits in the liver d. excessive production of red blood cells e. skin becomes elasticANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

26. The role of environmental factors on gene expression is illustrated by ____. a. the varying plant height of genetically identical yarrow plants when grown at different elevations b. the flower color of hydrangeas c. the coloration in snapdragon plants d. male-pattern baldness e. genetic variety in eye colorANSWER: aDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:

UDOL.STES.16.13.6 - Examine the influence of the environment on the phenotype of an organism using examples.

27. In the classic argument of ‘nature vs. nurture’, nature would most correspond with a. genes. b. environment. c. divine intervention. d. environment and genes. e. genes, environment, and genes.ANSWER: aDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


28. Four of the following will stimulate the production of males in water fleas. Which one is the exception? a. spring b. warm water c. salty water d. high competition for resources e. crowdingANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


29. Diet, stress, and exercise can all impactCopyright Cengage Learning. Powered by Cognero.


a. the development of all autosomal disorders. b. the development of autosomal recessive disorders. c. the development of autosomal dominant disorders. d. multiple allele systems. e. DNA methylation patterns.ANSWER: eDIFFICULTY: Bloom's: RememberREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


30. Which most completely describes the circumstances under which yarrow will alter its phenotype? a. temperature, soil conditions and water conditions b. soil conditions only c. being produced by sexual versus asexual reproduction d. water conditions only e. asexual reproduction, soil conditions, and water conditionsANSWER: aDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


31. In which of the following does the environment play a causal role? a. Marfan syndrome b. cystic fibrosis c. dog coat color d. sickle-cell anemia e. depression and schizophreniaANSWER: eDIFFICULTY: Bloom's: RememberREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


32. The ability of rats to cope with stress as adults can be affected by ____. a. a nurturing mother b. the number of siblings they have c. the temperature they are raised in d. the altitude they are born at e. their sex ANSWER: aDIFFICULTY: Bloom's: RememberREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIV UDOL.STES.16.13.6 - Examine the influence of the environment on the phenotype of an Copyright Cengage Learning. Powered by Cognero.


ES: organism using examples.

33. A bell-shaped curve of phenotypic variation is indicative of a. incomplete dominance. b. continuous variation. c. multiple alleles. d. epistasis. e. environmental variables on phenotypes.ANSWER: bDIFFICULTY: Bloom's: RememberREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:

UDOL.STES.16.13.7 - Examine the characteristics of continuous variation. DIF: Bloom's: Remember

Figure 13.17

34. A graph of phenotypic variation similar to the accompanying illustration strongly suggests a. incomplete dominance. b. codominance. c. epistasis. d. polygenic inheritance. e. environmental effects on phenotype.ANSWER: dDIFFICULTY: Bloom's: Understand

Bloom's: EvaluateCopyright Cengage Learning. Powered by Cognero.


REFERENCES: 13.7 Complex Variation in TraitsPREFACE NAME: Figure 13.17LEARNING OBJECTIVES:


35. Which statement is TRUE about Marfan syndrome? a. The elasticity of the aorta is affected. b. The condition affects the shape and mobility of fingers. c. Some affected individuals are of normal height. d. One in 500 people are affected. e. Marfan syndrome is easily diagnosed.ANSWER: aDIFFICULTY: Bloom's: Understand

Bloom's: EvaluateREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:


36. Height, weight, and eye color are examples of phenotypes that illustrate a. codominance. b. continuous variation. c. pleiotropy. d. incomplete dominance. e. multiple allele systems.ANSWER: bDIFFICULTY: Bloom's: Understand

Bloom's: EvaluateREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:


37. Environmental effects can result in a. altered metabolic pathways. b. a gene mutating in different ways in different individuals. c. altered genotypes. d. a post-developmental environmental effect. e. altered phenotypes.ANSWER: eDIFFICULTY: Bloom's: EvaluateREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:


38. Which eye color has dense melanin deposits in the iris? a. blue b. grayCopyright Cengage Learning. Powered by Cognero.


c. brown d. green e. brown and blueANSWER: cDIFFICULTY: Bloom's: UnderstandREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:


Matching

Answer the following questions using the group of answers below.a. 4b. 6c. 8d. 12e. 24DIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


39. In a dihybrid cross between a parent that is a double heterozygote (Aa Bb) and a parent that is homozygous dominant for one gene and heterozygous for the other (AA Bb), how many unique genotypes potentially will be present in their offspring?ANSWER: b

40. In a dihybrid cross between a parent that is a double heterozygote (Aa Bb) and a parent that is homozygous recessive for one gene and heterozygous for the other (aa Bb), how many unique phenotypes potentially will be present in their offspring?ANSWER: a

41. In a dihybrid cross between a parent that is a double heterozygote (Aa Bb) and a parent that is a double homozygous recessive (aa bb), how many unique phenotypes potentially will be present in their offspring?ANSWER: a

42. Plant species X is diploid (2n = 24) and has a quantitative trait, the expression of which is controlled by gene loci on each of its chromosomes. What is the maximum number of alleles for this trait that any one individual of species X could have?ANSWER: e

43. Animal species X is tetraploid (4n = 12). Following gene duplication and translocation, a given gene is found on each chromosome. How many alleles for this gene can be present in an individual of this species?ANSWER: d

Objective Short Answer

44. In a certain plant, when individuals with blue flowers are crossed with individuals with blue flowers, only blue flowers



are produced. Plants with red flowers crossed with plants with red flowers sometimes produce only red flowers, although other times they produce either red or blue flowers. When plants with red flowers are crossed with plants with blue flowers, sometimes only red flowers are produced; other times either red or blue flowers are produced. Which gene is dominant?ANSWER: RedDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:

UDOL.STES.16.13.5 - Outline the different ways in which an allele can influence an inherited trait using Punnett squares.

45. Which is easier to establish in a pure-breeding population, a dominant or a recessive gene?ANSWER: RecessiveDIFFICULTY: Bloom's: Understand

Bloom's: AnalysisREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

46. Tall (D) is dominant to dwarf (d). If a true-breeding tall plant is crossed with a true-breeding dwarf plant, give the genotypic and phenotypic ratios of the F2 generation.ANSWER: 1 DD, 2 Dd, 1 dd; 3 tall, 1 dwarfDIFFICULTY: Bloom's: ApplyREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

47. In humans, normal skin pigmentation is influenced by a dominant gene (C), which allows pigmentation to develop. All individuals who are homozygous for the recessive allele (c) are unable to produce an enzyme needed for melanin formation and are therefore referred to as albino. Two normal parents produce an albino child. What are the chances that the next child will be an albino?ANSWER: 1/4 chanceDIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

48. The allele for albinism (c) is recessive to the allele for normal pigmentation (C). A normally pigmented woman whose father is an albino marries an albino man whose parents are normal. They have three children, two normal and one albino. Give the genotypes for each person listed.ANSWER: Normal pigmented woman, Cc; albino father, cc; albino man, cc; normal parents, Cc + Cc; three

children, two normal Cc, 1 albino ccDIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES:

UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

49. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with purple flowers crossed with a dwarf plant with white flowers produces 1/2 tall with purple flowers and 1/2 tall with white flowers. What is the genotype of the parents?ANSWER: DD Pp x dd ppCopyright Cengage Learning. Powered by Cognero.


DIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


50. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with white flowers crossed with a dwarf plant with purple flowers produces all tall offspring with purple flowers. What is the genotype of the parents?ANSWER: DD pp x dd PPDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


51. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with purple flowers crossed with a dwarf plant with white flowers produces 1/4 tall purple, 1/4 tall white, 1/4 dwarf purple, and 1/4 dwarf white. What is the genotype of the parents?ANSWER: Dd Pp x dd ppDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


52. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with white flowers crossed with a dwarf plant with purple flowers produces 1/4 tall purple, 1/4 tall white, 1/4 dwarf purple, and 1/4 dwarf white. What is the genotype of the parents?ANSWER: Dd pp x dd PpDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


53. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with purple flowers crossed with a tall plant with white flowers produces 3/8 tall purple, 1/8 tall white, 3/8 dwarf purple, and 1/8 dwarf white. What is the genotype of the parents?ANSWER: Dd Pp x Dd ppDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


54. In garden peas, one pair of alleles controls the height of the plant, and a second pair of alleles controls flower color. The allele for tall (D) is dominant to the allele for dwarf (d), and the allele for purple (P) is dominant to the allele for white (p). A tall plant with purple flowers crossed with a tall plant with purple flowers produces 3/4 tall purple and 1/4 tall white. What is the genotype of the parents?Copyright Cengage Learning. Powered by Cognero.


ANSWER: D_ Pp x DD PpDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


55. In horses, black coat color is influenced by the dominant allele (B), and chestnut coat color is influenced by the recessive allele (b). Trotting gait is due to a dominant gene (T), pacing gait to the recessive allele (t). If a homozygous black trotter is crossed to a chestnut pacer,(a) What will be the phenotypes of the F1 and F2 generations?(b) Which phenotype will be the most common in the F2 generation?(c) Which genotype will be the most common in the F2 generation?(d) Which of the potential offspring will be certain to breed true?ANSWER: (a) F1: black trotters; F2: 9 black trotters, 3 black pacers, 3 chestnut trotters, 1 chestnut

pacer(b) Black trotter(c) Bb Tt(d) bb tt, chestnut pacers



56. In horses, black coat color is influenced by the dominant allele (B), and chestnut coat color by the recessive allele (b). Trotting gait is due to a dominant gene (T), pacing gait to the recessive allele (t). Give the genotype and phenotype of the horse you would use in a testcross to determine the genotype of a black trotter.ANSWER: bb tt, chestnut pacerDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


57. Crosses between a yellow rat with a yellow rat always produce yellow offspring. Crosses between a white rat with a white rat always produce white offspring. The alleles affect the same aspect of coat color. The cross of a white rat with a yellow rat produces a cream rat. If you cross two cream rats, what will be the ratios of phenotypes of the offspring?ANSWER: 1 yellow, 2 cream, 2 whiteDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


58. Assume that red plants crossed with white plants give rise to pink plants. Explain how to eliminate red plants if you start with two pinks.ANSWER: Cross two pink plants until you get white offspring. Cross two white plants, then all subsequent

plants will be white.DIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple Dominance



LEARNING OBJECTIVES:


59. In radishes, long or round are homozygous forms of an incompletely dominant gene, and oval is the phenotype of the heterozygote. If a long radish is crossed with a round radish, give the genotypic and phenotypic ratios of the F2 generation.ANSWER: 1 LL, 2 Ll, 1 ll; 1 long, 2 oval, 1 roundDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


60. A breeder of cattle has a herd of white cows and a roan bull. Hair color in this breed is controlled by an incompletely dominant gene. The two homozygous forms are either red or white, and the heterozygous is roan.(a) What colors of calves are expected and in what proportions?(b) Outline a procedure to develop an all-red herd.ANSWER: (a) 1/2 white, 1/2 roan

(b) Roan with white -- roan, roan x roan -- red, roan x red -- red, red x red -- redDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


61. In radishes, two incompletely dominant genes control color and shape. Red (R) is dominant over white (r), and heterozygotes are purple. Long (L) is dominant over round (l), and heterozygotes are oval. If a true-breeding red, long radish is crossed with a true-breeding white round radish, give the F2 genotypic and phenotypic ratios.ANSWER: 1 LL RR long red, 2 LL Rr long purple, 2 Ll RR oval red, 4 Ll Rr oval purple, 1 ll RR round red, 2 ll Rr

round purple, 1 LL rr long white, 2 Ll rr oval white, 1 ll rr round whiteDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


62. In a certain breed of chicken, an incomplete dominant gene controls color. The homozygous black (BB), when crossed with the homozygous splashed-white (bb), produces an intermediate gray color pattern referred to as blue. A second gene controls the shape of the comb. The dominant allele (R) produces rose, whereas the recessive allele (r) produces single. Give the F1 and F2 genotypic and phenotypic ratios of a cross between a true-breeding black with a single comb and a true-breeding splashed-white with a rose comb.ANSWER: F1: Bb Rr blue rose; F2: 3 BB R__ black rose, 6 Bb R__ blue rose, 3 bb R__ splashed-white rose, 1 BB

rr black single, 2 Bb rr blue single, 1 bb rr splashed-white singleDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


63. There are three alleles controlling the ABO blood types. IA and IB are codominant genes so that the combination IAIB produces the AB blood type. The third allele, i, is recessive to the other two alleles. Indicate which of these parents could produce the given child:Copyright Cengage Learning. Powered by Cognero.


Parents Child Yes or No(a) A ´ AB B(b) A ´ O A(c) A ´ B O(d) A ´ AB O(e) A ´ AB B(f) B ´ B O(g) AB ´ AB A

ANSWER: (a) Yes(b) Yes(c) Yes(d) No(e) Yes(f) Yes(g) Yes

DIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


64. In horses, there are four alleles at the A locus. Arranged in dominance sequence they are:

A (wild), ab (bay), ac (brown), ad (black)

If you bred several bay mares whose sires were brown to a brown stallion whose sire was black, what are the genotypes of the parents; what type of offspring would be produced; and in what proportion?ANSWER: abac x acad; 1/2 bay, 1/2 brownDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


65. In rabbits, there are four alleles at the c locus. Arranged in dominance sequence they are:

C (agouti), cch (chinchilla), ch (Himalayan), and c (albino)

(a) Is it possible to cross two agouti rabbits and produce both chinchilla and Himalayan offspring?(b) Is it possible to cross two chinchillas and produce 1/2 chinchilla and 1/2 Himalayan?ANSWER: (a) no

(b) not likely but possible--would expect a 3:1 ratio of chinchilla to HimalayanDIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


66. A cross of two Kerry horses always produces Kerry offspring. A cross of a Kerry with a Dexter produces 1/2 Kerry and 1/2 Dexter offspring. Crosses of two Dexters produce two Dexters for every Kerry. Explain.ANSWER: Kerry is homozygous (DD), Dexter is heterozygous (Dd), dd is lethal.



DIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


67. In the late 1920s, a mutation occurred in many silver fox farms around the world. The fox farms that sold expensive furs were proud of the quality of their furs, and each advertised that it had the best, purest breed of all the fox farms. The new mutations produced a "platinum" coat pattern that was commercially desirable, so the farms crossed them to get more. The results of their breeding experiments were as follows: (1) silver ´ silver >>> all silver offspring; (2) silver ´ platinum >>> equal numbers of silver and platinum; (3) platinum ´ platinum >>> two platinum for each silver offspring. Explain.ANSWER: PP (silver), Pp (platinum), pp (lethal)DIFFICULTY: Bloom's: ApplyREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:


68. In poultry, the genes for rose comb (R) and pea comb (P) produce walnut whenever they occur together (R__ P__); single-combed individuals have the homozygous condition for both genes (rr pp).(a) Give the F1 and F2 phenotypic results of a cross of a true-breeding rose comb (RR pp) with a true-breeding pea

comb (rr PP).(b) Give the phenotypic results of a cross of Rr Pp x rr Pp.(c) Give the phenotypic results of a cross of RR Pp x rr Pp.(d) Give the phenotypic results of a cross of Rr pp x rr Pp.(e) Give the phenotypic results of a cross of Rr Pp x rr pp.ANSWER: (a) F1: Rr Pp walnut; F2: 9 R__P__ walnut, 3 R__pp rose, 3 rr P__ pea, 1 rr pp single

(b) 3/8 walnut, 3/8 pea, 1/8 rose, 1/8 single(c) 3/4 walnut, 1/4 rose(d) 1/4 walnut, 1/4 rose, 1/4 pea, 1/4 single(e) 1/4 walnut, 1/4 rose, 1/4 pea, 1/4 single



69. Congenital deafness in humans is due to the homozygous condition of either of the recessive alleles d or e, or both. Both dominant D and E are necessary for normal hearing. Gene D/d affects the middle ear, while gene E/e affects the inner ear. It does not matter how good the normal inner ear (as indicated by E__) is; if there is something wrong in the middle ear, the individual is unable to hear. The same applies for the other gene. Give the phenotypic results of the following crosses:(a) Dd EE x Dd EE(b) Dd Ee x Dd Ee(c) dd EE x DD ee(d) Dd EE x Dd ee(e) Dd EE x DD EeANSWER: (a) 3/4 normal, 1/4 deaf

(b) 9/16 normal, 7/16 deaf(c) all normal(d) 3/4 normal, 1/4 deaf(e) all normal





70. White fruit color in summer squash is influenced by a dominant allele W, whereas colored fruit must be ww. In the presence of ww, a dominant gene G results in yellow fruit, and homozygous gg results in green fruit. Give the F2 phenotypic ratios resulting from a cross of a true-breeding plant with white fruit (genotype WW GG) with a plant with green fruit.ANSWER: 12/16 W__ __ __ white, 3/16 ww G __ yellow, 1/16 ww gg greenDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


71. In sweet peas, dominant alleles C and P are necessary for colored flowers. In the absence of either (__ pp or cc __) or both (cc pp), the flowers are white. What will be the color of the offspring of the crosses listed below and in what proportions?(a) Cc Pp x cc pp(b) Cc Pp x Cc Pp(c) Cc PP x Cc pp(d) Cc pp x cc Pp

ANSWER: (a) 1/4 color, 3/4 white(b) 9/16 color, 7/16 white(c) 3/4 color, 1/4 white(d) 1/4 color, 3/4 white



72. In sweet peas, dominant alleles C and P are necessary for colored flowers. In the absence of either (__ pp or cc __) or both (cc pp), the flowers are white. Give the probable genotype of a plant with colored flowers and a plant with white flowers that produced 38 plants with colored flowers and 42 plants with white flowers.ANSWER: Cc Pp x CC ppDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


73. In a certain breed of chicken, two genes control color. A dominant allele (I) inhibits the expression of any color gene (C). The recessive allele (c) results in albinism when homozygous (cc). Give the F2 phenotypic ratio of a cross between a colored chicken (ii CC) with a white chicken (II cc).ANSWER: 9 I__C__ + 3 I__ cc + 1 ii cc = 13 white + 3 ii C__ = 3 colorDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES UDOL.STES.16.13.4 - Demonstrate Mendel’s law of independent assortment using a dihybrid



: cross.

74. In mice the allele for colored fur (C) is dominant to the allele for albinism (c). The allele for normal behavior (W) is dominant to that for waltzing movement (w). Give the probable genotypes of the parents if they produced the offspring listed after the following crosses:(a) colored normal ´ white waltzer produced 10 colored normal, 8 colored waltzers, 2 white waltzers, 11 white normal(b) colored normal ´ white normal produced 35 colored normal, 13 colored waltzers(c) colored normal ´ colored normal produced 37 colored normal, 14 colored waltzers, 9 white normal, and 5 white

waltzersANSWER: (a) Cc Ww x cc ww

(b) CC Ww x cc Ww(c) Cc Ww x Cc Ww



75. True-breeding yellow guinea pigs crossed with true-breeding white ones produce only cream-colored offspring. This pattern indicates incomplete dominance. Rough hair is found to be dominant to smooth hair. Give the F1 and F2 genotypic and phenotypic ratios of a cross of a smooth, white guinea pig with a homozygous, rough, yellow guinea pig.ANSWER: F1: rough cream Yy Rr; F2: 3 YY R__ yellow rough, 6 Yy R__ cream rough, 3 yy R__ white rough, 1

YY rr yellow smooth, 2 Yy rr cream smooth, 1 yy rr white smoothDIFFICULTY: Bloom's: ApplyREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


76. In the garden pea, Mendel found that tall (D) plants, green pods (G), and inflated pods (C) were dominant to dwarf (d) plants, yellow pods (g), and constricted pods (c). Given the following genotypes, determine the chances of producing the offspring shown.(a) DD Gg Cc x Dd Gg cc -> DD gg Cc(b) DD Gg Cc x Dd Gg Cc -> tall; green, constricted pods(c) Dd Gg Cc x Dd GG cc -> tall; green, inflated pods(d) Dd Gg Cc x Dd Gg Cc -> D__ G__ cc(e) Dd Gg Cc x Dd gg CC -> D__ G__ C__(f) Dd gg cc x DD Gg cc -> tall, green, inflated pods(g) Dd Gg Cc x Dd Gg Cc -> Dd Gg Cc(h) Dd Gg Cc x Dd Gg Cc -> dd gg ccANSWER: (a) (1/2) (1/4) (1/2) = 1/16

(b) (1) (3/4) (1/4) = 3/16(c) (3/4) (1) (1/2) = 3/8(d) (3/4) (3/4) (1/4) = 9/64(e) (3/4) (1/2) (1) = 3/8(f) (1) (1/2) 0 = 0(g) (2/4) (2/4) (2/4) = 8/64(h) (1/4) (1/4) (1/4) = 1/64





77. In tomatoes, red (R) is dominant to yellow (r), tall (D) is dominant to dwarf (d), and smooth (H) is dominant to peach or hairy (h).(a) How many different genotypes are there in relationship to these three characteristics?(b) How many different phenotypes are there in relationship to these three characteristics?(c) How many different homozygous pure-breeding forms can be produced?ANSWER: (a) 27

(b) 8(c) 8



78. If you were following the inheritance patterns of two different sets ofe multiple alleles located on different chromosomes, how many different possible gametes could be produced if locus 1 had five possible alleles and locus 2 had six alleles?ANSWER: 30 possibilitiesDIFFICULTY: Bloom's: ApplyREFERENCES: 13.7 Complex Variation in TraitsLEARNING OBJECTIVES:


79. Heritable units of information about traits are called __________.ANSWER: genesDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

80. Different molecular forms of the same gene are __________.ANSWER: allelesDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

81. The offspring of a cross between two individuals that breed true for different forms of a trait are __________.ANSWER: hybridsDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

82. An individual that has two dominant alleles for a trait (AA) is __________.ANSWER: homozygous dominantDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.



83. A homozygous recessive where "A" represents the trait has two recessive alleles symbolized by __________.ANSWER: aaDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

84. A(n) __________ is a hybrid, with two nonidentical alleles (Aa).ANSWER: heterozygoteDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

85. __________ refers to an individual's observable traits.ANSWER: PhenotypicDIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES: UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

86. Mendel's monohybrid experiment results led to his law of __________.ANSWER: segregationDIFFICULTY: Bloom's: RememberREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

87. __________ assorts gene pairs of homologous chromosomes independently of gene pairs on all other chromosomes.ANSWER: MeiosisDIFFICULTY: Bloom's: RememberREFERENCES: 13.4 Mendel’s Law of Independent AssortmentLEARNING OBJECTIVES:


Subjective Short Answer

88. Explain how incomplete dominance can result in an apparent “blend.”ANSWER: With incomplete dominance, one allele is not fully dominant over the other, so the heterozygous

phenotype is an intermediate blend of the two homozygous phenotypes. A gene that affects flower color in snapdragons is an example (Figure 13.11). One allele of the gene (R) encodes an enzyme that makes a red pigment. The enzyme encoded by a mutated allele (r) cannot make any pigment. Plants homozygous for the R allele (RR) make a lot of red pigment, so they have red flowers. Plants homozygous for the r allele (rr) make no pigment, so their flowers are white. Heterozygous plants (Rr) make only enough red pigment to tint their flowers pink. A cross between two heterozygous plants yields red-, pink-, and white-flowered offspring in a 1:2:1 ratio.

DIFFICULTY: Bloom's: RememberREFERENCES: 13.5 Beyond Simple DominanceLEARNING OBJECTIVES:

UDOL.STES.16.13.2 - Examine how alleles contribute to traits.



89. Explain what genetic ‘trick’ could have confounded Mendel is his recognition of segregation?ANSWER: If Mendel had picked traits controlled by a pleiotropic gene, he would have found that those traits did

move independently. In that case, the clean segregation observed in his other traits would have been completely absent.

DIFFICULTY: Bloom's: UnderstandREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES:


90. Classically, nature and nurture have been considered as two very separate factors impacting phenotype. Considering what we have learned of methylation, is this always the case?ANSWER: Methylation provides an interesting combination of nature and nurture. On one hand, methylation is

clearly impacted both positively and negatively by what the individual experiences, making it nurture. However, those methylation patterns can be passed through multiple generations and impact them, making it nature.

DIFFICULTY: Bloom's: UnderstandREFERENCES: 13.6 Nature and NurtureLEARNING OBJECTIVES:


91. Consider the work Mendel did with his pea plants. Why is the study of human genetics much more difficult?ANSWER: Compared to peas, humans are a difficult species on which to perform genetics. First, we have a long

generation time making studies of the multiple generations difficult. Second, we produce relatively few offspring which weakens statistical analysis. Third, we can’t ethically be told who to mate with so controlling crosses is difficult. Fourth, we can’t self-fertilize. Fifth, many of our traits do not follow simple Mendelian inheritance patterns. The list goes on and on.

DIFFICULTY: Bloom's: RememberREFERENCES: 13.2 Mendel, Pea Plants, and Inheritance PatternsLEARNING OBJECTIVES:

UDOL.STES.16.13.2 - Examine how alleles contribute to traits.

92. If wire hair (W) is dominant to smooth hair (w), and you find a wire-haired puppy, how would you determine its genotype by a genetic breeding experiment?ANSWER: Perform a testcross between the puppy and a dog with smooth hair.DIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

93. In poultry, rose comb is controlled by a dominant allele, and its recessive allele controls single comb.(a) Give the genotype and phenotype produced from crossing a pure-breeding rose comb chicken with a pure-breeding

single comb chicken.(b) Give the results of the backcross of the F1 hybrid with both pure-breeding parents.ANSWER: (a) Rr, rose

(b) Rr x RR -- all rose, Rr x rr -- 1/2 rose, 1/2 singleDIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.



94. If black fur color is controlled by a dominant allele (B) and brown by its recessive allele (b), give the genotypes of the parents and offspring of a cross of a black male with a brown female that produces 1/2 black offspring and 1/2 brown offspring.ANSWER: Black male (Bb) x brown female (bb)

offspring: black (Bb) brown (bb)DIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES: UDOL.STES.16.13.3 - Demonstrate Mendel’s law of segregation using a monohybrid cross.

95. If 2 spot (S) is dominant to 4 spot (s), give the genotypes for the parents in the following crosses:(a) 2 spot × 2 spot yields 2 spot and 4 spot(b) 2 spot × 4 spot yields only 2 spot(c) 2 spot × 4 spot yields 2 spot and 4 spot(d) 2 spot × 2 spot yields only 2 spot(e) 4 spot × 4 spot yields only 4 spotANSWER: (a) Ss x Ss -- S__ + ss

(b) SS x ss -- Ss(c) Ss x ss -- Ss + ss(d) SS x S__ -- S__(e) ss x -- ss

DIFFICULTY: Bloom's: ApplyREFERENCES: 13.3 Mendel’s Law of SegregationLEARNING OBJECTIVES:



chapter 13 - observing patterns in inherited traits · web viewin the late 1920s, a mutation...

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