Chapter 7 WORD file

1. D) alleles.
1. Most genes come in alternative forms called:
A) chromosomes.
B) gametes.
C) recessives.
D) alleles.
E) dominants.
2. E) If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 25% chance of having the syndrome.
2. How can an individual whose parents did not have the “fish odor syndrome” trait inherit that trait?
A) The “fish odor syndrome” trait is inherited extra-genetically.
B) If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 50% chance of having the syndrome.
C) If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 100% chance of having the syndrome.
D) Under the circumstances outlined above, the “fish odor syndrome” cannot be inherited.
E) If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 25% chance of having the syndrome.
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3. C) the baby has inherited many alleles from his father that work together to shape the baby’s nose.
3. If a baby has “his father’s nose,” it’s because:
A) the baby has been cobbled together from a bunch of used parts.
B) the baby has not inherited the “suppress father’s nose allele” from his mother.
C) the baby has inherited many alleles from his father that work together to shape the baby’s nose.
D) the baby has inherited the “father’s nose” allele from his father.
E) the baby has inherited the “father’s nose” allele from his mother.
4. D) over 9,000
4. How many human traits are controlled by a single gene?
A) 0
B) about 100
C) 2
D) over 9,000
E) over 100,000
5. D) the widow’s peak hairline
5. Which of the following is a single-gene trait?
A) brown hair
B) blue eyes
C) height
D) the widow’s peak hairline
E) All of the above are single-gene traits.
6. E) increased body size in cattle.
6. Without knowing the genetic basis, humans have selectively bred for:
A) unattached earlobes.
B) straight hairline.
C) transgenic tomatoes.
D) cleft chins.
E) increased body size in cattle.
7. A) a cleft chin
7. Virtually everyone with __________________ has a parent that exhibits the same trait.
A) a cleft chin
B) freckles
C) color-blindness
D) phenylketonuria
E) sickle-cell disease
8. D) garden peas.
8. Gregor Mendel performed his famous experiments on:
A) hawkweed.
B) humans.
C) pigeons.
D) garden peas.
E) Darwin’s finches.
9. D) He understood basic concepts about DNA replication.
9. Which of the following was NOT true of Gregor Mendel?
A) His primary research system was the pea plant.
B) He was an Austrian monk.
C) He lived in the 19th century.
D) He understood basic concepts about DNA replication.
E) He developed the first theory about how traits are inherited.
10. E) a chromosome
10. Which of the following did Gregor Mendel never see?
A) a pea
B) an F2 generation
C) a stamen
D) a hybrid
E) a chromosome
11. E
11. Peas (Pisum sativum) were well suited for Mendel’s breeding experiments for all of the following reasons except:
A) peas exhibit variations in a number of observable characteristics, such as flower color and seed shape.
B) Mendel and his staff could control the pollination between different pea plants.
C) it is easy to obtain large numbers of offspring from any given cross.
D) many of the characteristics that vary in pea plants are controlled by single genes.
E) peas have a particularly long generation time.
12. D
12. A plant with pink flowers is allowed to self-pollinate. Generation after generation, it produces pink flowers. This is an example of:
A) incomplete dominance.
B) allopolyploidy.
C) interbreeding.
D) a true-breeding plant.
E) the law of independent assortment.
13. D
13. The law of segregation states that:
A) the transmission of genetic diseases within families is always recessive.
B) the number of chromosomes in a cell is always divisible by 2.
C) an allele on one chromosome will always segregate from an allele on a different chromosome.
D) each of two alleles for a given trait segregate into different gametes.
E) gametes cannot be separate and equal.
14. E
14. Which of the following statements about dominant traits is correct?
A) They increase in frequency over evolutionary time.
B) They are observed more frequently than recessive traits.
C) They are observed one-quarter as frequently as heterozygous traits.
D) They are observed less frequently than recessive traits.
E) None of the above is correct.
15. E
15. A cross between homozygous red-eyed flies and homozygous white-eyed flies results in progeny that all have red eyes. This result demonstrates:
A) the law of independent assortment.
B) a dihybrid cross.
C) the norm of reaction.
D) the blending model of genetics.
E) dominance.
16. E
16. In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for white flowers are crossed, in the offspring:
A) all of the flowers will be purple.
B) three-quarters of the flowers will be purple and one-quarter will be white.
C) half of the flowers will be purple and half will be white.
D) one-quarter of the flowers will be purple and three-quarters will be white.
E) all of the flowers will be white.
17. A
17. A diploid individual with two identical alleles for a particular gene is said to be:
A) homozygous for that gene.
B) homozygous for every gene.
C) heterozygous for every gene.
D) sex-linked dominant.
E) heterozygous for that gene.
18. D
18. In genetics, the separation of alleles or homologous chromosomes during meiosis so that the haploid daughter cells have one allele or the other but never both is also referred to as:
A) Mendel’s first law.
B) segregation.
C) random genetic drift.
D) Both a) and b) are correct.
E) All of the above are correct.
19. A
19. Tay-Sachs, which is a recessive lethal disease, results only when individuals possess two copies of the disease-causing allele. Which of the following statements is true about this disease?
A) Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.
B) All cases of this disease must be caused by new mutations.
C) Heterozygous individuals are more fit than homozygous dominant individuals, so eventually, there will only be heterozygotes in the population.
D) Heterozygous individuals only pass on the dominant copy of the allele to offspring.
E) None of the above is correct.
20. D
20. If a true-breeding, blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant.
A) 75% blue, 25% white
B) 100% blue
C) 100% light blue
D) 100% white
E) There is not enough information to answer this question.
21. D
21. The phenotype of an organism can best be determined by:
A) inbreeding.
B) outbreeding.
C) sequencing its genes.
D) observing the organism.
E) a reciprocal cross.
22. D
22. Albinism (lack of skin and hair pigmentation) is caused by a recessive autosomal allele. A woman and man, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child?
A) It depends on the sex of the child.
B) homozygous dominant
C) It is unknown because not enough information is provided.
D) homozygous recessive
E) heterozygous
23. E
23. How can two pea plants that have different genotypes for seed color be identical in phenotype?
A) Genotype has no relation to phenotype.
B) One of the two plants could be homozygous for the dominant allele while the other could be homozygous for the recessive allele.
C) One of the two plants could be homozygous for the recessive allele while the other could be heterozygous.
D) Seed color in pea plants is not genetically determined.
E) One of the two plants could be homozygous for the dominant allele while the other could be heterozygous.
24. E
24. A true-breeding red rose is repeatedly mated with a true-breeding white rose, and all of their offspring are red. If two of these red offspring are mated, what percentage of their offspring will be red?
A) 60%
B) 100%
C) 25%
D) 50%
E) 75%
25. C
25. In pea plants, tall stem length is dominant to short, and round seed shape is dominant to wrinkled seed shape. If a plant that is homozygous for tall stem and homozygous for wrinkled seeds is allowed to self-fertilize, what proportion of the offspring will have wrinkled seeds and a tall stem?
A) None of the offspring will have wrinkled seeds and a tall stem.
B) 9/16
C) All of the offspring will have wrinkled seeds and a tall stem.
D) 1/2
E) 3/16
26. A
26. Two fruit flies are crossed, resulting in offspring with a 3:1 phenotypic ratio for a particular trait. This suggests:
A) that the parents were both heterozygous for the gene associated with that trait.
B) that one parent had complete dominance for the gene associated with that trait while the other parent had incomplete dominance.
C) that the one parent was heterozygous for the gene associated with that trait and the other parent was homozygous.
D) incomplete dominance.
E) that the parents were both homozygous for the gene associated with that trait.
27. E
27. Cystic fibrosis, which is usually lethal before reproductive ages, is a homozygous recessive disease. Why do cases continue to arise, even though people with the disease rarely live to reproduce?
A) Cystic fibrosis is a multifactorial disorder, and is probably controlled by the action of many genes.
B) Individuals can pass on the alleles in non-genetic ways, including through the sharing of needles.
C) People continue to make unhealthy lifestyle choices.
D) Mosquitoes can transfer the disease from person to person.
E) The harmful allele can reside in heterozygous individuals with few to no negative effects.
28. C
28. Gray hair in voles (H) is dominant to brown hair (h). Short claws (C) are dominant to long claws (c). What is the probability that the offspring of the cross HhCc × HHcc will have gray hair and long claws?
A) 37.5%
B) 56.25%
C) 50%
D) 0%
E) 25%
29. A
29. In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered?
A) 0%
B) 100%
C) 25%
D) 50%
E) It depends on whether the traits are linked.
30. E
30. The test-cross:
A) makes it possible to determine the genotype of an individual of unknown genotype who exhibits the dominant version of a trait.
B) is a cross of an individual whose genotype for a trait is not known with an individual homozygous-recessive for the trait.
C) sometimes requires the production of multiple offspring in order to reveal the genotype of an individual whose genotype is unknown.
D) a) and b) are both correct.
E) a), b), and c) are correct.
31. E
31. In pea plants, the allele for purple flower color is dominant to the allele for white flower color. If you were to perform a test-cross to determine the genotype of a purple-flowered plant, you would expect the percentage of purple-flowered progeny to be _________ if the plant is homozygous and _____________ if the plant is heterozygous.
A) 50%; 25%
B) 50%; 100%
C) 100%; 25%
D) 75%; 75%
E) 100%; 50%
32. C
32. Which of the following statements is true regarding pedigree analysis?
A) Squares represent females, while circles represent males.
B) Horizontal lines connect siblings.
C) Darkened shapes always represent individuals with the trait being traced.
D) The length of the vertical lines is dependent on the relatedness coefficient between two individuals.
E) White shapes always represent heterozygous individuals.
33. E
33. Autosomal dominant traits:
A) appear in equal frequency in males and females.
B) do not skip generations
C) gradually replace autosomal recessive traits.
D) All of the above are correct.
E) a) and b) are both correct.
34. A
34. Autosomal recessive traits:
A) can skip generations.
B) occur in 1/4 of all offspring.
C) are exhibited only in the offspring of two heterozygous parents.
D) occur more frequently in females than males.
E) All of the above.
35. B
35. Assuming that a particular disorder is caused by an allele of a single gene, what feature of a pedigree would allow one to conclude that the disorder was caused by a dominant allele?
A) Two unaffected parents have an affected child.
B) Two affected parents have an unaffected child.
C) Two unaffected parents have an unaffected child.
D) An affected mother only has affected sons.
E) All of the descendants of a particular affected person are also affected.
36. B
36. A situation in which the heterozygote offspring of two homozygotes show a phenotype intermediate between those of the parents is called:
A) a single-gene trait.
B) incomplete dominance.
C) heterozygote superiority.
D) a test-cross.
E) multiple allelism.
37. B
37. Heterozygous individuals:
A) always exhibit the same phenotype as homozygous-dominant individuals.
B) can have greater fitness than homozygous individuals.
C) always come from the cross of parents that each are homozygous for a different allele.
D) a) and b) are correct.
E) a) and c) are correct.
38. B
38. The offspring from each cross done in Mendel’s pea experiments always looked like one of the two parental varieties because:
A) each allele affected phenotypic expression.
B) one allele showed complete dominance over the other.
C) many different genes interacted to produce the F1 phenotype.
D) the traits blended together because of crossing-over in meiosis.
E) many different genes interacted to produce the parental phenotype.
39. E
39. Flower color in snapdragons is an example of incomplete dominance. When a red-flowered plant is crossed with a white-flowered plant, the offspring have pink flowers. If a pink-flowered plant is crossed with another pink-flowered plant, their offspring will be:
A) 25% white and 75% red.
B) all red.
C) all pink.
D) 50% pink and 50% red.
E) 25% red, 50% pink, and 25% white.
40. D
40. In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers.
A) pink
B) no
C) red
D) white
E) purple
41. B
41. In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, CW, that produces no pigment, and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce _________________ flowers.
A) no
B) pink
C) white
D) two kinds of
E) red
42. B
42. If two individuals who are heterozygous for the sickle-cell disease mate, their offspring:
A) will all have the genotype HbSHbA.
B) will have a one-quarter chance of being a sickle-cell free homozygote.
C) will all be heterozygous for the sickle-cell disease.
D) will all have the sickle-cell disease.
E) None of the above is correct.
43. C
43. The ABO blood type system in humans is an example of:
A) balanced polymorphism and codominance.
B) codominance but not multiple alleles.
C) multiple alleles and codominance.
D) multiple alleles but not codominance.
E) balanced polymorphism but not codominance.
44. E
44. The ABO blood type system in humans is a system that contains ________ alleles that produce __________ different phenotypes.
A) three; three
B) four; three
C) three; six
D) four; four
E) three; four
45. D
45. Some genes, such as the human ABO blood groups, have more than two alleles. For these genes:
A) a greater proportion of the individuals must be heterozygous than homozygous.
B) some individuals can be triply heterozygous.
C) normal dominance relationships are not possible.
D) individuals can only possess two alleles.
E) All of the above are true.
46. A
46. Jay has type O blood, and his brother Alon has type AB blood. What are the genotypes of these boys’ parents?
A) IAi and IBi
B) ii and IBi
C) IAIA and IBi
D) IAi and IBIB
E) ii and ii
47. A
47. Which of the following pairings, indicated by letters referring to blood type phenotypes, CANNOT produce a child with type B blood?
A) O x O
B) O x AB
C) B x O
D) A x B
E) All of the above could produce a child with type B blood.
48. E
48. Mary, who has type O blood, is expecting a child with her husband, who has type B blood. Mary’s husband’s father has type A blood. What is the probability that the child will have type O blood?
A) 75%
B) 0%
C) 25%
D) 100%
E) 50%
49. A
49. A woman with type B blood and a man with type A blood could have children with which of the following phenotypes?
A) A, B, AB, or O
B) A, B, or O
C) AB only
D) AB or O
E) O only
50. D
50. Which of the following is NOT a continuously varying trait?
A) eye color
B) height
C) weight
D) sickle-cell disease
E) skin color
51. C
51. Which term refers to the genetic control of continuously varying traits such as height?
A) incomplete dominance
B) codominant
C) polygenic
D) multi-allelic
E) pleiotropic
52. B
52. In the case of Mendel’s peas, a single gene determined the height of the plant. However, in humans, adult height is influenced by many genes. A trait such as human height is said to be:
A) incompletely dominant.
B) polygenic.
C) codominant.
D) multi-allelic.
E) pleiotropic.
53. A
53. The impact of a single gene on more than one characteristic is called:
A) pleiotropy.
B) polygenic inheritance.
C) codominance.
D) incomplete dominance.
E) epistasis.
54. D
54. The same genetic condition that causes sickle-cell anemia can also protect against:
A) HIV-AIDS.
B) cholera.
C) yellow fever.
D) malaria.
E) hemophilia.
55. B
55. The SRY gene:
A) causes circular red blood cells to resist malaria.
B) causes fetal gonads to develop as testes shortly after fertilization.
C) protect humans from somatic respiratory yeasts.
D) causes sickle-shaped red blood cells to resist malaria.
E) causes fetal gonads to develop as ovaries shortly after fertilization.
56. A
56. Most, if not all, genes are:
A) pleiotropic.
B) heterozygous.
C) codominant.
D) multi-allelic.
E) sex-linked.
57. B
57. The sickle-cell allele is considered to be pleiotropic because:
A) it is involved in a continuously varying trait: the amount of oxygen delivery.
B) it has at least two effects: disrupting oxygen delivery and protecting against malaria.
C) it is involved in a continuously varying trait: the amount of resistance to malaria.
D) it is codominant, in that heterozygotes have both circular and sickled red blood cells.
E) it has at least two effects: promoting oxygen delivery and protecting against malaria.
58. A
58. In humans, X-linked traits:
A) occur on the X chromosome.
B) are passed from fathers to their sons.
C) are more common than autosomal traits.
D) occur more frequently in females.
E) All of the above are true.
59. A
59. Sex-linked traits:
A) often are expressed in different frequencies in males and females.
B) are coded for by genes on the Y-chromosome only.
C) occur in females but not males.
D) occur in males but not females.
E) are coded for by genes on the autosomes.
60. C
60. All genetically normal humans have:
A) eight toes.
B) 46 autosomes.
C) 44 autosomes.
D) Two pairs of 22 autosomes, a Y chromosome, and an X chromosome.
E) 23 chromosomes.
61. D
61. In many species of birds, males are XX and females are XZ. With birds like this, who is most likely to display a sex-linked recessive trait?
A) There is no Y chromosome so they are not affected by sex-linked recessive traits.
B) Males and females are equally likely to display a sex-linked recessive trait.
C) The gender that’s incubated at a higher temperature.
D) females
E) males
62. A
62. A male with an X-linked recessive disorder mates with a female that is a carrier for this same X-linked recessive disorder. Which of the following is the correct expected frequency of this disorder in their children?
A) 50% frequency in both the sons and the daughters
B) 50% frequency in the sons
C) 100% frequency in the daughters
D) 100% frequency in the sons
E) 50% frequency in the daughters
63. E
63. Is it possible for a woman to have a X-linked recessive trait? If it is, how can this occur?
A) No, women cannot have X-linked recessive traits because they are all recessive and women have two X chromosomes.
B) Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is homozygous for the trait.
C) Yes, a woman can have an X-linked recessive trait if both her father has the trait and her mother is heterozygous for the trait.
D) Yes, a woman can have an X-linked recessive trait if her mother is homozygous for the trait.
E) Both b) and c) are correct.
64. A
64. Phenylketonuria is a genetic disorder that:
A) causes the inability to convert phenylalanine to tyrosine.
B) causes too many copies of phenylalanine to be added to protein chains.
C) causes the build up of tyrosine in the system.
D) causes the inability to convert tyrosine to phenylalanine.
E) causes too few copies of tyrosine to be added to protein chains.
65. D
65. Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional.
A) arginine; phenylalanine
B) phenylalanine; arginine
C) tyrosine; phenylalanine
D) phenylalanine; tyrosine
E) None of the above is correct.
66. B
66. Phenylketonuria is a good example of the environmental effects on phenotype because:
A) some people carry two copies of a mutant version of the gene that is supposed to produce the enzyme that converts phenylalanine to tyrosine.
B) its adverse effects can be avoided by limiting the amount of phenylalanine in the diet.
C) its adverse effects can be avoided by increasing the amount of phenylalanine in the diet.
D) its beneficial effects can be increased by limiting the amount of phenylalanine in the diet.
E) its adverse effects can be avoided by increasing the amount of tyrosine in the diet.
67. A
67. Phenotypes are generally a product of:
A) the genotype in combination with the environment.
B) multiple alleles at the same gene locus.
C) two or more genes in combination with each other.
D) the genotype.
E) the environment.
68. A
68. The failure of a seedling to turn green if grown in the dark is an example of:
A) interaction between genotype and environment.
B) incomplete dominance.
C) interaction between codominant alleles.
D) pleiotropy.
E) continuous variation.
69. D
69. When genetically based traits are inherited independently from each other, this is known as:
A) linkage.
B) multi-allelism.
C) polygenism.
D) Mendel’s law of independent assortment.
E) pleitropy.
70. E
70. Mendel’s law of independent assortment states that the alleles at one locus separate independently of those at other loci. This law does not apply:
A) if recombination between the two loci occurs.
B) to identical twins.
C) to genes that influence the same character.
D) to autosomal genes.
E) to genes located close together on the same chromosome.
71. B
71. How many unique haploid gametic genotypes could be produced through independent assortment by an organism with the diploid genotype AABbCCDdEe?
A) 2
B) 8
C) 16
D) 4
E) 1
72. C
72. Pedram and Monica are both heterozygous for the widow’s peak trait. Individuals who have two copies of the widow’s peak allele exhibit a sharp, pointed hairline. What is the probability that the couple’s first three children will all have widow’s peaks?
A) 1/12
B) 1/3
C) 1/64
D) 3/4
E) 1/4
73. D
73. The MOST important reason that Mendel’s law of independent assortment is NOT universally true is that:
A) genes are made of DNA.
B) genes are almost always pleiotropic.
C) half of your genes are inherited from your mother and half from your father.
D) genes are carried on chromosomes.
E) some genes are sex-linked.
74. B
74. Linked genes:
A) never show crossing over.
B) are on the same chromosome.
C) never have multiple alleles.
D) have alleles that assort independently of each other.
E) must be immediately adjacent to each other on the same chromosome.
75. C
75. We say that genes are linked when:
A) they contain multiple alleles.
B) they assort independently.
C) they are located near each other on a single chromosome.
D) they are responsible for producing the same protein.
E) they produce a balanced polymorphism.
76. E
76. Genes that are _____________ do not assort independently, but they may recombine by crossing over.
A) continuously variable
B) pleiotropic
C) polygenic
D) epistatic
E) linked
77. C
77. When crossing-over occurs, _______________ genes usually stay together.
A) multi-allelic
B) independently assorting
C) linked
D) pleiotropic
E) sex-linked
78. The domestication of plants and animals involved breeding individuals with desirable traits in order to amplify these traits. Although heredity could be observed, its mechanism was unclear until it was described by Gregor Mendel in the 1800s.
78. Describe the relationship between plant and animal domestication and an awareness of heredity.
C- homozygous for the recessive allele.
79. At locus a, the individual bearing these two homologous chromosomes is

PICTURE
A- homozygous for the dominant allele.

B- heterozygous for the dominant phenotype.

C- homozygous for the recessive allele.

D- heterozygous for the recessive allele.

E- homozygous for the dominant phenotype.

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