Chapter 5 and 6 Practice Test
Name ___________________________
Multiple Choice Identify the choice that best completes the statement or answers the question.
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1. What does the notation Aa mean to geneticists? a. two dominant alleles b. two recessive alleles c. homozygous alleles
d. one dominant allele and one recessive allele
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2. What is a pedigree? a. a chart that tracks which members of a family have a particular trait b. a geneticist who studies
the inheritance of traits in humans c. a picture of all of the chromosomes in a cell d. an allele passed from parent to
child on a sex chromosome
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3. Which nitrogen base in RNA is NOT part of DNA? a. adenine b. guanine c. cytosine d. uracil
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4. Where does protein synthesis take place? a. in the ribosomes in the nucleus of the cell b. on the ribosomes in the
cytoplasm of the cell c. in the chromosomes in the nucleus of the cell d. on the chromosomes in the cytoplasm of the
cell
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5. Cloning results in two organisms that are a. both adult mammals. b. produced from cuttings. c. genetically similar.
d. genetically identical.
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6. What happens during meiosis? a. Two sex cells combine. b. Chromosome pairs separate and are distributed into new
sex cells. c. Each sex cell copies itself to form four new chromosomes. d. Chromosome pairs remain together when
new sex cells are formed.
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7. Why does height in humans have such a wide variety of phenotypes? a. Height is controlled by at least four genes.
b. The gene for height has only two alleles. c. Height is controlled by sex-linked genes. d. Height is controlled by a
recessive allele.
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8. Both parents of a child have type A blood. What might their child’s blood type be?
a. Type A only b. Type A or type B c. Type A or type O d. Type A or type AB
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9. Which of these is an example of the benefits of genetic engineering?
a. cross-breeding to create disease-resistant crops b. creating human insulin to treat people with diabetes c. analyzing
karyotypes and pedigree charts d. growing a new plant from a cutting
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10. What does the notation AA mean to geneticists? a. two dominant alleles b. heterozygous alleles c. at least one
dominant allele d. one dominant and one recessive allele
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11. A purebred chicken with white feathers is crossed with a purebred chicken that has black feathers. Each of their offspring
has both black and white feathers. Why does this happen? a. Both alleles for feather color are dominant. b. Both alleles
for feather color are recessive. c. The alleles for feather color are neither dominant nor recessive. d. Several alleles
work together to determine the trait.
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12. Down syndrome most often occurs when a. a person inherits a recessive allele. b. chromosomes fail to separate
properly during meiosis. c. sickle-shaped cells become stuck in blood vessels. d. blood fails to clot properly.
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13. Hemophilia is caused by a(n)
d. codominant allele.
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14. Which combination of sex chromosomes results in a male human being? a. XX b. YY c. XY d. either XX or YY
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15. An organism that has two identical alleles for a trait is a. codominant. b. tall. c. homozygous. d. heterozygous.
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16. Which form of selective breeding crosses parents with the same or similar sets of alleles?
a. fertilization b. inbreeding c. hybridization d. cloning
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17. Factors that control traits are called
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18. You are able to tell a person’s sex by looking at his or her karyotype because a karyotype
a. shows sex-linked disorders. b. is a picture of a person’s genes. c. shows a person’s genotype. d. shows the sex
chromosomes.
a. recessive allele on the X chromosome. b. extra chromosome. c. dominant allele.
a. genes. b. purebreds. c. recessives. d. parents.
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19. When sex cells combine to produce offspring, each sex cell will contribute a. one fourth the number of chromosomes in
body cells. b. half the number of chromosomes in body cells. c. the normal number of chromosomes in body cells.
d. twice the number of chromosomes in body cells.
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20. Which term refers to physical characteristics that are studied in genetics?
d. hybrids
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21. What is a karyotype? a. a sex-linked genetic disorder b. a picture of a baby before it is born
chromosomes in a cell d. fluid that surrounds a baby before it is born
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22. A mutation is harmful to an organism if it a. changes the DNA of the organism. b. changes the phenotype of the
organism. c. reduces the organism’s chances for survival and reproduction. d. makes the organism better able to avoid
predators.
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23. An organism’s genotype is its a. genetic makeup. b. feather color. c. physical appearance. d. stem height.
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24. The order of the bases along a gene determines the order in which
a. sugars are put together to form a carbohydrate. b. phosphates are arranged in DNA. c. amino acids are put together
to form a protein. d. chromosomes are arranged in the nucleus.
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25. What does messenger RNA do during protein synthesis? a. copies the coded message from the DNA and carries it into
the cytoplasm b. copies the coded message from the DNA and carries it into the nucleus c. carries amino acids and
adds them to the growing protein d. copies the coded message from the protein and carries it into the nucleus
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26. What is a mutation? a. any change that is harmful to an organism b. any change in a gene or chromosome c. any
change that is helpful to an organism d. any change in the phenotype of a cell
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27. Sex-linked genes are genes on a. the X chromosome only. b. the Y chromosome only. c. the X and Y chromosomes.
d. all 23 pairs of chromosomes.
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28. If a homozygous black guinea pig (BB) is crossed with a homozygous white guinea pig (bb), what is the probability that
an offspring will have black fur? a. 25 percent b. 50 percent c. 75 percent d. 100 percent
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29. Chromosomes are made up of a. one pair of alleles. b. many traits joined together. c. transfer RNA. d. many genes
joined together.
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30. How does a geneticist use pedigrees? a. to create genetic crosses b. to replicate identical strings of DNA c. to prove
that sex-linked traits are caused by codominant alleles d. to trace the inheritance of traits in humans
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31. What determines the genetic code? a. the order of nitrogen bases along a gene b. the number of nitrogen bases in a
DNA molecule c. the order of amino acids in a protein d. the number of guanine and cytosine bases in a chromosome
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32. An organism’s physical appearance is its a. genotype. b. phenotype. c. codominance. d. heterozygous.
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33. In an attempt to produce a potato that tastes good and also resists disease, plant breeders crossed a potato variety that
tastes good with a variety that resists disease. This technique is an example of
a. genetic engineering. b. inbreeding. c. hybridization. d. cloning.
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34. What does a Punnett square show? a. all the possible outcomes of a genetic cross b. only the dominant alleles in a
genetic cross c. only the recessive alleles in a genetic cross d. all of Mendel’s discoveries about genetic crosses
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35. What do transfer RNA molecules do during protein synthesis? a. copy the coded message from the protein and carry it
into the nucleus b. copy the coded message from the DNA and carry it into the nucleus c. carry amino acids and add
them to the growing protein d. copy the coded message from the DNA and carry it into the cytoplasm
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36. What are multiple alleles? a. more than two genes that control a trait b. three or more forms of a gene that code for a
single trait c. three or more chromosomes that determine a trait d. more than two codominant genes in a chromosome
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37. Why are sex-linked traits more common in males than in females?
a. All alleles on the X chromosome are dominant. b. All alleles on the Y chromosome are recessive. c. A recessive
allele on the X chromosome will always produce the trait in a male. d. Any allele on the Y chromosome will be
codominant with the matching allele on the X chromosome.
a. traits b. offspring c. generations
c. a picture of the
Chapter 5 and 6 Practice test pages 3 and 4
Name ____________________________
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38. Each individual has unique fingerprints. What might you conclude about the inheritance of fingerprint patterns?
a. Fingerprint patterns are sex-linked genes. b. Fingerprint patterns are determined by multiple genes. c. Fingerprint
patterns are influenced by environmental factors. d. Fingerprint patterns are determined by multiple alleles on the same
gene.
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39. Scientists call an organism that has two different alleles for a trait a a. hybrid. b. trait. c. purebred. d. factor.
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40. A carrier is a person who has a. one recessive and one dominant allele for a trait. b. two recessive alleles for a trait.
c. two dominant alleles for a trait. d. more than two alleles for a trait.
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41. The different forms of a gene are called a. alleles. b. factors. c. masks. d. traits.
Modified True/False
Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true.
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42. A male is represented by a square in a pedigree. _________________________
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43. When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were short. _______________
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44. A Punnett square shows all the possible combinations of alleles resulting from a cross. _________________________
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45. The technique called cloning produces an organism that is genetically identical to its parent. _____________________
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46. A hybrid is the offspring of parents that have different alleles for a trait. _________________________
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47. Even if a gene has multiple alleles, a person cannot have more than three of those alleles. _________________________
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48. The number of DNA bases along a gene specifies the type of protein that will be produced. ______________________
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49. An organism’s phenotype is its allele combinations. _________________________
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50. A genetic counselor can help explain the risks of having a child with a disorder to couples who have a family history of
genetic disorders. __________________
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51. Traits that have many different phenotypes, such as height and skin color, are often controlled by a single gene.
_________________________
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52. Chromosomes carry genes from parents to offspring. _________________________
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53. A pea plant that is heterozygous for tall stems has the alleles Tt. _________________________
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54. Sex-linked traits that are controlled by recessive alleles are more likely to show up in males. ______________________
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55. A genetic disorder in which an abnormal form of hemoglobin is produced is hemophilia. _________________________
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56. The sex cells produced by meiosis have twice the number of chromosomes as the parent cells. _____________________
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57. A person’s environment can affect his or her genotype for certain traits, such as height. _________________________
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58. Down syndrome can be diagnosed using a karyotype. _________________________
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59. Transfer RNA carries coded messages from the nucleus to the cytoplasm. _________________________
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60. To create bacteria that produce insulin, a section of DNA is inserted into a bacterium’s chromosome. _____________
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61. A mutation in a sex cell can be passed to offspring. _________________________
Completion Complete each statement.
62. A(n) ____________________ organism is the offspring of many generations of organisms that have the same trait.
63. A chart used to predict results of genetic crosses is known as a(n) ____________________.
64. If all of the sex cells of an organism have the T allele, the genotype of that organism must be ____________________.
65. An organism that has two dominant or two recessive alleles is said to be ____________________ for that trait.
66. A person’s surroundings, or ____________________, can change the effects of a person’s genes.
67. A set of three bases codes for one specific ____________________ in a protein.
68. Alleles that are neither dominant nor recessive produce an inheritance pattern known as ____________________.
69. Genes are carried from parents to their offspring on structures called ____________________.
70. The genetic code is found in the order of nitrogen ____________________ along a gene.
71. If you see two DNA fingerprints that are exactly the same but come from different individuals, you know you are
looking at the DNA fingerprints of ______________.
72. A gene from one organism is inserted into the DNA of another organism in the process known as __________________.
73. The three alleles on the single gene that controls blood type are said to be ____________________ alleles.
74. A section of DNA has the base sequence TGAG. The corresponding section of a messenger RNA molecule will have the
base sequence ___________________.
75. In pea plants, the tall-stem allele and the short-stem allele are different forms of the same ____________________.
76. An organism can be heterozygous for some traits and ____________________ for others.
77. ____________________ RNA adds amino acids to a growing protein.
78. If D represents the dominant allele of a gene, then ____________________ represents the recessive allele.
79. The process in which a parent cell divides twice to produce sex cells is called ____________________.
80. A gene is said to have multiple alleles if it has more than ____________________ alleles.
81. When many genes control a trait, the trait will show a large number of ____________________.
82. If a(n) ____________________ allele is present, its trait will appear in the organism.
83. A(n) ____________________ is used to track the occurrence of a trait in a family.
84. The substitution of one base for another during DNA replication is an example of a(n) ____________________.
85. A karyotype can be used to determine the number of ____________________ in a person’s cells.
86. The chromosomes in a pair may each have different ____________________ for each gene.
87. In a cross between two hybrid Tt pea plants, ____________________ percent of the offspring will be Tt.
88. A carrier is a person who has one ____________________ allele for a trait.
89. An egg that is fertilized by a sperm cell with a(n) ____________________ chromosome will develop into a female.
Chapter 5 and 5 Practice Test, Pages 5 and 6
Name __________________________________
Short Answer Use the diagram to answer each question.
90. Identify structure E and describe its function.
91. Identify structure D and state where it is made.
92. Identify structure A and state what it is made of.
93. Identify structures B and C.
94. What are the three nitrogen bases in transfer RNA that pair with bases A-G-U in messenger RNA?
95. If one of the nitrogen bases on structure D were replaced by a different base, what effect might that have on protein
synthesis?
Use the diagram to answer each question.
96. Which individuals neither have the trait nor are carriers?
97. Could the trait that is traced by this pedigree be sex-linked? Explain why or why not.
98. What do the circles in the pedigree represent? What do the squares represent?
99. Which individuals have the trait that is traced by the pedigree?
100. Which pairs of individuals in the pedigree have children?
101. Which individuals are carriers of the trait that is traced by the pedigree?
Use the diagram to answer each question.
102. Which trait—white flowers or purple flowers—is controlled by a dominant allele? Which is controlled by a recessive
allele? How do you know?
103. In the F2 generation, what percent of the offspring have white flowers? What are the genotypes of the white-flowered
offspring?
104. In the F2 generation, what percent of the offspring have purple flowers? What is the genotype of the purple-flowered
offspring?
105. Suppose one of the parents of the F2 generation had been ww instead of Ww. What percent of the offspring would have
purple flowers? What percent would have white flowers?
106. In the F1 generation, what is the genotype of the offspring? What is their phenotype?
107. In which generation are the parents purebred? In which generation are they hybrids?
Essay
108. Explain the function of meiosis.
109. Describe what messenger RNA and transfer RNA do during protein synthesis.
110. Is it possible for a son to inherit an allele on an X chromosome from his father? Explain why or why not.