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Midterm Exam 08-09 B

Modified True/False
Indicate whether the sentence or statement is true or false.
 

1. 
When Mendel crossed purebred short plants with purebred tall plants, all of the offspring were short.

 

2. 
A hybrid is the offspring of parents that have different alleles for a trait.

 

3. 
A pea plant that is heterozygous for tall stems has the alleles Tt.

 

4. 
A Punnett square shows all the possible combinations of alleles in parents.

 

5. 
An organism’s physical appearance is its phenotype.

 

6. 
The sex cells produced by meiosis have twice the number of chromosomes as the parent cells.

 

7. 
Chromosomes carry genes from parents to offspring.

 

8. 
The number of DNA bases forms a genetic code.

 

9. 
Transfer RNA carries coded messages from the nucleus to the cytoplasm.

 

10. 
A mutation in a sex cell can be passed to offspring.

 

11. 
Even if a gene has multiple alleles, a person cannot have more than three of those alleles.

 

12. 
Trait such as height and skin color that have many different phenotypes are often controlled by a single gene.

 

13. 
A person’s environment can affect his or her genotype for certain traits, such as height.

 

14. 
Sex-linked traits that are controlled by recessive alleles are more likely to show up in males.

 

15. 
A male is represented by a square in a pedigree.

 

16. 
A genetic disorder in which an abnormal form of hemoglobin is produced is hemophilia.

 

17. 
A doctor can look at the chromosomes of a cell in a karyotype.

 

18. 
The technique called cloning produces an organism that is genetically identical to its parent.

 

19. 
Except for identical twins, all people have the same DNA.

 

20. 
The goal of DNA fingerprinting is to prepare an encyclopedia that shows the DNA sequence of every gene.

 

21. 
The gradual change in a species over time is called adaptation.

 

22. 
Through natural selection, harmful variations gradually accumulate in a species.

 

23. 
When some members of a species become geographically isolated, they are less likely to form a new species.

 

24. 
An empty space called a cast is formed when an organism buried in sediments dissolves.

 

25. 
In sedimentary rock, the youngest fossils are usually found in the deepest layers.

 

26. 
The largest span of time in the Geologic Time Scale is Precambrian Time.

 

27. 
Darwin thought that species evolved rapidly.

 

28. 
The theory of punctuated equilibria proposes that species evolve through small changes over a long time.

 

29. 
The more similar the DNA sequences of two species are, the more closely related the species are.

 

30. 
On a branching tree, a species is more closely related to a species on the same branch than to one on a separate branch.

 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

31. 
What did Gregor Mendel do to study different characteristics in his genetics experiments?
a.
He studied only asexual animals.
b.
He studied only self-pollinating plants.
c.
He cross-pollinated plants.
 

32. 
In Mendel’s experiments, what proportion of the plants in the F2 generation had a trait that had been absent in the F1 generation?
a.
none
b.
one fourth
c.
half
 

33. 
Factors that control traits are called
a.
genes.
b.
purebreds.
c.
recessives.
 

34. 
Scientists call an organism that has two different alleles for a trait a
a.
hybrid.
b.
trait.
c.
purebred.
 

35. 
What does the notation TT mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
at least one dominant allele
 

36. 
What does the notation Tt mean to geneticists?
a.
two dominant alleles
b.
one dominant allele and one recessive allelle
c.
two recessive alleles
 

37. 
What is probability?
a.
the actual results from a series of events
b.
the likelihood that a particular event will occur
c.
the way the results of one event affect the next event
 

38. 
What did Mendel predict was the probability of producing a tall plant from a genetic cross of two hybrid tall plants?
a.
one in four
b.
two in four
c.
three in four
 

39. 
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
 

40. 
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.
75 percent
b.
50 percent
c.
100 percent
 

41. 
An organism’s physical appearance is its
a.
genotype.
b.
phenotype.
c.
codominance.
 

42. 
What does codominance mean in genetics?
a.
Both alleles are dominant.
b.
Both alleles are recessive.
c.
The alleles are neither dominant nor recessive.
 

43. 
What is the chromosome theory of inheritance?
a.
Chromosomes are carried from parents to offspring on hybrids.
b.
Genes are carried from parents to offspring on chromosomes.
c.
Hybrid pairs of chromosomes combine to form offspring.
 

44. 
Walter Sutton discovered that the sex cells of grasshoppers have exactly
a.
twice the number of chromosomes found in the body cells.
b.
half the number of chromosomes found in the body cells.
c.
12 times the number of chromosomes found in the body cells.
 

45. 
What happens during meiosis?
a.
Each sex cell loses half of its chromosomes.
b.
Chromosome pairs separate to form new sex cells.
c.
Each sex cell copies itself to form four new chromosomes.
 

46. 
When sex cells combine to produce offspring, each sex cell will contribute
a.
one fourth of the normal number of chromosomes.
b.
half the normal number of chromosomes.
c.
the normal number of chromosomes.
 

47. 
What is 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
 

48. 
The order of the bases along a gene determines the order in which
a.
sugars are put together to form a carbohydrate.
b.
genes are arranged on a chromosome.
c.
amino acids are put together to form a protein.
 

49. 
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
 

50. 
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
 

51. 
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
 

52. 
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.
 

53. 
Which term refers to physical characteristics that are studied in genetics?
a.
traits
b.
offspring
c.
generations
 

54. 
The different forms of a gene are called
a.
alleles.
b.
factors.
c.
masks.
 

55. 
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
 

56. 
What does the notation tt mean to geneticists?
a.
two dominant alleles
b.
two recessive alleles
c.
at least one dominant allele
 

57. 
An organism’s genotype is its
a.
genetic makeup
b.
feather color
c.
physical appearance
 

58. 
Which nitrogen base in RNA is NOT part of DNA?
a.
uracil
b.
adenine
c.
guanine
 

59. 
An organism that has two identical alleles for a trait is
a.
codominant.
b.
tall.
c.
homozygous.
 

60. 
A heterozygous organism has
a.
two identical alleles for a trait.
b.
only one allele for a trait.
c.
two different alleles for a trait.
 

61. 
Which of these traits is controlled by a gene with multiple alleles?
a.
widow’s peak
b.
blood type
c.
smile dimples
 

62. 
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
 

63. 
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.
 

64. 
What controls variations in skin color among humans?
a.
a person’s diet
b.
at least three genes
c.
multiple alleles of a single gene
 

65. 
Which of these human traits is altered by variations in environment?
a.
hairline
b.
height
c.
smile dimples
 

66. 
What factors can affect a person’s height?
a.
genes only
b.
environmental factors only
c.
both genes and environmental factors
 

67. 
Which combination of sex chromosomes results in a male human being?
a.
XX
b.
YY
c.
XY
 

68. 
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.
 

69. 
How does a geneticist use pedigrees?
a.
to replicate identical strings of DNA
b.
to prove that sex-linked traits are caused by codominant alleles
c.
to trace the inheritance of traits over generations of families
 

70. 
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
 

71. 
Genetic disorders are caused by
a.
pedigrees.
b.
mutations.
c.
dominant alleles.
 

72. 
Which genetic disorder causes the body to produce unusually thick mucus in the lungs and intestines?
a.
hemophilia
b.
Down syndrome
c.
cystic fibrosis
 

73. 
What is a karyotype?
a.
blood from a newborn baby
b.
a picture of a baby before it is born
c.
a picture of the chromosomes in a cell
 

74. 
How can genetic counselors predict genetic disorders?
a.
by studying karyotypes and pedigree charts
b.
by taking pictures of a baby before it is born
c.
by exploring new methods of genetic engineering
 

75. 
Cloning results in two organisms that are
a.
genetically similar.
b.
genetically identical.
c.
produced from cuttings.
 

76. 
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
 

77. 
No two people have the same DNA, except for
a.
identical twins.
b.
sisters.
c.
crime suspects.
 

78. 
How do police use DNA fingerprinting to help solve crimes?
a.
by proving that a suspect’s blood type matches evidence in a crime
b.
by showing that a suspect’s fingerprints are at a crime scene
c.
by comparing a suspect’s DNA patterns with evidence from a crime scene
 

79. 
What is the purpose of the Human Genome Project?
a.
to identify the DNA sequence of every gene in the human genome
b.
to clone every gene on a single chromosome in human DNA
c.
to splice every gene on a single chromosome in human DNA
 

80. 
What is a genome?
a.
all the cells produced during meiosis
b.
all the plasmids from splicing DNA in a cell
c.
all the DNA in one cell of an organism
 

81. 
One parent of a child has type A blood and the other has type B blood. What is the child’s blood type?
a.
Type A
b.
Type B
c.
Type AB
 

82. 
Sex-linked genes are genes on
a.
the X chromosome only.
b.
the Y chromosome only.
c.
the X and Y chromosomes.
 

83. 
Which form of selective breeding crosses genetically different individuals in an attempt to keep the best traits of both parents?
a.
genetic engineering
b.
inbreeding
c.
hybridization
 

84. 
Which form of selective breeding crosses parents with the same or similar sets of alleles?
a.
fertilization
b.
inbreeding
c.
hybridization
 

85. 
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.
 

86. 
What must occur for a girl to be colorblind?
a.
Each parent must be colorblind.
b.
Each parent must have the dominant allele for colorblindness.
c.
Each parent must have the recessive allele for colorblindness.
 

87. 
Hemophilia is caused by a(n)
a.
recessive allele on the X chromosome.
b.
extra chromosome.
c.
dominant allele.
 

88. 
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.
 

89. 
What genetic disorder results in abnormally shaped blood cells?
a.
cystic fibrosis
b.
hemophilia
c.
sickle-cell disease
 

90. 
What procedure helps doctors diagnose a genetic disorder before a baby is born?
a.
genetic engineering
b.
selective breeding
c.
amniocentesis
 

91. 
A species is a group of similar organisms that
a.
can mate with each other and produce fertile offspring.
b.
can live together on an island.
c.
can migrate to an island from the mainland.
 

92. 
What did Darwin infer from his observations of organisms in South America and the Galapagos Islands?
a.
A small number of different plant and animal species had come to the Galapagos Islands from the mainland.
b.
A small number of different plant and animal species had come to the mainland from the Galapagos Islands.
c.
The organisms on the Galapagos Islands were completely unrelated to mainland organisms.
 

93. 
Differences between members of the same species are called
a.
predators.
c.
selections.
b.
variations.
 

94. 
What is the role of genes in evolution?
a.
Parents with recessive genes die from overproduction.
b.
The genes of most surviving parents have only dominant alleles.
c.
Only traits that are controlled by genes can be acted on by natural selection.
 

95. 
Which of these is one of the main ways that a new species forms?
a.
Cross-breeding occurs within the species.
b.
A group is separated from the rest of the species.
c.
Competition occurs between members of the species.
 

96. 
Which of these illustrates the impact of continental drift on the formation of new species?
a.
Marsupial mammals adapt better in North America than in Australia.
b.
Most mammals in Australia are marsupials, but few marsupials exist on other continents.
c.
Australia has fewer marsupials than South America.
 

97. 
What are fossils?
a.
molds and casts of organisms that live today
b.
drawings of ancient animals and other organisms
c.
the preserved remains or traces of organisms that lived in the past
 

98. 
How do most fossils form?
a.
An insect becomes trapped in amber.
b.
An entire organism becomes frozen in ice.
c.
A dead organism becomes buried in sediment.
 

99. 
How do scientists determine the actual age of fossils?
a.
relative dating
c.
sedimentary dating
b.
absolute dating
 

100. 
What evidence is most important when using relative dating?
a.
the half-life of a radioactive element
b.
the position of fossils in sedimentary rock layers
c.
the position of sediment in petrified rock
 

101. 
Which term refers to a species that no longer has any living members?
a.
molded
c.
extinct
b.
fossilized
 

102. 
How long is Precambrian Time in the Geologic Time Scale?
a.
4 million years
c.
4 billion years
b.
4.6 million years
 

103. 
What theory proposes that evolution occurs steadily in tiny changes over long periods of time?
a.
gradualism
c.
natural selection
b.
relative dating
 

104. 
What theory agrees with fossil records that show no intermediate forms for long periods of time?
a.
gradualism
c.
punctuated equilibria
b.
evolution
 

105. 
Which term refers to similar structures that related species have inherited from a common ancestor?
a.
DNA sequences
c.
homologous structures
b.
developmental organisms
 

106. 
If two organisms look very similar during their early stages, this is evidence that the organisms
a.
have exactly the same DNA.
c.
evolved from a common ancestor.
b.
evolved from different ancestors.
 

107. 
A branching tree is
a.
a diagram showing how scientists think different groups of organisms are related.
b.
a species of tree that is not closely related to other tree species.
c.
a drawing that shows where different animals live in a tree.
 

108. 
Scientists combine evidence from fossils, body structures, early development, and DNA and protein structures to
a.
determine what bones an animal has in its forelimbs.
b.
determine the evolutionary relationships among species.
c.
decide which fossils are older than others.
 

109. 
What did Darwin observe about finches in the Galapagos Islands?
a.
Their feathers were adapted to match their environment.
b.
Their beaks were adapted to the foods they ate.
c.
They had identical phenotypes in all locations.
 

110. 
The gradual change in a species over time is called
a.
mutation.
c.
migration.
b.
evolution.
 

111. 
A trait that helps an organism survive and reproduce is called a(n)
a.
mutation.
c.
adaptation.
b.
selection.
 

112. 
Which term refers to the process by which individuals that are better adapted to their environment are more likely to survive and reproduce?
a.
natural selection
c.
competition
b.
overproduction
 

113. 
What theory proposes that species evolve during short periods of rapid change?
a.
absolute dating
c.
punctuated equilibria
b.
evolution
 

114. 
Which term refers to a species creating more offspring than can possibly survive?
a.
natural selection
c.
evolution
b.
overproduction
 

115. 
What evidence suggests that the ancestors of whales once walked on land?
a.
Scientists have found fossils of whale-like creatures that walked on land.
b.
Whales perform walking motions as they swim.
c.
Whales have similar DNA to elephants.
d.
Whales breathe through lungs.
 

116. 
How does natural selection lead to evolution?
a.
Stronger offspring kill weaker members of the species.
b.
Helpful traits accumulate among surviving members of the species.
c.
Overproduction provides food for stronger members of the species.
 

117. 
How do remains become petrified fossils?
a.
A sedimentary rock becomes a cast.
b.
Molds and casts fill with sediment.
c.
Minerals replace all or part of an organism.
 

118. 
Why do scientists think related species have similar body structures and development patterns?
a.
The species inherited many of the same genes from a common ancestor.
b.
The species inherited many of the same genes from each other.
c.
The species inherited all of the same genes from a common ancestor.
 

119. 
Entire insects have been perfectly preserved in
a.
amber formed from the hardened sap of evergreen trees.
b.
tar pits that were once covered with water.
c.
casts formed when molds filled with hardened minerals.
 

120. 
If the half-life of a radioactive element is 4 days, how long will it take for three fourths of a sample of the element to decay?
a.
2 days
c.
8 days
b.
4 days
 

Completion
Complete each sentence or statement.
Use the list given to you to fill in the answers. Each word is used once.
 

121. 
Mendel used ____________________-pollination to produce purebred plants.
 

 

122. 
In pea plants, the tall-stem allele and the short-stem allele are different forms of the same ____________________.
 

 

123. 
Mendel used the principles of ____________________ to predict what percent of offspring would show a particular trait.
 

 

124. 
An organism that has two dominant or two recessive alleles is said to be ____________________ for that trait.
 

 

125. 
Genes are located on structures called ____________________.
 

 

126. 
The process in which a parent cell divides twice to produce sex cells is called ____________________.
 

 

127. 
If all of the sex cells of an organism have the T allele, the genotype of that organism must be ____________________.
 

 

128. 
Sets of three bases code for the production of ____________________ that make up proteins.
 

 

129. 
The substitution of one base for another during DNA replication is an example of a(n) ____________________.
 

 

130. 
A mutation that has no effect on an organism is said to be ____________________.
 

 

131. 
The three alleles on the single gene that controls blood type are said to be ____________________ alleles.
 

 

132. 
A person’s surroundings, or ____________________, can change the effects of a person’s genes.
 

 

133. 
An egg that is fertilized by a sperm cell with a(n) ____________________ chromosome will develop into a female.
 

 

134. 
A recessive allele can be passed to offspring by a(n) ____________________ who does not show the trait.
 

 

135. 
People who have the genetic disorder called ____________________ disease suffer from lack of oxygen in the blood.
 

 

136. 
A person who has the genetic disorder called ____________________ bleeds easily.
 

 

137. 
Down’s syndrome is caused by the presence of an extra ____________________.
 

 

138. 
A doctor performs a procedure called ____________________ to get cells from the fluid that surrounds a developing baby.
 

 

139. 
A karyotype can be used to diagnose the genetic disorder called ____________________.
 

 

140. 
Breeders use a technique called ____________________ to cross genetically different individuals.
 

 

141. 
A gene from one organism is inserted into the DNA of another organism in the process known as ____________________.
 

 

142. 
Scientists in the Human Genome Project are working to identify the ____________________ sequence of every human gene.
 

 

143. 
A selective breeding technique called ____________________ is used to breed purebred dogs.
 

 

144. 
A gene is said to have multiple alleles if it has more than ____________________ alleles.
 

 

145. 
The only traits that can be acted upon by natural selection are those that are controlled by ____________________.
 

 

146. 
The separation of a group of organisms from the rest of its species by a mountain range is an example of ____________________ isolation.
 

 

147. 
Most fossils are found in ____________________ rock.
 

 

148. 
The theory of ____________________ states that species evolve quickly over a short time.
 

 

149. 
Living things first appeared during the geologic time period known as ____________________.
 

 

150. 
Scientists show how groups of organisms are related by placing them on a diagram called a(n) ____________________.
 

 



 
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