Study Island
Copyright © 2014 Edmentum - All rights reserved.
Generation Date: 09/04/2014
Generated By: Kurt Ritter
DNA & Genetics
1. Cells store genetic information in DNA. That genetic information is used to
synthesize _______.
A. proteins
B. genes
C. polysaccharides
D. carbohydrates
DNA & Genetics
2. In eukaryotic organisms, DNA transcription occurs in the _______ of a cell.
A. mitochondria
B. nucleus
C. ribosome
D. cytoplasm
Biotechnology
3. Malaria is a disease caused by parasites that reproduce within red blood cells. Malaria can
cause fever, chills, nausea, flu-like symptoms, and in some cases, coma and death. This disease
is prevalent in warm climates, especially South America, Africa, and the southern portions of
Asia.
Sickle-cell anemia is a genetic disorder that causes red blood cells to change shape when they are
deoxygenated. The resultant sickle-shaped blood cells can get stuck in blood vessels and cause
damage and pain. This disease is also prevalent in South America, Africa, and Asia.
Lately, it was discovered that people who carry the sickle-cell trait heterozygously are resistant
to malaria. How could biotechnology best use this infomation to help people living in these
areas?
A.
Biotechnology could be used to insert the malaria resistant genes without causing sickle
cell anemia.
B. Biotechnology could be used to eliminate all sickle-cell genes.
Biotechnology could be used to make the climate cooler so that mosquitoes are unable to
C.
breed.
D. Biotechnology could be used to alter the mosquito DNA.
Biotechnology
4. Biotechnology is used in a variety of areas from agriculture to pharmaceuticals to fuels.
How is the use of biotechnology in agriculture beneficial to the environment?
A.
B.
C.
D.
Genetically altered crops require less pesticide.
Genetically altered crops are more delicious.
Genetically altered crops produce less carbon dioxide.
Genetically altered crops are unable to reproduce.
Heredity
5. Which hereditary rule explains why a self-fertilizing parent that is heterozygous for the A
locus (Aa) can produce offspring that are AA or aa?
A. codominance
B. principle of independent assortment
C. principle of segregation
D. dominance
Heredity
6. Punnett squares depict the genotypes of two parents and are used to predict the inherited traits
of offspring. Which of the following would be the missing predicted trait in the table below?
A. OA
B. OO
C. AA
D. AO
Mutations & Genetic Variability
7. The chart below shows the codons that make up the genetic code and the sequence of
nucleotides that corresponds to them.
A mistake during DNA replication leads to a mutation in the nucleotide sequence shown below.
What kind of mutation will result from the mistake made during DNA replication in the
nucleotide sequence above?
A. a nonsense mutation
B. a silent mutation
C. a chromosomal mutation
D. a frame shift mutation
Biotechnology
8. Until recently, looking through detailed records on family history of disease was the only way
to try to avoid certain genetic conditions in some purebred dogs, such as a bleeding disorder
called von Willebrand's Disease. What technological advances may have reduced the need for
this process?
A. use of reproductive sperm donation to increase fertility
B. determination of the sequence of the human genome
C. none of these
D. development of canine testing for genetic disease carriers
Heredity
9. Sarah is doing an experiment on pea plants. She is studying the color of the pea plants. Sarah
has noticed that many pea plants have purple flowers and many have white flowers.
Sarah crosses a homozygous white flower and a homozygous purple flower. The cross results in
all purple flowers.
What is true of the color of pea plants?
A. White flowers and purple flowers are codominant.
B. Purple flowers and white flowers are recessive to red.
C. Purple flowers are dominant to white flowers.
D. White flowers are dominant to purple flowers.
Heredity
10. A cross between two squash plants that produce yellow squash results in 124 offspring: 93
produce yellow squash and 31 produce green squash. What are the likely genotypes of the plants
that were crossed?
A. one YY, one Yy
B. both YY
C. both Yy
D. both yy
Biotechnology
11. The first commercial application of genetic engineering was the use of bacteria to make
insulin, a medicine needed by diabetics. Before the use of genetically-engineered bacteria,
insulin had to be harvested from the pancreases of slaughtered animals.
How has genetic engineering most likely improved the lives of diabetics?
A.
B.
C.
D.
It has made the demand for insulin decrease.
It has made it easier for diabetics to inject themselves with insulin.
It has made insulin cheaper and more readily available.
It has made the incidence of diabetes decrease.
Mutations & Genetic Variability
12. A genetic mutation that causes a codon that should code for a specific amino acid to be
changed into a stop codon results in a shortened protein product and is known as
A. a nonsense mutation.
B. a frame shift mutation.
C. a silent mutation.
D. a chromosomal mutation.
DNA & Genetics
13. During a stage of protein synthesis, codons in mRNA molecules are used to specify the
sequence of amino acids in polypeptide chains. What is this process called?
A. codification
B. gene expression
C. translation
D. transcription
Heredity
14. AB blood type is an example of __________.
A. independent assortment
B. polygenic inheritance
C. incomplete dominance
D. codominance
Biotechnology
15. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
16. Most heritable differences are due to
A. point mutations that occur during mitosis.
B. gene shuffling that occurs during the production of gametes.
C. the insertion of incorrect sequences of DNA by faulty polymerases.
D. the inability to form proper DNA sequences due to poor nutrition.
DNA & Genetics
17. After the process of _______ occurs, each daughter cell receives an exact copy of the parent
cell's DNA.
A. DNA translation
B. DNA replication
C. DNA transcription
D. DNA elongation
DNA & Genetics
18. What is a major difference between DNA replication and DNA transcription?
A.
RNA molecules produced by transcription are much shorter in length than DNA molecules
produced by replication.
B.
DNA replication takes place in the nucleus, while DNA transcription takes place in the
cytoplasm.
C.
DNA replication involves the nitrogenous base uracil, while DNA transcription involves
the nitrogenous base thymine.
D.
DNA transcription only occurs in multicellular organisms, while DNA replication occurs
in all organisms.
DNA & Genetics
19. A parent DNA molecule replicates, resulting in two daughter DNA molecules. Which of the
following is true?
A. Each daughter molecule contains two DNA strands from the parent molecule.
B. Each daughter molecule contains two new strands of DNA.
C. Each daughter molecule contains one DNA strand from the parent molecule.
D. Each daughter molecule contains four total strands of DNA.
Biotechnology
20. Scientists have taken genes from a species of bacteria that is pathogenic to several insects
and inserted the genes into potato plants. The bacterial genes cause a cell to produce toxins that
kill the insects. As the potato plants grow, every cell of the plant contains the toxin-producing
genes. This makes the potato resistant to attack by crop pests.
Which of the following is a limitation of this new technology?
The introduced gene will cause more diversity in the potato's genome, thus causing the
A. potato plant to become extinct.
The genetically altered potato plants will kill off so many insects that companies that
B. manufacture pesticides will soon go out of business.
C.
D.
Over time, insects are likely to develop resistance to the bacterial toxin.
There are no foreseen limitations with inserting bacterial genes into crop plants.
Heredity
21. What is the term used to describe the heritable, physical characteristics of a living organism?
A. genotype
B. allele
C. phenotype
D. pedigree
Biotechnology
22. Many crops such as tomatoes and corn are now routinely genetically manipulated to become
more resistant to disease and herbicides. What is one disadvantage of this genetic resistance?
A. The crops always become less flavorful and less nutritious.
B. The crops are no longer able to reproduce.
C. The genes may be transferred to weeds during pollination.
D. The genes are transferred to their own progeny when they reproduce.
Mutations & Genetic Variability
23. How could an apple farmer increase the number of genotypes and phenotypes present in his
next apple crop?
A. It would be impossible for a farmer to increase the genetic variation of plants.
B. Cross plants that have very different characteristics.
C. Cross plants that have the same characteristics.
D. Make genetic clones of plants using asexual reproduction.
Heredity
24. According to Mendel's Law of Segregation, meiosis involves the separation of a parent
organism's alleles in order to form gametes. Since the alleles separate into different gametes,
only one allele passes from each parent on to an offspring. This segregation of alleles during
meiosis
A.
B.
C.
D.
decreases the genetic variability of the offspring.
decreases the chance that an offspring will receive a dominant allele.
increases the chance that an offspring will receive a dominant allele.
increases the genetic variability of the offspring.
DNA & Genetics
25. How is the nucleus involved in the production of enzymes?
The nucleus transcribes and releases messenger RNA signaling for the enzymes to be
A. synthesized.
B.
C.
The nucleus is involved in the packaging and transportation of enzymes outside of the cell.
The nucleus receives the messenger RNA and is the site where enzymes are synthesized.
The nucleus translates the ribosomal RNA for the enzymes to be synthesized in
D. mitochondria.
DNA & Genetics
26. Which of the following correctly organizes genetic material from the broadest category to the
most specific category?
A.
B.
C.
D.
genome
DNA molecule
genome
chromosome
gene
genome
chromosome
chromosome
chromosome
gene
gene
DNA molecule
DNA molecule
DNA molecule
genome
gene
Mutations & Genetic Variability
27. During meiosis, the process of crossing over results in new combinations of alleles due to the
fact that
A. genetic material is exchanged between chromosomes during this process.
B. genetic material is added by a third chromosome during this process.
C. genetic material is removed during this process.
D. genetic material always mutates randomly during this process.
Mutations & Genetic Variability
28. The chart below shows the codons that make up the genetic code and the sequence of
nucleotides that corresponds to them.
A mistake during DNA replication leads to a mutation in the nucleotide sequence shown below.
This mutation results from the insertion of two nucleotides into the original sequence, which
causes the reading frame of the sequence to change. This kind of mutation is known as
A. a chromosomal mutation.
B. a frame shift mutation.
C. a silent mutation.
D. a nonsense mutation.
Mutations & Genetic Variability
29. A frame shift mutation is a genetic mutation that is caused by the insertion or deletion of a
specific number of nucleotides that shifts the reading frame of the sequence.
The insertion or deletion of how many nucleotides would cause a frame shift mutation?
A. 6
B. 9
C. 3
D. 2
DNA & Genetics
30.
Which of the following is true regarding the process shown above?
The process shown above is known as transcription and involves the production of proteins
A. from DNA.
The process shown above is known as translation and involves the production of proteins
B. from RNA.
The process shown above is known as replication and involves the production of DNA
C. from RNA.
The process shown above is known as cloning and involves the production of RNA from
D. protein molecules.
Biotechnology
31. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
32. Technology Enhanced Questions are not available in Word format.
Heredity
33. Trey goes to a rabbit farm to look at a litter of newborn rabbits. The newborns are all
different colors. They are gray, black, white, light brown, and dark brown.
What type of inheritance pattern are these rabbits likely displaying?
A. incomplete dominance
B. dominant-recessive
C. multiple alleles
D. codominance
Heredity
34. Lisa breeds snakes. She bred a solid brown male python with a tan female python whose
body was covered with a black diamond pattern. Upon hatching, all of the baby pythons were
brown with a faint diamond pattern.
Which of the following inheritance patterns most likely determined the color of Lisa's baby
pythons?
A. incomplete dominance
B. sex-linked
C. codominance
D. autosomal dominant-recessive
DNA & Genetics
35. The picture below shows the process of transcription.
During transcription, enzymes bind to a molecule of DNA.
Then, the enzymes unwind and separate the DNA's double helical strands. As the molecule
unwinds, complementary nucleotides pair with one of the DNA strands to form
A. a protein molecule.
B. an identical strand of DNA.
C. an RNA molecule.
D. a DNA polymerase.
DNA & Genetics
36. DNA replication results in two identical DNA molecules. What role do DNA helicases have
in DNA replication?
A. DNA helicases break the hydrogen bonds in the DNA molecule.
B. DNA helicases check the new DNA molecule for errors.
DNA helicases hold the two strands of the old DNA apart and prevent them from
C.
reuniting.
D. DNA helicases add nucleotides to the exposed nitrogen bases of the old DNA.
Mutations & Genetic Variability
37. Triple X syndrome, or trisomy X, occurs when a female has an extra X chromosome in each
of her cells. This results when the mother's reproductive cells divide improperly, and two X
chromosome are moved into one gamete. When that gamete is fertilized and the father's DNA
and X chromosome are combined with the mother's, that gives the cell three X chromosomes
instead of two.
Triple X syndrome occurs because of _______.
A. point mutations
B. nondisjunction
C. crossing over
D. deletions
Mutations & Genetic Variability
38. During normal meiosis, homologous chromosomes pair up and separate so that each gamete
receives a copy of every chromosome.
Sometimes an error is made during this separation and homologous chromosomes fail to
separate. This results in one gamete that has two copies of the chromosome, and another gamete
that does not have the chromosome at all.
This type of error is known as _______ and usually results in zygotes that either do not develop
to term or have severe abnormalities.
A. chromosome translocation
B. chromosome insertion
C. chromosome nondisjunction
D. chromosome inversion
DNA & Genetics
39. What is a gene?
A. a characteristic of any organism
B. any single amino acid in a multicellular organism
C. a set of instructions in the DNA sequence of an organism
D. a sex cell that aids in organism reproduction
DNA & Genetics
40. How are complementary strands of DNA held together?
A. with phosphodiester bonds connecting sugars and phosphate groups
B. with hydrogen bonds connecting complementary sugars
C. with hydrogen bonds connecting complementary bases
D. with ionic bonds between sugars and phosphate groups
Biotechnology
41. In the 1970s, many biotechnologists worked to develop a biodiesel that was an alternative to
petroleum diesel. The results of their research was a biodiesel fuel that can be burned by most
regular diesel engines and releases up to 50% less carbon emissions than petroleum diesel.
If the majority of diesel-burning vehicles in the United States begin using biodiesel, what would
be the most likely environmental impact?
A.
B.
C.
D.
The amount of polluted runoff flowing into the ocean will decrease.
There will be no environmental impact.
Air quality across the country will improve.
The amount of acid rain falling on the country will increase.
Heredity
42. An organism's genotype can best be defined as its
A. number of chromosomal pairs.
B. number of recessive genes.
C. inherited physical appearance.
D. inherited combination of alleles.
Biotechnology
43. Many genetic disorders have mild, moderate, and severe disease forms that are identified by
speed of symptom progression. As disease features may worsen over several years, the severity
of the disease cannot always be determined in childhood.
Which of the following technological advances would help doctors determine whether an
individual has the most severe form of a disease in childhood?
A. the discovery of a specific gene mutation associated with the severe disease form
B. the discovery of a new biochemical test that identifies presence of the disease
C. the discovery of a similar genetic disease that occurs in a mild disease form
D. the discovery of a specific gene mutation associated with the mild disease form
DNA & Genetics
44. Which of the following molecules is the subunit of DNA that links together to form strands
of DNA?
A. a polymerase
B. a nucleotide
C. a phosphate base
D. a codon
DNA & Genetics
45. Which of the following is the term for one possible form of the gene for a particular trait?
A. sex-linked trait
B. codon
C. autosomal trait
D. allele
Heredity
46. Fifty percent of the offspring produced by a cross between pea plants have seeds with a
wrinkled (r) appearance caused by the presence of a homozygous recessive gene. What were the
genotypes of the parents?
A. RR × Rr
B. Rr × Rr
C. RR × rr
D. Rr × rr
Heredity
47.
A recessive gene located on the X chromosome is the cause of muscular dystrophy in affected
individuals. Males are more likely to suffer from muscular dystrophy than females because
A. muscular dystrophy is associated with high testosterone levels.
B. females have no copies of the X chromosome.
C. males have two copies of the X chromosome.
D. males have only one copy of the X chromosome.
Biotechnology
48. Genetic engineering is the process of manipulating genes for practical purposes. Today,
scientists have genetically engineered many types of organisms including crop plants.
Which of the following is a current benefit gained from genetically engineered crops?
A.
B.
C.
D.
Some genes can be transferred to wild plants in the area.
Some animals develop allergies to the genetically engineered crops.
Some food staples, such as rice, contain more nutrients.
Some disease resistant fruits and vegetables are less flavorful.
Mutations & Genetic Variability
49. What is occurring in the diagram below?
A. Alleles are independently assorting.
B. Segments of DNA are crossing over.
C. Genes are replicating.
D. Sister chromatids are separating.
Heredity
50. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
51. Gametes in humans are haploid. This means that they have half the number of chromosomes
as normal body cells. Sometimes, the gamete of a male and the gamete of a female combine to
form a zygote that will eventually turn into a fetus.
Phenotypic changes in a fetus may result
A. if a mutation occurs in the gametes.
B. if a mutation occurs in the father's heart cells.
C. if a mutation occurs in the mother's brain cells.
D. only if a mutation occurs in both the mother's and father's cells.
Biotechnology
52. In the early to mid-1980's, police began using DNA evidence to convict criminals of violent
crimes. Currently, techniques such as DNA fingerprinting are frequently used in criminal
investigations, and some countries, such as England, even keep DNA databases so that persons
who commit crimes may be more quickly apprehended.
To what branch of science do these techniques belong?
A. biotechnology
B. quantum physics
C. comparative anatomy
D. inorganic chemistry
DNA & Genetics
53. When a molecule of double-stranded DNA undergoes replication, it results in
A. three double-stranded DNA molecules, each composed of sections of old and new strands.
B. four double-stranded DNA molecules, each composed only of old strands of DNA.
C. two double-stranded DNA molecules, each composed of one new and one old strand.
D. one double-stranded DNA molecule composed only of entirely new strands.
Biotechnology
54. Every year millions of crops are lost due to pests. In recent times, however, scientists have
learned that they can insert a gene into the DNA of specific crops that gives them a higher pestresistance than normal. This technology allows farmers to have higher crop yields and increases
the supply of valuable food sources.
This technology is an example of
A. DNA transcription.
B. gene splicing.
C. binary fission.
D. crossing over.
Heredity
55. In pea plants, tall (T) plants are dominant over short (t) plants. If a heterozygous (Tt) pea
plant is crossed with a homozygous dominant (TT) pea plant, all of the resulting pea plants
should be tall (TT or Tt). Each plant will receive a dominant allele from the homozygous
dominant plant, while they could receive either a dominant or recessive allele from the
heterozygous plant.
The fact that each plant gets only one allele from each parent plant is detailed in the Law
of _______.
A. Multiple Alleles
B. Genetic Inheritance
C. Independent Assortment
D. Segregation
DNA & Genetics
56. Proteins play a variety of roles within cells, but there are many steps that must be undertaken
to make these proteins and deliver them to where they need to go.
The above picture implies that
no organelles are necessary for the synthesis and transportation of proteins.
A.
B.
C.
D.
organelles must interact with each other to synthesize and transport proteins.
only the organelles shown in the picture are important to cells.
organelles act independently when synthesizing and transporting proteins.
Heredity
57. Lupe grows pea plants in her garden. The pea plants have flowers that can be either purple or
white, with purple color being dominant to white color. The peas produced by Lupe's pea plants
can also be either round or wrinkled, with round peas being dominant to wrinkled peas.
Lupe crosses two pea plants that are heterozygous for both traits. If a gamete from this cross
receives a dominant allele for flower color, how does this influence the probability of the gamete
receiving a dominant allele for pea shape?
(Assume that the genes for flower color and pea shape follow the law of independent
assortment.)
A.
B.
C.
It causes the gamete to be unable to receive a dominant allele for pea shape.
It has no effect on the probability of the gamete receiving a dominant allele for pea shape.
It increases the probability that the gamete will receive a dominant allele for pea shape.
D.
It decreases the probability that the gamete will receive a dominant allele for pea shape.
Heredity
58. Guinea pig coat color is determined by a single gene. The allele for black coat color is
dominant to brown. In a cross between two black-haired guinea pigs, 20 offspring are born. If
both parents were heterozygous, probability would predict that approximately how many of the
20 offspring would have brown hair?
A. 10
B. 15
C. 5
D. 0
Mutations & Genetic Variability
59. Errors that are made during DNA replication may result in
A. identical twins.
B. a viral infection.
C. mutations.
D. radioactive decay.
Mutations & Genetic Variability
60. An organism's genotype describes its specific combination of alleles. For example, an Aa
genotype is heterozygous for the A allele.
An organism's phenotype describes a visible trait, such as tall height, brown eyes, or black fur.
How does genotypic variation occur?
A.
B.
C.
Genotypic variation occurs when alleles are randomly sorted during sexual reproduction.
Genotypic variation only occurs during binary fission.
Genotypic variation occurs when alleles are randomly sorted during asexual reproduction.
D.
Genotypic variation only occurs when genetic mutations occur.
Heredity
61. Human height is a polygenic trait. This means that the
A. trait is completely controlled by only one pair of genes.
B. trait is controlled by the genes inherited from the father only.
C. trait is controlled by more than one pair of genes.
D. trait is controlled by the genes inherited from the mother only.
Mutations & Genetic Variability
62. Sometimes, during the process of replication, the DNA code is copied incorrectly, and an
incorrect nucleotide is attached to the new strand of DNA.
This incorrect copy is known as a
A. codon.
B. mutation.
C. duplicate.
D. protein.
Biotechnology
63. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
64. The diagram below illustrates a process that can occur during cell division and results in an
alteration in the composition of a chromosome. Each letter in the diagram represents a specific
gene on the chromosome.
The diagram shows that a section of the chromosome was broken out and reinserted backwards.
This is known as
A. chromosome inversion.
B. chromosome insertion.
C. chromosome translocation.
D. chromosome deletion.
Heredity
65. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
66. During meiosis, homologous chromosomes frequently exchange portions of their DNA. This
process further increases the number of different genotypes that can appear in an offspring. What
is the name of this process?
A. crossing-over
B. mutation
C. genetic transfer
D. transduction
Heredity
67. Carla receives an allele for blue eyes from her mother, and an allele for brown eyes from her
father.
If brown eye color is a dominant trait and blue eye color is a recessive trait, what can be
determined about the color of Carla's eyes?
A. Carla has brown eyes.
B. Carla has blue eyes.
C. Carla has green eyes.
D. Carla's eye color can not be determined.
Heredity
68. Technology Enhanced Questions are not available in Word format.
Mutations & Genetic Variability
Types of Chromosome Disorders
Disease
Characteristics
Cause
Cri-du-chat
Syndrome
(Cry of the Cat)





improperly developed larynx
babies cry like distressed cats
severe mental retardation
small round faces
small cranium
deletion of parts of
chromosome 5
Edward's
Syndrome
(Trisomy 18)





extra chromosome 18

severe mental retardation
elongated skull
very narrow pelvis
feet with round bottoms
two central fingers grasped by
thumb and little finger
death in early infancy







mild to severe retardation
short height
broad hands
stubby fingers and toes
round face
large protruding tongue
speech difficulties
extra chromosome 21
Down Syndrome
(14-21
Translocation)

same as Trisomy 21
extra chromosome 21 attached
to chromosome 14
Turner's
Syndrome
(XO)


female appearance
infertility
lack of a second sex
chromosome
Klinefelter's
Syndrome
(XXY)


female characteristics
infertility
extra X chromosome
Down Syndome
(Trisomy 21)
69.
A cat's coloring is mostly determined by genes on their X chromosomes, which contain alleles
for colors, such as black, orange, gray, and cream. The allele for white fur is located on a
different gene.
Calico cats, by definition, must display three different colors in their fur - white plus two of the
other colors. This is easily possible in female cats, because females normally possess two X
chromosomes. However, this occurs rarely in male cats, because males typically possess only
one X chromosome plus one Y chromosome.
What must be the genetic make-up of a male calico cat, and what type of chromosome disorder
does this most resemble?
A. XO, Turner's syndrome
B. XYY, Cri-du-chat syndrome
C. XXY, Klinefelter's syndrome
D. XX, Down's syndrome
Mutations & Genetic Variability
70. ______ is a source of genetic variation that involves the swapping of sections of
chromosomes during meiosis.
A. Crossing over
B. Fertilization
C. Transcription
D. Translation
Biotechnology
71. In the 1920's, a woman by the name of Anna Anderson claimed to be the Grand Duchess
Anastasia, the youngest daughter of Tsar Nicholas II. However, DNA testing confirmed that she
was not who she claimed to be. Which of the following uses of biotechnology does this example
best demonstrate?
A. Biotechnology allows for the improved varieties of plants, animals, and medicines.
B. Biotechnology allows for criminals to be captured through forensic testing.
C. Biotechnology allows for determining the degree of relatedness among individuals.
D. Biotechnology allows for the screening and possible treatment of genetic disorders.
Biotechnology
72. In 1990, scientists at the National Institutes of Health used gene therapy to try to treat a 4year-old girl suffering from severe combined immunodeficiency disease (SCID). This genetic
disease made her extremely susceptible to infections. The scientists used a virus to inject normal
genes into the girl's immune system cells. The experiment was moderately successful, and the
girl's health improved but only for short periods of time.
If this form of gene therapy could be fine-tuned, how would it impact society?
A. The number of infections from genetically-engineered viruses would increase.
B. Most Americans would no longer suffer from heart disease.
C. People would need to be genetically tested before having children together.
D. Many genetic diseases would be curable.
DNA & Genetics
73. A diagram demonstrating the process of protein translation is shown below.
The structure labeled with a question mark in the diagram represents
A. a ribosome.
B. a mitochondrion.
C. a vacuole.
D. a chloroplast.
DNA & Genetics
74. The DNA sequences that make up the genetic code of an organism determine which traits the
organism will exhibit.
How are the instructions coded by DNA translated into an organism's physical traits?
A. DNA sequences that code for genetic instructions attach to phosphate groups that express
an organism's physical traits.
Instructions coded by DNA sequences are translated into proteins which express an
B. organism's physical traits.
DNA sequences both code genetic instructions within an organism and express an
C. organism's physical traits.
Instructions coded by DNA sequences are translated into nucleotides which express an
D. organism's physical traits.
DNA & Genetics
75. The nucleotide of DNA is one large molecule composed of three smaller molecules. Which
of the following sets of molecules bond together to form a nucleotide?
A. deoxyribose, a nitrogen base, a phosphate group
B. a nitrogen atom, a phosphate atom, and a five-carbon sugar
C. adenine, thymine, and cytosine
D. a purine, a pyrimidine, and a five-carbon sugar
DNA & Genetics
76. All cells contain DNA, which provides information for the cells to make
A. different kinds of proteins.
B. new types of genes.
C. different kinds of DNA.
D. new types of organisms.
Heredity
77. One possible form of a gene that codes for a particular trait is known as _______.
A. a chromosome
B. a genotype
C. a phenotype
D. an allele
DNA & Genetics
78.
During the process shown above, the two strands of one DNA molecule are unwound. Then,
DNA polymerases add complementary nucleotides to each strand which results in the formation
of two identical DNA molecules.
This process is known as DNA _______.
A. transcription
B. translation
C. replication
D. cloning
Biotechnology
79. Which of the following is an example of gene splicing?
A.
B.
C.
D.
two human chromosomes pair up during meiosis and exchange parts of their DNA
a genetically identical copy of an entire organism is produced through cloning
a mutation that occurs during meiosis results in a chromosomal abnormality
a segment of human DNA is inserted into the DNA sequence of a bacterium
Mutations & Genetic Variability
80. Which of the following is true about DNA mutations?
A.
B.
C.
Mutations can only be caused by environmental factors such as radiation.
Mutations can only occur in the sex cells of an organism.
Mutations can spontaneously occur during DNA replication.
D.
Mutations can only occur in the body cells of an organism.
Mutations & Genetic Variability
81. When environmental conditions change, it is more likely that at least some members of a
species will survive if
A. there is variation among the members.
B. the species requires very specific environmental conditions.
C. the members are genetically identical.
D. the species reproduces asexually.
Biotechnology
82. Scientists have genetically-engineered some strains of bacteria to consume toxins, such as
oil, and to excrete the toxins as harmless substances.
How might these bacteria most likely impact society?
A.
B.
C.
D.
They will cause people to become more careless about polluting the environment.
They will cause more bacterial infections in people.
They will enable people to easily clean up spilled pollutants in the environment.
They will grow out of control and consume the world's oil supply.
Heredity
83. Mrs. Smith has blood type A. Her father has blood type A, and her mother has blood type B.
If Mr. Smith has blood type AB, what is the probability that they will have a child with blood
type AB?
A. 25%
B. 0%
C. 100%
D. 50%
DNA & Genetics
84. Integral membrane proteins, such as transport proteins, are permanently attached to cellular
membranes. After integral membrane proteins are synthesized, which organelle would aid in
transporting them to their final destination?
A. endoplasmic reticulum
B. mitochondrion
C. plasma membrane
D. chloroplast
Heredity
85. A certain type of flower has two alleles for color (blue, purple), and two alleles for stem
height (tall, short). A tall blue flower and a short purple flower are crossed, resulting in tall blue
flowers, short blue flowers, tall purple flowers, and short purple flowers.
What law does this example help to prove?
A. Law of Genetic Inheritance
B. Law of Independent Assortment
C. Law of Multiple Alleles
D. Law of Segregation
DNA & Genetics
86. How does DNA help with the transfer of genetic material from parents to offspring?
A.
B.
Genes in DNA code for the production of proteins, which cause traits to be expressed.
Proteins bind to DNA, which activates them and forces them to express certain traits.
DNA is mutated by a chemical passed from parents to offspring to form proteins that
C. express traits.
Enzymes break down DNA, releasing amino acids that join to form proteins and express
D. various traits.
Heredity
87. A(n) _______ is a characteristic arising from genes located on chromosomes that are not
gender-determining.
A. allele
B. autosomal trait
C. sex-linked trait
D. genotype
Heredity
88. A student crosses two true-breeding pea plants, one with green pods and the other with
yellow pods. If yellow is dominant over green, what phenotypic results will the student find in
the F1 generation?
A. 100% yellow
B. 100% green
C. 75% green, 25% yellow
D. 75% yellow, 25% green
Biotechnology
89. Recently, scientists have genetically engineered fruit crops to contain vaccines. How might
these fruit crops most likely benefit society?
A.
B.
C.
D.
They could encourage people to eat healthier food.
They could make fruit crops more productive than they were before.
They could help eradicate all infectious diseases in the world.
They could make it cheaper and easier to administer vaccines.
Biotechnology
90. A vaccine is a substance that contains all or part of a noninfectious version of a diseasecausing organism. When the vaccine is administered to a person, the person's immune system
attacks the noninfectious version of the organism and learns to recognize its surface proteins.
The next time the immune system comes in contact with the same surface proteins, it has a
defense already prepared in order to respond quickly to the invading organism. In this way, a
vaccine gives people immunity to the disease-causing organism.
Vaccines can be life-saving, but there have been a few cases of people catching a disease from
the administered vaccine.
How might genetically engineered organisms solve this problem?
Harmless organisms could be genetically engineered to recognize and destroy random cells
A. in the body.
B.
Disease-causing organisms could be genetically engineered to only be harmful to plants.
Disease-causing organisms could be genetically engineered to produce insulin instead of
C. toxins.
Harmless organisms could be genetically engineered to have surface proteins from diseaseD. causing organisms.
Biotechnology
91. The diagram above shows the process of recombinant DNA technology.
According to this diagram, segments of DNA can be cut using ________.
A. enzymes
B. plasmids
C. bacterial cells
D. vectors
Mutations & Genetic Variability
92. The chart below shows the codons that make up the genetic code and the sequence of
nucleotides that corresponds to them.
A mistake during DNA replication leads to a mutation in the nucleotide sequence shown below.
What kind of mutation will result from the mistake made during DNA replication in the
nucleotide sequence above?
A. nonsense mutation
B. chromosomal mutation
C. silent mutation
D. frame shift mutation
Mutations & Genetic Variability
93. Which of the following is a source of genetic variation in sexually-reproducing organisms?
A. meiosis
B. translation
C. mitosis
D. all of these
Biotechnology
94. Advances in biotechnology, especially regarding genetic testing and gene therapy, now allow
for the screening and possible treatment of many genetic disorders. During gene therapy, for
example, specific gene sequences are inserted into an individual's cells and tissues to replace a
defective or mutant allele.
What have scientists found to be the most efficient and effective way to insert new sequences
into an individual?
A.
B.
C.
D.
Scientists inject DNA strands into cells using a syringe.
Scientists have created genetically altered foods that release DNA during digestion.
Scientists use viruses to insert specific gene sequences.
Scientists irradiate genes so that they can be absorbed through the skin.
Biotechnology
95. Genetic engineering, gene splicing, and recombinant DNA technology are all techniques
used in biotechnology. Before using these technologies, however, what is required?
A.
B.
C.
D.
a doctorate degree in biotechnology or molecular biology
specific scientific knowledge about the natural system being modified
a patent for the technology in question
approval of their usage by popular vote
DNA & Genetics
96. DNA contains instructions for making the different molecules, such as proteins, that the cell
needs for growth and function. To use these instructions, the DNA must first be _______
into _______.
A. transcribed, mRNA
B. translated; mRNA
C. transcribed; amino acids
D. translated; amino acids
Biotechnology
97. Some types of crops have been genetically-engineered to resist certain types of diseases and
pests. How might these genetically-engineered crops impact the environment?
A.
B.
C.
D.
They will harm the environment by promoting slash and burn agriculture.
They will help the environment by allowing farmers to use fewer pesticides.
They will help the environment by causing pest species to become extinct.
They will harm the environment by introducing synthetic genes into other plants.
Biotechnology
98. Today, genetically-engineered crops are becoming more common. Which of the following is
a likely possible negative impact of the use of genetically-engineered crops?
A.
B.
Human DNA might experience recombinant mutations with the plant DNA.
Animals that consume genetically-engineered crops will no longer be able to reproduce.
Crops that have been genetically engineered to resist disease would increase the use of
C. pesticides.
D.
Genetically-engineered genes can be transferred to wild plants in the area.
Mutations & Genetic Variability
99. A genetic mutation that does not result in a change in the amino acid sequence of the
resulting protein is called
A. a silent mutation.
B. a frame shift mutation.
C. a chromosomal mutation.
D. a nonsense mutation.
Mutations & Genetic Variability
100. Down syndrome is a genetic disorder that is typically caused by an extra copy of
chromosome 21 in a person's genome. In a small number of cases, however, Down syndrome
occurs because a section of chromosome 21 becomes fused onto another chromosome.
The type of Down syndrome that occurs because a section of chromosome 21 attaches to another
chromosome is an example of a genetic disorder caused by
A. a recessive allele.
B. a frame shift mutation.
C. chromosome translocation.
D. chromosome deletion.
Answers
1. A
2. B
3. A
4. A
5. C
6. B
7. A
8. D
9. C
10. C
11. C
12. A
13. C
14. D
15. -16. B
17. B
18. A
19. C
20. C
21. C
22. C
23. B
24. D
25. A
26. D
27. A
28. B
29. D
30. B
31. -32. -33. C
34. A
35. C
36. A
37. B
38. C
39. C
40. C
41. C
42. D
43. A
44. B
45. D
46. D
47. D
48. C
49. B
50. -51. A
52. A
53. C
54. B
55. D
56. B
57. B
58. C
59. C
60. A
61. C
62. B
63. -64. A
65. -66. A
67. A
68. -69. C
70. A
71. C
72. D
73. A
74. B
75. A
76. A
77. D
78. C
79. D
80. C
81. A
82. C
83. A
84. A
85. B
86. A
87. B
88. A
89. D
90. D
91. A
92. C
93. A
94. C
95. B
96. A
97. B
98. D
99. A
100. C
Explanations
1. The genetic information stored in cells is used to synthesize proteins.
During protein synthesis, DNA is first replicated to form other copies of DNA. Then, it is
transcribed to form strands of RNA. Finally, the RNA is translated into proteins which help the
body to perform numerous functions.
2. In eukaryotic organisms, each cell's DNA is held in the nucleus. Since transcription involves
the copying of DNA, it takes place in the nucleus. The resulting mRNA strand then moves
from the nucleus to the cytosol where translation takes place.
3. Since the sickle cell genes provide resistance to malaria, it would not be beneficial to eliminate
all sickle cell genes. However, biotechnology, or gene therapy, could be used to insert the
malaria resistant genes without causing sickle cell anemia. As of yet, no one has been able to
successfully do this, but perhaps someone will be able to find a vaccine for malaria and a cure
for sickle cell anemia some day in the future.
4. Biotechnology is often used to produce crops that have been genetically altered to be more
resistant to insects and pests. This means that less pesticides will need to be used, and fewer
toxins will be released into the environment.
5. The principle of segregation states that the two alleles present in the reproductive organs of an
organism will be separated, or segregated, into different cells as the gametes (sex cells) form.
As a result, each sex cell will only contain one allele for each gene locus. These segregated
alleles can then combine with a gamete of the opposite sex type, allowing one allele from each
parental gamete to combine to form the offspring.
So, if this heterozygous parent (Aa) combines with a homozygous dominant parent (AA), there is
a 50% chance that a homozygous dominant offspring (AA) is produced. If it combines with a
homozygous recessive parent (aa), there is a 50% chance that a homozygous recessive offspring
is produced (aa). If the heterozygous parent combines with another heterozygous parent, there is
a 25% chance of producing a homozygous dominant offspring, and a 25% chance of producing a
homozygous recessive offspring.
6. Each square represents a segregated outcome. The missing square is a cross between O and O
and could only produce OO, which would be known as simply O.
7. As shown in the chart, UGU codes for cysteine (Cys), but the mutated mRNA codon, UGA, is
a stop codon, which signals the end of transcription. This is a nonsense mutation, which is a
mutation that changes a codon that codes for a specific amino acid into a stop codon.
If the mutation occurs during DNA replication, the mRNA strand that is produced will result in a
shortened protein product. The earlier in a nucleotide sequence that this mutation occurs, the
shorter the resulting protein will be.
8. In an attempt to decrease the number of purebred dogs with genetic conditions, testing on dogspecific genes can help identify carriers of the alleles that result in disease when inherited from
both parents.
The use of sperm donation without testing would continue the risk for inherited disease. Humans
and dogs have different gene locations, so the Human Genome Project does not directly impact
the issue of genetic disease in dogs.
9. If all of the offspring of a homozygous white flowered pea plant and a homozygous purple
flowered pea plant have purple flowers, this means that purple flowers are dominant to white
flowers. If white flowers were dominant, all of the offspring would have white flowers.
10. The genotypes of the plants that were crossed must both have been Yy. A cross between two
Yy parents would result in approximately 1/2 Yy offspring, 1/4 YY offspring, & 1/4 yy
offspring. Of those offspring, approximately 3/4 (YY and Yy) would express the dominant
phenotype. The other 1/4 (yy) would express the recessive phenotype (yy). This is consistent
with the results given for the cross.
A cross between two YY parents would result in 100% YY offspring that expressed the
dominant phenotype. Likewise, a cross between a YY parent and a yy parent would result in
100% Yy offspring that also expressed the dominant phenotype. A cross between two yy parents
would result in 100% yy offspring that expressed the recessive phenotype.
11. By using genetically-engineered bacteria, insulin can now be mass-produced at factories,
thus creating a reliable source for this medicine. This makes insulin cheaper and more readily
available.
12. A nonsense mutation is a mutation that changes a codon that codes for a specific amino acid
into a stop codon. This results in a shortened protein product. The earlier in a nucleotide
sequence that this mutation occurs, the shorter the resulting protein will be.
13. Cells use two different types of RNA to read the instructions on another RNA molecule and
put together the amino acids that make up a protein. This process is known as translation.
Translation takes place in the cytoplasm.
14. AB blood type is an example of codominance.
Codominance is the condition in which a heterozygous individual expresses the phenotype of
two alleles. This happens when neither allele is recessive.
15. -16. Many factors can cause a change in a gene over time. However, most heritable differences
are due to gene shuffling that occurs during the production of gametes. Gametes are
produced when cells undergo meiosis.
Mutations or changes in DNA sequences can occur spontaneously, but this happens infrequently.
17. After the process of DNA replication occurs, each daughter cell receives an exact copy of
the parent cell's DNA.
During DNA replication, the parent cell's double-stranded DNA molecule separates into two
single strands. Then, a new strand of DNA is made that corresponds to each old strand. This
leaves two double-stranded DNA molecules, each with half of the original molecule.
18. In DNA transcription, only a segment of DNA is copied, or "transcribed," to a
complementary strand of messenger RNA.
In DNA replication, the entire length of the DNA molecule is copied so that it can be passed to a
new cell.
19. A DNA molecule contains two complementary strands of DNA arranged in a double helix.
When a DNA molecule replicates, the double helix unwinds as the bonds between the two
strands are broken.
Each of these strands is used as a template for a new strand, which is "built from scratch" as it
binds to the template. So, after the replication process is complete, two daughter DNA molecules
are present, each containing one strand from the parent molecule. This is known as semiconservative replication.
20. Initially, the vast majority of the insect population may be vulnerable to the toxin, and the
technology will achieve its goal. But through sexual reproduction, mutation, and other factors, a
small number of the insects may gain immunity to the toxin. Over time, toxin-resistant
population will expand and the toxin-vulnerable population will fall until the toxin is ultimately
ineffective.
21. The phenotype of an organism refers to the heritable traits, or characteristics, that are
exhibited by that organism. Each specific phenotypic trait can be controlled by one gene,
multiple genes, or a combination of genes and environmental influences.
22. One disadvantage of crops that have been genetically altered to be more resistant to disease
and herbicides is that some of the genes may be transferred to weeds or other undesirable plants
during pollination. The result of this cross-pollination will be an increase in the number of
undesirable plants.
23. Farmers can enhance the genotypic variety of their crops by crossing crops with very
different characteristics, resulting in new combinations of alleles. This genotypic variety will
result in phenotypic variety.
24. The Law of Segregation states that different alleles for the same trait separate when gametes
are formed. Since the alleles separate into different gametes, an offspring could receive a gamete
with one allele or the other. Thus, a mother that is heterozygous for brown eyes (Bb) could pass
either a dominant brown allele (B) or a recessive blue allele (b) for eye color to her offspring.
One allele is no more likely than the other to be passed from parent to offspring.
The segregation of alleles during meiosis increases the genetic variability of the offspring.
25. The nucleus serves as the control center for the cell. It houses the DNA, which contains the
directions for making all of the proteins needed for life functions.
The nucleus transcribes messenger RNA from DNA and releases it, signaling for the
enzymes to be synthesized.
26. From the broadest category to the most specific category, genetic information is organized as
follows:
genome
chromosome
DNA molecule
gene
The genome of an organism refers to its complete genetic makeup and includes the organism's
entire set of chromosomes. Chromosomes are single pieces of DNA, along with the proteins that
package and control their functions. DNA (deoxyribonucleic acid) is a type of nucleic acid that
carries all the instructions for the characteristics of an organism. Genes are specific segments of
DNA that influence a particular trait or group of traits.
27. During meiosis, the process of crossing over results in new combinations of alleles due to the
fact that genetic material is exchanged between homologous chromosomes during this
process.
When crossing over occurs, different parts of chromosomes are exchanged, meaning that genes
(and their alleles) are transferred to new chromosomes. When meiosis separates these
chromosomes, the new combination of alleles is transferred to the offspring, resulting in a new
combination of traits.
28. Frame shift mutations cause the reading frame of the sequence to be shifted. Since a codon
is a sequence of three nucleotides that code for a specific amino acid, any insertion or deletion
that is not a sequence of three causes a frame shift mutation.
Insertions or deletions in multiples of 3 will cause a protein to be shorter or longer than normal,
but the entire sequence of the amino acids will not be shifted.
29. Frame shift mutations cause the reading frame of the sequence to be shifted. Since a codon is
a sequence of three nucleotides that code for a specific amino acid, any insertion or deletion that
is not a sequence of three causes a frame shift mutation. Therefore, the insertion or deletion of 2
nucleotides would cause a frame shift mutation.
Insertions or deletions in multiples of 3 will cause a protein to be shorter or longer than normal,
but the entire sequence of the amino acids will not be shifted.
30. The process shown in the diagram is known as translation, and it involves the production
of proteins from RNA.
A codon is a series of three nucleotides that correspond to a specific amino acid. During the
process of translation, a codon on an mRNA molecule attaches to a ribosome. Then, the
matching tRNA molecule (anticodon) carries the appropriate amino acid to the ribosome where it
is linked to other amino acids via peptide bonds. Once an amino acid is attached, the ribosome
slides to the next codon on the mRNA molecule and repeats the process.
The chain of amino acids continues to grow until the ribosome reaches a stop codon on the
mRNA strand. The stop codon signals that no more amino acids should be added, and the protein
is complete.
31. -32. -33. Since the rabbits display more than two colors (and more than just variations of a color), it is
likely that the rabbits' pattern of inheritance involves multiple alleles. Rabbits actually have four
alleles, of which dark gray (black) is dominant to all other alleles and solid white is recessive.
34. The color of Lisa's baby pythons is a result of incomplete dominance.
Incomplete dominance results when one allele of a gene is not completely dominant over the
other. Instead, both alleles are expressed to some degree, producing a phenotype that appears as a
blend of the two possible homozygous phenotypes.
Incomplete dominance is distinct from codominance. If the baby pythons in this example had
inherited codominant alleles, parts of their bodies would be fully brown, while other parts would
be fully tan with a black diamond pattern.
35. During transcription, enzymes bind to a molecule of DNA. Then, the enzymes unwind and
separate the DNA's double helical strands. As the molecule unwinds, complementary RNA
nucleotides temporarily pair with the nucleotides on one of the DNA strands to form an RNA
molecule. Once base pairing is complete, the new RNA molecule (mRNA) breaks away from the
DNA strands, and the DNA strands reattach to each other.
RNA is very similar to DNA, except RNA contains the nitrogenous base uracil (U) rather than
thymine (T), which is present in DNA.
36. In DNA replication, first DNA helicases break down the hydrogen bonds that link the
complementary nitrogen bases between the old DNA molecules two strands. Proteins hold the
two strands of the old DNA apart and prevent them from reuniting while DNA polymerases add
nucleotides to the exposed nitrogen bases of the old DNA and check the new DNA molecule for
errors.
37. Syndromes such as triple X syndrome, Turner's syndrome, Down syndrome, and Klinefelter's
syndrome occur because of nondisjunction, or the improper separation of the chromosomes
during division. In each of these cases, an extra chromosome (X chromosome for triple X,
chromosome 21 for Down syndrome, etc.) causes symptoms in the offspring. In some
syndromes, such as triple X syndrome, the symptoms are often not very noticeable.
38. Chromosome nondisjunction occurs when homologous chromosomes fail to separate
during meiosis.
The result of chromosome nondisjuction is the formation of one gamete that does not have the
chromosome and another gamete that has two copies of the chromosome.
Zygotes that have a gamete lacking a chromosome usually do not develop to term. Zygotes that
have a gamete with two copies of a chromosome, along with a normal gamete, have a total of
three copies of a chromosome and sometimes do develop, although they often have severe
abnormalities.
Examples of genetic conditions caused by the presence of three chromosomes (also known as a
trisomy) include triple X syndrome, Turner's syndrome, Down syndrome, and Klinefelter's
syndrome.
39. A gene is a set of instructions in the DNA sequence of an organism. Genes are located in
the chromosomes of each cell and specify the sequence of amino acids in an organism's
polypeptides.
Most organisms have two genes for each trait, one on each of the homologous chromosomes in a
cell's nucleus.
40. Complementary DNA strands are held together with hydrogen bonds connecting
complementary nitrogenous bases. Adenine binds with thymine, and cytosine binds with
guanine.
41. The combustion of biodiesel compared to petroleum diesel results in a significant reduction
of hydrocarbons, carbon monoxide, particulate matter, and sulfates. Sulfates are a leading cause
of acid rain.
42. The genotype of an organism can be defined as its inherited combination of alleles. The
phenotype of an organism, on the other hand, is its inherited physical appearance.
43. The discovery of a specific gene mutation that is associated with the severe form of the
disease would help to determine if a patient will have a severe form of the disease in childhood.
The other choices would not be able to distinguish the mild, moderate, and severe forms of the
disease.
44. The subunits of DNA are called nucleotides. Each nucleotide is made of a phosphate group,
deoxyribose, and a nitrogen base. The only portion of the nucleotide that can vary is the nitrogen
base.
45. An allele is one possible form of the gene for a particular trait in a given population.
Humans have two alleles for each trait. These alleles can be dominant or recessive.
Dominant alleles are always expressed in the phenotype (traits) of organisms that have either one
or two copies of the allele. Recessive alleles are expressed only in organisms that have two
copies of the recessive allele.
46. To produce 50% homozygous recessive plants, one of the parents must have contributed
100% of the recessive alleles to the cross; one parent must have the genotype rr. The other parent
must have had one recessive allele and one dominant allele to produce 50% of each characteristic
when paired with the recessive alleles from the homozygous recessive parent; this parent must
have the genotype Rr.
47.
There are many genetic disorders—such as color blindness, hemophilia, and muscular
dystrophy—that are associated with recessive alleles on the X chromosome.
While many females may carry the defective genes, males have the disorders much more often
than females. This is because males have only one copy of the X chromosome and females
have two copies.
If a female is heterozygous (Rr) for hemophilia, she will be a carrier, but will not have the
disease because the defective gene is recessive. If a male has the gene for hemophilia, however,
he will have the disease because he has no functional copy of the gene to make up for the
defective one.
48. Today, several crops have been genetically modified to be more nutritious. For example,
genetically modified rice contains more iron and vitamin A than other types of rice.
49. In the diagram, segments of DNA from homologous chromosomes are crossing over. This
process, which occurs during Prophase I of meiosis, happens randomly and frequently. In fact, it
can even occur at more than one place along the same chromosome.
Meiosis and crossing-over are important processes because they contribute to the genetic
variation found in organisms that undergo sexual reproduction.
50. -51. Phenotypic changes in a fetus may result if a mutation occurs in the gametes.
A mutation in the mother's or father's body cells (such as heart or brain cells) would not be
transferred to the fetus. Only mutations in the gametes are transferred to offspring. Also, a
mutation does not have to be present in both the mother and father's cells for the offspring to
receive the mutation.
52. Biotechnology is a branch of science which combines technology with many other scientific
disciplines such as genetics, molecular biology, and biochemistry. Biotechnology is used in a
wide range of practical fields such as agriculture, food science, medicine, and forensics.
53. When a molecule of double-stranded DNA undergoes replication, it results in two doublestranded DNA molecules, each composed of one new and one old strand. This is known as
semi-conservative replication, and the process is shown below.
54. Gene splicing involves cutting a segment of DNA from one organism and inserting the
segment into the DNA sequence of another organism. Gene splicing has many useful
applications, including genetically engineering pest-resistant plants and insulin producing
bacteria.
55. The fact that each plant gets only one allele from each parent plant is detailed in the Law of
Segregation.
In normal body cells there are two copies of each chromosome. Each chromosome has its own
copy of an allele, so in a body cell, two different alleles can be present for one trait. However, in
gametes, there is only one copy of each chromosome and one allele present. Thus, each new
organism receives only one allele from each parent.
56. Organelles must interact with each other chemically and physically when carrying out an
organism's life processes.
For example, during protein synthesis:




DNA is transcribed in the nucleus into mRNA.
The mRNA travels into the cytoplasm, attaches to ribosomes, and is translated into a
protein.
The protein is pushed into the ER (endoplasmic reticulum) where it is stored for later use
or packaged into vesicles.
These vesicles can then be transported to the cell membrane and exported or to the Golgi
apparatus where a more complex molecule may be formed. These complex molecules can
then be repackaged into vesicles and transported to the cell membrane for export.
57. The law of independent assortment states that the inheritance of one trait will not affect the
inheritance of another trait. In other words, alleles assort independently of one another during
gamete formation.
If genes follow the law of independent assortment, this means that receiving a dominant allele
for one trait does not have any influence on the probability of the gamete receiving a dominant
allele for another trait. In Lupe's cross, if a gamete receives a dominant allele for flower color,
this has no effect on the probability of the gamete receiving a dominant allele for pea shape.
58. A cross between heterozygous parents would produce ratios of approximately 1/4
homozygous dominant (black hair), 1/2 heterozygous (black hair) and 1/4 homozygous recessive
(brown hair). This predicts about 3/4 of the offspring would have black hair and 1/4 would have
brown hair. It is important to remember that probability is not certain, so it would not be unusual
to find actual results that vary wildly from predicted numbers, especially in small offspring sizes.
59. Errors that are made during DNA replication may result in mutations.
Mutations are a source of variation within species. Some mutations are harmless, while others
may be harmful to an organism.
60. Genotypic variation occurs when alleles are randomly sorted during sexual
reproduction. Since each offspring receives a different combination of alleles from the parent
organisms, phenotypic diversity results. Genotypic and phenotypic traits can be predicted using
Punnett squares.
61. Polygenic traits are traits that are controlled by more than one pair of genes, so multiple
independent pairs of genes have similar effects on the same trait. Human height, body form, and
skin color are examples of polygenic traits.
62. A change in the nucleotide sequence of an organism's genetic material is known as a
mutation. Mutations can be caused by many factors, including copying errors during replication.
Sometimes, mutations create changes in an organism's phenotype or in the phenotype of the
organism's offspring. At other times, however, they have no effect on the organism at all.
Mutations that have no effect on an organism are called silent mutations.
63. -64. Chromosome inversion occurs when a section of the chromosome breaks out and is
reinserted backwards. Inversions usually do not cause physical or mental abnormalities in an
individual as long as no genetic information is lost during the inversion.
65. -66. Crossing-over is a process that typically occurs during prophase I of meiosis. During this
phase, homologous chromosomes are held tightly together which enables the exchange of
segments of DNA. Crossing-over is an important process because it introduces more genetic
variation into a species.
67. Carla is heterozygous for the trait of eye color. She has one gene for blue eyes, and one for
brown eyes. Since the gene that codes for brown eye color is dominant, the trait for this eye color
will be expressed, and Carla will have brown eyes.
68. -69. As mentioned in the question, a calico pattern can only result if a cat has two X
chromosomes, but in order for a cat to be male, it must also possess a Y chromosome. So, a male
calico cat must have XXY chromosomes.
This pattern is also possessed by humans with Klinefelter's syndrome.
70. Crossing over, which occurs in prophase I of meiosis, is a process by which homologous
chromosomes swap homologous segments of DNA. This helps produce gametes that are unique
from the "parent genome", thus increasing genetic variation.
71. Biotechnological techniques, such as the analysis of DNA sequences, allows for the
relatedness among individuals to be determined. This usage is demonstrated by the tale of Anna
Anderson.
72. The successful use of gene therapy would allow doctors to cure, rather than simply treat,
genetic diseases.
73. Ribosomes are RNA and protein complexes that are found in all cells. These complexes help
cells during protein translation by joining amino acids together to form polypeptides.
74. DNA is a nucleic acid that contains the genetic instructions, or blueprint, of an organism's
development and functioning. DNA sequences are copied into RNA during transcription, and
then the RNA is copied into proteins during translation. Instructions coded by DNA sequences
are translated into proteins which express an organism's physical traits. That is, the proteins
determine the phenotype of an organism.
75. Each nucleotide is made of a phosphate group, deoxyribose, and a nitrogen base.
Deoxyribose is a five-carbon sugar. The only portion of the nucleotide that can vary is the
nitrogen base. DNA has four types of nitrogen bases: adenine, thymine, cytosine, and guanine.
Adenine and Guanine are purines, or nitrogen bases made of two rings of carbon and nitrogen
atoms. Thymine and cytosine are pyrimidines, or nitrogen bases made of a single ring of carbon
and nitrogen atoms.
76. All cells contain DNA, which provides information for the cells to make different kinds of
proteins.
The proteins made by DNA have many jobs, such as acting as enzymes, storage, transport, and
defense against diseases.
77. An allele is one possible form of a gene that codes for a particular trait. Humans have two
alleles for most traits. These alleles can be dominant or recessive. Dominant alleles are always
expressed in the phenotype of an organism that has either one or two copies of the allele.
Recessive alleles are expressed only if an organism has two copies of the recessive allele.
78. The process of DNA replication begins with one double-stranded molecule of DNA. The
two strands of this molecule separate during replication, and DNA polymerases add
complementary nucleotides to each strand. The end results of DNA replication are two identical
DNA molecules.
79. Gene splicing involves cutting a segment of DNA from one organism and inserting the
segment into the DNA sequence of another organism. For example, a segment of human DNA
that codes for insulin production can be inserted into bacterial DNA. This causes the bacterium
to begin producing human insulin which diabetics can then use to treat their disease.
80. A mutation is a random change in a cell's genetic code. Mutations can occur in either sex or
body cells.
Mutations can be caused by a variety of different things. For example, mutations can
spontaneously occur during DNA replication. Environmental factors, such as exposure to
radiation, can also cause mutations.
81. When environmental conditions change, it is more likely that at least some members of a
species will survive if there is variation among the members. This is because the variant
organisms within the species are able to respond differently to the environmental changes.
82. Bacteria that help clean up pollutants in the environment are called bioremediating bacteria.
These bacteria will enable people to easily clean up spilled pollutants in the environment.
83. Typically, there are two alleles for a trait—a dominant trait and a recessive trait. The blood
type trait, however, has three alleles, which correspond to the blood types A, B, and O. The A
and B alleles are dominant to the O allele, but they do not show dominance over each other. The
result is that if a person has an A allele and a B allele, he or she will have type AB blood.
Mrs. Smith's parents have blood types A and B. Since Mrs. Smith has blood type A, it logically
follows that she must carry one A allele and one recessive antigen-free O allele obtained from
her mother, who has type B blood. (If her parents had both been homozygous for their blood
types, Mrs. Smith could only have had AB blood. Her mom must have been heterozygous (BO)
for her blood type in order for Mrs. Smith to have blood type A.)
So, if Mrs. Smith's blood type (AO) is crossed with Mr. Smith's blood type (AB), their offspring
will have a 50% chance of being blood type A (includes AA and AO), a 25% chance of being
blood type AB, and a 25% chance of being blood type B (BO only).
84. The endoplasmic reticulum aids in the transportation of proteins, including integral
membrane proteins.
The Golgi apparatus and endoplasmic reticulum work closely together in the total process of
modifying, packaging, and transporting proteins.
85. The fact that the cross of a tall blue flower and a short purple flower leads to four varieties of
flowers is an example of the Law of Independent Assortment.
Since each allele and trait are sorted independently of each other, any combination of traits and
alleles is possible.
86. Genetic information is stored in DNA molecules. This information is passed from one
generation to the next when parents transfer their DNA to their offspring.
Genes are segments of DNA. Genes in DNA code for the production of proteins, which cause
traits to be expressed.
An offspring's traits are similar to its parents' traits because it inherits DNA and genes from its
parents. The offspring's traits are not identical, however, because some of the DNA comes from
the mother and some of the DNA comes from the father.
87. An autosomal trait is a physical or biochemical characteristic arising from genes located on
chromosomes that are not gender-determining.
Traits coded for by genes on all human chromosomes other than X and Y chromosomes are
autosomal traits.
88. True-breeding plants are those that produce offspring with the same phenotype as the parents
when self-fertilized. This means that the parents must have been homozygous for the trait under
study. Whether the green versus yellow pods are controlled by one gene locus or multiple ones,
the F1 generation of a cross between homozygous dominant and homozygous recessive parents
will always resemble the dominant parent trait. Thus, the F1 generation of this cross will result in
100% yellow offspring.
89. Edible vaccines are much easier to administer than traditional vaccines that must be injected.
Edible vaccines would be cheaper to manufacture than traditional vaccines because the vaccine
would be produced by the plant as it grows.
90. Vaccines made by genetic engineering avoid the problem of possibly causing an infection in
the patient by modifying a harmless organism to have the surface proteins of a disease-causing
organism. The harmless organism is injected into a person, and that person's immune system
learns to recognize the dangerous surface proteins without having to actually come into contact
with the disease-causing organism to which those proteins belong.
91. Different enzymes can be used to cut, copy, and move segments of DNA.
Characteristics produced by the segments of DNA can then be expressed when these segments
are inserted into new organisms, such as bacteria.
92. As shown on the chart, both CCU and CCC code for proline (Pro). This means that the
mistake made during DNA replication in the nucleotide sequence in the question will result in a
silent mutation, which is a mutation that does not result in a change in the amino acid sequence
of the resulting protein.
Most amino acids are coded by several different codon sequences. Therefore, a mutation can
occur that changes the nucleotide sequence, but does not change the resulting amino acid. These
mutations are referred to as silent because they do not change the product of protein translation
and cannot be detected without sequencing the gene.
93. In sexually-reproducing organisms, meiosis helps contribute to genetic variation. Meiosis is
the process by which sexually-reproducing organisms produce gametes, or sex cells. Meiosis
produces gametes that are unique from each other and from the "parent genome". The gametes
will be passed on to future offspring.
94. Since, by nature, all viruses insert their genetic material into their host cells as part of their
replication cycle, scientists often use viruses to insert specific genetic sequences into cells.
This process is very intricate, however, and requires the scientist to have significant knowledge
about the virus' genome. The disease causing parts of the virus must be removed and replaced
with the desired DNA sequence, but the parts that cause the virus to replicate must remain intact
in order for this procedure to work.
95. Genetic engineering, recombinant DNA technology, and gene splicing are methods that are
commonly used to enhance cells through the introduction of new DNA into the cells. In order to
do this, however, specific scientific knowledge about the natural system being modified is
required.
To better understand this concept, genetic engineering can be likened to enhancing a car. It is
possible, for example, to make a better and faster car by changing out various parts of the car the engine, the wheels, etc. But it is essential to fully understand how a car works and where
certain parts ought to go before enhancement can begin. Putting new wheels where the engine
ought to go, for example, won't enhance the car. Instead, it will make it less functional.
96. DNA contains instructions for making the different molecules, such as proteins, that the cell
needs for growth and function. To use these instructions, the DNA must first be transcribed into
mRNA. Then the mRNA is translated into proteins.
97. Pest- and disease-resistant plants help farmers in many ways. This type of geneticallyengineered plant allows the farmers to spray fewer pesticides on their crops. This saves farmers
money and is beneficial to the environment, because it avoids the introduction of dangerous
chemicals into local soil, groundwater, and runoff.
98. Gene flow between similar species is a common occurrence. It is possible for geneticallyengineered genes in a crop plant to transfer to related species of wild plants. This could cause
multiple problems. For example, if the genetically-engineered gene makes the plant immune to a
weed killer, then wild plants that are considered weeds by the farmer would no longer be
controllable with weed killers.
99. A silent mutation is a mutation that does not result in a change in the amino acid sequence
of the resulting protein.
Most amino acids are coded by several different codon sequences. Therefore, a mutation can
occur that changes the nucleotide sequence, but does not change the resulting amino acid. These
mutations are referred to as silent because they do not change the product of protein translation
and cannot be detected without sequencing the gene.
100. Chromosome translocation is caused when material is exchanged between two
chromosomes or part of one chromosome becomes fused onto another chromosome. Some
human disorders are caused by chromosome translocation, such as cancer, infertility, and
translocation Down syndrome.
Translocation Down syndrome is caused by a piece of chromosome 21 fusing onto another
chromosome. It accounts for less than 5% of the total cases of Down syndrome reported.