DNA, RNA, Mitosis and Meiosis – JANUARY DIPLOMA EXAMS
JANUARY 1996
Use the following information to answer the next question.
In the life cycle of this jellyfish, the polyp stage is sessile. The medusa is a diploid,
freeswimming animal. The planula is ciliated and motile.
1. Meiosis occurs in this life cycle when
A. an egg and a sperm fuse to form a zygote
B. a mature polyp produces a medusa
C. a planula produces a young polyp
D. a medusa produces gametes
1
Use the following information to answer the next question.
Life Cycle of a Typical Animal Life Cycle of a Typical Plant
2. Which structures normally have a haploid number of chromosomes?
A. Seed plant spores and animal zygotes
B. Seed plant spores and animal gametes
C. Seed plant zygotes and animal zygotes
D. Seed plant gametes and animal zygotes
Use the following information to answer the next question.
Some Events that Occur During Meiosis
1 Gametes are produced.
2 Spindles form and homologous pairs of chromosomes separate.
3 Centromeres divide and chromatid pairs separate.
4 Chromosomes are replicated.
Numerical Response
01. Provide the correct sequence of these four events that occur during meiosis.
(Record your four-digit answer in the numerical-response section of the answer sheet.)
Answer: __4231_
2
Use the following information to answer the next question.
Mature red blood cells lack a nucleus. Approximately 2 million red blood cells are destroyed
every second in the circulatory system. All blood cells differentiate from a common source—
a population of pluripotent stem cells in the bone marrow. Pluripotent refers to the potential
of these cells to form any type of blood cell.
3. Which statement best explains why the number of red blood cells in the human body
can be maintained?
A. Mature red blood cells retain sufficient mRNA for replication and transcription.
B. Pluripotent stem cells undergo cell division continuously to produce new red
blood cells.
C. Other types of mature blood cells undergo differentiation to form new red blood
cells.
D. Mature red blood cells, before they are destroyed, undergo cytoplasmic cleavage
repeatedly to produce more red blood cells.
3
Jan 1997
Use the following information to answer the next question.
A mutation is the cause of fatal familial insomnia and Creutzfeldt/Jakob disease. One
symptom of fatal familial insomnia is a drastically reduced heart rate. Individuals with
Creutzfeldt/Jakob disease experience personality changes. Both diseases result from lesions
or damage in the brain caused by the accumulation of abnormal clumps of prion proteins.
Prion proteins are found in the brain tissue of humans. The mutation occurs in a gene coding
for a prion protein. One nucleotide in DNA triplet 178 (CTG) is changed, resulting in a new
triplet (TTG).
4. The mutated DNA triplet 178 would be transcribed to the mRNA codon
A. AAC
B. TTG
C. UUG
D. GAC
Use the following information to answer the next two questions.
Human oxytocin and ADH are two hormones with very similar molecular structures but very
different functions. In the following diagram, all amino acids are the same except those labeled
“1” and “2.”
5. The two point-mutations in DNA that would change the code for oxytocin to ADH
occur
A. at 1, where T would be replaced by A
at 2, where A would be replaced by C
B. at 1, where A would be replaced by T at 2,
where C would be replaced by A
C. at 1, where U would be replaced by A at 2,
where U would be replaced by G
D. at 1, where U would be replaced by A at 2,
where G would be replaced by U
4
Use the following information to answer the next question.
Adenine Base Composition of DNA from Some Organisms (%)
Organism
Human
Ox
Salmon
Sea Urchin
Cell Type
Skin
Nerve
Muscle
Muscle
Adenine
30.4
29.0
29.7
32.8
6. Although the adenine base composition of DNA from the above organisms is very
similar, these organisms vary greatly in their characteristics. The cause of this
variation is that the DNA molecules of the respective organisms contain different
A. pairings of nitrogen bases
B. sugars in their nucleotides
C. sequences of nitrogen bases
D. proteins in their nucleotides
Use the following information to answer the next question.
Cellular Processes
7. Which row correctly identifies processes 1 and 2 and indicates the locations in which
these processes occur?
Row
A.
B.
C.
D.
Process 1
transcription—nucleus
translation—cytoplasm
translation—nucleus
transcription—cytoplasm
Process 2
translation—cytoplasm
transcription—nucleus
transcription—cytoplasm
translation—nucleus
8. Using the DNA sequence TCAGGA, the dipeptide formed is
A. threonine, glycine
B. threonine, proline
C. serine, proline
D. serine, glycine
5
Use the following information to answer the next question.
Some Steps in the Production of Recombinant DNA
23. Which row correctly identifies the enzyme-directed processes 1, 2, and 3?
Row
A.
B.
C.
D.
Process 1
ligase
restriction enzymes
ligase
restriction enzymes
Process 2
restriction enzymes
restriction enzymes
ligase
ligase
Process 3
ligase
ligase
restriction enzymes
restriction enzymes
Use the following information to answer the next question.
Gel electrophoresis is a technique used to separate DNA or protein fragments. A sample of
DNA is fragmented by enzymes, and then the sample is placed in a gel. An electric current is
passed through the gel. Because the DNA is electrically charged, the DNA fragments migrate.
The following gel plate, with distinct bands of DNA, results.
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9. Which statement about the DNA fragments on the gel plate is correct?
A. Band 1 has more base pairs than band 5.
B. Band 3 has more base pairs than band 2.
C. Band 1 has the least number of base pairs.
D. Band 5 has the largest number of base pairs.
Use the following information to answer the next question.
To investigate a sexual assault, a forensic scientist collected a semen sample and analyzed its
DNA content in the laboratory. The DNA “fingerprint” that resulted from this analysis was
compared with DNA “fingerprints” from three suspects. As a result of the comparisons, two
suspects were released and the third suspect was charged.
10. The use of this new technology is valuable for the conviction of criminals because,
with the exception of identical twins, every individual is unique with regard to the
A. type of nucleotides found in DNA
B. type of proteins produced by DNA
C. protein sequence in some segments of DNA
D. nucleotide sequence in some segments of DNA
Use the following information to answer the next three questions.
During the cell cycle, cells in growing tissue normally progress through
interphase:
• stage 1—cells grow, carry out normal metabolism, and produce more organelles
• stage 2—DNA replication, chromosome duplication, and cell growth occur
• stage 3—cell growth occurs
and mitosis.
Human cells were cultured for a day in a nutrient-rich medium. The DNA content of a
typical nucleus was determined every hour, and the data collected were graphed.
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11. The process that occurs during interval K–L is
A. cytokinesis
B. chromatid separation
C. replication of genetic material
D. synapsis of homologous chromosomes
12. On the graph, N likely indicates the completion of which mitotic event?
A. Prophase
B. Anaphase
C. Telophase
D. Metaphase
13. On the graph, interval N–P corresponds to the period between the end of
A. mitosis and the beginning of stage 1
B. stage 2 and the beginning of stage 3
C. stage 1 and the end of stage 2
D. stage 1 and the end of mitosis
14. One difference between mitosis and meiosis is that, during mitosis,
A. one replication of chromosomes and one division occurs
B. one replication of chromosomes and two divisions occur
C. two replications of chromosomes and one division occurs
D. two replications of chromosomes and two divisions occur
Use the following information to answer the next question.
Chromosome Number of a Horse
Horse, Equus caballus 66 (2n)
15. Starting from a single cell, spermatogenesis in horses produces
A. one cell with 33 chromosomes
B. two cells, each with 66 chromosomes
C. four cells, each with 33 chromosomes
D. three cells, each with 22 chromosomes
16. A human with Klinefelter Syndrome has 47 chromosomes and has the XXY
chromosome set instead of XY. From what does this abnormality result?
A. The process of mitosis does not occur properly.
B. An error in replication produces an extra X chromosome.
C. Crossing over results in the formation of an extra chromosome.
D. Nondisjunction occurs in either the formation of the sperm or the egg.
8
Use the following information to answer the next question.
In May 1934, Elzire Dionne gave birth to five identical daughters two months prematurely.
No one expected the tiny infants to live. But Annette, Emilie, Yvonne, Marie, and Cecile
became the first quintuplets ever to survive.
17. The fact that the Dionne Quintuplets were identical indicates that they developed
from
A. one ovum that was fertilized by five different sperm cells
B. five separate eggs that were released from an ovary simultaneously and then
fertilized
C. one zygote that split into five separate surviving embryos during initial
mitotic divisions
D. one ovum that underwent mitosis to produce five eggs, each of which was
fertilized by one sperm cell
9
JANUARY 1998
Use the following information to answer the next three questions.
Males and females of different lizard species can interbreed, but often the offspring of these
matings are sterile. However, some of the female offspring, as adults, produce diploid eggs
that develop without fertilization. The offspring of these “virgin births” all reproduce in the
same way as their mother.
—from Richardson
18. Phenotypically, generation III offspring will be
A. female, and each individual will be genotypically different
B. female, and each individual will be genotypically identical
C. 50% male and 50% female, and will be genotypically different
D. 50% male and 50% female, and will be genotypically identical
19. If a new disease-causing organism from which lizards have no protection reaches an
island where a uniform population of lizards reproduce only asexually, a likely
outcome is that
A. rapid extinction of the lizard population will occur
B. the lizard population will begin to reproduce sexually
C. gene frequencies will change in the lizard population’s gene pool
D. unique individuals in the lizard population will not find a mating partner
10
Numerical Response
02. From the list below, identify the processes that correspond to A, B, C, and D in the
diagram on the previous page.
Normal Processes
1 Fertilization
2 Meiosis
3 Mitosis
(Record your four-digit answer in the numerical-response section of the answer sheet.)
Answer: Process __2__ __1__ __3__ _3___
A
B
C
D
__________________________
Use the following information to answer the next question.
Many adult newts and salamanders have a remarkable ability to regenerate amputated limbs.
After amputation of a foot, a newt will regenerate the lost foot. However, if a newt has its foot
amputated and receives a particular dosage of vitamin A, the animal grows back a whole new
forelimb, not just the foot!
—from Pietsch
20. A logical interpretation that can be drawn from this information is that vitamin A may
play a major role in growth by
A. increasing the amount of mitosis
B. increasing the amount of meiosis
C. decreasing the amount of mitosis
D. decreasing the amount of meiosis
Use the following information to answer the next three questions.
Nondisjunction in meiosis disrupts the chromosome number in the gametes that are produced.
Nondisjunction can occur in either the first or second division of meiosis and results in various
genetic disorders.
21. One homologous pair of chromosomes in a human spermatogonium undergoes
nondisjunction during the first division of meiosis. After meiosis is completed, what
number of chromosomes will the four newly produced cells contain?
A. All four cells will have 23 chromosomes.
B. Two cells will have 22 chromosomes, and two cells will have 24 chromosomes.
C. One cell will have 22 chromosomes, and three cells will have 24 chromosomes.
D. One cell will have 24 chromosomes, and three cells will have 22 chromosomes.
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22. Which expression of chromosome content represents somatic cells in people with
trisomy disorders such as Down syndrome?
A. n – 1
B. n + 1
C. 2n – 1
D. 2n + 1
Use the following additional information to answer the next question.
Polyploids are organisms with three or more complete sets of chromosomes. If a diploid
organism is 2n, then a triploid is 3n, a tetraploid is 4n, and so on.
All major groups of seed plants have some polyploid members. Plant polyploids are larger
than plants with 2n chromosome number. Plant polyploids with even chromosome numbers
(e.g., 4n) can usually produce pollen and seeds. Plant polyploids with odd chromosome
numbers (e.g., 5n) are nearly always sterile.
23. If a diploid plant and a tetraploid plant, each capable of normal meiosis, were crossed,
the chromosome number in their offspring would be
A. 2n
B. 3n
C. 4n
D. 6n
Use the following information to answer the next question.
A Cellular Structure Found During Mitosis
24. This diagram of a cellular structure shows
A. one crossed-over pair of chromosomes
B. two homologous chromosomes
C. one tetrad of chromatids
D. two sister chromatids
__________________________
Use the following information to answer the next question.
The San Diego Zoo is preserving DNA from hundreds of species by freezing cell samples in
its Centre for the Reproduction of Endangered Species. The cell specimens are often from
individuals in wild populations that are chosen for distinctive characteristics.
—from Vedantam
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25. To obtain all the representative DNA of an organism, it would be necessary to collect
only
A. an egg
B. a sperm
C. a body cell
D. a cell from each type of body tissue
Numerical Response
03. Of the nitrogen-based molecules present in the DNA of sea urchins, 17.5% are
cytosine molecules. Calculate the percentage composition of thymine in sea urchin
DNA.
(Record your answer as a percentage rounded to one decimal place in the numerical-response
section of the answer sheet.)
Answer: __32.5__%
JANUARY 1999
Use the following information to answer the next two questions.
Biologists using light microscopes to study mitosis noticed that the nuclear membrane of a cell
disappeared and then re-formed during the process. They could not explain this disappearance
until they used electron microscopes to view mitotic cells. These observations revealed a large
number of vesicles (small bubble-shaped structures bounded by membranes) that appeared in
the cytoplasm during mitosis and then disappeared when mitosis was nearly complete. During
mitosis, the nuclear membrane appeared to disintegrate and form these tiny vesicles. The
vesicles disappeared when new nuclear membranes formed.
26. The vesicles observed with the aid of an electron microscope appeared and
disappeared, respectively, during
A. prophase and anaphase
B. prophase and telophase
C. interphase and anaphase
D. interphase and telophase
27. During mitosis, the chromosomes
A. are located at the cell equator during prophase
B. are located at the cell equator during telophase
C. move toward the poles of the cell during anaphase
D. move toward the poles of the cell during metaphase
13
28. One aspect of meiosis that is different from mitosis, is that normally by the end of
meiosis
A. two diploid cells result
B. four diploid cells result
C. two haploid cells result
D. four haploid cells result
29. As cells age, there is an increase in DNA damage and a decrease in DNA repair
processes. The initial effect is
A. a decrease in ATP synthesis
B. an increase of cancerous cells
C. the production of altered proteins
D. the production of abnormal mRNA
30. Certain disorders result if an extra chromosome is present in all nucleated cells of the
body (trisomy) or if a chromosome is missing from all nucleated cells of the body
(monosomy). These disorders arise because of nondisjunction, a malfunction that
occurs during
A. DNA replication
B. RNA transcription
C. telophase of mitosis
D. anaphase of meiosis
Use the following information to answer the next question.
Portion of Insulin Protein
Phenylalanine–Valine–Asparagine–Glutamine–Histidine
31. What is the strand of DNA that would code for this portion of insulin?
A. AAG CAA TTA GTT GTA
B. AAA CAA TTC CAC CTA
C. CAC GAG AAC GTA TTC
D. TTC GTA AAC GAG CAC
32. DNA is structurally different from RNA in that DNA
A. contains uracil and is composed of double strands
B. contains adenine and is composed of single strands
C. contains guanine and is composed of single strands
D. contains thymine and is composed of double strands
33. Analysis of a DNA sample showed that 15% of the nitrogen-base molecules present
were adenine molecules. This sample would likely contain
A. 15% thymine
B. 15% uracil
C. 85% thymine
D. 85% uracil
14
Use the following information to answer the next two questions.
In DNA replication, the two strands of the double helix separate and a new strand forms
along each old one. Each new DNA molecule has one old and one new strand.
34. The name of the old DNA strand and the site of DNA replication are identified in row
Row
A.
B.
C.
D.
Name of Old Strand
a template
a template
haploid
haploid
Site
nucleus
cytoplasm
nucleus
cytoplasm
35. The backbone of a DNA molecule and the composition of A, C, T, and G are
identified in row
Row
A.
B.
C.
D.
DNA Backbone
phosphate groups
purines
pyrimidines
sugars and phosphate
groups
A, C, T, and G
deoxyribose sugars
deoxyribose sugars
nitrogen-containing bases
nitrogen-containing bases
15
JANUARY 2000
Use the following information to answer the next question.
The Life Cycle of Ulva—a green alga
—from Campbell, 1993
36. Which structures in the life cycle of the Ulva are haploid (monoploid)?
A.
B.
C.
D.
Zoospores and the zygote
The sporophyte and the zygote
Zoospores and the gametophytes
The sporophyte and the gametophytes
16
Use the following information to answer the next four questions.
Chromosome Content of Human Cells During a Series of Events
37. In humans, what process must have occurred to obtain the cells at U?
A. Mitosis
B. Meiosis
C. Fertilization
D. Differentiation
38. In humans, what process occurs between U and V?
A. Mitosis
B. Meiosis
C. Fertilization
D. Differentiation
39. In humans, what process must occur before cell V forms cells W and X?
A. Mitosis
B. Meiosis
C. Recombination
D. Nondisjunction
40. In humans, cells Y and Z represent individual cells that
A. are two eggs
B. will no longer divide
C. will become a 4n cell
D. could develop into identical twins
17
Use the following information to answer the next question.
Phases of Mitosis
1 Anaphase
2 Metaphase
3 Prophase
4 Telophase
Numerical Response
03. The phases of mitosis in the sequence in which they occur are
__3__ , __2__ , __1__ , and __4__.
(Record your four-digit answer in the numerical-response section on the answer sheet.)
Use the following information to answer the next question.
Erwin Chargaff found that the relative amount of each of the base pairs that make up DNA
varies from species to species. He analyzed a sample of DNA from Escherichia coli (a
bacterium) and found that 23.6% of the nitrogen base molecules present in this sample were
thymine.
—from Curtis, 1983
41. In this sample of Escherichia coli DNA, the percentage of the nitrogen base
molecules that would be adenine is
A. 76.4%
B. 38.2%
C. 23.6%
D. 11.8%
Use the following information to answer the next two questions.
Although most strains of the bacterial species Vibrio cholera are harmless, the 01 strain
produces a toxin that binds to cells of the small intestine, causing rapid depletion of salts
and water, which, if not replaced, can be lethal in humans. This disease is known as
cholera.
The transformation from harmless to harmful bacterial strains is thought to be caused by a
virus that transfers the cholera toxin gene (CTX) from one bacterial strain and places it
into another. Researchers can mimic this process by using current technologies.
—from Glausiusz, 1996
42. The sequence of events that would enable researchers to incorporate the CTX gene
into bacterial DNA would be to
A. first open the bacterial DNA with ligase enzymes, then position the CTX gene in
the DNA, and then join the DNA by restriction enzymes
B. first open the bacterial DNA with restriction enzymes, then position the CTX
gene in the DNA, and then join the DNA by ligase enzymes
C. first position the CTX gene in the DNA, then open the DNA with ligase enzymes,
and then join the DNA by restriction enzymes
D. first position the CTX gene in the DNA, then open the DNA with restriction
enzymes, and then join the DNA by ligase enzymes
18
Use the following information to answer the next two questions.
Some people have condemned the use of food preservatives because they may cause cancer.
A researcher has found contradictory evidence that suggests that two widely used food
preservatives actually increase levels of natural cancer-fighting agents in laboratory animals.
The preservatives BHA and BHT increase the activity of a gene that controls the production of
an enzyme. This enzyme helps destroy cancer-causing substances (carcinogens) before they
trigger the development of tumours.
—from Pearson et al, 1983
43. The most direct relationship between a gene and an enzyme is that
A. an enzyme causes a gene to destroy carcinogens
B. the sequence of nucleotides in a gene determines the structure of an enzyme
C. each gene contains the code needed to construct many different types of enzymes
D. the sequence of amino acids in an enzyme is unrelated to nucleotide sequence in a
gene
Use the following additional information to answer the next question.
Some Events that Occur Following BHA or BHT Exposure
1 The polypeptide folds into an enzyme shape.
2 tRNAs transport amino acids to the ribosomes.
3 A polypeptide is released from the ribosomes.
4 mRNA leaves the nucleus and attaches to ribosomes in the cytoplasm.
Numerical Response
05. The sequence of events that results in the production of the cancer-fighting enzyme
is ___4_ , _2___ , __3__ , and __1__.
(Record your four-digit answer in the numerical-response section on the answer sheet.)
JANUARY 2001
Use the following information to answer the next two questions.
Mature Human Oocyte
Human Sperm
19
44. The difference in size between the human oocyte and sperm is mostly due to the
A. difference in magnification of the two photographs
B. distance that the sperm must travel in order to reach the oocyte
C. amount of cytoplasm present in the oocyte as compared with that in the
sperm
D. number of chromosomes in the nucleus of the oocyte as compared with the
number in the sperm
45. The nucleus of a human oocyte would normally be
A. diploid and contain 23 chromosomes
B. diploid and contain 46 chromosomes
C. haploid and contain 23 chromosomes
D. haploid and contain 46 chromosomes
Use the following information to answer the next three questions.
Meiosis is a process that results in the reduction of the chromosome number from diploid
to haploid. Sometimes chromosomes fail to separate, which results in an abnormal number
of sex chromosomes.
—from Levine and Miller, 1991
46. Process Z represents
A. fertilization
B. crossing-over
C. nondisjunction
D. spermatogenesis
20
Use the following additional information to answer the next question.
Scientists studying Klinefelter and Turner syndromes wanted to determine which of several
hypotheses about gender determination was most likely. These hypotheses were:
• presence of a Y chromosome causes maleness
• lack of a second X chromosome causes maleness
• the presence of two X chromosomes causes femaleness
• the Y chromosome is not involved in gender determination
Evidence noted by the scientists included the following points.
• Individuals with Klinefelter syndrome (XXY) have genitalia and internal ducts that are
usually male, but their testes are underdeveloped.
• Individuals with Turner syndrome (XO) have female external genitalia and internal ducts;
however, the ovaries are underdeveloped.
—from Cummings and Klug, 1997
47. This evidence best supports which of the scientists’ hypotheses about gender
determination?
A. The presence of a Y chromosome causes maleness.
B. The lack of a second X chromosome causes maleness.
C. The presence of two X chromosomes causes femaleness.
D. The Y chromosome is not involved in gender determination.
Use the following additional information to answer the next question.
Partial Human Karyotype
48. This partial human karyotype represents the last six chromosome pairs, in numerical
order. The karyotype presented is that of a
A. male with trisomy 21
B. female with trisomy 21
C. male with Turner syndrome
D. female with Turner syndrome
21
Use the following information to answer the next question.
Conifer Life Cycle
Numerical Response
05. Identify the stages in the conifer life cycle, as numbered above, that correspond with
the letters that represent these stages on the diagram.
Stages:
Diagram:
__1__
A
__1__
B
__2__
C
__2__
D
(Record your four-digit answer in the numerical-response section on the answer sheet.)
Use the following information to answer the next three questions.
Researchers have found a gene known as p53. It codes for a protein that binds to specific
areas of DNA and activates them. This causes the production of a set of proteins that halts
cell division or, in some cells, activates the cell’s suicide program (apoptosis). The p53 gene
is activated when a cell is damaged and/or undergoes a DNA mutation.
—from Seachrist, 1996
49. The normal function of the p53 gene is likely to
A. encourage a cell to undergo mitosis
B. encourage a cell to undergo meiosis
C. prevent an abnormal cell from reproducing
D. prevent the transcription of a cell suicide gene
22
Use the following additional information to answer the next two questions.
Research on the p53 gene was initially done with cancer cells obtained from a laboratory
animal. These cells were grown in a petri dish. A cell with two normal p53 alleles was found
to have normal cell division. Cells with one normal and one mutated p53 allele were also
found to have normal cell division. Cells that had mutations in both p53 alleles were unable
to control cell division and were associated with cancer.
50. The initial research findings described above
A. demonstrate that the activated p53 gene causes cancer in lab animals
B. demonstrate that the p53 protein causes the formation of cancer cells
C. indicate that the normal p53 gene is responsible for preventing cancer in all
mammals
D. indicate that the normal p53 gene is responsible for preventing cancer under
laboratory conditions
51. Gene therapy that might stop uncontrolled cell division due to the mutant p53 allele
would require
A. one functional p53 allele to be successfully inserted into cancer cells
B. two functional p53 alleles to be successfully inserted into cancer cells
C. one functional p53 allele to be successfully removed from cancer cells
D. two functional p53 alleles to be successfully removed from cancer cells
52. Which of the following rows correctly describes a DNA molecule?
Row
A.
B.
C.
D.
Components
amino acids, sugars, and bases
amino acids, sugars, and bases
phosphates, sugars, and bases
phosphates, sugars, and bases
Backbone
sugars and bases
sugars and amino acids
sugars and bases
sugars and phosphates
Molecules
that form the
links between
two strands
amino acids
bases
phosphates
bases
Use the following information to answer the next question.
A section of template DNA contains the following proportions of bases:
adenine—20%
thymine—30%
cytosine—10%
guanine—40%
53. The proportions of three of the mRNA nucleotides produced from this DNA are
A. 20% adenine, 30% uracil, and 10% cytosine
B. 40% cytosine, 20% adenine, and 30% uracil
C. 20% uracil, 40% cytosine, and 10% guanine
D. 20% thymine, 30% adenine, and 10% guanine
23
JANUARY 2002
Use the following information to answer the next question.
Serotonin stimulates the release of endorphins, and endorphins eventually cause the release of
more dopamine. Studies of individuals involved in extreme sports have found that these
people have lower-than-normal numbers of two of the five types of dopamine receptors.
—from Zorpette, 1999
54. The endorphin met-enkephalin is comprised of the amino acids methionine,
phenylalanine, glycine, glycine, and tyrosine. Possible mRNA codons for the
production of met-enkephalin are
A. ATG TTT GGT GGT TAT
B. ATG TTG GGC GGC TAT
C. AUG UUC GGT GGT UAC
D. AUG UUU GGC GGC UAC
Use the following information to answer the next question.
Most autosomal trisomies are lethal. The average survival age for infants with Patau
syndrome (trisomy 13) is six months. Infants with Edward syndrome (trisomy 18) survive, on
average, only two to four months. Individuals with Down syndrome (trisomy 21) can survive
into adulthood. In order to identify autosomal trisomies, chorionic villus sampling (CVS) can
be used to obtain cells that are then used to create a karyotype like the one shown below.
24
55. The sex and the condition of the individual whose karyotype is shown above are
given in row
Row
A.
B.
C.
D.
Sex
female
female
male
male
Condition
Patau syndrome
Down syndrome
Edward syndrome
normal
56. Mitochondrial DNA and nuclear DNA both code for the formation of proteins. Which
of the following statements about protein synthesis is true?
A. An mRNA anticodon binds with an amino acid codon, which results in the
placement of a specific tRNA molecule in the polypeptide chain.
B. An mRNA anticodon binds with a tRNA codon, which results in the placement of
a specific polypeptide molecule in the amino acid chain.
C. A tRNA anticodon binds with an mRNA codon, which results in the
placement of a specific amino acid molecule in the polypeptide chain.
D. A tRNA anticodon binds with a polypeptide codon, which results in the
placement of a specific mRNA molecule in the amino acid chain.
Use the following information to answer the next question.
In an individual with KSS, part of the coding strand of mitochondrial DNA that has
been deleted has the following base sequence.
ACC TCC CTC ACC AAA
57. The third amino acid coded for by this segment of mitochondrial DNA is
A. lysine
B. threonine
C. glutamate
D. phenylalanine
Use the following additional information to answer the next question.
Over time, mitochondrial DNA accumulates non-lethal mutations at a constant rate. There is
a higher degree of variation in mitochondrial DNA in earlier populations than in more recent
populations. Scientists have taken samples of mitochondrial DNA from people living on
different continents and compared the number of mitochondrial DNA mutations in these
samples. They used this data as evidence to determine the order in which Earth’s continents
were populated.
58. In this study, the manipulated variable was the
A. amount of mitochondrial DNA tested
B. time of migration from one continent to another
C. amount of variation in mitochondrial DNA base sequences
D. geographic location of subjects whose sample of mitochondrial DNA was tested
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Use the following additional information to answer the next two questions.
59. The row below that identifies process 1 and process 2 is
Row
A.
B.
C.
D.
Process 1
mitosis
mitosis
meiosis
meiosis
Process 2
meiosis
mitosis
mitosis
meiosis
60. The row below that identifies the chromosome number at the first stage and the
chromosome number at the second stage is
Row
A.
B.
C.
D.
First Stage
diploid
diploid
haploid
haploid
Second stage
haploid
diploid
diploid
haploid
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