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Bcor 11 Exam III
Question 1
Base-pair substitutions involving the third base of a codon are unlikely to result in an
error in the polypeptide. This is because
A) substitutions are corrected before transcription begins
B) substitutions are restricted to introns
C) the base-pairing rules are less strict for the third base of codons and
anticodons
D) a signal-recognition particle corrects coding errors
E) transcribed errors attract snRNPs, which then stimulate splicing and
correction
Questions 2-6
Please correctly match the discovery and the researchers responsible for them in the
following questions:
a. James Watson and Francis Crick
b. Fritz Miecher
c. Rosalind Franklin
d. Alfred Hershey and Martha Chase
e. Matthew Meselson and Franklin Stahl
Question 2
Used radioactive sulfur and phosphorus to trace the fate of protein and DNA in phages.
D
Question 3
Captured a clear photo of DNA using X-Ray diffraction.
C
Question 4
Isolated nuclein from white blood cells, later determined to be DNA.
B
Question 5
Described the structure of DNA as a double helix in a landmark 1953 Nature paper.
A
Question 6
Provided evidence for the semi-conservative hypothesis of DNA replication.
E
Question 7
When chromosomes convene on an imaginary plane that is equidistant between the
spindle’s two poles, this cell is said to be in what phase of the mitotic cycle?
A) telophase
B) prophase
C) anaphase
D) metaphase
E) prometaphase
Question 8
In a culture dish plated with mitotically active cells, a cell that has half as much DNA as
other cells is most likely in
A)
B)
C)
D)
E)
anaphase
prophase
metaphase
G1
G2
Question 9
What is the relationship among DNA, a gene, and a chromosome?
A) A chromosome contains hundreds of genes, which are composed of protein.
B) A chromosome contains hundreds of genes, which are composed of DNA.
C) A gene contains hundreds of chromosomes, which are composed of protein.
D) A gene is composed of DNA, but there is no relationship to a chromosome.
E) A gene contains hundreds of chromosomes, which are composed of DNA.
Question 10
Meiosis II is similar to mitosis in that
A) homologous chromosomes synapse
B) DNA replicates before the division
C) The daughter cells are diploid
D) Sister chromatids separate during anaphase
E) The chromosome number is reduced
Question 11
A part of an mRNA molecule with the following sequence is being read by a ribosome:
5' CCG-ACG 3' (mRNA). The following activated transfer RNA molecules are available.
Two of them can correctly match the mRNA so that a dipeptide can form.
The dipeptide that will form will be
A) cysteine-alanine.
B) proline-threonine.
C) glycine-cysteine.
D) alanine-alanine.
E) threonine-glycine.
tRNA Anticodon
Amino Acid
GGC
Proline
CGU
Alanine
UGC
Threonine
CCG
Glycine
ACG
Cysteine
CGG
Alanine
Question 12
Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism.
Approximately, what percentage of the nucleotides in this sample will be thymine?
A) 12
B) 24
C) 31
D) 38
E) It cannot be determined from the information provided.
Question 13
Which of the following statements is false when comparing prokaryotes with eukaryotes?
A) The prokaryotic chromosome is circular, whereas eukaryotic chromosomes
are linear.
B) Prokaryotic chromosomes have a single origin of replication, whereas
eukaryotic chromosomes have many.
C) The rate of elongation during DNA replication is higher in prokaryotes than in
eukaryotes.
D) Prokaryotes produce Okazaki fragments during DNA replication, but
eukaryotes do not.
E) Eukaryotes have telomeres, and prokaryotes do not.
Question 14
Which enzyme catalyzes the elongation of a DNA strand in the 5' 3' direction?
A) primase
B) DNA ligase
C) DNA polymerase
D) topoisomerase
E) helicase
Question 15
A space probe returns with a culture of a microorganism found on a distant planet.
Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in
15N medium for several generations and then transfer them to 14N medium. Which
pattern in Figure 16.1 would you expect if the DNA was replicated in a conservative
manner?
A.
B.
C.
D.
E.
Question 16
A particular triplet of bases in the coding sequence of DNA is AAA. The anticodon on the
tRNA that binds the mRNA codon is
A) TTT.
B) UUA.
C) UUU.
D) AAA.
E) either UAA or TAA, depending on first base wobble.
Question 17
The strands that make up DNA are antiparallel. This means that
A) the twisting nature of DNA creates nonparallel strands.
B) the 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the
other strand.
C) base pairings create unequal spacing between the two DNA strands.
D) one strand is positively charged and the other is negatively charged.
E) one strand contains only purines and the other contains only pyrimidines.
Question 18
The human X and Y chromosomes are
A) both present in every somatic cell of males and females alike.
B) of approximately equal size.
C) almost entirely homologous, despite their different names.
D) called "sex chromosomes" because they determine an individual's sex.
E) all of the above
Question 19
The Y-shaped structure where the DNA double helix is actively unwound during DNA
replication is called the
A) replication fork.
B) replication Y.
C) elongation junction.
D) unwinding point.
E) Y junction.
Question 20
A mutation results in a defective enzyme A in the pathway below. Which of the following
would be a consequence of that mutation?
Alpha
A)
B)
C)
D)
E)
A
Beta
B
Gamma
C
Delta
an accumulation of A and no production of B and C
an accumulation of A and B and no production of C
an accumulation of B and no production of A and C
an accumulation of B and C and no production of A
an accumulation of C and no production of A and B
Question 21
Which of the following is required only by eukaryotes for transcription?
A)
B)
C)
D)
E)
uracil
transcription factors
promoter
RNA polymerase
terminator
Question 22
Which of the following represents a similarity between RNA and DNA?
A) Both are double-stranded.
B) the presence of uracil
C) the presence of an OH group on the 2' carbon of the sugar
D) nucleotides consisting of a phosphate, sugar, and nitrogenous base
E) Both are found exclusively in the nucleus.
Question 23
Using RNA as a template for protein synthesis instead of translating proteins directly
from the DNA is advantageous for the cell because
A) RNA is much more stable than DNA.
B) RNA acts as an expendable copy of the genetic material, allowing the DNA to
serve as a permanent, pristine repository of the genetic material.
C) many mRNA molecules can be transcribed from a single gene, increasing the
potential rate of gene expression.
D) B and C only
E) A, B, and C
Question 24
If the liver cells of an animal have 24 chromosomes, how many chromosomes do its
sperm cells have?
A) 6
B) 12
C) 24
D) 48
E) 64
Question 25
A particular eukaryotic protein is 300 amino acids long. Which of the following could be
the maximum number of nucleotides in the DNA that codes for the amino acids in this
protein?
A) 3
B) 100
C) 300
D) 900
E) 1,800
Question 26
Which of these correctly illustrates the pairing of DNA and RNA nucleotides?
A) GTTACG with CAATCG
B) GTTACG with CAAUGC
C) GTTACG with GTTACG
D) GTTACG with ACCGTA
E) GTTACG with UAACAU
Question 27
What is the function of DNA polymerase?
A) to unwind the DNA helix during replication
B) to seal together the broken ends of DNA strands
C) to add nucleotides to the end of a growing DNA strand
D) to degrade damaged DNA molecules
E) to rejoin the two DNA strands (one new and one old) after replication
Question 28
Which of the following is true for both prokaryotic and eukaryotic gene expression?
A) After transcription, a 3' poly-A tail and a 5' cap are added to mRNA.
B) Translation of mRNA can begin before transcription is complete.
C) RNA polymerase binds to the promoter region to begin transcription.
D) mRNA is synthesized in the 3' → 5' direction.
E) The mRNA transcript is the exact complement of the gene from which it was
copied.
Question 29
Which of the following helps to stabilize mRNA by inhibiting its degradation?
A) TATA box
B) spliceosomes
C) 5' cap
D) poly-A tail
E) both C and D
Question 30
A mutant bacterial cell has a defective aminoacyl synthetase that attaches a lysine to
tRNAs with the anticodon AAA instead of a phenylalanine. The consequence of this for
the cell will be that
A) none of the proteins in the cell will contain phenylalanine.
B) proteins in the cell will include lysine instead of phenylalanine at amino acid
positions specified by the codon UUU.
C) the cell will compensate for the defect by attaching phenylalanine to tRNAs
with lysine-specifying anticodons.
D) the ribosome will skip a codon every time a UUU is encountered.
E) None of the above will occur; the cell will recognize the error and destroy the
tRNA.
Question 31
Once transcribed, eukaryotic mRNA typically undergoes substantial alteration that
includes
A) excision of introns.
B) fusion into circular forms known as plasmids.
C) linkage to histone molecules.
D) union with ribosomes.
E) fusion with other newly transcribed mRNA.
Question 32
A mutation in which of the following parts of a gene is likely to be most damaging to a
cell?
A) intron
B) exon
C) 5' UTR
D) 3' UTR
E) All would be equally damaging.
Question 33
What is an anticodon part of?
A) DNA
B) tRNA
C) mRNA
D) a ribosome
E) an activating enzyme
Question 34
Accuracy in the translation of mRNA into the primary structure of a protein depends on
specificity in the
A) binding of ribosomes to mRNA.
B) shape of the A and P sites of ribosomes.
C) bonding of the anticodon to the codon.
D) attachment of amino acids to tRNAs.
E) both C and D
Question 35
In animals, meiosis results in gametes, and fertilization results in
A) spores.
B) gametophytes.
C) zygotes.
D) sporophytes.
E) clones.
Question 36
The function of the ribosome in polypeptide synthesis is to
A) hold mRNA and tRNAs together.
B) catalyze the addition of amino acids from tRNAs to the growing polypeptide
chain.
C) move along the mRNA and eject tRNAs during the translocation process.
D) A and B only
E) A, B, and C
Question 37
Choose the answer that has these events of protein synthesis in the proper sequence.
1. An aminoacyl-tRNA binds to the A site.
2. A peptide bond forms between the new amino acid and a polypeptide chain.
3. tRNA leaves the P site, and the P site remains vacant.
4. A small ribosomal subunit binds with mRNA.
5. tRNA translocates to the P site.
A) 1, 3, 2, 4, 5
B) 4, 1, 2, 5, 3
C) 5, 4, 3, 2, 1
D) 4, 1, 3, 2, 5
E) 2, 4, 5, 1, 3
Question 38
Which of the following terms belongs with the words synapsis, tetrads, and chiasmata?
A) haploid
B) crossing over
C) autosomes
D) prophase II
E) fertilization
Question 39
What are polyribosomes?
A) groups of ribosomes reading a single mRNA simultaneously
B) ribosomes containing more than two subunits
C) multiple copies of ribosomes associated with giant chromosomes
D) aggregations of vesicles containing ribosomal RNA
E) ribosomes associated with more than one tRNA
Question 40
Which of the following is the term for a human cell that contains 22 pairs of autosomes
and two X chromosomes?
A) an unfertilized egg cell
B) a sperm cell
C) a male somatic cell
D) a female somatic cell
E) both A and D
Question 41-42
Each of the following is a modification of the sentence THECATATETHERAT.
A.
B.
C.
D.
E.
THERATATETHECAT
THETACATETHERAT
THECATARETHERAT
THECATATTHERAT
CATATETHERAT
Question 41
Which of the above is analogous to a frameshift mutation? D
Question 42
Which of the above is analogous to a single substitution mutation? C
Question 43
Sickle-cell disease is probably the result of which kind of mutation?
A) point
B) frameshift
C) nonsense
D) nondisjunction
E) both B and D
Question 44
At the end of ________ and cytokinesis, diploid cells form that are genetically identical to
the parent cell.
A) metaphase II
B) telophase I
C) telophase
D) telophase II
E) interphase
Question 45
Transcription occurs in
A) the cytoplasm.
B) a lysosome.
C) the nucleus.
D) a mitochondrion.
E) a nucleoplasm.
Question 46
During translation, chain elongation continues until what happens?
A) No further amino acids are needed by the cell.
B) All tRNAs are empty.
C) The polypeptide is long enough.
D) A stop codon is encountered.
E) The ribosomes run off the end of mRNA.
Question 47
In animals, somatic cells are produced by mitosis and ________ are produced by
meiosis.
A) gametes
B) clones
C) zygotes
D) spores
E) diploid cells
Question 48
Which of the following happens at the conclusion of meiosis I?
A) Homologous chromosomes are separated.
B) The chromosome number is conserved.
C) Sister chromatids are separated.
D) Four daughter cells are formed.
E) The sperm cells elongate to form a head and a tail end.
Question 49
DNA is replicated during this phase of the cell cycle
A)
B)
C)
D)
E)
G0
M
G1
G2
S
Question 50
A eukaryotic cell lacking telomerase would
A) produce Okazaki fragments
B) undergo a reduction in chromosome length
C) be highly sensitive to sunlight
D) be unable to replicate
E) have a high probability of becoming cancerous
Question 51
When comparing prophase I of meiosis with prophase of mitosis, which of the following
occurs only in meiosis?
A) The chromosomes condense.
B) Tetrads form.
C) The nuclear envelope disassembles.
D) A spindle forms.
E) Each chromosome is composed of two chromatids.
Questions 52-54
Refer to the images below and answer the following questions.
D
C
A
B
Question 52
Which diagram represents metaphase?
A) A
B) B
C) C
D) D
Question 53
Which drawing represents anaphase of mitosis?
A) A
B) B
C) C
D) D
Question 54
Which drawing represents prophase?
A) A
B) B
C) C
D) D