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Multiple Choice Quiz
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1
Only cells in the digestive system have genes for digestive enzymes.
A)True
B)False
2
The control of gene expression is of major importance to the health of all species.
A)True
B)False
3
The _____ model proposed by Jacob and Monod explains gene regulation in prokaryotes.
A)endosymbiotic
B)cohesion-tension
C)operon
D)fluid mosaic
4
Which of the following is part of an operon?
A)promoter
B)operator
C)structural genes
D)all of the above
5
A regulator gene is located _____ the operon.
A)outside
B)inside
6
If an active repressor is bound to the operator RNA polymerase cannot attach to the promoter and transcription does not occur.
A)True
B)False
7
The short sequence of DNA where RNA polymerase first attaches when a gene is to be transcribed is called the _____.
A)promoter
B)operator
C)A site
D)replication fork
8
The repressor that controls whether the operon is active or not is coded for by ____.
A)a structural gene
B)an intron
C)a regulator gene
D)the promoter
9
Repressible operons are usually involved in metabolic pathways that break down a nutrient.
A)True
B)False
10
The trp operon is a _____ operon since the presence of tryptophan turns off the operon.
A)inducible
B)repressible
11
When E. coli is denied glucose and given lactose instead, it immediately begins to make _____.
A)enzymes for lactose metabolism
B)enzymes for sucrose metabolism
C)enzymes for galactose metabolism
D)all of the above
12
When glucose is absent and lactose is present, lactose binds to the operon's repressor which makes it unable to bind to the _____.
A)structural genes
B)operator
C)promotor
D)none of the above
13
Tryptophan is called the _____ because its presence turns off the trp operon.
A)corepressor
B)inducer
14
Genes can be switched on or off in each particular type of cell.
A)True
B)False
15
Inducible operons are ordinarily turned off.
A)True
B)False
16
The lac operon _____.
A)is turned on in the presence of lactose
B)is an inducible operon
C)has three structural genes in it
D)all of the above
17
The enzymes produced by the lac operon are needed only when lactose is present.
A)True
B)False
18
The structural genes of the trp operon produce _____.
A)enzymes for the metabolism of lactose
B)enzymes for the synthesis of lactose
C)enzymes for the metabolism of tryptophan
D)enzymes for the synthesis of tryptophan
19
The lac operon is only maximally active when glucose is absent and lactose is present.
A)True
B)False
20
If glucose and lactose are present the cell preferentially metabolizes _____.
A)glucose
B)lactose
21
When glucose is absent _____
A)the lactose operon is turned off
B)cyclic AMP decreases
C)RNA polymerase is better able to bind to the lac operon promoter
D)all of the above
22
The lac operon's promoter is better exposed to RNA polymerase when _____ binds to the DNA next to lac promoter.
A)ATP
B)glucose
C)a catabolic activator protein
D)tryptophan
23
Cells rely only on negative control of their operons.
A)True
B)False
24
When glucose is present _____.
A)there is little cAMP in the cell
B)CAP is inactive
C)the lactose operon does not function maximally
D)all of the above
25
Gene regulation in prokaryotic cells generally occurs at the transcription level.
A)True
B)False
26
Jumping genes were discovered by _____.
A)Friedrich Miescher
B)Barbara McClintock
C)Rosalind Franklin
D)James Watson
27
There is/are _____ level(s) of control of gene expression in eukaryotes.
A)one
B)two
C)three
D)four
28
In the nucleus of the eukaryote __________ control takes place.
A)transcriptional
B)translational
C)posttranscriptional
D)both A and C
29
After DNA is transcribed and preliminary mRNA is formed _____ control occurs in the nucleus.
A)transcriptional
B)posttranscriptional
C)translational
D)all of the above
30
In the cytoplasm there is _____ control of gene expression.
A)posttranscriptional
B)translational
C)posttranslational
D)both B and C
31
Changes that the polypeptide must experience before it is biologically functional are a part of _____ control of gene expression.
A)transcriptional
B)posttranscriptional
C)translational
D)posttranslational
32
The life expectancy of the mRNA affects the _____ control of gene expression.
A)transcriptional
B)posttranscriptional
C)translational
D)posttranslational
33
Differential processing of the primary mRNA and the speed with which the mature mRNA leaves the nucleus affects the _____ control of gene expression.
A)transcriptional
B)posttranscriptional
C)translational
D)posttranslational
34
The rate at which structural genes are transcribed in a eukaryotic cell does not change.
A)True
B)False
35
Once a polypeptide has been produced there is no control over its function.
A)True
B)False
36
mRNA can be chemically altered which will affect the specific protein produced by the cell.
A)True
B)False
37
The amount of protein produced depends on _____.
A)how long it takes mRNA to leave the nucleus
B)how long mRNA remains active in the cytoplasm
C)both A and B
38
Lightly stained areas of chromatin are called _____ and are believed to be genetically active.
A)heterochromatin
B)euchromatin
39
A condensed, inactive X chromosome is referred to as _____.
A)a telomere
B)euchromatin
C)a Barr body
D)a transposon
40
Histones can _____ genes.
A)repress
B)activate
C)both A and B
41
The amino acid sequences of the histone proteins vary little between organisms suggesting that there have been few mutations in the histone proteins during the course of evolution.
A)True
B)False
42
Barr bodies cause the bodies of heterozygous females to be mosaic with patches of genetically different cells.
A)True
B)False
43
Varying the amount of chromatin as in polytene chromosomes is another form of _____ control.
A)transcriptional
B)posttranscriptional
C)translational
D)posttranslational
44
Lampbrush chromosomes in vertebrates and polytene chromosomal puffs in insects are examples of genetically active, less compacted _____.
A)euchromatin
B)heterochromatin
45
Transcription factors must bind to _____ before transcription begins in a eukaryotic cell.
A)a promoter
B)enhancers
C)both A and B
46
During mRNA processing differential excision of _____ and splicing of mRNA can vary the type of mRNA that leaves the nucleus.
A)exons
B)introns
47
Even after ejection of their nucleus mature mammalian red blood cells are able to synthesize hemoglobin due to the presence of the necessary mRNA's persistence.
A)True
B)False
48
The length of time a mature mRNA transcript remains active may be determined by _____.
A)the presence of different hormones
B)differences in the guanine nucleotide cap at the 5' end of the mRNA
C)differences in the poly-A tail at the 3' end of the mRNA
D)all of the above
49
Most metabolic pathways are regulated by feedback inhibition which is a form of posttranslational control.
A)True
B)False
50
Geneticists now believe transposons can _____.
A)cause localized mutations
B)be a source of chromosome mutations such as translocations, deletions and inversions
C)can contain one or more genes that may convey antibiotic resistance to a bacterium
D)all of the above
51
Which of these can be mutagens?
A)UV radiation
B)organic chemicals in tobacco smoke
C)X-rays
D)all of the above
52
Spontaneous mutations due to DNA replication errors are very rare.
A)True
B)False
53
Very few spontaneous mutations occur during DNA replication because of the proofreading done by _____.
A)helicase
B)RNA polymerase
C)DNA ligase
D)DNA polymerase
54
The raw material for evolution comes from _____ mutations.
A)germ-line
B)somatic
55
Somatic mutations are not passed to the next generation.
A)True
B)False
56
Genetic mutations always adversely affect the organism in which they occur.
A)True
B)False
57
Smoking is implicated in the development of cancer of the _____.
A)lung
B)bladder
C)larynx
D)all of the above
58
Thymine dimers are caused by _____.
A)UV radiation
B)X-rays
C)organic chemicals in tobacco smoke
D)all of the above
59
When alcohol consumption is combined with smoking the risk of developing cancer increases.
A)True
B)False
60
Thymine dimers _____.
A)form when two thymine molecules next to each other bond together
B)cannot be repaired once they occur
C)are associated with a lower incidence of skin cancer
D)all of the above
61
Specific DNA sequences that are able to move within and between chromosomes are called _____.
A)oncogenes
B)transposons
C)operons
D)telomeres
62
The movement of a transposon to a new location can increase the expression of a neighboring gene.
A)True
B)False
63
Which of the following is caused by a transposon?
A)the white-eye mutant in Drosophila
B)phenylketonuria
C)sickle-cell disease
D)none of the above
64
Cancer cells _____.
A)are fully differentiated cells
B)divide a finite number of times
C)lack contact inhibition
D)all of the above
65
The prevention of cancer may be accomplished by _____.
A)high-fiber foods
B)eating more fruits and vegetables
C)less sunbathing
D)all of the above
66
Oncogenes _____.
A)may code for a faulty receptor
B)stimulate uncontrolled cell growth
C)may produce an abnormal protein product
D)all of the above
67
A mutation of a proto-oncogene can cause it to become an oncogene, a cancer causing gene.
A)True
B)False
68
A growth factor is a signaling protein responsible for the mutation of genes.
A)True
B)False
69
The passage of cells through the cell cycle is promoted by _____.
A)structural genes
B)proto-oncogenes
C)a regulator gene
D)tumor-suppressor genes
70
The oncogenes most frequently involved in human cancers belong to the ras gene family.
A)True
B)False
71
The most frequently mutated tumor-suppressor gene in human cancers is the _____.
A)rasK oncogene
B)RB gene
C)p53 gene
D)BRCA1 gene
72
There is/are _____ type(s) of regulatory pathways that extend from the plasma membrane to the nucleus.
A)one
B)two
C)three
D)four
73
When growth-inhibitory factors bind plasma membrane receptors _____.
A)the stimulatory pathway is activated
B)proto-oncogenes stimulate the cell cycle
C)tumor-suppressor genes inhibit the cell cycle
D)all of the above
74
A change in a single DNA nucleotide _____.
A)may have no effect on the individual
B)is called a frameshift mutation
C)always results in a non-functional protein
D)all of the above
75
A point mutation is the cause of sickle-cell disease.
A)True
B)False
76
Nonfunctional proteins are responsible for _____.
A)cystic fibrosis
B)phenylketonuria
C)androgen insensitivity
D)all of the above
77
A completely new sequence of codons results from a _____ mutation.
A)point
B)frameshift
78
Frameshift mutations occur when one or more nucleotides are _____ into/from the DNA.
A)inserted
B)deleted
C)both A and B
79
A change in a single DNA nucleotide is called a _____ mutation.
A)point
B)frameshift
80
If a point mutation occurs midway through the DNA code for a protein and a stop codon results, the protein will _____.
A)function normally
B)be incomplete
C)have a different sequence of amino acids





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