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Biology & Life Science
Q:
In prokaryotes, most of the control of gene expression is at the ____ level.
a. transcriptional
b. transcript processing
c. transport
d. translational
e. post-translational
Q:
The obvious advantage of the lactose operon is that
a. it allows bacteria to survive in the presence of lactose.
b. lactose-metabolizing enzymes need not be made when lactose is not present.
c. it enables bacteria to make lactose only in the presence of the proper enzymes.
d. it negates the need for milk in the diet of adult humans.
e. it enables glucose to substitute for lactose in the diet of lactose intolerant persons.
Q:
Repressor proteins
a. prevent binding of RNA polymerase to DNA.
b. cause the DNA regions that contain the operator to twist or loop.
c. inactivate operon genes when their products are not required.
d. bind to sets of operators.
e. do all of these.
Q:
Mutation of the C group gene in Arabidopsis thaliana produces flowers that
a. are sterile.
b. have no carpels.
c. have no stamens.
d. have a profusion of petals.
e. are all of these.
Q:
Mutation of the B group gene in Arabidopsis thaliana affects development in its flower's
a. first whorl only.
b. second whorl only.
c. third whorl only.
d. first and second whorls.
e. second and third whorls.
Q:
Mutation of the A group gene in Arabidopsis thaliana affects development in its flower's
a. first whorl only.
b. second whorl only.
c. third whorl only.
d. first and second whorls.
e. second and third whorls.
Q:
In the ABC model of flower development in Arabidopsis thaliana, sepals form when gene(s) ____ is(are) switched on.
a. A
b. A and B
c. B and C
d. C
e. A and B and C
Q:
Which of the following statements is false concerning X chromosome inactivation?a. It is an accident of evolution.b. It is an example of dosage compensation.c. It is a gene control mechanism.d. Normal development of female embryos depends on it.e. It does not occur in males.
Q:
The mosaic effect of X inactivation in human females can be observed in
a. skin color.
b. hair color.
c. fingernails.
d. distribution of sweat glands.
e. all of these.
Q:
A mammalian female's
a. cells usually have multiple Barr bodies.
b. body is a mosaic for the X-linked traits she inherits.
c. Barr bodies are active in some cells.
d. Barr bodies are produced after puberty.
e. X-linked recessive genes are always expressed because of the deactivation of an X chromosome in each cell.
Q:
X chromosome inactivation results in the
a. total inactivation of both X chromosomes.
b. inactivation of only the paternal X chromosome.
c. inactivation of only the maternal X chromosome.
d. inactivation of either the paternal X chromosome or the maternal X chromosome.
e. nonrandom inactivation of X chromosomes in the initial cells of tissues.
Q:
Genes located in cells in different regions of the body during embryonic development may
a. be turned on and off.
b. never be turned on.
c. be turned on and left on.
d. be activated for only a short time in one cell and a long time in another cell.
e. do all of these.
Q:
The products of genes that are switched on in specific tissues at specific stages of development affect mainly
a. gene replication.
b. gene transcription.
c. mRNA transcript processing.
d. translation.
e. post-translational processing of proteins.
Q:
What are the odds of a given cell division producing a product with a mutation in a region that produces a protein product?
Q:
What does the fact that all organisms use essentially the same genetic code suggest about the origin of life?
Q:
Assume alternative splicing can generate all permutations and combination. How many proteins could a gene with three exons and two introns generate?
Q:
The concepts of transcription and translation have been said to form the "central dogma" of molecular biology. Is this a fitting description?
Q:
Mutations may arise by replication error, __________ activity, or exposure to environmental hazards.
Q:
Genetic information carried by a(n) __________ directs the synthesis of a __________ chain during translation.
Q:
Each tRNA has an __________ that base-pairs with a codon, and each binds to the kind of amino acid specified by the codon.
Q:
In transcription, RNA polymerase binds to a __________ in the DNA near a gene, and then assembles a strand of RNA.
Q:
Gene expression requires the participation of the following three types of RNA: __________, __________and __________.
Q:
The process of gene expression includes two steps: __________ and __________.
Q:
You will need a genetic code table to answer the following. The following statements refer to the five RNA codons listed below; match them appropriately.
a. AUG
b. UAA
c. UUU
d. UUA
e. AAA
This codon codes for an amino acid and indicates the beginning of a coding region.
Q:
You will need a genetic code table to answer the following. The following statements refer to the five RNA codons listed below; match them appropriately.
a. AUG
b. UAA
c. UUU
d. UUA
e. AAA
A DNA codon of ATT is complementary to this RNA codon.
Q:
You will need a genetic code table to answer the following. The following statements refer to the five RNA codons listed below; match them appropriately.
a. AUG
b. UAA
c. UUU
d. UUA
e. AAA
A single mutation involving the second letter of codon AUA could convert it to this codon.
Q:
You will need a genetic code table to answer the following. The following statements refer to the five RNA codons listed below; match them appropriately.
a. AUG
b. UAA
c. UUU
d. UUA
e. AAA
The anticodon AAA pairs with this codon.
Q:
You will need a genetic code table to answer the following. The following statements refer to the five RNA codons listed below; match them appropriately.
a. AUG
b. UAA
c. UUU
d. UUA
e. AAA
This codon terminates a coding region.
Q:
Translation
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Transcription
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Promoters
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Polysome
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Messenger RNA
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Nirenberg, Leder
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Codon
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
McClintock
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
Anticodon
Choose the best matching element.
a. deciphered the mRNA code words
b. RNA-directed synthesis of polypeptide chains
c. sites at which RNA polymerases can bind and initiate transcription
d. binds to small subunit platform of a ribosome
e. guided and catalyzed by RNA polymerases
f. polypeptide chain elongation proceeds independently at each body in this cluster
g. discovered transposons
h. a tRNA triplet opposite a codon
i. a set of three nucleotides
Q:
The difference between normal and sickle-cell hemoglobin is based upon
a. the number of amino acids in the molecule.
b. the substitution of one amino acid for another.
c. the number and orientation of the amino acid chains attached to the heme portion of the molecule.
d. the number of oxygen molecules that can be carried.
e. the type of bone marrow that produces it.
Q:
Frameshift mutations may involve
a. substitution of nucleotides.
b. substitution of codons.
c. substitution of amino acids.
d. addition or deletion of one or more base pairs.
e. none of these.
Q:
Mutations can be
a. random.
b. beneficial.
c. lethal.
d. heritable.
e. all of these.
Q:
Which event may occur in all viruses, prokaryotes, and eukaryotes?
a. duplication
b. aneuploidy
c. translocation
d. mutation
e. none of these
Q:
Which of the following statements is true?
a. Gene mutations occur independently of each other.
b. Gene mutations are relatively rare.
c. Ionizing radiation causes chromosomal damage and free radical formation.
d. Mutations are random; that is, it is impossible to predict exactly when a specific gene will mutate, but an expected frequency can be assigned.
e. All of these are true.
Q:
A gene mutation
a. is a change in the nucleotide sequence of DNA.
b. may be caused by environmental agents.
c. may arise spontaneously.
d. can occur in any organism.
e. is described by all of these.
Q:
Which stage of translation is shown in the figure above?
a. initiation
b. elongation
c. termination
d. peptide bond formation
e. polysome activity
Q:
Which event of translation is shown in the figure above?
a. initiation
b. elongation
c. termination
d. peptide bond formation
e. elongation and peptide bond formation
Q:
A polysome is
a. one of the units of a ribosome.
b. the nuclear organelle that synthesizes RNA.
c. an organelle that functions similarly to a ribosome during meiosis.
d. the two units of a ribosome considered together.
e. an mRNA molecule with several ribosomes attached.
Q:
During the termination stage
a. a STOP codon enters the ribosome.
b. release factors bind the ribosome.
c. mRNA detaches from the ribosome and the polypeptide chain.
d. ribosomal subunits separate.
e. all of these occur.
Q:
Which event occurs during the elongation stage?
a. Peptide bonds form.
b. Free amino acids bind to the mRNA binding site.
c. Anticodons bind to complementary codons.
d. A STOP codon enters the ribosome.
e. Peptide bonds form, and anticodons bind to complementary codons.
Q:
The structure in the above figure demonstrates which of the following?
a. transcription and translation occur simultaneously on a single strand
b. ribosomes attached to a strand of DNA
c. a small ribosomal subunit
d. multiple ribosomes on a strand of mRNA
e. all of these
Q:
In correct order, the three stages of translation are
a. initiation, replication, and termination.
b. elongation, peptide bond formation, and codon-anticodon pairing.
c. initiation, chain elongation, and termination.
d. termination, initiation, and replication.
e. none of these.
Q:
Ribosomal subunits
a. come together in threes to form functional units.
b. are composed of mRNA and structural proteins.
c. are synthesized in the cytoplasm.
d. converge only when mRNA is to be translated.
e. are transcribed from the complementary strand of DNA that is used for tRNA transcription.
Q:
The wobble effect pertains to the matching of
a. codons with anticodons.
b. codons with exons.
c. exons with introns.
d. template DNA with messenger RNA.
e. messenger RNA with ribosomal RNA.
Q:
Which of the following carries amino acids to ribosomes, where amino acids are linked into the primary structure of a polypeptide?
a. mRNA
b. tRNA
c. hnRNA
d. rRNA
e. all of these
Q:
If the DNA nucleotides read ATG-CGT-GAC, the amino acid sequence of the resulting polypeptide would bea. tyrosine - alanine - leucine.b. methionine - arginine - asparagines.c. histidine - glycine - praline.d. serine - lysine - glycine.e. all of these.
Q:
The following questions refer to the genetic code table above.AUGCGUCCAThe sequence of amino acids specified by this mRNA isa. serine - histidine - lysine.b. methionine - arginine - proline.c. methionine - alanine - serine.d. valine - arginine - leucine.e. none of these.
Q:
The following questions refer to the genetic code table above.
The first amino acid of a new polypeptide chain is
a. alanine.
b. cysteine.
c. variable.
d. phenylalanine.
e. methionine.
Q:
Of all the different codons that exist, three of them
a. are involved in mutations.
b. do not specify a particular amino acid.
c. cannot be copied.
d. provide instructions such as STOP.
e. do not specify a particular amino acid and provide instructions such as STOP.
Q:
There are how many different kinds of RNA codons?
a. 3
b. 12
c. 28
d. 64
e. 120
Q:
There are how many different kinds of amino acids in proteins?
a. 3
b. 6
c. 12
d. 20
e. 28
Q:
The genetic code is made up of units consisting of how many nucleotides?
a. 2
b. 3
c. 5
d. 6
e. 9
Q:
In this depiction of transcription, the ____ strand is ____ because it ____.
a. upper; RNA; is single-stranded.
b. lower; RNA; contains uracil.
c. lower; RNA; contains thymine.
d. upper; RNA; has no uracil (U).
e. lower; DNA; contains adenine (A).
Q:
If the DNA triplets are ATGï€CGT, the mRNA codons area. AUG-CGU.b. ATG-CGT.c. UAC-GCA.d. UAG-CGU.e. all of these.
Q:
Before messenger RNA is mature,
a. all exons are deleted and removed.
b. a cap and a tail are provided.
c. anticodons are assembled.
d. the transfer RNA transfers the messenger RNA to the ribosome.
e. the single RNA strand duplicates itself in much the same way as DNA.
Q:
The portion of the DNA molecule that is translated is composed of
a. introns.
b. anticodons.
c. exons.
d. transcriptions.
e. exons and transcriptions.
Q:
Which of the following dominates in the process of transcription?
a. RNA polymerase
b. DNA polymerase
c. helicase
d. transfer RNA
e. all of these dominate in the process of transcription
Q:
Transcription starts at a region of DNA called a(n)
a. sequencer.
b. promoter.
c. activator.
d. terminator.
e. transcriber.
Q:
The relationship between strands of RNA and DNA is
a. antagonistic.
b. opposite.
c. complementary.
d. an exact duplicate.
e. unrelated.
Q:
Uracil will pair witha. ribose.b. adenine.c. cytosine.d. thymine.e. guanine.
Q:
DNA and RNA are alike in
a. the pentose sugar.
b. all the nitrogenous bases used to assemble the genetic code.
c. the number of strands.
d. their function in genetics.
e. none of these.
Q:
The form of RNA that carries the code from DNA to the site of protein assembly is called
a. messenger RNA.
b. nuclear RNA.
c. ribosomal RNA.
d. transfer RNA.
e. structural RNA.
Q:
All of the different kinds of RNA are transcribed in the
a. mitochondria.
b. cytoplasm.
c. ribosomes.
d. nucleus.
e. endoplasmic reticulum.
Q:
____ molecules carry protein-assembly instructions from the nucleus to the cytoplasm.
a. Template DNA
b. Messenger RNA
c. Transfer RNA
d. Ribosomal RNA
e. All of these
Q:
The two steps of transcription followed by translation
a. explain the structural complexity of genes.
b. describe the flow of genetic information.
c. are based upon the role of proteins in controlling life.
d. do not explain how genes function.
e. explain evolution in terms of molecular biology.
Q:
The helix structure on the right of the above figure represents
a. DNA.
b. RNA.
c. lipid.
d. protein.
e. phospholipid.
Q:
A linear stretch of DNA that specifies the sequence of amino acids in a polypeptide is called a(n)
a. codon.
b. intron.
c. messenger.
d. gene.
e. enzyme.
Q:
Ricin is toxic because
a. it binds to eukaryotic DNA.
b. it binds to eukaryotic mRNA.
c. it blocks food from entering the cell.
d. it inactivates ribosomes.
e. it binds to nerve tissue and causes paralysis.
Q:
Ricin is
a. a substance found in castor bean seeds.
b. a polysaccharide extracted from rice.
c. an ingredient in many paints and cosmetics.
d. a protein that inactivates ribosomes.
e. a substance found in castor bean seeds and a protein that inactivates ribosomes.
Q:
Does reproductive cloning always involve somatic cell nuclear transfer?
Q:
Is it possible to prevent mutations entirely?
Q:
A bacterium undergoes four rounds of replication. How many cells would result, and how many of those cells would still have part of an original DNA strand from the starting bacterium ?