Microbiology Exam 2 practice Tests 208 Questions with Verified Answers
Which of the following statements is correct?
A) For every amino acid, there
... [Show More] is one codon.
B) A codon may signify more than one amino acid.
C) For every codon, there is one amino acid.
D) All of these are correct. - CORRECT ANSWER For every Codon, there is one amino acid
The sigma factor of RNA polymerase is necessary for
A) maximum transcription of the gene.
B) termination of the mRNA chain.
C) elongation of the mRNA chain.
D) specific recognition of promoter elements. - CORRECT ANSWER Specific recognition of promoter elements
Highly specific molecular "scissors" that slice out sections of DNA are called:
A) DNA polymerase
B) Restriction enzymes
C) RNA polymerase
D) Nucleases - CORRECT ANSWER Restriction Enzymes
Calcium chloride and heat shock may be used in-vitro to induce what type of horizontal gene transfer?
A) transformation
B) transduction
C) conjugation
D) replicon - CORRECT ANSWER Transformation
Poultry products are a likely source of infection by
A) Shigella spp.
B) Helicobacter pyloris.
C) Salmonellaenterica.
D) Vibrio cholera. - CORRECT ANSWER Salmonellaenterica
Which enzyme "charges" a tRNA molecule with the appropriate amino acid?
A) tRNA ligase
B) Aminoacyl-tRNA synthetase
C) RNA polymerase
D) DNA polymerase - CORRECT ANSWER Aminoacyl- tRNA synthetase
Which of the following tests uses auxotrophs and liver extract to reveal potential mutagens?
A) Blue White Screening
B) Replica Plating
C) Plaque Assay
D) Ames - CORRECT ANSWER Ames
A prokaryotic mRNA transcript
A) must be transported from the nucleus before it is transcribed.
B) must be processed to remove the introns prior to translation.
C) must be released from the DNA when a stop codon is reached.
D) is ready to be translated as soon as it is transcribed. - CORRECT ANSWER Is ready to be translated as soon as it is transcribed
During DNA sequencing,
A) DNA fragments migrate through a gel and a DNA probe is added .
B) radioactive nucleotides are attached to the "old" DNA prior to separation by electrophoresis.
C) dideoxynucleotides tagged with four different fluorescent dyes are employed.
D) the DNA to be analyzed is "chopped" into fragments prior to being mixed with new nucleotides. - CORRECT ANSWER Dideoxynucleotides tagged with four different fluorescent dyes are employed
You have isolated a gram negative rod from a urine that is a lactose fermenter and indole positive. Which of the following is the most likely identification?
A) Escherichia coli
B) Serratia marcescens
C) Enterobacter
D) Proteus mirabilis - CORRECT ANSWER Escherichia coli
What ingredients are required for PCR?
A) DNA, nucleotides, DNA polymerase, primers
B) primers, DNA, restriction enzymes, plasmids
C) chromosomes, DNA polymerase, amino acids
D) plasmids, nucleotides, primers, chromosomes - CORRECT ANSWER DNA, nucleotides, DNA polymerase, primers
Which of the following bacteria has decreased incidence because of a vaccine and requires factors X and V (heme and NAD+) for its growth?
A) Salmonella
B) Bordetella
C) Haemophilus
D) Shigella - CORRECT ANSWER Haemophilus
The initial tRNA carrying the formylmethionine enters the ribosomal ___ site.
A) R
B) A
C) P
D) E - CORRECT ANSWER P
Successful insertion of a DNA fragment into the polylinker region of a plasmid vector is detected by
A) production of the enzyme β-galactosidase and growth of blue colonies.
B) production of the enzyme β-galactosidase and growth of white colonies.
C) absence of the enzyme β-galactosidase and growth of blue colonies.
D) absence of the enzyme β-galactosidase and growth of white colonies. - CORRECT ANSWER Absence of the enzyme B- galactosidase and growth of white colonies
The function of a ribosome is
A) to process pre-mRNAs into mature mRNAs.
B) to hold mRNA and tRNAs in the correct positions to enable translation.
C) to attach amino acids onto the appropriate tRNAs.
D) to make more mRNA. - CORRECT ANSWER To hold mRNA and tRNAs in the correct positions to enable translation
What is the role of tRNA in translation?
A) It catalyzes peptidyl transferase activity.
B) It brings together two subunits of a ribosome.
C) It helps fold up the finished polypeptide chain.
D) It binds to an mRNA codon and carries the corresponding amino acid. - CORRECT ANSWER It binds to an mRNA codon and carries the corresponding amino acid
Which of the following is mismatched?
A) Mycoplasma pneumonia - walking pneumonia
B) Campylobacter jejuni - peptic ulcers
C) Treponema pallidum - syphilis
D) Borrelia burgdorferi - Lyme disease - CORRECT ANSWER Campylobacter jejuni- peptic ulcers
All of the following are true of the tryptophan operon except:
A) excess tryptophan turns operon on
B) tryptophan acts as a corepressor
C) RNA polymerase binds to the promoter
D) operon is normally on - CORRECT ANSWER Excess tryptophan turns operon on
Many bacteria are naturally capable of taking up endogenous fragments of DNA in their environment, a phenomenon termed
A) transformation.
B) transfection.
C) hybridization.
D) conjugation. - CORRECT ANSWER Transformation
The reaction catalyzed by reverse transcriptase.
A) mRNA → protein
B) DNA → mRNA
C) DNA → DNA
D) mRNA → cDNA - CORRECT ANSWER mRNA --> cDNA
Certain strains of Escherichia coli produce enterotoxins that are carried on
A) insertion sequences
B) bacteriocin plasmids
C) virulence plasmids
D) R plasmids - CORRECT ANSWER Virulence plasmids
Which of the following is unculturable and the VDRL test is done to screen for antibodies against the causative agent?
A) Treponema
B) Neisseria gonorrhoeae
C) Chlamydia
D) Haemophilus - CORRECT ANSWER Treponema
In order to make crops such as corn and cotton resistant to certain insect pests, scientist insert the gene for
A) beta carotene
B) Bt toxin
C) HGH
D) Roundup resistance - CORRECT ANSWER Bt toxin
Petechiae and DIC are complications of
A) Shigellosis
B) Hemolytic Uremic Syndrome
C) Pertussis
D) Meningococcemia - CORRECT ANSWER Meningococcemia
According to the CDC's FoodNet, which of the following bacteria is responsible for the most common bacterial gastroenteritis in New York State?
A) E. coli O157
B) Campylobacter jejuni
C) Vibrio cholerae
D) Listeria monocytogenes - CORRECT ANSWER Campylobacter jejuni
In PCR, what is the function of the primers?
A) They separate DNA strands.
B) They extract DNA from cells.
C) They are the enzymes that replicate DNA.
D) They indicate where DNA synthesis should start. - CORRECT ANSWER They indicate where DNA synthesis should start
Isolation of which of the following organisms indicates severe lung dysfunction in cystic fibrosis patients?
A) Legionella pneumophila
B) Mycoplasma pneumonia
C) Burkholderia cepacia
D) Pseudomonas aeruginosa - CORRECT ANSWER Burkholderia cepacia
In prokaryotic cells, termination of transcription sometimes requires
A) transcription factors
B) Rho protein
C) a stop codon
D) sigma factor - CORRECT ANSWER Rho Protein
A mutation causes a G to be inserted after the first base of the codon for tryptophan. How will this affect the growing polypeptide chain?
A) The reading frame will be shifted to the left, and the wrong amino acids will be added from this point on.
B) Elongation will stop prematurely.
C) It will not be affected.
D) There will be a single amino acid substitution. - CORRECT ANSWER The reading frame will be shifted to the left and the wrong amino acids will be added from this point on
The first successful treatment of a human genetic disorder through gene therapy was with a disorder known as
A) human dwarfism.
B) hemophilia.
C) diabetes mellitus.
D) severe immunodeficiency disease (ADA). - CORRECT ANSWER Severe immunodeficiency disease (ADA)
A eukaryote used in genetic engineering is
A) Pseudomonas.
B) Bacillus thuringiensis.
C) Saccharomyces cerevisiae.
D) Agrobacterium tumefaciens. - CORRECT ANSWER Saccharomyces cerevisiae
Which of the following molecular techniques employs silicon chips with single stranded DNA affixed in precise locations?
A) PCR
B) DNA Sequencing
C) Southern Blot
D) DNA microarray - CORRECT ANSWER DNA microarray
As helicase unwinds the DNA molecule, what keeps the strands apart?
A) DNA polymerase
B) Okazaki fragments
C) Reverse transcriptase
D) Single-strand binding proteins - CORRECT ANSWER Single-strand binding proteins
Given the following DNA strand, what amino acid sequence will be produced? DNA: TAC CGA TCA GAT
A) methionine -valine -glycine -leucine
B) methionine -leucine -tyrosine - arginine
C) methionine -lysine - serine -histidine
D) methionine -alanine -serine -leucine - CORRECT ANSWER Methionine- alanine- serine- leucine
Which of the following microbes produces a protein that kills a variety of insect pests?
A) Bacillus thuringiensis
B) Pseudomonas
C) Thermus aquaticus
D) Haemophilus influenzae - CORRECT ANSWER Bacillus thuringiensis
If the codon AAA is changed to AAG, it still codes for the amino acid lysine; this is an example of a
A) nonsense mutation.
B) missense mutation.
C) frameshift mutation.
D) silent mutation. - CORRECT ANSWER Silent mutation
Which of the following must be removed from an mRNA molecule before it can be translated in eukaryotes?
A) anticodon
B) exon
C) intron
D) codon - CORRECT ANSWER Intron
The etiological agent of Lyme Disease is ________________________ and is transmitted to humans by a __________________.
Treponema pallidum; mosquito
Borrelia burgdorferi; tick
Treponema pallidum; tick
Borrelia burgdorferi; mosquito - CORRECT ANSWER Borrelia burgdorferi; tick
Which of the following causes mutations by creating thymine dimers?
A) nucleotide analogs
B) ethidium bromide
C) gamma rays
D) ultraviolet light - CORRECT ANSWER Ultraviolet light
Which of the following is found at the 5' end of a DNA strand?
A) a hydroxyl group
B) a methyl group
C) histones
D) a phosphate group - CORRECT ANSWER A phosphate group
All of the following are associated with prokaryotic genomes except:
A) one chromosome (rarely two).
B) circular chromosomes.
C) histones.
D) no nuclear membrane. - CORRECT ANSWER Histones
All of the following are characteristics of Okazaki fragments except:
A) They make up the leading strand of replicated DNA.
B) They are checked for accuracy by DNA polymerase.
C) They are joined together by DNA ligase.
D) They begin with an RNA primer. - CORRECT ANSWER They make up the leading strand of replicated DNA
If all the following DNA fragments were analyzed on an electrophoresis gel, which one would migrate farthest from the wells?
A) 5,000 basepairs
B) 2,500 basepairs
C) 250 basepairs
D) 750 basepairs - CORRECT ANSWER 250 basepairs
Culture 1: F+, leucine+, histidine+
Culture 2: F-, leucine-, histidine-
In Table 7, what will be the result of conjugation between cultures 1 and 2?
A) 1 will remain the same; 2 will become F+, leu+, his+
B) 1 will remain the same; 2 will become F+, leu-, his-
C) 1 will become F-, leu-, his-; 2 will remain the same
D) 1 will become F-, leu+, his+; 2 will become F+, leu-, his- - CORRECT ANSWER 1 will remain the same; 2 will become F+, leu-, his-
Culture 1: F+, leucine+, histidine+
Culture 2: F-, leucine-, histidine-
A) They will both remain the same
B) 1 will become F-, leu+, his+; 2 will become F-, leu+, his+
C) 1 will become F-, leu-, his-; 2 will become F+, leu-, his-
D) 1 will remain the same; 2 will become F-, leu+, his+ - CORRECT ANSWER 1 will remain the same; 2 will become F-, leu+, his+
All of the following are components of a nucleotide EXCEPT _____________.
A. A phosphate group
B. A pentose sugar
C. An amino group
D. A nitrogenous base - CORRECT ANSWER An amino group
Which of the following statements concerning the structure of DNA is FALSE?
A. The two strands of a DNA molecule are antiparallel to each other
B. DNA contains the nitrogenous bases A, C, G, and U
C. DNA contains the sugar deoxyribose
D. The two strands of DNA molecules are held together by hydrogen bonds - CORRECT ANSWER DNA contains the nitrogenous bases A, C, G, and U
Which of the following statements concerning RNA is FALSE?
A. It provides energy for cells
B. It serves as a structural component of ribosomes
C. It catalyzes protein synthesis
D. It can consist of codons and anticodons - CORRECT ANSWER It provides energy for cells
All of the following are associated with the nucleus of a eukaryotic cell EXCEPT ___________.
A. Chromatin
B. DNA
C. Ribosomes
D. Histones - CORRECT ANSWER Ribosomes
Ribosomes __________.
A. Are composed of three subunits
B. Contain three mRNA binding sites
C. Are responsible for nucleic acid synthesis in a cell
D. Are different in eukaryotic and prokaryotic cells - CORRECT ANSWER Are different in eukaryotic and prokaryotic cells
The amino acid sequence of a protein constitutes its _________.
A. Quaternary structure
B. Primary structure
C. Secondary structure
D. Tertiary structure - CORRECT ANSWER Primary structure
Which of the following is NOT a monomer?
A. Amino Acids
B. Monosaccharides
C. Deoxyribonucleic Acid
C. Fatty Acids - CORRECT ANSWER Deoxyribonucleic Acid
The transfer of DNA between bacterial cells is often facilitated by which of the following?
A. A ribosome
B. A pilus
C. Fimbriae
D. A Flagellum - CORRECT ANSWER A pilus
All of the following are possible base pair combinations in nucleic acids EXCEPT ___________.
A. A-T
B. A-U
C. G-C
D. C-T - CORRECT ANSWER C-T
The chromosomes of prokaryotic cells can be found in its _____________.
A. Inclusions
B. Nucleus
C. Nucleoid
D. Endoplasmic Reticulum - CORRECT ANSWER Nucleoid
In taxonomy, a strain is a more specialized subset of which of the following?
A. A class
B. A family
C. A genus
D. A species - CORRECT ANSWER A Species
Cultures that are visible on the surface of a solid growth medium are known as __________.
A. Colonies
B. CFUs
C. Inocula
D. Slants - CORRECT ANSWER Colonies
Pyrimidines are molecules used in the synthesis of which of the following?
A. Carbohydrates
B. Proteins
C. Nucleic Acids
D. Lipids - CORRECT ANSWER Nucleic Acids
Radiation causes DNA mutations by ____________.
A. Breaking covalent bonds between the sugars and phosphates of DNA
B. Producing Ions
C. Producing thymine dimers
D. Performing all of these actions - CORRECT ANSWER Performing all of these actions
Transcription and translation are what type of metabolic pathways?
A. Catabolic
B. Metabolic
C. Amphibolic
D. Anabolic - CORRECT ANSWER Anabolic
Lactose induces gene expression in the lac operon by binding which molecule?
A. Operator
B. Repressor
C. RNA Polymerase
D. Catabolic Activator Protein (CAP) - CORRECT ANSWER Repressor
The central dogma of genetics consists of _________.
A. Transcription and translation
B. DNA replication, transcription, and translation
C. Transcription and DNA replication
D. DNA replication and translation - CORRECT ANSWER Transcription and translation
Quorum sensing is a bacterial phenomenon related to the presence of which of the following?
A. Biofilms
B. Inclusions
C. The cell wall
D. The cell membrane - CORRECT ANSWER Biofilms
How many amino acids are used by cells to make proteins?
A. 15
B. 21
C. 25
D. 64 - CORRECT ANSWER 21
In which of the following locations in a eukaryotic cell would we NOT find DNA molecules?
A. Nucleus
B. Golgi body
C. Mitochondria
D. Chloroplasts - CORRECT ANSWER Golgi Body
Which of the following is most likely the number of base pairs in a bacterial chromosome?
A. 4,000,000
B. 4000
C. 400
D. 40 - CORRECT ANSWER 4,000,000
Which of the following is a true statement concerning prokaryotic chromosomes?
A. They typically have two or three origins of replication
B. They contain single-stranded DNA
C. They are located in the cytosol
D. They are associated in linear pairs - CORRECT ANSWER They are located in the cytosol
A Plasmid is ____________.
A. A molecule of RNA found in bacterial cells
B. Distinguished from a chromosome by being circular
C. A structure in bacterial cells formed from plasma membrane
D. Extrachromosomal DNA - CORRECT ANSWER Extrachromosomal DNA
Which of the following forms ionic bonds with eukaryotic DNA and stabilizes it?
A. Chromatin
B. Bacteriocin
C. Histone
D. Nucleoid - CORRECT ANSWER Histone
Nucleotides used in the replication of DNA __________.
A. Carry energy
B. Are found in four forms, each with a deoxyribose sugar, a phosphate and a base
C. Are present in cells as triphosphate nucleotides
D. All of the above - CORRECT ANSWER All of the above
Which of the following molecules functions as a "proofreader" for newly replicated stands of DNA?
A. DNA polymerase III
B. Primase
C. Helicase
D. Ligase - CORRECT ANSWER DNA polymerase III
The addition of -CH3 to a cytosine nucleotide after DNA replication is called _________.
A. Methylation
B. Restriction
C. Transcription
D. Transversion - CORRECT ANSWER Methylation
Translation, the site through which tRNA molecules leave a ribosome is called the ________.
A. A site
B. X site
C. P site
D. E site - CORRECT ANSWER E site
The Ames test ____________.
A. Uses auxotrophs and liver extract to reveal mutagens
B. Is time intensive and costly
C. Involves the isolation of a mutant by eliminating wild-type phenotypes with specific media
D. Proves that suspected chemicals are carcinogenic - CORRECT ANSWER Uses auxotrophs and liver extract to reveal mutagens
Which of the following methods of DNA repair involves enzymes that recognize and correct nucleotide errors in unmethylated strands of DNA?
A. Light repair of T dimers
B. Dark repair of P dimers
C. Mismatch repair
D. SOS response - CORRECT ANSWER Mismatch repair
Which of the following is not a mechanism of natural genetic transfer and recombination?
A. transduction
B. Transformation
C. Transcription
D. Conjugation - CORRECT ANSWER Transcription
Cells that have the ability to take up DNA from their environment are said to be _________.
HFR cells
Transposing
Genomic
Competent - CORRECT ANSWER Competent
Which of the following statements is true?
A. Conjugation requires a sex pilus extending from the surface of a cell
B. Conjugation requires a C factor
C. Conjugation is an artificial genetic engineering technique
D. Conjugation involves DNA that has been released into the environment - CORRECT ANSWER Conjugation requires a sex pilus extending from the surface of the cell
Which of the following are called "Jumping Genes"?
A. HRF cells
B. Transducing phages
C. Palindromic sequences
D. Transposons - CORRECT ANSWER Transposons
Although two cells are totally unrelated, one cell receives DNA from the other cell and incorporates this new DNA into its chromosome. This process is _________.
A. Crossing over of DNA from the two cells
B. Vertical gene transfer
C. Horizontal gene transfer
D. Transposition - CORRECT ANSWER Horizontal Gene Transfer
Transcription produces __________.
A. DNA molecules
B. RNA molecules
C. Polypeptides
D. Palindromes - CORRECT ANSWER RNA molecules
A nucleotide is composed of _____________.
A. A five-carbon sugar
B. Phosphate
C. A nitrogenous base
D. All of the above - CORRECT ANSWER All of the above
In DNA, adenine forms _____ hydrogen bonds with ________.
A. Three; Uracil
B. Two; Uracil
C. Two; thymine
D. Three; thymine - CORRECT ANSWER Two; thymine
A sequence of nucleotides formed during replication of the lagging strand is___________
A. A palindrome
B. An okazaki fragment
C. A template strand
D. An operon - CORRECT ANSWER An okazaki fragment
Which of the following is not part of the operon?
A. Operator
B. Promoter
C. Origin
D. Gene - CORRECT ANSWER Origin
Repressible operons are important in regulating prokaryotic _________.
A. DNA replication
B. RNA transcription
C. rRNA processing
D. Sugar catabolism - CORRECT ANSWER RNA transcription
Which of the following is part of each molecule of mRNA?
A. Palindrome
B. Codon
C. Anticodon
D. Base pair - CORRECT ANSWER Codon
Ligase plays a major role in _________.
A. Lagging strand replication
B. mRNA processing in eukaryotes
C. Polypeptide synthesis in ribosomes
D. RNA transcription - CORRECT ANSWER Lagging strand replication
Before mutations can affect a population permanently, they must be ____________.
A. Lasting
B. Inheritable
C. Beneficial
D. All of the above - CORRECT ANSWER All of the above
The trp operon is repressible. This means it is usually _______ and is directly controlled by __________.
A. active; an inducer
B. active; a repressor
C. inactive; an inducer
D. inactive; a repressor - CORRECT ANSWER active; a repressor
Which of the following statements is true concerning recombinant DNA technology?
A. It will replace biotechnology in the future
B. It is a single technique for genetic manipulation
C. It is useful in manipulating genotypes but not phenotypes
D. It involves modification of an organism's genome - CORRECT ANSWER It involves modification of an organism's genome
A DNA gene synthesized from an RNA template is ___________.
A. Reverse transcriptase
B. Complementary DNA
C. Recombinant DNA
D. Probe DNA - CORRECT ANSWER Complementary DNA
After scientists exposed cultures of Penicillium to agents X, Y, and Z, they examined the type and amount of penicillin produced by the altered fungi to find the one that is most effective. Agents X, Y, and Z were probably ___________.
A. Recombinant Cells
B. Competent
C. Mutagens
D. Phages - CORRECT ANSWER Competent
Which of the following is false concerning vectors in recombinant DNA technology?
A. Vectors are small enough to manipulate outside a cell
B. Vectors contain a recognizable genetic marker
C. Vectors survive inside cells
D. Vectors must contain genes for self- replication - CORRECT ANSWER Vectors must contain genes for self- replication [Show Less]