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Microbiology Exam #2 (Practice Test Questions). Real Exam Questions and Correct Verified Answers Updated 2024-2025. Graded A
Typology: Exams
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A culture medium consisting of agar, peptone, and beef heart, which are substances in which the amount of ingredients are unspecified, is a... A. chemically defined medium B. complex medium C. selective medium D. differential medium E. reducing medium - ANSB. complex medium A culture medium which only gram-positive organisms grow, and in which a yellow halo surrounds Staphylococcus aureus colinies, distinguishing S. aureus from other growing species, is best described as... A. a selective, but not differential medium
B. a differential, but not selective medium C. an enrichment culture D. both a selective a differential medium E. both a differential and enrichment culture - ANSD. both a selective and differential medium A gene is best defined as... A. a segment of DNA B. three nucleotides that code for an amino acid C. a sequence of nucleotides in DNA that codes for a functional product D. a sequence of nucleotides in RNA that codes for a functional product
C. vector D. intron - ANSC. vector A population of cells that are genetically identical and may be carrying a desired plasmid is called a(n)... A. genus B. clone C. vector D. intron - ANSB. clone A restriction enzyme is... A. a gene B. a segment of DNA C. a segment if mRNA D. a protein that catalyzes the cutting of DNA at specific sequences - ANSD. a protein that catalyzes the cutting of DNA at specifla sequences A transfer RNA (tRNA) carries...
A. the mRNa transcript to the ribosome B. the proper amino acid C. the stop codon tot he ribosome D. RNA polymerase to the ribosome - ANSB. the proper amino acid A virus that infects bacteria is called... A. bacteriovirus B. bacteriophage C. bactovirus D. bactophage - ANSB. bacteriophage An advantage of cDNA over genomic DNA for cloning genes eukayotes that are expressible in prokayotes is that it... A. lack exons B. lacks introns C. contains plasmid DNA D. does not requires a special enzyme - ANSB. lacks introns
An enzyme that unwinds DNA strands so that each strand cal be replicated is... A. RNA polymerase B. DNA ligase C. DNA helicase D. DNA polymerase - ANSC. DNA helicase At 4:00 pm a closed flask in inoculated with 1,000 cells. The lag phase lasts 1 hour. At 9:00 pm the culture enters stationary phase witha population of 65 million cells. The number of generation that have occurred is... A. 15 B. 16 C. 17 D. 18 - ANSB. 16 At 4:00 pm a closed flask is inoculated with 10,000 cells. The lag phase lasts 1 hour, At 9:00 pm the culture enters stationary phase with a
population of 65 million cells. At what time is the population half maximal? A. 6:30 pm B. 7:00 pm C. 8:30 pm D. 8:45 pm - ANSD. 8:45 pm Biotechnology involves the... A. use if microogansims to make anitbiotics B. the use of viruses to make vaccines C. ise of E. coli to produce human growth hormones D. all of the above - ANSD. all of the above Certain proteins, known is regulatory proteins, A. alre influenced by small molecules B. bind to specific DNA sites C. regulate transcription D. all of the above - ANSD. all of the above
Elements that are required in relatively large amounts by microorganisms are called... A.multivitamins B. meganurtients C. macronutrients D. macromolecules - ANSC. macronutrients Explain aerotolerant anaerobe - ANSorganisms that don't need oxygen, but can grow when present Explain facultative anaerobe - ANSorganisms that can survive without oxygen, but will use if present Explain how the replication of the viral genome in retroviruses unique among the viruses - ANSRNA ---> DNA through reverse transcriptase
Explain microaerophilic - ANSorganisms that require small amount of oxygen Explain obligate aerobe - ANSorganisms that need oxygen in order to grow Explain obligate anaerobe - ANSorganism that do not need oxygen in order to grow For the inducible lac operon to be turned on, the... A. lactase (enzyme) must not be excess. B. substrate (lactose) must be absent C. substrate must be present and bind the repressor protein D. RNA polymerase must be blocked from transcibing the genes - ANSC. substrate must be present and bind the repressor protein Gene silencing in RNA interference blocks an undesirable product by... A.blocking RNA polymerase from binding the DNA
B. binding siRNAs to mRNA transcripts, marking the mRNA for destruction C. blocking transcription C. blocking DNA replication - ANSB. binding siRNAs to mRNA transcripts, marking the mRNA for destruction Genetic change in bacteria can be brought about by... A. nutation B. conjugation C. trasnduction D. transformation E. all of the answers are correct - ANSE. all of the answers are correct High amounts of salt or sugar is often added to solution to preserve foods by creating a... A. depletion of nutrients B. hypotonic enviroment C. lower osmotic pressure
D. hypertonic enviroment E. lower pH - ANSD. hypertonic environment Host specificity of a certain virus is determined by... A. reproductive stage of the virus. B. presence of surface spores. C. receptors found on the host cell. D. none of the above - ANSC. receptors found on the host cell How many nucleotide bases are found in the code for each amino acid? A. 2 B. 3 C. 4 D. varies with the paricular amino acid - ANSB. 3 If an end compound reacts with the allosteric site of a previous enzyme, what would this indicate? A. mutation
B. repression C. feedback inhibition D. competitive inhibition - ANSC. feedback inhibition If cells are grown in media containing amino acids labeled with radioactive nitrogen, most of the radioactivity will be found in the cells... A. DNA B. proteins C. phospholipids D. DNA and proteins E. DNa and phosophlipids - ANSD. DNA and proteins If you knew the sequence of nucleotides within a gene, which on of the following could youdetermine with the most accuracy? A. the primary structure of the protein B. the secondary structure of the protein C. the tertiary strucutre of the protein
D. the quaternary structure of the protein E. the answer cannot be determined basedon on the information provided - ANSA. the primary structure of the protein Media counting some ingredients of unknown chemical composition are called ______ media A. undefined B. complex C. defined D. synthetic - ANSB. Complex Micooraginams that grow best at temperatures between 45-70 degrees celsius are called: A. Thermophiles B. Psycrophiles C. Thermophobes D. Mesophiles - ANSA. Thermophiles
Microorganisms that grow best at temperatures between -5 to 20 degrees celsius are know as... - ANSpsychrophiles One disadvantage of the direct microscopic count method of determining cell numbers os that: A. it is an indirect method B. it cannot differentiate between live and dead cells C. it can detect one viable cells D. the orifice gets clogges frequently - ANSB. it cannot differentiate between live and dead cells Self-replicating DNA vectors used to transmit a gene into an organism can include... A. plasmids B. viruses C. antigen D. both a and b - ANSD. both a and b
Synthesis of an enzyme coded by a repressible gene is stopped by the... A. transformation of the bacteria B. accumulation of product that the enzyme catalyzes the production of C. catabolism of the product D. RNa polymerase binding to the repressor - ANSB. accumulation of product that the enzyme catalyzes the production of Te smallest genome would most likely be found in a... A. virus B. bacteria C. fungus D. human - ANSA. virus The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA sunthesized would be most similar to... A. human DNA
B. T. aquaticus DNA C. both a and b D. human RNA E. T. aquaticus RNA - ANSA. human DNA The process in which RNA polymerase produces a segment of nuclei acids from the SNA template is called... A. DNA replication B. transcription C. translation D. redundant mutation - ANSB. trascription The processes of transcription and translate are coupled in... A. Eukaryotic cells B. prokaryotic cells C. both eukaryotic and prokaryotic cells D. neither eukaryotic nor prokaryotic - ANSB. prokaryotic cells
The site on the DNA to which a repressor protein binds is the ______ A. operon B. operator C. promotor D. regulator - ANSB. operator The total amount of living organisms is constant in the stationary phase because: A. there is a balance between cell growth and cell death B. there is a halt in cell division, even though the cells may remain metabolically active C. A or B can be correct D. niether A or B is correct - ANSC. A or B be correct The total number of viable microorganisms remains constant in stationary phase because: A. there is a balance between cell division and cell death
B. there is a cessation of cell division even though the cells may remain metabolically activie C. either a or b D. niether a or b - ANSC. either a or b Viruses are classified based on which of the following? A. nucleic acid content B. presence or absence of an envelope C. structure of capsid D. all of the above - ANSD. all of the above What are purines? - ANSAdenine and Guanine What are pyrimidines? - ANScytosine, thymine, uracil What enzyme makes cDNA from mRNA? - ANSreverse transcriptase What enzyme os required tp make cDNA from the mRNA?
A. splicase B. reverse transcritase C. helicase D. ligase - ANSB. reverse transcriptase What is cDNA? - ANScomplementary DNA; introns are spliced out What is the Avery-MacLeod-McCarty experiment? - ANSThe Griffith led to the Arthur McClout McCarthy experiment, and it discovered the transformaing principle of DNA What is the definition of a prophage? - ANSinactive viral genome that gets copied during cell division What occurs during transformation? - ANSDNA fragments are taken from dead cells
What of the following defines an inactive viral segment if nucleic acid inserted into a bacterial chromosome during a lysogenic cycle? A. retro virus B. prophage C. tmeperate phage D. transduction - ANSA. retro virus When a DNA molecule is replicated, the daughter molecules contain one strand of parental DNA and one strand of newly synthesized DNA; this is called ____ replication. A. semiconservative B. conservative C. semiconservative D. dispersive - ANSC. semiconservative When a microorganism is placed in a(n) ________ solution, water will eneter into the cell and cause it to burst unless something is done to prevent it.
A. hypotonic B. isotonic C. hypertonic D. osomotic - ANSA. hypotonic Which nitrogenous case would only be found in RNA? A. adenine B. thymine C. cytosine D. guanine E. uracil - ANSE. uracil Which of the following cannot be infected by viruses? A. algae B. bacteria C. anaimals D. all of these can be infected by viruses - ANSD. all of these can be infected my viruses
Which of the following elements is NOT correctly matched with its cellular function? A. nitrogen --- needed for amino acid synthesis B. phosphorus --- incorporated into nucleic acids C. sulfur --- used for disulfide bridges in proteins D. magnesium & potassium --- required as cofactors for some enzymes E. oxygen --- cell wasll and endospores stabilizer - ANSA. nitrogen --- needed for amino acid synthesis Which of the following in not found in all viruses? A. nucleiod acid B. protein coat C. envelope D. all of these are found in all viruses - ANSC. envelope Which of the following is a product of DNA replication? A. a new strant of DNa
B. rRNa C. tRNA D. mRNA - ANSA. a new strand of DNA Which of the following is a virus with a narrow host range, infecting human liver cells only? A. Poliovirus B. Hepatitus B C. Rabies D. Plasmodium - ANSB. Hepatitus B Which of the following is an advantage of the standard plate count? A. can readily count cells that fomr aggregates B. determines the number of viable cells C. can be performed on very dilute samples, such as lake water D. provides immediate results E. can be used to count heat-sensitive bacteria - ANSB. determines the number of viable cells
Which of the following is not a complementary base pair usually found in DNA molecules? A. adenine-thymine B guanine-cytosine C. adenine-uracil D. all of these are complementary base - ANSD. all of these are complementary base Which of the following is NOT a desired characteristic of DNA vecotrs used in gene cloing procedures? A. self-replication B. large size C. has a selctable marker D. circular form of DNA or integrates into the host chromosome E. may replicate in several species - ANSB. large size
Which of the following is NOT a direct method to measuree microbial growth? A. direct microscopic count B. standard plate count C. filtration on a support membrane followed by incubation on medium D. metabolic activity E. most probably number - ANSD. metabolic activity Which of the following is NOT a product of transcription? A. a new strand of DNA B. rRNA C. tRNA D. mRNA E. none of the ansers are correct; all of the are products of transciription - ANSA. a new strand of DNA Which of the following is NOT a pyrimidine? A. adenine
B. cytosine C. thymine D. uracil - ANSA. adenine Which of the following is the best definition of generation time? A. the length of time needed for lag phase B. the length of time needed for a cell to divide C. the minimum rate for 10 new cells to form D. the duration of exponential growth phase E. the timeneeded for nuclear division - ANSB. the length of time needed for a cell to divide Which of the following makes a molecule of DNA for a DNA template? A. DNA polymerase B. RNA polymerase C. helicase D. RNA primer - ANSA. DNA polymerase