Microbiology Exam #2 (Practice Test Questions). Real Exam Questions and Correct Answers, Exams of Microbiology

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Microbiology Exam #2 (Practice Test

Questions). Real Exam Questions and Correct

Verified Answers Updated 2024-2025. Graded

A

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

• ANSC. a sequence of nucleotides in DNA that codes for a functional product A piece of DNA that is self-replicating and used to carry desired genes into new cells is called a(n)... A. library B. clone

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

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...

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?

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

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 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