Microbiology Exam 2 Practice Test Questions, Exams of Microbiology

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Elements that are required in relatively large amounts by microorganisms are called... A.multivitamins B. meganurtients C. macronutrients D. macromolecules - correct answers C. macronutrients 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 - correct answers A. hypotonic 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

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D. DNA and proteins E. DNa and phosophlipids - correct answers D. DNA and proteins Micooraginams that grow best at temperatures between 45-70 degrees celsius are called: A. Thermophiles B. Psycrophiles C. Thermophobes D. Mesophiles - correct answers A. Thermophiles 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 - correct answers B. determines the number of viable cells

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C. defined D. synthetic - correct answers B. Complex 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 - correct answers B. the length of time needed for a cell to divide 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 - correct answers C. a sequence of nucleotides in DNA that codes for a functional product How many nucleotide bases are found in the code for each amino acid?

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A. 2

B. 3

C. 4

D. varies with the paricular amino acid - correct answers B. 3 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 - correct answers D. both a selective and differential medium Which of the following is NOT a pyrimidine? A. adenine B. cytosine C. thymine

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C. tRNA D. mRNA - correct answers A. a new strand of DNA The site on the DNA to which a repressor protein binds is the ______ A. operon B. operator C. promotor D. regulator - correct answers B. operator 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 - correct answers C. substrate must be present and bind the repressor protein What enzyme makes cDNA from mRNA? - correct answers reverse transcriptase

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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 - correct answers A. the primary structure of the protein 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 - correct answers D. all of the above A transfer RNA (tRNA) carries... A. the mRNa transcript to the ribosome B. the proper amino acid C. the stop codon tot he ribosome

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A. lack exons B. lacks introns C. contains plasmid DNA D. does not requires a special enzyme - correct answers B. lacks introns 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 C. vector D. intron - correct answers C. 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 - correct answers B. clone

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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 - correct answers A. human DNA Genetic change in bacteria can be brought about by... A. nutation B. conjugation C. trasnduction D. transformation E. all of the answers are correct - correct answers E. all of the answers are correct Which of the following is NOT a desired characteristic of DNA vecotrs used in gene cloing procedures? A. self-replication

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D. site-directed mutagenesis. - correct answers C. PCR You have a small gene that you wish replicated by PCR. After 3 replicatin cyles, how many double-stranded DNA molecules do yo have? A. 2 B. 4 C. 8 D. 16 - correct answers C. 8 Which of the following cannot be infected by viruses? A. algae B. bacteria C. anaimals D. all of these can be infected by viruses - correct answers D. all of these can be infected my viruses Host specificity of a certain virus is determined by... A. reproductive stage of the virus. B. presence of surface spores.

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C. receptors found on the host cell. D. none of the above - correct answers C. receptors found on the host cell 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 - correct answers C. envelope 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 - correct answers A. retro virus A virus that infects bacteria is called... A. bacteriovirus B. bacteriophage

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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 - correct answers D. 8:45 pm 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 - correct answers A. nitrogen --- needed for amino acid synthesis High amounts of salt or sugar is often added to solution to preserve foods by creating a...

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A. depletion of nutrients B. hypotonic enviroment C. lower osmotic pressure D. hypertonic enviroment E. lower pH - correct answers D. hypertonic environment 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 - correct answers B. it cannot differentiate between live and dead cells 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

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C. adenine-uracil D. all of these are complementary base - correct answers D. all of these are complementary base 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 - correct answers C. semiconservative 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 - correct answers D. all of the above An enzyme that unwinds DNA strands so that each strand cal be replicated is...

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A. RNA polymerase B. DNA ligase C. DNA helicase D. DNA polymerase - correct answers C. DNA helicase 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 - correct answers B. trascription Te smallest genome would most likely be found in a... A. virus B. bacteria C. fungus D. human - correct answers A. virus Gene silencing in RNA interference blocks an undesirable product by...