Microbiology Exam 2 Practice Test 47 Questions with Verified Answers
Salts and sugars work to preserve foods by creating a
a. hypertonic
... [Show More] environment
b. hypotonic environment
c. lower pH
d. lower osmotic pressure
e. depletion of nutrients - CORRECT ANSWER a. hypertonic environment
The term facultative anaerobe refers to an organism that
a. uses oxygen or grows without oxygen
b. requires less oxygen than is present in air
c. is killed by oxygen
d. doesn't use oxygen but tolerates it - CORRECT ANSWER a. uses oxygen or grows without oxygen
Most bacteria grow best in pH
a. 1
b. 9
c. 7
d. 5
e. 14 - CORRECT ANSWER c. 7
A culture medium consisting of agar, human blood, and beef heart is a
a. complex medium
b. reducing medium
c. differential medium
d. selective medium
e. chemically defined medium - CORRECT ANSWER a. complex medium
Which of the following pairs is mismatched?
a. psychotroph - growth at 0C
b. mesophile - growth at 25C
c. thermophile - growth at 37C
d. psychophile - growth at 1C
e. none of the above - CORRECT ANSWER c. thermophile - growth at 37C
During which growth phase will gram-positive bacteria be most susceptible to penicillin?
a. stationary phase
b. lag phase
c. log phase
d. death phase
e. the culture is equally susceptible during all phases - CORRECT ANSWER c. log phase
Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?
a. thermophiles
b. halophiles
c. psychrophiles
d. anaerobes
e. none of the above - CORRECT ANSWER b. halophiles
This organism is killed by atmospheric O2
a. obligate anaerobe
b. aerobe
c. aerotolerant anerobe - CORRECT ANSWER a. obligate anaerobe
Bacterial death will result from danger to which of the following structures?
a. plasma membrane
b. nucleic acids
c. proteins
d. cell wall
e. all of the above - CORRECT ANSWER e. all of the above
Which of the following does not achieve sterilization?
a. formaldehyde
b. dry heat
c. ethylene oxide
d. pasteurization - CORRECT ANSWER d. pasteurization
Which of the following affects the elimination of bacteria from an object?
a. temperature
b. presence of organic matter
c. number of bacteria present
d. pH
e. all of the above - CORRECT ANSWER e. all of the above
Which of the following organisms can grow in 7% salt and spoil food?
a. E.coli
b. Staphylococcus aureus
c. viruses
d. streptococcus fecalis - CORRECT ANSWER b. Staphylococcus aureus
________ is added to make media solid
a. beef extra
b. agar
c. bolld
d. salt - CORRECT ANSWER b. agar
Boiling a solution for a few minutes may not kill ______?
a. amoeba
b. Bacterial endospores
c. E.coli
d. protozoa - CORRECT ANSWER b. Bacterial endospores
A heavy metal that can kill bacteria is?
a. copper
b. chlorine
c. iodine
d. sulfer - CORRECT ANSWER a. copper
True or false- Bacteria can grow fastest during their lag phase - CORRECT ANSWER False
Most human pathogens would be classified as _______?
a. psychophiles
b. thermophiles
c. Mesophiles
d. patofiles - CORRECT ANSWER c. Mesophiles
High osmotic pressure by salt or sugar removes water from cells. This is called?
a. Plasmolysis
b. cell rupture
c. hydrolysis
d. salting - CORRECT ANSWER a. Plasmolysis
50% of a bacteria cell is composed of _____?
a. nitrogen
b. DNA
c. carbon
d. water - CORRECT ANSWER c. carbon
Which of the following is a trace element?
a. carbon
b. iron
c. vitamin B
d. ATP - CORRECT ANSWER b. iron
What percent of bacteria from a natural sample is culturable?
a. 50%
b. 30%
c. 20%
d. 10% - CORRECT ANSWER d. 10%
Most bacteria reproduce by a process called?
a. fermentation
b. binary fission
c. binary fusion
d. transformation - CORRECT ANSWER b. binary fission
A chemical used to kill vegetative cells on living tissue is called?
a. Antiseptic
b. degermation
c. chlorine
d. disinfectant - CORRECT ANSWER a. Antiseptic
The best method to kill bacteria endospores is?
a. boiling
b. autoclaving
c. heatfixing
d. pasteuriztion - CORRECT ANSWER b. autoclaving
Pasteurization is often used in the production of?
a. can food
b. milk
c. jams
d. grass - CORRECT ANSWER milk
Which of these is a common halogen used to kill bacteria?
a. hydrogen
b. chlorine
c. sulfur
d. copper - CORRECT ANSWER chlorine
If a species contains 23% A in its DNA, what is the percentage of guanine it would contain?
a. 23%
b. 46%
c. 25%
d. 44%
e. 27% - CORRECT ANSWER e. 27%
The amount of adenine is always equal to the amount of
a. cytosine
b. uracil
c. guanine
d. thymine
e. ATP - CORRECT ANSWER
Which of the following statements about DNA replication is not correct
a. unwinding of the DNA molecule occurs as hydrogen bonds break
b. replication occurs as each base is paired with another exactly like it
c. the process is known as semiconservative replication because one old strand is conserved
in the new molecule
d. the enzyme that catalyzes DNA replication is DNA polymerase
e. complementary base pairs are held together with hydrogen bonds - CORRECT ANSWER b. replication occurs as each base is paired with another exactly like it
34. Because one original strand of the double stranded helix is found each daughter cell, the
replication process is called
a. proofreading
b. semiconservative
c. redundant
d. freeing of DNA
e. mutation positive - CORRECT ANSWER b. semiconservative
T or F - There are two kinds of nucleic acids, DNA and DNase - CORRECT ANSWER False
Which of the classes of RNA molecules carries the genetic information as it is needed for the
construction of a protein?
a. ribosomal RNA
b. transfer RNA
c. messenger RNA
d. primary mRNA transcript - CORRECT ANSWER c. messenger RNA
Which of the classes of RNA molecules carries the amino acids that are added to the
growing polypeptide chain?
a. ribosomal RNA
b. transfer RNA
c. messenger RNA
d. primary mRNA transcript - CORRECT ANSWER b. transfer RNA
Which of the classes of RNA molecules is linked with proteins in forming the large and small
subunits of cytoplasmic structure?
a. ribosomal RNA
b. transfer RNA
c. messenger RNA
d. primary mRNA transcript - CORRECT ANSWER a. ribosomal RNA
Prior to protein synthesis, the DNA
a. attracts tRNA's with appropriate amino acids
b. must first undergo replication
c. contains anticodons that must become codons
d. serves as a template for the production of mRNA
e. adheres to ribosomes for protein synthesis - CORRECT ANSWER d. serves as a template for the production of mRNA
Transcription of a part of DNA molecule with a nucleotide sequence of A-A-A-C-A-A-C-T-T
results in an mRNA molecule with the complementary
a. G-G-G-A-G-A-A-C-C
b. U-U-U-G-U-U-G-A-A
c. T-T-T-G-A-A-G-C-C
d. C-C-C-A-C-C-T-C-C - CORRECT ANSWER b. U-U-U-G-U-U-G-A-A
If one strand of DNA has the base sequence AAGCAA, the complentary strand has which of
the following sequences?
a. UUCGUU
b. TTCGTT
c. AAGCAA
d. UTCGTU
e. TTCGTG - CORRECT ANSWER b. TTCGTT
Which is the process that synthesizes mRNA, tRNA, or rRNA?
a. translation
b. transcription
c. transposition
d. transformation - CORRECT ANSWER b. transcription
Which of the following nucleotide bases is found only in RNA, not in DNA?
a. guanine
b. adenine
c. thymine
d. uracil
e. cytosine - CORRECT ANSWER d. uracil
Which of the following nucleotide bases is found only in DNA, not in RNA?
a. guanine
b. adenine
c. thymine
d. uracil
e. cytosine - CORRECT ANSWER c. thymine
Which of the process by which a protein is constructed?
a. translation
b. transcription
c. transposition
d. transformation - CORRECT ANSWER a. translation
Which of the following are involved in protein synthesis?
a. ribosomes
b. mRNA
c. tRNA
d. rRNA
e. all of the above - CORRECT ANSWER e. all of the above
Which compound is added to solidify bacteria growth media?
a. agar
b. gelatine
c. broth
d. blood - CORRECT ANSWER a. agar
The destruction of all forms of microbial life is called?
a. disinfection
b. sterilization
c. degermenation
d. sanitization - CORRECT ANSWER b. sterilization
Lysol contains?
a. phenol
b. alcohol
c. cloroz
d. halogens - CORRECT ANSWER a. phenol
T or F - Mixing chlorine with ammonia compounds can release toxic gas - CORRECT ANSWER False
Which of the following is NOT true about anaerobic respiration?
a. it generates ATP
b. it involves the Krebs cycle
c. it requires cytochromes
d. it involves glycolysis only
e. it involves the reduction of nitrate - CORRECT ANSWER d. it involves glycolysis only [Show Less]