Microbiology 154 Exam 2 Review Flashcards
Which kind of organism is killed by atmospheric oxygen?
a) facultative anaerobe
b) obligate aerobe
c) obligate anaerobe
d) aerotolerant anaerobe
c. obligate anaerobe
Toxic hydrogen peroxide produced in some bacteria can be broken down into water and oxygen by which enzyme?
a) superoxide dismutase
b) peroxidase
c) hydroxylase
d) catalase
d. catalase
Which of the following is not likely to be a reason for why exponential growth stops?
a) accumulation of waste products
b) exhaustion of nutrients
c) harmful changes in pH
d) bacteria becoming dormant
d. bacteria becoming dormant
In the stationary phase of growth in batch cultures
a) the number of microbial deaths exceeds the number of new cells formed
b) the number of microbial deaths is equal to the number of new cells formed
c) new cells are no longer formed because of adverse environmental conditions
d) cellular reproduction is most active
b. the number of microbial deaths is equal to the number of new cells formed
The removal or destruction of all microorganisms is called
a) sterilization
b) disinfection
c) pasteurization
d) sanitization
a. sterilization
If a population of 100,000 microbes has been treated with an antimicrobial chemical solution for two minutes and 90% of the population dies per minute, how many microbes remain after two minutes?
a) 100,000
b) 10,000
c) 1000
d) 100
c. 1000
The surface of your kitchen counter has 108 bacteria so you clean it with a disinfectant that kills 99.9% of germs on contact. How many bacteria remain and are viable?
a) 10^7
b) 10^6
c) 10^5
d) 10^4
c. 10^5
What is the process that turns on the transcription of a gene or genes?
a) induction
b) repression
c) translation
d) replication
a. induction
A segment of DNA that codes for a functional product is a(n)
e) genetic code
a) gene
b) codon
c) anticodon
a. gene
Transcription begins when RNA polymerase binds to the DNA at the
a) intron
b) start codon
c) terminator
d) promoter
d. promoter
An operon consists of
a) a set of genes that encode proteins in a particular pathway
b) a promotor
c) an operator site
d) all of the above (a-c)
e) none of the above (a-c)
d. all of the above(a-c)
The means to inhibit the metabolism of alternative carbon sources by glucose is called
a) induction
b) epigenetic control
c) corepression
d) catabolite repression
d. catabolite repression
In the lac operon of Escherichia coli an RNA polymerase
a) binds to the promotor region
b) carries out transcription of three structural genes needed to metabolize lactose
c) is blocked by a repressor protein bound to the operator region when glucose is present
d) all of the above
d. all of the above
Mutations
a) are a permanent change in the nucleotide sequence of DNA
b) may be neutral, beneficial, or harmful
c) can be spontaneous
d) all of the above
d. all of the above
Of the 64 codons, how many encode specific amino acids?
a) all 64 codons
b) just 61 codons
c) just 32 codons
d) just 20 codons
b. just 61 codons
The process in which bacteria pass their genes to other species of bacteria is known as
a) mitosis
b) vertical gene transfer
c) horizontal gene transfer
d) crossing over
b. vertical gene transfer
The process by which cells take up DNA from the surrounding environment is called
a) conjugation
b) protoplast fusion
c) transformation
d) microinjection
c. transformation
What kind of damage is caused to DNA by ultraviolet radiation?
a) insertions and deletions
b) thymine dimers
c) nitrogenous base substitutions
d) DNA strand breaks
b. thymine dimers
Mutations in which one nucleotide pair is deleted or inserted in the DNA are called
a) nonsense mutations
b) frameshift mutations
c) point mutations
d) base-pair mutations
b. frameshift mutation
If a restriction enzyme makes a staggered cut in DNA, then ________ ends are created.
a) flat
b) sticky
c) beveled
d) blunt
b. sticky
Restriction enzymes are naturally produced by and isolated from
a) bacteria
b) bacteriophages
c) human cells
d) plant cells
a. bacteria
You have one copy of a small gene that you wish to amplify by the polymerase chain reaction (PCR). After 5 replication cycles, how many double-stranded DNA molecules do you have?
a) 16
b) 32
c) 64
d) thousands
b. 32
Which of the following places the steps of PCR in the correct order?
(1) Incubate at 94°C to denature DNA strands;
(2) Incubate at 72°C for DNA synthesis;
(3) Incubate at 60°C for primer hybridization.
a) 1, 2, 3
b) 3, 2, 1
c) 1, 3, 2
d) 2, 1, 3
c. 1, 3, 2
Which enzyme would cut this segment of DNA? GCATGAGTTCGGATCCCAATGC CGTACTCAAGCCTAGGGTTACG (a) BamHI ↓ GGATCC CCTAGG ↑ (b) EcoRI ↓ GAATTC CTTAAG ↑ (c) HaeIII ↓ GGCC CCGG ↑
a. BamHI
Which of the following are environmental factors that influence microbial growth?
a) oxygen
b) temperature
c) osmotic pressure
d) kinds and concentrations of nutrients
e) all of the above
e. all of the above
Oxygen
a) required for strictly aerobic bacteria
b) can be toxic or lethal to some organisms
c) toxicity mostly due to the production of superoxide radicals that are powerful oxidizing agents
d) aerobic bacteria can protect themselves but strict anaerobes can not
e) all of the above
a. required for strictly aerobic bacteria ?
Generation time can best be defined as:
a) the length of time it takes for lag phase
b) the duration of log phase
c) the time it takes for a cell to divide
d) how many generations a cell can divide
c. the time it takes for a cell to divide
Starting with one bacterial cell, how many cells would you have after 10 generations?
a) 20
b) 40
c) 1024
d) 2048
c. 1024