Microbiology Q's-Set #1 Flashcards
What characteristic makes agar a useful culture medium?
a) it is liquid at room temperature
b) it is resistant to contamination by fungi
c) it cannot be digested by most microorganisms
d) it both melts and solidifies at 100deg.C*
c) it cannot be digested by most microorganisms
Who first used pure cultures to establish the cause of microbial diseases?
a) Robert Koch
b) Antonie van Leeuwenhoek
c) Joseph Lister
d) Louis Pasteur
a) Robert Koch
Which of the following contains LPS (lipopolysaccharides), which forms the basis of endotoxins?
a) both gram-positive and gram-negative cells
b) gram-positive cells
c) gram-negative cells
d) fungi
c) gram-negative cells
Bacilli can be described as having what shape?
a) spherical
b) spiral
c) spring
d) rod
d) rod
Which two bacteria genera are spore-forming?
a) Bacillus and Clostridium
b) Staphylococcus and Streptococcus
c) Neisseria and Mycobacteria
d) Escherichia and Salmonella
a) Bacillus and Clostridium
Which of the following describes a plasmid?
a) it is an extrachromosomal DNA for antibiotic resistance
b) it is a single-stranded extrachromosomal RNA for toxin resistance
c) it is an extrachromosomal DNA for heat resistance
d) it is a single-stranded DNA for dehydration resistance
a) it is an extrachromosomal DNA for antibiotic resistance
Which of the following bacterial structures is MOST involved in adherence?
a) capsule
b) lipopolysaccharide
c) ordinary pili
d) O-specific side-chain
c) ordinary pili
All of the following procedures are useful for the diagnosis of fungal infection EXCEPT which?
a) serology test
b) gram stain test
c) direct microscopic examination
d) culture fungi on Sabouraud’s agar
b) gram stain test
Why are gram-negative bacteria more resistant to antimicrobial agents (compared with gram-positive bacteria)?
a) the peptidoglycan layer in gram-negative bacteria is thicker
b) there is an outer membrane
c) all medically important gram-negative bacteria form endospores
d) a capsule forms a physical barrier in all gram-negative bacteria
b) there is an outer membrane
Which of the following stains is considered differential?
a) capsule stain
b) crystal violet
c) malachite green
d) acid-fast stain
d) acid fast stain
If a process kills 90% of the organisms per minute, how many minutes would it take to kill all organisms when starting with 10,000 organisms?
a) 5 minutes
b) 6 minutes
c) 4 minutes
d) 3 minutes
a) 5 minutes
Which of the following is a feature unique to prokaryotic cells?
a) they have a cell wall
b) they have circular DNA
c) they are unicellular organisms
d) they lack ribosomes
b) they have circular DNA
Koch’s postulates are used for which of the following purposes?
a) to determine if a given organism causes the given disease
b) to determine if the given organism is a bacterium or a fungus
c) to determine an organism’s growth requirements
d) to determine if a given organism will produce an immune response
a) to determine if a given organism causes the given disease
Why would a flagellated strain be more virulent than a nonflagellated strain?
a) flagella can kill the white blood cells
b) flagella allow the bacteria to negotiate in the mucus layers protecting body surfaces
c) flagella give metabolic advantage to the bacterium
d) flagella are major adhesive structures
b) flagella allow the bacteria to negotiate in the mucus layers protecting body surfaces
What is the type of virus replication where the virus remains dormant in the host cell called?
a) lytic cycle
b) lysogenic cycle
c) abortive infection
d) subclinical infection
b) lysogenic cycle
