WorksheetsMicrobiology
Total questions: 15
Worksheet time: 27mins
You isolate a pure culture and determine that its characteristic are as follows. It grows optimally at 20°C. It will survive at temperatures from -15°C to +30°C. Its pH optimum for growth is 7.2. It was originally isolated on the surface of strawberry jam. You might correctly conclude that this microbe is a(n) __________.
mesophilic aerobe that resists plasmolysis when the water activity is low.
psychrophilic anaerobe that exhibits osmotic shock when the water activity is high.
thermophilic aerobe that resists plasmoptysis when the water activity is low.
psychrophilic aerobe that resists plasmolysis when the water activity is low.
Assume that Staphylococcus aureus grows on nutrient agar with up to and including 15% (w/v) NaCl, while Escherichia coli cannot grow on nutrient agar with more than 10% (w/v) NaCl. What does this mean?
NaCl at any concentration kills all types of bacteria.
NaCl at any concentration promotes the growth of all types of bacteria.
NaCl at 15% (w/v) concentration promotes the growth of all types of bacteria.
Some kinds of bacteria can grow at higher concentrations of NaCl than others.
Which one of the following statements about the affect of cold temperature is true?
Cold temperatures preserve microbes; the colder the temperature, the longer the preservation.
When cold temperatures kill cells, it is usually because the cold causes denaturation of critical cell proteins such as enzymes.
Refrigeration and freezing are effective methods of preserving food because it kills the microbes that cause food spoilage.
Most microbes have optimum growth temperatures below 20°C.
A chemical agent that kills the microorganisms and is commonly applied to substances used on inanimate objects are _______________
Antiseptics
Sanitizer
Disinfectants
Antibiotics
You are working with a type of bacterium that has a generation time of 30 minutes. You transfer cells from an exponentially growing culture to a fresh source of the same medium (assume no lag phase) so that the freshly inoculated medium contains 3.2 x 106 cells per milliliter. This new culture does not exhibit a lag phase. About how many cells (per milliliter) should you have after 1.5 hours incubation?
2.56 x 107
1.28 x 107
4.8 x 107
3.2 x 107
The decimal reduction time refers to the amount of time it takes to
reduce a microbial population by 10%
reduce a microbial population by 0.1%
reduce a microbial population by 90%
completely eliminate a microbial population
Identify the test to determine whether disinfectant solutions in a clinical setting are being used correctly.
disk-diffusion assay
phenol coefficient test
in-use test
use-dilution test
In the Kirby-Bauer disk diffusion test, the _______ of the zone of inhibition is measured and used for interpretation.
diameter
microbial population
number of colony
depth
Which of the following is the reason jams and dried meats often do not require refrigeration to prevent spoilage?
low pH
toxic alkaline chemicals
naturally occurring antibiotics
low water activity
Ali discovers a soil bacterium and able to produce an antimicrobial that kills gram-negative bacteria. He isolates and purifies the antimicrobial compound, then chemically converts a chemical side chain to a hydroxyl group. This new version of antimicrobial drug can now also kill gram-positive bacteria. The new antimicrobial drug with broad-spectrum activity is considered to be which of the following?
resistant
semisynthetic
synthetic
natural
Identify which combinations would most likely contribute to the development of a superinfection ?
long-term use of narrow-spectrum antimicrobials
long-term use of broad-spectrum antimicrobials
short-term use of narrow-spectrum antimicrobials
short-term use of broad-spectrum antimicrobials
Which of the following resistance mechanisms describes the function of β-lactamase?
efflux pump
target mimicry
drug inactivation
target overproduction
Followings are the correct combination of drug and its mechanism of action except
Polyenes: binds to and disrupt the fungal cell membrane
Griseofulvin: blocks intracellular microtubules
Allylamines: inhibits spread of virus to new cells
Flucytosine: inhibition RNA synthesis
Describe the 4 mechanisms of antibiotic resistance
List the 4 groups of beta lactam antibiotics
