Practice Exam 2 Questions Flashcards
Who first noticed the possible therapeutic properties of penicillin?
Alexander Fleming
Which of the following is the best definition of generation time?
The length of time is takes for a population of cells to double
An experiment began with 4 cells and ended with 128 cells. How many generations did the cell go through?
5
If you start out with a population density of 200 CFU/mL of a bacterium that divides every 20 minutes, what will the population density be at the end of two hours, assuming the cells are in the log phase of growth?
2^6 x 200 CFU/mL
Which of the following statements is true pertaining to the disk diffusion tests?
Clear zones around the colonies represent no growth in that particular area.
Which of the following is not an action of Penicillin?
Blocks the enzyme that catalyzes peptide chain elongation
Starvation proteins are produced by a culture during which portion of the growth curve?
Stationary Phase
This type of organism can live with or without oxygen, with no preference at all.
Facultative Anaerobe
A student noticed that a culture broth tube was very turbid at the bottom of the tube but completely clear at the top. What can they conclude about the organism?
The organism cannot produce SOD or catalase.
What kind of antibiotic is considered a “last resort” drug?
Vancomycin
Which is a false statement about microbial control methods?
Disinfectants can be used on human skin safely.
Which is true about moist heat?
Moist heat can destroy viruses and fungi.
What structures are used for protection against UV light and its harmful mutations?
Carotenoid pigments
Which is not a condition that influences the effectiveness of antimicrobial agents?
The linear relationship between concentration and effectiveness
Between antiseptics and disinfectants, which is considered more toxic?
Disinfectants
Select all the answers that are correct statements.
b. Waksman discovered the antibiotic streptomycin.
c. The minimum lethal concentration (MLC) is the lowest concentration of drugs from which organisms cannot recover when removed.
Which of the following is the best trait for an antibiotic to have?
Broad-spectrum, Bacteriostatic
Most bacterial and archaea cells divide using:
Binary Fission
In order for septation to fully take place, what needs to happen
The genetic material must replicate.
The Z ring must be assembled.
Chromosome partitioning must occur.
The higher the phenol coefficient value, then the _____ effective that the disinfectant is.
more
Which of the following units is considered an intermediate filament homologue?
CreS
Select all that apply about extremophiles and their characteristics
Halophiles prefer salt environments above 0.2 M NaCl.
Mesophiles can cause our flu-like symptoms.
How do Gram-negative organisms communicate in their biofilms?
Through autoinducer moleculesc.
Through acylhomoserine lactone
Which is not a possible reason for the stationary phase?
Programmed cell death or Apoptosis
Which of the following statements is false?
Counting chambers can distinguish living from dead cells due to its ability to count both eukaryotes and prokaryotes.
Which of the following is not a category of antimicrobial drugs?
Those that inhibit mRNA processing
Which of the following is used to grow bacterial cultures continuously (fresh medium added continuously)?
Chemostat
A bacterial population increases from 100 cells to 100,000,000 cells in 15 hours. What is the generation time of this culture?
45 minutes
Select all the answers that are true.
Bacteriophages are viruses that could target and lyse bacterial pathogens.
Tetracycline inhibits protein synthesis.
Folic acid can be used to synthesize nucleic acid subunits.
Which are characteristics of a continuous culture?
Continual removal of wastes
Maintaining cells in a constant stationary phase and biomass concentration
Constant supply of cells growing at a known rate
Which of the following is true about biofilm? Select all that apply.
Heterogeneity leads to increased interactions and communications among the bacterium.
Quorum sensing is responsible for the symbiosis between bacterium and bioluminescence in squids.e. Gram-positive bacteria use oligopeptides for quorum sensing.
Which of the following is not a reactive oxygen species?
Superoxide radical
Why are sulfa drugs that block folic acid considered highly selectively toxic?
Bacteria must synthesis folic acid, while humans acquire it from their diet.
Which antibacterial drug does not inhibit protein synthesis?
vancomycin
Cocktail drugs have decreased the onset of drug resistance in viruses.
true
Which method would best be used to remove microorganisms by physical screening?
Autoclaving
Why is dry heat less effective than moist heat?
It requires higher temperatures and longer exposure times.
Which of the following statements is true?
Thymine dimers prevent replication and transcription.
Which of the following antibiotics is considered a metabolic inhibitor?
Trimethoprim
Which is not a mechanism in which nucleic acid synthesis is inhibited?
Inhibition of transpeptidation
Which of the following is true about anti-fungal drugs?
Superficial mycoses can be treated topically and orally
Anti-HIV drugs can be:
Fusion inhibitors
Protease inhibitors
Which of the following statements is true about chromosome partitioning?
ParA works to pull a copy of the DNA away after depolymerization.
Which statement is true about antibiotics?
Aminoglycoside binds to the 30S subunit.
