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WorksheetsBCBIO23-LAB CA
Total questions: 20
Worksheet time: 10mins
The cells synthesize RNA, growth factors and other molecules required for cell division.
Lag Phase
Log Phase
Stationary Phase
Death Phase
This phase is marked by the doubling of the bacterial cells.
Lag Phase
Log Phase
Stationary Phase
Death Phase
The cell population remains constant at this stage. Plotting this phase on the graph gives a smooth horizontal linear line.
Lag Phase
Log Phase
Stationary Phase
Death Phase
This is the last phase of the bacterial growth.
Lag Phase
Log Phase
Stationary Phase
Death Phase
What is the typical wavelength used to measure bacterial growth in a spectrophotometer?
200 nm
260 nm
600 nm
800 nm
The Kirby-Bauer method is used to assess antibiotic sensitivity. What is the key indicator of antibiotic effectiveness?
Zone of inhibition
Increase in colony count
Change in color of the agar plate
pH variation
Why is it important to use a control plate when testing antibiotic sensitivity?
To ensure uniform bacterial growth
To check for contamination
To compare growth in the absence of antibiotics
All of the above
What is the role of ethidium bromide in agarose gel electrophoresis?
To break down DNA
To stain DNA for visualization under UV light
To increase the migration speed of DNA
To degrade proteins
Why is loading dye added to DNA samples before running gel electrophoresis?
To increase the density of the sample
To visualize DNA bands
To enhance DNA degradation
To cut DNA into smaller fragments
If two bands appear for the same plasmid DNA sample after gel electrophoresis, what does it indicate?
Presence of RNA contamination
Degradation of DNA
Different conformations of plasmid DNA (supercoiled and relaxed)
Presence of genomic DNA contamination
What factor influences the migration speed of DNA in an agarose gel?
Size of DNA fragments
Strength of electric field
Concentration of agarose
All of the above
If no plaques are observed after incubation in a bacteriophage isolation experiment, what could be the reason?
No bacteriophages were present in the sample
The bacterial strain used was resistant to infection
The incubation conditions were not optimal
All of the above
Which method is commonly used to isolate bacteriophages from environmental samples?
Agar dilution method
Soft agar overlay method
Gram staining
PCR analysis
Bacteriophages are viruses that specifically infect:
Fungi
Bacteria
Plants
Animals
The zone of inhibition in antibiotic-producing bacteria is due to:
Nutrient consumption
Antibiotic diffusion
Mutation in bacterial genes
Increased oxygen concentration
What is the function of chloroform in bacteriophage isolation?
It enhances phage adsorption
It lyses bacterial cells to release phages
It stains phages for visualization
It acts as a pH buffer
What do plaques represent in a bacteriophage isolation experiment?
Bacterial contamination
Areas where phages have lysed bacteria
Dead phages
Bacterial colonies
Which of the following conditions can affect plaque size in a bacteriophage experiment?
All of the above
Host bacterial strain
Agar concentration
Incubation time
A zone of inhibition for penicillin against Staphylococcus aureus is measured to be 22 mm. If the required zone for susceptibility is ≥18 mm, is the bacteria susceptible or resistant?
Susceptible
Resistant
Intermediate
Cannot determine
You inoculate 10 mL of bacterial culture into 90 mL of fresh medium. What is the dilution factor?
1:5
1:10
1:50
1:100
