25 Questions
Which of the following is a characteristic that effects microbial growth?
Chemical and physical factors
What is the purpose of a dilution series in measuring bacterial growth?
To measure the viable count
In a continuous culture, what happens to the culture when fresh medium is trickled in at a steady rate?
The culture remains in the exponential phase
What is the reproductive strategy of bacteria and archaea?
Asexual only
What is the reproductive strategy of eukaryotic microbes?
Sexual and asexual
What is the purpose of a chemostat or turbidostat in continuous culture?
To simulate natural environments
When should you inoculate the bacteria in the laboratory experiment?
When the cell concentration reaches 5 x 10^8 cells/ml
What must bacteria and archaea do prior to division?
Replicate and segregate the genome
Which phase of bacterial growth is characterized by cells dividing repeatedly at their maximal rate?
Exponential phase
Which method of counting bacteria is typically carried out by a dilution series and counting only plates with 30-300 colonies?
Viable count
Which optical technique can be used to estimate cell numbers accurately by measuring visible turbidity?
Absorbance method
What is the formula to calculate final number of Cells?
Final cell count = number of cell originally * 2^ number of generation
What is the purpose of the lag phase in bacterial growth?
Regenerate pools of essential nutrients before growth
What is the main reason for the death phase in bacterial growth?
All of the above
Which technique can be used to count cells directly and give an accurate number, but cannot distinguish between living and dead cells?
Petroff-Hauser chamber
In continuous culture using a chemostat, what controls the microbial growth rate?
Flow rate
Which of the following is NOT considered a psychrophile?
An organism with an optimum temperature of 25°C
Which of the following is a characteristic of thermophiles?
Optimum temperature of 60°C
Which of the following types of organisms can grow equally well with or without oxygen?
Aerotolerant anaerobes
Where are biofilms most commonly found?
On conditioned surfaces
What is the term for the density-dependent communication between bacterial cells in biofilms?
Quorum sensing
What is the autoinducer molecule produced by many gram-negative organisms in quorum sensing?
AHL
Which of the following is NOT a factor that may affect microbial growth?
Type of substrate
Which of the following is a characteristic of mesophiles?
Optimum temperature of 30°C
Which of the following is a characteristic of facultative anaerobes?
Grow with or without oxygen, but prefer oxygen
Test your knowledge on microbial growth and its control with this quiz. Learn about concepts such as binary fission, lag, exponential, stationary, and death phases, as well as measuring bacterial growth, dilution series, and continuous culture. Explore the chemical and physical factors that influence growth and their importance in industrial, health, and research settings.
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