Microbial Growth/ Control

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Which of the following is a characteristic that effects microbial growth?

Chemical and physical factors (correct)

Continuous culture

Reproductive strategies

Binary fission

What is the purpose of a dilution series in measuring bacterial growth?

To identify the growth phases

To measure the viable count (correct)

To determine the lag phase

To estimate the cell count

In a continuous culture, what happens to the culture when fresh medium is trickled in at a steady rate?

The culture reaches the death phase

The culture enters the stationary phase

The culture remains in the exponential phase (correct)

The culture undergoes binary fission

What is the reproductive strategy of bacteria and archaea?

Asexual only Signup and view all the answers

What is the reproductive strategy of eukaryotic microbes?

Sexual and asexual Signup and view all the answers

What is the purpose of a chemostat or turbidostat in continuous culture?

To simulate natural environments Signup and view all the answers

When should you inoculate the bacteria in the laboratory experiment?

When the cell concentration reaches 5 x 10^8 cells/ml Signup and view all the answers

What must bacteria and archaea do prior to division?

Replicate and segregate the genome Signup and view all the answers

Which phase of bacterial growth is characterized by cells dividing repeatedly at their maximal rate?

Exponential phase Signup and view all the answers

Which method of counting bacteria is typically carried out by a dilution series and counting only plates with 30-300 colonies?

Viable count Signup and view all the answers

Which optical technique can be used to estimate cell numbers accurately by measuring visible turbidity?

Absorbance method Signup and view all the answers

What is the formula to calculate final number of Cells?

Final cell count = number of cell originally * 2^ number of generation Signup and view all the answers

What is the purpose of the lag phase in bacterial growth?

Regenerate pools of essential nutrients before growth Signup and view all the answers

What is the main reason for the death phase in bacterial growth?

All of the above Signup and view all the answers

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 Signup and view all the answers

In continuous culture using a chemostat, what controls the microbial growth rate?

Flow rate Signup and view all the answers

Which of the following is NOT considered a psychrophile?

An organism with an optimum temperature of 25°C Signup and view all the answers

Which of the following is a characteristic of thermophiles?

Optimum temperature of 60°C Signup and view all the answers

Which of the following types of organisms can grow equally well with or without oxygen?

Aerotolerant anaerobes Signup and view all the answers

Where are biofilms most commonly found?

On conditioned surfaces Signup and view all the answers

What is the term for the density-dependent communication between bacterial cells in biofilms?

Quorum sensing Signup and view all the answers

What is the autoinducer molecule produced by many gram-negative organisms in quorum sensing?

AHL Signup and view all the answers

Which of the following is NOT a factor that may affect microbial growth?

Type of substrate Signup and view all the answers

Which of the following is a characteristic of mesophiles?

Optimum temperature of 30°C Signup and view all the answers

Which of the following is a characteristic of facultative anaerobes?

Grow with or without oxygen, but prefer oxygen Signup and view all the answers