Foundational Microbiology 3: Microbial Growth and Nutrition

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Which method is used to measure population size when dealing with a large population?

Turbidity

Streaking

Membrane filtration

Serial dilutions (correct)

What happens to the inoculum during streaking across the agar plate?

It is diluted (correct)

It is filtered

It is concentrated

It is incubated

What is the purpose of streaking the inoculum across successive areas of the plate?

To dilute the inoculum (correct)

To concentrate the inoculum

To filter the inoculum

To incubate the inoculum

Which method is used to measure population size when dealing with a small population?

Membrane filtration Signup and view all the answers

What does the membrane filter retain during population size measurement?

Bacterial cells Signup and view all the answers

What is done with the membrane filter after it retains the cells?

It is incubated Signup and view all the answers

What is the purpose of turbidity measurement in population size estimation?

To indirectly estimate the population size Signup and view all the answers

Which method is used for measuring population size when dealing with large populations indirectly?

Turbidity Signup and view all the answers

What is the purpose of incubation in population size measurement?

To allow colonies to form Signup and view all the answers

Which of the following is NOT a characteristic of biofilms?

They are caused by bacterial diseases Signup and view all the answers

What is the purpose of agar in solid media?

To solidify the media Signup and view all the answers

Which type of media contains substances that either favor the growth of particular microorganisms or inhibit the growth of unwanted ones?

Selective media Signup and view all the answers

What is the purpose of differential media?

To differentiate among different bacteria Signup and view all the answers

What is the main purpose of the streak plate method?

To isolate organisms into a pure culture Signup and view all the answers

What is the key requirement for a pure culture?

Aseptic technique Signup and view all the answers

What is the purpose of the Durham tube in carbohydrate utilization tubes?

To trap gas produced during fermentation Signup and view all the answers

During which phase of the microbial growth curve do cells grow at their maximum rate and there are no limitations to nutrients?

Exponential phase Signup and view all the answers

What happens during the stationary phase of the microbial growth curve?

Nutrients are depleted and wastes accumulate Signup and view all the answers

What is the equation used to calculate the log10 number of viable cells at a given time (Nt)?

$Nt = \log_{10} Nt 0$ Signup and view all the answers

What is the lag phase of the microbial growth curve?

Most cells do not reproduce immediately Signup and view all the answers

When does the microbial growth curve reach the long-term stationary phase?

When cells die at a faster rate than they are produced Signup and view all the answers

What happens during the death phase of the microbial growth curve?

Cells die at a faster rate than they are produced Signup and view all the answers

What is the effect of dying cells releasing nutrients during the long-term stationary phase?

Remaining cells feed off these nutrients Signup and view all the answers

Which of the following is true about generation time?

It is the time required for a population of cells to double in number. Signup and view all the answers

What is the generation time for Escherichia coli at 37°C?

0.5 hours Signup and view all the answers

Which of the following organisms has the shortest generation time?

Escherichia coli Signup and view all the answers

Which of the following factors affects microbial growth?

All of the above Signup and view all the answers

Which of the following pH ranges is considered acidic?

0.0-5.5 Signup and view all the answers

Which of the following temperature ranges is suitable for the growth of psychrophiles?

-10°C to 10°C Signup and view all the answers

Which of the following organisms is an obligate anaerobe?

Clostridium botulinum Signup and view all the answers