Foundational Microbiology 3: Microbial Growth and Nutrition

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Questions and Answers

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?

<p>Membrane filtration (A)</p> Signup and view all the answers

What does the membrane filter retain during population size measurement?

<p>Bacterial cells (A)</p> Signup and view all the answers

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

<p>It is incubated (D)</p> Signup and view all the answers

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

<p>To indirectly estimate the population size (B)</p> Signup and view all the answers

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

<p>Turbidity (C)</p> Signup and view all the answers

What is the purpose of incubation in population size measurement?

<p>To allow colonies to form (D)</p> Signup and view all the answers

Which of the following is NOT a characteristic of biofilms?

<p>They are caused by bacterial diseases (B)</p> Signup and view all the answers

What is the purpose of agar in solid media?

<p>To solidify the media (C)</p> 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?

<p>Selective media (D)</p> Signup and view all the answers

What is the purpose of differential media?

<p>To differentiate among different bacteria (C)</p> Signup and view all the answers

What is the main purpose of the streak plate method?

<p>To isolate organisms into a pure culture (D)</p> Signup and view all the answers

What is the key requirement for a pure culture?

<p>Aseptic technique (A)</p> Signup and view all the answers

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

<p>To trap gas produced during fermentation (C)</p> 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?

<p>Exponential phase (B)</p> Signup and view all the answers

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

<p>Nutrients are depleted and wastes accumulate (C)</p> Signup and view all the answers

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

<p>$Nt = \log_{10} Nt 0$ (B)</p> Signup and view all the answers

What is the lag phase of the microbial growth curve?

<p>Most cells do not reproduce immediately (B)</p> Signup and view all the answers

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

<p>When cells die at a faster rate than they are produced (C)</p> Signup and view all the answers

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

<p>Cells die at a faster rate than they are produced (A)</p> Signup and view all the answers

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

<p>Remaining cells feed off these nutrients (B)</p> Signup and view all the answers

Which of the following is true about generation time?

<p>It is the time required for a population of cells to double in number. (D)</p> Signup and view all the answers

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

<p>0.5 hours (D)</p> Signup and view all the answers

Which of the following organisms has the shortest generation time?

<p>Escherichia coli (A)</p> Signup and view all the answers

Which of the following factors affects microbial growth?

<p>All of the above (D)</p> Signup and view all the answers

Which of the following pH ranges is considered acidic?

<p>0.0-5.5 (C)</p> Signup and view all the answers

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

<p>-10°C to 10°C (D)</p> Signup and view all the answers

Which of the following organisms is an obligate anaerobe?

<p>Clostridium botulinum (D)</p> Signup and view all the answers

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