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Questions and Answers
What is the mean division time for the bacteria in population A as stated in the example?
What is the mean division time for the bacteria in population A as stated in the example?
How many times will one bacterium divide in six hours if it has a division time of 20 minutes?
How many times will one bacterium divide in six hours if it has a division time of 20 minutes?
In the context of bacterial growth, what does each division of a bacterium result in?
In the context of bacterial growth, what does each division of a bacterium result in?
What is the final calculation of bacteria after six hours, starting with one bacterium and dividing 18 times?
What is the final calculation of bacteria after six hours, starting with one bacterium and dividing 18 times?
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What are exponents also referred to as?
What are exponents also referred to as?
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Which phase of the bacterial growth curve indicates that bacteria are metabolically active but not dividing?
Which phase of the bacterial growth curve indicates that bacteria are metabolically active but not dividing?
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What mathematical operation is used to express the final population of 262,144 in standard form?
What mathematical operation is used to express the final population of 262,144 in standard form?
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What does the term 'division time' refer to in bacterial growth?
What does the term 'division time' refer to in bacterial growth?
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What occurs during the lag phase of bacterial growth?
What occurs during the lag phase of bacterial growth?
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Which phase of bacterial growth is characterized by the highest rate of cell division?
Which phase of bacterial growth is characterized by the highest rate of cell division?
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What primarily happens during the stationary phase of bacterial growth?
What primarily happens during the stationary phase of bacterial growth?
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During which phase are antibiotics most effective against bacterial cells?
During which phase are antibiotics most effective against bacterial cells?
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What are virulence factors and when are they generated?
What are virulence factors and when are they generated?
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What happens to the population of bacteria during the death phase?
What happens to the population of bacteria during the death phase?
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What is a common characteristic of the exponential (log) phase?
What is a common characteristic of the exponential (log) phase?
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What typically occurs as waste products accumulate in a bacterial culture?
What typically occurs as waste products accumulate in a bacterial culture?
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What is the optimal pH range for alkaliphiles?
What is the optimal pH range for alkaliphiles?
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Which term describes bacteria that grow best in moderate temperatures?
Which term describes bacteria that grow best in moderate temperatures?
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Which type of bacteria can survive in temperatures below 0°C?
Which type of bacteria can survive in temperatures below 0°C?
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What type of bacteria are cyanobacteria classified as?
What type of bacteria are cyanobacteria classified as?
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What distinguishes purple and green bacteria from other photosynthetic bacteria?
What distinguishes purple and green bacteria from other photosynthetic bacteria?
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At what temperature range do thermophiles thrive?
At what temperature range do thermophiles thrive?
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Which type of bacteria is most likely to be found in arctic lakes?
Which type of bacteria is most likely to be found in arctic lakes?
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What is the role of the enzyme secreted by certain bacteria in the stomach?
What is the role of the enzyme secreted by certain bacteria in the stomach?
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What is the role of dying cells in the bacterial life cycle?
What is the role of dying cells in the bacterial life cycle?
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Which type of bacteria requires oxygen for survival?
Which type of bacteria requires oxygen for survival?
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What type of bacteria can grow in low oxygen concentrations but requires oxygen?
What type of bacteria can grow in low oxygen concentrations but requires oxygen?
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Which of the following best describes acidophiles?
Which of the following best describes acidophiles?
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What is the optimal pH level for neutrophiles?
What is the optimal pH level for neutrophiles?
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What metabolic process do facultative anaerobes utilize in oxygen-deprived environments?
What metabolic process do facultative anaerobes utilize in oxygen-deprived environments?
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Which bacteria type does NOT rely on oxygen and can survive its presence?
Which bacteria type does NOT rely on oxygen and can survive its presence?
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Campylobacter jejuni is classified as which type of bacteria based on its oxygen requirement?
Campylobacter jejuni is classified as which type of bacteria based on its oxygen requirement?
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Study Notes
Micro-Organisms and Applications
- Handling microorganisms safely requires specific techniques
- Studying microorganisms provides vital information about their growth and uses
Bacterial Growth
- Bacteria reproduce at regular intervals (e.g., every 20 minutes)
- This allows predictions of bacterial population size over time
Calculating Bacterial Population
- Example: Mean division time for bacteria population A is 20 minutes, starting with one bacterium. Calculate population after six hours.
- Part 1: Calculate the number of divisions. (60 minutes/20minutes per division) x 6 hours = 18 divisions
- Part 2: Calculate the final population. Initial population (1) x 2^(number of divisions) = 262,144 bacteria
- Population size doubles with each division
- Results can also be expressed in scientific notation
Logarithms
- Logarithms are in the form logax
- log525 means "What power of 5 gives 25?"
- Answer is 2 because 52 = 25 (log525 = 2)
Exponents
- Exponents indicate the number of times a number is used in multiplication
- In 82, the "2" indicates using 8 twice in multiplication (8 x 8 = 64)
Phases of Bacterial Growth Cycle
- The bacterial growth curve represents the number of live cells over time
- Four phases: lag, exponential, stationary, and death
- Lag Phase: Active but not dividing
- Exponential Phase: Cells divide rapidly by binary fission. High metabolic activity.
- Stationary Phase: Growth slows; dividing cells equal dying cells.
- Death Phase: Nutrients run out, waste products increase; number of dying cells rise rapidly
Bacterial Growth and Oxygen
- Bacteria require an environment suitable for their growth (oxygen, pH, temperature, light)
- Obligate aerobes: Require oxygen
- Obligate anaerobes: Cannot survive in the presence of oxygen
- Facultative anaerobes: Can grow with or without oxygen
- Aerotolerant anaerobes: Not harmed by oxygen, but can only function without it
- Microaerophiles: Need limited oxygen
Bacterial Growth and pH
- Bacteria thrive in specific pH ranges
- Acidophiles: Thrive in acidic environments (pH < 5)
- Neutrophiles: Thrive in neutral environments (pH near 7)
- Alkaliphiles: Thrive in basic environments (pH 8-10)
Bacterial Growth and Temperature
- Psychrophiles: Thrive in cold temperatures (4-25°C)
- Mesophiles: Thrive in moderate temperatures (20-45°C)
- Thermophiles: Thrive in hot temperatures (50-80°C)
- Hyperthermophiles: Thrive in extremely hot temperatures (80-110°C)
Bacterial Growth and Light
- Some bacteria require light for growth
- Photoautotrophs (e.g., Cyanobacteria): Use light energy for photosynthesis and produce oxygen
- Other bacteria: Use light energy for photosynthesis but don't produce oxygen, using sulfur or sulfide. (e.g., purple and green bacteria)
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Description
This quiz covers safe handling techniques for microorganisms and the calculation of bacterial growth. You'll explore how bacterial populations can be predicted over time and practice using logarithms to better understand exponential growth. Test your knowledge and enhance your understanding of microbiology concepts.
