Podcast
Questions and Answers
A chemoheterotroph obtains its energy from ______ and its carbon from ______ sources.
A chemoheterotroph obtains its energy from ______ and its carbon from ______ sources.
redox reactions; organic
Human pathogens are classified as?
Human pathogens are classified as?
mesophiles
Organisms that can grow with or without oxygen present are?
Organisms that can grow with or without oxygen present are?
either facultative anaerobes or aerotolerant anaerobes
The ______ growth temperature is the temperature at which an organism exhibits the highest growth rate.
The ______ growth temperature is the temperature at which an organism exhibits the highest growth rate.
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Organisms that require sources of carbon and energy are called ______.
Organisms that require sources of carbon and energy are called ______.
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Which of the following represent the majority of pathogenic bacteria?
Which of the following represent the majority of pathogenic bacteria?
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Obligate anaerobes have enzymes such as superoxide dismutase to protect them from the damaging effects of oxygen.
Obligate anaerobes have enzymes such as superoxide dismutase to protect them from the damaging effects of oxygen.
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A capnophile is a microorganism that thrives in conditions of high...
A capnophile is a microorganism that thrives in conditions of high...
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Microbes in the ______ phase of the microbial growth curve are most susceptible to antimicrobial drugs.
Microbes in the ______ phase of the microbial growth curve are most susceptible to antimicrobial drugs.
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The ______ of a population is the time it takes for the cells to double in number.
The ______ of a population is the time it takes for the cells to double in number.
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A cell that uses an organic carbon source and obtains energy from light would be called a...
A cell that uses an organic carbon source and obtains energy from light would be called a...
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A ______ can measure changes in the turbidity of a bacterial culture.
A ______ can measure changes in the turbidity of a bacterial culture.
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Crenation can result from a change in which of the following?
Crenation can result from a change in which of the following?
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The ______ radical is formed during the incomplete reduction of oxygen during electron transport in aerobes.
The ______ radical is formed during the incomplete reduction of oxygen during electron transport in aerobes.
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A microbiologist inoculates a flask of broth with 1 mL of 100 bacterial cells/mL. The generation time of the species is 1 hour, and there is no lag phase. How long will it be before the culture contains more than 6,000 cells/mL?
A microbiologist inoculates a flask of broth with 1 mL of 100 bacterial cells/mL. The generation time of the species is 1 hour, and there is no lag phase. How long will it be before the culture contains more than 6,000 cells/mL?
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Thermoduric mesophiles are often responsible for spoilage of improperly canned foods.
Thermoduric mesophiles are often responsible for spoilage of improperly canned foods.
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Which of the following does NOT use an inorganic source of carbon as its sole source?
Which of the following does NOT use an inorganic source of carbon as its sole source?
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Which of the following is an indirect method for estimating the number of microbes in a sample?
Which of the following is an indirect method for estimating the number of microbes in a sample?
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What results when a single bacterium reproduces?
What results when a single bacterium reproduces?
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If you begin with six cells, how many cells would you have after three rounds of division?
If you begin with six cells, how many cells would you have after three rounds of division?
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Which of the following is NOT a step in bacterial cell division?
Which of the following is NOT a step in bacterial cell division?
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Which step of binary fission is the reason for genetically identical daughter cells?
Which step of binary fission is the reason for genetically identical daughter cells?
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The generation time of bacterial cells is shortest during the ______ phase.
The generation time of bacterial cells is shortest during the ______ phase.
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A sample placed into fresh medium is initially in the ______ phase of microbial growth in most instances.
A sample placed into fresh medium is initially in the ______ phase of microbial growth in most instances.
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At temperatures higher than the maximum growth temperature for an organism...
At temperatures higher than the maximum growth temperature for an organism...
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When cells are metabolically active but not dividing, they are in the ______ phase.
When cells are metabolically active but not dividing, they are in the ______ phase.
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Which of the following organisms would be most likely to contaminate a jar of pickles?
Which of the following organisms would be most likely to contaminate a jar of pickles?
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Study Notes
Microbial Metabolism and Growth
- Chemoheterotrophs obtain energy from redox reactions and carbon from organic sources.
- Human pathogens are classified as mesophiles, thriving at moderate temperatures.
- Organisms that can grow in the presence or absence of oxygen are either facultative anaerobes or aerotolerant anaerobes.
Growth Characteristics
- The optimum growth temperature is where an organism shows the highest growth rate.
- Generation time refers to the time required for a population to double in number.
- Microbes in the log phase are most susceptible to antimicrobial drugs.
Bacterial Cell Division
- A bacterium reproducing results in two genetically identical daughter cells.
- Inoculating a flask with 100 cells/mL and a generation time of 1 hour leads to more than 6,000 cells/mL after 6 hours without a lag phase.
- Maximum growth temperature damages proteins, breaks hydrogen bonds, and causes membranes to become too fluid.
Environmental Adaptations
- Capnophiles thrive in high carbon dioxide conditions.
- Crenation, or cell shrinkage, results from changes in osmotic pressure.
- Thermoduric mesophiles can spoil improperly canned foods.
Bacterial Growth Measurements
- Turbidity is an indirect method for estimating microbial counts.
- A spectrophotometer can measure changes in the turbidity of bacterial cultures.
Types of Bacteria
- Photoheterotrophs use organic carbon and obtain energy from light; they do not use inorganic carbon sources.
- Acidophiles, which thrive in acidic environments, are most likely to contaminate pickles.
Misconceptions about Bacterial Division
- Obligate anaerobes lack enzymes like superoxide dismutase, which protect from oxygen's effects.
- The disappearance of the nuclear envelope is not a step in bacterial cell division.
Phases of Microbial Growth
- Lag phase is when cells are metabolically active but not dividing, often seen after inoculation into fresh medium.
- Generation time is shortest in the log phase of growth, highlighting rapid division.
Binary Fission
- Genetic identity of daughter cells results from replication of the bacterial chromosome before division.
- After three rounds of division starting with six cells, the culture would grow to 48 cells.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on key concepts from Chapter 6 of your biology curriculum with these flashcards. Covering topics like chemoheterotrophs, human pathogens, and oxygen-related growth classifications, this quiz is a valuable study aid for understanding microbial growth and classification.
