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Questions and Answers
What is the primary purpose of the cell wall in prokaryotic cells?
What is the primary purpose of the cell wall in prokaryotic cells?
What component is unique to the bacterial cell wall structure?
What component is unique to the bacterial cell wall structure?
Which type of bacteria retains the crystal violet during the Gram staining process?
Which type of bacteria retains the crystal violet during the Gram staining process?
What structure does the DNA of prokaryotic cells reside in?
What structure does the DNA of prokaryotic cells reside in?
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What do Archaea lack in their cell wall compared to bacteria?
What do Archaea lack in their cell wall compared to bacteria?
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What are smaller rings of DNA found in some bacterial species called?
What are smaller rings of DNA found in some bacterial species called?
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In a Gram stain, what color do Gram-negative bacteria appear after the staining process?
In a Gram stain, what color do Gram-negative bacteria appear after the staining process?
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In which type of symbiotic relationship do both organisms benefit?
In which type of symbiotic relationship do both organisms benefit?
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What distinguishes the cell walls of Gram-positive bacteria from those of Gram-negative bacteria?
What distinguishes the cell walls of Gram-positive bacteria from those of Gram-negative bacteria?
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Which type of ecological interaction involves one organism benefiting while the other is neither helped nor harmed?
Which type of ecological interaction involves one organism benefiting while the other is neither helped nor harmed?
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What term is used for parasites that cause disease?
What term is used for parasites that cause disease?
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Which component is often used to classify bacteria through the Gram staining method?
Which component is often used to classify bacteria through the Gram staining method?
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What is the main characteristic of parasitism in ecology?
What is the main characteristic of parasitism in ecology?
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Which of the following statements is true regarding prokaryotic cells?
Which of the following statements is true regarding prokaryotic cells?
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What is the benefit to the host in a mutualistic relationship?
What is the benefit to the host in a mutualistic relationship?
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What does a branch point on a phylogenetic tree represent?
What does a branch point on a phylogenetic tree represent?
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How does the relationship in commensalism differ from that in mutualism?
How does the relationship in commensalism differ from that in mutualism?
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What term is used to describe groups that share an immediate common ancestor?
What term is used to describe groups that share an immediate common ancestor?
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Which of the following terms refers to the study of the relationships between organisms through evolutionary time?
Which of the following terms refers to the study of the relationships between organisms through evolutionary time?
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What does polytomy refer to in a phylogenetic tree?
What does polytomy refer to in a phylogenetic tree?
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What is peptidoglycan primarily associated with?
What is peptidoglycan primarily associated with?
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Which of the following processes involves the transfer of genetic material between organisms of the same generation?
Which of the following processes involves the transfer of genetic material between organisms of the same generation?
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Which of the following best describes bioremediation?
Which of the following best describes bioremediation?
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Which taxon is typically understood to have diverged earliest in a given phylogenetic tree?
Which taxon is typically understood to have diverged earliest in a given phylogenetic tree?
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What characteristic structure do spirochetes possess that aids in their movement?
What characteristic structure do spirochetes possess that aids in their movement?
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Which of the following diseases is caused by Treponema pallidum?
Which of the following diseases is caused by Treponema pallidum?
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What role do cyanobacteria play in the environment?
What role do cyanobacteria play in the environment?
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Which of the following spirochetes can cause Lyme disease?
Which of the following spirochetes can cause Lyme disease?
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Which bacteria is responsible for causing botulism?
Which bacteria is responsible for causing botulism?
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In what way do plant chloroplasts likely relate to cyanobacteria?
In what way do plant chloroplasts likely relate to cyanobacteria?
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Which Gram-positive bacteria are known for their role in soil decomposition?
Which Gram-positive bacteria are known for their role in soil decomposition?
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Which bacterium is known as the source of many antibiotics?
Which bacterium is known as the source of many antibiotics?
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What is the process called when a prokaryotic cell incorporates foreign DNA from its environment?
What is the process called when a prokaryotic cell incorporates foreign DNA from its environment?
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During which process is genetic material transferred unidirectionally from one bacterium to another?
During which process is genetic material transferred unidirectionally from one bacterium to another?
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What role does the F factor play in bacterial conjugation?
What role does the F factor play in bacterial conjugation?
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What type of bacterium becomes a recombinant after it receives DNA from a donor cell during conjugation?
What type of bacterium becomes a recombinant after it receives DNA from a donor cell during conjugation?
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What is transduction in the context of bacterial genetics?
What is transduction in the context of bacterial genetics?
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What does a rooted tree represent in phylogenetics?
What does a rooted tree represent in phylogenetics?
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What characterizes a basal taxon in a phylogenetic tree?
What characterizes a basal taxon in a phylogenetic tree?
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Which statement is true regarding polytomies?
Which statement is true regarding polytomies?
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What do phylogenetic trees not indicate?
What do phylogenetic trees not indicate?
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Which misconception is commonly held about taxa in phylogenetic trees?
Which misconception is commonly held about taxa in phylogenetic trees?
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What is a common trait of domains in biological classification?
What is a common trait of domains in biological classification?
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In the context of a phylogenetic tree, what does a diagram that diverges into multiple groups illustrate?
In the context of a phylogenetic tree, what does a diagram that diverges into multiple groups illustrate?
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Which of the following is NOT a learning objective related to prokaryotes?
Which of the following is NOT a learning objective related to prokaryotes?
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Which is an accurate interpretation of a phylogenetic tree?
Which is an accurate interpretation of a phylogenetic tree?
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What does the term "basal taxon" signify in the context of a phylogenetic tree?
What does the term "basal taxon" signify in the context of a phylogenetic tree?
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What does the term "polytomy" represent in a phylogenetic tree?
What does the term "polytomy" represent in a phylogenetic tree?
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Which statement accurately portrays the limitations of interpreting the relationship of taxa on a phylogenetic tree?
Which statement accurately portrays the limitations of interpreting the relationship of taxa on a phylogenetic tree?
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What type of branching on a phylogenetic tree signifies an unresolved evolutionary relationship where the exact branching order is uncertain?
What type of branching on a phylogenetic tree signifies an unresolved evolutionary relationship where the exact branching order is uncertain?
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Which example best describes the concept of a "rooted tree" in phylogenetics?
Which example best describes the concept of a "rooted tree" in phylogenetics?
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What information does a phylogenetic tree NOT provide directly?
What information does a phylogenetic tree NOT provide directly?
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Which of the following is NOT a primary learning objective regarding prokaryotic features?
Which of the following is NOT a primary learning objective regarding prokaryotic features?
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Which statement accurately describes the function of the F plasmid in bacterial conjugation?
Which statement accurately describes the function of the F plasmid in bacterial conjugation?
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During transduction, which entities are primarily responsible for the movement of genes between bacteria?
During transduction, which entities are primarily responsible for the movement of genes between bacteria?
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What distinct feature allows cells containing the F factor to act as DNA donors during conjugation?
What distinct feature allows cells containing the F factor to act as DNA donors during conjugation?
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What is the result when a recipient bacterium successfully integrates DNA from a donor cell during conjugation?
What is the result when a recipient bacterium successfully integrates DNA from a donor cell during conjugation?
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What differentiates transformation from transduction in bacterial genetics?
What differentiates transformation from transduction in bacterial genetics?
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What structure enables spirochetes to move in a corkscrew motion?
What structure enables spirochetes to move in a corkscrew motion?
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Which of the following bacteria is known to cause a disease related to aquatic environments?
Which of the following bacteria is known to cause a disease related to aquatic environments?
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Which process is hypothesized to be key to the development of plant chloroplasts from cyanobacteria?
Which process is hypothesized to be key to the development of plant chloroplasts from cyanobacteria?
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Which Gram-positive bacterium is most notably linked to a severe infectious disease?
Which Gram-positive bacterium is most notably linked to a severe infectious disease?
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Cyanobacteria are primarily recognized for which ecological function?
Cyanobacteria are primarily recognized for which ecological function?
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Which of the following facts about spirochetes is accurate?
Which of the following facts about spirochetes is accurate?
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Actinomycetes are primarily involved in which ecological process?
Actinomycetes are primarily involved in which ecological process?
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Which characteristic is specific to mycoplasmas compared to other bacteria?
Which characteristic is specific to mycoplasmas compared to other bacteria?
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What characterizes a symbiotic relationship classified as mutualism?
What characterizes a symbiotic relationship classified as mutualism?
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Which ecological relationship results in one organism benefiting while the other is neither helped nor harmed?
Which ecological relationship results in one organism benefiting while the other is neither helped nor harmed?
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What role do plasmids play in prokaryotic cells?
What role do plasmids play in prokaryotic cells?
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In parasitism, what is the relationship between the parasite and its host?
In parasitism, what is the relationship between the parasite and its host?
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What is a distinguishing feature of the nucleoid region in prokaryotic cells?
What is a distinguishing feature of the nucleoid region in prokaryotic cells?
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Which ecological relationship negatively impacts one organism while benefiting another?
Which ecological relationship negatively impacts one organism while benefiting another?
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What is the primary function of the peptidoglycan layer in prokaryotic cells?
What is the primary function of the peptidoglycan layer in prokaryotic cells?
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What do prokaryotes lack compared to eukaryotes regarding genetic material organization?
What do prokaryotes lack compared to eukaryotes regarding genetic material organization?
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What is the primary function of bacterial pili, or sex pili?
What is the primary function of bacterial pili, or sex pili?
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What distinguishes bacterial endospores from other bacterial structures?
What distinguishes bacterial endospores from other bacterial structures?
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Which of the following structures is directly involved in the movement of bacteria?
Which of the following structures is directly involved in the movement of bacteria?
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How does the structure of bacterial flagella compare to those of archaea and eukaryotes?
How does the structure of bacterial flagella compare to those of archaea and eukaryotes?
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What is the primary role of bacterial fimbriae?
What is the primary role of bacterial fimbriae?
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What is the significance of the bacterial capsule?
What is the significance of the bacterial capsule?
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What is the main difference between fimbriae and pili in bacteria?
What is the main difference between fimbriae and pili in bacteria?
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What characteristic do bacterial flagella, archaea flagella, and eukaryotic flagella share?
What characteristic do bacterial flagella, archaea flagella, and eukaryotic flagella share?
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Which statement MOST accurately reflects the impact of prokaryote reproduction on the biosphere?
Which statement MOST accurately reflects the impact of prokaryote reproduction on the biosphere?
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Which of the following statements BEST describes the contribution of prokaryotes to the biosphere?
Which of the following statements BEST describes the contribution of prokaryotes to the biosphere?
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Consider the statement: "There are more prokaryotes in a handful of fertile soil than the number of people who have ever lived." Which of the following BEST explains this statement?
Consider the statement: "There are more prokaryotes in a handful of fertile soil than the number of people who have ever lived." Which of the following BEST explains this statement?
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Why is the statement "Earth's first organisms were likely prokaryotes" considered a valid claim?
Why is the statement "Earth's first organisms were likely prokaryotes" considered a valid claim?
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A scientist studying soil microbes observes that a particular bacterial species significantly increases in number when a specific type of plant root is present. What type of relationship does this observation likely represent?
A scientist studying soil microbes observes that a particular bacterial species significantly increases in number when a specific type of plant root is present. What type of relationship does this observation likely represent?
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Which of the following statements is TRUE about prokaryotic cell structure?
Which of the following statements is TRUE about prokaryotic cell structure?
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Which of the following statements BEST exemplifies the importance of prokaryotes in the biosphere?
Which of the following statements BEST exemplifies the importance of prokaryotes in the biosphere?
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Consider the statement: "Most prokaryotes are unicellular." What is the implication of this statement for the study of prokaryotic evolution?
Consider the statement: "Most prokaryotes are unicellular." What is the implication of this statement for the study of prokaryotic evolution?
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Study Notes
Bacteria and Archaea
- Prokaryotes thrive in diverse environments, including extreme conditions.
- Prokaryotes are microscopic but are abundant; there are more prokaryotes in a handful of fertile soil than the number of humans who have ever lived.
- Prokaryotes are divided into two domains: Bacteria and Archaea.
- Prokaryotic cells are much smaller than eukaryotic cells.
- Prokaryotes have various shapes: spherical (cocci), rod-shaped (bacilli), and spiral.
- Many prokaryotes have a cell wall outside the cell membrane, a feature absent in animal cells. This cell wall maintains shape, protects the cell and prevents bursting due to high water environments.
- Bacterial cell walls contain peptidoglycan.
- Archaea cell walls lack peptidoglycan but contain polysaccharides and proteins.
- Scientists use the Gram stain to classify bacteria by cell wall composition:
- Gram-positive bacteria have a single cell membrane with a large amount of peptidoglycan and stain purple.
- Gram-negative bacteria have a single plasma membrane with less peptidoglycan, and an outer membrane, and stain red.
- The outer membrane of Gram-negative bacteria can be toxic.
- Many antibiotics target peptidoglycan and damage bacterial cell walls, which does not harm human cells, whose cells lack peptidoglycan.
- Some prokaryotes have a capsule that's a polysaccharide or protein layer outside the cell wall as well as fimbriae to stick to a substrate or other cells.
- Pili are longer than fimbriae and allow DNA exchange between prokaryotic cells.
- Most bacteria use flagella for movement, which can be scattered or at one or both ends, and resemble tails.
- Prokaryotes' DNA is located in a nucleoid region, different from eukaryotes' DNA.
- Some prokaryotic species have plasmids, which are smaller rings of DNA.
Symbiosis
- Symbiosis is a close relationship between two species, one a larger host and the smaller symbiont.
- Prokaryotes frequently form symbiotic relationships with larger organisms.
- In mutualism, both symbiotic organisms benefit.
- In commensalism, one organism benefits, while the other is unaffected.
- In parasitism, one organism (the parasite) benefits and the other (the host) is harmed, but not killed.
- Parasites that cause disease are called pathogens.
- Symbiotic relationships can be categorized by the effects on the host and symbiont. (+ = benefit, 0 = no effect, - = harm)
Prokaryotic Reproduction and Genetic Diversity
- Prokaryotes reproduce quickly via binary fission, often every 1-3 hours.
- Offspring are genetically identical from binary fission.
- Rapid reproduction, mutation, and genetic recombination contribute to prokaryotic genetic diversity.
- Short generation time enables swift evolution.
- Genetic recombination, the combination of DNA from two individuals, is achieved through horizontal gene transfer.
- This transfer of genes between individuals from different species is called horizontal gene transfer.
- Prokaryotic DNA can be exchanged through transformation, transduction and conjugation.
- This transfer of genes between individuals from different species is called horizontal gene transfer.
Conjugation and Plasmids
- Conjugation is one-directional gene transfer between prokaryotic cells.
- A donor cell attaches to a recipient using a pilus and transfers DNA.
- The F factor is a piece of DNA necessary for pilus production, allowing the donor cells to transfer DNA to recipient cells.
- The F factor acts as a plasmid that transfers during conjugation. The recipient becomes a recombinant bacterium.
Prokaryotic Metabolism
- Prokaryotic metabolism varies with respect to oxygen (O₂).
- Obligate aerobes require O₂ for cellular respiration.
- Obligate anaerobes are poisoned by O₂, and use fermentation or anaerobic respiration.
- Facultative anaerobes can survive with or without O₂.
- Prokaryotes can fix their own nitrogen a process called "nitrogen fixation". Nitrogen is essential for amino acids and nucleic acids.
Prokaryotic Diversity
- Genetic analysis led to the division of prokaryotes into two domains: Bacteria and Archaea.
- The Bacteria domain is further divided into 6 major groups: Proteobacteria, Green bacteria, Chlamydias, Spirochetes, Cyanobacteria, and Gram-positive bacteria.
Archaea
- Archaea share traits with both Bacteria and Eukaryotes.
- Some archaea, called extremophiles, live in extreme environments (e.g., highly saline conditions or very hot environments).
- Methanogens live in swamps and marshes and produce methane as a waste product.
- Methanogens are strict anaerobes.
Prokaryotes in the Biosphere
- Prokaryotes are essential for chemical recycling (decompose waste and dead organisms).
- Prokaryotes help convert nitrogen, phosphorus, and potassium to useable forms, encouraging plant growth.
- Many are present in the intestines of most living organisms aiding in digestion & nutrient absorption.
- Prokaryotes are used in bioremediation, removing pollutants.
- Bacteria can be engineered to produce various substances like vitamins, antibiotics, and hormones.
- Bacteria are being used in the production of ethanol from agricultural & municipal waste biomass, switchgrass, and corn.
Prokaryotes in Research and Technology
- Research with prokaryotes leads to advances in DNA technology, such as gene cloning and producing transgenic plants.
- Prokaryotes can be used to create natural plastics.
- Some bacteria are used in biological warfare.
- Bacteria play a role in food spoilage.
Next Lecture
- Students are to bring notecards for every class, do Chapter 27 homework and the quiz on Blackboard, and optionally read Chapter 27.
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Description
Test your knowledge on prokaryotes, specifically Bacteria and Archaea. This quiz covers their characteristics, classification, and differences from eukaryotic cells. Explore the diverse environments in which these microscopic organisms thrive.
