What is the function of fimbriae?
A. They are used in motility.
B. They are used to transfer DNA during conjugation.
C. They are components of the outer cell wall in gram-negative bacteria.
D. They protect the cell from dehydration.
E. They are used to attach the cell to its substrate or to other prokaryotes.
answer
E. They are used to attach the cell to its substrate or to other prokaryotes.
They are hair-like projections that aid in attachment. They are also known as attachment pili to distinguish them from the pili used in conjugation.
question
How does the large amount of genetic variation observed in prokaryotes arise?
A. The mutation rate in prokaryotes is much higher than in eukaryotes.
B. They have extremely short generation times and large populations.
C. They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer.
D. They have a relatively small genome.
E. The second and third answers are correct.
answer
E. The second and third answers are correct.
The short generation times and large population sizes in most prokaryotic species, coupled with their ability to exchange genes, helps to increase genetic variability beyond what we would expect in asexually reproducing organisms.
question
Genes for the resistance to antibiotics are usually located _____.
A. in mitochondria
B. on the main chromosome
C. on plasmids
D. in eukaryotic cells
E. on the outside of the cell wall
answer
C. on plasmids
Genes for the resistance to antibiotics are usually located on plasmids.
question
gram-positive bacteria
answer
1.) Have a thick layer of peptidoglycan
2.) Appear purple after Gram staining
3.) Alcohol rinse does not remove crystal violet
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gram-negative bacteria
answer
1.) Have a thin layer of peptidoglycan
2.) Appear pink after Gram staining
3.) Have an outer membrane as part of their cell-wall structure
4.) Alcohol rinse does remove crystal violet
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gram-positive/ gram-negative bacteria
answer
1.) Both have a plasma membrane
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Autotroph
answer
Require energy only from inorganic sources
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Heterotroph
answer
Require energy from atlas one organic nutrient
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Phototrophs
answer
Use light as energy source
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Chemotrophs
answer
Use chemicals as energy source
question
Azotobacter is a genus of bacteria that live in soil and have the following characteristics:
- They are bacilli.
- They are gram-negative.
- They are obligate aerobes.
- They can fix nitrogen. (Unlike some other nitrogen-fixing bacteria, which associate with the roots of plants, Azotobacter species are free-living.)
answer
1.) They use O2 for cellular respiration
2.) They can convert atmospheric nitrogen to ammonia
3.) They are shaped like rods
4.) They have a relatively thin layer of peptidoglycan in their cell wall
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Cocci
answer
spherical prokaryotes
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Bacilli
answer
rod-shaped prokaryotes
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Spirilla
answer
spiral prokaryotes
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Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____.
A. chemoheterotrophs
B. photoheterotrophs
C. chemoautotrophs
D. photoautotrophs
answer
C. chemoautotrophs
They use inorganic molecules (in redox reactions) for energy, and carbon dioxide for carbon.
question
Which statement is true about obligate anaerobes?
A. They will use O2 if it is present, but can obtain energy by fermentation if needed.
B. They obtain energy by oxidizing ferrous ions.
C. They use O2 for cellular respiration and cannot grow without it.
D. They live exclusively by cellular respiration or by anaerobic respiration.
E. They are poisoned by O2.
answer
E. They are poisoned by O2.
Some obligate anaerobes live exclusively by fermentation; others extract chemical energy by anaerobic respiration, in which substances other than O2 accept electrons at the "downhill" end of electron transport chains.
question
The prokaryotic cells that built stromatolites are classified as _____.
A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
E. cyanobacteria
Cyanobacteria built stromatolites.
question
The prokaryotic cells that were the first to add significant quantities of oxygen to Earth's atmosphere are classified as _____.
A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
E. cyanobacteria
Cyanobacteria are aerobic photosynthesizers.
question
Streptococcus pyogenes is classified with _____.
A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
D. gram-positive bacteria
S. pyogenes attracts the violet Gram stain.
question
Organisms that can cause nongonococcal urethritis are classified with _____.
A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
B. chlamydias
Chlamydia trachomatis causes nongonococcal urethritis.
question
The chemoheterotroph Proteus vulgaris is a rod-shaped bacterium classified with _____.
A. proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
A. proteobacteria
Proteus vulgaris is classified with proteobacteria.
question
Spiral-shaped bacteria are likely to be placed with _____.
A.proteobacteria
B. chlamydias
C. spirochetes
D. gram-positive bacteria
E. cyanobacteria
answer
C. spirochetes
The name of these organisms provides the answer to the question.
question
The prokaryotic organisms most likely to be found living in salt ponds are the _____.
A. thermophiles
B. methanogens
C. Korarchaeota
D. extremophiles
E. halophiles
answer
E. halophiles
These archaea live in salty environments such as the Dead Sea.
question
How are archaeans most similar to bacteria?
A.the structure of their cell walls
B. methanogenesis
C. the occurrence of introns in their chromosomes
D. nucleotide sequence of small subunit ribosomal RNA
E. the shape of their chromosomes and plasmids
answer
E. the shape of their chromosomes and plasmids
Prokaryotes typically have circular chromosomes and plasmids
question
An ecological relationship between organisms of different species that are in direct contact can best be described as _____.
A. taxis
B. commensal
C. symbiotic
D. mutualistic
E. parasitic
answer
C. symbiotic
This is the definition of symbiosis.
question
Which statement about endotoxins is true?
A. The source of endotoxins is endospores.
B. Endotoxins are released only when bacteria die and their cell walls break down.
C. Endotoxins are proteins secreted by prokaryotes.
D. An example of a prokaryote that produces endotoxins is Clostridium botulinum.
E. Endotoxins are components of the cell wall of gram-positive bacteria.
answer
B. Endotoxins are released only when bacteria die and their cell walls break down.
Endotoxins are a component of the outer membrane of gram-negative bacteria.
question
Bioremediation is _____.
A. the use of prokaryotes in producing pharmaceutical products
B. the modification of prokaryotes for industrial purposes
C. the use of organisms to remove pollutants from the environment
D. the use of biological processes to remedy diseases
E. the use of prokaryotes in producing transgenic organisms
answer
C. the use of organisms to remove pollutants from the environment
This is the general use of the term bioremediation.
question
Select the valid comparison between eukaryotes and prokaryotes.
A.Eukaryotes are far more metabolically diverse than prokaryotes.
B. Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells.
C. The total biomass of eukaryotes is approximately ten times the total biomass of prokaryotes.
answer
B. Prokaryote cells have simpler internal structure and genomic organization than eukaryotic cells.
Read about the internal and genomic organization of prokaryotes.
question
Which of the following processes contributes to genetic recombination in prokaryotes?
Which of the following processes contributes to genetic recombination in prokaryotes?
A.) Transduction
B.) Mutation
C.) Meiosis
answer
A.) Transduction
In transduction, bacteriophages carry bacterial genes from one host cell to another, producing a recombinant bacterial genome. Read about the other processes that contribute to genetic recombination in prokaryotes.
question
Peptidoglycan
answer
A polymer composed of modified sugars cross-linked by short polypeptides. This molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface.
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Capsule
answer
Is a sticky layer of polysaccharide or protein that surrounds the cell wall of many prokaryotes.
question
Endospores
answer
Resistant cells bacteria develop when they lack an essential nutrient in a way to withstand harsh conditions.
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Fimbriae
answer
Hairlike appendages some prokaryotes use to stick to their substrate or to one another.
question
Pili
answer
Appendages (longer than fimbriae) that pull two cells together prior to DNA transfer from one cell to another.
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Taxis
answer
A directed movement toward or away from a stimulus.
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Nucleoid
answer
Where the chromosome is located in a prokaryote; region of the cytoplasm that is not enclosed by a membrane.
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Plasmids
answer
Small rings of independently replicating DNA molecules.
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Transformation
answer
Where the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings.
question
Transduction
answer
When phages carry prokaryotic genes from one host cell to another.
question
Conjugation
answer
DNA is transferred between two prokaryotic cells that are temporarily joined.
question
F factor
answer
A particular piece of DNA that allows the ability to form pili and donate DNA during conjugation.
question
R plasmids
answer
"resistance genes" which code for enzymes that specifically destroy or otherwise hinder the effectiveness of certain antibiotics, such as tetracycline or ampicillin.
question
Obligate aerobes
answer
Must use O2 for cellular respiration.
question
Obligate anaerobes
answer
Poisoned by O2; some live exclusively by fermentation; others extract chemical energy by anaerobic respiration.
question
Facultative anaerobes
answer
Can use O2 if its present but can also carry out fermentation or anaerobic respiration.
question
Nitrogen fixation
answer
Some cyanobacteria and some methanogens convert atmospheric nitrogen (N2) to ammonia (NH3).
question
Extreme halophiles
answer
Live in highly saline environments.
question
Extreme thermophiles
answer
Thrive in very hot environments.
question
Methanogens
answer
Arachaea that release methane as a by-product of their unique ways of obtaining energy.
question
Decomposers
answer
Break down dead organisms and waste products unlocking supplies of carbon, nitrogen, and other elements.
question
Symbiosis
answer
An ecological relationship in which two species live in close contact of one another.
question
Mutualism
answer
+ +
question
Commensalism
answer
+ 0
question
Parasitism
answer
+ -
question
Pathogens
answer
Parasites that cause disease.
question
Exotoxins
answer
Are proteins secreted by certain bacteria and other organisms.
question
Endotoxins
answer
Are lipopolysaccharide components of the outer membrane of gram-negative bacteria. They are only released when bacteria die and their cell walls break down.
question
Genetic variation in bacterial populations cannot result from
A. transduction
B. conjugation
C. mutation
D. meiosis
answer
D. meiosis
question
Photoautotrophs use
A. light as energy source and CO2 as a carbon source.
B. light as energy source and methane as a carbon source.
C. N2 as an energy source and CO2 as a carbon source.
D. CO2 as both an energy source and a carbon source.
answer
A. light as energy source and CO2 as a carbon source.
question
Which of the following involves metabolic cooperation among prokaryotic cells?
A. binary fission
B. endospore formation
C. biofilms
D. photoautotrophy
answer
C. biofilms
question
Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?
A. skin commensalist
B. decomposer
C. gut mutualist
D. pathogen
answer
B. decomposer
question
Plantlike photosynthesis that releases O2 occurs in
A. cyanobacteria
B. gram-positive bacteria
C. archaea
D. chemoautotrophic bacteria
answer
A. cyanobacteria
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