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Questions and Answers
Which of the following is NOT a reason microbes can be difficult to classify?
Which of the following is NOT a reason microbes can be difficult to classify?
- As asexual organisms, the species concept does not apply to them.
- They can exchange genes in non-sexual ways.
- Their DNA is easily acquired, amplified, and compared using modern techniques. (correct)
- They are difficult to distinguish using microscopy or culture.
Which one of the following is NOT one of Koch's postulates?
Which one of the following is NOT one of Koch's postulates?
- When the microbe is introduced into a healthy, susceptible host, the same disease occurs.
- The microbe is isolated from the diseased host and grown in pure culture.
- The microbe becomes more virulent with each successive host. (correct)
- The microbe is found in all cases of disease, but is absent in healthy individuals.
Though there are some exceptions and contradictions to the definition, which of the below best fits the definition of a microbe?
Though there are some exceptions and contradictions to the definition, which of the below best fits the definition of a microbe?
- Any virus
- Any disease-causing organism
- Any bacteria
- Any organisms that require a microscope to be seen (correct)
The collection of sequences sampled from a particular environmental sample is called:
The collection of sequences sampled from a particular environmental sample is called:
A pure culture refers to:
A pure culture refers to:
Which of the following is true of viruses?
Which of the following is true of viruses?
Which of the following organisms are not considered microbes?
Which of the following organisms are not considered microbes?
Pure cultures:
Pure cultures:
Koch's postulates are criteria used to establish that:
Koch's postulates are criteria used to establish that:
Which of the following is a unique characteristic of viruses that distinguishes them from the other major groups of microorganisms?
Which of the following is a unique characteristic of viruses that distinguishes them from the other major groups of microorganisms?
The reduction of N2 gas into ammonia is known as:
The reduction of N2 gas into ammonia is known as:
Which scientist contributed to disproving spontaneous generation?
Which scientist contributed to disproving spontaneous generation?
Substances that are naturally produced by microorganisms and that can inhibit or destroy other microorganisms are called _____
Substances that are naturally produced by microorganisms and that can inhibit or destroy other microorganisms are called _____
Regarding the classification of microbes, which of the following among A-C is false?
Regarding the classification of microbes, which of the following among A-C is false?
The first person to visualize a microbe was:
The first person to visualize a microbe was:
The 'rock-eating' bacteria are typically known as:
The 'rock-eating' bacteria are typically known as:
How did early microbial ecologists determine that microbes are responsible for ecological reactions?
How did early microbial ecologists determine that microbes are responsible for ecological reactions?
Penicillin is:
Penicillin is:
Archaea are prokaryotic cells, yet based on the comparative analysis of _____ archaea are more closely related to eukaryotes than to bacteria.
Archaea are prokaryotic cells, yet based on the comparative analysis of _____ archaea are more closely related to eukaryotes than to bacteria.
Dr. Rita Colwell originated the concept of 'viable but nonculturable' microorganisms. Which of the following best describes this concept?
Dr. Rita Colwell originated the concept of 'viable but nonculturable' microorganisms. Which of the following best describes this concept?
Based on the following DNA sequence comparisons, which two unidentified microorganisms would you conclude are most closely related?
Based on the following DNA sequence comparisons, which two unidentified microorganisms would you conclude are most closely related?
Identify which organisms can be infected by viruses.
Identify which organisms can be infected by viruses.
Louis Pasteur and his swan-necked flask. This apparatus was used to show that:
Louis Pasteur and his swan-necked flask. This apparatus was used to show that:
The theory that organisms can arise from inanimate matter is called:
The theory that organisms can arise from inanimate matter is called:
Archaeans:
Archaeans:
Most organisms (including you) break down organic compounds to obtain energy and nutritional building blocks. In contrast, chemolithotrophs are prokaryotes that obtain energy through the oxidation of inorganic compounds. Which of the following inorganic molecules would these microbes also need to build macromolecules for new cell material?
Most organisms (including you) break down organic compounds to obtain energy and nutritional building blocks. In contrast, chemolithotrophs are prokaryotes that obtain energy through the oxidation of inorganic compounds. Which of the following inorganic molecules would these microbes also need to build macromolecules for new cell material?
The use of microbial metabolism to remove or neutralize human waste and industrial pollutants is known as _____
The use of microbial metabolism to remove or neutralize human waste and industrial pollutants is known as _____
Identify which two of Koch's postulates would most likely not be fulfilled when trying to link a human virus to a particular disease.
Identify which two of Koch's postulates would most likely not be fulfilled when trying to link a human virus to a particular disease.
While repeating Pasteur's experiment with the swan-necked flask, John Tyndall occasionally observed the opposite result. Tyndall noticed that the boiled broth in the swan-necked flask sometimes did give rise to microorganisms. Accordingly, he demonstrated that the broth was contaminated with _____
While repeating Pasteur's experiment with the swan-necked flask, John Tyndall occasionally observed the opposite result. Tyndall noticed that the boiled broth in the swan-necked flask sometimes did give rise to microorganisms. Accordingly, he demonstrated that the broth was contaminated with _____
Which characteristic of endospores led to confusion when Tyndall tried to replicate Pasteur's experiments regarding spontaneous generation?
Which characteristic of endospores led to confusion when Tyndall tried to replicate Pasteur's experiments regarding spontaneous generation?
Antibiotics are:
Antibiotics are:
During a period of time outside the host, a virus may become _____ and lose many factors that are required for infections. These viruses stimulate the immune system with much lower mortality than the fully virulent strains.
During a period of time outside the host, a virus may become _____ and lose many factors that are required for infections. These viruses stimulate the immune system with much lower mortality than the fully virulent strains.
The figure below shows a Winogradsky column. High levels of oxygen are available on the upper layers and can be used as an electron acceptor. Which organisms would you expect to use other electron acceptors?
The figure below shows a Winogradsky column. High levels of oxygen are available on the upper layers and can be used as an electron acceptor. Which organisms would you expect to use other electron acceptors?
Which of the following is a difference between antiseptics and antibiotics?
Which of the following is a difference between antiseptics and antibiotics?
In 1899, Beijerinck found that the infectious agent of tobacco mosaic disease went through a filter of 0.1μm pore size. Stanley later purified and crystallized the infectious agent from infected tobacco leaves. The infectious agent was found to be a(n):
In 1899, Beijerinck found that the infectious agent of tobacco mosaic disease went through a filter of 0.1μm pore size. Stanley later purified and crystallized the infectious agent from infected tobacco leaves. The infectious agent was found to be a(n):
Sergei Winogradsky:
Sergei Winogradsky:
Early microscopes:
Early microscopes:
Which of the following would allow a disease-causing microbe NOT to adhere to Koch's postulates?
Which of the following would allow a disease-causing microbe NOT to adhere to Koch's postulates?
Carl Woese proposed the domain classification
Carl Woese proposed the domain classification
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Study Notes
Classification Challenges of Microbes
- Microbes possess DNA that is readily acquired and analyzed but exhibit difficulties in classification.
- Asexual reproduction complicates the application of traditional species concepts.
- Microbial gene exchange occurs through non-sexual processes, complicating classification.
- Distinction of microbes via microscopy or culture poses significant challenges.
Koch's Postulates
- Koch's postulates provide a framework to confirm the causative relationship between microbes and diseases.
- One postulate states that the microbe must be isolated from the diseased host and reacquired through pure culture.
- Another asserts the microbe should be present in diseased hosts but absent in healthy individuals.
- The assertion that a microbe becomes more virulent with each host is NOT a postulate.
Definition of Microbes
- Microbes are defined as organisms that cannot be seen without a microscope, including bacteria, viruses, fungi, and protozoa.
Metagenome
- Metagenomes refer to the collective sequences derived from an environmental sample, highlighting microbial diversity.
Pure Culture Definition
- A pure culture consists of a single type or strain of microorganism, critical for studying specific pathogens.
Characteristics of Viruses
- Viruses are non-cellular entities, distinguishing them from prokaryotic and eukaryotic organisms.
Non-Microbial Organisms
- Mosquitoes are not classified as microbes, whereas viruses, bacteria, fungi, and protozoa are.
Characteristics of Pure Cultures
- Pure cultures originate from isolated microbial species, which can arise from mixed samples through specific techniques like serial dilution.
Contributions of Scientists
- John Tyndall played a significant role in demonstrating the refutation of spontaneous generation.
- Antoine van Leeuwenhoek was the first to visualize microbes under a microscope.
Antibiotics
- Antibiotics are natural substances produced by microorganisms that can inhibit or kill other microbes.
- They may sometimes be overprescribed, leading to resistance issues.
Nitrogen Fixation
- Nitrogen fixation is the biochemical process that converts nitrogen gas (N2) into ammonia.
Bioremediation
- The use of microbial metabolism for the removal or neutralization of pollutants is termed bioremediation.
Empirical Observations
- Early microbial ecologists determined microbial roles in environmental reactions through experimental contamination studies and pure culture observations.
Endospores and Confusion in Experiments
- Tyndall's replication attempts were complicated by the presence of heat-resistant endospores, leading to occasional microbial growth in seemingly sterile conditions.
Differences in Microbial Substances
- Antiseptics and antibiotics serve differing roles; antibiotics can be administered internally, while antiseptics are primarily for surface application.
Classification of Microorganisms
- The domain classification proposed by Carl Woese includes two distinct prokaryotic groups—Archaea and Bacteria—besides Eukarya.
Viral Infections
- Viruses can infect a wide range of organisms: animals, plants, archaea, bacteria, fungi, and protists.
Tyndall's Contributions
- Tyndall provided insights into microbial persistence and variation in results due to contaminants in experimental setups.
Pathogen Adherence to Koch's Postulates
- Some pathogens, like those causing rabies, can infect multiple species, complicating adherence to Koch's postulates due to variability in infection outcomes.
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