Microbiology: An Introduction

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Questions and Answers

Why is the study of microbial interactions with other organisms considered important?

Because these interactions have no effect on environmental processes.
Because only macroscopic organisms impact ecosystem functions.
Because these interactions lead to the creation of various products and influence ecological balance. (correct)
Because microbes are too small to be seen without a microscope.

Which characteristic distinguishes archaea from bacteria?

Archaea possess linear DNA enclosed within a membrane-bound nucleus.
Archaea's membrane lipids and proteins create extremophile characteristics using pseudopeptidoglycan. (correct)
Archaea have peptidoglycan in their cell walls.
Archaea replicate through mitosis, whereas bacteria use binary fission.

Why are protists considered a paraphyletic group, rather than a distinct kingdom?

Protists are a diverse group in which members of other groups can also be found. (correct)
Protists uniquely consist of prokaryotic cells, unlike fungi, which are eukaryotic.
Protists are different in that their cell walls contain cellulose, unlike fungi.
Protists are fully classified due to their specific characteristics and behaviors.

How does ribosomal RNA (rRNA) influence the classification of organisms into three domains of life?

Differences in rRNA sequences led to the creation of the three domains because rRNA is part of the ribosome. (A)

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Explain the role of peptidoglycan in the context of bacterial cells.

Peptidoglycan provides a unique cell wall in prokaryotic cells which supports cell structure and morphology. (D)

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How does the presence or absence of a nuclear membrane affect cellular processes?

The presence of a nuclear membrane permits more complex control over where transcription occurs relative to translation. (B)

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What determines whether bacteria are classified as Gram-positive or Gram-negative?

The existence of a peptidoglycan layer and either mono or diderm bacteria. (B)

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How do bacterial capsules support immune evasion?

Masking surface antigens and opsonization. (D)

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What specialized structures enable bacteria to sense magnetic fields, and what advantage does this adaptation convey?

Magnetotactic bacteria use magnetosomes to orient in magnetic fields. (D)

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How does a bacterial endospore improve bacteria ability to adapt to environmental stress?

It allows the bacterium to persist in a temporarily inactive state. (D)

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What is the primary role of the bacterial cytoskeleton?

The primary role is to give cell shape and support the cell membrane. (A)

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How does the bacterial flagellum function to determine the direction of movement?

By controlling the direction of force, the bacterial flagellum generates a rotational and directional whip-like motion. (C)

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How do the differences in the actions of MreB and CreS determine the shape of bacterial cells?

Bacterial shapes are determined by MreB's role in rod shape and CreS's role in creating curved shapes. (C)

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How do bacteria exchange genetic material through conjugation, and what elements are essential for this mechanism?

Bacterial conjugation creates a transfer of plasmids to enable the formation of a specialized structure. (B)

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How do Type IV secretion systems affect a cell's cellular constitution to share materials?

The Type IV creates a pathway with a pore that can push some cell wall, but remains a stable channel. (C)

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What factors influence whether bacteria will express specific genes, and how is this regulated?

Horizontal gene transfer as well as sporulation is not what this depends on. It depends on stimuli, which lead to direct shifts due to genetic regulatory processes. (A)

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How does horizontal gene transfer aid in adaptation and the sharing of traits?

Horizontal transfer allows new DNA to be expressed or even recombination to take place in the bacteria. (B)

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What are the advantages and disadvantages of organisms classified based on bacterial shapes?

Different shapes are directly correlated to environmental pressures, and is only adaptive to specific species. (D)

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Why does cellular adaptation reduce a species ability to diversify its genetic material?

Cellular adaptation is a strategy to reduce genetic material across a long timeframe to focus on survival. (A)

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Which of the following represents the most accurate comparison between eukaryotic flagella and prokaryotic flagella?

As an organelle within flagellates, eukaryotic flagella are not homologous and do not share similarity to prokaryotic flagella. (B)

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How does electrostatic repulsion contribute to immune evasion in some bacteria?

Polysaccharides create electrostatic repulsion that disrupts electrostatic recognition and immune functions. (B)

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What specialized feature do some species harness to adhere to the surfaces of host cells?

Having fimbriae and adhesive proteins contributes to an organism's ability for adhesion. (A)

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How are bacteria recognized in cases where biofilms secrete molecules to alter the immune system?

Biofilms require secreted molecules that induce responses such as suppressing cytokine. (B)

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When considering bacterial attachment to surfaces, what distinguishes the functions of capsule glycocalyx and biofilm matrices?

Capsule glycocalyx facilitates immune function, whereas biofilm matrix provides physical structure and stress resistance. (B)

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How does the presence of persister cells within a bacterial biofilm challenge antibiotic efficacy?

Their dormant state does not have antigens which the drugs target and can withstand treatment or other conditions. (B)

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How do bacteria change under stressed environments?

Environmental stressors can lead to the expression of new phenotypes due to horizontal gene transfer. (C)

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In what way do surface-exposed proteins in Gram-positive bacteria influence cell function, and what mechanisms are involved?

There are a number of cell wall actions driven by surface proteins, which influence structure, recognition and function. (C)

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Which of the following correctly describes differences between a virus and bacterial cell?

Bacterial cells are biological machines that often act as the host cell for a virus. (D)

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What role does the presence or absence of membrane-bound organelles play in the overall function of an organism?

Membrane-bound organelles increase function across the cell of eukaryotes. (D)

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In Gram-negative bacteria, what is the significance of the O-antigen component of lipopolysaccharides (LPS)?

Shifts due to environmental adaptations make the O-antigen difficult to be recognized by the host immune system. (B)

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How does maintaining turgor pressure relate to bacterial cell integrity, and what mechanisms are employed to regulate it?

Bacteria can have rigid/ structural strength which allows some rigidity. (D)

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How does a small aquatic body help maintain some marine species? (Describe their structure, then give a related application).

Gas vesicles make it the marine species has buoyancy for photosynthesis. (B)

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How are carbon structures essential inside photosynthesis?

Organic carbon supports the photosynthetic reaction in some bacteria. (B)

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How does the nanostructure in bacteria support biofilm function?

Nanowires enable only long range electron transfer in a biofilm. (D)

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Flashcards

Microbiology

Study of microscopic organisms (viruses, bacteria, algae, fungi, and protozoa) and their functions.

Bacteriology

Studies bacteria, including identification, classification, and characteristics.