Microbiology Chapter 14 Test Bank

Microbiology Chapter 14 Test Bank Related

Review Microbiology Chapter 14 Test Bank related questions and content

A patient underwent esophagogastroduodenoscopy. Analysis of the biopsy material enabled doctors to diagnose him with helicobacteriosis. What property of the bacteria found in this patient had to be obligatory taken into account during their cultivation?

  • A. Microaerophilic ability
  • B. Presence of urease
  • C. Absence of spores and capsules
  • D. Colonisation of gastral cells
Correct Answer: A

Rationale: Step-by-step rationale for why choice A is correct:
1. Helicobacter pylori, the bacteria causing helicobacteriosis, is microaerophilic, requiring low oxygen levels.
2. Cultivation conditions must mimic the natural environment of the bacteria.
3. Failure to provide a microaerophilic environment can hinder bacterial growth.
4. Thus, the ability to cultivate these bacteria requires consideration of their microaerophilic nature.

Summary:
- Choice A is correct because Helicobacter pylori is a microaerophilic bacteria.
- Choice B (Presence of urease) is incorrect as it is a characteristic used for diagnosis, not cultivation.
- Choice C (Absence of spores and capsules) is incorrect as it does not relate to cultivation requirements.
- Choice D (Colonization of gastral cells) is incorrect as it pertains to bacterial behavior, not cultivation needs.

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Allergies to sea food, eggs, etc are an example of:

  • A. Type 1 hypersensitivity reaction
  • B. Type 2 hypersensitivity reaction
  • C. Type 3 hypersensitivity reaction
  • D. Type 4 hypersensitivity reaction
Correct Answer: A

Rationale: The correct answer is A: Type 1 hypersensitivity reaction. In this type of reaction, allergens trigger the production of IgE antibodies, leading to mast cell and basophil degranulation and release of inflammatory mediators like histamine. This causes immediate allergic symptoms. Seafood and eggs are common allergens that can elicit this response.

B: Type 2 hypersensitivity reaction involves antibodies targeting cell surface or extracellular matrix antigens, leading to cell destruction or dysfunction. This is not the mechanism in seafood or egg allergies.

C: Type 3 hypersensitivity reaction involves immune complex deposition in tissues, leading to inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.

D: Type 4 hypersensitivity reaction is cell-mediated and involves T cells causing inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.

Virulence

  • A. Is the degree of pathogenicity
  • B. Of the microorganism is not a constant characteristic
  • C. Can be measured with LD50
  • D. All the answers are true
Correct Answer: D

Rationale: The correct answer is D because virulence refers to the degree of pathogenicity of a microorganism, which can vary and is not a constant characteristic. It can be measured using LD50, which is the lethal dose that kills 50% of the test population. Therefore, all the statements in options A, B, and C are true and collectively provide a comprehensive understanding of virulence.

Which of the following organisms produces toxins that target cholesterol?

  • A. Streptococcus pyogenes
  • B. Corynebacterium diphtheriae
  • C. Escherichia coli
  • D. Aeromonas hydrophila
Correct Answer: C

Rationale: Step 1: Escherichia coli is known to produce a toxin called colibactin that targets cholesterol.
Step 2: Colibactin disrupts cholesterol metabolism in host cells.
Step 3: This disruption can lead to various health issues.
Step 4: Streptococcus pyogenes produces different toxins, not specifically targeting cholesterol.
Step 5: Corynebacterium diphtheriae produces diphtheria toxin, not targeting cholesterol.
Step 6: Aeromonas hydrophila produces various toxins, but not known for targeting cholesterol.
Summary: Escherichia coli produces toxins that specifically target cholesterol, making it the correct choice over the other options.

Microscopic examination of a microbial culture revealed fusiform spore-forming microorganisms that get violet-blue Gram's stain. What microorganisms were revealed?

  • A. Clostridia
  • B. Streptococci
  • C. Spirochaete
  • D. Actinomycete
Correct Answer: A

Rationale: The correct answer is A: Clostridia. Fusiform spore-forming microorganisms that stain violet-blue with Gram's stain are characteristic of Clostridia. Clostridia are anaerobic, rod-shaped bacteria known for their ability to form spores and cause diseases such as tetanus and botulism.

Summary of other choices:
B: Streptococci are spherical, not fusiform, and typically do not form spores.
C: Spirochaete are spiral-shaped bacteria and do not typically form spores.
D: Actinomycete are filamentous bacteria that do not typically form spores and do not stain violet-blue with Gram's stain.

Which bacteria are known for their ability to fix nitrogen?

  • A. Bacillus cereus
  • B. Azotobacter species
  • C. Clostridium botulinum
  • D. Escherichia coli
Correct Answer: B

Rationale: The correct answer is B: Azotobacter species. Azotobacter are known for their ability to fix nitrogen through the process of nitrogen fixation, converting atmospheric nitrogen into a form that plants can use. Bacillus cereus is not known for nitrogen fixation. Clostridium botulinum is a bacterium that causes botulism and does not fix nitrogen. Escherichia coli is a common gut bacterium but does not have the ability to fix nitrogen. Thus, Azotobacter species is the correct choice based on its unique ability to fix nitrogen.

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