Microbiology Chapter 11 Test Bank

Microbiology Chapter 11 Test Bank Related

Review Microbiology Chapter 11 Test Bank related questions and content

A 4 year old child had Mantoux test. 60 hours after tuberculin introduction a focal skin hardening and redness 15 mm in diameter appeared. It was regarded as positive test. What type of hypersensitivity reaction is this test based upon?

  • A. Delayed-type hypersensitivity
  • B. Immune complex-mediated hypersensitivity
  • C. Complement-mediated cytotoxic hypersensitivity
  • D. Immediate hypersensitivity
Correct Answer: A

Rationale: The correct answer is A: Delayed-type hypersensitivity. The Mantoux test is a type IV hypersensitivity reaction, which is also known as delayed-type hypersensitivity. This reaction typically occurs 48-72 hours after exposure to an antigen, such as tuberculin in this case. The focal skin hardening and redness that appeared 60 hours after tuberculin introduction align with the timeline and characteristics of a delayed-type hypersensitivity reaction.

Summary:
- Choice A (Delayed-type hypersensitivity): Correct, as explained above.
- Choice B (Immune complex-mediated hypersensitivity): Incorrect, as this reaction involves immune complexes and typically presents with tissue damage and inflammation.
- Choice C (Complement-mediated cytotoxic hypersensitivity): Incorrect, as this reaction involves the activation of complement proteins leading to cell lysis.
- Choice D (Immediate hypersensitivity): Incorrect, as this reaction, such as in allergies, occurs within minutes to hours of exposure to an antigen and involves IgE-mediated mast

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Which one of the following statements about Rickettsiae is true?

  • A. They do not form spores, capsules and flagella
  • B. They have slim glycocalyx layer
  • C. They have bipolar fimbriae
  • D. All of the above
Correct Answer: D

Rationale: Rationale:
1. Rickettsiae are obligate intracellular bacteria, hence they do not form spores, capsules, or flagella.
2. They have a slim glycocalyx layer, aiding in attachment to host cells.
3. Bipolar fimbriae are structures that help in adhesion to host cells.
Therefore, all statements (A, B, and C) are true for Rickettsiae, making option D the correct answer. Other choices are incorrect as they do not accurately describe the characteristics of Rickettsiae.

The establishment and further spreading of an infectious disease within a new population is a process called:

  • A. emergence
  • B. adoption
  • C. inclusion
  • D. appearance
Correct Answer: A

Rationale: The correct answer is A: emergence. The term emergence refers to the process of a new infectious disease appearing and spreading within a population. It signifies the initial introduction and establishment of the disease in the new population.

Explanation for other choices:
B: Adoption does not accurately describe the process of a disease spreading within a new population.
C: Inclusion is not a term commonly used to describe the spread of infectious diseases.
D: Appearance is too vague and does not capture the complexity of the process of establishment and spreading of an infectious disease.

The cytoplasmic membrane of the eukaryotes, in contrast to the one of prokaryotes, has:

  • A. cellulose
  • B. starch
  • C. chitin
  • D. sterols
Correct Answer: D

Rationale: The correct answer is D: sterols. Eukaryotic cytoplasmic membranes contain sterols, such as cholesterol, which provide stability and regulate fluidity. This is a key characteristic that distinguishes them from prokaryotic membranes. Cellulose (A) is a component of plant cell walls, not the cytoplasmic membrane. Starch (B) is a carbohydrate used for energy storage in plants. Chitin (C) is a component of fungal cell walls and arthropod exoskeletons, not found in eukaryotic cytoplasmic membranes.

Gram (-) bacteria have basal structure consisting of:

  • A. 20-25% of all materials building the cell wall
  • B. 1-4% of all materials building the cell wall
  • C. 4-10% of all materials building the cell wall
  • D. 10-20% of all materials building the cell wall
Correct Answer: C

Rationale: The correct answer is C: 4-10% of all materials building the cell wall. Gram (-) bacteria have a thin peptidoglycan layer making up 4-10% of the cell wall. This is in contrast to Gram (+) bacteria which have a thicker peptidoglycan layer. Choice A is too high a percentage for Gram (-) bacteria. Choice B is too low as it would not provide enough structural support. Choice D is also too high and would not accurately reflect the composition of Gram (-) bacteria.

The tool of choice to observe living microorganisms is the

  • A. bright-field microscope
  • B. phase-contrast microscope
  • C. fluorescence microscope
  • D. electron microscope
Correct Answer: B

Rationale: The correct answer is B: phase-contrast microscope. This type of microscope is ideal for observing living microorganisms because it enhances the contrast of transparent specimens without the need for staining or fixing, allowing for clear visualization of internal structures and movements. Bright-field microscopes (A) are suitable for observing fixed and stained specimens, not living organisms. Fluorescence microscopes (C) are used to detect specific cellular components tagged with fluorescent markers, not ideal for observing overall morphology. Electron microscopes (D) use electron beams and are best for viewing detailed structures at high magnification, but are not suitable for observing living organisms due to the need for vacuum conditions.

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