Nokea
The development of polioviruses on cell cultures is characterized by:
- A. Cytopathic effect
- B. Cytotoxic effect
- C. Cytolytic effect
- D. They Don't Change The Cell Cultures
Correct Answer: A
Rationale: The correct answer is A: Cytopathic effect. This is because polioviruses cause visible changes in infected cells, leading to cell damage and death, known as cytopathic effect. This is a key characteristic of viral infection. Choice B (Cytotoxic effect) is incorrect as it refers to the toxicity of a substance to cells, not the specific effect of polioviruses. Choice C (Cytolytic effect) is incorrect as it specifically refers to cell lysis, which is not the primary mechanism of poliovirus infection. Choice D (They Don't Change The Cell Cultures) is incorrect because polioviruses do indeed cause changes in cell cultures due to their cytopathic effect.
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Bacillus intoxication is caused by:
- A. Bacillus subtilis
- B. Bacillus thuringiensis
- C. Bacillus anthracis
- D. Bacillus cereus
Correct Answer: D
Rationale: The correct answer is D: Bacillus cereus. Bacillus intoxication is typically caused by Bacillus cereus, which is a common foodborne pathogen. This bacterium produces toxins that can lead to gastrointestinal illness when ingested. Bacillus subtilis (A) and Bacillus thuringiensis (B) are not known to cause intoxication in humans. Bacillus anthracis (C) causes anthrax, not intoxication. Therefore, Bacillus cereus is the correct choice for Bacillus intoxication.
Which bacteria is commonly associated with urinary tract infections (UTIs)?
- A. Escherichia coli
- B. Clostridium botulinum
- C. Staphylococcus aureus
- D. Bacillus cereus
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. E. coli is commonly associated with UTIs due to its ability to colonize the urinary tract. It possesses adhesins that allow it to attach to the bladder wall, causing infection. E. coli is also a common inhabitant of the intestinal tract, making it easily able to migrate to the urinary system.
Explanation of incorrect choices:
B: Clostridium botulinum - This bacterium causes botulism, a rare foodborne illness, not UTIs.
C: Staphylococcus aureus - Often associated with skin infections and abscesses, not UTIs.
D: Bacillus cereus - Known for causing food poisoning, not UTIs.
A smear of a patient's sputum suspected for tuberculosis was prepared and stained. The smear showed red bacilli against a blue background. What staining method was used?
- A. Ziehl-Neelsen
- B. Gram
- C. Giemsa
- D. Neisser
Correct Answer: A
Rationale: The correct answer is A: Ziehl-Neelsen staining method. This method is used to detect acid-fast bacteria like Mycobacterium tuberculosis. Step-by-step rationale: 1. Acid-fast bacteria resist decolorization with acid-alcohol. 2. The red bacilli seen in the smear indicate acid-fast bacteria. 3. Ziehl-Neelsen stain uses carbol fuchsin to stain acid-fast bacteria red. 4. The blue background is likely the counterstain methylene blue. Incorrect choices: B: Gram stain is for categorizing bacteria into Gram-positive or Gram-negative, not specific for acid-fast bacteria. C: Giemsa stain is used for blood films and detecting parasites, not acid-fast bacteria. D: Neisser stain is not a standard microbiological staining method.
The papillary layer of the skin is part of the:
- A. epidermis
- B. dermis
- C. hypodermis
- D. subcutaneous layer
Correct Answer: B
Rationale: The correct answer is B: dermis. The papillary layer is located in the dermis, specifically at the junction with the epidermis. It contains capillaries, lymphatics, and sensory receptors, contributing to the skin's strength and elasticity. The epidermis (choice A) is the outermost layer of the skin, while the hypodermis (choice C) and subcutaneous layer (choice D) are deeper layers beneath the dermis, primarily composed of fat cells and connective tissue. Therefore, the papillary layer is part of the dermis, making choice B the correct answer.
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.