Nokea
Genus Rickettsia representatives are characterized by:
- A. Gram-positive cell wall
- B. High resistance to external environment factors
- C. Intracellular parasitism
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C: Intracellular parasitism. Genus Rickettsia representatives are known for their ability to live and replicate inside the host's cells, making them obligate intracellular parasites. This characteristic distinguishes them from other bacteria.
A: Gram-positive cell wall is incorrect because Rickettsia have a gram-negative cell wall.
B: High resistance to external environment factors is incorrect because Rickettsia are sensitive to environmental conditions and require specific host cells for survival.
D: None of the above is incorrect because Rickettsia do exhibit the characteristic of intracellular parasitism.
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All bacteria are __________ cells.
- A. eukaryotic
- B. prokaryotic
- C. diploid
- D. haploid
Correct Answer: B
Rationale: The correct answer is B: prokaryotic. Bacteria are prokaryotic cells because they lack a true nucleus and membrane-bound organelles. They have a simple cell structure with genetic material floating freely in the cytoplasm. Choice A (eukaryotic) is incorrect because eukaryotic cells have a nucleus and membrane-bound organelles. Choice C (diploid) is incorrect as bacteria do not have a defined ploidy level like diploid organisms do. Choice D (haploid) is also incorrect as bacteria do not have a true haploid or diploid state due to their lack of a defined nucleus.
Which is correct for bacterial growth?
- A. Most of the bacteria can grow in absence or in presence of oxygen
- B. All bacteria grow in absence of oxygen
- C. All bacteria are microaerophiles
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because most bacteria can grow in both the presence and absence of oxygen. Some bacteria are aerobic and require oxygen for growth, while others are anaerobic and can grow in the absence of oxygen. Choice B is incorrect because not all bacteria grow in the absence of oxygen. Choice C is incorrect because not all bacteria are microaerophiles, which are bacteria that require a low level of oxygen for growth. Choice D is incorrect because most bacteria exhibit flexibility in their oxygen requirements.
The most common cause of cystitis (after Escherichia coli) in healthy sexually active women is:
- A. Staphylococcus saprophyticus
- B. Proteus mirabilis
- C. Pseudomonas aeruginosa
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus saprophyticus. This bacterium is the second most common cause of cystitis in healthy sexually active women after E. coli. Staphylococcus saprophyticus is commonly found in the gastrointestinal and genital areas. It has a unique ability to adhere to uroepithelial cells, making it a common pathogen in urinary tract infections. Proteus mirabilis is more commonly associated with complicated UTIs, especially in catheterized patients. Pseudomonas aeruginosa is more commonly seen in hospitalized or immunocompromised patients. Klebsiella pneumoniae is typically associated with UTIs in elderly patients or those with structural abnormalities in the urinary tract.
A patient with pneumonia had sputum cultured, revealing Gram-negative rods. The bacteria were lactose fermenters and produced green colonies on MacConkey agar. What is the most likely causative agent?
- A. Escherichia coli
- B. Klebsiella pneumoniae
- C. Pseudomonas aeruginosa
- D. Proteus mirabilis
Correct Answer: A
Rationale: Rationale:
1. Gram-negative rods suggest Enterobacteriaceae family.
2. Lactose fermenters narrow down to E. coli.
3. Green colonies on MacConkey agar indicate acid production.
4. E. coli is a common cause of pneumonia.
Therefore, the most likely causative agent is Escherichia coli. Other choices are incorrect as Klebsiella is non-lactose fermenter, Pseudomonas is oxidase-positive, and Proteus is non-lactose fermenter.
Which of the following bacteria are capable of surviving in low-oxygen environments?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Obligate aerobes
- D. Microaerophiles
Correct Answer: B
Rationale: The correct answer is B: Facultative anaerobes. Facultative anaerobes can survive in both oxygen-rich and oxygen-poor environments by switching between aerobic and anaerobic metabolism. They have the flexibility to use oxygen if present but can also ferment in the absence of oxygen. Obligate anaerobes (A) cannot survive in the presence of oxygen, obligate aerobes (C) require oxygen for survival, and microaerophiles (D) require low levels of oxygen for growth, unlike facultative anaerobes.