Nokea
Which of the following organelles contain oxidative enzymes capable of oxidizing toxic substances?
- A. peroxisomes
- B. lysosomes
- C. lysosomes
- D. peroxisomes
Correct Answer: D
Rationale: The correct answer is D: peroxisomes. Peroxisomes contain oxidative enzymes, such as catalase and peroxidase, that are capable of oxidizing toxic substances. These enzymes help detoxify harmful molecules by breaking them down into harmless products. Lysosomes (choices B and C) contain hydrolytic enzymes for breaking down cellular waste, not oxidative enzymes. Therefore, the correct choice is peroxisomes due to their specific function in detoxification through oxidation reactions.
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Microscopy of a sputum smear from a pneumonia patient revealed Gram-positive diplococci with pointed ends surrounded by a capsule. What is the causative agent?
- A. Streptococcus pneumoniae
- B. Klebsiella pneumoniae
- C. Neisseria meningitidis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae.
1. Gram-positive diplococci with pointed ends: characteristic morphology of Streptococcus pneumoniae.
2. Surrounded by a capsule: S. pneumoniae is encapsulated, important for virulence.
3. Klebsiella pneumoniae (B) is a Gram-negative rod, Neisseria meningitidis (C) is a Gram-negative diplococcus, and Staphylococcus aureus (D) is a Gram-positive cocci in clusters, not diplococci.
Which bacteria are capable of producing an exotoxin that causes severe diarrhea?
- A. Escherichia coli
- B. Clostridium botulinum
- C. Vibrio cholerae
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D because all three bacteria listed are capable of producing exotoxins that can cause severe diarrhea. Escherichia coli can produce toxins that lead to diarrhea. Clostridium botulinum produces a neurotoxin causing botulism, which can also result in diarrhea. Vibrio cholerae is known for producing cholera toxin, a potent exotoxin that causes severe watery diarrhea. The other choices are incorrect because each bacterium listed is capable of producing a toxin that can cause diarrhea.
Which of the following bacteria is known for causing Lyme disease?
- A. Borrelia burgdorferi
- B. Clostridium difficile
- C. Streptococcus pneumoniae
- D. Mycobacterium tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Borrelia burgdorferi. This bacterium is known for causing Lyme disease, which is transmitted through tick bites. Borrelia burgdorferi is specifically associated with Lyme disease due to its ability to infect and spread within the body, leading to a range of symptoms if left untreated.
Summary of incorrect choices:
B: Clostridium difficile - Known for causing gastrointestinal infections, not Lyme disease.
C: Streptococcus pneumoniae - Commonly causes pneumonia and other respiratory infections, not Lyme disease.
D: Mycobacterium tuberculosis - Causes tuberculosis, a respiratory disease, not Lyme disease.
On the base of the clinical data a child was diagnosed with atypical pneumonia resistant to the effects of beta-lactam antibiotics. The patient's sputum was cultured and incubated in a special medium, which resulted in growth of microorganisms forming microscopic colonies with a dense center (looking like fried eggs). What microorganism caused the disease?
- A. Mycoplasma pneumoniae
- B. Klebsiella pneumoniae
- C. Str. pneumoniae
- D. L. pneumophila
Correct Answer: A
Rationale: The correct answer is A: Mycoplasma pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia and is known to be resistant to beta-lactam antibiotics. The description of microorganisms forming microscopic colonies with a dense center resembling fried eggs is characteristic of Mycoplasma pneumoniae colonies seen on special media.
Summary of other choices:
B: Klebsiella pneumoniae is not typically associated with atypical pneumonia and does not exhibit the described colony morphology.
C: Streptococcus pneumoniae is not resistant to beta-lactam antibiotics and does not produce colonies with the described appearance.
D: Legionella pneumophila is associated with Legionnaires' disease, not atypical pneumonia, and does not form colonies resembling fried eggs.
For Parvovirus B19 is true that:
- A. Causes HBV
- B. Causes AIDS
- C. Causes erythema infectiosum
- D. Causes measles
Correct Answer: C
Rationale: The correct answer is C because Parvovirus B19 causes erythema infectiosum, also known as fifth disease. This virus primarily affects children and causes a distinctive red rash on the cheeks, arms, and legs. It is not associated with causing HBV (Hepatitis B Virus), AIDS, or measles. Parvovirus B19 specifically targets red blood cell precursors, leading to anemia in some cases. Understanding the characteristic clinical presentation and pathophysiology of the virus helps in selecting the correct answer.