Nokea
A child with a sore throat had a throat smear revealing Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Neisseria gonorrhoeae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. The presence of Gram-positive cocci in pairs with a capsule is characteristic of Streptococcus pneumoniae.
Step 1: Gram-positive cocci in pairs indicate a Streptococcus species.
Step 2: The presence of a capsule suggests S. pneumoniae specifically.
Summary:
B: Staphylococcus aureus is a Gram-positive cocci but does not typically present in pairs with a capsule.
C: Neisseria gonorrhoeae is a Gram-negative diplococcus, not a Gram-positive cocci.
D: Klebsiella pneumoniae is a Gram-negative rod, not a cocci.
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Which bacteria is responsible for causing the disease known as leprosy?
- A. Mycobacterium leprae
- B. Neisseria gonorrhoeae
- C. Streptococcus pneumoniae
- D. Clostridium perfringens
Correct Answer: A
Rationale: The correct answer is A: Mycobacterium leprae. This bacterium is responsible for causing leprosy. Mycobacterium leprae is a slow-growing bacterium that affects the skin and nerves, leading to the characteristic symptoms of leprosy. Neisseria gonorrhoeae is a sexually transmitted bacterium causing gonorrhea. Streptococcus pneumoniae causes pneumonia and other respiratory infections. Clostridium perfringens is associated with food poisoning and gas gangrene. Therefore, the correct answer is A because Mycobacterium leprae specifically causes leprosy, while the other choices are associated with different diseases.
Which bacteria produce endotoxins that can cause septic shock?
- A. Escherichia coli
- B. Salmonella enterica
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D. Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa all produce endotoxins that can lead to septic shock. Endotoxins are part of the outer membrane of Gram-negative bacteria and can trigger a systemic inflammatory response if released into the bloodstream. E. coli and Salmonella are common causes of bacterial infections that can lead to septic shock, while P. aeruginosa is a known opportunistic pathogen that can produce endotoxins. Therefore, all three bacteria can cause septic shock by releasing endotoxins. Choices A, B, and C are incorrect because each of these bacteria individually can produce endotoxins that contribute to the development of septic shock.
Which of the statements below IS NOT CORRECT
- A. an immunocompromised person has to be vaccinated with live vaccines with caution
- B. live vaccines to not revert to virulent form
- C. microbes with many serotypes are difficult to control with vaccination
- D. side effect to vaccination can occur
Correct Answer: B
Rationale: The correct answer is B because live vaccines can potentially revert to a virulent form, although this is extremely rare. This is due to the live attenuated virus in the vaccine potentially mutating back to a more dangerous form. Live vaccines are designed to be weakened but there is a small risk of reversion. Therefore, statement B is not correct.
A: This statement is correct as immunocompromised individuals may have adverse reactions to live vaccines due to their weakened immune system.
C: This statement is correct as microbes with many serotypes can make it challenging to develop a vaccine that covers all variations.
D: This statement is correct as side effects to vaccination, although usually mild and temporary, can occur in some individuals.
Which is NOT TRUE:
- A. Defense role of the skin is related to the low pH of the skin surface
- B. Defense role of the skin is related to activity of the skin macrophages
- C. Defense role of the skin is related to secretion
- D. Defense role of skin is related to lysozyme activity
Correct Answer: D
Rationale: The correct answer is D because the defense role of the skin is not related to lysozyme activity. Lysozyme is an enzyme found in tears, saliva, and mucus, not specifically in the skin. The skin's defense role is primarily related to its physical barrier function, low pH creating an acidic environment that inhibits microbial growth, secretion of antimicrobial peptides, and the activity of skin macrophages that phagocytose pathogens. Choices A, B, and C are true statements as they correctly describe different aspects of the skin's defense mechanisms.
The net gain of ATP molecules after the breakdown of one glucose molecule in glycolysis is
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: The correct answer is B (2). During glycolysis, one glucose molecule is broken down into two molecules of pyruvate. In this process, a net gain of 2 ATP molecules is produced through substrate-level phosphorylation. Specifically, ATP is generated during the conversion of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate and during the conversion of phosphoenolpyruvate to pyruvate. The other choices are incorrect because the net gain of ATP molecules in glycolysis is not 1, 3, or 4; it is 2 based on the specific enzymatic reactions involved in the pathway.