Nokea
Which of the following cell organelles contain digestive enzymes?
- A. lysosomes
- B. chloroplasts
- C. peroxisomes
- D. peroxisomes
Correct Answer: C
Rationale: The correct answer is C: peroxisomes. Peroxisomes contain enzymes involved in breaking down fatty acids and detoxifying harmful substances. They do not contain digestive enzymes. Lysosomes contain digestive enzymes involved in breaking down waste materials. Chloroplasts are involved in photosynthesis and do not contain digestive enzymes. Mitochondria are involved in energy production and do not contain digestive enzymes. Therefore, the correct answer is peroxisomes.
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What are the two main targets currently used in anti-HIV therapy?
- A. Reverse transcriptase and something integrase
- B. Reverse transcriptase and protease
- C. Protease and integrase
- D. Viral glycoproteins gp120 and gp41
Correct Answer: B
Rationale: The correct answer is B: Reverse transcriptase and protease. Reverse transcriptase converts viral RNA into DNA, a crucial step in viral replication. Protease is responsible for cleaving viral polyproteins into functional proteins. Targeting both enzymes disrupts viral replication. Choice A is incorrect as integrase is not a main target in current therapy. Choice C is incorrect because protease is targeted along with reverse transcriptase, not integrase. Choice D is incorrect as targeting viral glycoproteins is not a main strategy in anti-HIV therapy.
For shigella is true:
- A. They produce hydrogen sulfide
- B. They ferment lactose
- C. They are nonmotile
- D. All of them are mannitol positive
Correct Answer: C
Rationale: Step-by-step rationale:
1. Shigella is a nonmotile bacterium.
2. This lack of motility is a key characteristic used to differentiate it from other enteric bacteria.
3. Nonmotile nature of Shigella helps it to cause infections by invading the intestinal epithelial cells.
4. Therefore, choice C is correct as Shigella is indeed nonmotile.
Summary:
A: Incorrect - Shigella does not produce hydrogen sulfide.
B: Incorrect - Shigella does not ferment lactose.
D: Incorrect - Shigella is not mannitol positive.
A sputum smear from a patient with pneumonia revealed Gram-positive diplococci with a capsule. What is the most likely 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. This bacterium is a common cause of pneumonia and is characterized by Gram-positive diplococci with a capsule. The presence of a capsule helps the bacterium evade the immune system and contributes to its virulence. Klebsiella pneumoniae (B) is a Gram-negative bacterium and does not typically have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus and is associated with meningitis, not pneumonia. Staphylococcus aureus (D) is a Gram-positive bacterium, but it does not typically present as diplococci with a capsule in a sputum smear from a pneumonia patient.
A patient presents with a history of diarrhea of several weeks duration. Which of the following may be the cause?
- A. Yersinia enterocolitica
- B. Bordetella pertussis
- C. Neisseria meningitidis
- D. Corynebacterium diphtheria
Correct Answer: A
Rationale: Rationale:
- Yersinia enterocolitica is a common cause of diarrhea due to contaminated food or water.
- It typically presents with symptoms such as abdominal pain, fever, and diarrhea.
- The other choices are unlikely causes of prolonged diarrhea, as Bordetella pertussis causes whooping cough, Neisseria meningitidis causes meningitis, and Corynebacterium diphtheria causes diphtheria.
Infection caused by the genus Candida can be successfully treated with:
- A. Penicillins
- B. Cephalosporins of third generation
- C. Nystatin
- D. None of the above
Correct Answer: C
Rationale: Step-by-step rationale for why choice C (Nystatin) is the correct answer:
1. Nystatin is an antifungal medication specifically effective against Candida infections.
2. Candida is a type of fungus, not a bacteria targeted by penicillins (choice A) or cephalosporins (choice B).
3. Nystatin works by disrupting the fungal cell membrane, leading to its death.
4. Choice D (None of the above) is incorrect as Nystatin is a suitable treatment option for Candida infections.