Nokea
Bypass fume hoods belong to the group of
- A. general-purpose hoods.
- B. radioisotope hoods.
- C. perchloric acid hoods.
- D. biosafety cabinets.
Correct Answer: A
Rationale: The correct answer is A: general-purpose hoods. Bypass fume hoods are designed to handle a wide range of chemical fumes and vapors, making them suitable for various types of experiments and processes. They are not specifically designed for radioisotopes (B), perchloric acid (C), or biological materials (D). Therefore, A is the correct choice for bypass fume hoods.
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Which of the following bacteria are unable to synthesize ATP?
- A. Chlamydia
- B. Enterococci
- C. Rickettsia
- D. Staphylococci
Correct Answer: A
Rationale: The correct answer is A: Chlamydia. Chlamydia lacks the essential enzymes for ATP synthesis and relies on host cell ATP. Enterococci, Rickettsia, and Staphylococci possess the necessary enzymes for ATP synthesis through cellular respiration. Chlamydia's inability to synthesize ATP makes it dependent on the host cell for energy production, distinguishing it from the other bacteria listed.
When examining a patient presumptively diagnosed with food toxicoinfection, a doctor on duty has detected symptoms characteristic of botulism. The patient named the meals he ate the day before. What is the most probable cause of infection?
- A. Homemade canned meat
- B. Custard pastry from a private bakery
- C. Sour cream from a local dairy factory
- D. Strawberries from a suburban vegetable garden
Correct Answer: A
Rationale: The correct answer is A: Homemade canned meat. Botulism is caused by the Clostridium botulinum bacteria, which thrives in low-oxygen environments like improperly canned food. Homemade canned meat poses a higher risk of contamination as it may not have been processed correctly, allowing the bacteria to grow and produce toxins. Custard pastry, sour cream, and strawberries are less likely to cause botulism as they are not typically associated with the bacteria unless improperly handled or stored. Homemade canned meat is the most probable cause based on the characteristic symptoms of botulism and the conditions that favor the growth of Clostridium botulinum in canned food.
Adenoviruses have helical capsids:
- A. TRUE
- B. FALSE
- C. Both answers can be correct depending on the given situation
- D. None of the above
Correct Answer: B
Rationale: Step 1: Adenoviruses are known to have icosahedral capsids, not helical.
Step 2: Helical capsids are typically found in viruses like tobacco mosaic virus.
Step 3: Therefore, the statement that adenoviruses have helical capsids is FALSE.
Summary: A is incorrect as adenoviruses do not have helical capsids. C is incorrect as there is no situation where adenoviruses have helical capsids. D is incorrect as there is a clear correct answer, which is B.
Acute hemorrhagic cystitis may be due to:
- A. Parvovirus B19
- B. CMV
- C. Adenovirus
- D. Herpesvirus type 2
Correct Answer: C
Rationale: Rationale for choice C (Adenovirus) being correct:
1. Adenovirus is a common cause of acute hemorrhagic cystitis.
2. Adenovirus infects the bladder epithelium, leading to inflammation and bleeding.
3. Symptoms include hematuria and bladder pain.
4. Diagnosis is confirmed through viral culture or PCR testing.
Summary of why other choices are incorrect:
A: Parvovirus B19 - More commonly associated with erythema infectiosum (fifth disease) and aplastic anemia.
B: CMV - Known to cause congenital infections, mononucleosis, and retinitis, not typically associated with hemorrhagic cystitis.
D: Herpesvirus type 2 - Commonly causes genital herpes, but not typically associated with acute hemorrhagic cystitis.
While examining the feces of a patient with diarrhea, cysts with four nuclei were found. What protozoan is most likely causing the condition?
- A. Entamoeba histolytica
- B. Lamblia
- C. Trichomonas
- D. Balantidium
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This protozoan causes amoebiasis, which presents with symptoms like diarrhea. The cysts with four nuclei found in the feces are characteristic of Entamoeba histolytica. This protozoan is known to cause invasive infection, leading to tissue destruction and ulcers in the intestines. Lamblia (choice B) typically presents with cysts containing two nuclei. Trichomonas (choice C) is a sexually transmitted parasite and does not form cysts. Balantidium (choice D) is a ciliated protozoan that does not have four nuclei in its cyst form.