Another term for spontaneous generation is __________.
- A. biogenesis
- B. abiogenesis
- C. evolution
- D. spontaneity
Correct Answer: B
Rationale: The correct answer is B: abiogenesis. Spontaneous generation refers to the idea that living organisms can arise from non-living matter, which was disproven by Louis Pasteur. Abiogenesis specifically refers to the origin of life from non-living matter, making it synonymous with spontaneous generation. Biogenesis (A) is the principle that living organisms only come from other living organisms. Evolution (C) is the process of gradual change in species over time. Spontaneity (D) refers to happening without external cause and is not directly related to the concept of spontaneous generation.
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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.
A woman who was infected with toxoplasmosis during the pregnancy has a child with multiple congenital defects. This is a result of:
- A. Teratogenesis
- B. Cancerogenesis
- C. Recombination
- D. Chemical mutogenesis
Correct Answer: A
Rationale: The correct answer is A: Teratogenesis. Teratogenesis refers to the process of abnormal development of the fetus leading to congenital defects due to exposure to harmful agents during pregnancy. In this case, toxoplasmosis infection during pregnancy can lead to teratogenesis, causing multiple congenital defects in the child. Other choices are incorrect because B: Cancerogenesis refers to the process of cancer formation, C: Recombination is a genetic process unrelated to congenital defects, and D: Chemical mutagenesis refers to mutations caused by chemical agents, not necessarily congenital defects.
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.
Shigella sonnei can escape phagocytic clearance by which mechanism?
- A. Lysis of phagosome and replication in cytoplasm
- B. capsule-mediated inhibition of phagocytosis
- C. Inhibition of phagosome/lysosome fusion
- D. inhibition of opsonization mediated by protein A
Correct Answer: A
Rationale: The correct answer is A because Shigella sonnei escapes phagocytic clearance by lysing the phagosome and replicating in the cytoplasm. This allows the bacterium to avoid being destroyed by the acidic environment and enzymes in the phagolysosome. Choice B is incorrect as Shigella does not have a capsule. Choice C is incorrect because Shigella actually induces phagosome-lysosome fusion to facilitate its escape. Choice D is incorrect as protein A is a component of Staphylococcus aureus, not Shigella sonnei.
A patient consulted a dentist about itching and burning in the oral cavity; high temperature. The patient was diagnosed with trichomonal gingivostomatitis. What drug should be chosen for his treatment?
- A. Metronidazole
- B. Ampicillin
- C. Gentamicin sulfate
- D. Nystatin
Correct Answer: A
Rationale: Step 1: Trichomonal gingivostomatitis is caused by the parasite Trichomonas tenax.
Step 2: Metronidazole is the drug of choice for treating infections caused by anaerobic organisms like Trichomonas.
Step 3: Metronidazole effectively targets and eliminates Trichomonas parasites in the oral cavity.
Step 4: Therefore, the correct drug choice for treating trichomonal gingivostomatitis is Metronidazole.
Summary:
- Ampicillin (B) is an antibiotic effective against Gram-positive bacteria, not parasites.
- Gentamicin sulfate (C) is an antibiotic used for bacterial infections, not parasitic infections.
- Nystatin (D) is an antifungal medication used for treating fungal infections, not parasitic infections like trichomonal gingivostomatitis.