Nokea
When growing in artificial media, the number of bacteria increases in geometric progression via:
- A. Logarithmic phase
- B. Death (decline) phase
- C. Stationary phase
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Logarithmic phase. During this phase, bacteria multiply exponentially due to abundant nutrients and favorable conditions. The growth is rapid and follows a geometric progression. In contrast, the Death phase (choice B) occurs when nutrients are depleted, leading to a decline in bacterial numbers. The Stationary phase (choice C) is when growth equals death rates, resulting in a stable population size. Choice D is incorrect because the Logarithmic phase accurately describes the exponential growth pattern of bacteria in artificial media.
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Which bacterium is known as a common cause of hospital-acquired infections?
- A. Clostridium botulinum
- B. Staphylococcus aureus
- C. Treponema pallidum
- D. Mycobacterium leprae
Correct Answer: B
Rationale: The correct answer is B: Staphylococcus aureus. This bacterium is known as a common cause of hospital-acquired infections due to its ability to colonize the skin and mucous membranes of healthcare workers and patients. Staphylococcus aureus can cause various infections, including surgical site infections and bloodstream infections, in healthcare settings.
Rationale:
1. Clostridium botulinum is known for causing foodborne botulism, not hospital-acquired infections.
2. Treponema pallidum causes syphilis, which is primarily transmitted through sexual contact, not hospital settings.
3. Mycobacterium leprae causes leprosy, which is not commonly associated with hospital-acquired infections.
In summary, Staphylococcus aureus is the correct answer as it is a common cause of hospital-acquired infections due to its prevalence in healthcare environments, unlike the other choices which are not typically associated with hospital-acquired infections.
The cytoplasmic membrane of the eukaryotes, in contrast to the one of prokaryotes, has:
- A. cellulose
- B. starch
- C. chitin
- D. sterols
Correct Answer: D
Rationale: The correct answer is D: sterols. Eukaryotic cytoplasmic membranes contain sterols, such as cholesterol, which provide stability and regulate fluidity. This is a key characteristic that distinguishes them from prokaryotic membranes. Cellulose (A) is a component of plant cell walls, not the cytoplasmic membrane. Starch (B) is a carbohydrate used for energy storage in plants. Chitin (C) is a component of fungal cell walls and arthropod exoskeletons, not found in eukaryotic cytoplasmic membranes.
The specific antidote to botulinum toxin is:
- A. sodium bicarbonate
- B. antitoxin
- C. pralidoxime
- D. naloxone
Correct Answer: B
Rationale: The correct answer is B: antitoxin. Antitoxin is the specific antidote to botulinum toxin as it helps neutralize the toxin in the body. Sodium bicarbonate (A) is used to treat acidosis, pralidoxime (C) is used for organophosphate poisoning, and naloxone (D) is used for opioid overdose. Antitoxin directly targets and counteracts the botulinum toxin, making it the appropriate antidote in cases of botulism.
Many peptic ulcers are due to:
- A. Salmonella typhi
- B. Helicobacter pylori
- C. Shigella boydii
- D. Salmonella enterica
Correct Answer: B
Rationale: The correct answer is B, Helicobacter pylori. This bacterium is the main cause of peptic ulcers by damaging the protective lining of the stomach and duodenum. It secretes enzymes that weaken the mucosal barrier, allowing stomach acid to cause damage. Salmonella typhi (A) causes typhoid fever, not peptic ulcers. Shigella boydii (C) causes dysentery, not peptic ulcers. Salmonella enterica (D) causes food poisoning, not peptic ulcers. Therefore, the correct answer is B based on its direct association with peptic ulcer formation.
Laboratory diagnosis of Rotavirus infection includes
- A. Egg inoculation
- B. Sensitive laboratory animals
- C. Ascoli test
- D. Cell cultures
Correct Answer: D
Rationale: The correct answer is D: Cell cultures. Rotavirus diagnosis involves detecting viral antigens in stool samples using cell cultures. Cell cultures allow for the replication of the virus, facilitating its identification. A: Egg inoculation and B: Sensitive laboratory animals are not commonly used for Rotavirus diagnosis due to ethical concerns and practical limitations. C: Ascoli test is used for detecting specific proteins in serum, not for Rotavirus detection in stool samples. In summary, cell cultures are the most appropriate method for laboratory diagnosis of Rotavirus infection due to their ability to support viral replication and antigen detection.