Nokea
What is the function of bacterial flagella?
- A. Protein synthesis
- B. Motility
- C. Adhesion to surfaces
- D. DNA replication
Correct Answer: B
Rationale: The correct answer is B: Motility. Bacterial flagella function in providing motility to bacteria, allowing them to move towards nutrients or away from harmful substances. Flagella are long, whip-like appendages that rotate to propel the bacteria through their environment.
Incorrect choices:
A: Protein synthesis - Bacterial flagella are not involved in protein synthesis.
C: Adhesion to surfaces - While some bacteria use flagella for attachment, their main function is not adhesion.
D: DNA replication - Flagella do not play a role in DNA replication, which occurs in the bacterial cell's nucleus.
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Which bacteria produce exotoxins that damage host tissues?
- A. Clostridium tetani and Bacillus anthracis
- B. Escherichia coli and Pseudomonas aeruginosa
- C. Streptococcus pneumoniae and Listeria monocytogenes
- D. Salmonella typhi and Mycobacterium tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Clostridium tetani and Bacillus anthracis. Both bacteria produce exotoxins that damage host tissues. Clostridium tetani produces tetanospasmin, which causes muscle rigidity in tetanus. Bacillus anthracis produces anthrax toxins, leading to tissue damage and systemic effects.
Explanation:
- Choice B (Escherichia coli and Pseudomonas aeruginosa) primarily cause infections through other mechanisms and do not produce exotoxins that damage host tissues.
- Choice C (Streptococcus pneumoniae and Listeria monocytogenes) are known for causing infections but not primarily through exotoxins that damage host tissues.
- Choice D (Salmonella typhi and Mycobacterium tuberculosis) cause diseases through different mechanisms and do not produce exotoxins that directly damage host tissues.
Microscopic examination of a patient's duodenal contents revealed protozoa with two nuclei, four flagella, and a ventral adhesive disc. What is the likely causative agent?
- A. Giardia lamblia
- B. Leishmania donovani
- C. Entamoeba coli
- D. Trypanosoma gambiense
Correct Answer: A
Rationale: The correct answer is A: Giardia lamblia. This protozoan matches the description of the causative agent because it has two nuclei, four flagella, and a ventral adhesive disc. Giardia lamblia is commonly found in the duodenum and causes giardiasis. The other choices can be eliminated because Leishmania donovani causes visceral leishmaniasis, not the described symptoms. Entamoeba coli is a non-pathogenic amoeba found in the large intestine. Trypanosoma gambiense causes African trypanosomiasis and is transmitted by the tsetse fly, not matching the described characteristics.
Which of the following scientists performed the first vaccination against smallpox?
- A. Pasteur
- B. Jenner
- C. Semmelweis
- D. Koch
Correct Answer: B
Rationale: The correct answer is B: Jenner. Edward Jenner performed the first vaccination against smallpox in 1796 by using cowpox virus to immunize individuals. He observed that milkmaids who had contracted cowpox did not get smallpox, leading to the development of the smallpox vaccine. Pasteur is known for germ theory, Semmelweis for handwashing in healthcare, and Koch for identifying the causative agents of diseases. However, none of them performed the first smallpox vaccination like Jenner.
Which bacteria are responsible for causing the disease known as 'whooping cough'?
- A. Bordetella pertussis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. Mycobacterium tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Bordetella pertussis. Bordetella pertussis is the bacterium responsible for causing whooping cough, also known as pertussis. It produces toxins that damage the respiratory tract, leading to severe coughing fits. Haemophilus influenzae, Streptococcus pneumoniae, and Mycobacterium tuberculosis are not associated with whooping cough. Haemophilus influenzae can cause respiratory infections but not whooping cough. Streptococcus pneumoniae is known for causing pneumonia, and Mycobacterium tuberculosis causes tuberculosis, both different from whooping cough. Therefore, the correct answer is A as it is the specific bacterium linked to the disease in question.
Fudrjant fern of injection is:
- A. Continuous infection with long incubation period
- B. Chronic infection with short incubation period
- C. Immediate infection with very short incubation period
- D. ‘Sleeping' infection with infection-carrying
Correct Answer: A
Rationale: The correct answer is A: Continuous infection with long incubation period. Fudrjant fern of injection is a term used to describe an infection that is continuously present in the body after being introduced through injection. The long incubation period refers to the time between the injection and when symptoms of the infection become apparent. This choice is correct as it accurately describes the characteristics of fudrjant fern of injection.
Choice B is incorrect because chronic infections typically have a long duration, not a short incubation period. Choice C is incorrect as immediate infections would not have a long incubation period. Choice D is incorrect because a 'sleeping' infection implies a dormant state, not continuous presence in the body as seen in fudrjant fern of injection.