Nokea
The antigen receptors on the surface of B-lymphocytes are made by proteins:
- A. TRUE
- B. FALSE
- C. Both answers can be correct depending on the given situation
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: TRUE. B-lymphocyte antigen receptors are made by proteins called immunoglobulins. These proteins are essential for recognizing and binding to specific antigens. They play a crucial role in the immune response. Choice B is incorrect because B-lymphocyte antigen receptors are indeed made by proteins. Choice C is incorrect as well because in this case, the correct answer is that the receptors are made by proteins. Choice D is also incorrect as the receptors are made by proteins.
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Which of the following bacteria is responsible for causing syphilis?
- A. Treponema pallidum
- B. Neisseria gonorrhoeae
- C. Chlamydia trachomatis
- D. Escherichia coli
Correct Answer: A
Rationale: Step 1: Treponema pallidum is a spirochete bacterium known to cause syphilis.
Step 2: It is sexually transmitted and can cause various stages of disease.
Step 3: Neisseria gonorrhoeae causes gonorrhea, not syphilis.
Step 4: Chlamydia trachomatis causes chlamydia, not syphilis.
Step 5: Escherichia coli is a common gut bacterium and not responsible for syphilis. Treponema pallidum is the correct answer as it is the specific bacterium known to cause syphilis.
A fecal smear from a patient with chronic diarrhea revealed cysts with four nuclei. What is the most likely causative agent?
- A. Entamoeba histolytica
- B. Balantidium coli
- C. Giardia lamblia
- D. Trichomonas hominis
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This protozoan parasite causes amoebic dysentery and is characterized by cysts with four nuclei in fecal smears. It is commonly associated with chronic diarrhea. Balantidium coli (B) presents with large ciliated trophozoites, not cysts. Giardia lamblia (C) has trophozoites with flagella and causes giardiasis, not cysts with four nuclei. Trichomonas hominis (D) typically has a pear-shaped trophozoite and is not associated with cysts with four nuclei.
Which type of bacteria is responsible for causing tuberculosis?
- A. Streptococcus pyogenes
- B. Mycobacterium tuberculosis
- C. Escherichia coli
- D. Bacillus anthracis
Correct Answer: B
Rationale: The correct answer is B: Mycobacterium tuberculosis. Mycobacterium tuberculosis is the bacteria responsible for causing tuberculosis. This bacterium has unique cell wall components that make it resistant to the body's immune defenses, allowing it to survive and multiply within the host. Streptococcus pyogenes (Choice A), Escherichia coli (Choice C), and Bacillus anthracis (Choice D) are not associated with tuberculosis. Streptococcus pyogenes is known for causing strep throat and skin infections, Escherichia coli is commonly involved in gastrointestinal infections, and Bacillus anthracis causes anthrax.
Which of the following bacteria can cause urinary tract infections (UTIs)?
- A. Escherichia coli
- B. Salmonella enterica
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D: All of the above. Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa are all known to cause urinary tract infections (UTIs) in humans. E. coli is the most common cause of UTIs, accounting for about 80-85% of cases. S. enterica and P. aeruginosa are less common but can still infect the urinary tract under certain circumstances. Therefore, all three bacteria can potentially cause UTIs, making option D the correct choice. Choices A, B, and C are incorrect because they do not cover the full range of bacteria known to cause UTIs.
Generalization of an intestine infection can be seen in
- A. Salmonella typhi
- B. Shigella flexneri
- C. Helicobacter pylori
- D. None of the above
Correct Answer: A
Rationale: Rationale:
1. Salmonella typhi causes typhoid fever, which can lead to intestinal infections.
2. Shigella flexneri causes dysentery, primarily affecting the colon.
3. Helicobacter pylori causes stomach ulcers, not intestine infections.
Summary:
A is correct as Salmonella typhi causes intestine infection. B and C are incorrect as they cause different gastrointestinal issues. D is incorrect as A is a valid choice.