Nokea
The role of pili in bacteria is:
- A. protection from desiccation
- B. motility
- C. adhesion to surfaces and conjugation
- D. spore formation
Correct Answer: C
Rationale: The correct answer is C: adhesion to surfaces and conjugation. Pili are hair-like structures on the surface of bacteria that help them adhere to surfaces and facilitate the transfer of genetic material during conjugation. This is essential for bacterial survival and reproduction. Choice A is incorrect because protection from desiccation is typically associated with other structures like capsules. Choice B is incorrect as motility in bacteria is usually facilitated by flagella. Choice D is incorrect as spore formation involves the formation of specialized structures, not pili.
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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.
Which of the following bacteria is known for causing the disease known as leprosy?
- A. Mycobacterium leprae
- B. Clostridium perfringens
- C. Streptococcus pneumoniae
- D. Neisseria gonorrhoeae
Correct Answer: A
Rationale: Step-by-step rationale:
1. Mycobacterium leprae is the correct answer as it is the bacteria known to cause leprosy.
2. Clostridium perfringens is incorrect as it is associated with gas gangrene.
3. Streptococcus pneumoniae is incorrect as it is commonly linked to pneumonia and meningitis.
4. Neisseria gonorrhoeae is incorrect as it causes gonorrhea, a sexually transmitted infection.
In summary, Mycobacterium leprae is the only bacteria among the choices specifically known to cause leprosy, making it the correct answer.
How do people get infected with diphtheria
- A. by swimming in contaminated water
- B. by transmission
- C. by droplets and physical contact
- D. by contaminated food
Correct Answer: C
Rationale: The correct answer is C because diphtheria is primarily spread through respiratory droplets and physical contact with an infected person. The bacteria responsible for diphtheria is transmitted through coughing, sneezing, or sharing personal items. Swimming in contaminated water (A) does not spread diphtheria. Transmission (B) is a broad term and does not specifically address the mode of transmission for diphtheria. Contaminated food (D) is not a typical route of diphtheria transmission. Therefore, option C is the most accurate choice based on the known mode of transmission for diphtheria.
Family Retroviridae
- A. are helical enveloped viruses
- B. Their capsid consists of two copies o ssRNA (-)
- C. are helical, non-enveloped viruses
- D. are with complex type of symmetry
Correct Answer: B
Rationale: The correct answer is B because retroviruses, including those in the Family Retroviridae, have a capsid consisting of two copies of single-stranded RNA (ssRNA). This is a defining characteristic of retroviruses, which use reverse transcriptase to convert their ssRNA into DNA. This DNA is then integrated into the host cell's genome. Choices A, C, and D are incorrect because Family Retroviridae viruses are not helical non-enveloped viruses (C), they are not helical enveloped viruses (A), and they do not have a complex type of symmetry (D).
Acute febrile pharyngitis and pharyngoconjunctival fever are often the clinical presentation of which viral infection:
- A. VZV
- B. Measles virus
- C. Rubella virus
- D. Adenovirus
Correct Answer: D
Rationale: The correct answer is D: Adenovirus. Adenovirus commonly causes acute febrile pharyngitis and pharyngoconjunctival fever. Adenovirus is known to cause respiratory infections and can present with symptoms such as sore throat, fever, and conjunctivitis. VZV (Varicella-Zoster Virus) causes chickenpox and shingles, not these specific symptoms. Measles virus causes a systemic illness with characteristic rash, not typically pharyngitis. Rubella virus causes a mild febrile illness with rash, but not pharyngitis. Therefore, based on the clinical presentation described, adenovirus is the most likely cause.