Nokea
A laboratory received a sample of water used in drug production for sanitary and viral analysis. What group of viruses will indicate fecal contamination of water and thus the need for its additional purification?
- A. Picornaviridae
- B. Herpesviridae
- C. Flaviviridae
- D. Retroviridae
Correct Answer: A
Rationale: The correct answer is A: Picornaviridae. Picornaviruses, such as enteroviruses, are commonly found in the feces of infected individuals. Therefore, their presence in water indicates fecal contamination and the need for additional purification.
B: Herpesviridae are not typically associated with fecal contamination.
C: Flaviviridae are mainly transmitted through arthropods like mosquitoes, not fecal contamination.
D: Retroviridae, including HIV, are not typically excreted in high levels in feces and are not indicators of fecal contamination.
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Mycobacteria have in their cell walls:
- A. High amount of polysaccharides
- B. High amount of lipids
- C. High amount of mycolic acids
- D. High amount of proteins
Correct Answer: C
Rationale: The correct answer is C: High amount of mycolic acids. Mycobacteria are characterized by their unique cell wall composition, which includes a high amount of mycolic acids. Mycolic acids provide the bacteria with resistance to environmental stresses and are crucial for their pathogenicity. Polysaccharides (A) are not a prominent component of mycobacterial cell walls. While lipids (B) are present in mycobacterial cell walls, mycolic acids are the predominant lipid. Proteins (D) are also present but are not the defining feature of mycobacterial cell walls. Therefore, the correct answer is C due to the significant role mycolic acids play in the structure and function of mycobacterial cell walls.
Lytic cycle of the bacteriophages differs from the lysogenic one by
- A. lysogenetic phages destroy the host cell when leaving the cell
- B. lytic phages do not destroy the host cell
- C. do not differ
- D. none of them
Correct Answer: A
Rationale: The correct answer is A because in the lytic cycle, the bacteriophage destroys the host cell upon release, whereas in the lysogenic cycle, the phage integrates its DNA into the host genome without killing the host immediately. This integration may lead to the destruction of the host cell at a later stage. Choice B is incorrect as lytic phages do destroy the host cell. Choice C is incorrect as the two cycles have distinct mechanisms. Choice D is incorrect as there are clear differences between the lytic and lysogenic cycles.
The bacteria that cause Lyme disease is:
- A. Treponema pallidum
- B. Borrelia burgdorferi
- C. Leptospira interrogans
- D. Rickettsia rickettsii
Correct Answer: B
Rationale: The correct answer is B: Borrelia burgdorferi. Borrelia burgdorferi is the bacteria responsible for causing Lyme disease. It is transmitted to humans through the bite of infected black-legged ticks. Treponema pallidum causes syphilis, Leptospira interrogans causes leptospirosis, and Rickettsia rickettsii causes Rocky Mountain spotted fever. Borrelia burgdorferi is specifically associated with Lyme disease due to its transmission through tick bites and the characteristic symptoms it causes.
Matrix formed outside the plasma membrane is referred to as:
- A. cytoplasm
- B. glycocalyx
- C. exoplasm
- D. cell wall
Correct Answer: B
Rationale: The correct answer is B: glycocalyx. The glycocalyx is a matrix formed outside the plasma membrane that consists of glycoproteins and glycolipids. It plays crucial roles in cell-cell recognition, protection, and immune response. Cytoplasm (A) is the gel-like substance inside the cell, not outside. Exoplasm (C) is not a recognized term in biology. Cell wall (D) is a rigid structure found in plant cells, not outside the plasma membrane in all cells.
A patient with pulmonary tuberculosis is prescribed the most effective antituberculosis antibiotic. Name this drug:
- A. Tetracycline
- B. Furasolidone
- C. Rifampicin
- D. Bactrim (Co-trimoxazole)
Correct Answer: C
Rationale: Rifampicin is the correct answer because it is a first-line antibiotic for treating pulmonary tuberculosis. It has excellent bactericidal activity and penetrates well into lung tissues where the infection is located. Rifampicin is also known for preventing the development of resistance. Tetracycline (A) and Furasolidone (B) are not commonly used for tuberculosis treatment. Bactrim (D) is a combination of sulfamethoxazole and trimethoprim, not effective for tuberculosis treatment.