Which type of bacteria have an outer membrane containing lipopolysaccharides (LPS)?
- A. Gram-positive bacteria
- B. Gram-negative bacteria
- C. Both Gram-positive and Gram-negative bacteria
- D. Neither Gram-positive nor Gram-negative bacteria
Correct Answer: B
Rationale: The correct answer is B: Gram-negative bacteria. Gram-negative bacteria have an outer membrane containing lipopolysaccharides (LPS). In the Gram staining technique, these bacteria appear pink/red due to the thin peptidoglycan layer, which allows the crystal violet stain to be washed out, revealing the safranin counterstain. Gram-positive bacteria (choice A) have a thick peptidoglycan layer but lack an outer membrane with LPS. Choice C is incorrect since only Gram-negative bacteria possess LPS in their outer membrane. Choice D is incorrect as all bacteria can be classified as either Gram-positive or Gram-negative based on their cell wall structure.
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The following viruses are referred to the Filoviridae family
- A. Lassa virus and lymphocytic choriomeningitis viruses
- B. Chikungunya virus and Sindbis virus
- C. Marburg virus and Ebola virus
- D. Crimean-Congo virus and Hantaan virus
Correct Answer: C
Rationale: The correct answer is C because Marburg virus and Ebola virus belong to the Filoviridae family. These viruses are characterized by their filamentous shape and are known to cause severe hemorrhagic fever in humans. Both viruses have caused outbreaks with high mortality rates.
Choice A (Lassa virus and lymphocytic choriomeningitis viruses) are not part of the Filoviridae family. They belong to the Arenaviridae family, which also includes viruses that cause hemorrhagic fevers.
Choice B (Chikungunya virus and Sindbis virus) are arboviruses belonging to the Togaviridae family, which are not related to the Filoviridae family.
Choice D (Crimean-Congo virus and Hantaan virus) are part of the Nairoviridae and Hantaviridae families, respectively, and not the Filoviridae family.
Methods typically used to diagnose bacterial infections of the reproductive system include:
- A. microscopic examination of discharge from infected organ and microscopic examination of urine for organisms
- B. biopsy of infected tissue and use of selective media
- C. microscopic examination of fecal sample and protein test of urine
- D. antibody agglutination test and coagulation test
Correct Answer: A
Rationale: Step-by-step rationale for choice A being correct:
1. Microscopic examination of discharge from infected organ allows direct visualization of bacteria causing the infection.
2. Microscopic examination of urine for organisms can help identify any bacteria present in the urinary tract.
3. Both methods are specific for diagnosing bacterial infections in the reproductive system.
Summary:
- Choice B is incorrect as biopsy is invasive and not typically used for diagnosing bacterial infections.
- Choice C is incorrect as fecal samples and urine protein tests are not relevant for diagnosing bacterial infections in the reproductive system.
- Choice D is incorrect as antibody agglutination and coagulation tests are not primary methods for diagnosing bacterial infections in the reproductive system.
Examples for chemical vaccines are:
- A. Salk vaccine
- B. HPV vaccine
- C. Sabin vaccine
- D. Shiga anatoxin
Correct Answer: D
Rationale: The correct answer is D, Shiga anatoxin. This is because the Salk and Sabin vaccines are actually for polio, not chemical vaccines. HPV vaccine is a biological vaccine, not a chemical one. Shiga anatoxin is a chemical vaccine used against Shigella bacteria, making it the only correct choice for chemical vaccines in this question.
Resident microflora is found in
- A. blood
- B. lung
- C. urethra
- D. cerebro-spinal fluid
Correct Answer: C
Rationale: The correct answer is C: urethra. Resident microflora refers to the normal, beneficial bacteria that inhabit a specific area of the body without causing harm. The urethra is one of the locations where resident microflora are commonly found. These bacteria play a vital role in maintaining a healthy balance and preventing harmful pathogens from colonizing the urethra. Blood (A), lung (B), and cerebro-spinal fluid (D) are not typical locations for resident microflora as these areas are usually sterile or have very limited microbial presence to prevent infections.
Bacteriophages are:
- A. White blood cells that kill bacteria
- B. Bacteria that invade other bacteria
- C. Viruses that infect bacteria
- D. Bacteria that infect fungi
Correct Answer: C
Rationale: The correct answer is C: Bacteriophages are viruses that infect bacteria. Firstly, bacteriophages are viruses, not white blood cells or bacteria. They specifically target and infect bacteria, not fungi. This is known as a bacteriophage cycle where the virus injects its genetic material into the bacterial cell to replicate and eventually lyse the cell. This process is specific to bacteria and distinguishes bacteriophages from other microorganisms. Therefore, the correct answer is C as it accurately describes the nature and function of bacteriophages.