Nokea
For Parvovirus B19 is true that:
- A. Causes HBV
- B. Causes AIDS
- C. Causes erythema infectiosum
- D. Causes measles
Correct Answer: C
Rationale: The correct answer is C because Parvovirus B19 causes erythema infectiosum, also known as fifth disease. This virus primarily affects children and causes a distinctive red rash on the cheeks, arms, and legs. It is not associated with causing HBV (Hepatitis B Virus), AIDS, or measles. Parvovirus B19 specifically targets red blood cell precursors, leading to anemia in some cases. Understanding the characteristic clinical presentation and pathophysiology of the virus helps in selecting the correct answer.
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Which of the following viruses belong to family Arenaviridae?
- A. Lassa virus
- B. Crimean-Congo hemorrhagic fever virus
- C. Rabies virus
- D. Epstein-Barr virus
Correct Answer: A
Rationale: Step-by-step rationale:
1. Arenaviridae family includes viruses with a segmented genome.
2. Lassa virus has a segmented genome, placing it in the Arenaviridae family.
3. Crimean-Congo hemorrhagic fever virus belongs to the Nairoviridae family, not Arenaviridae.
4. Rabies virus belongs to the Rhabdoviridae family, not Arenaviridae.
5. Epstein-Barr virus belongs to the Herpesviridae family, not Arenaviridae.
Summary:
A: Lassa virus is correct because it has a segmented genome, characteristic of Arenaviridae.
B, C, D: Crimean-Congo hemorrhagic fever virus, Rabies virus, and Epstein-Barr virus belong to different virus families, not Arenaviridae.
Microscopic examination of a Gramstained scrape from patient's tongue revealed oval, round, elongated chains of dark-violet gemmating cells. What disease can be caused by this causative agent?
- A. Candidosis
- B. Actinomycosis
- C. Diphtheria
- D. Staphylococcic infection
Correct Answer: A
Rationale: Step 1: Oval, round, elongated chains of gemmating cells indicate yeast-like budding cells seen in Candida species.
Step 2: Candidosis is caused by Candida species, which is commonly found in the oral cavity and can cause infections on the tongue.
Step 3: Candidosis presents as white patches or plaques on the tongue.
Step 4: Therefore, the correct answer is A: Candidosis.
Summary:
B: Actinomycosis is caused by Actinomyces species, which are filamentous bacteria, not oval budding cells.
C: Diphtheria is caused by Corynebacterium diphtheriae, which appears as gram-positive rods in chains, not oval budding cells.
D: Staphylococcal infections are caused by Staphylococcus species, which appear as clusters of cocci, not oval budding cells.
The presence of flagella in bacterial cell represents:
- A. H-antigen
- B. O-antigen
- C. K-antigen
- D. None of the above
Correct Answer: A
Rationale: The presence of flagella in a bacterial cell represents the H-antigen. Flagella are protein structures on the cell surface that play a role in bacterial motility. The H-antigen refers to the flagellar antigen, which is involved in immune responses and bacterial identification. Option A is correct because flagella are specifically associated with the H-antigen.
Summarily, choices B and C are incorrect because the O-antigen and K-antigen are associated with lipopolysaccharide and capsule antigens, respectively, not flagella. Option D is incorrect as well because the correct association is with the H-antigen.
The primary stage of syphilis is usually manifested as:
- A. Diffuse maculopapular rush
- B. Purulent exudation from the urethra
- C. Syphilitic granulomas (gummas)
- D. Non-tender chancre (ulcus durum)
Correct Answer: D
Rationale: The correct answer is D: Non-tender chancre (ulcus durum). In the primary stage of syphilis, an individual typically develops a painless ulcer known as a chancre at the site of infection. This ulcer is usually firm, round, and clean with well-defined borders. It is important to note that it is non-tender, which distinguishes it from other skin conditions. This characteristic helps healthcare providers differentiate syphilis from other sexually transmitted infections.
Explanation for other choices:
A: Diffuse maculopapular rash - This is more commonly associated with secondary syphilis.
B: Purulent exudation from the urethra - This is not a typical presentation of primary syphilis.
C: Syphilitic granulomas (gummas) - Gummas typically develop in the tertiary stage of syphilis, not in the primary stage.
Growth factors are substances which:
- A. Cannot be synthesized in the bacterial cells but are important for their growth
- B. Bacterial cells can synthesize in limited amount
- C. Bacterial cells store in the form of granules
- D. Bacterial cells synthesis in a large amount
Correct Answer: A
Rationale: The correct answer is A because growth factors are essential nutrients that bacteria cannot synthesize on their own and must obtain from the environment for their growth. Bacteria rely on these external factors for processes like cell division, metabolism, and survival. Choice B is incorrect because bacteria can only synthesize growth factors in limited amounts, not sufficient for their growth. Choice C is incorrect as bacterial cells do not store growth factors in granules. Choice D is incorrect because bacterial cells do not synthesize growth factors in large amounts.