Nokea
For family Togaviridae is true that
- A. they have helical type of symmetry
- B. they have non-segmented (-)dsRNA
- C. they have non-segmented (+)ssRNA
- D. they are non-enveloped viruses
Correct Answer: C
Rationale: Step 1: Togaviridae is a family of viruses known to have non-segmented (+)ssRNA as their genetic material.
Step 2: The positive sense RNA means that the viral RNA can be directly translated into proteins by host machinery.
Step 3: This RNA genome acts as mRNA, allowing for immediate translation of viral proteins.
Step 4: Therefore, choice C is correct as it accurately describes the genetic nature of Togaviridae.
Summary:
- Choice A is incorrect because Togaviridae viruses do not have helical symmetry.
- Choice B is incorrect because Togaviridae viruses do not have non-segmented (-)dsRNA.
- Choice D is incorrect because Togaviridae viruses are enveloped viruses.
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A patient was taken to a hospital with acute food poisoning caused by homemade canned mushrooms. The product analysis revealed some microorganisms that develop only in the absence of oxygen. What microorganisms caused the poisoning?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Microaerophiles
- D. Obligate aerobes
Correct Answer: A
Rationale: The correct answer is A: Obligate anaerobes. These microorganisms thrive in the absence of oxygen, as seen in the canned mushrooms where oxygen is limited. They produce toxins causing food poisoning. Facultative anaerobes (B) can survive with or without oxygen. Microaerophiles (C) require low levels of oxygen. Obligate aerobes (D) need oxygen to survive and would not be responsible for the poisoning in this case.
After the transfer of the F plasmid from the donor to the recipient cell..
- A. It is not possible to predict the outcome
- B. The donor cells become F
- C. The two cells become F
- D. The two cells become F+
Correct Answer: D
Rationale: After the transfer of the F plasmid from the donor to the recipient cell, the correct answer is D. This is because the F plasmid carries genes for conjugation, allowing the recipient cell to become F+ (containing the F plasmid). The donor cell remains F. Choice A is incorrect as the outcome can be predicted based on the transfer of the F plasmid. Choice B is incorrect because the donor cell does not become F after transferring the F plasmid. Choice C is incorrect as only the recipient cell becomes F+, not both cells.
What type of bacteria is responsible for the formation of acid in the stomach?
- A. Staphylococcus aureus
- B. Helicobacter pylori
- C. Bacillus cereus
- D. Clostridium botulinum
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is responsible for stomach acid formation by producing an enzyme called urease, which converts urea into ammonia and carbon dioxide, leading to an increase in stomach pH. Staphylococcus aureus (A) does not cause stomach acid formation. Bacillus cereus (C) and Clostridium botulinum (D) are not involved in stomach acid processes.
A 32 year old patient complains about heartburn and dull pain in the epigastrium that appear 2-3 hours after meal. Exacerbations happen in spring and in autumn. The patient has food intolerance of eggs and fish. Objectively: stomach palpation reveals painfulness in the gastroduodenal area. Electrophasoduodenoscopy revealed a 5 mm ulcer on the anterior wall of duodenum. Urease test is positive. What is the most probable leading mechanism of disease development?
- A. Helicobacterial infection
- B. Dietary allergy
- C. Autoantibody production
- D. Reduced prostaglandin synthesis
Correct Answer: A
Rationale: The correct answer is A: Helicobacterial infection. This is the most probable leading mechanism of disease development in this case because the patient's symptoms, such as heartburn, epigastric pain, food intolerance, and presence of a duodenal ulcer with a positive urease test, are classic signs of Helicobacter pylori infection. This bacterium colonizes the stomach lining, leading to inflammation and ulcer formation. The exacerbations in spring and autumn could be due to seasonal variations in immune response.
Choice B: Dietary allergy is incorrect because the symptoms and findings in the patient are more indicative of an infectious etiology rather than an allergic reaction to specific foods.
Choice C: Autoantibody production is unlikely as there are no indications of an autoimmune process in this case.
Choice D: Reduced prostaglandin synthesis is not the leading mechanism as the symptoms and findings are more consistent with an infectious cause rather than a deficiency in prostaglandin synthesis.
There are several cases of children from boarding school suffering from sore throat. Microscopy of tonsil smears stained according Neisser method has revealed thin yellow bacilli with dark brown grains on their ends placed in the shape of Roman numeral five. What infection can be suspected in this case?
- A. Diphtheria
- B. Scarlet fever
- C. Listeriosis
- D. Tonsilitis
Correct Answer: A
Rationale: Rationale for Correct Answer A (Diphtheria):
1. Thin yellow bacilli with dark brown grains on ends suggest Corynebacterium diphtheriae, characteristic of diphtheria.
2. Roman numeral five shape is typical of diphtheria bacilli.
3. Diphtheria causes sore throat and can spread in boarding schools.
4. Neisser staining method is used for diphtheria bacilli.
Summary of Incorrect Choices:
B: Scarlet fever is caused by Streptococcus pyogenes and presents with rash, not yellow bacilli.
C: Listeriosis is caused by Listeria monocytogenes, not consistent with the described findings.
D: Tonsillitis can be caused by various bacteria or viruses, but the specific characteristics described do not match.