Nokea
The binominal system of nomenclature was originally developed by
- A. Pasteur
- B. Linnaeus
- C. Martini
- D. Jenner
Correct Answer: B
Rationale: The correct answer is B: Linnaeus. Linnaeus developed the binomial system of nomenclature in the 18th century. This system uses a two-part naming system consisting of the genus and species name to classify and identify organisms. Linnaeus's contribution revolutionized the way organisms are named and classified in the field of biology. Other choices are incorrect as Pasteur is known for his work in microbiology, Martini is not associated with the development of binomial nomenclature, and Jenner is known for developing the smallpox vaccine.
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A 22-year-old patient is a clerk. His working day runs in a conditioned room. In summer he was taken by an acute disease with the following symptoms: fever, dyspnea, dry cough, pleural pain, myalgia, arthralgia. Objectively: moist rales on the right, pleural friction rub. X-ray picture showed infiltration of the inferior lobe. In blood: WBC - 11 · 109/l, stab neutrophils - 6%, segmented neutrophils - 70%, lymphocytes - 8%, ESR - 42 mm/h. What is the etiological factor pneumonia?
- A. Legionella
- B. Mycoplasma
- C. Streptococcus
- D. Staphylococcus
Correct Answer: C
Rationale: The correct answer is C: Streptococcus. Streptococcus pneumoniae is the most common etiological factor for community-acquired pneumonia in young adults. The symptoms described align with typical pneumococcal pneumonia presentation. Presence of pleural friction rub and infiltration in the X-ray support the diagnosis. The blood work showing elevated WBC count with a left shift (increased neutrophils and low lymphocytes) and elevated ESR is consistent with a bacterial infection. Legionella and Mycoplasma typically present with atypical pneumonia symptoms such as headache, confusion, and GI symptoms, which are not described in the case. Staphylococcus pneumonia is not a common cause of community-acquired pneumonia in young adults.
Which of the following statements for S. Aureus is FALSE
- A. it is always susceptible for penicillin
- B. around its colonies there is a beta hemolytic zone
- C. it produces hemolysins, leucocidins, enterotoxins
- D. has a positive catalase reaction
Correct Answer: A
Rationale: The correct answer is A because Staphylococcus aureus can develop resistance to penicillin over time due to the production of beta-lactamase enzymes. This resistance mechanism makes it no longer susceptible to penicillin. The other choices are correct: B) S. aureus can produce beta hemolysis, C) it produces various toxins like hemolysins, leucocidins, and enterotoxins, and D) it shows a positive catalase reaction due to the presence of catalase enzyme that converts hydrogen peroxide to water and oxygen.
Virulence
- A. Is the degree of pathogenicity
- B. Of the microorganism is not a constant characteristic
- C. Can be measured with LD50
- D. All the answers are true
Correct Answer: D
Rationale: The correct answer is D because virulence refers to the degree of pathogenicity of a microorganism, which can vary and is not a constant characteristic. It can be measured using LD50, which is the lethal dose that kills 50% of the test population. Therefore, all the statements in options A, B, and C are true and collectively provide a comprehensive understanding of virulence.
Which of the following diseases is generally caused by contaminated food?
- A. Mumps
- B. Shigellosis
- C. Legionellosis
- D. Tuberculosis
Correct Answer: B
Rationale: The correct answer is B: Shigellosis. Shigellosis is caused by the bacteria Shigella, commonly transmitted through contaminated food and water. The bacteria can spread easily in unsanitary conditions. Mumps (A) is a viral infection spread through respiratory droplets. Legionellosis (C) is caused by the Legionella bacteria found in water sources like cooling towers. Tuberculosis (D) is a bacterial infection transmitted through the air. Therefore, the correct answer is B as it directly relates to contaminated food transmission.
Nonchromosomal DNA molecules found in a bacterial cell are
- A. endospores.
- B. transposons.
- C. plasmids.
- D. prions.
Correct Answer: C
Rationale: The correct answer is C: plasmids. Plasmids are nonchromosomal DNA molecules commonly found in bacterial cells, providing additional genetic material for bacteria. They are not essential for bacterial survival but can confer advantages such as antibiotic resistance. Endospores (A) are dormant bacterial structures resistant to harsh conditions. Transposons (B) are mobile genetic elements that can move within a genome. Prions (D) are misfolded proteins causing neurodegenerative diseases, not DNA molecules.