Nokea
The prokaryotic cell does not possess:
- A. Ribosomes
- B. Endoplasmic reticulum
- C. Chromosome
- D. Peptidoglycan
Correct Answer: B
Rationale: The correct answer is B: Endoplasmic reticulum. Prokaryotic cells lack membrane-bound organelles like the endoplasmic reticulum, which is present in eukaryotic cells. Prokaryotes do possess ribosomes for protein synthesis (A), a chromosome (C) for genetic material, and peptidoglycan (D) in their cell walls. The absence of endoplasmic reticulum is a key characteristic that distinguishes prokaryotic cells from eukaryotic cells.
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The catarrhal stage of the whooping cough is characterized by:
- A. Decrease in paroxysms of coughing
- B. Subsequent respiratory infection for many months after the onset of pertussis
- C. Uncontrollable coughing followed by a high pitched 'whoop' sound
- D. Mild respiratory symptoms (mild coughing, sneezing or a runny nose)
Correct Answer: D
Rationale: The correct answer is D because the catarrhal stage of whooping cough is characterized by mild respiratory symptoms such as mild coughing, sneezing, or a runny nose. During this stage, the cough may start to worsen but is not yet severe.
A: Incorrect - Decrease in paroxysms of coughing is not seen in the catarrhal stage; it occurs later in the paroxysmal stage.
B: Incorrect - Subsequent respiratory infection for many months after the onset of pertussis is not a characteristic of the catarrhal stage.
C: Incorrect - Uncontrollable coughing followed by a high pitched 'whoop' sound is typical of the paroxysmal stage, not the catarrhal stage.
Bacteriology testing is one of the methods for laboratory diagnostics of diphtheria. To grow the
- A. diphtheriae, it is necessary to know the proper conditions for causative agent cultivation. What nutrient media are optimal for Corynebacterium diphtheriae cultivation?
- B. Sugar meat pepton broth, sugar meat pepton agar
- C. Salt egg yolk agar
- D. Endomedium, Ploskirev medium
Correct Answer: B
Rationale: The correct answer is B: Sugar meat pepton broth, sugar meat pepton agar. These nutrient media are optimal for Corynebacterium diphtheriae cultivation due to their ability to support the growth of this bacterium. Sugar meat pepton broth provides a liquid medium with essential nutrients, while sugar meat pepton agar provides a solid surface for bacterial growth and isolation.
Incorrect choices:
A: Diphtheriae does not require specific conditions for cultivation.
C: Salt egg yolk agar is not commonly used for Corynebacterium diphtheriae.
D: Endomedium and Ploskirev medium are not standard media for diphtheria testing.
After a prolonged isoniazid treatment, the patient developed polyneuritis, paresthesia, memory disorders, and convulsions. What is the most likely mechanism of the described isoniazid side-effects?
- A. Disruption of cell membrane synthesis
- B. Inhibition of protein synthesis
- C. Inhibition of RNA-synthesis
- D. Inhibition of pyridoxal phosphate synthesis
Correct Answer: D
Rationale: The correct answer is D. Isoniazid inhibits pyridoxal phosphate synthesis, which is the active form of vitamin B6. Pyridoxal phosphate is essential for various enzymatic reactions, including neurotransmitter synthesis and myelin formation. Therefore, isoniazid-induced pyridoxal phosphate deficiency can lead to neurological symptoms like polyneuritis, paresthesia, memory disorders, and convulsions.
A: Disruption of cell membrane synthesis - This is not the mechanism of isoniazid side-effects.
B: Inhibition of protein synthesis - Isoniazid does not directly inhibit protein synthesis.
C: Inhibition of RNA-synthesis - Isoniazid does not inhibit RNA synthesis; it affects vitamin B6 metabolism.
Which structure is used by bacteria for movement?
- A. Pili
- B. Flagella
- C. Capsule
- D. Fimbriae
Correct Answer: B
Rationale: The correct answer is B: Flagella. Flagella are whip-like appendages used by bacteria for movement. They rotate in a corkscrew motion to propel the bacteria through their environment. Pili (choice A) are hair-like structures used for attachment, not movement. Capsules (choice C) are protective layers around bacteria, not involved in movement. Fimbriae (choice D) are also used for attachment and biofilm formation, not for movement. Therefore, the correct choice is B as flagella are specifically adapted for bacterial motility.
A 14-year-old patient was diagnosed with Hutchinson's triad: barrel-shaped incisors, parenchymatous keratitis and deafness. The revealed presentations are consistent with the following disease:
- A. Syphilis
- B. Toxoplasmosis
- C. Lepra
- D. Tuberculosis
Correct Answer: A
Rationale: The correct answer is A: Syphilis. Hutchinson's triad is a classic presentation of congenital syphilis in children. Barrel-shaped incisors, parenchymatous keratitis, and deafness are key manifestations. Barrel-shaped incisors result from mulberry molars, a type of abnormal tooth. Parenchymatous keratitis is an inflammation of the cornea, a common ocular sign in congenital syphilis. Deafness can occur due to damage to the auditory nerve caused by the infection. Choices B, C, and D are incorrect as they do not typically present with the specific triad of symptoms seen in congenital syphilis.