ATI RN
mastering microbiology test bank Questions
Question 1 of 5
Chlorine belongs to which of the following chemical groups?
Correct Answer: A
Rationale: The correct answer is A: Halogens. Chlorine belongs to the halogens group because it is a nonmetal element in group 17 of the periodic table. Halogens are highly reactive elements that have 7 electrons in their outer shell, making them eager to gain an electron to achieve stability. Chlorine specifically is a diatomic molecule with the chemical symbol Cl and atomic number 17. Option B: Heavy metals are elements with high atomic weights and densities, such as lead and mercury, which are not related to chlorine. Option C: Phenols are a class of organic compounds containing a hydroxyl group bonded to an aromatic ring, not related to chlorine. Option D: Alcohols are organic compounds characterized by the presence of a hydroxyl group (-OH), also not related to chlorine.
Question 2 of 5
A bacteriological laboratory received sputum sample of a patient suffering from tuberculosis. Bacterioscopic examination of smears and detection of tuberculosis bacillus can be realized by one of enrichment methods that involves processing of sputum only with solution of caustic soda. What is this method called?
Correct Answer: B
Rationale: The correct answer is B: Inactivation. In this method, the sputum sample is processed with a solution of caustic soda, which helps to kill any contaminants present and preserve the tuberculosis bacillus for microscopic examination. This step is crucial in ensuring accurate detection of the bacillus. A: Homogenization involves breaking down the sample to make it uniform, but it does not necessarily involve using caustic soda for inactivation. C: Flotation is a method used to separate different components based on their density and is not specific to inactivating tuberculosis bacillus. D: Filtration involves passing a sample through a filter to separate particles based on size and is not related to inactivating the tuberculosis bacillus.
Question 3 of 5
Tuberculosis can be treated by means of combined chemotherapy that includes substances with different mechanisms of action. What antituberculous medication inhibits transcription of RNA into DNA in mycobacteria?
Correct Answer: A
Rationale: Rifampicin is the correct answer because it inhibits RNA transcription in mycobacteria by binding to the bacterial RNA polymerase. This prevents the synthesis of RNA, leading to the inhibition of protein production essential for bacterial growth. Isoniazid inhibits mycolic acid synthesis, Streptomycin inhibits protein synthesis, and Ethionamide disrupts mycolic acid synthesis. These mechanisms are different from inhibiting RNA transcription, making them incorrect choices.
Question 4 of 5
A centrifugate of urine sample obtained from patient with suspected renal tuberculosis was used to make a slide mount for microscopy. What method should be used to stain the slide and detect the causative agent?
Correct Answer: A
Rationale: The correct answer is A: Zielh-Neelsen stain. This stain is specifically used to detect acid-fast bacteria like Mycobacterium tuberculosis, the causative agent of renal tuberculosis. The staining process involves using carbol fuchsin to penetrate the mycolic acid layer of the bacterial cell wall, making it resistant to decolorization with acid-alcohol. This allows the red stained bacteria to be visualized under a microscope. Loeffler stain (B) is used for staining bacteria like diphtheria bacilli, Gram stain (C) is used for bacterial classification based on cell wall properties, and Aujeszky stain (D) is not a recognized staining method for detecting acid-fast bacteria.
Question 5 of 5
A 34 year old male patient consulted a doctor about face carbuncle. Objectively: a loose, painless edema of hypodermic tissue; black crust in the center of carbuncle, vesicular rash around it. Microbiological examination revealed static streptobacilli capable of capsule building. What microorganisms are the causative agents of this disease?
Correct Answer: B
Rationale: The correct answer is B: Staphylococcus aureus. This bacterium is a common causative agent of skin infections like carbuncles. Staphylococcus aureus is known for its ability to produce pus-filled abscesses, which aligns with the symptoms described in the question. The presence of a vesicular rash around the carbuncle further supports this diagnosis, as Staphylococcus aureus can cause skin lesions. The other choices are not correct because: A: Bacillus anthracis causes anthrax, which presents with different symptoms such as fever, malaise, and respiratory symptoms. C: Bacillus subtilis is a harmless soil bacterium commonly used in research and not known to cause skin infections. D: Bacillus anthracoides is not a known pathogen and is not associated with human infections.