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openstax microbiology test bank Questions
Question 1 of 5
Viruses can infect
Correct Answer: D
Rationale: The correct answer is D because viruses have the ability to infect all organisms, including plants, bacteria, animals, and even fungi. Viruses are non-living entities that require a host cell to replicate and spread. They can infect a wide range of organisms by attaching to specific receptors on the host cell's surface. Therefore, the correct answer is D as viruses have the capability to infect all living organisms. Choices A, B, and C are incorrect because viruses can infect not only plants, bacteria, and animals but also other organisms, making choice D the most comprehensive and accurate option.
Question 2 of 5
A unique number that aids in finding additional toxicological information about a specific substance is the
Correct Answer: D
Rationale: The correct answer is D: RTECS number. The Registry of Toxic Effects of Chemical Substances (RTECS) number is a unique identifier assigned to chemicals and substances known to cause toxicological effects. It aids in accessing detailed toxicological information such as acute toxicity, carcinogenicity, and mutagenicity. The CAS number (A) is a unique numerical identifier for chemical compounds, not specifically for toxicological information. The atomic number (B) is the number of protons in an element's nucleus, unrelated to toxicology. The DOT ID number (C) is used for hazardous materials transportation, not for toxicological information. Therefore, the RTECS number is the correct choice for finding toxicological information about a specific substance.
Question 3 of 5
A smear prepared from material obtained from patient with suspected diphtheria contains yellow bacilli with blue grains at their ends. What staining was used in this case?
Correct Answer: D
Rationale: The correct answer is D: Loefler. This staining method is used for identifying Corynebacterium diphtheriae, the causative agent of diphtheria. It involves using methylene blue and basic fuchsin to stain the bacteria. The yellow bacilli with blue grains at their ends indicate the characteristic appearance of C. diphtheriae when stained using the Loefler method. Choice A: Ziehl-Nielsen is used for acid-fast bacteria like Mycobacterium tuberculosis. Choice B: Kozlovsky is not a standard staining method in microbiology. Choice C: Romanovsky is used for blood smears to identify malaria parasites.
Question 4 of 5
A patient suffers from pulmonary tuberculosis. During treatment neuritis of visual nerve arose. What drug has caused this by-effect?
Correct Answer: B
Rationale: The correct answer is B: Ethambutol. Ethambutol is known to cause optic neuritis, affecting the visual nerve. It is a well-documented side effect of this drug. Isoniazid (Choice A) is associated with peripheral neuropathy, not optic neuritis. Kanamycin (Choice C) is known for its side effects on the inner ear, causing hearing loss. Rifampicin (Choice D) is not typically associated with optic neuritis but can cause other adverse effects like hepatitis. By process of elimination and knowledge of drug side effects, Ethambutol is the most likely culprit.
Question 5 of 5
A 36-year-old man provisionally diagnosed with renal tuberculosis has undergone urinary sediment analysis. Microscopy revealed acid-fast bacteria, but Pryce method detected no cord factor. Name the most reliable method of investigation that can confirm or refute this provisional diagnosis:
Correct Answer: B
Rationale: The correct answer is B: Phage typing of the obtained culture. This method is used for typing Mycobacterium tuberculosis strains based on susceptibility to specific bacteriophages. If the culture shows susceptibility, it confirms the presence of M. tuberculosis. In this case, the absence of cord factor indicates that the bacteria are unlikely to be M. tuberculosis. Option A (Inoculation of laboratory animals) is unethical and not necessary when other methods are available. Option C (Allergy skin test) is not relevant for confirming a diagnosis of renal tuberculosis. Option D (Toxigenicity testing) is not specific for confirming or refuting a diagnosis of M. tuberculosis.