Agents associated with human disease but generally not a serious health risk are classified in which of the following risk groups?
- A. RG1
- B. RG2
- C. RG3
- D. RG4
Correct Answer: B
Rationale: The correct answer is B: RG2. RG2 is appropriate for agents associated with human disease that pose a moderate health risk. These agents may cause disease of varying severity, but generally do not result in serious health consequences. Other choices are incorrect because: A: RG1 is for agents not associated with disease in healthy adults, C: RG3 is for agents associated with serious or lethal human disease, and D: RG4 is for agents that pose a high risk of life-threatening disease and for which there are no treatments.
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Nigrosin is a stain used in:
- A. simple staining
- B. gram staining
- C. negative staining
- D. acid-fast staining
Correct Answer: C
Rationale: Nigrosin is used in negative staining, where the background is stained instead of the cells themselves. This technique helps highlight the morphology and structure of cells that may be damaged by traditional staining methods. Nigrosin is negatively charged and repels the negatively charged bacterial cells, resulting in a clear halo around the cells. This process is particularly useful for observing capsules and determining cell size and shape. The other options are incorrect because simple staining uses a single dye to color the entire cell, gram staining involves a series of dyes to differentiate between gram-positive and gram-negative bacteria, and acid-fast staining is used to detect acid-fast organisms like Mycobacterium.
Microscopic examination of a microbial culture revealed fusiform spore-forming microorganisms that get violet-blue Gram's stain. What microorganisms were revealed?
- A. Clostridia
- B. Streptococci
- C. Spirochaete
- D. Actinomycete
Correct Answer: A
Rationale: The correct answer is A: Clostridia. Fusiform spore-forming microorganisms that stain violet-blue with Gram's stain are characteristic of Clostridia. Clostridia are anaerobic, rod-shaped bacteria known for their ability to form spores and cause diseases such as tetanus and botulism.
Summary of other choices:
B: Streptococci are spherical, not fusiform, and typically do not form spores.
C: Spirochaete are spiral-shaped bacteria and do not typically form spores.
D: Actinomycete are filamentous bacteria that do not typically form spores and do not stain violet-blue with Gram's stain.
Aflatoxins are produced by:
- A. Genus Cryptococcus
- B. Genus Actinomyces
- C. Genus Streptococcus
- D. Genus Aspergillus
Correct Answer: D
Rationale: The correct answer is D: Genus Aspergillus. Aflatoxins are toxic compounds produced by certain species of fungi, particularly Aspergillus species. Aspergillus flavus and Aspergillus parasiticus are well-known producers of aflatoxins. These fungi can contaminate crops such as peanuts, corn, and tree nuts, leading to potential health risks. Cryptococcus (A), Actinomyces (B), and Streptococcus (C) are not known to produce aflatoxins. It is important to be aware of the sources and implications of aflatoxin contamination to ensure food safety and public health.
The discipline addressing issues associated with the choice and application of drugs to be used for disease prevention, treatment, and/or diagnosis is:
- A. pharmacotherapeutics
- B. toxicology
- C. pharmacokinetics
- D. pharmacy
Correct Answer: A
Rationale: The correct answer is A: pharmacotherapeutics. Pharmacotherapeutics focuses on the selection and use of drugs for disease prevention, treatment, and diagnosis. It involves determining the most effective and safe medications for specific conditions based on patient factors. Toxicology (B) is the study of the adverse effects of chemicals, including drugs. Pharmacokinetics (C) focuses on drug absorption, distribution, metabolism, and excretion in the body. Pharmacy (D) involves the preparation and dispensing of medications, but does not specifically address drug selection and application for disease management. Therefore, pharmacotherapeutics is the most suitable discipline for addressing the use of drugs in disease management.
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.