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A patient with abdominal pain and diarrhea had a stool culture revealing non-lactose-fermenting, Gram-negative rods. What is the most likely causative agent?
- A. Shigella dysenteriae
- B. Salmonella typhi
- C. Escherichia coli
- D. Proteus vulgaris
Correct Answer: A
Rationale: The correct answer is A: Shigella dysenteriae. Shigella causes dysentery, characterized by bloody diarrhea and abdominal pain. Shigella is a non-lactose-fermenting, Gram-negative rod.
B: Salmonella typhi causes typhoid fever, not typically associated with abdominal pain and diarrhea.
C: Escherichia coli, a common gut bacteria, can cause diarrhea but typically ferments lactose.
D: Proteus vulgaris is not a common cause of gastrointestinal infection and is not typically associated with abdominal pain and diarrhea.
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Which of the following viruses belong to family Arenaviridae
- A. Lassa virus
- B. Crimean-Congo hemorrhagic fever virus
- C. Rabies virus
- D. Epstein-Bar virus
Correct Answer: A
Rationale: The correct answer is A: Lassa virus. The rationale is as follows:
1. Lassa virus is a member of the Arenaviridae family, known for causing Lassa fever.
2. Arenaviridae family includes viruses with a segmented genome and are transmitted through rodents.
3. Crimean-Congo hemorrhagic fever virus (Choice B) belongs to the Bunyaviridae family, not Arenaviridae.
4. Rabies virus (Choice C) belongs to the Rhabdoviridae family, not Arenaviridae.
5. Epstein-Barr virus (Choice D) belongs to the Herpesviridae family, not Arenaviridae.
In summary, Lassa virus is the correct choice as it aligns with the characteristics of the Arenaviridae family, while the other choices belong to different virus families.
Which of the following statements for genus Klebsiella is correct?
- A. They have real capsule and are non-motile
- B. They are obligatory anaerobic
- C. They form spores only under aerobic conditions
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A because Klebsiella species have a real capsule, which is a distinguishing feature used for their identification. This capsule helps them evade the host immune response. Additionally, Klebsiella species are non-motile, meaning they do not possess flagella for movement. Choices B and C are incorrect because Klebsiella species are facultative anaerobes and do not form spores under any conditions. Choice D is also incorrect as option A is the correct statement for genus Klebsiella.
Enzymatic reactions can be expressed in which of the following chemical notations?
- A. S + P = E
- B. P + P = E
- C. E + S = P
- D. S + S = P
Correct Answer: C
Rationale: The correct answer is C: E + S = P. This notation represents the interaction between an enzyme (E) and a substrate (S) resulting in a product (P). Enzymes facilitate chemical reactions by binding to substrates and converting them into products. Choice A is incorrect because it does not include the enzyme in the reaction. Choice B is incorrect as it involves two substrates binding to the enzyme, not a substrate converting to a product. Choice D is incorrect as it shows two substrates reacting to form a product without involvement of an enzyme. Thus, choice C accurately represents the process of enzymatic reactions involving enzymes, substrates, and products.
In which of the following cases of immune reactions a large lattice is formed?
- A. Antibody is in excess
- B. Antigens and antibodies are in optimal proportion
- C. Antigen is in excess
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B because in immune reactions, a large lattice is formed when antigens and antibodies are in optimal proportion. This optimal ratio allows for the formation of a strong antigen-antibody complex, leading to the aggregation of immune complexes into large lattice structures. When antibodies are in excess (choice A), there may not be enough antigens to form a stable lattice. Similarly, when antigens are in excess (choice C), there may be insufficient antibodies to form a strong lattice. Choice D is incorrect because the optimal proportion of antigens and antibodies is crucial for the formation of large lattices in immune reactions.
The cleanup of various industrial wastes by living organisms is referred to as __________.
- A. biomining
- B. biosynthesis
- C. bioremediation
- D. bioengineering
Correct Answer: C
Rationale: The correct answer is C: bioremediation. Bioremediation is the process of using living organisms to clean up environmental pollution, including industrial wastes. This method utilizes microorganisms, plants, or fungi to break down or neutralize pollutants. Biomining (A) is the process of extracting valuable metals from ores using biological organisms. Biosynthesis (B) refers to the production of complex molecules by living organisms. Bioengineering (D) involves the application of engineering principles to biological systems, not specifically related to cleaning up industrial wastes. Therefore, the most appropriate term for the cleanup of industrial wastes by living organisms is bioremediation.