Which of the following is not a method used by bacteria to acquire genetic material?

Correct Answer: D

Rationale: The correct answer is D: Binary fission. Binary fission is a method of bacterial cell division, not a method of acquiring genetic material. Transformation, conjugation, and transduction are mechanisms through which bacteria can acquire genetic material from other sources. Transformation involves the uptake of naked DNA from the environment, conjugation is the transfer of genetic material through direct cell-to-cell contact, and transduction is the transfer of genetic material via bacteriophages. Therefore, binary fission is the only option that does not involve the acquisition of new genetic material.

Correct Answer: C

Rationale: The correct answer is C: Leishmaniasis. The description of thin microorganisms with 12-14 uniform tendrils, 10-13 micrometers in length, and pale pink color matches the characteristics of Leishmania parasites seen in Giemsa-stained samples. Leishmania parasites are known to have a distinctive appearance with pointed tips and a specific size range. Syphilis (choice A) is caused by Treponema pallidum, which appears as tightly coiled spirochetes, not tendrils. Trypanosomiasis (choice B) is caused by Trypanosoma parasites, which have a different morphology and staining pattern. Relapsing fever (choice D) is caused by Borrelia recurrentis, which does not match the description given. Therefore, the correct choice is C as the description aligns closely with the characteristic features of Leishmania parasites.

Correct Answer: A

Rationale: The correct answer is A: Entamoeba gingivalis. This organism matches the description provided in the question - unicellular with pseudopodia and ingested white blood cells, commonly found in dental plaque. Entamoeba gingivalis is known to inhabit the oral cavity and is associated with periodontal disease. Trichomonas vaginalis, Giardia lamblia, and Balantidium coli do not match the characteristics mentioned in the question and are not typically found in the oral cavity.

Correct Answer: A

Rationale: The correct answer is A: T-lymphocytes. Cell-mediated immunity involves the activation of T-lymphocytes, which play a crucial role in recognizing and killing infected cells. T-lymphocytes include cytotoxic T cells, helper T cells, and regulatory T cells, all of which are involved in different aspects of cell-mediated immunity. Monocytes (choice B) are a type of white blood cell involved in phagocytosis but are not the main mediators of cell-mediated immunity. B-lymphocytes (choice C) are involved in humoral immunity, producing antibodies, not cell-mediated immunity. Choice D (A+B+C) is incorrect because cell-mediated immunity is mainly mediated by T-lymphocytes.

Correct Answer: A

Rationale: Passive immunity is the transfer of pre-formed antibodies from one individual to another, providing immediate protection. This process does not involve the recipient's immune response, hence it is called passive. Active immunity, on the other hand, involves the individual's immune system producing its own antibodies after exposure to an antigen. Innate immunity refers to the body's natural defense mechanisms present from birth, not involving antibodies. Therefore, the correct answer is A: passive immunity.

Correct Answer: D

Rationale: The correct answer is D: BSL4. Ebola viruses are highly infectious and pose a high risk to laboratory workers. BSL4 facilities are designed to handle agents that pose a severe threat to human health and have no available vaccines or treatments. These facilities have strict guidelines for handling infectious agents, including full-body suits, negative air pressure, and decontamination processes to prevent any possible exposure. BSL1, BSL2, and BSL3 are not adequate for handling Ebola viruses due to their lower levels of containment and safety measures.

Correct Answer: B

Rationale: The correct answer is B: Clostridium tetani. Clostridium tetani produces tetanospasmin, a neurotoxin causing tetanus. It enters the body through wounds and affects the nervous system. A: Clostridium botulinum produces botulinum toxin causing botulism, not tetanus. C: Streptococcus pneumoniae causes pneumonia, not tetanus. D: Mycobacterium tuberculosis causes tuberculosis, not tetanus.

Correct Answer: A

Rationale: Step-by-step rationale for choice A: 1. Viruses contain genetic material in the form of nucleic acids (DNA or RNA). 2. Proteins are essential for the structure and function of viral particles. 3. Nucleic acids (genetic material) and proteins are the two main components of viruses. 4. Therefore, choice A (nucleic acid and proteins) is correct. Summary: - Choice B (nucleic acids and lipids) is incorrect as lipids are not a main structural component of viruses. - Choice C (lipids and proteins) is incorrect as nucleic acids are essential components of viruses. - Choice D (proteins and glycoproteins) is incorrect as glycoproteins are a type of protein and not a separate component in viruses.

Correct Answer: D

Rationale: The correct answer is D (15-Oct) because boiling items for at least 15 minutes is necessary to effectively kill most vegetative bacteria and viruses. This duration ensures that the water reaches a high enough temperature to destroy harmful microorganisms. Choices A, B, and C are incorrect because they do not provide a sufficient amount of time for the water to reach the necessary temperature to effectively kill bacteria and viruses. Shorter durations may not be effective in ensuring food safety.