A dimorphic fungus growing as a mold prefers what temperature?

Correct Answer: C

Rationale: The correct answer is C (25°C) because dimorphic fungi typically grow as molds at lower temperatures. At 25°C, the fungus is likely in its mold phase, which is the preferred temperature range for mold growth. Choices A, B, and D are incorrect because 15°C and 20°C are too low for optimal mold growth, and 37°C is too high as it typically favors the yeast phase of dimorphic fungi. Therefore, the preferred temperature for mold growth of a dimorphic fungus is 25°C.

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.

Correct Answer: C

Rationale: The correct answer is C: rotaviruses. Rotaviruses are the most common cause of infectious diarrhea in infants and children due to their highly contagious nature and ability to spread easily in childcare settings. They are known to cause severe diarrhea, vomiting, and dehydration in young children. Noroviruses (A), adenoviruses (B), and caliciviruses (D) can also cause diarrhea, but rotaviruses are specifically known for their prevalence and severity in the pediatric population. This is why C is the correct answer.

Correct Answer: A

Rationale: The correct answer is A, Clostridium botulinum. This bacterium produces botulinum toxin, leading to botulism. It is commonly found in soil and improperly canned food. Clostridium tetani causes tetanus, Staphylococcus aureus causes food poisoning, and Salmonella enterica causes salmonellosis. Therefore, A is correct due to its association with botulism, while the other choices are incorrect for causing different diseases.

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: A

Rationale: The correct answer is A: TRUE. The structures and organs listed are indeed part of the immune system. The lymphatic system transports lymph, lymphoid tissue contains immune cells, lymph nodes filter lymph, thymus matures T-cells, and spleen filters blood and produces immune cells. This comprehensive network is crucial for defending the body against pathogens. Choice B is incorrect as all listed structures are components of the immune system. Choice C is also incorrect as the statement is universally true, not situational. Choice D is incorrect as the correct answer is A.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Sodium is the major cation in the intracellular fluid. 2. It plays a crucial role in maintaining cell volume and transmitting nerve impulses. 3. Potassium is the major cation in the extracellular fluid, not intracellular. 4. Bicarbonate and sulfate are anions and not major cations in intracellular fluid. Summary: Choice B (sodium) is correct as it is the major cation in intracellular fluid, essential for various cellular functions. Choices A, C, and D are incorrect as potassium is extracellular, while bicarbonate and sulfate are anions and not predominant cations in intracellular fluid.

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: B

Rationale: The main function of bacterial pili is to facilitate conjugation and adhesion. Pili are hair-like appendages on bacteria that help in cell-to-cell interactions. They play a crucial role in bacterial conjugation by allowing the transfer of genetic material between cells. Additionally, pili help bacteria adhere to surfaces or host cells, aiding in colonization and biofilm formation. Choices A and D are incorrect because protein synthesis and toxin secretion are not the primary functions of pili. Choice C is incorrect as bacterial motility is mainly mediated by flagella, not pili.