Which of the following sentences concerned with lymph node structure is incorrect?

Correct Answer: C

Rationale: Rationale: C is incorrect because naïve lymphocytes actually enter the lymph node through the afferent lymphatic vessel, not the efferent. A carries lymphocytes into the lymph node, and D is true since antigens enter through afferent vessels. B is correct, as naïve T cells are found in the paracortex.

Correct Answer: C

Rationale: The correct answer is C because innate immune response is not mediated by lymphocytes. Innate response involves physical barriers, such as skin and mucous membranes, and cells like macrophages and neutrophils. Lymphocytes are part of the adaptive immune response, which is characterized by specificity and memory. Choice A is correct as the innate response acts rapidly due to pre-existing mechanisms. Choice B is correct as adaptive response results in memory cells for quicker response upon re-exposure. Choice D is correct as adaptive response can recognize and respond to specific pathogens through antigen recognition.

Correct Answer: B

Rationale: The correct answer is B: Be highly immunogenic. A good vaccine should effectively stimulate the immune system to produce a strong immune response against the targeted pathogen while being safe for the individual. This is crucial for developing immunity without causing harm. Choice A (Be highly pathogenic) is incorrect because a vaccine should not cause disease or harm to the individual receiving it. Choice C (Induce herd immunity in a vaccinated individual) is also incorrect as herd immunity refers to protection of a population, not an individual. In summary, a good vaccine should be highly immunogenic to effectively trigger an immune response without causing harm, leading to protection against the targeted pathogen.

Correct Answer: B

Rationale: Explanation: An epitope is a specific region on an antigen that elicits the immune response and triggers the production of a specific antibody. Therefore, choice B is correct as it accurately defines an epitope. Choices A, C, and D are incorrect because they do not accurately describe what an epitope is. Choice A refers to the paratope, the region of the antibody that binds to the epitope. Choice C refers to a component of the antibody structure, and choice D refers to a specific region of the antibody structure.

Correct Answer: C

Rationale: Passive immunity is indicated when an individual needs immediate protection with ready-made antibodies after exposure to pathogens. This is the correct answer (C) as it provides immediate defense without waiting for the body to produce its antibodies. Choice A is incorrect because passive immunity is temporary, not permanent. Choice B is incorrect as it addresses treating allergic reactions, not providing immunity. Choice D is incorrect as a booster dose stimulates the body to produce its antibodies, not providing ready-made antibodies.