Which of the following is not a function of the immune system?

Correct Answer: B

Rationale: The correct answer is B: Producing hormones. The immune system's main functions are to protect the body from foreign substances and repair damaged tissues. Producing hormones is not a direct function of the immune system. Hormone production is primarily regulated by the endocrine system, not the immune system. Therefore, option B is not a function of the immune system. Options A and C are incorrect as protecting the body from foreign substances and repairing damaged tissues are essential roles of the immune system. Option D is incorrect because not all functions listed are actually performed by the immune system.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Lysozyme is an enzyme that destroys bacterial cell walls. 2. This action acts as a preformed chemical barrier against pathogens. 3. Mucus (choice A) is a physical barrier, not a preformed chemical one. 4. Tight junctions (choice C) and cilia (choice D) are structural components, not chemical barriers. Summary: - Choice B, Lysozyme, is correct as it actively targets and destroys pathogens. - Choices A, C, and D are incorrect as they do not directly function as preformed chemical barriers.

Correct Answer: C

Rationale: The correct answer is C: Mast cells: acute phase response. Mast cells are actually involved in allergic responses, not the acute phase response of the immune system. The acute phase response is primarily mediated by cytokines and acute-phase proteins. Interferons protect against viral infections, ROS help kill pathogens inside cells, and selectins aid in leukocyte extravasation during inflammation.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Immunoglobulins are antibodies produced by the immune system to recognize and bind to foreign molecules called antigens. These antigens can be proteins (choice A), carbohydrates (choice B), or lipids (choice C). Therefore, immunoglobulins can bind to all classes of biological molecules. Choices A, B, and C are incorrect as they each represent individual classes of molecules that can be targeted by immunoglobulins, but the correct answer encompasses all of them.

Correct Answer: D

Rationale: Rationale: 1. A is correct as lymph is taken up from tissues by lymphatic capillaries. 2. B is correct as lymph carries antigens and mature dendritic cells to lymph nodes. 3. C is incorrect as lymph is not secreted by lymphocytes. 4. Therefore, D is correct as both A and B accurately describe the components and functions of lymph.