Name 3 signs you might see on examination of a patient’s face, skin, and nails that are associated with iron deficiency anaemia. (Choose one)

Correct Answer: B

Rationale: The correct answer is B: Koilonychia. Koilonychia is a clinical sign associated with iron deficiency anemia characterized by spoon-shaped nails. This occurs due to the decreased production of hemoglobin, leading to changes in the nail bed. Fever (choice A) is not a typical sign of iron deficiency anemia. Rash (choice C) is not a common manifestation of this condition. Weight gain (choice D) is also not a typical sign, as iron deficiency anemia is more commonly associated with weight loss or failure to thrive. Therefore, choice B is the most appropriate sign to look for in a patient with iron deficiency anemia.

Correct Answer: B

Rationale: The correct answer is B because class II MHC proteins on donor cells are recognized by helper T cells, leading to the activation of cytotoxic T cells which then kill the donor cells. This process is crucial in graft rejection as it triggers an immune response against the foreign cells. Choice A is incorrect because class II MHC proteins are not receptors for interleukin-2. Choice C is incorrect as class II MHC proteins do not induce the production of blocking antibodies. Choice D is incorrect because class II MHC proteins do not induce IgE production, which is involved in allergic reactions, not graft rejection.

Correct Answer: C

Rationale: Complement fixation refers to the binding of complement components by antigen-antibody complexes. This process involves the activation of the complement pathway, leading to the formation of the membrane attack complex and subsequent lysis of target cells. Choice A is incorrect as it describes opsonization, not complement fixation. Choice B is incorrect as it refers to heat inactivation of complement. Choice D is incorrect as it does not involve complement fixation but rather describes the interaction of C3a with mast cells.

Correct Answer: C

Rationale: The correct answer is C: 1 week. Firstly, after initial exposure to an antigen, it takes time for the immune system to recognize and mount a response. This is known as the lag phase. Next, B cells need to be activated, differentiate into plasma cells, and start producing antibodies. This process typically takes a few days. Finally, the antibodies need to reach detectable levels in the blood, which usually occurs around 1 week post-exposure. Choices A, B, and D are incorrect because 12 hours is too short for the immune response to fully develop, 3 days may be sufficient for antibody production but not yet detectable levels, and 3 weeks is longer than necessary for detectable levels to be reached in a primary immune response.

Correct Answer: C

Rationale: Rationale for Correct Answer (C): When spleen cells from a donor mouse are injected into a genetically dissimilar recipient mouse, it can lead to a graft-versus-host reaction. This is because the recipient's immune system recognizes the donor cells as foreign and mounts an immune response against them. In this case, since the donor mouse is of strain A and the recipient is an F1 hybrid of strains A and B, the genetic disparity is significant, leading to a higher likelihood of a strong immune response from the recipient against the donor spleen cells. Summary of Incorrect Choices: A: The spleen cells being destroyed is less likely as the recipient's immune system would typically recognize and respond to foreign cells rather than simply destroy them. B: Spleen cells surviving without any effect is unlikely because of the genetic disparity between the donor and recipient mice. D: Inducing tolerance of strain A grafts in the recipient is less likely as a strong immune response is expected due to the genetic differences between