Which of the following gathers, organizes, and directs light through the specimen?

Correct Answer: C

Rationale: The correct answer is C: Condenser. The condenser gathers, organizes, and directs light through the specimen to improve contrast and resolution. It focuses the light onto the specimen, making it more visible. The other choices are incorrect because the ocular (A) is the eyepiece, the objective lens (B) magnifies the specimen, and the optical tube (D) holds the ocular and objective together.

Correct Answer: B

Rationale: The correct answer is B: RBC protection against oxidative damage. Glucose-6-phosphate dehydrogenase (G6PD) enzyme plays a crucial role in protecting red blood cells (RBCs) from oxidative damage by generating NADPH, which helps in neutralizing reactive oxygen species. G6PD deficiency leads to RBCs being more susceptible to oxidative stress, causing hemolysis. Choice A (Clotting factor production) is incorrect because G6PD is not directly involved in clotting factor production. Choice C (Platelet activation) is incorrect as G6PD deficiency does not affect platelet activation. Choice D (White cell proliferation) is incorrect as G6PD deficiency primarily affects RBCs, not white cell proliferation.

Correct Answer: C

Rationale: The correct answer is C because minor histocompatibility antigens, which are not matched in a 2-haplotype MHC-matched kidney transplant from a relative, can still trigger an immune response leading to graft rejection. This is why immunosuppression is still necessary. A: Graft-versus-host disease would not be a problem in this scenario as the recipient is receiving a kidney transplant, not bone marrow. B: This choice is redundant with the correct answer. Matching minor histocompatibility antigens is crucial for reducing the risk of rejection. D: Complement components do not play a significant role in graft rejection in this context.

Correct Answer: B

Rationale: The correct answer is B: vascular permeability. C3a and C5a are anaphylatoxins that can cause increased vascular permeability, leading to fluid leakage and inflammatory responses. They do not directly cause bacterial lysis (choice A), phagocytosis of IgE-coated bacteria (choice C), or aggregation of C4 and C2 (choice D). Increased vascular permeability is a key mechanism by which these complement proteins contribute to inflammation and immune responses.

Correct Answer: D

Rationale: The correct answer is D because the genes for the gamma chain and alpha chain are located on the same chromosome, making them linked genes. This is known as genetic linkage. The other choices (A, B, C) involve genes from different chromosomes or gene segments, so they are not linked genes. Genes that are physically close together on the same chromosome tend to be inherited together, which is the basis of genetic linkage analysis.