A patient with chronic kidney disease has hyperphosphatemia. What is a commonly associated electrolyte imbalance?

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: The correct answer is D because antibodies do not have a single, defined amino acid sequence due to variability in their structure. This variability is a result of somatic recombination and hypermutation. A: Antibodies can fix complement, leading to the destruction of pathogens. B: Antibodies are produced by B-lymphocytes and can occur on their surface as B-cell receptors. C: Antibodies predominate the secondary immune response, not the primary response, as memory B-cells are generated during the primary response for a quicker and more robust secondary response.

Correct Answer: D

Rationale: The correct answer is D because the class of an immunoglobulin is determined by the type of heavy chain it possesses. There are five main classes of immunoglobulins (IgG, IgA, IgM, IgD, IgE) which are defined by the heavy chain constant region. Different heavy chain types result in different effector functions and biological properties. Choices A, B, and C are incorrect because the class of an immunoglobulin is not determined by Class I and Class II major histocompatibility complex proteins, carbohydrate attached to the light chain, or the antigen. These factors may influence the function or specificity of the antibody, but they do not determine its class.

Correct Answer: C

Rationale: The correct answer is C: Carefully splint the leg as it is. This is the most appropriate immediate action because splinting the leg as it is will help stabilize the fracture and prevent further injury or damage to surrounding tissues. Moving or straightening the leg (option D) could worsen the fracture and cause more pain. Positioning him flat on his back (option A) may not provide enough support and could lead to additional complications. Applying a tourniquet (option B) is not necessary and could potentially cut off blood flow to the leg, causing more harm. Splinting the leg as it is will help maintain alignment and reduce the risk of further damage until proper medical care can be provided.

Correct Answer: B

Rationale: The correct answer is B because IgG, not IgM, is the best at facilitating phagocytosis through the Fc receptor. IgM is the best at activating complement (A), antibodies can neutralize bacterial toxins (C), and antibodies can inhibit binding of toxins to their receptors on host cells (D). IgM primarily activates complement, while IgG is more efficient at facilitating phagocytosis through the Fc receptor. This distinction is crucial in understanding the functions of different immunoglobulins.