Hemolytic disease of the newborn caused by Rh blood group incompatibility requires maternal antibody to enter the fetal bloodstream. Therefore, the mediator of this disease is

Correct Answer: B

Rationale: The correct answer is B: IgG antibody. In hemolytic disease of the newborn, maternal IgG antibodies against fetal Rh-positive red blood cells can cross the placenta and attack the fetal RBCs, leading to hemolysis. IgE is primarily involved in allergic reactions, not hemolytic disease. IgM antibodies are too large to cross the placenta efficiently. IgA is not typically involved in hemolytic diseases. Therefore, IgG is the most likely mediator of hemolytic disease of the newborn in cases of Rh blood group incompatibility.

Correct Answer: B

Rationale: The correct answer is B: Both cell receptors and antibodies are highly specific in their actions. Cell receptors recognize and bind to specific molecules, triggering cellular responses. Antibodies are produced by the immune system to specifically target and neutralize foreign pathogens. This specificity is crucial for their functions. A, C, and D are incorrect: A: Cell receptors and antibodies are not produced by nerve cells. Cell receptors are typically found on the surface of various cell types, while antibodies are produced by B cells in the immune system. C: Cell receptors and antibodies do not slow the rates of chemical reactions. Their primary function is not to catalyze or inhibit chemical reactions. D: Cell receptors and antibodies are not directly involved in digestion. Digestion primarily involves enzymes and other digestive processes within the gastrointestinal tract.

Correct Answer: D

Rationale: Rationale for Answer D: 1. Scientific studies show higher allergies in cow's milk-fed babies. 2. Breast milk is the alternative in this scenario. 3. Breast milk is generally considered hypoallergenic. 4. Breast milk contains fewer potential allergens. 5. Thus, breast milk most likely contains fewer allergy triggers. Summary: A: Overgeneralization, not all infants react to cow's milk. B: Absolute statement, breast milk is not 100% effective against all allergies. C: Contradicts scientific findings, relationship exists between cow's milk and allergies.

Correct Answer: B

Rationale: The correct answer is B because early manifestations of AIDS include persistent fever, swollen glands, diarrhea, weight loss, and fatigue due to the immune system being compromised by HIV. Choice A is incorrect because HIV leads to a decreased, not elevated, white blood cell count. Choice C is incorrect as energy levels typically decline with AIDS progression. Choice D is incorrect as dry and scaly skin is not a common early symptom of AIDS.

Correct Answer: B

Rationale: The correct answer is B: Reddish-purple skin lesions. Kaposi's sarcoma is a type of cancer that is commonly seen in individuals with HIV/AIDS. The skin lesions associated with Kaposi's sarcoma are typically reddish-purple in color and can present as flat, raised, or nodular lesions. These lesions are caused by abnormal growth of blood vessels and can be found on the skin, mouth, or internal organs. Treatment options include radiation therapy, chemotherapy, or antiretroviral therapy. Choice A is incorrect because the onset of progressive dementia is more characteristic of the AIDS-dementia complex, which can occur as HIV affects the nervous system. Choice C, yellowing of the skin, is not a typical finding of Kaposi's sarcoma. Choice D, persistent cough, is not a direct symptom of Kaposi's sarcoma and is more commonly associated with respiratory conditions or infections.