What is the recommended cleaner for removing all oil from objective lens?

Correct Answer: A

Rationale: The correct answer is A: 70% alcohol or lens cleaner. Alcohol is recommended as it effectively removes oil without damaging the lens. Step 1: Apply alcohol on a clean cloth. Step 2: Gently wipe the lens in a circular motion. Alcohol evaporates quickly, leaving no residue. Xylene (B) is too harsh and can damage the lens. Water (C) can cause streaks and not effectively remove oil. Benzene (D) is toxic and should never be used on optical lenses.

Correct Answer: D

Rationale: The correct answer is D because RBC precursors are located surrounding macrophages near the sinus membrane in the bone marrow. This location allows for the interaction between macrophages and developing RBCs, facilitating the removal of nuclei from maturing RBCs. Choices A, B, and C are incorrect because RBC precursors are not typically found in the center of hematopoietic cords, adjacent to megakaryocytes, or surrounding fat cells in apoptotic islands in the bone marrow.

Correct Answer: B

Rationale: Step-by-step rationale for the correct answer (B): 1. Low Hb (120 g/L) and MCV (69 fL) indicate microcytic anemia. 2. High WCC (14.9 x 10^9/L) suggests an inflammatory response. 3. Ferritin (18 ng/mL) is low, indicating iron deficiency. 4. Symptoms of blood in stools, fatigue, weight loss are concerning for colorectal cancer. 5. Therefore, the correct diagnosis is iron deficiency anemia due to colorectal cancer. Summary of incorrect choices: A: Iron deficiency anemia due to poor diet - Ferritin levels would typically be low in this case, but other results do not support this choice. C: Vitamin B12 deficiency due to pernicious anemia - MCV is low, not high as expected in vitamin B12 deficiency. D: Thalassemia due to genetic mutation - Thalassemia would present with microcytic anemia

Correct Answer: B

Rationale: The most likely diagnosis for the patient is B: Hodgkin lymphoma. The symptoms of fever, night sweats, and painful lumps in the neck/armpits are classic signs of Hodgkin lymphoma. The Reed-Sternberg cells seen in Hodgkin lymphoma are characteristic and differentiate it from non-Hodgkin lymphoma. Infectious mononucleosis typically presents with sore throat and fatigue, not painful lumps. Tuberculosis usually manifests with respiratory symptoms. Non-Hodgkin lymphoma may present similarly, but the presence of Reed-Sternberg cells points towards Hodgkin lymphoma.

Correct Answer: C

Rationale: Step 1: Hypersensitivity to penicillin and poison oak is due to hapten-protein complex formation. Step 2: Haptens are small molecules that bind to proteins, triggering an immune response. Step 3: This immune response can lead to sensitization and subsequent hypersensitivity reactions. Step 4: IgE antibody is typically involved in Type I hypersensitivity reactions, not haptens. Step 5: IgG and IgM antibodies are more associated with Type II and Type III hypersensitivity, not haptens. Step 6: Th-2 cells are involved in Type IV hypersensitivity reactions, not haptens. Summary: Choice C is correct as hypersensitivity to penicillin and poison oak is initiated by haptens, not IgE antibodies (Choice A), IgG and IgM antibodies (Choice B), or Th-2 cells (Choice D).