The respiratory centre in the human brain is located in the: MCQ with Answer and Explanation

Explanation:
Innate immunity is the non-specific, inborn defense mechanism present from birth. It includes physical barriers (skin, mucous membranes), physiological barriers (stomach acid, tears), cellular barriers (neutrophils, macrophages), and cytokine barriers (interferons). Antibodies and memory cells are part of acquired (adaptive) immunity.

Explanation:
Hematopoiesis is the production of formed elements of blood (red cells, white cells, platelets) from hematopoietic stem cells in the bone marrow. Hemolysis is RBC destruction, hemostasis is stopping bleeding, hematuria is blood in urine. Erythropoietin stimulates RBC production.

Explanation:
Vitamin B₁₂ contains a cobalt ion at the center of its corrin ring structure, hence the name cobalamin. It is essential for DNA synthesis and nervous system function. Iron is in heme, magnesium in chlorophyll, zinc in many enzymes. B₁₂ is unique in having a metal-carbon bond.