2026 Anatomy and Physiology Practice Test – Complete Prep for Students

Iron is essential for making hemoglobin, the oxygen-carrying protein in red blood cells. When iron is lacking, hemoglobin synthesis falls, red blood cell production drops, and the blood’s ability to deliver oxygen to tissues decreases—this is anemia. The other options describe abnormalities of white blood cells or platelets, or an excess of red cells, which aren’t caused by iron deficiency. In iron deficiency anemia, the red cells are typically small and pale (microcytic, hypochromic).