Question

The white blood cells, which play a very important role in protecting the body against disease-producing organisms
A. Are larger in size and have nearly the same number as the red blood cells
B. Have the same size but are fewer in number than red blood cells
C. Are larger in size and fewer in number than red blood cells
D. Have the same size and number as red blood cells

Answer 1

The red blood cells or the erythrocytes are responsible for the transfer of the oxygen to the tissues via blood and white blood cells or leukocytes are the soldiers of the body that protect from the pathogens invading our body.

Complete step by step answer: Leukocytes or the white blood cells are found in the blood as well as in the lymphatic system. They are derived from the hematopoietic cells in the bone marrow. They are then classified into granulocytes or agranulocytes based on the content of the white blood cells or on the basis of cell lineage, as myeloid cells or lymphoid cells. Neutrophils, basophils and eosinophils are granulocytes, while monocytes and lymphocytes are agranulocytes. Monocytes and neutrophils are phagocytic cells that phagocytose the pathogen. The lymphocytes divide into T-lymphocytes, B-lymphocytes and natural killer cells. They help in antigen presentation, produce antibodies and produce cytotoxicity respectively to kill the pathogen. The size of the neutrophil and eosinophil is 10-12µm, basophil is 12-15 µm, small lymphocytes are 7-8 µm, large lymphocytes are 12-15 µm and monocytes are 15-20µm in diameter. The white blood cell count is between 4 × 109/L and 1.1 × 1010/L, while the red blood cells are mostly 6.2-8.2 µm in diameter and are around 20-30 trillion in the blood, i.e. 80% of all cells.
Hence, the correct answer is option C.

Note: Neutrophils, eosinophils, basophils and monocytes originate from the myeloid lineage and lymphocytes i.e., the T-cells, B-cells and NK cells originate from the lymphoid cell lineage. The granulocytes have granules in their cytoplasm, unlike granulocytes, it can be visible with the neutral, acidic and basic dye-stains in the microscope.