Which of the following is characteristic of all leukocytes? B They are the most numerous of the formed elements in blood. D They are nucleated.
The correct answer and explanation is:
The correct answer is D. They are nucleated.
Leukocytes, or white blood cells, are a crucial component of the immune system. Unlike red blood cells (erythrocytes), which lack a nucleus, all leukocytes contain a nucleus. The presence of a nucleus allows them to perform essential immune functions, such as responding to infections, detecting and eliminating foreign substances, and producing antibodies. The nucleus of a leukocyte also houses its genetic material, which plays a key role in regulating cellular activities and enabling the cell to adapt to various immune challenges.
Leukocytes are categorized into two main groups based on the presence of granules in their cytoplasm: granulocytes and agranulocytes. Granulocytes, including neutrophils, eosinophils, and basophils, have visible granules in their cytoplasm that assist in fighting infections. Agranulocytes, such as lymphocytes and monocytes, do not have visible granules but are equally important in immune responses.
Regarding the other options:
- B. They are the most numerous of the formed elements in blood is not accurate. In fact, red blood cells (erythrocytes) are the most numerous formed elements in blood, outnumbering leukocytes by about 600 to 700 times. Leukocytes make up only about 1% of the total blood cell count, but their role in immunity is vital.
Leukocytes also exhibit significant diversity in their structure and function. Neutrophils, for example, are essential for the body’s defense against bacterial infections, while lymphocytes are key players in the adaptive immune system, responsible for recognizing and responding to specific pathogens. Monocytes, when matured into macrophages, are involved in the phagocytosis of pathogens and dead cells.
The nucleated nature of leukocytes allows them to perform their specialized tasks in a coordinated and efficient manner, helping protect the body from a wide range of pathogens.