Qualified Medication Aides (QMA) Practice Exam

What is the primary function of white blood cells?

1. Transport oxygen throughout the body

2. Fight infection

3. Clot the blood after injury

4. Serve as energy sources

The correct answer is: Fight infection

The primary function of white blood cells, or leukocytes, is to fight infection. They play a crucial role in the immune system by identifying and eliminating pathogens such as bacteria, viruses, and fungi. White blood cells are essential for both the innate and adaptive immune responses. They can recognize foreign substances, initiate an inflammatory response, and produce antibodies to neutralize invaders. White blood cells include several different types, such as neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each with specialized functions in immune defense. For instance, neutrophils are typically the first responders to microbial infections, while lymphocytes are key players in the adaptive immune response, including B cells that produce antibodies and T cells that attack infected cells. The other options outline functions that are not associated with white blood cells. Transporting oxygen throughout the body is the role of red blood cells, which contain hemoglobin. Clotting of blood after injury is primarily mediated by platelets and clotting factors. Serving as energy sources refers to nutrients such as carbohydrates, fats, and proteins rather than cells involved in the immune response.