IB Biology Exam Prep

Answer: E, Neutrophils. About 60% of all white blood cells are neutrophils.

Key Takeaway: All white blood cells comprise the body’s primary defense against foreign agents. When a foreign agent is detected, neutrophils and other white blood cells are recruited by body signals, and serve to destroy the foreign agent through a variety of processes. The lymphocyte is the second most common type of white blood cell, and is also a key constituent of the immune system.

Photos: Neutrophil and Anthrax (GNU Wikimedia Commons)
Neutrophil smear (Tommaso Leonardi)