16. The protein, produced by B cells that binds to a specific antigen is

A. phagocyte
B. leukocyte
C. vaccine
D. antibody

17. Which of the following characteristics are common in lymphocytes, macrophages, and neutrophils?

A. They are all part of the nonspecific immune response in vertebrates
B. They are all part of the specific immune response in vertebrates
C. They are all part of the internal defenses of nonvertebrates
D. They are all types of white blood cells

18. Which of the following blood proteins can destroy pathogens?

A. Major histocompatibility complex
B. Platelets
C. Fibrinogen
D. Complement system

19. Which of these is part of the lymphoid system in humans?

A. Liver
B. Stomach
C. Tonsils
D. Kidneys

20. What type of B cell is like a tiny factory that produces antibodies identical to the B cell receptor that bind to the original antigen?

A. T cells
B. Memory cells
C. Plasma cells
D. Macrophages