Question

What is the role of the complement system in the body's defense?
A. It interferes with viral replication
B. It is involved with antibody production
C. It aids antigen presentation
D. It causes pathogen lysis

Answer 1

Hint: The complement system involves complement proteins which trigger a cascade of reactions. Such reactions and systems increase the efficiency of immune system cells and phagocytes.

Complete answer: Complement system is a part of the body's immune system.
It can enhance the ability of antibodies and phagocytes to remove damaged cells, microbes, pathogens from the system of an organism.
It may promote inflammatory reactions also.
When complement proteins get activated, it stimulates the phagocytes to clear foreign materials and damaged cells, inflammatory structures, and attracts more phagocytes.
Finally, the membrane attack complex or MAC destroys the pathogens by lysis of their membranes.

So, the correct option is D. It causes pathogen lysis

Note: The complement proteins are small proteins that are usually synthesized by the liver. These proteins circulate in the blood in inactive forms. There are three pathways in the complement system, viz. classical, alternative, and lectin pathway.