Answer:
How Does the Immune System Work?
Innate immunity: Everyone is born with innate (or natural) immunity, a type of general protection. ...
Adaptive immunity: Adaptive (or active) immunity develops throughout our lives. ...
Passive immunity: Passive immunity is "borrowed" from another source and it lasts for a short time.
Cell walls are supporting structures that help the plant to have a fixed shape and protect it from injury,animal cells do not need to keep the structures because they have the skeletal system to protect the organs and cushion them against any external injuries.