Explanation:
protect cells and organelles from the surrounding environment
The organism would not have to find a partner in order to reproduce.
There is external and internal so I'll list th external. The most important is skin then mucus, sweat or secretion, hair, nails and tears which are all part of the integumentary. Some internal defenses are white blood cells and T cells.
The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid
