In the wild, the only tiger subspecies in the wild that have been observed to carry the white color is the Bengal tiger. Even all the white tigers that have been held captive are partly Bengal in subspecies. It is believed that the rare recessive gene that carries the white color comes from Bengal tigers only.
It is difficult to classify viruses as living organisms because they are not made of cells. They only become alive when they find a host i.e. a living cell to live in.ome algae are difficult to classify because they sometimes do not properly fit in one of the kingdoms since they may have characteristics from a few of the kingdoms.
In addition, in order to spread the viruses also need to withstand the immune system. A special category of viruses is those that cause disease only when the immune system is deï¬cient in some way; these are called opportunists, and opportunistic infection is one of the main problems in patients with, for example, AIDS.irus spread control. Viral diseases can be prevented from spreading by vaccinations and the most successful of these is the small pox vaccine that has completely eradicated the disease in 1980. It is hoped that several other viruses, such as polio and measles, will follow.