One purpose may be to check for cancer. If abnormal cells are found, there might be something wrong...
Metastasis is the process of spreading cancer where the it spreads from one organ to another area of organ in the body. The cancer cells would break away from its original growth and move to other sites to grow tumors. However, this is not only limited to cancer. It can also happen with other diseases.
The answer is false. you do not have to
Soccer, football. They each have to depend on there teammates