Pap smears are a test used only on women. Starting at about age 20, the woman's doctor will test the patient with a pap smear every 3 years (some women might need it more often than others). They test to see if there are any problems with the woman's cervix (the lower part of the uterus). Pap smears can identify infections as well as other problems, like abnormal cells that have the potential to transform into cervical cancer, a process that is linked to infection with Human Papilloma Virus (HPV), the most common STD in the country. Problems that pap smears detect usually aren't the woman's fault, such as the abnormal cells, however, being sexually active will increase the risk of having problems.
Mammograms are also a test used only on women. Starting around age 40, the woman's doctor takes an X-ray of the woman's breast about every year. These are called screening mammograms, and they are used to detect breast cancer in women who have shown no signs of the disease. Nobody knows what really causes cancer, or what they can do to stop it, however mammograms can give women a very early warning about the disease.
Prostate exams are used on men only. Also starting around age 40, and ending at age 75, the mans doctor puts his lubricated finger into mans rectum to see if the man is showing any signs of prostate cancer. Prostate cancer is caused by DNA inheritance, and it's usually not the mans fault if he acquires the disease.
Testicular Exams are also only used on men. Starting around the age of 15, and ending around 35, the male can have either a doctor conduct the test, or he can test himself. Usually testicular exams are done monthly once the male hits puberty. Testicular exams are to test for testicular cancer, a disease of which the cause is unknown, however age, race, and inheritance are all possible links to it.