Marijuana contains the flowers, stems, seeds, and leaves of the hemp plant. To learn more about marijuana, take this quiz.

Substance-use disorder is also called drug addiction. It can break apart families, ruin personal relationships, and make it difficult to keep a job.

What happens to that cheeseburger and fries you had for lunch? During the digestive process, food is converted into energy that's used by your body. Take this quiz to see how much you know about how digestion works.

At any given time, millions of people in the U.S. are trying to lose weight. They spend billions of dollars each year on weight-loss products and services. Learn more about diets and weight loss by taking this quiz.

Anyone can get diarrhea. In fact, the typical American adult experiences diarrhea about 4 times a year. Most cases of diarrhea last a day or 2 and need no treatment. Find out more about this common digestive problem by taking this quiz.

The kidney's main job is to get rid of excess fluid and waste material in your blood. A person with kidney failure needs dialysis or a kidney transplant to survive. Learn more about dialysis by taking this quiz.

Cystic fibrosis (CF) is an inherited, often fatal disease of the body's mucus glands. It affects about 30,000 children and young adults in the United States, most of them descendants of people from northern Europe. Find out more about CF by taking this quiz.

True or false: More than 200 viruses cause colds.

Answer this one: The STD chlamydia is a bacterium that is transmitted through intimate physical contact. What's the most common means of transmission?

Death rates from cervical cancer are dropping, because more women are being screened. To learn more about cervical cancer and prevention, take this quiz.