AP BIOLOGY

Detailed explanation-1: -Overexpression of growth factors or a lack of suppressor proteins can lead to rapid uncontrolled cell division. As cells proliferate without regulation, tumors occur that can become deadly if not treated.

Detailed explanation-2: -Cancer is a disease caused when cells divide uncontrollably and spread into surrounding tissues. Cancer is caused by changes to DNA. Most cancer-causing DNA changes occur in sections of DNA called genes. These changes are also called genetic changes.

Detailed explanation-3: -Tumors, including cancers, are caused by abnormal cells that multiply continuously. If the abnormal cells continue to divide unstopped, they can damage the tissues around them, spread to other parts of the body (malignancy), and even result in death.

Detailed explanation-4: -With increasing cell growth, cancer cells spread or infiltrate to involve other organs, displacing normal tissue and severely depleting nutrient and metabolic resources, which results in death either from cancer cachexia or from mechanical disruption of normal organ function.

Detailed explanation-5: -Cancer is the result of unchecked cell division caused by a breakdown of the mechanisms that regulate the cell cycle. The loss of control begins with a change in the DNA sequence of a gene that codes for one of the regulatory molecules.