AP BIOLOGY

Detailed explanation-1: -This is called metastasis. 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.

Detailed explanation-2: -As cancer cells divide, a tumour will develop and grow. Cancer cells have the same needs as normal cells. They need a blood supply to bring oxygen and nutrients to grow and survive. When a tumour is very small, it can easily grow, and it gets oxygen and nutrients from nearby blood vessels.

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: -Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body.

Detailed explanation-5: -DNA Synthesis (S phase) In many cancer cells the number of chromosomes is altered so that there are either too many or too few chromosomes in the cells. These cells are said to be aneuploid. Errors may occur during the DNA replication resulting in mutations and possibly the development of cancer.