AP BIOLOGY

Detailed explanation-1: -Unlike normal cells, cancer cells don’t stop growing and dividing when there are enough of them. So the cells keep doubling, forming a lump (tumour) that grows in size.

Detailed explanation-2: -Most cancer-causing DNA changes occur in sections of DNA called genes. These changes are also called genetic changes. A DNA change can cause genes involved in normal cell growth to become oncogenes. Unlike normal genes, oncogenes cannot be turned off, so they cause uncontrolled cell growth.

Detailed explanation-3: -Genes that normally block cell cycle progression are known as tumor suppressors. Tumor suppressors prevent the formation of cancerous tumors when they are working correctly, and tumors may form when they mutate so they no longer work.

Detailed explanation-4: -One likely reason for spontaneous regression is that the body triggers an immune response against specific antigens displayed on the surface of tumour cells.