Final answer:
Agglutination is the clumping of cells, which when referring to red blood cells, is termed hemagglutination. This occurs when antibodies bind to antigens on the cells, and can be triggered by infections or autoimmune responses. In contrast, cancer cells lack contact inhibition and can form tumors.
Step-by-step explanation:
The process whereby cells stick together, forming clumps is known as agglutination. Specifically, when this clumping involves red blood cells, it is called hemagglutination. This phenomenon can occur due to the interaction between antibodies and antigens, where the antibodies bind to antigens on the surface of the red blood cells, leading to the aggregation of these cells. This may happen in response to certain infections when viruses or bacteria cause the immune system to produce antibodies or in certain diseases where antibodies are produced against self-red blood cells. Unlike normal cells which exhibit contact inhibition and stop dividing when they form a complete layer, cancerous cells lack this regulatory mechanism and may keep dividing, resulting in a tumor.