Final answer:
Apoptosis or programmed cell death can be triggered in a cell by DNA damage, developmental processes, loss of extracellular matrix contact, or immune system responses to preserve organism health and prevent diseases like cancer.
Step-by-step explanation:
Reasons for a Cell to Trigger Apoptosis
Apoptosis, or programmed cell death, is a vital process for the proper functioning and development of an organism. There are several reasons why a cell might be triggered to become apoptotic. First, cells that are damaged or have DNA abnormalities may undergo apoptosis to prevent potential harm to the organism. Second, cells that are no longer necessary, such as those only needed temporarily during developmental stages like embryonic development or metamorphosis, are programmed to die. Third, external signaling can induce apoptosis; for example, when a cell loses contact with the extracellular matrix, it may trigger a cascade resulting in cell death. Last, immune responses, like the elimination of T-cells that recognize "self" proteins to prevent autoimmune diseases, also involve apoptosis. These mechanisms ensure that only healthy and necessary cells persist, protecting the organism from disease and abnormal growth, such as cancer.