AP BIOLOGY

Detailed explanation-1: -Whereas apoptosis is a form of cell death that is generally triggered by normal, healthy processes in the body, necrosis is cell death that is triggered by external factors or disease, such as trauma or infection.

Detailed explanation-2: -Necrosis has been classically defined as an unprogrammed form of cell death that occurs in response to overwhelming chemical or physical insult. External forces that may lead to this accidental cell death include extreme physical temperature, pressure, chemical stress, or osmotic shock.

Detailed explanation-3: -The two classical types of demise can occur simultaneously in tissues or cell cultures exposed to the same stimulus and, often, the intensity of the same initial insult decides the prevalence of either apoptosis or necrosis.

Detailed explanation-4: -If cells are no longer needed, they commit suicide by activating an intracellular death program. This process is therefore called programmed cell death, although it is more commonly called apoptosis (from a Greek word meaning “falling off, ” as leaves from a tree).

Detailed explanation-5: -Apoptosis and necrosis are considered to be distinct modes of cell death; however, apoptosis can progress to secondary necrosis if apoptotic cells are not efficiently removed by phagocytic cells. Secondary necrosis was thought to be unregulated and to occur through passive cell swelling.