Apoptosis differs from necrosis in that necrosis: a. requires the reception of an extracellular signal. b. causes DNA to fragment. c. causes cells to swell and burst, whereas apoptotic cells shrink and condense. d. involves a caspase cascade

c. causes cells to swell and burst, whereas apoptotic cells shrink and condense

Explanation:

These two mechanism are responsible for death of cells in multi cellular organisms.Apoptosis is  naturally occurring process which is well organised and programmed.It is ensures the  automatic death of old and worn out cells, needed for certain cellular developments. This is demonstrated by DNA fragmentation,cell shrinkage,and the break down of the nuclear walls.It can be initiated through two pathways of intrinsic and extrinsic,The latter leads to death from internal factors,while in the former is when external factor causes the death .

However,when cell death is influenced by external factors(toxins)  in the cell environments,which lead to unpredictable or unregulated process leading to cell death ,the process is called Necrosis.it is demonstrated with the swelling and busting of the cell.and characterised with inflammation. It is an accidental death which causes injuries to the cells and tissues.

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.

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