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The human cell will begin apoptosis when a toxin is released from the cell - VCE - SSCE Biology - Question 15 - 2020 - Paper 1
Question 15
The human cell will begin apoptosis when a toxin is released from the cell. an increase in the number of cells is required. the cell has been irreversibly dama... show full transcript
Worked Solution & Example Answer:The human cell will begin apoptosis when a toxin is released from the cell - VCE - SSCE Biology - Question 15 - 2020 - Paper 1
Step 1
a signalling molecule attaches to a death receptor on the plasma membrane of the cell.
Answer
Apoptosis, or programmed cell death, is a crucial process in cellular regulation and development. For a human cell to initiate this process, one important trigger is the attachment of a signalling molecule to a death receptor located on the plasma membrane. This binding activates intracellular pathways leading to a series of events resulting in cell death.
In the context of apoptosis, this signalling often involves the Fas ligand or tumor necrosis factor (TNF). Upon attachment, these signaling pathways lead to the activation of caspases, which are a family of protease enzymes. These caspases orchestrate the cellular dismantling required for apoptosis, ensuring that the cell undergoes controlled death without causing inflammation or damage to surrounding cells.
Step 2
a toxin is released from the cell.
Answer
While the release of a toxin can have deleterious effects, it does not typically trigger apoptosis directly. Instead, the cell usually experiences injury or stress as a result of toxic exposure, which might lead to necrosis (a form of accidental cell death) rather than apoptosis. Thus, this option is not a valid trigger for the initiation of apoptosis.
Step 3
an increase in the number of cells is required.
Answer
An increase in cell number contradicts the principle of apoptosis, as this process usually occurs when there are excess cells or when damaged cells need to be removed. Rather than being a trigger for apoptosis, a proliferation of cells typically necessitates the opposite: mechanisms to regulate and maintain homeostasis, potentially delaying apoptosis.
Step 4
the cell has been irreversibly damaged by very low temperatures.
Answer
Irreversible damage from extreme conditions, such as very low temperatures, could lead to necrosis rather than apoptosis. Apoptosis is a regulated and energy-dependent process occurring in response to specific signals, while cell injury from low temperatures does not align with the mechanisms of apoptosis.