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Multiple Choice
Which statement best describes the all-or-nothing principle in cell signaling?
A
A cell's response to a stimulus is proportional to the strength of the signal.
B
A cell either fully responds to a stimulus once a threshold is reached, or does not respond at all.
C
Cells can partially respond to weak signals and fully respond to strong signals.
D
The response of a cell to a signal is always gradual and never abrupt.
Verified step by step guidance
1
Understand the concept of the all-or-nothing principle in cell signaling. This principle states that a cell's response to a stimulus is binary: it either fully responds once a specific threshold is reached or does not respond at all. There is no partial or gradual response.
Analyze the first option: 'A cell's response to a stimulus is proportional to the strength of the signal.' This suggests a gradual response, which contradicts the all-or-nothing principle. Therefore, this option is incorrect.
Evaluate the second option: 'A cell either fully responds to a stimulus once a threshold is reached, or does not respond at all.' This aligns perfectly with the definition of the all-or-nothing principle, making it a strong candidate for the correct answer.
Consider the third option: 'Cells can partially respond to weak signals and fully respond to strong signals.' This implies a graded response, which is inconsistent with the all-or-nothing principle. Thus, this option is incorrect.
Review the fourth option: 'The response of a cell to a signal is always gradual and never abrupt.' This directly contradicts the all-or-nothing principle, as the principle describes an abrupt, binary response. Therefore, this option is also incorrect.