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Q25 - Summation and Inhibition Set the Threshold at Neuron 4

Theoretical A Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Nervous System Physiology

Sir John Eccles (1903-1997) and Sir Charles Sherrington (1857-1952) discovered the different roles of synapses, which dictate how neurons respond to stimulation from each other. Neurons 1, 2 and 3 were artificially fired, and their ability to initiate an action potential at point 4 was assessed.

Figure for Q25: Summation and Inhibition Set the Threshold at Neuron 4

Using the information and data, determine which of the statements are true or which are false.

A. Simultaneous stimulation from neurons (1) and (3) can fire (4).
B. Neuron (2) stimulates neuron (1).
C. The potential of (4) becomes more negative when (2) alone fires.
D. If (3) was fired twice in quick succession, (4) would fire.
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Question reproduced from IBO 2017, Theoretical Exam A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions