Q22 - Predicting Action Potential Changes from Altered Ion Conditions
In an experiment, a researcher isolated a neuron and placed it in the standard Ringer solution (isotonic physiological solution). He measured the resting membrane potential of the axon, then stimulated the axon and measured its action potential (Record A, Figure Q.22). Subsequently, he repeated the experiment several times, each with a different modified Ringer solution. Figure Q.22 shows some of the results (Records B to E).
Figure 1.
Using the information and data, determine which of the statements are true or which are false.
A. If the modified Ringer solution contained a lower concentration of Na+ than the standard Ringer solution, the action potential is Record B.
B. If the modified Ringer solution contained a lower concentration of K+ than the standard Ringer solution, the action potential is Record C.
C. If the modified Ringer solution contained a substance that increased membrane permeability to K+, the action potential is Record D.
D. If the modified Ringer solution contained a substance that increased membrane permeability to Cl-, the action potential is Record E.
Question reproduced from IBO 2016, Theoretical Paper A, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)