A Certain Kind of Cardiac Cell's Shift in Membrane Potential

question 125

Multiple Choice

A certain kind of cardiac cell's shift in membrane potential is seen using specialized electrodes. The graph below shows these modifications. The deflection indicated by the arrow is most likely caused by movement of which of the following ions?

• A)Sodium
• B)Potassium
• C)Calcium
• D)Chloride
• E)Sodium and potassium
• F)Calcium and potassium

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Definitions:

Enzyme

Biological catalysts which accelerate chemical reactions in living organisms by lowering the activation energy.

Racemic Acid

A mixture of equal amounts of two enantiomers of an acid, making it optically inactive.

Strecker Synthesis

A chemical reaction for synthesizing amino acids by reacting an aldehyde with ammonium chloride and potassium cyanide, followed by hydrolysis.

Racemic Alanine

A mixture of equal parts of the D- and L-enantiomers of alanine, making it optically inactive due to the internal compensation of optical activity.