Figure 4.2i Resting potential results. Red marks are resting potentials measured by a student at four different [K⁺]_o. The orange mark is the resting potential measured in normal saline after completion of the entire experiment. The green mark is the resting potential at [Na⁺]_o of 104 mM. The blue marks show the Nernst potential of K⁺ at each concentration. This line has a slope of 58, while the student data have a slope of 37. Such a disparity is common. Error bars were omitted here for clarity, but the students should include ± standard deviation on their graphs. K⁺ concentrations correspond to 5.4, 10.8, 21.7, 32.4, and 60 mM.