Homework Help: Functions/Logarithims

Posted by Steph on Thursday, March 8, 2012 at 8:35pm.

Energy is needed to transport a substance from outside a living cell to inside the cell. This energy is measured in kilo calories per gram molecule, and is given by
E = 1.4 log (C1) / (C2
where C1 represents the concentration of the substance outside the cell, and C2 represents the concentration inside the cell.

a) Find the energy needed to transport the exterior substance into the cell if the substance inside the cell is double the concentration outside the cell.

b) What is the sign of E if C1 < C2? Explain what this means in terms of the cell.

(Please show all your work to answer this question! Thank you so much!)

Functions/Logarithims - Steve, Friday, March 9, 2012 at 11:09am
Replace C2 by 2C1
E = 1.4 log 2C1/C1 = 1.4 log 2

If C1<C2 then C1/C2 < 1 and the log is < 0

I assume negative energy needed means energy is released.
Functions/Logarithims - PS - Steve, Friday, March 9, 2012 at 11:10am
Oops - got the fraction upside down. 1.4 log 1/2

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