Which of the following membrane activities requires energy from ATP hydrolysis? A) Movement of glucose molecules into a bacterial cell from a medium containing a higher concentration of glucose that inside the cell
B) Facilitated diffusion of chloride ions across the membrane through a chloride channel
C) Movement of sodium ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
D) Movement of water into a cell through aquaporins

Yes, you can get ap exam prep books that correspond to the exam you will be taking. i honestly think the ap biology exam was one of the easier exams to take.

You need to figure out at which x-value does the graph has a tangent line slope of -1.remember, the derivative is the slope of the tangent line. so find the derivative function and set it to equal -1 to find the x-value that will have a tangent line slope of 0.differentiate with the chain rule.    set the derivative to equal -1 and solve for x.      take log base 10 of both sides. also recall that  .    so the x-coord of the point of tangency is .the y-coordinate of this point of tangency can be calculated using the original function:     using point-slope form, the equation of the tangent line is      the x-intercept of this tangent line is when the graph is at y=0.    this rounds off to  .choice c.