Chapter 8, Problem 8.1PS

True or False? Indicate whether each of the following statements about membrane transport is true (T) or false (F). If false, reword the statement to make it true.

(a) Facilitated diffusion of a cation occurs only from a compartment of higher concentration to a compartment of lower concentration.

(b) Active transport is always driven by the hydrolysis of high-energy phosphate bonds.

(c) The K_eq value for the diffusion of polar molecules out of the cell is less than 1 because membranes are essentially impermeable to such molecules.

(d) A 0.25 M sucrose solution would not be isotonic for a mammalian cell if the cell had sucrose carrier proteins in its plasma membrane.

(e) The permeability coefficient for a particular solute is likely to be orders of magnitude lower if a transport protein for that solute is present in the membrane.

(f) Plasma membranes have few, if any, transport proteins that are specific for phosphorylated compounds.

(g) Carbon dioxide and bicarbonate anions usually move in the same direction across the plasma membrane of an erythrocyte.

(h) Treatment of an animal cell with an inhibitor that is specific for the Na⁺/K⁺ pump is not likely to affect the uptake of glucose by sodium cotransport