6. The Membrane

Active transport requires an input of energy and can also generate voltages across membranes. Based on this information, which of the following statements is true?

Which of these is an example of active transport?

Which of the following correctly describes a general property of all electrogenic pumps?

Glucose can be moved into cells via an active transport mechanism when the concentration of glucose inside the cell is higher than the concentration of glucose outside the cell. This active transport mechanism moves glucose and sodium into the cell at the same time. The glucose moves up its gradient and the sodium moves down its gradient. Which of the following statements about this mechanism is accurate?

Consider the transport of protons and sucrose into a plant cell by the sucrose-proton cotransport protein. Plant cells continuously produce a proton gradient by using the energy of ATP hydrolysis to pump protons out of the cell. Why, in the absence of sucrose, do protons not move back into the cell through the sucrose-proton cotransport protein?

Which of the following statements about cotransport of solutes across a membrane is correct?