Question

Which of the following BEST explains whether cotransport is an active process or a passive process? A. It is active because ATP is needed to transport both chemicals across their concentration gradients.B. It is active because ATP is needed to establish a concentration gradient for one chemical to power the transport of the other chemical.C. It is passive because both chemicals move down their concentration gradients.D. It is passive because the movement of one chemical powers the movement of the other chemical.

Answer 1

The cotransport of melecules across a cell membrane is active process that requires energy to moves substances as glucose against a gradient in concentracion or in electrical potencial provided by the movement of other molecule along its gradient of concentracion. This process occurs in the SGLT transport (sodium-glucose), which couples the movement of sodium into the cell down its electrochemical gradient to the movement of glucose against its concentracion gradient. Its is know as a secondary active transport being divided in a driving ion (sodium in the example) and a driven ion (glucose). Therefore, the alternative that best define the cotransport is the letter B.