Secondary Active Transport

Question

Secondary active transport
A) is not carried out by membrane proteins.
B) is not directly linked to the hydrolysis of ATP.
C) does not link the pumping of one substance to the concentration gradient of another.
D) does not require the cell to invest energy, either directly or indirectly.
E) cannot move a substance against its concentration gradient.

Accepted Answer

Secondary active transport is directly linked to the electrochemical gradient of one substance, which is used to drive the transport of another substance against its own concentration gradient. This electrochemical gradient is typically generated by the primary active transport of ions such as H+ or Na+. However, secondary active transport does not directly involve the hydrolysis of ATP, which is the source of energy for primary active transport. Instead, secondary active transport uses the potential energy stored in an electrochemical gradient that was established by primary active transport. Therefore, B is the correct answer, as secondary active transport is directly linked to the electrochemical gradient, but not the hydrolysis of ATP.