The diagram shows a cell membrane with carrier proteins transporting molecules from a region of low concentration outside the cell to a region of high concentration inside the cell. Energy is supplied by respiration within the cell.
Explain why energy is needed for the movement of molecules shown in the diagram.
Show answer, mark scheme and Mentor explanation
MP1: Energy is needed because molecules are being moved against their concentration gradient from low to high concentration.
MP2: Energy is supplied by respiration within the cell to power the carrier proteins for active transport.
Can you spot the two exact ideas the mark scheme wants here?
To gain both marks, your explanation needs two linked points. First, say that energy is needed because the molecules are moving against the concentration gradient, from a low concentration to a high concentration. Second, state that this energy is supplied by respiration within the cell and is used to power the carrier proteins for active transport.