Why does active transport require energy to move molecules of a substance across a cell membrane?

Question

• a
• b
0 c
Lack of the substance makes the cell weak.
The cell membrane is very thick.
The substance moves from low to high concentration, against the concentration gradient.
The substance moves from high to low concentration, with the concentration gradient.

Answer 1

Active transport requires energy to move molecules of a substance across a cell membrane because the substance moves from low to high concentration, against the concentration gradient.

In this process, energy is needed to work against the natural tendency of molecules to move from an area of higher concentration to an area of lower concentration, which is the case in passive transport.