During which process does a cell convert ADP to ATP?

a) Using energy to build a new protein

b) Capturing energy that was previously contained in a sugar molecule

c) Moving water from one side of a membrane to the other

d) Making a RNA molecule from a DNA template

The correct answer is B. capturing energy that was previously contained in a sugar molecule. The process by which ADP (adenosine diphosphate) is converted to ATP (adenosine triphosphate) is carried out the the mitochondria of cells. It is for this reason mitochondria are known as the powerhouse of the cell. As ATP reverts to ADP energy is released and is used in the cell for processes such as active transport.