A cell that requires a lot of energy might contain large numbers of

Mitochondria

Explanation:

The mitochondrion is a relatively small, double membrane organelle that primarily serves as the site of oxidative phosphorylation; a process that generates energy in the form of ATP for the running of cell's activities.

Hence, a cell that requires a lot of energy might need a large number of mitochondria in order to meet the energy demand of the cell.

The answer is mitochondria.

A cell that requires a lot of energy might contain large numbers of mitochondria.

Explanation:

Mitochondria are the cellular organelles that are responsible for producing the greatest amount of energy that cells require to activate their biochemical reactions. They produce adenosine triphosphate (ATP), which is an energy-carrying molecule and it's essential for the cell to perform its functions.