* Muscle cells: Muscle cells need lots of energy for contraction.
* Nerve cells: Nerve cells use energy to transmit signals.
* Liver cells: Liver cells are involved in many metabolic processes, which require energy.
* Sperm cells: Sperm cells use energy to swim to the egg.
* Kidney cells: Kidney cells need energy to filter blood.
The reason why these cells need so many mitochondria is because mitochondria are the "powerhouses" of the cell. They are responsible for converting food into energy that the cell can use.
So, if a cell needs to perform a lot of work, it will need lots of mitochondria to provide it with the energy it needs.
