Question

Why is mitochondria called power house of cell ?

Answer 1

Because it is the site of cellular respiration in which nutrients are break down and convert into energy rich molecules for cell  

Answer 2

1) Cellular respiration in prokaryotic cells like that of bacteria occurs within the cytoplasm.

2) In eukaryotic cells cytoplasm and mitochondria are the sites of reaction.

3) The produced energy is stored in mitochandria in the form of ATP.

4) Hence, mitochondria are called "Power houses of cell".