Biological Organisms: Living things that are capable of reacting to stimuli, reproduction, growth, and homeostasis. Organisms are classified by taxonomy into specified groups such as the multicellular animals, plants, and fungi; or unicellular microorganisms such as a protists, bacteria, and archaea.
Answer: it's because they need to provide a lot of energy.
Explanation: fat cells have many mitochondria because they store a lot of energy. Muscle cells have many mitochondria, which allows them to respond quickly to the need for doing work.