If muscle cells become more active than they usually are, they will grow more mitochondria. explain why
this happens.

When muscle cells become more active than they usually are, they will grow more mitochondria. Because the mitochondria are known as the powerhouse of the cell and they help to assimilate proteins as well as glucose to help execute cellular respiration and provide energy to the cell.

Explanation:

The mitochondria is an organelle that is encapsulated in a membrane inside the cell body. They are known as the powerhouse o energy source of the cell because they can produce cellular breathing by administering energy after assimilating glucose and proteins. Therefore, when muscle cells increase their activity they would increase the effort of the mitochondria and increase it as well. Muscle cells use a lot of energy to perform their effort. They also require a lot off the protein to be replaced when they die and to not die. As well as expel the heat generated from the effort and the mitochondria help in all those processes.

a physical change is being made.