Respiration takes place in the mitochondria
Answer:
Oil
Explanation:
Since, unlike oil, source like wind, solar, water etc. come naturally we don't and can't replace them but when the viscosity in oil has been used up it must be change to allow the proper functioning of the machine.
The process of the development of reproductive cells in males is called Spermatogenesis. Spermatogenesis develops immature germ cells into mature sperm cells. Oogenesis is the process of the development of reproductive cells in females. Fertilization happens when the sperm and egg cells unite.
