The mitochondria is the powerhouse of the cell. It generates the cell's energy (ATP) and maintains the cell's metabolism. Without the mitochondria, the cell would not be able to produce this energy or regulate the cell's metabolism. Thus, without the mitochondria the cell would die.
Ptolemy could not explain * Retrograde motion of the planets* with out epicycles and deferents.
A. The lighter wagon will move faster, since there is no change in force to make up for the increase in mass.
The interstitial fluid is the fluid that moves around in the circulatory system of a typical arthropod. Arthropods have an open circulatory system, which pumps blood into a cavity called hemocoels that sorrounds the organs and then returns to the heart through ostia (openings). They contain hemolymph which is a mixture of blood and the interstitial fluid.