What do all cells requiere a constant supply of

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a. the mitochondria b. the nucleus c. the vacuoles d. the endoplasmic reticulum

In the diagram here that represents the reaction, which reactant, a or b, is the limiting reagent?

What is the density, d, of a substance with a volume of v = 12.5 cm3 and a mass of m = 74.4 g ?