Exothermic and endothermic reactions work together to supply energy.
Endothermic and exothermic reactions can form a cycle.
Example: The energy stored by the series of endothermic reactions in photosynthesis can be released by exothermic reactions such as combustion.
A plant absorbs energy from the sun during photosynthesis. 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Endothermic Equation If the plant burns, the energy is released. C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O Exothermic Reaction Combustion Page 90
Section 3.4 Life and Industry Depend on Chemical Reactions