In autumn, people pile fallen leaves and put them in a compost pile. after several weeks, the pile becomes warm. where does the heat come from?

 The heat comes from the bacteria consuming readily decompose materials and the oxidation process heats up the compost pile from ambient air temperature. Bacteria consume carbon as a source of energy (to keep on eating) and nitrogen to build protein in their bodies (so they can grow and reproduce).

the cells uses some of the atoms of the glucose molecules to atp molecules. the atoms of the glucose molecules will then be converted into energy which will be eventually stored in atp. the energy produced which are stored in atp are coming from the glucose’s chemical bonds.