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This model shows how energy is stored when sunlight shines on green plants and how it is released during respiration. It shows the importance of oxygen because energy is NOT stored in the food, but in the fuel-oxygen system. Use this model to accompany /teaching-resource/resource-11094177
We say “food ‘contains’ energy” however it is only when it combines with oxygen that energy becomes available. Digestion gets food into the blood, breathing gets oxygen in the blood, these two combine in the cells of our bodies to provide energy: the products are carbon dioxide and water. So our food exits our body mainly through the nose! Oxygen is a dangerously reactive gas, with weak chemical bonds holding the atoms together. Fuels and food by contrast are strongly bonded. The energy from respiration comes from replacing the weak bonds in oxygen with the strong bonds in carbon dioxide and water - these are the products of respiration and the starting materials for photosynthesis. During photosynthesis the spring is re-set as this model shows.