1) Producers like plants convert light or chemical energy into food through photosynthesis or chemosynthesis. A food chain shows how matter and energy pass between organisms. A food web shows multiple interconnected food chains in an ecosystem. 2) An energy pyramid displays the available energy at each trophic level. Only about 10% of energy is transferred between levels, so the amount decreases going up the pyramid. This limits the length of food chains. 3) There are more mice than hawks in a grassland because energy transfers inefficiently between trophic levels in food chains, according to the energy pyramid model.