Energy flow in ecosystems has 3 levels, there will be plants sent by the energy animals eat plants, step 1 is a 2 stage power tab in the contact card and they eat an animal's transportation, energy, step 3.
The power transfer system in a house, there are 3 levels in the plant energy transfer step 1 feed plants in the energy transfer step 2 and the animals that eat the energy transfer step 3.