1. The trophic level is something's position in the food chain/food web.
2. Energy travels through out the food chain because all the animals eat each other and take each other's energy. The decomposers are eaten, the producers are eaten, but the primary consumers get all the energy.
3. The energy decreases because each animal decomposes the energy a little, before getting eaten. By the time the food reaches the top of the web, the energy is barely left.
Hope this helps!
