Niche - the way of life of an organism.
Energy enters an ecosystem from the sun and flows betweem organisms as one eats another.
Energy is always lost from one trophic level to the next. Producers - autotrophic organisms using solar or chemical energy to produce all the organic nutrients for an ecosystem. Consumers - heterotrophic organisms that cannot make their own food. They get energy from the chemical bonds in the nutrients they eat. Omnivores - eat both plants and animals.