Trophic Levels and Food Webs Answers

Energy is lost ascending each trophic level of the pyramid of energy. Therefore, when quaternary consumers eat tertiary consumers, most of the energy stored in the tertiary consumers' bodies is lost and only 10-15% is passed on to the quaternary consumers. Quaternary consumers, meanwhile, occupy the top position in the pyramid of energy because nothing preys upon them in turn.

Energy is lost at every transfer between trophic levels, such as through organisms' metabolism, heat, and waste. As a result, the least energy is available at the highest trophic level, which is occupied by quaternary consumers.

Predators help keep prey populations in balance. If a predator is eliminated, its prey may increase rapidly and consume more food than is available. When the food supply becomes depleted, some prey animals may starve.

Decomposers recycle the nutrients in dead organisms allowing it to completely travel through the food web cycle, from producer, to consumer and back again. Without decomposers, dead organic matter would accumulate in an ecosystem until it reached harmful levels. This recycling also applies to quaternary consumers, the predators that generally have no natural enemies, allowing the nutrients in their bodies to be recycled.

Trees are very large compared to the organisms they support, such as insects, birds and rodents. A single tree has much more biomass than the consumers depending upon it, meaning it is still the base of biomass pyramids and pyramids of energy. Therefore even if they are fewer in number trees still occupy the producer level of the trophic pyramid.

Primary consumers such as herbivores only feed on producers. Secondary consumers are predators and feed on primary consumers. The principal difference between the two trophic levels is what they consume.