Ecology 101 Answers

The predator/prey relationship is an interaction between two different species, so the organism, species and population levels are too low. The ecosystem and higher levels of organization deal with the interaction between biotic and abiotic factors, especially climate, but predation is a wholly biotic activity. The community level, meanwhile, specifically deals with interactions between members of different species.

Species are characterized by interbreeding between members of the group and by the absence of breeding with other groups.

Approximately 72% of Earth’s surface is covered by aquatic ecosystems, but they only account for supporting about 1/3 of the biosphere’s primary producers. This compares to terrestrial ecosystems which cover 28% of Earth’s surface yet account for the remaining 2/3 of the biosphere’s primary producers. Taken together this means terrestrial ecosystems are 5-6 times more productive than aquatic ecosystems per unit area.

Marine ecosystems generate 32% of the worlds primary producers, making seas and oceans responsible for almost 1/3 of the chemical energy produced in the biosphere. Because primary producers convert carbon dioxide into the oxygen animals breathe, it also means that marine ecosystems are responsible for generating a significant fraction of the oxygen in the atmosphere.

While temperate forests can get up to 60 inches of precipitation a year, rainforests receive 80 inches on average. Rainforests also enjoy a mostly constant temperature of about 75°F year-round, while temperate forests have four distinct seasons: spring, summer, fall and winter.