If decomposers go extinct on Earth:

1.	Detritivores will replace them
2.	Primary production will increase
3.	Nutrients will accumulate in dead plants and animals
4.	There will be no effect on carnivores

A chemical that enters living organisms primarily from the atmosphere is:

What is the best description of trophic efficiency?

Nitrogen fixation is carried out by:

What percent of the energy fixed by primary producers in a typical field ecosystem is received by a secondary consumer?

The rate at which energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances is called as:
1. biomass
2. transpiration
3. net primary productivity
4. gross primary productivity

The chemical energy that is not converted to new biomass in the process of energy transfer between trophic levels in an ecosystem is finally:
1. removed in the feces
2. recycled by decomposers
3. used by heterotrophs to thermoregulate.
4. dissipated into space as heat

The percent of the sun’s energy captured by plants is approximately:

Aquatic ecosystems that are most adversely affected by acid are those that lack:
1. calcium
2. carbonic acid
3. nitrate
4. bicarbonate

The largest net primary production of the Earth is contributed by:
1. savanna
2. salt marsh
3. open ocean
4. tropical rainforest