Exam 46: Ecosystems

__________ soils hold the most amount of water.

Which gas is increasing the most in the atmosphere,thereby intensifying the greenhouse effect?  

Respond to the following statements with reference to the four steps of the nitrogen cycles listed below. -The conversion of gaseous nitrogen first to ammonia and then to other nitrogenous compounds involves this first step.

Respond to the following statements with reference to the four steps of the nitrogen cycles listed below. -The action of bacteria on ammonia in sewage treatment plants,ultimately converting it to nitrate,involves this process.

Approximately what percent of the energy that enters a trophic level becomes available to the next trophic level?  

Nitrification ____.  

Respond to the following statements with reference to the four steps of the nitrogen cycles listed below. -Nitrates from sewage wastewater must be converted to gaseous nitrogen by bacteria using this process.

In __________ food webs,most primary producers are eaten by primary consumers.

The ultimate factor affecting primary productivity is ____.  

Ecological efficiency is usually higher in aquatic ecosystems than on land,in part because photosynthetic protists do not make ____,as most land plants do.  

A(n)__________ is an area where all precipitation drains into a specific waterway,then on to groundwater,which becomes a source of water for plants.

Choose the one most appropriate answer for each. -Food chain

Which reservoir holds the largest volume of Earth's freshwater?  

The __________ is a sedimentary cycle; Earth's crust is the largest reservoir,and there is no major gaseous form.

Figure 46.2 The following question refers to the accompanying figure illustrating a tallgrass prairie food chain. -The letter D indicates the ____.  

Heterotrophs that obtain energy and carbon by feeding on both animal and plant materials are called ____.  

Figure 46.2 The following question refers to the accompanying figure illustrating a tallgrass prairie food chain. -The letter C indicates a ____.  

Which of the following is true about the length of food chains? 

In a __________,water,nitrogen,or carbon moves from the air,through organisms,then back to the environment.

Although Earth's ecosystems are remarkably diverse in their characteristics,they all run on energy captured by ____.