Chapter 42

In most ecosystems, the primary producers use energy from _______ to build organic compounds. a. inorganic chemicals b. sunlight c. heat d. lower trophic levels

Decomposers are commonly __________. a. fungi b. bacteria c. plants d. a and b

Organisms at the first trophic level ____________. a. capture energy from a nonliving source b. are eaten by organisms at higher trophic levels c. are shown at the bottom of an energy pyramid d. all of the above

Primary productivity on land is affected by ______________. a. nutrient availability b. amount of sunlight c. temperature d. all of the above

A(n) __________is an autotroph. a. primary producer b. herbivore c. detritivore d. top carnivore

Most of earth's fresh water is ___________. a. in lakes and streams b. in aquifers and soil c. frozen as ice d. in bodies of organisms

Earth's largest carbon reservoir is ____________. a. the atmosphere b. sediments and rocks c. seawater d. living organisms

Carbon is released into the atmosphere by ____________. a. photosynthesis b. aerobic respiration c. burning fossil fuels d. b and c

Greenhouse gases ___________. a. help keep Earth's surface warm enough for life b. are released by natural and human activities c. are at higher levels than they were 100 years ago d. all of the above

The ______________ cycle is a sedimentary cycle. a. phosphorus b. carbon c. nitrogen d. water

Earth's largest phosphorus reservoir is ___________. a. the atmosphere b. bird droppings c. sediments and rocks d. living organisms

Plants obtain __________ by taking it up from the air a. nitrogen b. carbon c. phosphorus d. a and b

Which holds the least carbon? a. soils b. the air c. seawater d. rocks

Match each term with its most suitable description. _________carbon dioxide _________bicarbonate _________ammonium _________nitrogen gas a. contains triple bond b. product of nitrogen fixation c. marine carbon source d. greenhouse gas