Chapter 42

In most ecosystems, 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 \(\mathrm{d} \cdot \mathrm{a}\) and \(\mathrm{b}\)

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

\(\mathrm{A}(\mathrm{n})\) _________ is an autotroph. a. 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. include nitrous oxide and carbon dioxide \(\mathrm{d}\). 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

Most plants obtain __________ by taking it up from the air. a. nitrogen b. carbon c. phosphorus \(\mathrm{d} \cdot \mathrm{a}\) and \(\mathrm{b}\)

Nitrogen fixation converts ______ to _______ . a. nitrogen gas; ammonia b. nitrates; nitrites c. ammonia; nitrates d. nitrites; nitrogen oxides

Soil in _________ is richest in carbon. a. the arctic b. the tropics c. temperates zones

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