Chapter 42

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

Organisms at the first trophic level ___________. a. fungi and bacteria b. plants c. animals d. green algae

Organisms at the first trophic level ____________. a. capture energy from a nonliving source b. are eaten by organisms at lower trophic levels c. are shown at the top of an energy pyramid d. are consumers

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. 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 only by human activities c. have decreased since the industrial revolution

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. water

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

Soil in ____________ is richest in carbon. a. the arctic b. the tropics c. temperate zones

Match each term with its most suitable description. $$ \text {_____ carbon dioxide } \quad \quad\quad\quad\quad \text {a. contains triple bond } $$ $$ \text {_____ bicarbonate} \quad \quad\quad\quad\quad \text {b. nutrient taken up by plant roots} $$ $$ \text {_____ nitrate} \quad \quad\quad\quad\quad \text {c. marine carbon sources } $$ $$ \text {_____ nitrogen gas} \quad \quad\quad\quad\quad \text { d. greenhouse gas} $$