1) Which of the following is a biotic factor of an ecosystem?

A) soil minerals

B) water

C) oxygen

D) bacteria

2) What is the term for movement of water and nutrients between biotic and abiotic portions of an ecosystem?

A) bio-cycling

B) biogeochemical cycling

C) decomposer-detrital cycling

D) energy cycling

3) One of the proposed solutions to global warming is to grow a large number of trees. This could be effective because:

A) trees would move carbon from CO2 in the atmosphere to organic molecules.

B) the gross primary production of trees moves CO2 into soil.

C) plant carbon is different from atmospheric carbon.

D) when decomposed, plant carbon is impossible to convert back to CO2.

E) plants are the base of all ecological food chains.

4) CO2 makes up about ________ percent of the atmosphere.

A) 0.035

B) 0.35

C) 3.5

D) 35

E) 37

5) Photosynthesizers take in carbon dioxide, whereas decomposers ________ carbon dioxide.

A) yield up

B) take in

C) destroy

D) fix

6) Nitrogen gas in the atmosphere is converted to forms of nitrogen usable by vegetation via:

A) assimilation.

B) denitrification.

C) fixation.

D) nitrification.

E) decomposition.

7) Why have legumes been planted as a cover crop to improve the soil fertility of a field?

A) Legumes aid organic decomposition.

B) The leaves of legumes absorb more nitrogen than other plants.

C) Legumes need about 100 times less nitrogen than other plants.

D) Legumes have carbon-fixing bacteria in their root nodules.

E) Legumes have nitrogen-fixing bacteria in their root nodules.

8) What major agricultural innovation in the early twentieth century allowed for production of far more food on arable land?

A) the discovery of crop rotation

B) use of fish as fertilizer

C) concentration of carbon fertilizer

D) industrial nitrogen fixation

E) genetically modified crops

9) Why are nitrogen and the nitrogen cycle important to living things?

A) Nitrogen is an essential part of all organic molecules.

B) Nitrogen is an essential part of proteins, RNA, and DNA.

C) Nitrogen is an important biotic component of ecosystems.

D) The release of nitrogen from fossil fuels counteracts global warming.

E) The release of nitrogen during cellular respiration contributes to global warming.

10) About how much of the atmosphere is composed of nitrogen?

A) 1 percent

B) 23 percent

C) 52 percent

D) 78 percent