Which of the following is NOT a likely cause for species loss in marine ecosystems? 

A)  pollution 
B)  overfishing 
C)  habitat destruction 
D)  recreational fishing

Maximum sustained yield has helped prevent the collapse of most commercially valuable stocks of fish.

What have biologists learned from studying nature?

Which statement best describes a pumped-storage hydropower system? 

A)  It may vary in output during different seasons. 
B)  It is used to produce power during peak periods. 
C)  It involves the use of large dams. 
D)  It depends on stream flow to control power generation.

The construction of a nuclear power plant in a city would increase the inhabitants' concerns about the ________________________________________.

In which ecosystem would you be most likely to find a soil sample of closely packed pebbles that is a mixture of minerals and low in humus? 

A)  desert 
B)  tropical forest 
C)  coniferous forest 
D)  deciduous forest