The cross-sectional area of the channel of a stream or river is calculated by:

A) multiplying the channel's width by its average depth
B) multiplying the channel's depth by its average length
C) dividing the channel's depth by its width
D) adding the channel's width and average length

A(n)______________ ________________ contains a diverse array of species,including more than half of the world's terrestrial plants and animals.

Which statement would likely be made by a proponent of population regulation? 

A)  People are the world's most valuable resource. 
B)  If a person produces more than he consumes, he is an asset. 
C)  One-sixth of the population does not have the basic necessities. 
D)  Human ingenuity permits continued improvement in humanity's lot.

Research has indicated that long-term exposure to some chemicals at low doses may disrupt the immune,nervous,and endocrine systems of humans.

What percentage of the insecticides applied to crops by aerial spraying actually reaches the target pests? 

A)  about 50% 
B)  about 25% 
C)  about 10% 
D)  about 1%

What causes large fish kills and contamination of drinking water in most developed countries? 

A)  oxygen levels rising in cooler waters 
B)  increased water temperatures from industrial plants 
C)  sewage treatment plants with holding ponds 
D)  accidental release of toxic industrial chemicals

The natural heating of the Earth is the result of _________________________ being trapped in the lower atmosphere.

High-strength plastics and composite materials strengthened by carbon and glass fibres are advantageous because they are stronger than metal and easily moulded into any shape.

Which of the following materials has high porosity and high permeability?

A) unfractured granite
B) well-sorted gravel
C) compacted clay
D) uncompacted clay
E) poorly sorted sand, silt, and clay

Low-quality matter is often deep underground.