HUMAN BIOLOGY

hUMaN iMpaCts oN the Biosphere 489

Given the numerous urgent ecological

issues raised in this chapter, it’s

no wonder that many people and

businesses are making efforts to

“go green.” If each of us finds ways

to live more sustainably, the future

will be brighter for all of us.

your Future

6. Earth’s biodiversity is threatened mainly by.
   a. the spread of disease organisms due to climate change
   b. habitat destruction by human activities
   c. disasters such as wildfires and hurricanes
   d. water pollution
   e. all of the above

CritiCaL tHinKinG

1. The map below shows the availability of direct solar energy
   in North America. Some areas are good candidates for solar
   heating systems and use of solar cells to produce electricity
   (see legend). What is the potential for using more solar
   energy where you live?
   3. Some people have proposed that all nuclear power plants
   in the United States be phased out over the next 20 years.
   Explain why you agree or disagree.

Available more than

Excellent 90% of the time

Available 80–89%

Very good of the time

Available 70–79%

Good of the time

Available 60–69%

Moderate of the time

Available 50–59%

Fair of the time

Available less than

Poor 50% of the time

© Cengage Learning

Bill Bachmann/Science Source

2. Some researchers and policymakers are proposing that we
   should protect entire ecosystems, such as forests, rather
   than just endangered species. Opponents say that this
   approach might endanger property values. Would you
   favor setting aside large tracts of land for restoration? Or
   would you consider such efforts too intrusive on individual
   rights of property ownership?

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