population soil

How do trees prevent soil erosion?

• Trees keep the wind from blowing hard through an area.

• The leaves keep rain from striking the ground hard
  

• Roots of the trees hold the soil together
  

• All of the above

Soil erosion

• is a natural process and as such should be left alone.
  

• has been accelerated by human activities.
  

• is an aesthetic problem but does not real damage to human society.

• none of these

Which of the following is an agent of soil erosion?

• water
  

• wind
  

• gravity
  

• all of the above

Farming causes soil erosion because

• the land is uncovered by plants for part of the year.
  

• farm machines churn up the soil.
  

• crop plants are often less able to protect the land than native plants.

• all of these.

____________ animals cause soil erosion because they churn up ground with their hooves.

Besides removing trees, logging removes ____________, the dead leaves, that protect forest floors from erosion.

____________ agriculture clears tropical rainforests and leaves land open for erosion.

Hazardous waste includes substances that are:

• toxic
  

• corrosive
  

• flammable
  

• all of the above

Which of the following is NOT considered a potentially hazardous material?

• baking soda

• batteries
  

• fertilizers

• paint

Nations that produce the most hazardous waste

• have the most people.
  

• have the most industry.

• have the most farmers.

• have the most buildings.