Humans have dramatically altered the rate of nitrogen fixation into forms usable by autotrophs ________
A) by producing synthetic fertilizers and applying them to crops, lawns, and parks
B) due to the burning of fossil fuels to meet our energy needs
C) because of the erosion of farmlands through poor agricultural practices
D) by using antibiotics to reduce the numbers of denitrifying bacteria
E) by selectively removing leguminous plants
A
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The main current in Antarctic waters is the Antarctic Circumpolar Current, also called the West Wind Drift.
a. true b. false
The speed of all ocean waves is controlled by ____________, ____________, and ____________ ____________. Fill in the blank(s) with the appropriate word(s)
In a tropical rain forest, dropped leaves, fallen trees, and dead animals decompose ____.
A. quickly due to the abundance of decomposers B. slowly due to the nutrient-poor soils C. slowly due to the abundant rainfall D. moderately and nutrients are taken up by the roots of the lianas E. quickly due to the dense ground vegetation
What is significant about the North American Boreal Forest?
A) also known as a taiga or "snow forest" B) nursery to 3 billion birds C) regulates climate and carbon levels D) rising temperature is biggest threat E) all of the above