7) How do nitrogen-fixing bacteria help cycle 340
nitrogen through ecosystems?
320
A. They change nitrogen into forms usable by
plants
300
1950
B. They convert water and carbon dioxide into
sugar
C. They release the chemical energy in nitrogen for respiration
D. They convert sunlight into chemical energy stored in nitrogen
19

A. They change nitrogen into forms usable by plants.

Explanation:

They change nitrogen into nitrous oxide and ammonia, a form usable by plants.

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amber has allowed scientists to study dna that has been preserved over millions of years.

primary succession occurs in essentially lifeless areas regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. secondary succession occurs