Of the main nutrients in the biosphere, the one that is fixed inside nodules in certain plant roots is ________.
A) carbon
B) nitrogen
C) oxygen
D) hydrogen
E) calcium
Question 2
Which of the following is NOT a source of atmospheric oxygen in the oxygen cycle?
A) The weathering of rocks
B) The burning of fossil fuels
C) Water from plant transpiration
D) Decomposition of water during photosynthesis
E) Decomposition of nitrogen by solar energy
