What Is Life? 2nd Edition by Jay Phelan

Exercise 46

Nitrogen enters the food chain:
A) primarily through soil-dwelling bacteria that "fix" nitrogen by attaching it to other atoms.
B) from the atmosphere when "fixed" by the photosynthetic machinery of plants.
C) when rocks dissolved by rainwater become soil, which is then utilized for plant growth. 54
D) through soil erosion followed by runoff into streams and ponds.
E) through methane, produced by herbivores as a by-product of the breakdown of plant material.