Large quantities of nutrients are bound tightly in
________ structure; they are not readily
available until released by the activities of
Some nutrients are ________ from the soil and
carried out of ecosystems by underground
water flow to streams.
The element ________ is a basic constituent of
all organic compounds and is involved in the
fixation of energy by photosynthesis.
The difference between the rate of carbon
uptake in photosynthesis and the rate of carbon
loss due to autotrophic and heterotrophic
respiration is the net ________ productivity.
Nitrogen is generally available to plants in only
two forms: ammonium and ________.
Biological nitrogen fixation is accomplished by
symbiotic ________ living in mutualistic
association with plants.
Nitrogen can be returned to the atmosphere
when certain bacteria convert it from nitrate into
nitrogen gas, which is a process called
Microbial decomposition of organic matter
results in NH
+ production through a process
Nearly all of the phosphorus in terrestrial
ecosystems comes from the ________ of
calcium phosphate minerals.
___________ develop as a result of incomplete
decomposition of organic matter in swamps and