HAP T ERE LEV E N
Chapter 11-12:
Ph
ru
1
Although nitrogen and carbon exisl as gases, certain elements
Ihat cycle in the biosphere do not exist in gaseous form. These
elements accumulate in rocks and soil, and participate in what
are called biogeochemical cycles.
Among the elements Ihat undergo sedimentary cycles are calcium, sulfur, magnesium, and phosphorus. As you will see in this
plate, phosphorus is one of Ihe key elements in organic matter.
producer in the phosphorus cycle. The
phosphate is
in plant tissues Ie), and then the
is
(D) by an animal, which is seen
(E).
Phosphates are returned to the lake when
plants and animals die.
waste IF) and
waste (Gl return phosphate
to the water. Once again it may be reabsorbed by plants that line
the lake, and it enters the cycle again.
Phosphorus is one of the critical elements in biological
molecules. For example, it is a component of adenosine triphos(ATP) and the coenzyme NADP, which are used in
important cellular
such os photosynthesis. Phosphorus
is also
bClckbone of nucleic
which
amounts of phosphorus are carried by rivers and
to
I~I). Phosphorus exists in
on land. Much of this rUlI"""",,",,'"
Some of the ron,'1<.,,,,,,,,,
The main reservoir of
we will
the cycle with
Erosion occurs
over rock, dissolving phosphorus
into rivers
unites with
streams.
of water,
phosphate
a lake.
In the plale, we see plan!s growing along the
of the
lake. Here, the waler gives up its phosphates, which are
(8) and used in the synthesis of organic
molecules. Some the phosphates also enter the soil along the
margins of the lake. Dissolved phosphate is recJdily absorbed
Ihe roots of plants, concentrated by
and protists
such as Euglena, cmd then
molecules.
u)
c
(I
o
o
o
Erosion from Rock ...... A
Absorbt i on by Pl ants .. B
Concentration in Plant
Tissues ................ C
o
o
o
The Phosphorus Cycle
Plant Consumption ...... 0
Grazing ................ E
Pl ant \>Jaste ............ F
- 311-
o
o
o
o
Animal Waste ............ G
Runoff to Ocean ........ H
Marine Sediment ........ I
Geologic Upthrust ...... J