4.3 Physical V a riables
27
72 UNIT 2 ORGANISMS AND THE ENVIRONMENT Figure 4.11: The biosphere is Earth’s life-supporting layer. ecosystem - a group of living things and their physical surroundings. habitat - a place where an organism lives. 4.3 Physical Variables You have read about the compounds that make up living things. The presence and amount of other compounds like oxygen and water are variables that support life. Living things are found on or near Earth’s surface where the conditions for life are the best. Earth’s life-supporting layer of land, water, and air is known as the biosphere (Figure 4.11). In this section you will learn about the physical (non-living) variables that affect living things in the biosphere. Ecosystems and habitats Living systems As you have learned, an individual organism is made up of many smaller systems that work together. Each system has a structure (its parts) and a function (what it does). This is true for cells, tissues, organs, organ systems, and the entire organism. Ecosystems A higher level of organization of living systems is called an ecosystem. An ecosystem is made up of a group of living things and their physical surroundings. An ecosystem can be as big as the entire biosphere, or as small as a drop of water containing one- celled organisms. The living and nonliving things in an ecosystem function together—kind of like a single organism. Habitats A habitat is a place where a particular type of organism lives. A dolphin’s habitat is the ocean. A goldfish in a fishbowl has a much smaller habitat. There are land habitats, freshwater habitats, and saltwater habitats. Each type of habitat has a set of physical variables such as the amount of sunlight, temperature, and amount of moisture. An organism lives in a habitat where the range of variables is suitable for keeping it alive. For example, a dolphin wouldn’t survive very long in your habitat.
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Transcript of 4.3 Physical V a riables
72U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
4.1
1: T
he
bios
pher
e is
E
arth
’s l
ife-
supp
orti
ng
laye
r.
ecos
yste
m -
a gr
oup
of li
ving
th
ings
and
thei
r phy
sica
l su
rrou
ndin
gs.
habi
tat -
a p
lace
whe
re a
n or
gani
sm li
ves.
4.3
Phys
ical
Var
iabl
es
You
hav
e re
ad a
bou
t th
e co
mpo
un
ds t
hat
mak
e u
p li
vin
g th
ings
. Th
e pr
esen
ce a
nd
amou
nt
of o
ther
com
pou
nds
like
oxy
gen
an
d w
ater
are
var
iabl
es t
hat
su
ppor
t li
fe.
Liv
ing
thin
gs a
re f
oun
d on
or
nea
r E
arth
’s s
urf
ace
wh
ere
the
con
diti
ons
for
life
are
th
e be
st. E
arth
’s li
fe-s
upp
orti
ng
laye
r of
lan
d, w
ater
, an
d ai
r is
kn
own
as
the
bios
pher
e (F
igu
re 4
.11)
. In
th
is s
ecti
on y
ou w
ill l
earn
abo
ut
the
phys
ical
(n
on-l
ivin
g)
vari
able
s th
at a
ffec
t li
vin
g th
ings
in t
he
bios
pher
e.
Ecos
yste
ms
and
habi
tats
Livin
g sy
stem
sA
s yo
u h
ave
lear
ned
, an
indi
vidu
al o
rgan
ism
is m
ade
up
of m
any
smal
ler
syst
ems
that
wor
k to
geth
er. E
ach
sys
tem
has
a s
tru
ctu
re
(its
par
ts)
and
a fu
nct
ion
(w
hat
it d
oes)
. Th
is is
tru
e fo
r ce
lls,
ti
ssu
es, o
rgan
s, o
rgan
sys
tem
s, a
nd
the
enti
re o
rgan
ism
.
Ecos
yste
ms
A h
igh
er le
vel o
f or
gan
izat
ion
of
livi
ng
syst
ems
is c
alle
d an
ec
osys
tem
. An
eco
syst
em is
mad
e u
p of
a g
rou
p of
livi
ng
thin
gs
and
thei
r ph
ysic
al s
urr
oun
din
gs. A
n e
cosy
stem
can
be
as b
ig a
s th
e en
tire
bio
sph
ere,
or
as s
mal
l as
a dr
op o
f w
ater
con
tain
ing
one-
cell
ed o
rgan
ism
s. T
he
livi
ng
and
non
livi
ng
thin
gs in
an
eco
syst
em
fun
ctio
n t
oget
her
—ki
nd
of li
ke a
sin
gle
orga
nis
m.
Habi
tats
A h
abita
t is
a pl
ace
wh
ere
a pa
rtic
ula
r ty
pe o
f or
gan
ism
live
s. A
do
lph
in’s
hab
itat
is t
he
ocea
n. A
gol
dfis
h in
a f
ish
bow
l h
as a
mu
ch s
mal
ler
hab
itat
. Th
ere
are
lan
d h
abit
ats,
fr
esh
wat
er h
abit
ats,
an
d sa
ltw
ater
hab
itat
s. E
ach
typ
e of
hab
itat
has
a s
et o
f ph
ysic
al v
aria
bles
su
ch a
s th
e am
oun
t of
su
nli
ght,
tem
pera
ture
, an
d am
oun
t of
m
oist
ure
. An
org
anis
m li
ves
in a
hab
itat
wh
ere
the
ran
ge o
f va
riab
les
is s
uit
able
for
kee
pin
g it
ali
ve. F
or
exam
ple,
a d
olph
in w
ould
n’t
surv
ive
very
lon
g in
you
r h
abit
at.
734.
3 PH
YSIC
AL
VAR
IAB
LES
CH
APT
ER 4
: PH
YSIC
AL
SCIE
NC
E C
ON
NEC
TIO
NS
Land
hab
itats
Land
varia
bles
Man
y va
riab
les
affe
ct li
fe o
n la
nd.
Fiv
e im
port
ant
ones
are
te
mpe
ratu
re, p
reci
pita
tion
, su
nli
ght,
typ
e of
soi
l, a
nd
oxyg
en.
Tem
pera
ture
Mos
t li
vin
g th
ings
can
su
rviv
e in
tem
pera
ture
s ab
ove
free
zin
g an
d be
low
70°
C. E
xtre
me
tem
pera
ture
s li
mit
th
e n
um
ber
and
kin
ds o
f or
gan
ism
s th
at c
an s
urv
ive.
Tro
pica
l rai
nfo
rest
s h
ave
mod
erat
e te
mpe
ratu
res
and
supp
ort
mor
e sp
ecie
s of
an
imal
s an
d pl
ants
th
an
any
oth
er la
nd
hab
itat
. Pol
ar r
egio
ns
are
very
col
d an
d do
not
su
ppor
t as
man
y sp
ecie
s. T
he
pola
r be
ar is
ada
pted
to
live
in t
he
cold
tem
pera
ture
s of
th
e A
rcti
c (F
igu
re 4
.12)
.
Prec
ipita
tion
Liv
ing
thin
gs n
eed
wat
er t
o su
rviv
e. T
he
amou
nt
of p
reci
pita
tion
(r
ain
or
snow
) de
term
ines
th
e ki
nds
of
livi
ng
thin
gs t
hat
can
su
rviv
e in
a la
nd
hab
itat
. Th
e am
oun
t of
pre
cipi
tati
on o
n E
arth
is
not
eve
nly
dis
trib
ute
d. S
ome
part
s of
Ear
th’s
su
rfac
e ar
e ve
ry d
ry,
wh
ile
oth
ers
are
very
wet
. Th
e m
ap b
elow
sh
ows
the
aver
age
prec
ipit
atio
n t
hat
fal
ls o
n d
iffe
ren
t pa
rts
of E
arth
eac
h y
ear.
Fig
ure
4.1
2: T
he
pola
r be
ar l
ives
in
th
e A
rcti
c. I
t h
as d
ense
fu
r an
d a
th
ick
laye
r of
fat
to
keep
it
war
m.
Des
crib
e yo
ur h
abita
t. W
hat i
s th
e ra
nge
of te
mpe
ratu
res?
How
muc
h pr
ecip
itatio
n do
es it
rece
ive
each
ye
ar?
How
muc
h su
nlig
ht?
Wha
t ty
pe o
f soi
l is
pres
ent?
Wha
t is
your
alti
tude
? Li
st th
e ty
pes
of
orga
nism
s th
at li
ve in
you
r hab
itat.
74U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
4.1
3: F
ern
s ca
n s
urv
ive
wit
h
very
lit
tle
sun
ligh
t. A
cac
tus
nee
ds
a lo
t of
su
nli
ght
to g
row
.
Fig
ure
4.1
4: S
oil
is a
mix
ture
of
dec
ayed
mat
ter
and
roc
k pa
rtic
les.
Sunl
ight
Su
nli
ght
prov
ides
th
e en
ergy
for
livi
ng
thin
gs t
o gr
ow a
nd
surv
ive.
P
lan
ts c
aptu
re t
he
ener
gy fr
om s
un
ligh
t an
d st
ore
it in
th
e fo
rm o
f m
olec
ule
s. A
nim
als
get
thei
r en
ergy
by
eati
ng
plan
ts o
r by
eat
ing
oth
er a
nim
als
that
eat
pla
nts
. Th
e am
oun
t of
su
nli
ght
dete
rmin
es
the
amou
nt
of e
ner
gy a
vail
able
in a
n e
cosy
stem
. Som
e pl
ants
, lik
e fe
rns,
can
su
rviv
e w
ith
ver
y li
ttle
su
nli
ght.
A c
actu
s n
eeds
a lo
t
of s
un
ligh
t to
gro
w (
Fig
ure
4.1
3).
Type
of s
oil
Soi
l is
a m
ixtu
re o
f dec
ayed
pla
nt
and
anim
al p
arts
an
d ve
ry s
mal
l ro
ck p
arti
cles
(F
igu
re 4
.14)
. It
prov
ides
an
an
chor
for
pla
nts
th
at
hav
e ro
ots.
It
also
hol
ds w
ater
an
d n
utr
ien
ts t
o h
elp
plan
ts g
row
. T
he
type
of
soil
var
ies
in d
iffe
ren
t la
nd
hab
itat
s. S
and
doe
s n
ot
hol
d w
ater
ver
y w
ell a
nd
con
tain
s fe
w n
utr
ien
ts. C
lay
has
sm
alle
r pa
rtic
les
than
san
d an
d h
olds
wat
er. T
he
best
soi
ls f
or g
row
ing
plan
ts c
onta
in a
mix
ture
of
part
icle
siz
es a
nd
som
e de
caye
d m
atte
r. S
oil i
s a
hab
itat
for
man
y or
gan
ism
s su
ch a
s ba
cter
ia a
nd
wor
ms.
In
fac
t, a
cu
p of
soi
l con
tain
s bi
llio
ns
of li
vin
g ba
cter
ia!
Oxyg
enM
ost
orga
nis
ms
nee
d ox
ygen
to
live
. Th
e ai
r yo
u b
reat
he
is a
bou
t 21
% o
xyge
n. T
he
amou
nt
of o
xyge
n in
th
e ai
r va
ries
dep
endi
ng
on
alti
tude
. Hab
itat
s at
hig
her
alt
itu
des,
like
mou
nta
in t
ops,
hav
e le
ss o
xyge
n t
han
hab
itat
s at
low
er a
ltit
ude
s. P
eopl
e w
ho
live
at
hig
h a
ltit
ude
s h
ave
adap
ted
to b
reat
hin
g le
ss o
xyge
n. I
f you
live
at
a lo
w a
ltit
ude
an
d vi
sit
a h
igh
er a
ltit
ude
, you
may
not
ice
that
you
ar
e sh
ort
of b
reat
h. I
f yo
u s
pen
d en
ough
tim
e th
ere
thou
gh, y
our
body
wil
l ada
pt.
Air h
abita
ts
Som
e or
gan
ism
s sp
end
mu
ch o
f th
eir
tim
e in
th
e ai
r. H
owev
er,
mos
t oc
casi
onal
ly r
etu
rn t
o la
nd.
Org
anis
ms
that
spe
nd
tim
e in
th
e ai
r ar
e af
fect
ed b
y th
e sa
me
vari
able
s as
th
ose
that
live
on
la
nd.
Can
you
nam
e so
me
orga
nis
ms
that
spe
nd
mu
ch o
f th
eir
tim
e in
th
e ai
r?
754.
3 PH
YSIC
AL
VAR
IAB
LES
CH
APT
ER 4
: PH
YSIC
AL
SCIE
NC
E C
ON
NEC
TIO
NS
Fres
hwat
er h
abita
tsDi
strib
utio
n of
wa
ter o
n Ea
rthW
ater
cov
ers
71%
of E
arth
’s s
urf
ace.
Th
e oc
ean
s co
nta
in ju
st a
bou
t al
l of
the
wat
er a
vail
able
to
livi
ng
thin
gs. O
nly
a s
mal
l fra
ctio
n o
f E
arth
’s w
ater
is f
oun
d in
fre
shw
ater
hab
itat
s su
ch a
s ri
vers
, st
ream
s, la
kes,
an
d po
nds
(F
igu
re 4
.15)
.
Varia
bles
in
fresh
wate
rha
bita
ts
Var
iabl
es t
hat
aff
ect
life
on
lan
d al
so a
ffec
t li
fe in
fre
sh w
ater
. T
hes
e in
clu
de t
empe
ratu
re, p
reci
pita
tion
, su
nli
ght,
typ
e of
soi
l on
su
rrou
ndi
ng
lan
d, a
nd
oxyg
en. T
he
chem
ical
con
ten
t of
th
e w
ater
is
very
impo
rtan
t in
det
erm
inin
g w
hic
h t
ypes
of l
ife
can
su
rviv
e th
ere.
pHpH
is a
mea
sure
of
chem
ical
s ca
lled
aci
ds
and
base
s in
wat
er. p
H
ran
ges
from
0 t
o 14
. Pu
re w
ater
is p
H 7
(neu
tral
). L
ower
pH
val
ues
in
dica
te t
he
pres
ence
of
acid
s. M
ost
aqu
atic
pla
nts
an
d an
imal
s fu
nct
ion
bes
t w
hen
pH
is b
etw
een
6 a
nd
8. M
ost
fish
hav
e tr
oubl
e re
prod
uci
ng
wh
en t
he
pH is
too
aci
dic
(Fig
ure
4.1
6).
Diss
olve
dox
ygen
Th
e ox
ygen
ava
ilab
le t
o li
vin
g th
ings
in w
ater
is c
alle
d d
isso
lved
ox
ygen
. Fis
h “
brea
the”
by
pass
ing
wat
er o
ver
thei
r gi
lls
to e
xtra
ct
the
diss
olve
d ox
ygen
. A g
ood
amou
nt
of d
isso
lved
oxy
gen
for
mos
t aq
uat
ic li
fe is
abo
ut
9 pa
rts
per
mil
lion
. Th
e am
oun
t of
dis
solv
ed
oxyg
en in
fre
shw
ater
var
ies
wit
h t
empe
ratu
re a
nd
mov
emen
t.
Coo
ler
wat
ers
hol
d m
ore
oxyg
en t
han
war
mer
wat
ers.
Fas
t-m
ovin
g st
ream
s co
nta
in m
ore
oxyg
en t
han
sta
ndi
ng
wat
ers
like
pon
ds.
Nitra
tes a
nd
phos
phat
esN
itra
tes
and
phos
phat
es a
re im
port
ant
nu
trie
nts
for
livi
ng
thin
gs.
Th
ey a
re o
ften
use
d as
fer
tili
zers
for
lan
d cr
ops.
Ru
nof
f fr
om r
ain
w
ash
es t
hes
e ch
emic
als
into
bod
ies
of w
ater
. Too
man
y n
itra
tes
and
phos
phat
es c
ause
larg
e gr
owth
s of
wat
er p
lan
ts. A
s th
e w
ater
pl
ants
die
, th
ey a
re e
aten
by
bact
eria
in t
he
wat
er t
hat
use
di
ssol
ved
oxyg
en. T
his
pro
cess
low
ers
the
amou
nt
of d
isso
lved
ox
ygen
ava
ilab
le t
o ot
her
org
anis
ms.
Fig
ure
4.1
5: T
he
dis
trib
uti
on o
f E
arth
’s w
ater
.
Fig
ure
4.1
6: M
ost
fish
can
su
rviv
e w
ith
in t
he
6 to
8 p
H r
ange
.
76U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
4.1
7: T
he
mai
n c
hem
ical
s d
isso
lved
in
oce
an w
ater
.
Fig
ure
4.1
8: T
hes
e d
eep-
sea
fish
can
pr
odu
ce t
hei
r ow
n l
igh
t.
Ch
emic
al
Co
nce
ntr
ati
on
(p
pt)
chlo
ride
19.3
sodi
um
10.8
sulf
ate
2.7
mag
nes
ium
1.3
calc
ium
0.4
pota
ssiu
m0.
4
bica
rbon
ate
0.1
The
ocea
nsCh
emica
ls in
oc
ean
wate
rT
he
salt
y oc
ean
s ar
e th
e m
ost
stab
le o
f E
arth
’s h
abit
ats.
Th
e sa
lt
con
ten
t of
th
e oc
ean
s h
as r
emai
ned
sta
ble
for
600
mil
lion
yea
rs!
Th
e ch
emic
als
that
th
e di
ssol
ved
salt
s ar
e m
ade
of in
clu
de s
odiu
m,
chlo
ride
, su
lfat
e, m
agn
esiu
m, c
alci
um
, an
d po
tass
ium
(F
igu
re 4
.17)
. Th
e co
nce
ntr
atio
n o
f sa
lts
in t
he
ocea
n is
35
part
s pe
r th
ousa
nd
(ppt
). T
his
mea
ns
that
th
ere
are
35 g
ram
s of
sal
ts
diss
olve
d in
eve
ry li
ter
of s
eaw
ater
.
Ocea
ns ar
e di
vided
into
zo
nes
Sci
enti
sts
divi
de t
he
ocea
n in
to la
yers
cal
led
zon
es. Z
ones
ext
end
from
th
e su
rfac
e to
th
e bo
ttom
of
the
deep
est
tren
ches
. As
you
go
deep
er, t
empe
ratu
re a
nd
ligh
t de
crea
se, a
nd
pres
sure
incr
ease
s.
Life
in th
e zon
esM
ost
life
in t
he
ocea
ns
is c
once
ntr
ated
in z
ones
wh
ere
ligh
t ca
n
pen
etra
te. I
n m
ost
plac
es, l
igh
t do
es n
ot r
each
dee
per
than
200
m
eter
s. P
lan
ts t
hat
use
su
nli
ght
to m
ake
food
can
not
live
bey
ond
this
dep
th. L
ife
is d
iffi
cult
for
org
anis
ms
in t
he
deep
zon
es. T
hey
m
ust
ove
rcom
e la
ck o
f lig
ht,
low
tem
pera
ture
s, a
nd
extr
emel
y h
igh
pr
essu
res.
Som
e or
gan
ism
s ar
e ab
le t
o pr
odu
ce t
hei
r ow
n li
ght
so t
hey
can
fin
d fo
od a
nd
loca
te o
ther
s of
th
eir
sam
e sp
ecie
s (F
igu
re 4
.18)
.
774.
3 PH
YSIC
AL
VAR
IAB
LES
CH
APT
ER 4
: PH
YSIC
AL
SCIE
NC
E C
ON
NEC
TIO
NS
4.3
Sect
ion
Rev
iew
1.E
xpla
in t
he
diff
eren
ce b
etw
een
an
eco
syst
em a
nd
a h
abit
at.
Giv
e tw
o ex
ampl
es o
f ea
ch.
2.D
escr
ibe
the
hab
itat
of
the
orga
nis
m in
Fig
ure
4.1
9. L
ist
thre
e ph
ysic
al v
aria
bles
of
the
hab
itat
.3.
Lis
t an
d de
scri
be t
he
phys
ical
var
iabl
es o
f la
nd
hab
itat
s.4.
San
d is
a t
ype
of s
oil b
est
desc
ribe
d as
:a.
mos
tly
deca
yed
mat
ter
wit
h t
iny
rock
par
ticl
es.
b.la
rge
rock
par
ticl
es a
nd
very
litt
le d
ecay
ed m
atte
r.c.
very
sm
all r
ock
part
icle
s th
at h
old
wat
er w
ell.
d.fo
un
d on
ly o
n b
each
es.
5.C
arlo
s w
ants
to
set
up
a fr
esh
wat
er f
ish
tan
k.a.
Lis
t th
e va
riab
les
he
shou
ld c
onsi
der
wh
en s
etti
ng
up
his
ta
nk.
b.E
xpla
in h
ow C
arlo
s co
uld
kee
p a
good
leve
l of
diss
olve
d ox
ygen
in h
is t
ank.
c.W
hy
shou
ld C
arlo
s te
st f
or p
H?
6.H
atch
etfi
sh li
ve in
ver
y de
ep p
arts
of
the
ocea
n. W
hat
ch
alle
nge
s m
ust
th
ey o
verc
ome
to s
urv
ive
in t
his
en
viro
nm
ent?
Fig
ure
4.1
9: U
se t
his
pic
ture
to
answ
er q
ues
tion
2.
Cer
tain
pop
ulat
ions
hav
e sp
ecifi
c na
mes
like
a h
erd
of c
ows
or a
pr
ide
of li
ons.
The
se te
rms
are
refe
rred
to a
s co
llect
ive
noun
s.
Writ
e a
shor
t sto
ry a
bout
po
pula
tions
of o
rgan
ism
s. Y
our
stor
y sh
ould
incl
ude
at le
ast f
ive
diffe
rent
col
lect
ive
noun
s.
Cha
pter
5
Ecos
yste
ms
A s
ea o
tter
wak
es u
p fr
om a
nap
an
d u
nw
raps
itse
lf f
rom
th
e la
rge
fron
d of
kel
p th
at w
as k
eepi
ng
it f
rom
flo
atin
g aw
ay
wh
ile
slee
pin
g. T
he
play
ful s
ea o
tter
div
es t
o th
e oc
ean
flo
or,
look
ing
for
tast
y se
a u
rch
ins
that
are
fee
din
g on
th
e ke
lp.
Aft
er b
rin
gin
g a
sea
urc
hin
to
the
surf
ace,
th
e se
a ot
ter
floa
ts
on it
s ba
ck in
th
e su
nsh
ine,
ope
ns
the
urc
hin
by
ban
gin
g on
it
wit
h a
roc
k, a
nd
eats
it. T
he
ocea
n w
ater
, kel
p, s
ea u
rch
ins,
se
a ot
ter,
su
nsh
ine—
inde
ed, a
ll o
f th
e li
vin
g an
d n
onli
vin
g th
ings
th
at in
tera
ct in
th
is c
oast
al m
arin
e ar
ea—
mak
e u
p an
ec
osys
tem
. Wh
at t
ypes
of
ecos
yste
ms
are
fou
nd
wh
ere
you
li
ve?
1.W
hat i
s an
ecos
yste
m?
2.W
hat i
s a c
omm
on w
ay to
show
“wh
o ea
ts wh
om”
in a
n ec
osys
tem
?3.
Why
are
eco
syste
ms i
n a
“del
icat
e ba
lanc
e”?
84U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Res
earc
h, li
st, a
nd d
escr
ibe
at
leas
t tw
o po
pula
tions
that
mak
e up
ea
ch o
f the
four
trop
ical
rain
fore
st
com
mun
ities
.
5.1
Ecos
yste
ms,
Ene
rgy,
and
Nut
rient
s
Did
an
yon
e ev
er a
sk y
ou t
he
ques
tion
: “W
her
e do
you
get
you
r en
ergy
?” E
ner
gy
ente
rs o
ur
wor
ld f
rom
th
e S
un
—bu
t h
ow d
oes
the
Su
n’s
en
ergy
bec
ome
you
r en
ergy
? R
ead
this
sec
tion
to
fin
d ou
t.
Hig
her l
evel
s of
org
aniz
atio
nOr
gani
zing
livin
g th
ings
You
hav
e le
arn
ed h
ow a
n in
divi
dual
livi
ng
thin
g is
org
aniz
ed in
to
cell
s, t
issu
es, o
rgan
s, a
nd
orga
n s
yste
ms.
In
divi
dual
org
anis
ms
can
be
grou
ped
into
hig
her
leve
ls o
f or
gan
izat
ion
. Org
anis
ms
of
the
sam
e sp
ecie
s ar
e gr
oupe
d in
to p
opu
lati
ons.
Pop
ula
tion
s of
di
ffer
ent
spec
ies
of o
rgan
ism
s ar
e gr
oupe
d in
to c
omm
un
itie
s.
Dif
fere
nt
com
mu
nit
ies
form
eco
syst
ems,
wh
ich
mak
e u
p th
e bi
osph
ere.
An ex
ampl
e of a
n ec
osys
tem
A t
ropi
cal r
ain
fore
st is
an
exa
mpl
e of
an
eco
syst
em. Y
ou h
ave
read
th
at a
n e
cosy
stem
is m
ade
up
of a
gro
up
of li
vin
g th
ings
an
d th
eir
phys
ical
su
rrou
ndi
ngs
. A t
ropi
cal r
ain
fore
st e
cosy
stem
is m
ade
up
of t
he
plan
ts a
nd
anim
als
that
live
th
ere,
plu
s n
onli
vin
g th
ings
li
ke s
oil,
air,
wat
er, s
un
ligh
t, a
nd
nu
trie
nts
. Th
e li
vin
g an
d n
onli
vin
g pa
rts
of a
n e
cosy
stem
wor
k to
geth
er li
ke a
tea
m.
855.
1 EC
OSY
STEM
S, E
NER
GY,
AN
D N
UTR
IEN
TS
CH
APT
ER 5
: EC
OSY
STEM
S
Pho
tosy
nthe
sis
and
ener
gySu
nlig
htS
un
ligh
t is
alm
ost
alw
ays
the
firs
t ty
pe o
f en
ergy
to
ente
r an
ec
osys
tem
. How
is e
ner
gy f
rom
th
e S
un
use
ful t
o an
eco
syst
em?
You
may
alr
eady
kn
ow t
hat
som
e li
vin
g th
ings
, lik
e pl
ants
, are
abl
e to
cap
ture
th
e en
ergy
fro
m s
un
ligh
t (F
igu
re 5
.1).
Wh
en a
not
her
li
vin
g th
ing
in a
n e
cosy
stem
eat
s a
plan
t, it
is g
ain
ing
ener
gy t
hat
ca
me
firs
t fr
om t
he
Su
n.
Phot
osyn
thes
isP
hot
osyn
thes
is h
appe
ns
wh
en a
pla
nt
use
s th
e S
un
’s e
ner
gy t
o co
nve
rt w
ater
an
d ca
rbon
dio
xide
into
car
boh
ydra
tes
such
as
suga
rs a
nd
star
ches
. Car
boh
ydra
tes
are
mol
ecu
les
that
sto
re
ener
gy in
th
e fo
rm o
f ch
emic
al b
onds
. A c
ompa
ny
that
bot
tles
or
ange
juic
e on
ce a
dver
tise
d th
at t
her
e is
a li
ttle
su
nsh
ine
in e
very
bo
ttle
. Th
ere
is s
ome
scie
nti
fic
tru
th t
o th
at a
dver
tise
men
t!
Fig
ure
5.1
: Th
e le
aves
of
a pl
ant
are
orga
ns
that
col
lect
lig
ht
for
phot
osyn
thes
is.
86U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
5.2
: Mu
shro
oms
are
fun
gi
that
hel
p d
ecom
pose
fal
len
bra
nch
es
and
lea
ves
on t
he
fore
st f
loor
.
prod
ucer
- a
livin
g th
ing
that
can
m
ake
its o
wn
food
.
cons
umer
- a
livin
g th
ing
that
ea
ts o
ther
livi
ng th
ings
for f
ood
and
ener
gy.
herb
ivor
e - a
con
sum
er th
at e
ats
only
pla
nts.
carn
ivor
e - a
con
sum
er th
at e
ats
only
ani
mal
s.
omni
vore
- a
cons
umer
that
eat
s bo
th p
lant
s an
d an
imal
s.
deco
mpo
ser -
a li
ving
thin
g th
at
brea
ks d
own
was
te a
nd d
ead
thin
gs.
Prod
ucer
s, c
onsu
mer
s, a
nd d
ecom
pose
rsPr
oduc
ers
Mos
t ec
osys
tem
s ge
t th
eir
ener
gy f
irst
fro
m s
un
ligh
t. A
pro
duce
r is
a li
vin
g th
ing,
like
a p
lan
t, t
hat
can
mak
e it
s ow
n f
ood.
An
oth
er
wor
d fo
r “p
rodu
ce”
is m
ake.
Pla
nts
use
th
e S
un
’s e
ner
gy t
o m
ake
thei
r ow
n f
ood.
Tre
es a
re c
omm
on p
rodu
cers
in a
tro
pica
l ra
info
rest
eco
syst
em.
Cons
umer
sO
ther
mem
bers
of
ecos
yste
ms
can
not
mak
e th
eir
own
foo
d. A
co
nsum
er m
ust
feed
on
oth
er li
vin
g th
ings
to
get
food
an
d en
ergy
. A
not
her
wor
d fo
r “c
onsu
me”
is e
at. C
onsu
mer
s ea
t ot
her
livi
ng
thin
gs. A
her
bivo
re is
a c
onsu
mer
th
at e
ats
only
pla
nts
. A
carn
ivor
e is
a c
onsu
mer
th
at e
ats
only
an
imal
s. A
con
sum
er t
hat
ea
ts b
oth
pla
nts
an
d an
imal
s is
cal
led
an o
mni
vore
. Th
ere
are
man
y co
nsu
mer
s in
a t
ropi
cal r
ain
fore
st e
cosy
stem
. In
sect
s,
cate
rpil
lars
, an
d m
onke
ys f
eed
on t
he
plan
ts a
nd
tree
s. T
hes
e h
erbi
vore
s ar
e ea
ten
by
carn
ivor
es s
uch
as
pum
as. W
hat
abo
ut
you
? A
re y
ou a
her
bivo
re, c
arn
ivor
e, o
r an
om
niv
ore?
Deco
mpo
sers
All
livi
ng
thin
gs in
an
eco
syst
em c
reat
e w
aste
an
d ev
entu
ally
die
. If
was
te a
nd
dead
org
anis
ms
are
not
som
ehow
bro
ken
dow
n, t
he
com
pou
nds
th
ey c
onta
in w
ould
not
bec
ome
avai
labl
e fo
r ot
her
li
vin
g or
gan
ism
s in
th
at e
cosy
stem
. Th
e w
aste
wou
ld p
ile
up
and
pote
nti
ally
har
m li
vin
g th
ings
. Im
agin
e w
hat
it w
ould
be
like
in
you
r n
eigh
borh
ood
if t
he
tras
h w
as n
ot t
aken
aw
ay—
you
wou
ld
not
be
able
to
stay
th
ere
for
very
lon
g w
ith
out
gett
ing
sick
. A
deco
mpo
ser i
s a
livi
ng
thin
g th
at c
onsu
mes
was
te a
nd
dead
or
gan
ism
s to
get
en
ergy
. “D
ecom
pose
” m
ean
s to
bre
ak d
own
. D
ecom
pose
rs b
reak
dow
n m
ater
ial f
rom
was
te a
nd
dead
or
gan
ism
s, a
nd
the
com
pou
nds
are
ret
urn
ed t
o th
e ec
osys
tem
. F
un
gi a
nd
bact
eria
are
dec
ompo
sers
in m
any
ecos
yste
ms
(Fig
ure
5.2
). D
ecom
pose
rs a
re im
port
ant
and
can
be
call
ed
nat
ure
’s r
ecyc
lers
.
875.
1 EC
OSY
STEM
S, E
NER
GY,
AN
D N
UTR
IEN
TS
CH
APT
ER 5
: EC
OSY
STEM
S
Ener
gy fl
ow a
nd n
utrie
nt c
ycle
sTh
e flo
w of
en
ergy
En
ergy
flo
ws
from
pro
duce
rs t
o co
nsu
mer
s an
d ev
entu
ally
to
deco
mpo
sers
in a
n e
cosy
stem
. For
exa
mpl
e, w
hen
a m
ouse
eat
s se
eds,
en
ergy
sto
red
in t
he
seed
s fl
ows
to t
he
mou
se. W
hen
a
haw
k ea
ts t
he
mou
se, e
ner
gy f
low
s fr
om t
he
mou
se t
o th
e h
awk.
Th
e en
ergy
left
in w
aste
s an
d de
ad o
rgan
ism
s fl
ows
to
the
deco
mpo
sers
. At
each
ste
p, s
ome
of t
hat
en
ergy
is lo
st in
th
e fo
rm o
f u
nu
sabl
e h
eat.
Th
is m
ean
s th
at e
ner
gy is
co
nti
nu
ousl
y lo
st t
o th
e ec
osys
tem
. You
wil
l rea
d m
ore
abou
t en
ergy
an
d ec
osys
tem
s in
th
e n
ext
sect
ion
.
Nutri
ents
are
cycle
d th
roug
h th
e eco
syst
em
Th
e en
ergy
ava
ilab
le t
o th
e ec
osys
tem
is c
onti
nu
ousl
y lo
st
as u
nu
sabl
e h
eat
as it
mov
es f
rom
on
e m
embe
r to
an
oth
er. N
utr
ien
ts a
re d
iffe
ren
t. N
utr
ien
ts a
re t
he
elem
ents
an
d co
mpo
un
ds n
eede
d by
org
anis
ms
to
stay
ali
ve. N
utr
ien
ts li
ke w
ater
, car
bon
, oxy
gen
, n
itro
gen
, an
d ca
lciu
m, a
re c
ycle
d th
rou
gh t
he
ecos
yste
m a
nd
con
tin
uou
sly
reu
sed.
Th
at’s
wh
y,
wh
en s
cien
tist
s ta
lk a
bou
t th
e w
ater
or
carb
on in
a
ecos
yste
m, t
hey
use
ter
ms
like
“w
ater
cyc
le”
or
“car
bon
-oxy
gen
cyc
le.”
The i
mpo
rtanc
e of
dec
ompo
sers
Dec
ompo
sers
pla
y im
port
ant
role
s in
nu
trie
nt
cycl
es. D
ecom
pose
rs li
ke f
un
gi a
nd
bact
eria
re
turn
nu
trie
nts
to
the
soil
, wat
er, o
r ai
r,
wh
ere
they
can
aga
in b
e u
sed
by t
he
oth
er li
vin
g m
embe
rs o
f th
e ec
osys
tem
. Th
e di
agra
m (
righ
t)
show
s h
ow li
vin
g th
ings
are
lin
ked
toge
ther
by
ener
gy a
nd
nu
trie
nts
in e
cosy
stem
s.
88U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Und
erst
andi
ng a
cyc
le d
iagr
amR
efer
to th
e w
ater
cyc
le d
iagr
am
on th
is p
age
to p
ract
ice
this
stu
dy
skill.
1. P
lace
you
r fin
ger o
n a
part
of th
e cy
cle.
A c
ycle
repe
ats
over
and
ov
er, s
o it
does
not
mat
ter w
here
yo
u be
gin.
2. F
ollo
w th
e ar
row
s in
the
diag
ram
w
hile
trac
ing
your
fing
er a
long
the
path
way
.
3. R
ead
each
labe
l and
mak
e su
re
you
unde
rsta
nd w
hat h
appe
ns
durin
g ea
ch s
tep.
4. R
efer
to th
e di
agra
m a
nd w
rite
dow
n a
few
sen
tenc
es a
bout
wha
t ha
ppen
s in
the
cycl
e fro
m s
tart
to
finis
h.
The
wat
er a
nd c
arbo
n-ox
ygen
cyc
les
Wat
er an
d su
nlig
htL
ivin
g th
ings
nee
d w
ater
an
d su
nli
ght.
Th
e S
un
is a
lway
s th
ere,
bu
t w
hat
abo
ut
wat
er?
Wat
er s
upp
ly d
epen
ds o
n t
he
wat
er c
ycle
. Nat
ure
all
ows
wat
er
to r
ecyc
le s
o it
can
be
use
d in
m
any
ecos
yste
ms.
Loo
k at
th
e pi
ctu
re t
o th
e le
ft. W
her
e do
es
the
ener
gy c
ome
from
to
mak
e th
e w
ater
cyc
le w
ork?
Th
at’s
ri
ght,
th
e S
un
is t
he
sou
rce
of
ener
gy.
Carb
on an
d ox
ygen
Eve
n t
hou
gh w
e ca
n’t
see
them
, ca
rbon
an
d ox
ygen
are
impo
rtan
t pa
rts
of e
cosy
stem
s. T
he
carb
on-
oxyg
en c
ycle
des
crib
es h
ow t
he
ecos
yste
m u
ses
thes
e im
port
ant
elem
ents
. Car
bon
is p
rese
nt
in
both
air
an
d w
ater
as
carb
on
diox
ide
gas.
Oxy
gen
is a
lso
a ga
s th
at is
fou
nd
in a
ir a
nd
wat
er.
Pro
duce
rs t
ake
in c
arbo
n d
ioxi
de
duri
ng
the
proc
ess
of
phot
osyn
thes
is, a
nd
rele
ase
oxyg
en. C
onsu
mer
s ta
ke in
oxy
gen
for
th
eir
life
pro
cess
es a
nd
rele
ase
carb
on d
ioxi
de. W
hen
you
bre
ath
e in
, you
r bo
dy g
ets
the
oxyg
en it
nee
ds. W
hen
you
bre
ath
e ou
t, y
our
body
get
s ri
d of
ca
rbon
dio
xide
. Th
is c
arbo
n d
ioxi
de is
nee
ded
by p
rodu
cers
in y
our
ecos
yste
m.
895.
1 EC
OSY
STEM
S, E
NER
GY,
AN
D N
UTR
IEN
TS
CH
APT
ER 5
: EC
OSY
STEM
S
5.1
Sect
ion
Rev
iew
1.W
hat
is a
n e
cosy
stem
? 2.
Use
th
e te
rms
prod
uce
r, c
onsu
mer
, an
d d
ecom
pose
r to
labe
l eac
h
mem
ber
of t
he
mea
dow
eco
syst
em: g
rass
, gra
ssh
oppe
r, f
rog,
sn
ake,
haw
k, a
nd
fun
gus.
3.W
hat
pro
cess
ch
ange
s li
ght
ener
gy in
to c
hem
ical
en
ergy
(en
ergy
th
at c
an b
e u
sed
by o
rgan
ism
s ot
her
th
an p
rodu
cers
) in
an
ec
osys
tem
?4.
How
are
nu
trie
nts
cyc
led
back
into
th
e ec
osys
tem
fro
m w
hic
h
they
cam
e?5.
A _
____
____
____
____
____
is t
he
type
of o
rgan
ism
th
at u
nde
rgoe
s ph
otos
ynth
esis
, con
vert
ing
ener
gy in
to a
usa
ble
form
of
food
for
ot
her
org
anis
ms
in a
n e
cosy
stem
. 6.
Wh
at f
orm
of
ener
gy is
lost
by
mov
ing
from
pro
duce
r to
co
nsu
mer
to
deco
mpo
ser
in a
n e
cosy
stem
?a.
ligh
tb.
hea
tc.
food
en
ergy
7.R
esea
rch
th
e te
rm c
hem
osyn
thes
is o
n t
he
Inte
rnet
. Aft
er
rese
arch
ing
the
term
, exp
lain
wh
at c
hem
osyn
thes
is is
. Th
en
prov
ide
an e
xpla
nat
ion
for
wh
y th
e st
atem
ent,
“al
l liv
ing
thin
gs
requ
ire
ener
gy f
rom
th
e S
un
” is
not
tru
e.8.
BO
NU
S Q
UE
ST
ION
: Wh
at is
th
e n
ame
of t
he
cact
us
pict
ure
d to
th
e ri
ght?
The
Son
oran
Des
ert c
over
s ab
out
120,
000
squa
re m
iles
in
sout
hwes
tern
Ariz
ona,
so
uthe
aste
rn C
alifo
rnia
, and
par
ts
of M
exic
o. D
ivid
e yo
ur jo
urna
l pa
ge in
to tw
o co
lum
ns la
bele
d P
rodu
cers
and
Con
sum
ers.
Do
som
e re
sear
ch a
nd li
st fi
ve
diffe
rent
com
mon
pro
duce
rs a
nd
cons
umer
s in
the
Son
oran
Des
ert.
90U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
5.3
: How
wou
ld t
hes
e m
embe
rs o
f a
mea
dow
eco
syst
em b
e li
nke
d i
n a
foo
d c
hai
n?
food
cha
in -
show
s ho
w e
ach
mem
ber o
f an
ecos
yste
m
com
mun
ity g
ets
its fo
od.
5.2
Food
Cha
ins
and
Food
Web
s
All
livi
ng
thin
gs n
eed
ener
gy. T
hey
get
en
ergy
fro
m f
ood.
For
exa
mpl
e, a
n o
cean
pl
ant
call
ed k
elp
is e
aten
by
sea
urc
hin
s. S
ea o
tter
s ea
t th
e se
a u
rch
ins.
In
tu
rn, a
se
a ot
ter
mig
ht
be e
aten
by
a sh
ark.
In
eac
h c
ase,
en
ergy
is t
ran
sfer
red
from
th
e or
gan
ism
th
at is
eat
en t
o th
e or
gan
ism
th
at e
ats
it.
Wha
t is
a fo
od c
hain
?A
simpl
e fo
od ch
ainA
food
cha
in s
how
s h
ow e
ach
mem
ber
of a
n e
cosy
stem
get
s it
s fo
od. A
sim
ple
food
ch
ain
lin
ks a
pro
duce
r, a
n h
erbi
vore
, an
d on
e or
mor
e ca
rniv
ores
(F
igu
re 5
.3).
Arr
ows
in t
he
food
ch
ain
sh
ow
how
en
ergy
is p
asse
d fr
om o
ne
lin
k to
an
oth
er.
Prod
ucer
s are
pl
entif
ulW
hat
is t
he
mos
t pl
enti
ful m
embe
r of
a fi
eld
ecos
yste
m?
You
mig
ht
answ
er “
carn
ivor
es,”
sin
ce t
her
e ar
e th
ree
exam
ples
of
carn
ivor
es
in t
he
illu
stra
tion
abo
ve. H
owev
er, g
rass
es a
nd
oth
er p
rodu
cers
ar
e m
uch
mor
e pl
enti
ful t
han
car
niv
ores
. Th
is f
ood
chai
n s
how
s h
ow e
ach
mem
ber
of t
he
ecos
yste
m g
ets
its
food
. It
is n
ot m
ean
t to
sh
ow h
ow m
any
of e
ach
typ
e of
org
anis
m t
her
e is
in t
he
ecos
yste
m.
915.
2 FO
OD
CH
AIN
SA
ND
FO
OD
WEB
S
CH
APT
ER 5
: EC
OSY
STEM
S
Ener
gy a
nd fo
od c
hain
sEn
ergy
de
crea
ses a
s you
m
ove u
p in
a fo
od
chain
Th
ere
are
mor
e pr
odu
cers
th
an h
erbi
vore
s or
car
niv
ores
in a
n
ecos
yste
m. W
hen
an
her
bivo
re e
ats
a pl
ant,
on
ly s
ome
of t
he
plan
t’s
ener
gy b
ecom
es p
art
of t
he
her
bivo
re’s
bod
y. T
he
rest
is lo
st a
s w
aste
or
hea
t. A
lso,
wh
en a
car
niv
ore
eats
an
oth
er a
nim
al, o
nly
so
me
of t
hat
en
ergy
bec
omes
par
t of
th
e ca
rniv
ore’
s bo
dy. T
he
amou
nt
of e
ner
gy t
hat
get
s pa
ssed
alo
ng
from
th
e or
igin
al p
rodu
cer
beco
mes
less
an
d le
ss a
s yo
u m
ove
up
a fo
od c
hai
n.
Ener
gy p
yram
idA
n e
nerg
y py
ram
id is
a g
ood
way
to
show
how
en
ergy
mov
es f
rom
on
e fe
edin
g le
vel t
o th
e n
ext
in a
foo
d ch
ain
. Wh
y is
th
e py
ram
id a
go
od s
hap
e fo
r th
e di
agra
m?
Bec
ause
a p
yram
id is
wid
e at
th
e ba
se
and
nar
row
at
the
top.
As
you
mov
e u
p th
e py
ram
id f
rom
pro
duce
r to
con
sum
er, t
he
diag
ram
get
s sm
alle
r an
d sm
alle
r to
sh
ow h
ow
less
an
d le
ss e
ner
gy is
ava
ilab
le.
1 en
ergy
uni
t
10 e
nerg
y un
its
100
ener
gy u
nits
1,00
0 en
ergy
uni
ts
10,0
00 e
nerg
y un
its
An
ener
gy p
yram
id s
how
s ho
w m
any
units
of e
nerg
yth
ere
are
at e
ach
leve
l of a
food
cha
in.
ener
gy p
yram
id -
diag
ram
that
sh
ows
how
ene
rgy
mov
es fr
om
one
feed
ing
leve
l to
the
next
in a
fo
od c
hain
.
Ther
e ca
nnot
be
too
man
y lin
ks in
an
y fo
od c
hain
bec
ause
the
anim
als
at th
e to
p of
the
ener
gy
pyra
mid
wou
ld n
ot g
et e
noug
h en
ergy
to s
tay
aliv
e.
1.D
escr
ibe
a pa
ttern
that
you
se
e in
the
pyra
mid
’s e
nerg
y un
it nu
mbe
rs.
2.H
ow m
any
times
mor
e en
ergy
un
its d
oes
the
gras
s ha
ve th
an
the
gras
shop
per?
3.H
ow m
any
times
mor
e en
ergy
un
its d
oes
the
frog
have
than
th
e sn
ake?
92U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
food
web
- a
grou
p of
ov
erla
ppin
g fo
od c
hain
s in
an
ecos
yste
m.
The
food
web
mem
bers
pic
ture
d on
this
pag
e ar
e: s
eaw
eed,
wor
m,
zoop
lank
ton
(tiny
floa
ting
anim
als
that
eat
pro
duce
rs),
snai
l, cr
ab,
sard
ine
(sm
all f
ish)
, stri
ped
bass
(la
rge
fish)
, sea
l, an
d gu
ll. M
ake
a sk
etch
of e
ach
sim
ple
food
cha
in
that
mak
es u
p th
e w
eb, a
nd la
bel
each
mem
ber w
ith it
s co
mm
on
nam
e.
Food
web
sW
hat i
s a fo
od
web?
Mos
t an
imal
s ar
e pa
rt o
f mor
e th
an o
ne
food
ch
ain
. Th
ey e
at m
ore
than
on
e ki
nd
of fo
od t
o ge
t en
ough
en
ergy
an
d n
utr
ien
ts. Y
ou c
an
con
nec
t m
any
food
ch
ain
s to
for
m a
food
web
. How
man
y si
mpl
e fo
od c
hai
ns
are
show
n in
th
e fo
od w
eb b
elow
?
935.
2 FO
OD
CH
AIN
SA
ND
FO
OD
WEB
S
CH
APT
ER 5
: EC
OSY
STEM
S
5.2
Sect
ion
Rev
iew
1.H
ow is
a f
ood
web
dif
fere
nt
from
a f
ood
chai
n?
2.C
ircl
e al
l of
the
term
s th
at a
pply
to
the
orga
nis
ms
in F
igu
re 5
.4:
a.F
ield
mou
se: c
onsu
mer
, om
niv
ore,
her
bivo
re, c
arn
ivor
e,
prod
uce
r, p
hot
osyn
thes
izer
, pla
nt,
an
imal
b.R
ed fo
x: c
onsu
mer
, om
niv
ore,
her
bivo
re, c
arn
ivor
e, p
rodu
cer,
ph
otos
ynth
esiz
er, p
lan
t, a
nim
alc.
Gre
en p
lan
t: c
onsu
mer
, om
niv
ore,
her
bivo
re, c
arn
ivor
e,
prod
uce
r, p
hot
osyn
thes
izer
, pla
nt,
an
imal
d.S
nak
e: c
onsu
mer
, om
niv
ore,
her
bivo
re, c
arn
ivor
e, p
rodu
cer,
ph
otos
ynth
esiz
er, p
lan
t, a
nim
al3.
Ske
tch
th
e co
rrec
t fo
od c
hai
n f
or t
he
orga
nis
ms
pict
ure
d in
F
igu
re 5
.4. (
Hin
t: f
oxes
are
kn
own
to
eat
rept
iles
!)4.
Nam
e a
mar
ine
anim
al t
hat
cou
ld b
e at
th
e to
p of
th
e m
arin
e fo
od w
eb p
ictu
red
on t
he
prev
iou
s pa
ge, w
ith
arr
ows
lin
kin
g it
to
both
th
e se
a ot
ter
and
stri
ped
bass
.5.
Wh
y is
a p
yram
id a
goo
d sh
ape
for
a di
agra
m t
hat
sh
ows
how
en
ergy
mov
es fr
om o
ne
feed
ing
leve
l to
the
nex
t in
a fo
od c
hai
n?
Be
sure
you
r an
swer
incl
ude
s th
e w
ord
ener
gy.
Fig
ure
5.4
: Use
th
is f
igu
re t
o an
swer
qu
esti
ons
2 an
d 3
.
94U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
5.5
: Gra
y se
als
and
har
bor
seal
s co
mpe
te f
or t
he
sam
e fo
od o
ff t
he
coas
t of
Sab
le I
slan
d i
n N
ova
Sco
tia.
com
petit
ion
- hap
pens
whe
n m
embe
rs o
f an
ecos
yste
m d
epen
d on
the
sam
e lim
ited
supp
ly o
f foo
d.
pred
ator
s - a
nim
als
that
hun
t and
fe
ed o
n ot
her a
nim
als.
prey
- an
imal
s th
at a
re k
illed
for
food
by
a pr
edat
or.
sym
bios
is -
an in
tera
ctio
n w
here
tw
o sp
ecie
s liv
e to
geth
er fo
r a lo
ng
time
and
at le
ast o
ne o
f the
sp
ecie
s be
nefit
s.
5.3
Ecos
yste
ms—
a N
atur
al B
alan
ce
Th
e w
ays
that
livi
ng
thin
gs in
a e
cosy
stem
rel
ate
to o
ne
anot
her
cre
ates
a n
atu
ral
bala
nce
. Mos
t of
th
e re
lati
onsh
ips
in a
n e
cosy
stem
invo
lve
food
. Oth
er in
tera
ctio
ns
are
affe
cted
by
hu
man
act
ivit
y in
pos
itiv
e an
d n
egat
ive
way
s.
Type
s of
inte
ract
ions
Com
petit
ion
Mem
bers
of
an e
cosy
stem
oft
en c
ompe
te f
or f
ood.
Com
petit
ion
hap
pen
s w
hen
tw
o or
mor
e sp
ecie
s de
pen
d on
th
e sa
me
food
sou
rce
or a
ny
lim
ited
res
ourc
e. F
or e
xam
ple,
on
Sab
le I
slan
d of
f th
e co
ast
of N
ova
Sco
tia,
gra
y se
als
and
har
bor
seal
s co
mpe
te f
or t
he
sam
e fo
od (
Fig
ure
5.5
). B
oth
typ
es o
f se
als
feed
on
tin
y fi
sh c
alle
d sa
nd
la
nce
s. S
cien
tist
s h
ave
disc
over
ed t
hat
gra
y se
als
dig
into
th
e oc
ean
flo
or t
o fi
nd
the
fish
hid
ing
ther
e. H
arbo
r se
als
foll
ow
sch
ools
of
san
d la
nce
s an
d ea
t fi
sh t
hat
wan
der
away
fro
m t
he
sch
ool.
Th
e gr
ay s
eals
are
th
rivi
ng,
bu
t th
e h
arbo
r se
al p
opu
lati
on
has
bee
n d
ecre
asin
g. T
he
gray
sea
ls s
eem
to
hav
e a
mor
e su
cces
sfu
l fee
din
g be
hav
ior,
an
d th
ey a
re w
inn
ing
the
com
peti
tion
.
Pred
ator
-pre
y re
latio
nshi
psS
har
ks in
Sab
le I
slan
d’s
offs
hor
e w
ater
s ar
e kn
own
to
eat
seal
s.
An
imal
s th
at h
un
t an
d fe
ed o
n o
ther
an
imal
s ar
e ca
lled
pre
dato
rs.
In t
his
exa
mpl
e, t
he
shar
ks a
re p
reda
tors
an
d th
e se
als
are
prey
. T
he
shar
ks li
ke t
o ea
t bo
th k
inds
of
seal
s, b
ut
har
bor
seal
s ar
e sm
alle
r an
d ea
sier
to
catc
h. P
reda
tor-
prey
rel
atio
nsh
ips
hel
p ke
ep
a n
atu
ral b
alan
ce in
an
eco
syst
em.
Sym
bios
isT
her
e ar
e m
any
case
s w
her
e tw
o di
ffer
ent
type
s of
livi
ng
thin
gs
live
clo
sely
tog
eth
er f
or lo
ng
peri
ods
of t
ime.
Th
is t
ype
of
inte
ract
ion
is c
alle
d sy
mbi
osis
. In
sym
bios
is, a
t le
ast
one
mem
ber
alw
ays
ben
efit
s fr
om t
he
inte
ract
ion
. A r
emor
a is
a s
mal
l fis
h t
hat
fo
llow
s sh
arks
aro
un
d an
d ea
ts t
hei
r sc
raps
. Th
e re
mor
a be
nef
its
from
th
e sh
ark,
bu
t th
e sh
ark
does
not
ben
efit
fro
m t
he
rem
ora.
955.
3 EC
OSY
STEM
S—A
NA
TUR
AL
BA
LAN
CE
CH
APT
ER 5
: EC
OSY
STEM
S
Popu
latio
nsW
hat i
s a
popu
latio
n?A
pop
ulat
ion
is a
gro
up
of in
divi
dual
s of
th
e sa
me
spec
ies
livi
ng
in
a gi
ven
are
a. A
pop
ula
tion
of
clov
er p
lan
ts in
a t
ray
con
sist
s of
th
e to
tal n
um
ber
of p
lan
ts in
th
at t
ray.
A p
opu
lati
on o
f clo
ver
plan
ts in
a
fiel
d co
nsi
sts
of t
he
tota
l nu
mbe
r of
pla
nts
in t
hat
fie
ld
(Fig
ure
5.7
).
Grow
th ra
teP
opu
lati
ons
chan
ge a
s ol
d m
embe
rs d
ie a
nd
new
mem
bers
are
bor
n.
In n
atu
re, p
opu
lati
ons
ofte
n s
tay
abou
t th
e sa
me
size
fro
m y
ear
to
year
. Oth
er t
imes
, pop
ula
tion
s gr
ow o
r de
clin
e ve
ry f
ast.
Th
e ch
ange
in s
ize
of a
pop
ula
tion
ove
r ti
me
is c
alle
d it
s gr
owth
rate
. G
row
th r
ates
can
be
posi
tive
, neg
ativ
e, o
r n
eutr
al. T
he
grap
h b
elow
sh
ows
the
grow
th r
ate
of t
he
hu
man
pop
ula
tion
. Wh
at c
an y
ou t
ell
abou
t h
um
an p
opu
lati
on g
row
th f
rom
th
is g
raph
?
Lim
its to
po
pulat
ion
grow
th
In o
rder
to
grow
, a p
opu
lati
on n
eeds
en
ergy
, nu
trie
nts
, an
d sp
ace.
E
ner
gy a
nd
nu
trie
nts
bot
h c
ome
from
foo
d. T
her
efor
e, p
opu
lati
on
grow
th is
lim
ited
by
the
amou
nt
of f
ood
avai
labl
e. P
opu
lati
on
grow
th is
als
o li
mit
ed b
y sp
ace.
Dif
fere
nt
orga
nis
ms
requ
ire
diff
eren
t am
oun
ts o
f spa
ce in
wh
ich
to
live
. If a
ny
of t
hes
e va
riab
les
are
too
lim
ited
, a p
opu
lati
on w
ill n
ot c
onti
nu
e to
gro
w.
Fig
ure
5.6
: Tw
o d
iffe
ren
t po
pula
tion
s of
clo
ver
plan
ts.
popu
latio
n - a
gro
up o
f in
divi
dual
s of
the
sam
e sp
ecie
s liv
ing
in a
giv
en a
rea.
grow
th ra
te -
the
chan
ge in
siz
e of
a p
opul
atio
n ov
er ti
me.
96U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
5.7
: Th
e E
uro
pean
gre
en
crab
.
A s
peci
es o
f bar
nacl
e is
a p
aras
ite
of th
e gr
een
crab
in it
s na
tive
com
mun
ity (E
urop
e an
d N
orth
A
frica
). Th
e ba
rnac
les
wea
ken
som
e of
the
crab
s an
d pr
even
t th
em fr
om re
prod
ucin
g. T
his
help
s ke
ep th
e gr
een
crab
’s p
opul
atio
n in
bal
ance
in it
s na
tive
envi
ronm
ent.
Use
this
info
rmat
ion
to p
ropo
se a
way
of c
ontro
lling
the
gree
n cr
ab p
opul
atio
n in
the
Uni
ted
Stat
es. W
rite
dow
n th
e pr
os
and
cons
of y
our p
ropo
sal.
Inva
sive
spe
cies
Orga
nism
sin
tera
ct in
an
area
Th
e in
tera
ctio
ns
amon
g or
gan
ism
s in
an
eco
syst
em c
reat
e a
nat
ura
l bal
ance
in t
hei
r po
pula
tion
s. T
his
bal
ance
is p
artl
y m
ain
tain
ed b
y pr
edat
or-p
rey
rela
tion
ship
s an
d co
mpe
titi
on f
or
food
. Som
etim
es a
spe
cies
th
at d
oesn
’t be
lon
g fi
nds
its
way
into
a
new
are
a. S
uch
a s
peci
es is
oft
en c
alle
d an
in
vasi
ve s
peci
es. A
sp
ecie
s is
reg
arde
d as
inva
sive
if it
has
bee
n in
trod
uce
d to
a r
egio
n
wh
ere
it d
id n
ot p
revi
ousl
y oc
cur
nat
ura
lly.
In
vasi
ve s
peci
es, i
f su
cces
sfu
l, ca
n u
pset
th
e in
tera
ctio
ns
that
cre
ate
the
nat
ura
l ba
lan
ce.
The E
urop
ean
gree
n cr
abT
he
Eu
rope
an g
reen
cra
b is
a n
ativ
e of
th
e co
asts
of
Eu
rope
an
d N
orth
ern
Afr
ica
(Fig
ure
5.7
). G
reen
cra
bs h
ave
been
fou
nd
on b
oth
th
e E
ast
and
Wes
t co
asts
of
the
Un
ited
Sta
tes.
Sci
enti
sts
thin
k th
ey a
re t
ran
spor
ted
in c
argo
sh
ips
carr
yin
g se
awat
er f
rom
oth
er
regi
ons.
Th
e ar
riva
l of
the
gree
n c
rab
in a
new
are
a is
cau
se f
or
con
cern
. Th
ese
smal
l cra
bs c
ould
ch
ange
an
y ec
osys
tem
th
ey e
nte
r.
In t
he
1950
s, t
hey
wer
e bl
amed
for
th
e de
stru
ctio
n o
f so
ft-s
hel
l cl
am p
opu
lati
ons
in M
ain
e.
How
mig
ht g
reen
cr
abs a
ffect
ot
hers
?
Gre
en c
rabs
eat
man
y ty
pes
of o
rgan
ism
s in
clu
din
g cl
ams,
m
uss
els,
an
d th
e yo
un
g of
oth
er c
rab
spec
ies.
Stu
dies
hav
e sh
own
th
at t
he
gree
n c
rab
is m
uch
qu
icke
r an
d a
bett
er p
reda
tor
than
m
ost
oth
er c
rabs
. How
do
you
th
ink
the
pres
ence
of
gree
n c
rabs
m
igh
t af
fect
oth
er t
ypes
of
orga
nis
ms?
Incr
ease
dco
mpe
titio
nO
ne
way
is t
hro
ugh
incr
ease
d co
mpe
titi
on a
mon
g di
ffer
ent
spec
ies
for
food
. Wh
en in
trod
uce
d in
to a
new
are
a, t
he
gree
n c
rab
com
pete
s w
ith
nat
ive
spec
ies
of c
rabs
for
th
e sa
me
food
. If
the
gree
n c
rab
is m
ore
succ
essf
ul,
it m
ay t
ake
food
aw
ay f
rom
nat
ive
crab
spe
cies
. Th
is m
ay c
ause
neg
ativ
e po
pula
tion
gro
wth
for
th
e n
ativ
e sp
ecie
s.
975.
3 EC
OSY
STEM
S—A
NA
TUR
AL
BA
LAN
CE
CH
APT
ER 5
: EC
OSY
STEM
S
Pollu
tant
sW
hat i
s a
pollu
tant
?H
um
an a
ctiv
itie
s af
fect
eco
syst
ems
in b
oth
pos
itiv
e an
d n
egat
ive
way
s. O
ne
neg
ativ
e ef
fect
is p
ollu
tion
. A p
ollu
tant
is s
omet
hin
g th
at c
ause
s h
arm
to
a li
vin
g th
ing.
Th
ree
thin
gs o
ften
det
erm
ine
how
har
mfu
l a p
ollu
tan
t is
:
1.th
e po
llu
tan
t’s a
bili
ty t
o ca
use
har
m
2.th
e am
oun
t of
pol
luta
nt
in t
he
air,
wat
er, o
r so
il
3.h
ow lo
ng
the
poll
uta
nt
stay
s in
th
e ai
r, w
ater
, or
soil
Sulfu
r dio
xide i
s a p
ollu
tant
Su
lfu
r di
oxid
e is
a c
hem
ical
th
at is
a g
ood
exam
ple
of a
pol
luta
nt
(Fig
ure
5.8
). W
hen
su
lfu
r di
oxid
e is
pre
sen
t in
larg
e am
oun
ts in
th
e ai
r, it
can
mak
e br
eath
ing
diff
icu
lt e
ven
for
hea
lth
y pe
ople
. It
also
re
acts
wit
h w
ater
in t
he
atm
osph
ere
to m
ake
acid
rai
n. A
cid
rain
ca
n k
ill t
rees
an
d h
arm
life
in la
kes,
pon
ds, a
nd
stre
ams.
Su
lfu
r di
oxid
e en
ters
th
e ai
r fr
om f
ossi
l fu
el p
ower
pla
nts
, au
tom
obil
es,
and
even
vol
can
oes.
Merc
ury i
s a
pollu
tant
Mer
cury
is a
n e
lem
ent
that
can
be
fou
nd
nat
ura
lly
in a
n e
cosy
stem
. H
um
an a
ctiv
itie
s li
ke in
dust
ry a
lso
cau
se t
he
rele
ase
of m
ercu
ry
into
th
e en
viro
nm
ent.
It
is t
aken
in b
y m
embe
rs o
f an
eco
syst
em
and
it b
uil
ds u
p in
th
eir
bodi
es. W
hen
th
e am
oun
t of
mer
cury
in a
li
vin
g or
gan
ism
get
s h
igh
en
ough
, th
e an
imal
or
plan
t ca
n b
e h
arm
ed a
nd
may
eve
n d
ie. M
ercu
ry is
com
mon
ly f
oun
d in
fis
h.
Bec
ause
mer
cury
is s
tore
d u
p in
th
e fa
tty
tiss
ues
of t
he
fish
ove
r it
s en
tire
life
tim
e, t
he
leve
l of
the
mer
cury
in t
he
fish
may
be
thou
san
ds o
f ti
mes
hig
her
th
an t
he
leve
l of
the
mer
cury
in t
he
wat
er. T
his
pro
cess
, kn
own
as
biom
agn
ific
atio
n, i
s ex
plai
ned
on
th
e n
ext
page
.F
igu
re 5
.8: S
ulf
ur
dio
xid
e is
a
poll
uta
nt.
pollu
tant
- a
varia
ble
that
cau
ses
harm
to a
n or
gani
sm.
98U
NIT
2 O
RG
AN
ISM
SA
ND
THE
ENVI
RO
NM
ENT
Fig
ure
5.9
: Som
e po
wer
pla
nts
sen
d
mer
cury
in
to t
he
air.
Th
is e
ven
tual
ly
fall
s to
Ear
th w
ith
th
e ra
in a
nd
en
ds
up
in l
akes
an
d o
cean
s.
Fig
ure
5.1
0: T
he
pyra
mid
sh
ows
how
tox
ins
are
con
cen
trat
ed a
t ea
ch li
nk
in a
foo
d c
hai
n.
Toxi
ns in
the
food
cha
inW
hat a
re to
xins?
Hu
man
act
ivit
ies
som
etim
es c
reat
e to
xic
poll
uta
nts
(to
xin
s). H
igh
co
nce
ntr
atio
ns
of t
oxin
s m
ay im
pact
livi
ng
thin
gs. T
oxin
s ca
n
cau
se s
low
ed g
row
th, d
ecre
ased
rep
rodu
ctio
n, a
nd
even
dea
th.
Wh
en t
oxin
s en
ter
ecos
yste
ms,
th
ey s
prea
d ou
t an
d be
com
e le
ss
con
cen
trat
ed. S
ome
toxi
ns
end
up
in la
kes
and
ocea
ns
(Fig
ure
5.9
).
Foo
d ch
ain
s co
nce
ntr
ate
som
e to
xic
poll
uta
nts
, lik
e m
ercu
ry, i
nto
th
e ti
ssu
es o
f an
imal
s. T
o u
nde
rsta
nd
how
th
is h
appe
ns,
let’s
look
at
a m
arin
e fo
od c
hai
n.
Conc
entra
tion
of
toxin
sT
oxin
s ar
e co
nce
ntr
ated
at
each
lin
k in
a f
ood
chai
n. A
s pr
odu
cers
m
ake
food
, th
ey a
bsor
b m
olec
ule
s of
tox
ins
from
th
e w
ater
. Nex
t,
her
bivo
res
eat
larg
e n
um
bers
of
prod
uce
rs. T
oxin
s li
ke m
ercu
ry
diss
olve
in f
at, n
ot w
ater
. Th
ey a
re s
tore
d in
th
e fa
tty
tiss
ues
of
her
bivo
res
and
are
not
pas
sed
out
of t
hei
r bo
dies
.
Toxin
s can
be
pass
ed o
n to
of
fspr
ing
Wh
en c
arn
ivor
es e
at m
any
her
bivo
res,
th
ey a
ccu
mu
late
eve
n
hig
her
leve
ls o
f to
xin
s in
th
eir
tiss
ues
. Sec
onda
ry c
arn
ivor
es, w
ho
prey
on
oth
er c
arn
ivor
es, c
an a
ccu
mu
late
dan
gero
us
leve
ls o
f to
xin
s. T
hes
e to
xin
s ca
n s
omet
imes
be
pass
ed o
n t
o th
eir
you
ng.
F
igu
re 5
.10
show
s h
ow t
he
amou
nt
of a
tox
in c
an m
ult
iply
as
it
trav
els
up
the
food
ch
ain
.
995.
3 EC
OSY
STEM
S—A
NA
TUR
AL
BA
LAN
CE
CH
APT
ER 5
: EC
OSY
STEM
S
Wat
er q
ualit
yMa
rine a
nd
fresh
wate
rec
osys
tem
s
Eve
n if
you
live
far
inla
nd,
you
are
par
t of
a f
resh
wat
er e
cosy
stem
. W
e de
pen
d on
fre
sh w
ater
for
dri
nki
ng,
for
sta
yin
g cl
ean
, an
d fo
r fa
rmin
g an
d in
dust
ries
. Hu
man
s ca
n’t
live
apa
rt fr
om a
fres
hw
ater
ec
osys
tem
!
Wat
er q
ualit
y te
stin
gB
ecau
se c
lean
wat
er is
so
impo
rtan
t to
ou
r da
ily
live
s, w
e m
ust
pr
otec
t th
e h
ealt
h o
f fre
shw
ater
eco
syst
ems.
Gov
ern
men
ts a
nd
civi
c gr
oups
tes
t th
e qu
alit
y of
su
rfac
e w
ater
reg
ula
rly
(Fig
ure
5.1
1).
Th
ey u
se t
he
data
to
mon
itor
th
e qu
alit
y of
th
e w
ater
.
Obse
rvin
g a
body
of w
ater
To
lear
n a
bou
t th
e w
ater
qu
alit
y of
a p
ond,
riv
er, o
r la
ke, y
ou w
ould
fi
rst
mak
e ca
refu
l obs
erva
tion
s. Y
ou m
igh
t as
k, “
Wh
at d
oes
the
pon
d w
ater
look
like
or
smel
l lik
e? W
hat
an
imal
s an
d pl
ants
are
li
vin
g in
th
e po
nd?
Wh
ere
is t
he
pon
d lo
cate
d? A
re t
her
e h
ouse
s or
fa
rms
nea
rby?
Is
the
pon
d n
ear
a fa
ctor
y?”
Com
mon
tes
ts u
sed
to
see
if s
urf
ace
wat
er is
hea
lth
y ar
e de
scri
bed
belo
w.
Tem
pera
ture
Th
e w
ater
tem
pera
ture
of
a po
nd
is m
easu
red
thre
e or
mor
e in
ches
be
low
th
e su
rfac
e of
th
e w
ater
. Th
e h
igh
er t
he
wat
er t
empe
ratu
re,
the
less
dis
solv
ed o
xyge
n t
her
e m
ay b
e in
th
e w
ater
. Dis
solv
ed
oxyg
en is
nee
ded
by m
ost
orga
nis
ms
livi
ng
in t
he
pon
d.
Turb
idity
test
Th
e tu
rbid
ity
test
mea
sure
s th
e cl
oudi
nes
s of
wat
er. I
f th
e w
ater
is
clou
dy d
ue
to s
usp
ende
d se
dim
ent,
su
nli
ght
is b
lock
ed, a
nd
pon
d pl
ants
do
not
gro
w w
ell.
Th
is c
an b
e h
arm
ful,
beca
use
pon
d pl
ants
ar
e n
eede
d as
foo
d fo
r ot
her
livi
ng
thin
gs in
th
e po
nd.
A s
ecch
i d
isk
prov
ides
an
eas
y w
ay t
o m
easu
re t
urb
idit
y (F
igu
re 5
.12)
. Th
e di
sk
is lo
wer
ed in
to t
he
wat
er u
nti
l th
e bl
ack
and
wh
ite
pan
els
are
no
lon
ger
visi
ble
to a
per
son
look
ing
into
th
e w
ater
. Th
e ro
pe h
oldi
ng
the
disk
is m
arke
d at
met
er a
nd
hal
f-m
eter
inte
rval
s to
mea
sure
th
e de
pth
of
the
disk
wh
en it
dis
appe
ars
from
vie
w u
nde
rwat
er.
Fig
ure
5.1
1: T
esti
ng
wat
er q
ual
ity
in a
pon
d e
cosy
stem
.
Fig
ure
5.1
2: A
Sec
chi
dis
k.
100
UN
IT 2
OR
GA
NIS
MS
AN
DTH
E EN
VIR
ON
MEN
T
Fig
ure
5.1
3: T
he
pH v
alu
es o
f so
me
com
mon
sol
uti
ons.
Th
e pH
of
a so
luti
on
is a
mea
sure
of
how
aci
dic
(pH
0 t
o 7)
or
basi
c (p
H 7
to
14)
it i
s.
Mor
e w
ater
qua
lity
test
sDi
ssol
ved
oxyg
en te
stO
xyge
n e
nte
rs f
resh
wat
er f
rom
th
e ai
r an
d th
e ph
otos
ynth
esis
of
aqu
atic
pla
nts
an
d m
icro
scop
ic o
rgan
ism
s ca
lled
ph
ytop
lan
kton
. W
ater
qu
alit
y is
hig
her
wh
en d
isso
lved
oxy
gen
leve
ls a
re h
igh
. W
ater
sam
ples
for
a d
isso
lved
oxy
gen
tes
t sh
ould
be
take
n a
way
fr
om t
he
wat
er’s
edg
e an
d ab
out
thre
e in
ches
bel
ow t
he
surf
ace.
Biol
ogica
lox
ygen
dem
and
test
Th
e bi
olog
ical
oxy
gen
dem
and
tes
t is
a t
wo-
part
tes
t. T
wo
wat
er
sam
ples
are
tak
en a
t th
e sa
me
tim
e. D
isso
lved
oxy
gen
is m
easu
red
in t
he
firs
t sa
mpl
e ri
ght
away
. Th
e se
con
d sa
mpl
e is
sh
ield
ed fr
om
ligh
t an
d m
easu
red
at a
late
r ti
me.
Th
e am
oun
t of
oxy
gen
in t
he
firs
t an
d se
con
d sa
mpl
es is
com
pare
d to
fin
d ou
t h
ow m
uch
oxy
gen
w
as u
sed
by b
acte
ria
as t
hey
dec
ompo
se o
rgan
ic m
ater
ial.
Nitra
te an
d ph
osph
ate t
ests
Nit
rate
s an
d ph
osph
ates
are
ch
emic
als
that
can
en
ter
pon
ds t
hat
ar
e n
ear
farm
s, fe
rtil
ized
law
ns,
or
sept
ic t
anks
. Exc
ess
nit
rate
s or
ph
osph
ates
can
cau
se la
rge
grow
ths
of a
lgae
, a t
ype
of r
ootl
ess,
st
emle
ss p
lan
t co
mm
only
fou
nd
in p
onds
. Dec
ompo
sers
feed
on
th
e de
cayi
ng
alga
e an
d u
se u
p va
luab
le o
xyge
n. T
his
en
dan
gers
th
e h
ealt
h o
f th
e po
nd
ecos
yste
m.
pH te
stT
he
pH s
cale
ran
ges
from
0 t
o 14
(Fig
ure
5.1
3). P
ure
wat
er is
pH
7
(neu
tral
). S
urf
ace
wat
er r
ange
s fr
om a
bou
t 6.
5 to
8.5
. Mos
t or
gan
ism
s in
an
aqu
atic
eco
syst
em f
un
ctio
n b
est
wh
en t
he
wat
er
pH is
abo
ut
7. M
any
life
pro
cess
es d
o n
ot fu
nct
ion
wel
l wh
en p
H is
to
o h
igh
or
low
. For
exa
mpl
e, f
ish
hav
e tr
oubl
e re
prod
uci
ng
wh
en
the
pH o
f th
eir
wat
er e
nvi
ron
men
t is
too
low
(ac
idic
).
Sum
mar
yT
hes
e w
ater
qu
alit
y te
sts
hel
p m
ake
sure
th
at t
he
wat
er w
e n
eed
stay
s cl
ean
an
d sa
fe. W
hen
tes
t re
sult
s sh
ow t
hat
a b
ody
of w
ater
is
un
hea
lth
y, g
over
nm
ent
and
civi
c gr
oups
can
wor
k to
geth
er t
o fi
nd
the
cau
ses
and
deci
de h
ow t
o m
ake
the
aqu
atic
eco
syst
em
hea
lth
y on
ce a
gain
.
101
5.3
ECO
SYST
EMS—
A N
ATU
RA
L B
ALA
NC
E
CH
APT
ER 5
: EC
OSY
STEM
S
5.3
Sect
ion
Rev
iew
1.R
ead
each
des
crip
tion
of
an e
cosy
stem
inte
ract
ion
an
d de
cide
w
het
her
it is
an
exa
mpl
e of
com
peti
tion
, pre
dat
or-p
rey
rela
tion
ship
, or
sym
bios
is.
a.S
wee
t po
tato
pla
nts
rel
ease
ch
emic
als
that
kee
p ot
her
n
earb
y pl
ants
fro
m g
row
ing.
b.T
ickb
irds
sit
on
a b
lack
rh
inoc
eros
an
d fe
ed o
n t
he
tick
s th
at
infe
st t
he
thic
k sk
in o
f th
e rh
ino.
Th
e rh
ino
ben
efit
s be
cau
se
it g
ets
tick
s re
mov
ed f
rom
its
body
; th
e ti
ckbi
rds
ben
efit
be
cau
se t
hey
hav
e a
sou
rce
of f
ood.
c.A
haw
k ca
ptu
res
and
eats
a r
abbi
t.
2.N
ame
one
type
of a
ir p
ollu
tan
t an
d on
e ty
pe o
f wat
er p
ollu
tan
t.
Wh
y ar
e th
ese
subs
tan
ces
har
mfu
l to
air
and
wat
er?
3.W
ater
qu
alit
y is
ver
y im
port
ant
to t
he
hea
lth
of
a po
nd.
C
ompl
ete
the
wat
er q
ual
ity
test
ch
art
that
has
bee
n s
tart
ed fo
r yo
u. B
e su
re t
o fi
ll in
all
th
e bl
anks
!
Wat
er Q
ualit
y Te
stW
hat i
t tes
ts fo
rR
esul
ts fo
r a h
ealth
y po
nd
Tem
pera
ture
How
war
m o
r col
d th
e w
ater
is
Coo
ler w
ater
has
mor
e ox
ygen
ava
ilabl
e fo
r liv
ing
thin
gs th
an w
arm
er w
ater
Turb
idity
The
clou
dine
ss o
f th
e w
ater
Cle
ar w
ater
allo
ws
sunl
ight
to
get
to th
e po
nd p
lant
s,
whi
ch h
elps
them
gro
wD
isso
lved
oxy
gen
Nitr
ates
pH
Bla
ck-T
aile
d Pr
airie
Dog
Ake
ysto
ne s
peci
es is
a s
peci
es
who
se e
xtin
ctio
n co
uld
lead
to th
e ex
tinct
ion
of o
ther
spe
cies
in it
s ec
osys
tem
. A k
eyst
one
spec
ies
help
s su
stai
n th
e ec
osys
tem
to
whi
ch it
bel
ongs
.
The
blac
k-ta
iled
prai
rie d
og is
a
keys
tone
spe
cies
in a
pra
irie
ecos
yste
m. D
o so
me
rese
arch
to fi
nd a
t lea
st th
ree
reas
ons
why
th
is a
nim
al is
con
side
red
a ke
ysto
ne s
peci
es.
102
Food
Web
s of
the
Dee
pT
he
expl
orer
s de
scen
d ov
er 1
.5 m
iles
into
th
e da
rk, c
old,
cr
ush
ing
ocea
n. S
udd
enly
, th
e li
ghts
fro
m t
hei
r su
bmer
sibl
e sh
ine
on a
tal
l ch
imn
ey-l
ike
stac
k th
at s
pew
s h
ot, b
lack
w
ater
. Wh
at t
he
expl
orer
s se
e n
ext
is e
ven
mor
e am
azin
g.
An
abu
nda
nt
com
mu
nit
y of
life
su
rrou
nds
th
e u
nde
rsea
vo
lcan
ic v
ent!
Six
foot
lon
g tu
be w
orm
s, c
rabs
, cla
ms,
an
d al
l so
rts
of c
reat
ure
s th
rive
in t
his
har
sh e
nvi
ron
men
t. O
n t
his
de
ep s
ea e
xped
itio
n in
197
7, s
cien
tist
s di
scov
ered
a s
tran
ge
com
mu
nit
y of
livi
ng
thin
gs t
hat
for
ever
ch
ange
d ou
r u
nde
rsta
ndi
ng
of E
arth
’s f
ood
web
s.
Wha
t is
a H
ydro
ther
mal
Ven
t? A h
ydro
ther
mal
ven
t is
an
u
nde
rwat
er v
ersi
on o
f a
geys
er. A
t so
me
plac
es a
lon
g oc
ean
flo
or r
idge
s, E
arth
’s
gian
t cr
ust
al p
late
s ar
e m
ovin
g ap
art,
cre
atin
g cr
acks
an
d cr
evic
es t
hat
ex
pose
mol
ten
roc
k. W
hen
se
awat
er s
eeps
into
th
ese
crac
ks, i
t is
hea
ted
and
then
vi
olen
tly
spew
s ou
t in
to t
he
surr
oun
din
g oc
ean
. Th
e te
mpe
ratu
re o
f th
e w
ater
th
at g
ush
es o
ut
of a
h
ydro
ther
mal
ven
t ca
n
reac
h 3
00 d
egre
es C
elsi
us!
H
ydro
ther
mal
ven
ts a
re
fou
nd
at v
ery
grea
t de
pth
s,
wh
ere
no
sun
ligh
t pe
net
rate
s. H
ow c
ould
livi
ng
thin
gs
poss
ibly
th
rive
nea
r h
ot, c
orro
sive
wat
er -
an
d w
ith
no
sun
ligh
t?
Che
mos
ynth
esis
Ph
otos
ynth
esis
is im
poss
ible
at
the
dark
dep
ths
of a
h
ydro
ther
mal
ven
t. T
he
orga
nis
ms
that
th
rive
th
ere
can
not
re
ly o
n p
hot
osyn
thes
is f
or t
hei
r so
urc
e of
en
ergy
. In
stea
d,
they
rel
y on
a p
roce
ss c
alle
d ch
emos
ynth
esis
. In
ch
emos
ynth
esis
, en
ergy
is p
rodu
ced
thro
ugh
ch
emic
al
reac
tion
s. T
he
prod
uce
rs in
th
is e
cosy
stem
are
bac
teri
a. T
he
bact
eria
use
en
ergy
rel
ease
d fr
om a
ch
emic
al r
eact
ion
in
volv
ing
sulf
ur
com
pou
nds
su
ch a
s h
ydro
gen
su
lfid
e.
Hyd
roge
n s
ulf
ide
is t
he
chem
ical
th
at s
mel
ls li
ke r
otte
n e
ggs,
an
d is
fou
nd
in la
nd
ecos
yste
ms
too
- esp
ecia
lly
swam
ps. I
t is
ab
un
dan
t at
a h
ydro
ther
mal
ven
t be
cau
se t
he
hot
wat
er
diss
olve
s m
iner
als
and
leav
es d
epos
its
of s
ulf
ur
com
pou
nds
.
Bac
teria
inst
ead
of p
lant
sP
lan
ts a
re t
he
prod
uce
rs o
f m
ost
ecos
yste
ms,
bu
t at
a
hyd
roth
erm
al v
ent,
ba
cter
ia a
re t
he
prod
uce
rs. T
his
is
quit
e u
nu
sual
, bu
t th
ere
is s
omet
hin
g el
se v
ery
un
iqu
e ab
out
thes
e pr
odu
cers
. Nea
rly
thre
e fo
urt
hs
of a
ll
the
chem
osyn
thet
ic
bact
eria
at
the
ven
t ac
tual
ly l
ive
insi
de
the
tiss
ues
of
anim
als,
like
tu
be w
orm
s (s
how
n a
bove
) an
d m
ollu
sks.
Oth
er b
acte
ria
grow
in p
lum
es in
th
e su
perh
eate
d w
ater
gey
ser
and
are
eate
n b
y ot
her
an
imal
s. S
till
mor
e ba
cter
ia f
orm
sli
my
mat
s ov
er a
ll t
he
surf
aces
aro
un
d th
e ve
nt.
Chapter 5 Connection
103
UN
IT 2
OR
GA
NIS
MS
AN
DTH
E EN
VIR
ON
MEN
T
A U
niqu
e Fo
od W
ebA
ll s
orts
of s
tran
ge a
nd
fan
tast
ic a
nim
als
feed
on
th
e ba
cter
ia a
t h
ydro
ther
mal
ven
ts. T
iny
segm
ente
d w
orm
s as
th
in a
s a
piec
e of
th
read
eat
th
e m
at-
form
ing
bact
eria
. Sn
ails
an
d li
mpe
ts g
raze
on
th
e m
at-f
orm
ing
bact
eria
too
. Exo
tic
tube
wor
ms
as
mu
ch a
s si
x fe
et t
all a
re a
nch
ored
to
the
bott
om.
Th
ey h
ave
no
mou
th o
r gu
t! T
hey
rec
eive
th
eir
food
fr
om t
he
chem
osyn
thet
ic b
acte
ria
that
live
in t
hei
r ti
ssu
es. T
his
is q
uit
e an
inte
rest
ing
arra
nge
men
t,
don
’t yo
u t
hin
k? E
el-l
ike
ven
t fi
sh a
re v
orac
iou
s ca
rniv
ores
. Cra
bs a
nd
shri
mp
scav
enge
th
e ve
nt
for
thei
r m
eals
. An
occ
asio
nal
oct
opu
s w
ill v
isit
th
e h
ydro
ther
mal
ven
t co
mm
un
ity
- lo
okin
g fo
r a
tast
y m
eal,
of c
ours
e!
Vent
Res
earc
hR
esea
rch
ers
are
inte
rest
ed in
stu
dyin
g lo
ts o
f di
ffer
ent
char
acte
rist
ics
of h
ydro
ther
mal
ven
t co
mm
un
itie
s. O
ne
very
inte
rest
ing
prop
osal
is t
he
poss
ibil
ity
that
hyd
roth
erm
al v
ents
hol
d so
me
clu
es
to t
he
mys
tery
of
the
orig
in o
f li
fe o
n E
arth
. Oth
er
rese
arch
ers
are
sear
chin
g h
ydro
ther
mal
ven
ts f
or
med
ical
cu
res.
Sti
ll o
ther
s ar
e st
udy
ing
the
actu
al
ven
t fo
r w
hat
it c
an t
each
us
abou
t E
arth
’s la
yers
an
d in
tern
al e
ner
gy. P
erh
aps
one
day
you
mig
ht
stu
dy t
he
stra
nge
com
mu
nit
y of
a h
ydro
ther
mal
ve
nt.
Que
stio
ns:
1.W
hy w
ere
scie
ntis
ts s
o su
rpris
ed to
dis
cove
r liv
ing
thin
gs a
t a h
ydro
ther
mal
ven
t?2.
Wha
t is
chem
osyn
thes
is?
How
is it
diff
eren
t fro
m p
hoto
synt
hesi
s?3.
Stud
y th
e hy
drot
herm
al fo
od w
eb d
iagr
am a
nd a
nsw
er th
ese
ques
tions
: (a)
Wha
t org
anis
ms
form
the
base
of t
his
food
web
? (b
)Prim
ary
cons
umer
s fe
ed o
n th
e fo
od w
eb p
rodu
cers
. Lis
t the
prim
ary
cons
umer
s.(c
)Tub
e w
orm
s ha
ve n
o m
outh
or g
ut. H
ow d
o th
ey e
at?
Chapter 5 Connection
