Download The Energy of Life

The Energy of Life
Chapter 3
Elements Essential For Life
Hydrogen:
y
g
Organic
g
molecules
Carbon: Organic molecules
Nitrogen: Proteins and Nucleic Acids
Oxygen: Organic molecules
These elements account for 99% of the mass of all
living
g things.
g
Elements Essential For Life
Na
P
K
Mg
S
Ca
Si
Cl
Fe
These elements account for 1% of the mass of all living
things.
What Classifies Something As
Li i ?
Living?
•
•
All organisms
g
consist of cells.
Energy is necessary for life because living
systems use it to accomplish the processes of life:
1. Reproduction
2. Growth
3. Movement
4 Eating
4.
5 Stimulus/Response
5.
First Law of Thermodynamics: Energy cannot be created
nor destroyed. Energy can only be changed from one
form to another.
Machines
A combination of matter capable of using
energy to perform useful work.
A li
Are
living
i things
thi
machines?
hi
?
Is a machine, like a submarine, a living thing?
How Matter and Energy Enter Living
S t
Systems
Autotrophy:
p y the p
process of self-feeding
g by
y creating
g
energy-rich compounds called Carbohydrates.
Heterotrophy:
p y the p
process of obtaining
g energy-rich
gy
organic compounds by consuming other plants
and/or animals.
Respiration
The process of releasing
energy from carbohydrates to
perform
f
th
the functions
f
ti
off life.
lif
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
Photosynthesis
Process of using
g light
g energy
gy to create carbohydrates
y
from inorganic compounds.
During photosynthesis, organisms use light energy to
di
disassemble
bl carbon
b dioxide
di id and
d water
t molecules,
l
l
rebuilding them into carbohydrates.
Primary Producers = Autotrophs
6CO2 + 12H2O + sunlight ---> 6O 2 + C6 H12O 6 + 6H2O
Primary producers harness only about
1/2,000 of the light reaching Earth.
Aerobic respiration: respiration that uses
oxygen.
Anaerobic respiration: respiration that
does not use oxygen.
yg
Energy Cycle
Chemosynthesis
The p
process of using
g chemicals to create energy-rich
gy
organic compounds.
Both photosynthesis and chemosynthesis are forms of
fi ti – the
fixation
th process off converting,
ti
or fixing,
fi i
an
inorganic compound into a useable organic
compound.
Carbohydrates
y
In 1977, scientists diving in ALVIN, discovered
communities living
g around volcanic springs.
p g
“cold-seep” communities: primitive single-cell
organisms use methane from
f
seeps on the ocean
bottom. This process traps a lot of potential carbon
dioxide.
Beggiatoal bacterial mat
Tubeworms, soft corals and
Tubeworms
chemosynthetic mussels at a seep
located 3,000 meters down
Cold seep vs. Hydrothermal vents
(cold vents)
Cold seep
Emissions are
same temperature
Emit at slow
dependable rate
Organisms are
longer-lived
Hydrothermal
Emissions are
super-heated
Volatile and
ephemeral
environment
Organisms are
shorter-lived
The Ocean’s
Ocean s Primary Productivity
In the marine environment, two variables affect
the availability of energy.
1). Quantity of Primary Production
2). Flow of Energy
Marine Biomass
The main “products”
p
of primary
p
y production
p
are
carbohydrates.
Carbohydrates are the primary units of usable energy
i living
in
li i systems,
t
plus
l a source off carbon
b used
d in
i an
organism’s tissues.
Scientists measure primary productivity In terms of the
carbon fixed (bound) into organic material.
The unit of measurement of primary productivity is:
grams of Carbon per square meter of surface area per
year.
gC/m2/yr
The oceans’
oceans primary productivity averages from 75 to
150gC/m2/yr
Biomass: the mass of living tissue.
Standing Crop: the biomass at a given time.
The image shows ocean net primary productivity distributions from the Sea
Sea-viewing
viewing Wide Field
Field-ofof
view Sensor (SeaWiFS) data on the OrbView-2 satellite (1997-2002). The units are in grams of
Carbon per meter squared per year. Light gray areas indicate missing data. Credit: Images by
Robert Simmon, NASA GSFC Earth Observatory, based on data provided by Watson
Ocean Community
All oceans – average
Net Primary Productivity
120
Coral reef
880 - 2,200
Kelp bed
400 – 1,900
Sh lf plankton
Shelf
l kt
90 – 270
Open ocean
1 - 180
Typically, the standing crop in the oceans is one to two
billion metric tons.
Land Community
All Land – average
Net Primary Productivity
150
Rain Forest
460 – 1,600
Temperate Forest
270 – 1,140
F
Freshwater
h t Swamp
S
360 – 1,820
1 820
Cropland
45 – 1,820
Typically the standing crop on land is 600 to 1,000
billion metric tons
tons.
Turnover: the time required for the photosynthesis/
respiration cycle in an ecosystem.
The shorter the turnover time, the faster the standing
crop passes energy into the ecosystem.
ecosystem
Gross Primary Productivity (GPP): the measure of all
the organic material produced in an area by
autotrophs.
Net Primary Productivity (NPP): the quantity of energy
remaining after autotrophs have satisfied their
respiratory needs.
Plankton
A group organisms that exist adrift in ocean
currents.
2 types:
1. phytoplankton (plants)
2. zooplankton (animals)
Nekton: organisms that swim, from small
invertebrates to large whales
whales.
Benthos: organisms that live in or on the
bottom. They can move about or be sessile.
Neuston: plankton that float on the surface.
Neuston
Phytoplankton
Nekton
Benthos
Zooplankton
Diatoms
4 types
yp of p
phytoplakton:
y p
•
•
•
•
1. Diatoms:
the most efficient photosynthesizers known.
The most dominant and productive of the phytoplankton.
Characterized by a rigid cell wall made of silica.
Cell wall
wall, called a frustule
frustule, admits light much like glass
glass.
2.
Dinoflagellates:
– characterized one or two whip-like flagella which they move
to change orientation or swim vertically in water.
– Most are autotrophs.
– Some live within coral polyps and are the most significant
primary producers in the coral reef community
community.
– Principal organisms responsible for plankton blooms
because of their high reproductive rates.
3.
Coccolithophores:
–
–
–
–
single-celled
single
celled autotrophs characterized by shells of
calcium carbonate.
Shells are called coccoliths.
Li in
Live
i brightly
b i htl lit,
lit shallow
h ll
water.
t
Area with high concentrations may appear milky or
chalky.
4. Silicoflagellates:
–
charaterized by internal supporting structures made of
silica.
– Propel themselves with one long flagellum.
– Structurally
St
t
ll and
d chemically
h i ll more primitive
i iti than
th diatoms.
di t
Benthos
3 divisions:
1. epifauna – those animals that live on the sea
floor.
2. epiflora – those plants that live on the sea
floor.
floor
3. infauna – organisms that are partially or
completely buried on the sea floor.
Infauna can be:
1. Deposit feeders: feed off detritus (loose organic
or inorganic material) drifting down from above
2. Suspension feeders: filter particles (mostly
plankton)
l kt ) suspended
d d in
i the
th water
t for
f food.
f d
Limits on Marine Primary
P d ti it
Productivity
Limiting
g factors: p
physiological
y
g
or biological
g
necessities that restrict survival.
Too much or too little will reduce the population of an
organism.
i
4 Limiting factors
Depth
p
Light
Plankton Bloom
Location
Plankton Bloom
• Periods of explosive
p
reproduction
p
and growth
g
of a
particular plankton species.
• Can deplete the nutrients available in a region.
• In extreme cases, they consume all the oxygen and
release toxic by-products in such amounts that fish
and other organisms cannot survive.
• Known as “red tides.”
• Can occur naturally, but they may also be caused
when pollution eliminates a limiting factor.
Depth
• Can limit nutrients. Dead organisms that would
normally provide nutrients can sink below depths
that sunlight can’t
can t reach, making their nutrients
unavailable to photosynthesizers.
• Solution occurs when normal water motion brings
the nutrients back to shallow water.
• Water temperatures can interfere with normal
mixing.
mixing
• Waters of different temperatures resist mixing
because they have different densities.
• Also affects photosynthesis and primary productivity.
• Photoinhibition: the condition in which excess light
overwhelms an autotroph.
• Even in clear water, little photosynthesis takes place
below 100 meters (328 feet).
Some autotrophs cannot photosynthesize when the
water is too shallow. Different phytoplankton species
h
have
different
diff
t optimal
ti l depths.
d th
The less light there is, the less photosynthesis
occurs, reducing carbohydrate production. As you
go deeper autotrophs produce less carbohydrates.
• Tropical waters tend to have less productivity.
Warm upper water layer traps nutrients in the cold
layers that are too deep for photosynthesizing
autotrophs.
• In the Artic and Antarctic, there’s little temperature
differences between shallow and deep waters. This
allows nutrients to cycle to shallower water more
easily.
• In temperate regions, coastal areas tend to have
more primary productivity. There are more nutrients
f
from
rain
i runoff
ff and
d because
b
shallow
h ll
waters
t
keeps
k
them from sinking below the productive zone.
Location
Coral Reefs:
• The most efficient ecosystems on Earth.
• rely
l on dinoflagellates
di fl
ll t that
th t live
li within
ithi the
th corall
tissue rather than phytoplankton.
• Exception to the rule of low productivity of tropical
waters.
• Recycles its nutrients efficiently with very little loss
t the
to
th open sea.
Antarctic Convergence Zone:
•
Some of the highest productivity. Can be well over
200 C/ 2/yr.
200gC/m
/
How?
Long summer days
water movement bringing nutrients to
shallow water
mineral runoff
•
Short summer season makes high productivity
short-lived.
•
Arctic doesn’t have comparable productivity
intervals. It lacks landmass so fewer minerals in
Arctic waters.
Light
• Seasonal sunlight limits productivity.
• The amount of daylight affects photosynthesis and
primary productivity
productivity.
Compensation Depth
The p
point of zero net primary
p
y productivity
p
y where the
amount of carbohydrates produced exactly equals
the amount required by the autotrophs for
respiration.
respiration
• Varies with water clarity, surface disturbances, and
sun angle.
How does this affect a food chain/food web?
Energy Flow Through the
Bi
Biosphere
h
Energy enters
E
t
li
living
i systems
t
and
d the
th
biosphere through the primary
production of _____________.
p
_____________
_____________ get their energy from
consuming autotrophs or other
___________.
Autotrophs
Heterotrophs
Tropic Pyramid
A representation
p
of how energy
gy transfers from one
level of organisms to the next as they consume each
other.
10% rule
Food Webs
Shows that organisms
g
often have different choices of
prey and eat across the trophic pyramid’s theoretical
levels.
Decomposition
• Completes
p
the materials cycle
y
• Renews the inorganic materials (matter) necessary
for energy to enter life through primary production.
• Bacteria and archaea are the most important
decomposers.
• On average,
average there are 108 bacteria per liter of
seawater.