Chapter 4
Ecosystems & Energy
Ecology
 The
branch of biology that
deals with the interactions
between organisms and the
relationship between
organisms and the
environment.
Do Now:

Draw a flow chart to represent the
organizational relationships between
the following terms from the most
inclusive to the least inclusive:
ecosystem, population, species,
community, and biosphere.
Levels of Biological
Organization
Levels of Organization

Cellular
Organization
– Cells
– Tissues
– Organs
– Organ Systems
– Organisms
– SPECIES
 Ecosystem
Organization
– Species
– Population
– Community
– Ecosystem
– Landscape
– Biosphere
Species
A
group of organisms capable of
producing more members of the
same organism..
Homo sapiens with Homo sapiens
Not Homo sapiens with Homo
habilus
Species
The Brown Trout Salmo trutta
Population
 Includes
all the members
of a species found in a
given area.
 Ex: sunfish in a pond
Community
 Includes
all the populations
in a given area.
 Ex:
all plants, animals, and
microorganisms make up a
pond community
Ecosystem
 Includes
all the members of the
community plus the physical
environment in which they live
in.
–Interaction of biotic and abiotic
factors
Abiotic Factors


Nonliving factors.
The abiotic factors of an ecosystem include the
physical and chemical factors that affect the
capacity of an organism to live and reproduce.
These factors are:
1. Intensity and duration of light
2. Temperature range
3. Amount of moisture
4. Type of substrate
5. Availability of inorganic substances and gases
6. pH
Biotic Factors
 Living
factors
 These factors directly or indirectly
affect the environment.
 Thus, the organisms, their presence,
parts, interaction, and wastes all act as
biotic factors.
 These interactions include:
1. Nutritional relationships
2. Symbiotic relationships
Requirements for a Stable
Ecosystem

The ecosystem involves interactions
between living and nonliving things.
Certain requirements must be met for a
stable ecosystem to exist:
1. There must be a constant supply of energy
(sunlight for photosynthesis).
2. There must be living organisms that can
incorporate the energy into organic
compounds (food).
3. There must be a recycling of materials
between organisms and the environment.
Limiting Factors


Determines the types of organisms which
may exist in that environment.
Examples are:
1. A low temperature common to northern
latitudes determines in part what species of
plants can exist in that area.
2. The amount of oxygen dissolved in a body of
water will help determine which species of
fish will exist there.
Landscape
A spatially heterogeneous region that
includes several interacting
ecosystems
 Connections among ecosystems found
in a particular area.

Biosphere
 The
portion of the earth in
which life exists.
 The biosphere is composed
of many complex
ecosystems that include
water, soil, and air.
Ecological Organization
Population (
or
Community (
Ecosystem
Biosphere (
)
+
+
(
)
)
)
Do Now:

Compare and contrast potential energy
and kinetic energy using biological or
ecological examples and references
Types of energy

Energy: the capacity
or ability to do work.

Potential Energy:
Stored energy.

Kinetic Energy: The
energy of motion.
Do Now:

Define energy and briefly describe how
the different forms contribute to the
continual energy needs of organisms
Types of energy

Heat Energy: thermal energy that flows from an
object with a high temp. (heat source) to an
object with a lower temp. (heat sink).
 Nuclear
Energy: energy found within
atomic nuclei.
Types of Energy
 Electrical
Energy: energy that
flows as charged particles.
Thermodynamics: The study of energy
& its transformations.
1st Law of Thermodynamics: energy
cannot be created nor destroyed, but
it can be transformed.
2nd Law of Thermodynamics: when
energy is converted some usable
energy is degraded into a less usable
form. (Entropy)
Do Now:

Cellular respiration occurs in both plant
and animal cells while photosynthesis
only occur in plant cells. How are
plant and animals connected via these
two processes? Be sure to include
balanced chemical equations as part
of your answer.
Closed and Open
Systems
Earth is an open system because it receives
energy from the sun.
Types of Energy
Chemical Energy
Potential Energy
Mechanical (Kinetic) Energy
Radiant (Solar)
Heat Energy
Nuclear Energy
Electrical Energy
Energy Flow Relationships
 For
an ecosystem to be selfsustaining, there must be a flow of
energy between organisms.
 The pathway of energy flow through
the living components of an
ecosystem are represented by food
chains and food webs.
Nutritional
Relationships
 Involves
the transfer of nutrients from
one organism to another within an
ecosystem.
 In terms of nutrition, organisms are
either autotrophs or heterotrophs

SEE OWL LAB
Energy Flow through a
food Chain

Energy
Losses
The mouse receives energy from the food it eats.

Cells extract the food's energy for growth, acquiring
food, escaping enemies lost as heat. Some lost in the
mouse's waste (feces).

The remaining energy is stored in the mouse's body
and is available to the organism that preys on it.

About 90% of the energy is used or lost, only 10% is
available to predators.
Energy Flow
Biological Magnification


A nondegradable or slowly degradable
substance
That becomes more and more concentrated
in the tissues of organisms at higher trophic
levels of a food web.
– * Dichloro-Diphenyl-Trichloroethane (DDT)
– * Polychlorinated biphenyls (PCBs)
DDT in Food Webs
DDT
PCBs in Food Webs

PCB concentrations in animal
tissue can be magnified up to 25
million times.

Microscopic organisms pick up
chemicals from sediments

Consumed in large numbers by
filter feeding zooplankton.

Mysid shrimp then consume
zooplankton

fish eat the mysid

and so on up the food web to
the herring gull.

(Figure and caption from Our
Stolen Future, p. 27)
DDT Detection

In 1962, Rachel Carson,
a former U.S. Fish and
Wildlife Service (USFWS)
scientist and writer,
published Silent Spring,
outlining the dangers of
DDT
Fig. 41-8, p.736
Do Now:
Discuss the contributions of
saprotrophs and detritivores to a
balanced ecosystem.
 Identify two representatives of each
group in your discussion

(A)


Food Chains
Green plants and other
photosynthetic organisms
are the organisms in an
ecosystem that can
convert radiant energy
from sunlight into food.
A food chain involves the
transfer of energy from
green plants through a
series of organisms with
repeated stages of eating
and being eaten.
Food Chain
(B)



Food Webs
In a natural community, most organisms eat
more than one species and may be eaten, in
turn, by more than one species.
Thus, the various food chains in a community
are interconnected forming a food web.
SEE OWL LAB
Food Web at the Edge of an
Eastern Deciduous Forest
Do Now:
Define and discuss three applications of
the term: ecological pyramid.
 What accounts for the shape of the
pyramid?
 Use sketches of each type of pyramid
with associated quantitative units to
support your comparison.

(C) Pyramid of
Energy



The greatest amount of
energy in a community is
present in the organisms
that make up the producer
level.
Only a small portion of this
energy (10%) is passed on
to primary consumers, and
only a smaller portion (10%
of the original 10%) is
passed on to secondary
consumers.
A pyramid of energy can be
used to illustrate the loss of
usable energy at each
feeding level.
B. ALL living organisms must
carry out ALL 8 life functions
Nutrition
Synthesis
Transport
Growth
Respiration
Regulation
Excretion
Reproduction
Autotroph
 An
organism capable of
making their own food
–Photosynthetic
–Chemosynthetic
Chemosynthesis
A
type of autotrophic nutrition
 Does not require light as an energy
source
 Energy is obtained by chemical
reactions within the cell
 Example: Hydrothermal vent bacteria
Photosynthesis
 The
most common type of
autotrophic nutrition
 In this process, organisms
use energy from sunlight,
carbon dioxide, and water to
make food (usually glucose)
Chloroplast
 Contains
pigments called:
– chlorophylls (a & b greens)
– Xanthophylls (yellow)
– Carotenes (orange)
 It
is in the chloroplast that light
energy is trapped by chlorophylls and
glucose is formed as the product.
(food)
Structure of
Chloroplast
Wavelengths effects on
Photosynthesis

Which Wavelengths are
the best for
photosynthetic plants?
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b

Chlorophyll a
Which Wavelength is the
worst?
V
B
G
YO
R
http://seawifs.gsfc.nasa.gov/SEAWIFS.html
ROY G BIV
 The
maximum amount of
photosynthesis will occur when
exposed to red and blue light because
it is these two colors that are easily
absorbed in great quantity by the
chlorophyll
 For green leaves, green light is
reflected and therefore has the least
affect on photosynthesis
Formula for
Photosynthesis
6CO2 + 12H2O + radiant energy  C6H12O6 + 6H2O + 6O2
Formula for Cellular Respiration
C6H12O6 + 6O2 + 6H2O  6CO2 + 12H2O + work energy
Photosynthesis and
Cellular Respiration
Photosynthesis occurs in
two stages:
1.
Light Reaction
2.
Dark Reaction
Structure of
Chloroplast
Light reactions
Dark reactions
Photosynthesis: An Overview
Section 8-3
6CO2 + 12H2O + radiant energy  C6H12O6 + 6H2O + 6O2
Sunlight
water
CO2
Chloroplast
NADP+
ADP + P
LightDependent
Reactions
Calvin
Cycle
ATP
NADPH
O2
Sugars
1. Light Reaction
1.
2.
3.
4.
5.
6.
Occurs in the grana of the chloroplast.
First stage of photosynthesis.
Begins with the absorption of light energy
by chlorophyll.
Photolysis occurs- a reaction in which H2O
molecules split into oxygen and hydrogen.
All oxygen given off during photosynthesis
comes from the photolysis of water.
ATP (Adenosine triphosphate), which is a
form of chemical energy, is produced.
Light Reaction
Oxygen
(6O2)
Chloroplast
I am out
of here!
12 WATER
molecules
(H2O)
12 Hydrogen 12 Hydrogen
AKA
Photolysis
NADPH
+ ATP
(This all occurs
In the Grana.)
Dark
Reaction
“Calvin Cycle”
“Light
Independent
Reaction”
(This all occurs
in the Stroma.)
NADPH
+ATP
12 Hydrogen 12 Hydrogen
Carbon Fixation
6(CO2)
C6H1206
AKA
Glucose
6(H20)
The Food Factory
2. Dark Reaction





Occurs in the stroma of the chloroplast.
The second stage of photosynthesis.
It is here that CO2 is converted to carbohydrates
by a process called carbon fixation.
CO2  PGAL  C6H12O6
Light is not required.
The dark reaction requires ATP from the light
reaction for it to take place.
Factors Affecting the Rate
of Photosynthesis
1.
2.
3.
4.
Light Intensity
Water
Carbon dioxide level
Temperature
Adaptations for
Photosynthesis
A. Unicellular Organisms
1. Almost all chlorophyll-containing
unicellular organisms are aquatic. (live in
water)
2. The raw materials for photosynthesis
are absorbed directly from the water and
into the cell
Ex: algae &
cyanobacteria
Adaptations for
Photosynthesis
B. Terrestrial Plants (land-dwelling)
1. Occurs in leaves that provide the
maximum surface area for the absorption of
light.
Plants
 Leaves-
 Stems-
have stomates for gas
exchange
have lenticels for gas exchange
– Roots- gas exchange occurs
across a moist membrane
of root hairs (diffusion)
Do Now:

Briefly explain the process of cellular
respiration and uses of the energy
obtained from the process. Your
answer should include the following
terms: glucose, water, carbon dioxide,
chemical energy, and oxygen. What
organisms carry on this process?
Glycolysis (splitting glucose)
2 ATP
Glucose
2 PGAL
(C6H12O6)
(C3H5O3)
2 pyruvic acid
+4 ATP
Net Gain:???
Glycolysis (splitting glucose)

Net Energy Yield from Glycolysis

Energy requiring steps:
– 2 ATP invested

Energy releasing steps:
– 2 NADH formed
– 4 ATP formed

Net yield is 2 ATP and 2 NADH
Glycolysis (splitting glucose)
All three reactions with
Glycolysis
Glycolysis occurs in cytoplasm
 Reactions are catalyzed by enzymes

Glucose
(six carbons)
2 Pyruvate
(three carbons)
Equations for Anaerobic Respiration
1. Lactic Acid Fermentation
glucose  2 lactic acids + 2 ATP’s
2. Alcoholic Fermentation
glucose  2 alcohol + 2 CO2 + 2 ATP’s
In each equation, enzymes are used and a net
gain of 2 ATP’s are produced
Aerobic Respiration
Glucose + O2  H2O + CO2 + 36 ATP’s
 Again, enzymes are used and a net of 36
ATP’s are produced
Equations for
Anaerobic
Respiration
glucose
 2 lactic acids + 2 ATP’s
glucose  2 alcohol + 2 CO2 + 2
ATP’s

In each equation, enzymes are used
and a net gain of 2 ATP’s are produced
Aerobic
Respiration
glucose + O2  H2O + CO2 + 36
ATP’s
•Again, enzymes are used and a
net of 36 ATP’s are produced
Who am I?
Do Now:

What is the human impact on net
primary productivity? What are the
potential environmental problems
associated with this impact and what
changes would be required to
minimize human impact?
(NPP)
=
Gross Primary Productivity
(GPP) (total energy from
photosynthesis /unit
area/time)
- Plant respiration (energy
invested by plants)
(NPP) = GPP (rate) – Plant Respiration
Total energy produced
Energy cost
Humans compete with other species
for energy.
Our planet cannot handle
the burden from human overpopulation.
Table 9l-1: Average annual Net Primary
Productivity of the Earth's major biomes.
Ecosystem Type
Net Primary Productivity
(kilocalories/meter 2 /year)
Tropical Rain Forest
Estuary
Swamps and Marshes
9000
9000
9000
Boreal Forest
Temperate Grassland
3500
2000
Polar Tundra
Desert
600
< 200
Humans compete with other species
for energy. Our planet cannot handle
Savanna
3000
human
overpopulation.
Deciduous Temperate Forest
6000
http://www.physicalgeography.net/fundamentals/9l.html
There are 3 basic organisms in a
food web:
1)Producers
2)Consumers
2a) Primary consumers
2b)Secondary consumers
3)Decomposers
There are 3 basic organisms in a
food web:
1.
Producers- include green plants and other
photosynthetic organisms that synthesize
the organic nutrients that supply energy to
other members in the community.
Question

Briefly discuss the role of autotrophs in
an ecosystem
http://www.dnr.state.wi.us/org/water/fhp/lakes/under/oxygen.htm
There are 3 basic organisms in a
food web:
1.
Consumers- include all heterotrophic
organisms. Organisms that feed on green
plants are primary consumers, or
herbivores. Secondary consumers, or
carnivores, feed on other consumers.
Omnivores eat producers and consumers.
There are three basic classes of
organisms in a food web:
Decomposers – are the organisms
(saprotrophs) that break down wastes and
dead organisms so that chemical materials
are returned to the environment for use by
other living organisms.
Antarctic food web
Antarctic food web
Krill!
Do Now:

What are krill? Using appropriate
terminology, discuss the role of krill in
the Antarctic food web, and describe
what has been happening to the
population of these animals over that
past 150 years and why. What has
been the impact on this Antarctic
ecosystem of human related change in
the global environment?
Do Now:

Today, commercial fishermen are
“fishing down the food web.” This is
unsustainable. WHY? How can this
movement down the marine food web
be reversed?
D-End