2. o Ecology o Potential vs. Kinetic energy
o Species o 1st law of thermodynamics
o Population o 2nd law of thermodynamics
o Community o Photosynthesis
o Ecosystem o Cellular Respiration
o Atomosphere o Chemosynthesis
o Lithosphere o How energy flows through an
o Hydrosphere ecosystem
o Heterotrophs o Producers
o Omnivores o Consumers (primary, secondary,
o Detritus tertiary)
o Trophic levels o Decomposers/Saprotrophs
o Gross primary productivityo Ecological pyramid (numbers,
(GPP) biomass, energy)
o Net primary productivity
(NPP)
3. Overview of Chapter 3
o Ecology
o Energy
• First Law of Thermodynamics
• Second Law of Thermodynamics
o Photosynthesis and Cellular Respiration
o Flow of Energy Through Ecosystems
• Producers, Consumers & Decomposers
• Ecological Pyramid
• Ecosystem Productivity
4. o Ecology
Ecology
• “eco” house & “logy” study of
• The study of interactions among and between
organisms in their abiotic environment
• Broadest field in biology
o Biotic-
• living environment
• Includes all organisms
o Abiotic-
• non living or physical environment
• Includes living
space, sunlight, soil, precipitation, etc.
5. Ecology
o Biology is
very
organized
o Ecologists
are
interested
in the levels
of life
above that
of organism
6. Ecology Definitions
o Species
• A group of similar organisms whose members freely
interbreed
o Population
• A group of organisms of the same species that occupy
that live in the same area at the same time
o Community
• Al the populations of different species that live and
interact in the same area at the same time
o Ecosystem
• A community and its physical (abiotic) environment
o Landscape
• Several interacting ecosystems
7. Ecology
o Biosphere contains earth’s
communities, ecosystems and
landscapes, and includes:
• Atmosphere-
gaseous envelope
surrounding earth
• Hydrosphere-
earth’s supply of
water
• Lithosphere- soil
and rock of the
earth’s crust
8. Energy
o The ability or
capacity to do work
• Chemical, radiant,
thermal, mechanical,
nuclear, electrical
o Energy exists as:
• Stored energy
(potential energy)
• Kinetic energy (energy
of motion)
9. Thermodynamics
o Study of energy and its transformations
o System- the object being studied
• Closed System- Does
not exchange energy
with surroundings (rare
in nature)
• Open System-
exchanges energy with
surroundings
10. Laws of Thermodynamics
o First Law of Thermodynamics
• Energy cannot be created or destroyed; it can
change from one form to another
• Ex: organisms cannot create energy they need to
survive- they must capture it from another source
• Focus is on quantity
o Second Law of Thermodynamics
• When energy is converted form one form to
another, some of it is degraded to heat
• Heat is highly entropic (disorganized)
• Focus is on quality
11. Photosynthesis
o Biological process by which energy from
the sun (radiant energy) is transformed
into chemical energy of sugar molecules
6 CO2 + 12 H2O + radiant energy
C6H12O6 + 6 H2O + 6 O2
o Energy captured by plants via
photosynthesis is transferred to the
organisms that eat the plants
12. Cellular Respiration
o The process where the chemical energy
captured in photosynthesis is released
within cells of plants and animals
C6H12O6 + 6 O2 + 6 H2O
6 CO2 + 12 H2O + energy
o This energy is then used for biological
work
• Creating new cells, reproduction, movement,
etc.
13. Energy Flow
o Passage of energy
in a one-way
direction through
an ecosystem
• Producers
• Primary consumers
• Secondary
consumers
• Decomposers
14. Food Chains- The Path of Energy Flow
o Energy from food passes from one
organisms to another
• Each “link” is called a trophic level
15. Food webs represent interlocking food chains
that connect all organisms in an ecosystem
16. Ecological Pyramids
o Graphically represent the relative energy
value of each trophic level
• Important feature is that large amount of
energy are lost between trophic levels to heat
o Three main types
• Pyramid of numbers
• Pyramid of biomass
• Pyramid of energy
17. Pyramid of Numbers
o Illustrates the number of organisms at each
trophic level
• Usually, organisms at the base of the pyramid
are more numerous
• Fewer organisms occupy
each successive level
o Do not indicate the
biomass of the
organisms at each level
or the amount of
energy transferred
between levels
18. Pyramid of Biomass
o Illustrates the total biomass at each
successive trophic level
• Biomass: measure of the total amt of living
material
• Biomass indicates the
amount of fixed energy
at a given time
o Illustrates a
progressive reduction
in biomass through
trophic levels
19. Pyramid of Energy
o Illustrates how much energy is present at
each trophic level and how much is
transferred to the next level
• Most energy dissipates between trophic levels
o Explains why there
are so few trophic
levels
• Energy levels get too
low to support life
20. Ecosystem Productivity
o Gross Primary Productivity (GPP)
• Total amount of energy that plants capture and
assimilate in a given period of time
o Net Primary Productivity (NPP)
• Plant growth per unit area per time
• Represents the rate at which organic material
is actually incorporated into the plant tissue
for growth
o GPP – cellular respiration = NPP
• Only NPP is available as food to organisms
22. Human Impact on NPP
o Humans consume more of earth’s resources
that any other animal
• Humans represent 0.5% of land-based biomass
• Humans use 32% of land-based NPP!
o This may contribute to loss of species
(extinction)
o Humans’ high consumption represents a
threat to planet’s ability to support both
human and non-human inhabitants
