Download Chapter 4: Ecosystems: Components, Energy Flow, Matter Cycling

Chapter 4: Ecosystems: Components,
Energy Flow, Matter Cycling
EQ’s: What language (vocabulary) is used
by ecologists to classify the various
aspects of the ecosystems they study?
4-1 The Nature of Ecology
Definitions:
Ecology is the study of how organisms
(biotic) interact with each other and their
environment (abiotic).
Abiotic factors include: sunlight,
temperature, precipitation, wind, fire, soil,
etc.).
Organisms are individual living things.
Organisms that reproduce with each other
under natural conditions are called species.
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Eukaryotic organisms have a membrane
bound nucleus and complex organelles.
Almost all organisms have eukaryotic cells.
Prokaryotic: no distinct nucleus and lack
most organelles (bacteria and the bluegreen algae.
Asexual reproduction: no exchange of
genetic information and therefore little
genetic variation.
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Sexual reproduction: combine sex cells to
exchange genetic information and create
genetic diversity in the offspring.
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A population consists of all the individuals
of the same species that occupy a specific
area of the environment (habitat).
A community consists of all the interacting
populations in a given location.
All the communities interacting
communities along with the abiotic
components in a given area constitute an
ecosystem and all the ecosystems together
make up the biosphere (see Fig:4.2; page
66).
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4-2 Earth’s Life-Support Systems
EQ’s: 1- How do tolerances levels and
limiting factors help structure
ecosystems?
The Earth has several layers or spheres
upon which life depends:
Atmosphere: layer of air
Hydrosphere: layer of water
Lithosphere: layer of rock
Biosphere: layer of life
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High quality energy flows through the
Earth’s systems from the sun. Matter,
however, is recycled by living things.
Photosynthesis is the process by which
plants capture solar energy and use it to
transform water and carbon dioxide into a
carbohydrates.
light
6CO2 + 6H2O --------------- C6H12O6 + 6O2
The sun’s energy also powers the cycling
of matter that drives climate and weather
systems across the planet.
Assignment #1: Review Questions page 93; #’s 2, 3, 4, 5,
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4-3 Ecosystem Concepts and
Components
The terrestrial (land) portion of the
biosphere is divided into different biomes
based upon climate and the forms of life
adapted to it. Examples include: rain
forests, deserts, deciduous forests,
grasslands, tundra, etc.
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The aquatic ecosystems are divided into
freshwater (ponds, lakes, streams) and
marine (coral reefs, coastlines, oceans,
estuaries).
Climate refers to the long-term weather
patterns that influence the type of life that
lives in an area.
In reality ecosystems/biomes rarely have
distinct boundaries and are rarely selfsustaining. Ecosystems merge in transition
zones known as ecotones.
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Living things are distributed within
ecosystems based upon the law of
tolerance. Each population has a range of
conditions (both physical and chemical) it
can withstand (See Fig:4-14; page: 73).
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For a population to exist within an
ecosystem the physical and chemical
conditions must fall within that species’
range of tolerance.
Often one factor (limiting factor) tends
to be the most important in determining the
size of a population within an ecosystem.
Assignment #2: Review Questions: 8, 9, 10, 11 (all parts)
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4-4: Energy Flow in Ecosystems
EQ: 1- How does the flow of energy
contribute to the structure of
ecosystems?
Energy flows through an ecosystem only
in one-way. The sequence of organisms
through which energy flows is called a food
chain.
What information do food chains fail to
convey? (2 things).
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Food webs show a more realistic view of
energy flow because organisms typically do
not feed on a single species (Fig. 4-19).
Living organisms are classified as either
producers (autotrophs) capable of making
their own food and consumers
(heterotrophs) that cannot.
Heterotrophs are further classified as
herbivores (plant eaters), carnivores (meat
eaters), omnivores (eat both), scavengers
(feed on dead organisms), and decomposers
(fungi and bacteria).
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Both autotrophs and heterotrophs
breakdown the carbohydrates produced
during photosynthesis in a process known
as aerobic respiration.
C6H12O6+6O2---6CO2+6H2O+energy (ATP)
As energy flows through an ecosystem
much of it is lost. Most ecosystems have an
ecological efficiency of 10%--20%.
This loss of energy between trophic
(feeding) levels is often illustrated using a
pyramid of energy (See Figs. 4-20; 4-21).
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As a result of this loss of energy most
energy pyramids are limited to 5 or 6
trophic levels.
Use the information provided in Figure 4-21
to perform the following calculations.
How much of the Sun’s energy do the
producers capture? _______ kcal
1. What percentage of that is transferred to
the herbivore level (energy efficiency)?
Energy out X 100
Energy In
2. What percentage is lost as metabolic
heat?
3. What percentage of what the herbivores
capture is passed on to the carnivores?
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4. Of the original amount of heat captured
by the producers (20,810 kcal) what
percentage is passed on to the top
carnivores?
5. So why are there typically so few top
predators in a given ecosystem?
Biodiversity (a renewable resource)
measures the different forms of life and lifesustaining processes found in ecosystems.
There are several types:
Genetic diversity: genetic make-up
Species diversity: number of different
species in a given habitat
Ecological diversity: diversity of biological
communities
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Functional diversity: diversity of biological
and chemical processes needed for
survival.
4-5 Primary Productivity
The rate an ecosystem’s primary
producers convert solar energy into biomass
is called gross primary productivity (GPP).
Some of this biomass is used to stay
alive, grow, and reproduce (etc.). What
remains is called net primary productivity
(NPP). The NPP ultimately limits the
number of consumers in a given ecosystem.
It has been estimated that humans use or
waste approximately 27% of the planet’s
total NPP.
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See Figure 4-25 to answer the following
questions
1. What three ecosystems have the greatest
NPP?
2. How many times greater is the NPP of
a rain forest compared to a temperate
Grassland?
A temperate forest compared to a
savanna?
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Agricultural land compared to the open
ocean?
Estuaries compared to extreme desert?
4-7 How Do Ecologist’s Learn About
Ecosystems
EQ: What advantages and disadvantages
are associated with the methods
scientists use to study ecosystems?
Field Research involves going into
nature to observe and measure what is
going on in ecosystems. Disadvantages
include cost (travel, food, etc.) and the
difficulty associated with trying to control
variables.
Laboratory research uses models that
allow greater control of variables. The
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major disadvantage is knowing if the model
behaves like the real thing.
Systems analysis involves the use of
complex mathematical models and
computer simulations to mimic the natural
world. Today most ecological research is
done using a combination of all three
approaches.
Assignment #3 Review Questions: 12, 13 (all terms), 14, 17.
Textbook Review Assignment
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