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Environmental Science Ch. 3: How Ecosystems Work

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Title: Environmental Science Ch. 3: How Ecosystems Work


1
Environmental Science Ch. 3How Ecosystems Work
2
Ch. 3-1 Energy Flow In Ecosystems
  • Key Terms
  • Cellular Respiration
  • Consumer
  • Decomposer
  • Food Web
  • Producer
  • Trophic Level

3
California Content Standards for Science
Addressed
  • Life Science
  • 6(d) Students know how water, carbon, and
    nitrogen cycle between abiotic resources and
    organic matter in the ecosystem and how oxygen
    cycles through photosynthesis and respiration.
  • 6(e)Students know a vital part of an ecosystem is
    the stability of its producers and decomposers.
  • 6(f)Students know at each link in a food web
    some energy is stored in newly made structures
    but much energy is dissipated into the
    environment as heat. This dissipation may be
    represented in an energy pyramid.

4
Ch. 3 Section 1Why Do I Need To Know This?
  • Because what you are depends upon what you eat .
    . . so we need to know what were eating and what
    that stuff is eating.
  • Because we are removing major amounts of
    organisms from various levels in ecosystems and
    causing serious disruption to food webs and food
    chains.
  • Because we can increase food production to feed
    more people without using toxic pesticides by
    understanding the importance of each and every
    trophic level in an ecosystem.

5
Key Sections Ch. 3-1
  • Energy Flow In Ecosystems
  • Life Depends on the Sun
  • An Exception in the Rule Deep-Ocean Ecosystems
  • What Eats What
  • Respiration Burning The Fuel
  • Energy Transfers Food Chains, Food Webs, and
    Trophic Levels
  • Food Chains and Food Webs
  • Trophic Levels
  • How Energy Loss Affects An Ecosystem

6
Energy Flow In Ecosystems
  • All organisms need energy in order to survive.
  • To fully understand an organism and its
    ecosystem, we need to understand how it gets its
    energy and how the energy flows in the ecosystem.

7
Life Depends on the Sun
  • Almost all life depends either directly or
    indirectly for energy from the sun.
  • Plants, algae and some bacteria can turn solar
    energy directly into energy through a process
    called photosynthesis. These organisms are
    called producers.
  • When animals eat plants or other animals that ate
    plants, they are still getting their energy
    indirectly from the sun. These organisms are
    consumers.

8
An Exception To the Rule Deep-Ocean Ecosystems
  • There is one known exception to the rule about
    all life depending on the sun, and that is at the
    very bottom of the deep ocean.
  • In 1977, scientists discovered that existed so
    deep that no sunlight could reach them.
  • The scientists discovered that the plants and
    animals got their energy from volcanoes erupting
    underneath the ocean!
  • They called this type of life chemosynthesis.

9
What Eats What
  • Consumers that only eat producers are called
    herbivores.
  • Consumers that only eat other consumers are
    called carnivores.
  • Consumers that eat both producers and other
    consumers are called omnivores.
  • Consumers that get their nutrients by eating the
    dead remains of other organisms are called
    decomposers.

10
Respiration Burning The Fuel
  • Photosynthesis is the chemical reaction used by
    producers to make food.
  • The chemical reaction is 6CO2 6 H20 Light
    Energy ? C6H12O6 6O2
  • Respiration is the process that consumers use to
    produce energy from the food they eat.
  • The chemical reaction is C6H12O6 6O2 ? 6CO2
  • 6H20 Energy
  • They are opposite reactions!

11
Energy Transfers Food Chains, Food Webs, and
Trophic Levels
  • Every time one organism eats another organism,
    energy is transferred in an ecosystem.
  • Ecologists trace the transfer of energy in two
    ways
  • Food Chains These show the direct line of how
    the energy is transferred from one organism to
    another.
  • Food Webs These show the many feeding
    relationships between organisms in an ecosystem.

12
Food Chains and Food Webs
  • Food chains are especially useful in showing
    direct cause and effect relationships in an
    ecosystem.
  • Food webs are useful in representing how an
    ecosystem truly works because most consumers
    usually eat more than one organism.

13
Trophic Levels
  • Each level of energy transfer in an ecosystem is
    known as a trophic level.
  • As energy moves up each trophic level, about 90
    of the energy is lost, leaving only about 10 of
    the energy available for the next level.
  • Therefore, the lowest trophic levels contain the
    largest population sizes and the highest trophic
    levels have the smallest population sizes.
  • Energy is lost in each trophic level because all
    the life functions for the organisms at that
    level (such as growing, moving, reproducing,
    etc.).

14
How Energy Loss Affects And Ecosystem
  • When the amount of energy available at a lower
    level decreases, the amount of organisms that can
    be sustained at a higher trophic level also
    decreases and the number of trophic levels that
    can exist also decreases.
  • Humans are at the top of all trophic levels.
  • So, if we wipe out many lower tropic levels, we
    will reduce the number of people that can live on
    the planet and can wipe out many species that
    live at lower trophic levels.

15
Ch. 3-2 The Cycling of Materials
  • Key Terms
  • Precipitation
  • Water Cycle

16
California Content Standards for Science
Addressed
  • Life Science
  • 6(d) Students know how water, carbon, and
    nitrogen cycle between abiotic resources and
    organic matter in the ecosystem and how oxygen
    cycles through photosynthesis and respiration.

17
Ch. 3 Section 2Why Do I Need To Know This?
  • Because every atom of every cell in your body has
    most likely been a part of another organism.
  • Because every atom of every molecule of food that
    you eat or drink has probably been eaten, drunk,
    or used by another living organism.
  • Because as long as the materials recycle, an
    ecosystem will stay in balance. When it no
    longer cycles from organism to organism, the
    ecosystem will collapse and die out.

18
Key Sections Ch. 3-2
  • The Cycling of Materials
  • The Water Cycle
  • The Carbon Cycle
  • How Humans Are Affecting the Carbon Cycle
  • The Nitrogen Cycle
  • Closing the Nitrogen Cycle

19
The Cycling of Materials
  • In every ecosystem, all materials get recycled.
  • All materials get recycled at various rates.
  • Some are very fast, while others can take
    millions of years.
  • Without the recycling of materials, all
    ecosystems would collapse when they ran out of
    limited resources.
  • There are many cycles in nature, but 3 of the
    most important are
  • The Water Cycle
  • The Carbon Cycle
  • The Nitrogen Cycle

20
The Water Cycle
  • Water is essential for all life.
  • Although water changes form (from a solid to
    liquid to gas), the overall amount of water
    remains the same on the Earth.
  • The 3 main steps to the water cycle are
  • Evaporation
  • Condensation
  • Precipitation
  • The overall force driving the water cycle is the
    energy from the sun.
  • Water can be removed from the water cycle and
    stored underground as groundwater.

21
The Water Cycle
22
The Carbon Cycle
  • Carbon is also essential for all life on Earth.
  • Carbon is used to make up proteins, fats, and
    carbohydrates (all of which we need everyday).
  • When consumers eat producers, they take in the
    carbon they need.
  • During respiration, consumers give back carbon
    into the environment.
  • Some carbon gets stored underground as the
    remains of plants and animals get buried. This
    carbon will go onto become fossil fuels.

23
The Carbon Cycle
24
How Humans Are Affecting The Carbon Cycle
  • Fossil fuels, such as coal, oil and gasoline
    contain large amounts of carbon that has been
    stored underground.
  • As humans burn fossil fuels, we are emitting
    large amounts of carbon dioxide into the
    ecosystem, which is having a major effect on the
    worlds atmosphere and climate.

25
The Nitrogen Cycle
  • Nitrogen is another essential element for life.
  • Nitrogen is used to make proteins, which is
    necessary for life.
  • Although 78 of the atmosphere is Nitrogen, only
    a special type of Nitrogen called Nitrates (NO3)
    can be used by most life forms on the planet.
  • In order to get Nitrogen, most bacteria depend
    upon bacteria to fix the Nitrogen in the
    atmosphere to make it useable at Nitrates.
  • The bacteria that fix the Nitrogen are called
    Nitrogen-fixing bacteria.

26
Closing the Nitrogen Cycle
  • Once Nitrogen enters into the ecosystem through
    the nitrogen fixing bacteria, it mostly stays
    there.
  • Nitrogen in an ecosystem gets broken down by
    decomposers, such as fungi and bacteria.
  • However, some Nitrogen is returned to the
    atmosphere by different bacteria.

27
The Nitrogen Cycle
28
Ch. 3-3 How Ecosystems Change
  • Key Terms
  • Climax Community
  • Pioneers
  • Succession

29
California Content Standards for Science
Addressed
  • Life Science
  • 6(a) Students know biodiversity is the sum total
    of different kinds of organisms and is affected
    by alterations of habitats.
  • 6(b) Students know how to analyze changes in an
    ecosystem resulting from changes in climate,
    human activity, introduction of nonnative
    species, or changes in population size.
  • 6(e) Students know a vital part of an ecosystem
    is the stability of its producers and
    decomposers.

30
Ch. 3 Section 3Why Do I Need To Know This?
  • Because all ecosystems change over time.
  • So that we can understand the role of each
    organism in its ecosystem to know how it is
    helping the ecosystem change.
  • So that we can better respond to natural
    disasters and environmental problems by using
    succession to help fix the problem and restore a
    damaged ecosystem.

31
Key Sections Ch. 3-3
  • How Ecosystems Change
  • Succession
  • Secondary Succession
  • Fire-Maintained Communities
  • Primary Succession

32
How Ecosystems Change
  • All ecosystems change over time.
  • Over time, areas will change from a rocky
    landscape to a very well developed and stable
    community.

33
Succession
  • Succession is the regular pattern of change in
    the species in a community.
  • Succession happens because as one species enters
    into an ecosystem, it alters the ecosystem to
    suit it.
  • As the species change the ecosystem, they make it
    more difficult for some organisms to live in the
    ecosystem and easier for others to live in it.
  • Eventually, an ecosystem reaches a stable and
    final community. This is called a climax
    community.

34
Secondary Succession
  • Secondary succession occurs when a new community
    develops on the spot of a previously existing
    community.
  • This typically happens after a major natural
    disaster (such as a fire) or after an area has
    been cleared for human use.
  • Secondary succession happens rather rapidly
    (within about 150 years) because the soil and
    many of the necessary nutrients are already in
    place.
  • During secondary succession, grasses and flowers
    recover first. Then, over time, shrubs and trees
    move in, and finally trees take over, crowding
    out the plants and shrubs.

35
Secondary Succession
36
Fire-Maintained Communities
  • Many ecosystems depend upon natural fires to
    maintain themselves.
  • Some species, pine trees, for example, require
    the heat from a fire to release their seeds.
  • Many animals depend on natural fires to open up
    space for grasses and other producers to grow in
    order to feed upon them.
  • Fire helps to eliminate new species to the
    ecosystem to help maintain the stability of that
    ecosystem.
  • As a result, in some areas, firefighters allow
    naturally occurring fires to burn themselves out.

37
Primary Succession
  • Primary succession occurs on surfaces where no
    previous ecosystem existed.
  • This is much slower process than secondary
    succession, typically taking thousands of years
    to happen.
  • The first organisms to move into the new area are
    called pioneers. Bacteria and lichens are two
    common pioneers.
  • The pioneers play an important role in succession
    because they turn raw material into useable
    resources for all species that follow them.
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