1. Chapter 42
Ecosystems

2. 42.1 How Do Energy and Nutrients Move Through An Ecosystem?
Ecosystems
A ____________ of organisms together with the nonliving components of their environment
Organisms and their environment interact through a __________ flow of _________ and a _______________________.
Nutrients taken up by ____________ are returned to the environment by ________________, then taken up again

3. How Do Energy and Nutrients Move Through An Ecosystem? (cont’d.)
An ecosystem runs on energy captured by ______________________
Primary producer (_____________)
An organism that obtains energy and nutrients from _____________________ to build organic compounds
Primary production
Rate at which producers capture and store energy
Varies by ecosystem, season, and ______________________

4. How Do Energy and Nutrients Move Through An Ecosystem? (cont’d.)
Consumers are described by their diets
Herbivores (_____________)
Carnivores (___________________)
Parasites (__________________________)
Omnivores (_________________________)
Detritivores (_________________)
Decomposers (______________________)

5. ANIMATION: One-way energy flow and materials cycling
Figure 42.1 {Animated}
One-way flow of energy (yellow arrows) and nutrient cycling (blue arrows) in the most common type of ecosystem. All light energy that enters the system eventually returns to the environment as heat energy that is not reused. By contrast, nutrients are continually recycled.
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6. How Do Energy and Nutrients Move Through An Ecosystem? (cont’d.)
Food chains
Describe how energy and materials are ___________ from one organism to another
Description of __________________ in one _____________________ in an ecosystem
Transfer of energy to _________________ levels
Trophic level: ______________ of an ________________ in a food chain

7. How Do Energy and Nutrients Move Through An Ecosystem? (cont’d.)
Limits of food chains
Energy captured by producers usually passes through __________________ four or five trophic levels
The length of food chains is _____________ by the ________________ of energy transfers
Only 5-30% of energy in an organism at one trophic level ends up in _____________ of an organism at the next trophic level

8. 3D Animation: Food Chain
Figure 42.2 {Animated} Food chain. An example of who eats whom in a tall grass prairie ecosystem in Kansas. Yellow arrows indicate energy flow. Plants are the main producers. Sunlight energy they capture and store in their tissues supplies the energy that the ecosystem’s consumers require.

9. 42.2 How Do Food Chains Interconnect?
Food chains of an __________________ as a food web
The food web diagram reflects _________________ constraints and the inefficiency of energy transfers among trophic levels

10. ANIMATION: Rainforest food web
Figure 42.3 {Animated} Some organisms in an arctic food web. Yellow arrows indicate path of energy flow (point from eaten to eater).
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11. How Do Food Chains Interconnect (cont’d.)
Food webs include two types of interconnecting food chains
_______________ food chain
Energy transferred from producers to herbivores (______________)
Energy transferred directly from producers to detritivores (_______________________)
Major food chain in land ecosystems

12. 42.3 What Are Ecological Pyramids?
Ecological pyramid diagrams illustrate the inefficiency of transfers between trophic levels
A _____________________ shows amounts of ________________________in bodies of organisms at each trophic level at a specific time
An __________ pyramid shows energy flow through each trophic level in a given interval

13. What Are Ecological Pyramids? (cont’d.)
Figure 42.4 Computer model for a land food web in East River Valley, Colorado. Balls signify species. Their colors identify trophic levels, with producers (coded red) at the bottom and top predators ( yellow) at top. The connecting lines thicken as they go from an eaten species to the eater.

14. ANIMATION: Energy flow at Silver Springs
Figure 42.5 {Animated} Ecological pyramids for Silver Springs, an aquatic ecosystem in Florida.
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15. 42.4 Biogeochemical Cycles
___________ essential to life move between a ______________ and its environment in a biogeochemical cycle
A nutrient moves between environmental ______________ and in and out of food webs
Chemical and _____________ processes move elements to, from, and among environmental reservoirs (rocks, sediments, water, atmosphere)

16. Biogeochemical Cycles (cont’d.)
Figure 42.6 Generalized biogeochemical cycle. For any nutrient, the cumulative amount in all environmental reservoirs
far exceeds the amount in living organisms.

17. 42.5 What Is the Water Cycle?
Ninety-seven percent of Earth’s water is in its oceans
Sunlight energy drives the water cycle by causing ______________
Water vapor in the atmosphere _______________ into clouds, and returns to Earth’s surface as ______________

18. ANIMATION: Hydrologic cycle
Figure 42.7 {Animated} The water cycle. Water moves from the ocean to the atmosphere, land, and back. The
arrows identify processes that move water.
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19. What Is the Water Cycle? (cont’d.)
How water moves
Precipitation that falls on any specific area of land drains into its particular _____________
Most precipitation seeps into the ground (groundwater)
Water that drains through soil layers often collects in natural underground reservoirs (______________)
The flow of groundwater and surface water (___________) slowly returns water to oceans

20. What Is the Water Cycle? (cont’d.)
Table 42.1 Environmental water resources

21. 42.6 How Does Carbon Move Through Ecosystems?
Carbon cycle
An ______________ cycle
Most carbon is stored in rocks
Enters food webs as ___________ carbon dioxide or bicarbonate dissolved in water
Movement is mainly between the oceans, atmosphere, and living organisms

22. How Does Carbon Move Through Ecosystems? (cont’d.)
Steps in the carbon cycle
Carbon enters land food webs when plants use _______ from the air in photosynthesis
CO2 released by _________________ returns to the atmosphere
Carbon diffuses between ______________ and _____________
____________ forms when CO2 dissolves in seawater

23. How Does Carbon Move Through Ecosystems? (cont’d.)
___________ producers take up bicarbonate for photosynthesis; marine organisms release CO2 from aerobic respiration
Many marine organisms incorporate carbon into shells, which become part of sediments
Sediments become limestone and chalk in Earth’s crust
Burning ________________ derived from ancient remains of plants puts additional CO2 into the atmosphere

24. ANIMATION: Carbon cycle
Figure 42.8 {Animated} The carbon cycle
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25. How Does Carbon Move Through Ecosystems? (cont’d.)
Greenhouse effect
Warming of Earth’s lower atmosphere and surface as a result of heat _____________ by greenhouse gases

26. How Does Carbon Move Through Ecosystems? (cont’d.)
Earth’s atmosphere ____________ some sunlight energy back into space
Some light energy reaches and warms Earth’s surface
Earth’s warmed surface ____________ heat energy
Some __________________________
Some is _________________________ in all directions by greenhouse gases

27. How Does Carbon Move Through Ecosystems? (cont’d.)
_________________ increase in atmospheric greenhouse gases correlates with global climate change
Current atmospheric CO2 is the highest in 420,000 years–and is still climbing
Global climate change
A rise in temperature and shifts in other climate patterns

28. ANIMATION: The Greenhouse Effect
Figure 42.9 {Animated} The Greenhouse Effect
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29. 42.7 How Does Nitrogen Move Through Ecosystems?
Nitrogen cycle
An atmospheric cycle
Atmospheric nitrogen (________________) is Earth’s main nitrogen reservoir, but most organisms can’t use N2

30. 42.7 How Does Nitrogen Move Through Ecosystems?
Certain bacteria can make nitrogen available to other organisms/atmosphere
With nitrogen _____________, bacteria:
Use nitrogen gas (N2) to form ammonia (NH3)
With _______________, bacteria:
Convert ammonium (NH4+) to nitrates (NO3-)
With ________________, bacteria:
Convert nitrates or nitrites (NO2-) to nitrogen gas

31. How Does Nitrogen Move Through Ecosystems? (cont’d.)
Steps in the nitrogen cycle
Nitrogen-fixing __________________ in soil, water, or lichens break bonds in N2 and form ammonia, which is ______________ in water as ammonium (NH4+) and taken up by plants
Another group of nitrogen-fixing bacteria forms nodules on roots of peas and other legumes

32. How Does Nitrogen Move Through Ecosystems? (cont’d.)
____________ get nitrogen by eating plants or one another; bacterial and fungal decomposers ___________________ wastes and remains and return ammonium to the soil
Nitrification converts ammonium to nitrates:
_____________________ bacteria and ______________ convert ammonium to nitrite (NO2–)
_____________ convert nitrites to nitrates (NO3– )

33. How Does Nitrogen Move Through Ecosystems? (cont’d.)
Nitrates are taken up and used by producers
Denitrifying bacteria use nitrate for energy and _____________ nitrogen gas into the atmosphere

34. ANIMATION: Nitrogen cycle
Figure {Animated} The nitrogen cycle in a land ecosystem
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35. How Does Nitrogen Move Through Ecosystems? (cont’d.)
Manufactured ammonia fertilizers increase the concentration of H+ and N
Essential nutrients ___________ away in soil water
Nitrogen ___________ pollutes aquatic habitats
Burning fossil fuels releases nitrous oxide, a greenhouse gas contributing to acid rain
Nitrogen in acid rain has the same effects as fertilizers

36. How Does Nitrogen Move Through Ecosystems? (cont’d.)
Figure A tractor applying industrially produced, nitrogen-rich fertilizer to a cornfield. nitrogen is the nutrient that most commonly limits corn growth. The inset photo shows corn grown with adequate nitrogen (left) and in nitrogen-deficient soil (right).

37. 42.8 How Does Phosphorus Move Through the System?
Age structure diagrams show the ______________ of individuals among age groups
The broader the base of an age structure diagram, the _________ proportion of young people, and the __________ expected growth
More than 1/3 of the world population is in the broad pre-reproductive base
World population growth will not be slowed for many years

38. How Does Phosphorus Move Through the System? (cont’d.)
Most phosphorus is _____________ to oxygen as phosphate (PO43– ) in rocks and sediments – and moves in a sedimentary cycle

39. How Does Phosphorus Move Through the System? (cont’d.)
Steps in phosphorus cycle
_______________ and _____________ move phosphates from rocks into soil, lakes, and rivers
Leaching and runoff carry ____________ phosphates to the ocean
Phosphorus settles as ____________ along continental margins
Slow movements of Earth’s crust uplift deposits onto land, where weathering releases phosphates from rocks

40. How Does Phosphorus Move Through the System? (cont’d.)
Land plants ______________ dissolved phosphate from soil water
Land animals get phosphates by eating plants or one another; phosphorus returns to soil in wastes and remains
In seas, producers take up phosphate dissolved in seawater
Wastes and remains ______________ phosphates in seawater

41. How Does Phosphorus Move Through the System? (cont’d.)
Phosphorus is often a _________________ for plant growth
Phosphate-rich droppings from seabird or bat colonies are used as fertilizer
Phosphate-rich rock is also mined for this purpose
Water pollution from high-phosphate fertilizers, detergents, or sewage can cause ______________

42. ANIMATION: Phosphorus Cycle
Figure {Animated} The phosphorus cycle
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43. 42.9 Toxic Transfers Bioaccumulation
Nutrients are not the only things that move up food chains
____________ enter food chains and pass from one trophic level to the next
By the process of bioaccumulation

44. Toxic Transfers (cont’d.)
Figure Loon with its fish prey. Along with nutrients, the loon takes in any toxic pollutants that accumulated in the fish’s body.