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3.4 Cycles of Matter
Lesson Objectives
Describe how matter cycles among the living and nonliving parts of an ecosystem.
Describe how water cycles through the biosphere.
Explain why nutrients are important in living systems.
Describe how the availability of nutrients affects the productivity of ecosystems.
Lesson Summary
Recycling in the Biosphere Matter, unlike energy, is recycled within and between
ecosystems. Elements pass from one organism to another and from one part of the biosphere
to another through biogeochemical cycles, which are closed loops powered by the flow of
The Water Cycle Water moves between the ocean, the atmosphere, and land.
▶ Evaporation is the process in which water changes from a liquid to a gas.
▶ Transpiration is the process in which water evaporates from the leaves of plants.
Nutrient Cycles The chemical substances that an organism needs to survive are called
nutrients. Like water, nutrients pass through organisms and the environment.
▶ Carbon Cycle: Carbon is a key ingredient of all organic compounds. Processes involved in
the carbon cycle include photosynthesis and human activities such as burning.
▶ Nitrogen Cycle: Nitrogen is needed by all organisms to build proteins. Processes involved
in the nitrogen cycle include nitrogen fixation and denitrification.
• In nitrogen fixation, certain bacteria convert nitrogen gas into ammonia.
• In denitrification, other soil bacteria convert nitrogen compounds called nitrates back
into nitrogen gas.
▶ Phosphorus Cycle: Phosphorus is needed for molecules such as DNA and RNA. Most
of the phosphorus in the biosphere is stored in rocks and ocean sediments. Stored
phosphorus is gradually released into water and soil, where it is used by organisms.
Nutrient Limitation A nutrient that, in short supply, can limit the productivity of an
ecosystem is called a limiting nutrient.
Recycling in the Biosphere
For Questions 1–3, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
1. The four elements that make up over 95 percent of the body in most
organisms are oxygen, sulfur, nitrogen, and hydrogen.
2. Matter moves through an ecosystem in cycles.
3. Chemical and physical processes include the formation of clouds and
precipitation, “burning” food, and the flow of running water.
Lesson 3.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
The illustration draws
an analogy between the way energy drives
matter to cycle in an ecosystem and the way
water causes a waterwheel to turn. Give an
example of another analogy that could be
used to show the relationship between energy
and the cycles of matter.
les of Matter
Possible analogies include wind causing
a windmill to turn or a foot pushing a
bicycle pedal around and around.
5. Explain why Earth is considered a closed system.
Earth is a closed system because matter does not enter and matter does not escape.
The materials used by organisms cannot be lost; they are recycled.
6. How might building a new highway affect the cycles of matter?
When a new highway is being built, trees and other plants are cleared. The removal
of plants limits the food, energy, and habitats available to other organisms, like
animals. The removal of plants and animals stops nutrients from being recycled.
The Water Cycle
7. What role do plants play in the water cycle?
Plants absorb groundwater through their roots. That water re-enters the atmosphere
in the form of water vapor when it evaporates from the leaves of plants during
transpiration. This transpired water then continues the cycle.
Draw a diagram explaining the water cycle. Label the processes
involved as biological or physical/chemical.
Drawings should include the following: Physical/Chemical processes: Water
evaporates from bodies of water and then condenes into clouds in the atmosphere.
Water falls to the surface as precipitation. Surface runoff goes to rivers and oceans.
Water seeps into the ground and becomes groundwater. Biological Processes:
Groundwater is absorbed by plant roots. Plant leaves release water vapor into the
atmosphere through transpiration.
Lesson 3.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Nutrient Cycles
9. Complete the chart about the carbon cycle.
Processes That Cause Carbon to Move into
the Atmosphere
Processes That Cause Carbon to Move out
of the Atmosphere
the release of CO2
by an organism
after breaking down
carbohydrates into
usable energy
the use of sunlight
and CO2 to produce
Volcanic Activity
the release of CO2 and
other gases into the atmosphere through vents in
Earth’s crust
dissolves in rainwater
and oceans.
For Questions 10–12, write the letter of the correct answer on the line at the left.
The carbon in coal, oil, and natural gas came from
A. the combustion of fossil fuels.
B. the remains of dead organisms.
C. carbon-fixing bacteria in swamp soil.
D. carbon dioxide dissolved in ocean water.
How does most of the carbon in an organism’s body return to the
environment after the organism dies?
A. Decomposers break the body down into simpler compounds.
B. Heat from the sun causes the carbon in the body to evaporate.
C. Geological processes cause the body to turn into a fossil fuel.
D. Rainwater dissolves the carbon in the body and carries it to the ocean.
Human processes mainly contribute to the
A. release of carbon dioxide into the atmosphere.
B. decrease of the total amount of carbon found on Earth.
C. depletion of carbon dioxide reserves in the atmosphere.
D. increase in the amount of carbon contained in rock materials.
Lesson 3.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Write True if the statement is true. If the statement is false, change the underlined word or
words to make the statement true.
13. Nitrogen, in the form of ammonia, nitrate, and nitrite, is found in
the soil.
14. Nitrogen fixation is the process in which certain bacteria convert
nitrogen gas into nitrates.
15. Denitrification is the process by which some soil bacteria convert
nitrates into nitrogen gas.
16. All organisms require nitrogen to make amino acids, which in turn
are used to build carbohydrates.
17. Phosphate is released as rocks and sediments wear down.
18. Plants absorb phosphate from the soil or from water.
Carbon dioxide
19. Phosphorus is the most abundant gas in the atmosphere.
20. Organic phosphate is taken up by producers during photosynthesis
and released by cellular respiration.
21. Phosphorus forms part of the important life-sustaining molecules
such as DNA and RNA.
22. Plants absorb phosphorus from the atmosphere or water.
23. List and describe the biological steps in the nitrogen cycle.
Bacteria convert nitrogen gas into ammonia during nitrogen fixation. Other soil
bacteria convert ammonia into nitrates and nitrites. Primary producers use nitrates
and nitrites to make proteins and nucleic acids. Consumers eat producers and reuse
nitrogen to make compounds. Decomposers release nitrogen from waste and dead
organisms. Bacteria convert nitrates into nitrogen gas during denitrification.
24. What is atmospheric nitrogen fixation, and how does it affect organisms?
Atmospheric nitrogen fixation is the process in which lightning converts nitrogen gas
in the atmosphere into usable compounds. It makes nitrogen available to organisms.
25. How do humans add nitrogen to the biosphere?
Humans add nitrogen to the biosphere by using fertilizers that contain nitrogen.
26. Which parts of the phosphorus cycle are geological processes?
Geological activity turns marine sediments into rock and washes the phosphates from
the rock into the ocean.
Lesson 3.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Nutrient Limitation
Use the diagram of the interlocking nutrients to answer
Question 27.
The visual analogy compares
interlocking gears to the major nutrients—
potassium, phosphorus, and nitrogen. What other
“gears” would be affected if these gears stopped
working together?
Plants and other organisms can also be added to
this analogy. Without potassium, phosphorus and
nitrogen, plants would not be able to live and
thrive. Plants produce oxygen and carbohydrates.
Without these “gears,” animals and most living
things would not survive.
28. If a nutrient were in short supply in an ecosystem, how might it affect an organism?
It would limit an organism’s growth.
29. When is a substance a limiting nutrient?
A substance is a limiting nutrient when it is scarce or cycles very slowly and limits an
30. Compare and contrast the flow of energy through an environment with the flow of matter
through that same environment.
Matter moves through an environment differently than the way in which energy
moves. Energy is captured by producers and then passed in a linear progression from
one trophic level to the next. At each level, much of the energy escapes the ecosystem
as heat. Unlike this one-way flow of energy, matter is recycled within and between
ecosystems. Elements pass from one organism to another and among parts of the nonliving environment through closed loops called biogeochemical cycles.
Lesson 3.4 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Chapter Vocabulary Review
Match the term with its definition.
1. nutrient
2. chemosynthesis
3. consumer
4. ecosystem
5. photosynthesis
6. ecology
7. primary producer
8. biosphere
A. all the organisms in one area and their
physical environment
B. a process in which producers use chemical
energy to make carbohydrates
C. an organism that feeds on other organisms
D. a chemical substance that an organism needs
to survive
E. an organism that uses chemical or light
energy to produce its own food supply
F. the study of the biosphere
G. the portion of Earth and its atmosphere that
contains organisms
H. a process in which producers use light
energy to make carbohydrates
For Questions 9–12, complete the analogies.
9. omnivore : human :: carnivore :
10. detritivore : earthworm :: herbivore :
11. autotroph : heterotroph :: phytoplankton : zooplankton
12. biotic factor : elephant :: abiotic factor : precipitation
13. What is the difference between a food chain and a food web?
A food chain is a series of steps in which organisms transfer energy by eating and
being eaten. A food web is a network of several interacting food chains.
Complete each statement by writing the correct word or words.
14. There are several hundred squirrels living in an oak forest. The squirrels make up a(n)
population .
15. Fungi and some kinds of bacteria are
breaking down organic matter.
16. Ecologists measure
decomposers that obtain nutrients by chemically
in grams of organic matter per unit area.
17. In a process known as denitrification , some types of soil bacteria obtain energy by
converting nitrates into nitrogen gas.
Chapter 3 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Rhode Island’s Narragansett Bay is not the
only ecosystem that suffers from changes
in abiotic factors such as temperature. This
is happening within many biomes and
ecosystems around the world.
Rising Temperatures in a Lake
The northwest coniferous forest is a small biome along the coast of the northwestern United
States. It experiences seasonal variations in temperature and precipitation. Close to Seattle,
Washington, is Lake Washington, which is a freshwater ecosystem in peril from decades
of sewage dumping and rising water temperatures. The following is a brief summary of an
environmental report on Lake Washington.
ENVIRONMENTAL REPORT: Lake Washington Status
PREPARED BY: Environmental Sub-Committee
SUMMARY: While it has been more than 40 years since sewage has
been dumped into Lake Washington, problems still exist in this
freshwater ecosystem. The lake’s overall temperature has increased
by 0.5°C in the past 40 years. Its upper layer, which is 9 meters
deep, has experienced a temperature increase of 1.25°C. These
rising temperatures are negatively affecting the ecosystem’s food
chain. Zooplankton numbers are declining. These microscopic
organisms eat algae, which are at the base of the food chain.
Zooplankton are also prey for salmon. Higher temperatures are
generating more frequent algal blooms, which are starting to create
eutrophic conditions in the lake. Eutrophication is a condition in
which a body of water is very high in nutrients, but low in oxygen.
Salmon populations are also declining due to these conditions.
Spring turnover in the lake, a process by which warmer surface
water sinks and mixes with deep, cold water, is occurring a month
later than in the past. The result is that some fish that prefer colder
water are migrating into deeper waters, where they encounter
more predatory species than they would in shallow water. Studies
indicate that global warming is the major contributor to the rising
Continued on next page ▶
Chapter 3 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.
Science and Global
Awareness, Science and Civic Literacy
1. What abiotic factor is changing the ecosystem of Lake Washington, and how has this
factor changed over time?
Temperature is the abiotic factor that is changing the ecosystem. Both the top layer
temperature and the overall temperature of the lake are increasing.
2. Explain how this change has affected the mixing of warm and cold water in the lake. How
does this in turn affect fish?
The warmer temperatures have delayed the yearly springtime mixing of warm and cold
water in the lake. Consequently, some fish that prefer colder water migrate to deeper
water layers that are cooler but that hold larger populations of predatory fish species.
3. This report suggests that global warming is a primary contributor to the increased
temperature in the lake. What does this suggest about other lake ecosystems in the
northwest coniferous forest?
Other lakes in the northwest coniferous forest may also have increased water
temperatures. Their fish, algae, and zooplankton populations may also be in danger.
Seasonal turnover may also be later, as it is in Lake Washington.
4. Briefly describe a food chain in Lake Washington.
Algae are at the bottom of the food chain and are eaten by zooplankton. Salmon eat
the zooplankton.
5. If the zooplankton population is decreasing in Lake Washington, what do you think is
happening to the salmon population? Explain your answer.
The salmon are not able to find as much food, and their numbers are decreasing.
Lake Presentation
The skills used in this activity include critical thinking and systems thinking; problem
identification, formulation, and solution; communication; information literacy; and
leadership and responsibility.
Working with a small group, research information about Lake Washington’s past issues
with sewage disposal and current trends in increasing water temperature. Or, conduct
research about a body of water in your community or state. You may find it helpful to start
your research at the Web sites of federal and state environmental agencies. Visiting your
local public library and inquiring at government offices can offer valuable information, too.
Find evidence about the relationship between global warming and these rising temperatures.
Prepare a presentation describing the information that you find. In your presentation,
provide at least one example and show the effects of changing conditions on this ecosystem.
Present your findings to the class in an oral report, using figures, tables, and illustrations.
Evaluate students’ presentations by their inclusion of descriptions and past
and current data about the body of water, including charts, graphs, and/or diagrams.
Evaluation should also depend on the reliability of the sources students use.
Chapter 3 • Workbook A • Copyright © by Pearson Education, Inc., or its affiliates. All Rights Reserved.