How Disturbed is Too Disturbed?
(Page 5)
If you consider an ecosystem to be similar to a pile of interlocking
blocks, how does the removal of blocks from different parts of the pile
affect the structure of the “ecosystem” as a whole?
How might an actual ecosystem behave differently than the pile of
blocks?
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.1 Sustainability
(Page 7)
An ecosystem is described as being all
the interacting parts of a biological
community and its environment.
A sustainable ecosystem is one that is
capable of withstanding pressure and
giving support to a variety of organisms.
As noted by the Easter Island example
on page 7 of the text, humans have the
potential to inflict catastrophic changes
on an ecosystem. These changes can
greatly affect an ecosystem’s
sustainability.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Ecosystems and Survival
(Page 8)
All organisms require sustainable ecosystems for their survival. Many
organisms depend on more than one ecosystem to survive.
The range of the Rubythroated hummingbird
covers a good portion of
North America and a
variety of different
ecosystems.
The Sargasso eel
encounters many
ecosystems as it moves
from the Sargasso Sea
to the Great Lakes.
As demonstrated by the examples above, some organisms encounter
a variety of different ecosystems as they live their lives.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Parts of an Ecosystem
(Page 9)
Every ecosystem has biotic and abiotic parts.
• Biotic refers to the living parts of an ecosystem (including plants,
animals, and micro-organisms).
• Abiotic refers to the non-living parts of an ecosystem (including
water, oxygen, light, nutrients, and soil).
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Biotic Interactions in an Ecosystem
(Page 10)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Biotic Interactions in an Ecosystem
(Page 10)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Abiotic Characteristics of an Ecosystem
(Page 12)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Abiotic Characteristics of an Ecosystem
(Page 12)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cycling of Matter and Earth’s Spheres
(Page 13)
Ecological processes move matter from the biotic and abiotic parts of
an ecosystem and back again in continuous cycles.
•The lithosphere is the hard
part of Earth’s surface.
•The hydrosphere is all of the
water found on Earth (lakes,
oceans, and ground water).
•The atmosphere is the layers
of gas above Earth’s surface.
•The biosphere is the regions
of Earth where living
organisms exist.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: Water
(Page 14)
Nutrients are chemicals that are needed by living things and are
continually cycled through ecosystems.
The water cycle
moves water
through the
hydrosphere,
atmosphere, and
lithosphere. This
occurs by way of
evaporation,
condensation, and
precipitation.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: Carbon
(Page 15)
The carbon cycle moves
carbon through all of Earth’s
spheres. Carbon exists as a
gas—carbon dioxide (CO2)—
in the atmosphere. This gas is
used by plants to make
sugars. Sugars are broken
down by organisms to release
energy and CO2. Carbon is
stored in fossil fuels buried
within Earth and in carbonate
(CO3) rock found in the
lithosphere.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: Nitrogen
(Page 16)
The nitrogen cycle moves nitrogen through Earth’s spheres. Nitrogen
gas (N2) from the air is converted into ammonium (NH4) and into
nitrates (NO3) by bacteria and cyanobacteria.
In terrestrial (land
based) ecosystems,
ammonium (NH4) is
produced by soil
bacteria. In aquatic
(water based)
ecosystems, NH4 is
produced by
cyanobacteria.
Nitrates (NO3) are
produced from
ammonium.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: Phosphorus
(Page 17)
The phosphorus cycle moves phosphorus from the lithosphere,
where it is stored in rocks as phosphate (PO43-), to the hydrosphere by
the processes of leaching and run-off. Plants then use the
phosphorus.
The phosphates in
plants and
animals are
released back into
the soil by
bacterial
decomposition.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycle Review
Click the “Start” buttons to review the various nutrient cycles.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Human Activities and Nutrient Cycles
(Page 18)
Aquatic ecosystems suffer when run-off contains high amounts of
agricultural fertilizers (which are high in nitrates and phosphates). The
added nutrients can lead to the eutrophication of bodies of water.
Eutrophication is a process in
which nutrient levels in aquatic
ecosystems increase, leading to
an increase in the populations of
primary producers, such as algae.
Eutrophication
eventually leads
to a reduction
in the oxygen
content of the
water.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Science and Social Policy
(Page 19)
Both Canada and the United States have signed the Great Lakes Water
Quality Agreement to help to “restore and maintain the chemical,
physical, and biological integrity of the waters of the Great Lakes
Basin Ecosystem.”
Environmental farm plans and by-laws
have been developed to decrease the
amount and number of chemicals that
enter Canadian waterways from
Canadian farms.
The satellite image above shows an algal bloom in the
western basin of Lake Erie which was caused by
elevated nutrient levels.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Section 1.1 Review
(Page 20)
Concepts to be reviewed:
• Why do we want ecosystems to be sustainable?
• How does matter, including nutrients, move through Earth’s
spheres?
• How can human activities increase the nutrients entering
terrestrial and aquatic ecosystems? What effect do the nutrients
have?
• What decisions and/or actions can be taken to protect the health
of ecosystems?
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.2 The Biosphere and Energy
(Page 21)
Nuclear reactions in the Sun are the energy source for almost all life
on Earth.
The energy received from the Sun warms Earth’s atmosphere and
makes Earth habitable. The conversion of solar energy to chemical
energy, in the form of food, is carried out by plants, algae, and some
bacteria, through the process of photosynthesis.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
What Happens During Photosynthesis?
(Page 22)
In the process of photosynthesis, the chlorophyll in plant leaves uses
solar energy to assemble glucose molecules from water and carbon
dioxide. Oxygen is also produced during the process.
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Reviewing Photosynthesis
Click the “Start” button to review the process of photosynthesis.
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Sources of Oxygen
(Page 23)
In addition to producing a form of chemical energy that can be used
to sustain plants and animals, photosynthesis continuously adds
oxygen (O2) to the atmosphere and removes carbon dioxide (CO2).
On a global basis, phytoplankton in the oceans is the biggest
contributor to the production of oxygen.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Trophic Levels
(Page 24)
A trophic level is a category of organisms that is defined by how the
organisms gain their energy. Energy moves from one level to the next.
Primary producers are organisms that make their own food.
Consumers must eat other organisms to get the food (matter and
energy) they need to survive.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Trophic Efficiency
(Page 25)
An energy or biomass pyramid shows how the energy stored in
biomass at one trophic level moves from the bottom to the top of a
food chain.
Biomass is the total
mass of living
organisms in a
defined group or
area.
Trophic efficiency is a measure of the amount of energy or biomass
transferred from one trophic level to the next higher trophic level.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Trophic Level Virtual Lab
Click the “Start” button to review the interactions between different trophic levels
and the transfer of energy through an ecosystem.
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_02/BL_02.html
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Water Pollution and Bioaccumulation
(Page 26)
Bioaccumulation is a process in which materials, especially toxins, are
ingested by an organism at a rate greater than they are eliminated.
The level of toxins such as DDT (dichloro-diphenyl-trichloroethane)
and PCBs (polychlorinated biphenyls) is highest in the highest trophic
levels.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Reviewing Bioaccumulation
Click the “Start” button to review bioaccumulation.
http://www.mhhe.com/cgibin/netquiz_get.pl?qfooter=/usr/web/home/mhhe/biosci/genbio/animation_quiz
zes/animate_9fq.htm&afooter=/usr/web/home/mhhe/biosci/genbio/animation_
quizzes/animate_9fa.htm&test=/usr/web/home/mhhe/biosci/genbio/animation_
quizzes/animate_9q.txt&answers=/usr/web/home/mhhe/biosci/genbio/animatio
n_quizzes/animate_9a.txt
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Section 1.2 Review
(Page 27)
Concepts to be reviewed:
• Where does the biosphere get the energy it relies on?
• How does photosynthesis convert solar energy into chemical
energy?
• How does energy move from one trophic level to the next?
• How can bioaccumulation and biomagnification negatively affect
organisms?
Copyright © 2010 McGraw-Hill Ryerson Ltd.
1.3 Extracting Energy from Biomass
(Page 28)
Although not all organisms undergo photosynthesis, all organisms—
from single-celled bacteria to complex, many-celled life forms—get
energy from glucose.
Cellular respiration is a process
that releases energy from
organic molecules, especially
carbohydrates, in the presence
of oxygen.
Fermentation also releases
energy but in the absence of
oxygen.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Extracting Energy from Food
(Page 29)
In cellular respiration, organisms take in oxygen, which reacts with
the glucose in cells to produce carbon dioxide, water, and energy.
During the day, plants produce glucose through photosynthesis. At
night and during the day, plants extract energy from the glucose
using the process of cellular respiration.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Reviewing Photosynthesis and Cellular Respiration
Click the “Start” button to review the connection between photosynthesis and
cellular respiration in plants.
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Carbon Dioxide and Other Greenhouse Gases
(Page 29)
Greenhouse gases are atmospheric gases that prevent heat from
leaving the atmosphere, thus increasing the temperature of the
atmosphere. The greenhouse effect is the warming of Earth as a
result of increased greenhouse gases that trap heat energy that
would otherwise leave Earth.
Carbon dioxide
(CO2) is the most
common of the
greenhouse gases.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Biomass and Fossil Fuels
(Page 30)
Because fossil fuels come from biomass that was produced by
photosynthesis millions of years ago, burning them has an effect very
similar to cellular respiration. They both produce large quantities of
carbon dioxide (a greenhouse gas) that may contribute to global
warming.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Reducing Carbon Dioxide in the Atmosphere
(Page 31)
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Fermentation, Methane, and Landfills
(Page 32)
Methane (CH4) is produced by bacteria when they break down
organic waste using fermentation. Landfills, dumps, and swamps can
produce large amounts of methane.
Methane produced by bacteria in landfills can be captured,
processed, and then burned to generate electricity for use in homes
and businesses.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Acid Precipitation
(Page 33)
In addition to producing greenhouse gases when burned, fossil fuels
also produce undesirable compounds such as nitrogen oxide (NOX)
and sulphur dioxide (SO2) that combine with water in the air to form
nitric and sulphuric acid. These compounds contribute to acid
precipitation, which is rain, snow, or fog that has a pH less than 5.6.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Measuring pH
(Page 34)
A substance’s pH is an indication of how acidic or basic it is. The pH
scale ranges from 0 to 7. Substances with a pH:
• lower than 7.0 are considered acidic
• equal to 7.0 are considered neutral
• greater than 7.0 are considered basic
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Effects of Acid Precipitation
(Page 34)
Continued exposure to acid rain can remove soil
nutrients such as calcium and increase the level
of soil nutrients such as aluminum. These
changes can lead to the death of trees and, thus,
the loss of forests.
Acid precipitation is even more devastating to aquatic ecosystems.
Many aquatic organisms have a very low tolerance to changes in the
pH of the water they live in.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Reducing Acid Precipitation
(Page 35)
Acid precipitation remains a problem, but the situation seems to be
improving. Agreements between Canada and the United States plus
new laws have reduced the level of cross-border pollutants. Through
the use of scrubbers to remove undesirable gases from industrial
emissions and with higher standards for motor-vehicle emissions, acid
precipitation has been reduced since the 1980s.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Section 1.3 Review
(Page 36)
Concepts to be reviewed:
• How do organisms use cellular respiration and fermentation to
extract energy from glucose?
• How has the burning of fossil fuels affected the concentrations of
greenhouse gases in the atmosphere?
• What is acid precipitation? What causes it? How does it affect
living things?
• What measures have been taken to reduce acid precipitation?
Copyright © 2010 McGraw-Hill Ryerson Ltd.