Ecology
CHAPTER
2
Understanding Ecosystems
KEY QUESTION: How are organisms affected by living and non-living things
in their environment?
KEY CONCEPTS
Energy passes through ecosystems, but matter cycles within ecosystems.
Photosynthesis and respiration are processes that work together.
Aquatic and terrestrial ecosystems are strongly influenced by their abiotic
environment.
Human activities disturb the natural cycles of nature
2.1 Life on Earth
A habitat is a place where an organism lives.
All of Earth’s habitats can be divided into two main types:
1. Terrestrial (land)
2. Aquatic (water).
2.1 The Spheres of Earth
The Atmosphere – Atmos meaning vapour
Earth’s atmosphere is the layer of gases surrounding Earth made of water
vapour, oxygen (21%), nitrogen (78%) and carbon dioxide.
The atmosphere supports life. It acts like a blanket, moderating surface
temperatures. It also blocks some incoming solar radiation.
The Lithosphere – Litho meaning stone
The lithosphere is the rocky outer shell of Earth that makes up the
mountains, ocean floors, and the rest of the solid landscape.
2.1 The Spheres of Earth
The Hydrosphere – Hydro meaning water
The hydrosphere consists of all the water on, above, and below Earth’s
surface it includes oceans, lakes, ice, groundwater, and clouds.
The Biosphere – Bio meaning life
The biosphere is all the locations on Earth where life can exist within the
lithosphere, atmosphere, and hydrosphere.
2.2 Introducing Ecosystems
An ecosystem is all of the living organisms that share a
region and interact with each other and their non-living environment.
Ecosystems include living (biotic), and non-living (abiotic) factors.
• Biotic factors include organisms, their remains, and their products or
wastes.
• Abiotic factors include temperature, wind, water, minerals, and air.
2.2 Populations and Communities
An ecosystem may be large or small and can
contain many or just a few organisms. Scientists
group these individual organisms into
populations and the populations into
communities.
• A population is all individuals of the same
species living in an ecosystem.
• A community is all organisms living in the
same ecosystem.
Single organism

Population
(group of 1 species)

Community
(group of different species)

Ecosystem
(community + abiotic factors)
2.3 Sustainability of Ecosystems
• Most natural ecosystems are sustainable.
• Human activities can render a previously sustainable ecosystem unsustainable.
Setting limits on hunting, fishing and development help keep ecosystems
sustainable.
• Human actions can create artificial ecosystems, such as an urban park or farm.
Artificial ecosystems are not usually sustainable and must be maintained by
humans.
• To keep our natural ecosystems sustainable simple advice to follow is: take only
pictures and leave only footprints.
http://www.brainpop.com/science/ecologyandbehavior/ecosystems/preview.weml
2.5 Energy Flow in Ecosystems
• All organisms require energy to stay alive and function.
• Radiant energy from the Sun is the source of almost all
this energy.
• The Sun emits invisible radiant energy, including ultraviolet, and visible
radiant energy, or light energy.
• About 70 % of radiant energy is absorbed by the hydrosphere and lithosphere
and converted into thermal energy, warming Earth.
2.5 Energy Flow in Ecosystems
• In order for organisms to use the energy from the Sun, it must first be
converted into chemical energy. Some organisms convert the suns energy
directly into chemical energy (producers), others must eat food to obtain
their energy (consumers).
• Chemical energy can be stored and used by organisms when they need it.
2.5 Photosynthesis
• Chemical energy is used by all organisms to perform functions such as
growth and reproduction.
• Many organisms can convert light energy into chemical energy using the
process of photosynthesis.
• Organisms like plants that photosynthesize are called producers.
• On land, the main producers are green plants.
• In water, the main producers are microscopic organisms.
2.5 Producers Store Chemical Energy
Through Photosynthesis
• Most producers contain chlorophyll, which they use to
capture light energy. Chlorophyll makes plants appear green.
• Producers use light energy to convert carbon dioxide and
water into sugar. Plants store the sugars in their roots,
stems, leaves, and seeds.
• During photosynthesis plants also release oxygen gas into
the atmosphere.
• The word equation for photosynthesis is
2.5 Cellular Respiration - Consumers
• Many organisms cannot photosynthesize. Instead, they obtain energy by
eating other organisms. These organisms are called consumers.
• Humans are consumers. We depend on photosynthesizing organisms for
food and oxygen.
• Only producers undergo photosynthesis, but both producers and
consumers undergo cellular respiration.
Producers—Produce their own food. i.e. Plants
Consumers—Must eat (consume) their food. i.e. Bears
2.5 Cellular Respiration - Consumers
• Cellular respiration is a complementary process to photosynthesis.
This means the reactions are opposite to each other. Photosynthesis
stores energy in sugars and cellular respiration releases the energy.
Sugar + oxygen  carbon dioxide +water + energy
• Both process need to happen in order to sustain life.
2.6 Ecological Niches
• Every species interacts with its environment and other species in a unique way this is
called an ecological niche.
• An ecological niche includes what a species feeds on, what eats it, and how it behaves.
No two species have the same niche.
• Consumers can be subdivided depending on what types of organisms they eat.
• Herbivore – consume and eat only producers (Animals that only eat plants)
• Carnivore – consume and eat only consumers (Animals that eat other animals)
• Omnivore – consumer that eats both producers and consumers (Animals that eat both
plants & animals)
• Scavengers - Eat dead stuff (i.e. seagulls)
• Decomposers – consumers that feed on dead decaying organisms (ie. mold - Eat dead
stuff)
2.6 Food Chains
• Food chains show the feeding relationships between species in an ecosystem.
• In a food chain help show how the chemical energy is passed through an
ecosystem.
• Organisms continually use and release energy to their environment, energy is
continuously lost from all levels of the food chain.
• The trophic level describes the position of an organism along a food chain.
When one organism eats another organism it passes its stored chemical energy
up to the next trophic level. Typically only 10% of the energy is passed
between trophic levels.
2.6 Food Webs
• Food chains are used as a tool to show simple feeding relationships, but
they do not show the complex feeding relationships in an ecosystem.
• A food web is a more accurate way to illustrate feeding relationships by
linking the food chains in an
ecosystem and including decomposers.
• Food webs help scientists understand how
changes affect ecosystems by showing which
organisms will be affected by any change.
• How do humans disrupt a food change?
TRY THIS!
On page 44, complete the activity
“You and Your Food Chain”
2.7 Cycling of Matter in an Ecosystem
• Matter is always moving through an ecosystem being
recycled and used over again.
• All water and nutrients in an ecosystem must be
obtained from chemicals already in the
environment.
• Chemicals on Earth are continuously consumed,
rearranged, stored, and used in a series of cycles
called biogeochemical cycles.
• There are four main cycles: carbon; water;
nitrogen and phosphorous.
• The water cycle is the cycling of water
through the environment as a liquid, gas
and solid.
2.7 Cycling of Matter in an Ecosystem –
The Carbon Cycle
• Carbon is found in both the abiotic and biotic parts of an ecosystem in the
carbon cycle
• One way carbon is cycled is through photosynthesis and respiration.
• Most of Earth’s carbon is stored in deposits such as coal, ocean sediments,
limestone, oil and natural gas. These deposits were left when
decomposed organisms are compressed.
• By burning fossil fuels, humans release stored carbon into the
atmosphere. This has a dramatic effect on the carbon cycle.
2.7 Cycling of Matter in an Ecosystem –
The Carbon Cycle
• Deforestation also increases the concentration
of carbon dioxide in the atmosphere.
• The increase in carbon
dioxide and carbon monoxide
is causing global climatic
change.
2.8 Biotic and Abiotic Influences on
Ecosystems
• A limiting factor determines the types and numbers of organisms an
ecosystem can support. Limiting factors can be biotic (for example, lack
of food) or abiotic (for example, access to water).
• Every species is able to survive within a range of abiotic factors such as
temperature, light, and soil. This range is called the species’ tolerance
range.
2.8 Biotic and Abiotic Influences on
Ecosystems
• Abiotic factors determine where a species can live; biotic factors often
determine how easy a species can survive in that location.
• Many key biotic factors involve interactions between individuals;
competition, predation, mutualism, commensalism and parasitism.
2.8 Carrying Capacity
• As a population’s size increases it needs more food, water and space.
Eventually the population reaches a maximum size for the amount of
available resources.
• This is called the carrying capacity of an ecosystem.
• The carrying capacity can be altered through natural or human activity
when resources are removed or added to the ecosystem. Factors that
can change carrying capacity: Food; Weather; Habitat Loss; Predation,
Disease and Competition.
2.9 Terrestrial Biomes
• Each environment has a unique mix of organisms forming unique
communities and ecosystems. These areas that have similar climate,
temperature, precipitation and organisms are called biomes.
• There are five major terrestrial biomes have distinct biotic and abiotic
factors:
• Tundra - a cold, barren biome in the northernmost part of Canada.
Low temperatures and a short growing season limit plant growth
• Boreal Forest - the largest biome in Canada. Warm temperatures
and rainfall in summer encourage tree growth
2.9 Terrestrial Biomes
• Mountain Forest – temperatures vary in Canada’s mountain forest
biome
• Grassland – animals found in southern Canada’s natural grassland
biome include coyotes, foxes, prairie dogs, and burrowing owls
• Temperate Deciduous Forest – home to a great variety of deciduous
trees such as maples, oaks, and ashes.
2.9 Location of Canada’s Major Biomes
2.9 Aquatic Biomes
• Aquatic Biomes are divided into Freshwater and Marine Biomes
Freshwater Ecosystems
• Only 3 % of the water on the planet is considered freshwater.
• Freshwater ecosystems include rivers, streams, lakes, and ponds.
• Wetlands are freshwater ecosystems that are large areas of saturated soil
they include bogs, swamps and marshes.
• Wetlands play an important role in the filtering of freshwater and provide
home to many species of birds, fish, amphibians and reptiles.
2.9 Aquatic Biomes
• Aquatic Biomes are divided into Freshwater and Marine Biomes
Watersheds
• A watershed is an area of land through which all water drains into a
single river or lake.
• If a pollutant enters a watershed,
it could affect areas downstream.
2.9 Marine Ecosystems
• Oceans cover more than 70 % of Earth’s surface.
• Most of the water that evaporates and then falls as precipitation
comes from oceans.
• Half of the oxygen produced through photosynthesis comes from
organisms living in Earth’s oceans.
• There are many marine ecosystems.
•
Shallow near shore ecosystems are nutrient rich and support
abundant life.
• Coral reefs
• Estuaries
• Mangroves
Whales, Darts, and DNA
Crime shows on television often show criminal cases being solved
using evidence such as DNA fingerprinting. This same technology is
now being used to save endangered species of whales.
For years, scientist Scott Baker, from the University of Auckland, New
Zealand, studied endangered humpback whales in the Pacific Ocean.
Baker was puzzled that humpback whales were not increasing in
number after a hunting ban was imposed in 1986. Baker had a
hypothesis. He knew that Japan allowed the sale of whale meat from
species that were note protected. He suspected that some whale
meat being sold was also from whales that were protected.
CHAPTER
2
LOOKING BACK
KEY CONCEPTS SUMMARY
Energy passes through ecosystems, but matter cycles within
ecosystems.
• Energy is passed through ecosystems when organisms eat other
organisms.
• Energy is lost to the environment as thermal energy.
• Matter moves through ecosystems in cycles known as
biogeochemical cycles.
CHAPTER
2
LOOKING BACK
KEY CONCEPTS SUMMARY
Photosynthesis and respiration are processes that work
together.
• In photosynthesis, plants make food in which energy is stored.
• Cellular respiration releases stored energy for use.
CHAPTER
2
LOOKING BACK
KEY CONCEPTS SUMMARY
Aquatic and terrestrial ecosystems are strongly influenced by
their abiotic environment.
• Temperature and water content are important factors in
terrestrial ecosystems.
• Temperature and salt concentration are important factors in
aquatic ecosystems.
CHAPTER
2
LOOKING BACK
KEY CONCEPTS SUMMARY
Human activities disturb the natural cycles of nature.
• Human activities change abiotic factors that influence
organisms.
• Human activities may remove species from ecosystems or
introduce new species to ecosystems.
CHAPTER
2
Quiz
Multiple Choice
1. Which word equation shows the process of photosynthesis?
a. sugar + oxygen  carbon dioxide + water + energy
light energy
b. carbon dioxide + oxygen
sugar + water
light energy
a. carbon dioxide + water
sugar + oxygen
b. sugar + water  carbon dioxide + oxygen + energy
2. Predation is when …
a. One individual benefits and the other is neither harmed
or benefits.
b. Both benefit each other.
c. Both species seek the same resource.
CHAPTER
2
Quiz
Multiple Choice
3.Herbivores are?
a. Consumers that eat only plants or producers.
b. Consumers that eat other consumers.
c. Consumers that eat producers and consumers.
d. Consumers that eat dead and decaying organisms.
4.As energy is transferred from one trophic level to another how
much is taken?
a. 3 %
b. 10 %
c. 90 %
d. 97 %
CHAPTER
2
Quiz
Fill in the Blanks
Use the words in the wordbank below to complete the following
sentences.
5.
The ________________ includes all the gas on the planet, the
_______________ includes all the rock and soil, the
__________________ contains all the water and the
__________________ includes all the living material on Earth.
6.
by a
A (n) ___________factor is a living thing or something produced
living thing. A(n) _____________factor is a non-living thing.
hydrosphere, abiotic, atmosphere, biotic, producer, food chain,
sustainability, food web, consumer, lithosphere, trophic, biosphere
CHAPTER
2
Quiz
Fill in the Blanks
Use the words in the wordbank below to complete the sentences.
7.
of
_________________is the ability to maintain natural ecological
conditions or processes without interruption, weakening, or loss
value.
8.
light
A ___________________ makes its own energy-rich food using
energy. A _____________ eats other organisms for food.>
9.
A ____________ only shows one species at each ___________
level. A __________________ shows a variety of species at each
level, along with the complex feeding relationships between
them in an ecosystem
hydrosphere, abiotic, atmosphere, biotic, producer, food chain,
sustainability, food web, consumer, lithosphere, trophic, biosphere
CHAPTER
2
Quiz
Match the label in the wordbank to the letter.
b.
a.
e.
c.
d.
Grassland; Mountain Forest; Boreal Forest; Tundra; Temperate
Deciduous Forest
CHAPTER
2
Quiz Answers
Multiple Choice
1. Which word equation shows the process of photosynthesis?
a. sugar + oxygen  carbon dioxide + water + energy
light energy
b. carbon dioxide + oxygen
sugar + water
light energy
c. carbon dioxide + water
sugar + oxygen
d. sugar + water  carbon dioxide + oxygen + energy
2. Predation is when …
a. One individual benefits and the other is neither harmed
or benefits.
b. Both benefit each other.
c. Both species seek the same resource.
CHAPTER
2
Quiz Answers
Multiple Choice
3.Herbivores are?
a. Consumers that eat only plants or producers.
b. Consumers that eat other consumers.
c. Consumers that eat producers and consumers.
d. Consumers that eat dead and decaying organisms.
4.As energy is transferred from one trophic level to another how
much is taken?
a. 3 %
b. 10 %
c. 90 %
d. 97 %
CHAPTER
2
Quiz Answers
Fill in the Blanks
Use the words in the wordbank below to complete the following
sentences.
5.
The atmosphere includes all the gas on the planet, the
lithosphere
includes all the rock and soil, the hydrosphere
contains all the water
and the biosphere includes all the living
material on Earth.
6.
living
A biotic factor is a living thing or something produced by a
thing. An abiotic factor is a non-living thing.
hydrosphere, abiotic, atmosphere, biotic, producer, food chain,
sustainability, food web, consumer, lithosphere, trophic, biosphere
CHAPTER
2
Quiz Answers
Fill in the Blanks
Use the words in the wordbank below to complete the sentences.
7.
Sustainability is the ability to maintain natural ecological
conditions or
processes without interruption, weakening, or loss of
value.
8.
A producer makes its own energy-rich food using light energy. A
consumer eats other organisms for food.
9.
A food chain only shows one species at each trophic level. A
food
web shows a variety of species at each level, along with the
complex
feeding relationships between them in an ecosystem
hydrosphere, abiotic, atmosphere, biotic, producer, food chain,
sustainability, food web, consumer, lithosphere, trophic, biosphere
CHAPTER
2
Quiz Answers
Match the label in the wordbank to the letter.
b.Tundra
a.
Mountain Forest
e. Boreal Forest
c. Grassland
d. Temperate Deciduous
Forest