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ECOSYSTEMS
Part 2
Joseph Priestly
Joseph Priestly was an English clergyman
and scientist. He noticed that if he put a
burning candle in a jar, the candle went
out after a few minutes and when he put
a mouse in the jar, the mouse died. When
Priestly added a green plant to the jar the
candle did not go out as quickly and the
mouse survived.
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Producers
If we wanted to pick the single most
influential abiotic element that influences
life on Earth it should probably be the Sun.
Producers
The Sun provides us with
energy in the form of light and
heat, both of which are
important for most if not all
forms of life either directly or
indirectly. Plants need light to
make food and in the Spring, it
is the rising of temperatures
that signals and triggers
growth.
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Producers
The one thing that makes plants so
amazingly important in all our lives is the
fact that they can produce their own
food from light, water and the gas carbon
dioxide (CO2). This is why we call them
producers.
Photosynthesis
Water + carbon dioxide + light energy
Sugar (glucose) + oxygen
6CO2 + 6H2O C6H12O6 + 6O2
You can see how mathematically, it
balances the scale.
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Cellular Respiration
The process by which cells release the
energy stored in sugars (obtained from
food) is called cellular respiration.
Sugar + oxygen
carbon dioxide + water + energy
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Bean Seeds and
Germination
Complete the Bean Seeds and
Cellular Respiration worksheet.
Remember that a hypothesis is a
statement of what you expect to occur
Remember that a test is how you
determine the accuracy of the
hypothesis
Remember that a result is what actually
occurs
Producers
In the end, almost all types of organisms
on our planet (there are exceptions)
either depend directly on the Sun, which
means they are plants, or they eat plants
or they eat things that have eaten plants
or they eat things that have eaten plants,
or… well, you get the picture.
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Food Chain
This is a logical, singular way to examine
the sources of food:
Wheat mouse snake hawkProducer primary consumer secondary consumer tertiary consumer
Ecological Pyramids
All pyramids need a large base – for ecological pyramids this is where we place the producers.
Ex: grass, wheat, leaves, reeds…
The next level is smaller – this is where we place primary consumers (also called an herbivore)
Ex: mouse, cow, deer…
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Ecological Pyramids
The third level on a pyramid is again smaller – this is where the secondary consumers are placed (would include carnivores or omnivores)
Ex: raccoon, human, lion, shark…
The next level is smallest – this is where we place tertiary consumers (includes carnivores and omnivores that consume creatures that have already consumed another non-plant life).
Ex: human, snake, owl, shark…
Ecological Pyramids An ecological pyramid is a graphic
representation of the relationships among the different components of a food chain. It can illustrate
The number of organisms at each level (pyramid of numbers)
The amount of biomass (pyramid of biomass) at each level
The energy lost at each level (pyramid of energy)
Only a small percentage (approximately 10%) of the food energy is available to the next level of a food chain.
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Ecological Pyramids
1 hawk
(tertiary consumer)
3 snakes
(secondary consumer)
20 mice
(primary consumer)
200 grains of wheat
(producer)
What to Eat?
Four hectares of corn will support 1000 people for one day. If those same hectares of corn were fed to cattle and then the cattle were eaten by people, there would only be enough beef to feed 50 people for one day.
What are the implications of this knowledge to North America? What are the implications to countries where food is in short supply?
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Transfer of Energy in an
Ecosystem Using the diagram:
1. What would happen to the food chain if only 100 grains of
wheat were available instead of 200?
2. What might cause a reduction in the amount of wheat
available?
3. What other natural or human-caused events could take
place, and what effect would they have on the ecological
pyramid?1 hawk
(tertiary consumer)
3 snakes
(secondary consumer)
20 mice
(primary consumer)
200 grains of wheat
(producer)
Transfer of Energy in an
Ecosystem Using the diagram:
1. What other food sources exist for mice, snakes, and hawks?
2. Why might it be useful to have more than one food source?
3. What statement can you make regarding the transfer of
energy within an ecosystem and the implications of the loss
of producers and consumers to this transfer?
1 hawk
(tertiary consumer)
3 snakes
(secondary consumer)
20 mice
(primary consumer)
200 grains of wheat
(producer)
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Deadly Links Game
Bioaccumulation or
Biological Amplification
The process that results in increasing
concentrations of a harmful chemical at
each higher level of a food chain.
Discuss the pros and cons of using toxic
chemicals, identifying perspectives from
the various groups involved.
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Mercury Bioaccumulation Mercury is a poisonous substance that can
affect the functioning of body systems. Mercury levels in water have fluctuated in the past years. In the 1970s, there were high levels of mercury found in some areas due to discharges from pulp and paper mills. Laws have since been implemented to monitor and regulate the amount of mercury that can enter water systems. In addition, quotas have been imposed by the government on the number and type of fish that can be caught. These quotas are placed on large predatory fish only, and do not apply to small fish. Why do you think this is?
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Scavengers and Decomposers
Using the laptops, help create a class list
of scavengers and decomposers.
Investigate the purpose of scavengers
and decomposers in an ecosystem.
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Interactions within an
Ecosystem
We have discussed how producers are
consumed by other organisms – this
creates what we call a parasitic
relationship.
This is when one organism benefits (the
“parasite”), while the other organism
suffers (the “host”).
Interactions within an
Ecosystem
A second type of interaction is called
mutualism.
This is a type of interaction in which both
organisms are benefiting.
For example: A honeybee with a flower.
The Honeybee gets food
from the flower (nectar)
while the flower gets the bee
to distribute it’s pollen.
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Interactions within an
Ecosystem
The third interaction type is called
commensalism.
This is when one organism gains while the
other organism is neither helped
nor harmed.
An example of this would be army
ants and birds. The army ants go
around attacking other insects. The
insects capable of flight will fly away. As
they leave, the birds swoop in and eat
them.
Symbiotic Relationship
Some mutually beneficial interactions go
so deep and are so prolonged that both
species depend on one another in such a
was that they are called symbiotic –
meaning “living together”
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The clownfish feeds on small invertebrates that otherwise have potential to harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone’s stinging cells, to which is it immune.
Populations and Communities
As we consider interactions in the
environment, we are not only looking at
the way that individual living things
interact with one another but we will also
consider entire populations and
communities.
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Populations
Populations are collections of individuals
that belong to the same species that live
in the same area. An example would be
all the geese of the same species in a
pond.
Species
A species is the collection of all individuals
that are so closely related genetically that
they can produce fertile offspring.
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Some organisms are
able to reproduce,
but their offspring are
sterile, which means
that the offspring
cannot reproduce.
Community
A community is made up of populations
of different species that live in the same
ecosystem. The interactions between
these populations and the local abiotic
elements make up the ecosystem.
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Community
Consider a pond, for example. In that
pond are a variety of insects and
amphibians. Many of the different species
of amphibians may compete for the
same insects as a food source and may
be subject to predation by snakes,
raccoon and birds. All of these species
use the pond as a source of water and
many use it as their habitat.
Microscope Carry
microscopes by
the arm and base
Clean the ocular
lens and
objective with
lens paper only
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Microscope Place the slide on
the stage and
lower the
objective
carefully
Look from the side
when focusing
while looking
through the
ocular lens and
raising the
objective lens
Microscope Lower the stage
before changing
from a lower
objective lens to
a higher
objective lens
Watch from the
side of the
microscope to
ensure that the
objective does
not hit the stage
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Microscope Use the diagram
to help identify
the various parts
of the
microscope
When using a
microscope,
always ensure
that the
magnification is
on the lowest to
start
Micro-organisms
Working in groups, we will be baking
bread.
Half the groups will be using the recipe as written
Half the groups will be using the recipe without yeast
Examine yeast under a microscope
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Micro-organisms
Mould is a micro-organism also.
Help devise a set of experiments to
determine what bread mould needs to
grow and reproduce.
Remember to test only one variable at a
time.
The Roles of micro-organisms
Help to fill-in a t-chart comparing the
“Beneficial Roles” and the “Harmful Roles”
Select one item from the chart to
research
Use the research findings to prepare an
information poster, to be posted on the
class bulletin board
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Food Preservation Techniques
Refer to cookbooks, family and/or friends to identify past and present methods tofpreserving foods.
List the different food preservation techniques and indicate which of a micro-organism’s basic needs is affected by each preservation technique.
Record information in a chart and share it with the class.
The Barbeque
What’s the cause?
List all the food practices contained within the barbeque scenario and indicate whether they were safe.
Use this information to identify and explain a possible cause for the illnesses, including an explanation of why Harry was extremely ill while Alice did not succumb to the illness her friends did.
