Sustainable Ecosystems
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All organisms require energy to stay alive and function
The source of all of this energy is radiant energy
This is the energy radiated from the sun
About 70% of the radiant energy is absorbed by the
hydrosphere and lithosphere and converted into
thermal energy
Thermal energy is what warms the atmosphere,
evaporates water, and produces winds
 About 30% of the radiant energy from the Sun is
reflected back into space
 A very small amount of the radiant energy that
reaches Earth’s surface is absorbed by living
organisms
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Copy into your
definitions
SOLAR ENERGY
- Source of almost all energy
needed by organisms to
live/function
- 70% absorbed (warms the
atmosphere, evaporates water,
produces winds…)
- 30% reflected back into space
All organisms need energy to live
and grow, but not all energy works
in the same way
 Thermal and radiant energy do not
directly give organisms all they
need to live and grow
 Energy from the Sun must first be
converted into a form that can be
used by living things – chemical
energy
 Chemical energy can be stored in
living things and used as needed
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Note!
- Some organisms absorb light
energy to make their own
chemical energy.
- Other organisms absorb
chemical energy from the food
that they eat
- Chemical energy is used by all
organisms to perform functions
which include movement,
growth and reproduction
- As chemical energy is used, it
must be replaced
CHEMICAL ENERGY
- Form of energy that can be stored in cells and
released when needed
- Used for life functions (movement, growth,
reproduction…..)
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Understanding the complexity of ecosystems
may be one of science’s greatest challenges
The first step toward understanding were
made when early scientists began to
investigate the relationship between plants
and animals
In the 18th century, Joseph Priestly performed an
experiment with candles, a mint plant and two
sealed jars
 In this case, he discovered that the candle in jar A
burned for 3 minutes while the candle in jar B burned
for 5 minutes
 Priestly’s experiment clearly showed that the plant in
jar B was producing an invisible gas that supported
burning
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In a second experiment, Priestly used mint plants,
mice, and three sealed jars
 While both mice eventually died  , he discovered
that the mouse/plant combination in jar E lived longer
 Priestly’s second experiment clearly showed that
plants and animals do help each other
 However, it wasn’t until later that scientists
discovered the connection
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As you are aware, many organisms
are able to convert light energy into
chemical energy using the process of
photosynthesis
 This conversion of energy is one of the
most important chemical processes
 Without it, most life on Earth would
not exist
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carbon dioxide + water + light energy  sugar + oxygen
Note!
- An organism that makes its own
food is called a producer
- Plants are producers
- Chlorophyll, which gives plants their
green colour, captures light energy
- The light energy is then used to
convert carbon dioxide into glucose
(sugar) which is stored in the plant
PRODUCER
- Organism that makes its own energy
- Link the abiotic and biotic world
- Most plants, algae ……
…..What does the second statement above
mean??
Plants trap light energy from the sun (abiotic) and store
it in their body (biotic) which then consumers eat
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These sugars contain the stored chemical energy
During the process, the plant also releases
oxygen into the air as a by-product
Virtually all of the chemical energy contained in
food was once light energy captured during
photosynthesis
NOTE!
- Not all of the sugar produced through photosynthesis
goes toward energy storage
- Some sugars are used as building materials in the
plant (such as cellulose in cell walls)
PHOTOSYNTHESIS
- Process in which the Sun’s energy is converted
into chemical energy
- Without it, most life on Earth would not exist
carbon dioxide + water + light energy  sugar + oxygen
Video/photosynthesis song:
http://www.youtube.com/watch?v=C1_uez5WX1o
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When you breathe, it is the oxygen gas in the
air that keeps you alive
About 21% of the atmosphere is made of
oxygen, and almost all of it was produced
through photosynthesis
Both trees and algae in Earth’s
terrestrial and aquatic ecosystems
produce most of the world’s
oxygen
Unlike producers, which can make their
own energy through photosynthesis,
humans are consumers and need to
obtain energy from other sources
 Consumers obtain energy by eating
other organisms – producers, consumers
or their products
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CONSUMERS
- Organism that obtains their energy by
consuming other organisms, or their
products
So the food you eat contains
stored energy and when you
digest the food the energy in the
food is released through a process
called cellular respiration
 During this process, the sugar
combines chemically with oxygen
from the air and is changed into
carbon dioxide and water
 Cellular respiration looks almost
like the reverse of photosynthesis!!
 As this change occurs, energy is
also released
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NOTE!
- While the plant releases some
of the oxygen gas it produces
into the atmosphere, it uses the
rest of it to extract the energy
from the sugars it produces
- The plant then uses the energy
for the processes occurring
within its cells
CELLULAR RESPIRATION
- reverse process of photosynthesis
- Used to provide energy to the cell for life
functions (growth, ….)
sugar + oxygen  carbon dioxide + water + energy
Remember photosynthesis?
carbon dioxide + water + light energy  sugar + oxygen
NOTE!
- Photosynthesis and cellular
respiration involve the same
chemicals – water, carbon
dioxide, oxygen and sugar.
- Both processes also involve
energy
- But the reactions are the
opposite of each other and
produce different products
For example, while
photosynthesis produces
sugars that contain
stored energy, cellular
respiration uses the
sugars and releases the
stored energy so that it
can be used for life
functions
 Thus, the reason that
they are referred to as
complimentary
processes – both
processes need to
happen in order to
sustain life
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Write this down!
1.
Why are photosynthesis and cellular respiration
considered complimentary processes?
2.
What important substances do plants produce during
photosynthesis? How do humans use these substances?
3.
How do (i) produces and (ii) consumers get the chemical
energy they need to live and grow?
4.
Since plants can capture the energy of sunlight in
photosynthesis, why do they need cellular respiration?
**more on next slide
5.
Suppose a plant could perform photosynthesis
but it lost the ability to perform cellular
respiration. Explain what would happen to the
plant and why.
6.
Consumers are unable to make their own
energy, yet they obtain energy when they eat
animal food products. Explain how this
illustrates the flow of energy through an
ecosystem
1.
Why are photosynthesis and cellular respiration considered
complimentary processes?
The reactions are the reverse of each other and both processes need to
happen in order to sustain life
2.
What important substances do plants produce during photosynthesis?
How do humans use these substances?
oxygen & sugar – breathing & energy
3.
How do (i) produces and (ii) consumers get the chemical energy they
need to live and grow?
Producers – sun and soil
consumers – producers, consumers and their products
4.
Since plants can capture the energy of sunlight in photosynthesis, why
do they need cellular respiration?
to extract the energy from the sugars they produce – need the energy
for cellular processes
**more on next slide
5.
Suppose a plant could perform photosynthesis but it
lost the ability to perform cellular respiration.
Explain what would happen to the plant and why.
the plant would die – it need cellular respiration in
order to extract the energy from the sugars it
produces (for cellular respiration)
6.
Consumers are unable to make their own energy,
yet they obtain energy when they eat animal food
products. Explain how this illustrates the flow of
energy through an ecosystem
energy from the sun is captured by the plant which is
then passed onto the consumer
TEXTBOOK
- Page 35
- # 2, 12, 14
Activity: “From Land to Mouth”