Environment and Energy
Vocabulary
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Biotic
Abiotic
Ecosystem
Consumer
Producer
Decomposer
Autotrophs
Heterotrophs
Biomagnification
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Bioaccumulation
Biomass
Photosynthesis
Non-Renewable
Renewable
Fossil Fuels
Geothermal
Hydroelectricity
• 5.10a) distinguish between biotic and abiotic features of the
local environment
• 5.10b) describe the importance of cycles of materials in
ecosystems
• 5.10c) describe some impacts of human activities on
ecosystems
• 5.11.1a) discuss the importance of energy as a resource
• 5.11.1b) identify properties that make some natural resources
economically important and describe their uses
• 5.11.2a) relate pollution to contamination by unwanted
substances
• 5.11.2c) discuss strategies used to balance human activities
and needs in ecosystems with conserving, protecting and
maintaining the quality and sustainability of the environment
• 5.12b) discuss the benefits and problems associated with
medical and industrial uses of nuclear energy
What is energy?
• Energy is the ability to do work and is
measured in joules (J). Organisms
require energy for the ‘work’ of living.
• This work includes growth,
reproduction, respiration, repair of
body tissues and digestion.
Recall
• Consider this simple food chain
green plant →insect→frog→snake→kookaburra
• Here, we can see that the energy from the
green plant (a producer) goes into the insect
(a primary or 1st consumer), which then
provides energy for the frog (a secondary or
2nd order consumer).
•The frog is a source of energy for the
snake (tertiary or 3rd order
consumer), which in turn provides
energy for the kookaburra (4th order
consumer).
• In this food chain, the kookaburra is the
highest order consumer, as it is unlikely that
anything else will be able to catch and eat it.
•If by chance a dingo or some
other animal caught it, that
animal would be considered a
fifth order consumer.
Plants
• Convert light energy into chemical energy
(Photosynthesis). Organisms that produce
food in this way are referred to as
producers or autotrophs. All other
organisms rely on the energy stored by
plants to meet their energy needs.
• Organisms that eat plants are referred to
as consumers or heterotrophs. In the
food chain, energy is not the only thing
being transferred from one organism to the
next—matter is also being transferred.
•Most of this
material is used
directly by the
next organism for
its growth and
survival, some is
lost to the
environment as
waste products or
heat.
Food pyramids
• Consider this summarised food chain;
producers (plants) →herbivores →carnivores
• There are vast numbers of plants. We would
expect to find a smaller number of
herbivores eating those plants and an even
smaller number of carnivores eating the
herbivores.
• In any ecosystem the number of individuals
at each level decreases as we move from
the producers up to the higher orders of
consumers. A food pyramid shows the
mass of organisms change and that the
total amount of energy at each level
decreases.
•If we were to gather all the producers,
herbivores and consumers in a food chain,
and represent either their numbers or their
dry weight diagrammatically,
we would expect a
pyramid-shaped
diagram.
Pesticides and herbicides
• Crops have been a readily available source of food for
many insects and pests. The use of fertilisers and
ploughing of the land has also encouraged weeds to
grow among the crops. Both weeds and animal pests
are known as competitors.
• Humans have developed chemicals to control these
pests, called herbicides and pesticides.
• Herbicides kill pest plants or weeds, while pesticides
kill animal and insect pests.
Biomagnification.
• With use, these chemicals have
become part of the natural food
chains. The chemicals are absorbed
by plants and small animals.
• When these plants and animals are
consumed by other animals, the
chemicals are also consumed and
passed up the food chain.
• Chemicals also wash into rivers, lakes
and the ocean, where they are
absorbed by algae. The algae are
consumed by aquatic animals and
again the chemicals are passed up
the food chain.
• This is called Biomagnification.
Bioaccumulation
• Is the process of organisms
accumulating (building up)
higher and higher levels of
these chemicals in their
bodies.
• These chemicals become
more concentrated in
organisms as we move up a
food chain. Animals at the
top of the food chain must
consume very large
amounts of other organisms,
and so more and more
chemicals become
concentrated in their tissues.
Problems include:
• the deaths of many large
sea mammals such as
dolphins and whales,
which is thought to be
related to bioaccumulation
• the thinning of egg shells of
birds such as the
American eagle, leading to
this animal becoming
endangered
• increased rates of cancer,
disease and deformities in
humans
The concentration of chemicals in a food
chain is shown by this energy pyramid.
Recycling in Nature
• Dead organisms are returned to the
ecosystem by the action of decomposers
• Decomposition involves the breakdown of
organic materials, releasing the required
nutrients to the air,
water and soil. Two
important elements that
are recycled are carbon
and nitrogen.
• Organic matter basically means containing
Carbon, and is found in all living things.
• Inorganic matter does not contain carbon
and includes simple substances such as
water, minerals and glass.
Natural Cycles
• All cycles rely on the flow of atoms between
the biotic (living) and the abiotic (non-living)
environment. In healthy ecosystems, this flow
remains balanced.
• An Abiotic environment for a fish
would include coastal currents,
tides, temperature, water
salinity, and chemicals added by
human activities.
• Its Biotic environment would
include the organisms on which
it feeds, or those which compete
for food and space, and those
which may feed on it.
• All these environmental factors
influence the survival of the fish.
The water cycle
• Of all the water on Earth,
almost 98% is found in the
salt water of the oceans.
• Of the remaining 2%, some
is found in the form of
atmospheric water vapour
and as permanent ice
deposits in various parts of
the Earth.
•Less than 1% is available as fresh water to
the organisms that live on the Earth.
•It is only because water is recycled that life
on our planet has been able to exist for
millions of years.
•The Sun is the only
source of energy that
powers the essential
process that we know
as the water cycle.
Heat energy from the Sun
causes water molecules to
evaporate from:
• moist soil surfaces
• living organisms such as plants (by
transpiration) and animals (sweat)
• lakes, rivers and oceans.
• Of these, evaporation from the oceans provides most
of the water vapour present in our atmosphere.
• Carried by air currents, much of the water vapour falls
as either rain or snow when it reaches land. Eventually
the water finds its way back to the sea, allowing the
cycle to continue.
The carbon cycle
• Carbon is found in all living
things, and in our atmosphere
as CO2. It is the movement of
carbon atoms between the
living and the non-living
environment that we call ‘the
carbon cycle’.
• In our biosphere, land plants
take up the carbon dioxide
directly from the atmosphere
through tiny pores in their
leaves called stomata, while
aquatic algae absorb carbon
dioxide, dissolved in the
water surrounding them, over
their entire surface.
• Once inside the plant, the carbon atoms detach
from their oxygen atoms and rearrange to form
glucose (photosynthesis). Glucose is used for
energy or further rearranged into cellulose (a
structural component in plant cell walls) and
starch (an energy store).
• Photosynthesis: is driven
by energy from the Sun. It
is the process that
provides the foundation
for most of life on Earth.
• Herbivores eat and digest
plant matter, using the
carbon and other elements
contained within the plant to
provide for their own energy
and growth. Higher order
consumers rely on digestion
to convert the carbon
obtained from eating animal
or plant tissue into a form
they can use. Carbon gets
back to the atmosphere by
• the release of carbon dioxide via respiration, which can
be summarised as:
• sugar + oxygen →water + carbon dioxide + energy
• Sugar breaks down to provide energy. Carbon dioxide
and water are waste products that are released back into
the ecosystem.
• • the return of carbon to the ecosystem through animal
wastes (faeces and urine) and the decomposition of
dead plants and animals and animal wastes by the action
of decomposers (bacteria, fungi and worms) in the soil.
• CARBON CYCLE.
• The balance of CO2 and
O2 is changing due to:
• • large-scale felling of
rainforest trees
• • increased production of
carbon dioxide by industry
• • increased burning of
fossils fuels such as
petrol.
• This imbalance is referred
to as the enhanced
greenhouse effect
• The nitrogen cycle
• Nitrogen makes up about
78% of the air around us.
Most organisms cannot
use nitrogen directly.
Before it can be used it
needs to undergo a
process called nitrogen
fixation. Most of this
happens during lightening
strikes, where the
electrical energy from the
storm converts
atmospheric nitrogen into
various useful nitrogen
compounds.
• One group of those compounds is the nitrates
(NO3). These dissolve in rain droplets and fall
onto the Earth’s surface, and are taken up by the
roots of plants. Once inside the plant, nitrogen
plays an essential part in the formation of amino
acids and nucleic acids (the building blocks of
genetic material).
• These nitrogen compounds are then consumed
by animals when the plants are eaten.
• Energy sources
• are classified as nonrenewable or renewable.
• Energy sources that cannot
be replaced are referred to
as non-renewable.
• These energy sources
include:
• • fossil fuels such as coal,
gas and crude oil.
• • uranium and other nuclear
fuels used in nuclear power
plants.
• Fossil fuels
• Coal forms from decaying plant material buried in swampy
areas under muds to prevent total decomposition. Over millions
of years the plants turn into coal from chemical changes caused
by heat and pressure. Oil and gas generally form from
decaying marine organisms buried in shallow seas over millions
of years.
• Uranium
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When uranium atoms are bombarded
with neutrons, they often split,
releasing more neutrons and
enormous amounts of energy. So
much energy, in fact, that splitting just
one uranium atom releases 26 million
times more energy than the burning of
one molecule of natural gas!
This process is referred to as nuclear
fission. Nuclear reactors were built to
produce energy however we have
problems of how to dispose of the
dangerous waste products.
Radioactive
waste can cause cell damage in living
organisms and lead to cancer. Many
methods of storing nuclear waste
have been tried in the past but all are
only short-term solutions.
The waste can remain radioactive for
many thousands of years.
• Renewable energy sources
• Renewable energy comes from
sources that can be used over
and over again with minimal
impact on the environment.
• Renewable forms of energy
include:
• • energy from the Sun
• • energy from the vast quantities
of heat stored within the Earth
• • energy from the action of wind
• • energy from water—the action of
waves, currents or tides, the
falling of water due to gravity, or
differences in salt content
• • ‘green energy’—energy derived
from wood and other plant matter
(sometimes called biomass).
• Energy from the Sun
• Solar ponds
• In a shallow pool, sunlight passes through
the water and is absorbed by the base and
sides of the pool, gradually warming them.
Water that is in contact with the sides and
base slowly gets warmer too. Warm water
rises and cool water drops, causing
• Convection currents throughout the pond.
These continue until the temperature of the
pond is uniform throughout. If salt is added
to the water, however, the warm water does
not rise, but stays warm at the bottom of the
pond. Water pipes running along the bottom
of
• the pond can be used as a way to heat
fresh water passing through the pipes.
• The temperature of the water at the bottom
of a solar pond can be as high as 107°C—
hot enough to turn special turbines to
generate electricity.
• Solar cells
• Solar cells convert light energy
into electrical energy.
• They are extremely useful in
remote areas because they
have no moving parts to service
and require no fuel except
sunlight. Unfortunately the
process used for the production
of solar cells is not energy
efficient and also produces
pollution.
• Recent research has led to the
development of a ‘solar
concentrator’—the Winston
tube. This instrument
concentrates light to intensities
similar to that of the Sun’s
surface, generating enormous
quantities of cheap, nonpolluting energy
Energy from within the Earth
(Goethermal)
• Some countries, such as New Zealand, have hot
magma very close to their surface because they
lie on fault lines in the Earth’s crust.
• They are able to use this geothermal energy to
produce electricity: water is pumped into the
ground, where it is heated by the molten rock
until it boils and produces steam. The steam is
tapped and turns turbines that produce electricity.
Although this system appears to be ideal, there
are some disadvantages:
• • Only countries near fault
lines have easy access to
molten rocks beneath the
surface.
• • When water is extracted
from or pumped into
rocks, underground
pressures change,
leading to increased
likelihood of earthquakes
and rock cracking.
• • Geothermal energy
produces a number of
gaseous pollutants,
particularly carbon
dioxide, hydrogen sulfide,
sulfur dioxide and
methane.
Geothermal energy is used in areas where
active volcanoes and lava lows are present,
or where water heated by deeply buried rocks
makes its way to the surface. Water can be
pumped down into the ground to be heated by
the hot rocks, then pumped back out again.
Australia makes only limited use
of geothermal energy
production.
The Mulka Cattle Station in
South Australia has used it
since 1987, and the Garden
East Apartments (also in South
Australia) have been operational
since 1994.
Funding has also been provided
for a pilot plant in the Hunter
Valley, New South Wales. In
contrast, New Zealand meets up
to 75% of its energy needs
through geothermal sources.
• Energy from the wind
• Global winds are the result of hot
air rising over the equatorial
regions. This process creates a
space into which cooler air from
the poles rushes. We call this
movement of air ‘wind’.
• Sailing boats and windmills have
used wind energy for thousands of
years. Now we have wind turbine
generators, they convert the
energy of wind movement into
electricity. This electricity is used
directly to do mechanical work, or
fed directly into the electricity grid,
or it can be stored in batteries for
later use.
• Factors that influence the amount of electrical energy
produced include:
• • the wind speed. The power supplied by the wind turbine
• generators depends on the wind speed cubed. Thus when
the
• wind speed doubles, the power produced increases eightfold.
• • the length of the blades. The power supplied is related to
the length of the blades squared. This means that when the
blade length is doubled, the power is quadrupled.
• At Blayney, west of Bathurst, New South
Wales, 15 turbines generate 10 MW of
power. This is enough power for 7000
homes and replaces older technologies that
would produced 16 000 tonnes of carbon
dioxide emissions yearly. The largest single
wind generator is on Kooragang Island,
Newcastle.
• Energy from water
(Hydroelectricity)
• Gravity pulls water downhill
until it reaches the lowest
possible point—the sea. The
gravitational potential energy
it contains can be harnessed by
passing it through turbines to
generate electricity.
• Electricity produced in this
manner is referred to as
hydroelectricity. There are two
ways we can maximise the
amount of electricity produced.
• • Make a small volume of water fall from a great
height.
• • Make a large volume of water fall from a much
smaller height.
• The largest hydroelectric scheme in Australia is the
Snowy Mountains Scheme in New South Wales,
which generates almost 3800 MW (megawatts) of
power. Consisting of 16 dams and 145 km of tunnels,
this series of seven power stations provides 50% of
Australia’s hydropower. A further 30% comes from
Tasmania.
Using water currents, tides, waves
and salinity
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Wave energy generators; Waves are forced into a narrow gully, causing the air
above them to rise and fall. This moving air passes
through a turbine to produce electricity.
Tidal power generation; place a barrier across a bay’s entrance so that the
incoming tide turns a turbine. At the maximum height of the tide, the water flow
is blocked until the tide is low. The stored water is then released at low tide
turning the turbine making more electricity.
An oscillating wave column (OWC); generates energy by using ocean waves.
The waves push air past a turbine, causing it to spin and as they recede they
suck air past the turbine causing it to spin again. This creates power in both
directions.
• Biomass
• Is the term used to
describe organic material
that has recently died
and which can be used to
generate energy. It
includes everything from
wood from fallen trees or
industrial processes to
the faeces from humans
and animals.
• Biomass can be used directly by burning it or by
collecting and burning the gases produced from
biomass decay eg methane.
• Indirect use of biomass involves converting it into
a suitable fuel. This most occurs with crops such
as sugar cane, corn, rice and wheat. Waste
products from their harvesting are processed into
fuels such as ethanol and biodiesel.
• Energy from industrial
and household waste
• The commercial food
industry produces vast
quantities of both solid
and liquid wastes.
• These wastes contain
dissolved organic matter,
including sugars and
starches, and have the
potential to produce
ethanol when combined
with certain anaerobic
bacteria.
• Of the total household waste collected each day,
more than 80% is biomass, and of this 46% is
organic matter (food scraps and garden waste).
This type of waste can be converted into energy
directly, by burning, or it can be ‘digested’ by
anaerobic bacteria in landfill gas plants to
produce biogas (methane and carbon dioxide),
which can then be used to generate heat and
power.
• Energy from animal and human
waste
• In many developing countries, the
manure from cows, camels and
other animals is shaped into
‘pancakes’ or ‘bricks’, dried and
stored.
• It is then burned to provide heat
mainly for cooking. Animal and
human wastes can also be
converted to biogas using anaerobic
bacteria.
QUESTIONS…
• 1 a Identify how energy resources
• 10 State the benefits of using
are classified into two major types.
wind-powered electricity
generators.
• b List examples of each type.
• 11 a Propose a likely meaning for
• 2 Define the term ‘fossil fuel’.
the term ‘wind farming’.
• 3 Define the term ‘nuclear fission’
• b Discuss the advantages and
and explain why some think it is a
disadvantages of this form of
desirable energy source.
energy production.
• 4 Discuss two disadvantages of
• 12 List the various ways in which
nuclear energy.
we would water can be used to generate
• 5 List three ways we use energy
electricity.
from the Sun.
• 13 Define the term ‘biomass’.
• 6 State the two major benefits of
• 14 Explain two ways in which
using the Sun as an energy
biomass can be used to supply
source.
energy.
• 7 Define the term ‘geothermal
• 15 Describe how fossil fuels are
energy’.
produced.
• 8 Describe how geothermal
• 16 Your friend cannot understand
energy is used to produce
why coal and gas are called ‘fossil
electricity.
fuels’. Explain to him why these
• 9 Discuss two disadvantages of
terms are being used correctly.
geothermal energy.