Biology Form 4 Chapter 9 - 9.1 Endangered Ecosystem

1. BIOLOGY FORM 4
CHAPTER 9
9.1 ENDANGERED ECOSYSTEM

2. Topic deals with how humans affect
the environment
IInn aa nneeggaattiivvee wwaayy
IInn aa ppoossiittiivvee wwaayy

3. EENNDDAANNGGEERREEDD EECCOOSSYYSSTTEEMM
Effects of unplanned
development and
mismanagement of
the ecosystem
Greenhouse effect
and thinning of the
ozone layer
Proper management of
development activities
and the ecosystem
• Soil erosion
• Flash flood
• Landslide
• Eutrophication
• Global warming
• Ozone depletion
• Climate change
• Extinction of living things
• Deforestation
• Pollution
• Cause and effect
• Impact on ecosystem
• Implementation of laws
• Use of technology
• Education on the
management of resources
• Preservation and
conservation of soil, water,
forests and mangrove
swamps
• Practice of biological
control
• Use of renewable energy
• Efficient use of energy
Sources of
pollution
Effects of
pollution
• Air
• Water
• Thermal
• Noise
• Human health
• Habitat of animals and plants
• Buildings
• Agriculture
• climate
Types of pollution

4. Effects of Unplanned Development and
Mismanagement of the Ecosystem
Soil erosion
Flash floods
Acid rain
Climatic changes
Green house effect
Ozone depletion
Species extinction
landslides
Deforestation
Eutrophication
Air Water
Pollution
Sound Thermal

5. HARMFUL EFFECTS OF HUMAN
ACTIVITY CAN LEAD TO

6. Extinction is when a species no longer
exists
Species: a group of organisms that are able to interbreed and
produce fertile offspring.

7. An increase in human population
affects the environment in 3 ways:
11..AAggrriiccuullttuurree
22..HHoouussiinngg
33..IInndduussttrriieess

8. 1. Intensification of agriculture
 forests are cut down to plant crops

9. 1. Intensification of agriculture
 Pesticides and fertilisers are applied

10. How do
pesticides and
fertilisers end
up in the sea?

11. 2. Urbanisation
 land is lost to build towns

12. 2. Urbanisation
 problems in refuse and sewage disposal
 disease may result

13. 2. Urbanisation
 burning of fossil fuels for:
 heating & transport pollute
the air

14. Fossil fuels are:
ccooaall ooiill
Natural gas
[methane is
major
component]

15. 3. Industrialisation
 more factories
more pollution

17. Soil erosion means that soil is:
or

18. Three causes of soil erosion:
1. deforestation
– cutting down of trees

19. Three causes of soil erosion:
2. bad farming methods
– crop rotation not used
– heavy use of artificial fertiliser

20. 3. Overgrazing
– herbivores are
allowed to graze
very often in the
same field

21. Soil erosion leads to:
desertification
:the land cannot bbee uusseedd ffoorr aaggrriiccuullttuurree

22. Three ways to reduce soil erosion:
1. contour ploughing - ploughing around hill
instead of up-down
Ploughing vertically
increases soil erosion.
Contour ploughing
reduces soil erosion.

23. Water settles in furrows.

24. 2. strip cropping
alternate strips of crops are planted in the same field

25. Crops are planted:
2. at right angles
to the wind
direction.
1. following the natural
contours of the land.

26. 3. terracing

28. Why are trees cut down?
1. to clear the land to build houses, roads and
factories
2. to convert the forest into agricultural land
3. to use the wood from trees as a fuel
4. wood is used as a building material

29. 5 harmful effects of deforestation:
1. Imbalance in the water cycle
 less rain forms
in deforested
areas due to
less
transpiration

30. 2. Has a severe impact on soil
– roots & leaves no longer protect the soil.

31. 3. Drives countless plant
and animal species to
extinction – due to loss of
habitat and food.
Loss of biodiversity

32. Biodiversity: the
variety of life on Earth
MMoonnooccuullttuurree::
LLOOWW bbiiooddiivveerrssiittyy
FFoorreesstt::
HHIIGGHH bbiiooddiivveerrssiittyy

33. 4. CO2 levels rise, contributing
to the greenhouse effect
(global warming).

34. 5. A valuable natural source is wasted e.g. seeds, fruit,
rubber, resins
rubber
resin

35. Explain the poster.
How can trees be saved?
RReeccyyccllee
ppaappeerr

36. 5. A valuable natural source is wasted e.g. medicinal
compounds.

37. Afforestation:
the planting of trees

38. Question:
Give a biological explanation for each of the
following statements:
It is estimated that deforestation will increase
in the coming years. (3)
Human population is estimated to increase.
Forests are cleared to make way for houses,
roads , factories and to grow crops.
Trees are cut as a source of wood as fuel or
building material.

39. Question:
Give a biological explanation for each of the
following statements.
If trees are cut down in an area, there will be a
reduction in the bird population. (3)
Birds lose their natural habitat and source of
food.
They sleep on the branches, hide from
predators and seek shelter on trees.

41. Pollution
 is any process which leads to a
harmful increase in the amount
of a chemical substance in the
environment

42. Pollutants are harmful
 Pollutants can
be:
 substances
 energy
Light pollution
Noise pollution

43. Four types of
pollution:
1. Air
2. Water
3. Land
4. Noise

44. The Air Quality Index
Air Quality Index (AQI)
Values
Levels of Health
Concern
151 to 200
201 to 300
301 to 500
Unhealthy
Very Unhealthy
Hazardous
0 to 50
51 to 100
101 to 150
Good
Moderate
Unhealthy
for Sensitive Groups

45. Air pollution:
 Lead
 Chlorofluorocarbons [CFC’s]
 Carbon dioxide & carbon monoxide
 Oxides of nitrogen & sulfur dioxide

46. Air pollution:
 LLeeaadd
 Chlorofluorocarbons [CFC’s]
 Carbon dioxide & Carbon monoxide
 Oxides of nitrogen & sulfur dioxide

47. Lead
 Leaded petrol:
 lead - antiknock
 lead ends up in air from car
exhaust
 Lead harms the brain & liver of young
children
 Most cars now use unleaded petrol.

48. Question:
Give a biological explanation for each of the
following statements.
Most cars now run on unleaded petrol and
leaded petrol is becoming less readily
available. (5)
Most cars run on unleaded fuel because lead
compounds in fuel are absorbed into the body
from inhaled air and may slow down mental
development and damage the liver.

49. Air pollution:
 Lead
 CChhlloorroofflluuoorrooccaarrbboonnss [[CCFFCC’’ss]]
 Carbon dioxide & Carbon monoxide
 Oxides of nitrogen & sulfur dioxide

50. Chlorofluorocarbons (CFC’s)
 liquefy when compressed
 were invented in 1928 – very
unreactive
 some CFC’s have a lifespan of up to
75 years!
 used as refrigerants, propellants in
aerosol cans and in making plastic
foams

51. CFC’s destroy the ozone layer (O3)

52. Role of the ozone layer:
absorbs UV rays

53. Air pollution:
 Lead
 Chlorofluorocarbons [CFC’s]
 CCaarrbboonn ddiiooxxiiddee && CCaarrbboonn
mmoonnooxxiiddee
 Oxides of nitrogen & sulfur dioxide

54. Burning of fossil fuels produces:
 SOOT:
 Blackens buildings
 Reduces
photosynthesis
 Causes irritation of
lungs

55. Air Pollution Reduces Visibility
Acadia National Park
• A Clear Day vs A Hazy
Day

56. Carbon dioxide is
 released when burning fossil
fuels
 a greenhouse gas
 contributes to the
greenhouse effect

57. Carbon monoxide
 combines with haemoglobin
instead of oxygen
 Result:
 less oxygen in blood

58. Air pollution:
 Lead
 Chlorofluorocarbons [CFC’s]
 Carbon dioxide & Carbon monoxide
 OOxxiiddeess ooff nniittrrooggeenn && ssuullffuurr
ddiiooxxiiddee

59. Sulfur dioxide and oxides of nitrogen
 form on burning fossil fuels
 the gases dissolve in rainwater and form ACID
RAIN

61. Acid rain has many harmful
effects

62. Effects of Acid rain:
 dissolves limestone

63. Effects of Acid rain:
 reduces the growth of
plants and damages leaves

65. Effects of Acid rain:
 makes lakes acidic, killing
fish and invertebrates

66. Question:
A recent study showed that the water in the
river is acidified.
A characteristic feature of acidified water in
rivers is the slow rate of decomposition of
organic matter. Explain. (3 marks)
Decomposers like bacteria function best at an
optimum pH. At an acidic pH, decomposition
occurs slowly.

67. Effects of Acid rain:
 dissolves out nutrients, leaving the soil
infertile

69. Question:
Give a biological explanation for each of the
following statements.
Many industries are using sulfur-free fuel. (5)
Sulfur-free fuel reduces the emission of sulfur
dioxide in the atmosphere; thus this reduces
the risk of acid rain caused by sulfuric acid and
other acids.

70. To reduce pollutants in air, cars are fitted
with: 11.. FFiilltteerrss –– ddiieesseell eennggiinneess

71. 22.. ccaattaallyyttiicc ccoonnvveerrtteerrss –– ppeettrrooll eennggiinneess
Normal exhaust consists of:
 unburnt petrol
 carbon monoxide
 oxides of nitrogen
The catalytic converter causes a reaction between these badly
polluting exhaust gases to produce harmless gases which
include:
 nitrogen
 oxygen
 carbon dioxide
 water vapour

72. To reduce pollutants in air,
chimneys are fitted with
filters

74. Renewable & Non-renewable
 renewable energy sources:
 can be replenished (made again) naturally
[e.g. solar and wind energy]
 nonrenewable energy sources:
 cannot be replenished in a short period of
time[fossil fuels]

75.  Clean energy

76. Non-renewable energy
 Cause of air pollution

77. Solar energy
Wind energy

78. Water pollution:
 Sewage
 Fertilisers
 Pesticides
 Oil spills
Raw sewage: Bangkok

79. Sewage
 may contain bacteria which
cause cholera and typhoid
 if the bacteria enter drinking
water the disease spreads to
many people

80. Sewage & fertilisers :
 contain nitrates & phosphates
 both cause:
the enrichment of natural waters with
nutrients which allow great growth of algae

81. Plants need
nitrates &
phosphates to
produce proteins
More proteins
=
More growth

82. Eutrophication
Leaching of inorganic fertilisers / input of untreated sewage / run off
animal waste
Increase in mineral nutrients(nitrates & phosphates) into bodies of water
Algae bloom (rapid growth of algae)
Restricts the penetration of light into the water
Death of other aquatic photosynthetic plants and algae
Decomposition by bacteria (rapid growth of bacteria)
Bacteria use up oxygen
BOD level increase
Aquatic organisms die

83. B.O.D.
(Biochemical Oxygen Demand)
• Refers to amount of oxygen consumed by
aquatic organisms per litre of water.
• ↑ B.O.D. ↑ water pollution

84. Algal bloom
Satellite image

85. Eutrophication

87. Dead fish in China [2010]

89. Question:
Give a biological explanation
of the message in the poster:
Eutrophication leads to algal
blooms. Algae die and are decayed
by bacteria. Bacteria use oxygen
from the water, causing fish and
other aerobic organisms to die.

90. Sewage at Mellieha [2009]

91. Is there a way to make sewage safe to
pour into the sea?
Use a sewage treatment plant.

92. Saprophytic bacteria in sewage treatment plants
remove harmful nutrients from raw sewage
AAnn aaeerriiaall vviieeww ooff tthhee GGoozzoo
sseewwaaggee ttrreeaattmmeenntt ppllaanntt

93. Fig. 6 A sewage treatment plant.
Sludge: solid part
Effluent: liquid part

94. FFiirrsstt sseettttlliinngg ttaannkk

96. Sludge may be:
 dumped into the
sea
 dried for fertiliser
 fermented to make
methane gas

97. What happens to the effluent?
EFFLUENT
sea
irrigation

98. Water from sewage treatment used
for plant irrigation

99. Water pollution:
 Sewage
 Fertilisers
 Pesticides
 Oil

100. Fig. 7 How fertilisers reach the
groundwater.
runoff

101. To avoid contamination of ground-water:
i) use natural fertilisers as these are less
soluble
ii) do not over-apply fertiliser

102. Water pollution:
 Sewage
 Fertilisers
 Pesticides
 Oil

103. Pesticides are chemicals that kill pests

104. Pesticides can be:
1. Persistent:
 remain active for a long time after they
have been released e.g. DDT
2. Non-persistent:
 break down in the environment soon after
they have been released

105. Harmful effects of pesticides:
1. Can kill beneficial organisms.

106. 2. Can build up along the food
chain, killing the top carnivore.

107. 3. Causes water pollution.

108. 4. Causes insects
to become
resistant to
the pesticide.

109. DDT & dieldrin are now banned from
most countries

110. What is ‘organic food’?
Food that is produced using methods that do
not involve pesticides and chemical fertiliser.

111. We can get rid of pests by:
1. Chemical control:
spray with chemicals
2. Biological control:
making use of other organisms which kill the
pest

112. Examples of biological control
Fig. 9 Wasps are used to kill caterpillars.

114. Ladybirds feed upon aphids
(greenflies)

115. Guppy fish eat
mosquito larvae

116. Biological control gone wrong:
Cane toads in Australia

117. Advantages of biological control:
1. it avoids polluting the environment
2.pests never develop resistance to it

118. Disadvantages of biological control:
1. the introduced organism dies out as
the environment does not suit it
2. the control agent may eat up all the
pests and then starts eating a
useful species

119. Water pollution:
 Sewage
 Fertilisers
 Pesticides
Oil

120. Oil spillages from tankers cause harm

121. What is the effect of an oil spill on
birds and fish?

122. Birds die: too heavy to fly

123. Fish die: gills become clogged with oil
Dead fish in a clump
of oil [2010]

124. Beaches are spoilt

125. Seashore animals & plants become
covered with oil

126. WWhhaatt aabboouutt
ppllaassttiicc aatt sseeaa??

127. Plastic in the sea harms animals

129. Land pollution:
3. Land pollution:
dumping of rubbish

130. Waste Management involves:
 the collection and transportation of materials from
households, businesses, schools and so on, to be
processed or disposed of

131. Landfill is the most common method
of waste disposal all over the world
Landfill involves
dumping waste in
unused/unwanted
sites such as
disused quarries

132. In order to fit more in:
 rubbish in landfill sites is regularly squashed
 soil is added – why?
1. To reduce
odour
2. Prevent
lightweight
waste from
becoming litter

133.  this squashing, removes air which leads to
the landfill becoming anaerobic (without air)
 methane gas is produced

134. What can be done for a landfill to
take long to become full?
 Burning
 Compressing
 Extracting certain materials for reuse

135. Remember the 3R’s with regards to
waste management

136. Some landfill sites are engineered
 To capture methane
 methane is used to
generate energy

137. What is an ‘engineered landfill’?
 landfill is lined with plastic to prevent
leaching

138. Plastic lining at a landfill

140. 1. Rotting rubbish emits explosive gases
and polluting liquids.

141. Toxins leach out of the landfill &
contaminate the sea

142. 2. Visual pollution

143. 3. Rotting rubbish:
 produces an odour
 encourages pests

144. Question:
Discuss the environmental disadvantages of:
dumping of rubbish. (3)
Dumping sites have an impact on the surroundings
– unsightly rubbish and impact of smells; dumping
sites can attract pests such as flies and rats and
these spread disease; damage to air pollution
from possible burning of items; ground water and
run off pollution; habitat destruction.
Accept any reference to dumping in the
sea/nonbiodegradable rubbish

146. Human hearing and Frequency
0 16 Hz 20 kHz 5 MHz

147. Typical suburban sound and their levels

148. Major transportation sources of
noise pollution: rail, road, and air

149. Types of Pollution
Noise pollution
• Excessive noise (>55dB)
• Source: Vehicles, air crafts, machines,
construction sites, traffic.
• Effect: Hearing problem, ear injury,
headaches, emotional & mental disturbances,
high blood pressure, deafness.

150. Question:
Give a biological explanation for each of the
following statements:
Human activities can lead to extinction in many
ways. (5)
Extinction is when a species does not exist any
more.
Humans destroy the natural habitat of plants and
animals by:
cutting down of trees
overhunting and overfishing
changing the climate due to global warming

151. Question: SEP, 2009
Give a biological
explanation for each of
the following statements:
Shipping adds pollutants
to oceans. (3)
Ships may release raw
sewage into the ocean.
Tankers may accidentally
spill oil.
People on ships may dump
plastic or other solid
waste.

152. TTHHEE EENNDD
OOFF 99..11