2. Topic deals with how humans affect
the environment
In a negative way
In a positive way

3. HARMFUL EFFECTS OF HUMAN
ACTIVITY CAN LEAD TO

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

5. An increase in human population
affects the environment in 3 ways:
1.Agriculture
2.Housing
3.Industries

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

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

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

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

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

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

12. Fossil fuels are:
coal oil
Natural gas
[methane is
major
component]

13. 3. Industrialisation
 more factories
more pollution

15. Soil erosion means that soil is:
blown away by
the wind or
washed away by
rainwater

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

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

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

19. Soil erosion leads to:
desertification
:the land cannot be used for agriculture

20. 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.

21. Water settles in furrows.

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

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

24. 3. terracing

25. Is it a good idea to build
a brick wall instead of a
rubble wall?
no

26. Why do farmers quickly rebuild
rubble walls after damage by
rain?

28. Monoculture is when one type of
crop is grown over a large area

29. Advantage of monoculture:
 land can be used intensively, that is more
food for more people

30. Disadvantages of monoculture:
1. trees had to be cut
down so the natural
environment is
destroyed;
biodiversity is reduced

31. 2. repeated ploughing and the use of artificial
fertilisers damage the soil

32. 3. a pest spreads quickly as plants are close
together and natural predators are killed by
pesticides.

33. Question: SEP, 2008
Monoculture is a farming method that involves
growing one type of crop over a large area.
Suggest TWO negative effects of this method
on the environment. (4 marks)
1. Favours spread of pests that thrive on the
crop plant.
2. Reduces biodiversity (directly or indirectly)

35. 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

36. 5 harmful effects of deforestation:
1. Imbalance in the water cycle
 less rain forms
in deforested
areas due to
less
transpiration

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

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

39. Biodiversity: the
variety of life on Earth
Monoculture:
LOW biodiversity
Forest:
HIGH biodiversity

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

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

42. Cellulose can be used to make threads.
Threads are woven into cloth.
Cellulose
Dress made of
viscose.
Mop made
of viscose.

43. Explain the poster.
How can trees be saved?
Recycle
paper

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

45. Afforestation:
the planting of trees

46. Question: SEP, 2009
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.

47. Question: SEP, 2010
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.

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

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

51. Three types
of pollution:
1. Air
2. Water
3. Land

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

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

54. Lead
 Leaded petrol:
 lead - antiknock
 lead ends up in air from car
exhaust
 Lead harms the brain & liver of young
children
 Malta stopped using leaded petrol in Jan 2003
and lead replacement petrol (LRP) in Jan 2011

55. Question: MAY, 2011 (2B)
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.

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

57. 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 plastic foams

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

59. Role of the ozone layer:
absorbs UV rays

60. Chlorine in CFC’s
changes:
ozone into oxygen
and keeps on doing
this

61. What happens if the ozone layer is
destroyed?
Solar UV rays Solar UV
rays

62. Destruction of the ozone layer:
1. leads to increased
ultraviolet radiation
which:
 causes skin cancer
 damages plants
2. interferes with the O2
cycle
3. distorts weather patterns
Increase in ozone
hole over the
years.

63. To avoid damage by CFC’s:
1. use ozone-friendly
products
2. ban of products
containing
substances that
damage the ozone
layer

64. Question: MAY, 2011 (2B)
Give a biological explanation for each of the following
statements.
In many countries aerosols containing
chlorofluorocarbons (CFC’s) have been reduced. (5)
CFCs are very unreactive compounds that spread
through the atmosphere without reacting with other
substances and drift into the upper atmosphere. There
they meet ozone that oxidises CFCs and in doing so is
converted into oxygen. This is causing thinning of the
ozone layer that protects animals and plants from
ultraviolet radiation.
Thus countries are taking measures to reduce the use of
CFCs.

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

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

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

68. Air warms up
inside a
greenhouse

69. The Greenhouse Effect
Some sunlight that hits the earth
is reflected. Some becomes heat.
Some sunlight that hits
the earth is reflected.
Some becomes heat.
Greenhouse gases in
the atmosphere trap
heat, keeping the air
warm.

70. The greenhouse effect

71. Methane is also a greenhouse gas

72. Ice melts as
temperature
rises
 some animals lose
their habitat

73. How can a rise in air temperature be:
1. helpful to plants?
 Higher rate of photosynthesis
2. harmful to plants?
 Lose water and wilt.

74. Mention 4 ways of how release of
greenhouse gases can be reduced
from passenger vehicles

75. 1. Increase number of car-free
days
2. Use public transport

76. 3. Encourage car-sharing

77. 4. Encourage people
to use the bicycle.
- provide lanes &
parking places

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

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

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

81. Acid rain has many harmful effects

82. Effects of Acid rain:
 dissolves limestone

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

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

86. Question: SEP, 2008
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.

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

89. Question: MAY, 2011 (2B)
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.

90. To reduce pollutants in air, cars are fitted
with: 1. Filters – diesel engines

91. 2. catalytic converters – petrol engines
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

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

94. 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]

95.  Clean energy

96. Non-renewable energy
 Cause of air pollution

97. Solar energy
Wind energy

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

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

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

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

102. Algal bloom
Satellite image

103. Eutrophication

106. Dead fish in China [2010]

107. Question: MAY, 2009
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.

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

109. Saprophytic bacteria in sewage treatment plants
remove harmful nutrients from raw sewage
An aerial view of the Gozo
sewage treatment plant

110. Sant’ Antnin Sewage Treatment Plant
[Marsascala]

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

112. First settling tank

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

115. Malta: Water from sewage treatment
used for plant irrigation

116. What happens to the effluent?
EFFLUENT
sea
irrigation

117. Sewage at Mellieha [2009]

118. Question: MAY, 2012
Ta’ Barkat sewage treatment at Xghajra has
significantly reduced the amount of raw sewage
disposed at sea.
a) Air is pumped in one of the sewage tanks
where bacteria are metabolically active.
Explain the importance of this process. (2)
b) Give TWO reasons why it is important to
reduce raw sewage disposal at sea. (4)
c) Describe ONE way how the pumped water by-product
of sewage treatment may be used. (1)

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

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

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

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

123. Pesticides are chemicals that kill pests

124. 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

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

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

127. 3. Causes water pollution.

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

129. DDT & dieldrin are now banned from
most countries

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

131. 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

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

134. Ladybirds feed upon aphids
(greenflies)

135. Fish eat larvae
of mosquito

136. Biological control gone wrong:
Cane toads in Australia

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

138. 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

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

140. Oil spillages from tankers cause harm

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

142. Birds die: too heavy to fly

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

144. Beaches are spoilt

145. Seashore animals & plants become
covered with oil

146. What about
plastic at sea?

147. Plastic in the sea harms animals

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

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

151. 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

152. 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

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

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

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

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

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

158. Plastic lining at a landfill

159. Engineered landfill at Maghtab

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

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

163. 2. Visual pollution

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

165. Question: MAY, 2010
The Yelkouan Shearwaters
(il-Garnija) is a special bird
for Malta. Several of these
birds breed at Rdum tal-
Madonna in L- Aħrax tal-
Mellieħa.

166. Describe how each of the following threats lead
to a decrease in the population of Yelkouan
Shearwaters:
i) uncollected rubbish from the camping site
at L- Aħrax tal-Mellieħa; (3)
Rubbish leads to a proliferation of rats these
will kill the chicks therefore population in
number. Also prevent them from reaching
sexual maturity and breeding.

167. ii) loud music on lit boats during boat parties.
(2, 2)
Loud music prevents communication between
birds. The light and loud music interfere with
reproduction, thus fewer eggs are laid. This
results in a decrease in the population.

168. iii) Pushing old cars off the cliffs. (3)
The cars may close entrances to burrows where
the birds nest therefore they do not breed.

169. Question: MAY, 2009
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

171. Fish farming is the:
 rearing of aquatic
organisms under
controlled conditions
Started in 1980’s in Malta

172. Fish can be grown in tanks on land
Guatemala

173. in nets in the sea

174. Malta farms 84% of all the fish it
produces

175. Bluefin tuna are caught from the sea
and fattened in cages
Bluefin tuna
Towing a cage with
bluefin tuna

176. What are ‘fish stocks’?
Fish growing
naturally at
sea.

177. Eggs from females are fertilised & the
young fish are grown
Advantage:
Natural fish
stocks are
conserved

178. Reared fish are intended for:
1. food (have a high protein content)
Sea bream (awrat)
Sea bass (spnott)

179. Reared fish are intended for:
2. recreation (when
lakes are restocked
with fish for fishing as
a hobby)
Fish farmer releases
carp into the lake

180. What can be
grown on a
fish farm?
 Fish
 Lobsters
 Shrimps
 Oysters
 Mussels
 Algae
Oyster fish farm

181. Algae are grown for food

182. Seaweed may become an abundant
source of biofuels.

184. More fish can be grown on a fish farm than
in nature, in the same volume of water
But fish must be fed!!

185. Is all the food eaten by the fish?

186. A fish farm causes
damage to the
environment by:
1. Fish waste
2. uneaten food

187. Advantages of fish
farming:
1. Fish do not move much and so are more
efficient in converting food into biomass
2. Fewer lost to predation
3. Conservation of wild fish stocks
4. Easier to catch
5. Food quality can be controlled
6. Can be genetically engineered

188. Disadvantages of fish
farming:
1. Disease is more likely
2. More antibiotics are thus used
3. High cost of food
4. Expensive to set up
5. Pollution of environment by uneaten food
and fish wastes
6. Food chain is affected due to pollution

189. Question: MAY, 2012 (2A)
Comment on the biological significance of each of the
following statements.
Fish farming is a possible way of limiting the decrease
in fish stock, however it has a number of
disadvantages. (5)
Fish farming can help to limit the decrease in fish stock by farming
species of fish under captive conditions. (2 marks)
However fish farming has a number of disadvantages including:
spread of disease higher than normal, excessive use of antibiotics,
pollution from the fish waste, excessive use of pesticides to control
parasites affecting fish, farmed fish may escape and compete for
food with wild fish; may be fed on fish meal made from wild fish.
(3 marks)
(Award 1 mark each for each disadvantage mentioned.)

191. What is ‘conservation’?
To conserve something means to protect
it and keep it in a healthy state.

192. Ways to conserve the environment:
1. Setting up of
nature reserves
to protect
endangered
species

193. What are ‘endangered species’?
Endangered species are present in small
numbers that risk extinction.
e.g. of endangered species in Malta:
Great white shark Basking shark
A great white shark was caught in Malta by
Alfredo Cutajar in April 16, 1987. This shark was
also estimated to be around 7.13 m (24 ft).

194. Ways to conserve the environment:
2. Setting up laws to prevent
overhunting and overfishing.
Police stop illegal bird
trapping in Malta

195. Overhunting/overfishing is when more
individuals are caught than nature can replace
Bison skulls
(1890)

196. Overhunting/overfishing is when more
individuals are caught than nature can replace
Overfishing of cod.

197. What are ‘protected species’?
Species that cannot be caught, sold or killed
Examples:
 Dolphins
 Turtles
 Frogs
Narcissus
Loggerhead turtle [Narcis]

198. Maltese Rock Centaury
Widnet il-Bahar
Blue Rock
Thrush 'Merill'
Sandarac gum tree is-
Sigra tal-Gharghar

199. Ways to conserve the environment:
3. Helping rare animals to reproduce in zoos to
prevent their extinction.
Artificial insemination of a
panda in a zoo.

200. Ways to conserve the environment:
4. When fishing, nets
must have large
holes to let the
young escape.

201. Ways to conserve the environment:
5. Damaged rubble walls must be rebuilt to:
 prevent soil erosion
 conserve the wild life living in them

203. Il-Buskett is considered as an area of
ecological importance:
1. Many trees are present = many types of
birds

204. 2. There is a freshwater stream in which many
species live. Such streams are not common in
the Maltese Islands.
Wied il-luq

205. Question: SEP, 2009
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

206. 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.

207. What is the main problem related to the
conservation of agricultural land in the
Maltese Islands?
There is so little
of it, that it is
overused with
the possible risk
of soil erosion.

208. THE END