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)
34.
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
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.
48.
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
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
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
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.
83. Effects of Acid rain:
reduces the growth of
plants and damages leaves
84.
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
88.
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.
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
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]
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
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
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)
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
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
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
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
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
170.
171. Fish farming is the:
rearing of aquatic
organisms under
controlled conditions
Started in 1980’s in Malta
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.)
190.
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
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
202.
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.