1. How humans can affect the environment Spaced Learning
AQA Biology 3 Chapter 4
How humans can affect the environment
Spaced Learning

2. Population Explosion
Natural populations are kept in check by disease, lack of food, lack of habitat, predators or a build-up of waste.
Human beings have adapted to overcome these factors.
We have developed medicines to combat disease; fertilisers to grow enough food; and we have no natural predators.
As a consequence, the human population has been, and continues to grow.

3. Effect on Land Use
All the billions of people on Earth need somewhere to live.
In the UK we have changed the land use of many areas of the country.
Land to live on;
Land to have shops and industry on;
Land for roads.
A consequence of land use change is often a destruction of wildlife habitat.

4. Energy Resources
We use many non-renewable energy resources to help us to maintain our high standard of living.
Fossil fuels (such as oil, coal and gas) are used for:
generating electricity;
manufacturing plastics;
vehicle fuel for transportation.

5. Managing Waste
As a consequence of our ever increasing population we are generating an ever increasing amount of waste:
sewage;
unwanted/uneaten food;
packaging;
disposable goods;
industrial waste.
A large area of land is given over to the dumping of this waste.
If our waste is not handled properly, the local environment can become seriously polluted.

6. Land Pollution
In many developing countries, sewage is pumped into landfill. This causes chemicals and parasites to seep into the surrounding land making it very dangerous to human health and wildlife.
Chemical waste from industry can also leach into the ground causing serious problems to habitats and populations.

7. Farm chemicals
Herbicides (weed killer) and pesticides (pest killer) are sprayed onto crops to increase their yield by destroying competition or pests.
These chemicals are poisons which soak into the soil and then may be washed into nearby water systems.
These poisons can also become part of the food chain of many wildlife species and lead to a build-up of poisons in top predators.

8. Water Pollution
Fertilisers sprayed on crops can also wash into water systems.
The build up of fertilisers in streams and rivers can lead to the process of eutrophication.
Oxygen levels in the water drop so low that all aquatic animals die and the stream or river becomes ‘dead’.

9. Air Pollution A major source of air pollution is burning fossil fuels.
Carbon dioxide is produced when they burn.
Sulphur dioxide is produced when sulphur impurities are present.
Nitrogen oxide is produced at high temperatures (such as in a car engine).
Sulphur dioxide and nitrogen oxide dissolve in rainwater to form acid rain.

10. Effects of Acid Rain Acid rain can:
defoliate trees;
soak into soil and destroy root systems;
cause lakes, rivers and streams to become ‘dead’ by increasing the acidity of the water.
Often the country which produces the toxic gases are not the ones which feel the effects of acid rain. Wind systems carry the sulphur dioxide and nitrogen oxide in the air.

11. Combating Acid Rain
In the UK (and many other European countries) we have switched to burning gas (a low-sulphur fuel) in our power stations.
We also utilise nuclear power much more.
We also monitor and clean the emissions coming from our power stations before they enter the air systems.

12. Global Dimming
One form of air pollution is still a major concern – global dimming.
An increase in the number of tiny solid particles (such as the sulphur products from burning fossil fuels) and any type of smoke particle.
These particles reflect some of the sunlight coming to Earth and may lead to a global fall in the Earth’s surface temperature.

13. Deforestation
Deforestation occurs due to a need for wood and to clear land for farming.
‘Slash and burn’ clearance is where the trees are felled and burned in order to clear an area quickly.
The land is only fertile for a short period, so the process is repeated often.
No trees are planted to replace those cut down.
Therefore the area of forest is ever decreasing.

14. Effect of Deforestation
An increase of carbon dioxide released into the atmosphere:
burning trees releases CO2 from combustion;
dead vegetation decays – the microorganisms involved in the decay process release CO2 as they respire;
the missing trees can no longer act as a ‘carbon sink’.

15. Loss of Biodiversity
The rainforests are the habitat of many different species of plant, animals and insects.
Many of these species have not even been identified or studied.
By destroying the forest we are losing biodiversity.

16. Peat Bog Destruction Peat acts as a massive carbon store.
Peat is found in marshy areas where conditions are highly acidic and low in oxygen. This means that plant material cannot readily decay.
Peat can be burned as a fuel or used by gardeners to improved their soil.
When this happens the ‘carbon store’ is lost and carbon dioxide is released into the atmosphere.

17. Global Warming
Global warming is an increase in the warmth of the Earth’s climate.
For millions of years the amount of carbon dioxide released into the atmosphere (by things like respiration) was match by the amount removed during photosynthesis or dissolved in oceans, lakes and rivers.
Carbon dioxide is sequestered by water and plants. I.e. they act as carbon sinks.

18. Global Warming
At present, the human population of the Earth is increasing and as a result of our activities:
levels of carbon dioxide produced are increasing; and
numbers of plants available to absorb it are decreasing.
Natural sinks cannot cope so global levels of CO2 and methane in the atmosphere are increasing.

19. The Greenhouse Effect
Energy from the Sun reaches the Earth and much of it is bounced back.
However, substance such as carbon dioxide and methane absorb the energy so that it cannot escape.
Carbon dioxide and methane are known as greenhouse gases.
The way they keep the surface of the Earth warm is known as the greenhouse effect.

20. Global Warming An increase in global temperatures may cause:
Big changes in the Earth’s climate;
A rise in sea levels;
Reduced biodiversity;
Changes in migration patterns;
Changes in distribution.

21. Biofuels
Biofuels are made from natural products by fermentation using yeast or bacteria.
Biofuels are split into ethanol-based products and biogas.
Ethanol-based fuels are produced from fast growing crops such as sugar cane or maize.
The sugar rich parts of these crops are fermented anaerobically with yeast. The products are ethanol and carbon dioxide. Distillation is used to extract the ethanol.

22. Advantages and Disadvantages
Producing ethanol is carbon neutral process.
Burning ethanol does not produce any unwanted gases such as nitrogen oxides or sulphur dioxide.
Ethanol can be mixed with petrol to produce gasohol.
The main disadvantage is the amount of space required to grow the vast quantities of crops.
Often this space is taken from other habitats such as rainforest.

23. Biogas
Biogas is a flammable mixture of gases (usually mainly methane).
It is produced when bacteria breakdown plant or animal waste in anaerobic conditions.
The plant material and animal waste (including human waste) contain carbohydrates. Which are a large energy source.

24. Biogas Generators
The bacteria in biogas generators tend work best at a constant 300C. Therefore biogas generators work well in hot countries.
However, the reaction inside is exothermic. So as long as you insulate your generator well and provide the initial energy to get things started, a biogas generator could work anywhere.

25. Efficient Food Production
There is a limited amount of space on Earth to grow food.
The most efficient use of this space would be to grow crops and eat the crops directly (i.e. don’t feed them to animals and then eat the animals).
Every extra stage we add to the process results in less energy getting to us.

26. Farmers Increasing Yield
To maximise the amount of biomass a farmer gets from things like eggs, meat and milk they control:
The amount of movement animals have; and
The temperature of their surroundings.
This can result in scenarios such as massive poultry rearing sheds – where animals have little room to move around and are kept nice and warm.

27. Sustainable Food Production
Sustainable food production means producing food in such a way that it can continue for many years.
This includes maintaining the health of the soil in which we grow crops and maintaining fish stocks.

28. Managing the Oceans
Over the past 60 years huge fishing vessels have been developed which can take vast quantities of fish at one time.
Many breeding age fish have been taken and as a result fish populations of edible fish have declined drastically – many to unsustainable levels.
Ways to overcome this are:
Size of holes in nets which catch only the big fish; and
Limiting the fishing season to avoid the breeding season.

29. Mycoprotein Mycoprotein in a food based on the protein from fungi.
The fungus grows and reproduces rapidly feeding on a cheap sugar syrup inside a large container called a fermenter.
The fungus need aerobic conditions so the fermenters need to have a good air supply.

30. Population Explosion
Natural populations are kept in check by ______, ____ _ ____, ____ __ ______, _________ or a build-up of _____.
Human beings have adapted to overcome these factors.
We have developed ________ to combat disease; ________ to grow enough food; and we have no ______ ________.
As a consequence, the human population has been, and continues to grow.
disease
lack of food
lack of habitat
predators
waste
medicines
fertilisers
natural predators

31. Effect on Land Use
All the billions of people on Earth need somewhere to live.
In the UK we have changed the land use of many areas of the country.
Land to ___ __;
Land to have _____ ___ _______on;
Land for _____.
A consequence of land use change is often a destruction of ______ ______.
live on
shops and industry
roads
wildlife habitat

32. Energy Resources
We use many ___ _________ energy resources to help us to maintain our high standard of living.
Fossil fuels (such as __, ____ and ___) are used for:
generating _________;
manufacturing _______;
______ ____for transportation.
non-renewable
oil
coal
gas
electricity
plastics
vehicle fuel

33. Managing Waste
As a consequence of our ever increasing population we are generating an ever increasing amount of ______:
_______;
_________ _______ ____;
_________;
_________ _____;
________ _____.
A large area of land is given over to the ________of this waste.
If our waste is not handled properly, the local environment can become _______ ________.
waste
sewage
unwanted/uneaten food
packaging
disposable goods
industrial waste
dumping
seriously polluted

34. Land Pollution
In many developing countries, ______is pumped into ______. This causes ________ and ________to seep into the surrounding land making it very dangerous to human health and wildlife.
Chemical waste from _______can also leach into the ground causing serious problems to _______and __________.
sewage
landfill
chemicals
parasites
industry
habitats
populations

35. Farm chemicals
_________(weed killer) and ________(pest killer) are sprayed onto crops to increase their ____by destroying __________ or _____.
These chemicals are ______which soak into the soil and then may be washed into nearby water systems.
These poisons can also become part of the ____ _____of many wildlife species and lead to a build-up of poisons in top ________.
Herbicides
pesticides
yield
competition
pests
poisons
food chain
predators

36. Water Pollution Fertilisers
________sprayed on crops can also wash into water systems.
The build up of fertilisers in streams and rivers can lead to the process of ____________.
Oxygen levels in the water drop so low that all aquatic animals die and the stream or river becomes ‘_____’.
Fertilisers
eutrophication
dead

37. Air Pollution A major source of air pollution is burning ____ _____.
______ ______ is produced when they burn.
______ _______is produced when sulphur impurities are present.
_______ _____is produced at high temperatures (such as in a car engine).
Sulphur dioxide and nitrogen oxide dissolve in rainwater to form ____ ___.
fossil
fuels
Carbon dioxide
Sulphur dioxide
Nitrogen oxide
acid rain

38. Effects of Acid Rain Acid rain can:
________trees;
soak into soil and ______ ____ ______;
cause lakes, rivers and streams to become ‘_____’ by increasing the ______of the water.
Often the country which produces the toxic gases are not the ones which feel the effects of acid rain. _____systems carry the sulphur dioxide and nitrogen oxide in the ___.
defoliate
destroy root systems
dead
acidity
Wind
air

39. Combating Acid Rain
In the UK (and many or European countries) we have switched to burning ___(a ____ ______ fuel) in our power stations.
We also utilise ______power much more.
We also _______and _____the emissions coming from our power stations before they enter the air systems.
gas
low-
sulphur
nuclear
monitor
clean

40. Global Dimming
One form of air pollution is still a major concern – _____ _______.
An increase in the number of ___ ____ _______(such as the sulphur products from _______ ____ ____) and any type of ______ particle.
These particles ______some of the _______ coming to Earth and may lead to a global ____ in the Earth’s surface temperature.
global dimming
tiny solid
particles
burning fossil fuels
smoke
reflect
sunlight
fall

41. Deforestation
___________ occurs due to a need for _____ and to clear land for ______.
‘____ ___ ____’ clearance is where the trees are felled and burned in order to clear an area quickly.
The land is only ______for a short period, so the process is repeated often.
No _____are planted to replace those cut down.
Therefore the area of forest is ever _________.
Deforestation
wood
farming
Slash and burn
fertile
trees
decreasing

42. Effect of Deforestation
An increase of carbon dioxide released into the atmosphere:
_______trees releases CO2 from __________;
dead vegetation ______– the microorganisms involved in the decay process release CO2 as they ______;
the missing trees can no longer act as a ‘______ ____’.
burning
combustion
decays
respire
carbon
sink

43. Loss of Biodiversity
The rainforests are the habitat of many _______ ______of plant, animals and insects.
Many of these species have not even been ________or ______.
By destroying the forest we are losing __________.
different species
identified
studied
biodiversity

44. Peat Bog Destruction carbon store Peat acts as a massive ______ ____.
Peat is found in marshy areas where conditions are highly ____ and low in ______. This means that plant material cannot readily ______.
Peat can be ______ as a fuel or used by ________ to improved their soil.
When this happens the ‘______ ____’ is lost and ______ ______is released into the atmosphere.
carbon store
oxygen
acidic
decay
burned
gardeners
carbon store
carbon dioxide

45. Global Warming
Global warming is an increase in the ______ of the Earth’s ______.
For millions of years the amount of carbon dioxide _______into the atmosphere (by things like respiration) was ______by the amount removed during _____________or ________in oceans, lakes and rivers.
Carbon dioxide is __________by water and plants. I.e. they act as ______ ____.
warmth
climate
released
match
photosynthesis
dissolved
sequestered
carbon sinks

46. Global Warming
At present, the human population of the Earth is ________ and as a result of our activities:
levels of carbon dioxide produced are _________; and
numbers of plants available to absorb it are _________.
Natural sinks cannot cope so global levels of ____ and ________in the atmosphere are increasing.
increasing
increasing
decreasing
CO2
methane

47. The Greenhouse Effect
Energy from the Sun reaches the Earth and much of it is ________ back.
However, substance such as ______ ______ and ________absorb the energy so that it cannot escape.
Carbon dioxide and methane are known as __________ ____.
The way they keep the surface of the Earth warm is known as the __________ _____.
bounced
carbon dioxide
methane
greenhouse gases
greenhouse effect

48. Global Warming An increase in global temperatures may cause:
Big changes in the Earth’s _______;
A rise in ___ _____;
Reduced ___________;
Changes in ________ _______;
Changes in __________.
climate
sea levels
biodiversity
migration patterns
distribution

49. Biofuels
Biofuels are made from natural products by ___________using _____or _______.
Biofuels are split into ____________ products and ______.
Ethanol-based fuels are produced from fast growing crops such as sugar cane or maize.
The sugar rich parts of these crops are fermented ____________with yeast. The products are ethanol and carbon dioxide. _________is used to extract the ethanol.
fermentation
yeast
bacteria
ethanol-based
biogas
anaerobically
Distillation

50. Advantages and Disadvantages
Producing ethanol is ______ ______process.
Burning ethanol does not produce any unwanted gases such as ______ ______or ______ ______.
Ethanol can be mixed with petrol to produce _______.
The main disadvantage is the amount of ______ required to grow the vast quantities of crops.
Often this space is taken from other habitats such as _________.
carbon neutral
nitrogen oxides
sulphur dioxide
gasohol
space
rainforest

51. Biogas
Biogas is a _________ mixture of gases (usually mainly ________).
It is produced when _______breakdown plant or animal waste in ________conditions.
The plant material and animal waste (including human waste) contain ____________. Which are a large energy source.
flammable
methane
bacteria
anaerobic
carbohydrates

52. Biogas Generators
The bacteria in biogas generators tend work best at a constant ____. Therefore biogas generators work well in hot countries.
However, the reaction inside is _________. So as long as you _______ your generator well and provide the initial energy to get things started, a biogas generator could work _________.
300C
exothermic
insulate
anywhere

53. Efficient Food Production
There is a limited amount of _____on Earth to grow food.
The most efficient use of this space would be to ____ _____and ___ ___ ____directly (i.e. don’t feed them to animals and then eat the animals).
Every extra stage we add to the process results in less ______ getting to us.
space
grow crops
eat the crops
energy

54. Farmers Increasing Yield
To maximise the amount of _______ a farmer gets from things like eggs, meat and milk they control:
The amount of _________ animals have; and
The __________ of their surroundings.
This can result in scenarios such as massive ______ ______ _____– where animals have little room to move around and are kept nice and warm.
biomass
movement
temperature
poultry rearing sheds

55. Sustainable Food Production
Sustainable food production means producing food in such a way that it can _______ for many _____.
This includes __________the health of the___ in which we grow crops and maintaining ____ ______.
continue
years
maintaining
soil
fish
stocks

56. Managing the Oceans
Over the past 60 years huge fishing vessels have been developed which can take vast quantities of fish at one time.
Many ________age fish have been taken and as a result fish populations of ______fish have declined drastically – many to ___________ levels.
Ways to overcome this are:
Size of _____in nets which catch only the big fish; and
Limiting the fishing season to avoid the ________ season.
breeding
edible
unsustainable
holes
breeding

57. Mycoprotein Mycoprotein is a food based on the ______ from _____.
The fungus grows and reproduces ______ feeding on a cheap sugar syrup inside a large container called a _________.
The fungus need _______conditions so the fermenters need to have a good ___ _____.
protein
fungi
rapidly
fermenter
aerobic
air supply