People and planet

1. Chapter 6
Biology
(part 2)

2. 
 Many people still live as people did in the past- they
use animals to provide power, and fuel wood for
cooking.
 In countries where industry has developed :
-People have electricity in their homes and workplaces.
-They travel with vehicles .
-Vehicles move with diesel and petrol engines.
-Fresh food is bought from near by countries by planes.
People today

3. 
Changes on land:
-When people began farming, they destroyed the
habitats , organisms and food chains ,that bound
organisms together, on this land to grow crops.
-Pesticides are chemicals which are now used to kill
pests which destroy crops, but they may be harmful to
other animals.
Changes in the environment

4. 
How pesticides harm other
animal?

5. 
 As factories and trade began to grow and large
amount of fuel for steam engines were needed, coal
mines were dug also cast mines were dug as they
needed large amounts of metals , destroying the
habitats and their food chains.
 Rocks containing metals, called :Ores.
Bad influence of factories on
land

6. 
Changes in the sea

7. 
 Five billion years ago nitrogen, carbon dioxide and
water vapour were the first atmospheric gases on
earth they were produced from erupting volcanoes.
 Three billion years ago plants started to produce
oxygen in the atmosphere too as a result of
photosynthesis process.
 Oxygen + ultra violet Ozone layer.
 Ozone layer is formed 25 Km above the earth’s
surface ,it makes the earth safer as it screens large
amount of harmful sunlight rays.
Changes in the atmosphere

8. 
 Sun rays pass through atmosphere to earth’s surface
were some warms the earth and some are radiated to
the space as it travels back through the atmosphere
some are absorbed by the carbon dioxide.

9. 
 Extra carbon dioxide produced by human activities
as burning fossil fuels in power stations and vehicles
exhausts will cause more heating effect and this may
produce great changes to habitats around the world.

10. 
 Sulfur containing gases may be produced from
erupting volcanoes and algae that live in the sea .
 Nitrogen containing gases may be produced by
lightning reacting with nitrogen in the atmosphere
or when fossil fuels are burnt at power stations and
factories.
 These gases dissolve in the water droplets in clouds
and make the rain slightly acidic which cause soil
damage, which kills plants.
Acid rain

11. 
 In 1920s, gases called: Chlorofluorocarbons (CFCs)
were made for the first time. They were used for
keeping things cool in the fridges and air conditioning,
and because they squashed easily they were used in
aerosol sprays. The CFCs entered the atmosphere. In
the 1980s, scientists noticed that holes were developing
in the ozone layer around the North Pole and South
Pole. When they investigated this, the scientists found
that CFCs destroy the ozone in the atmosphere and
since then the governments of 196 countries have
agreed to reduce the use of these chemicals.
The ozone layer