People and planet

Chapter 6 Biology(part 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

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

How pesticides harm

other animal?

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

Changes in the sea

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

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.

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.

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

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