B13. Human influences on ecosystems

 (0654) Coordinated Sciences 2023/2024

Subheadings and Key concepts

• the Carbon cycle
• deforestation:
• extinction of species/ loss of biodiversity
• soil erosion
• flooding
• increase in atmospheric CO2
• water pollution
• eutrophication

B12. Organisms and their Environment

 (0654) Coordinated Sciences 2023/2024

Subheadings and Key concepts

• food chain, food web
• producer, consumer
• herbivore, carnivore, decomposer
• ecosystem, trophic level
• energy transfer between trophic levels

# 155 Summary of Human and Ecosystem

CO₂ and methane are greenhouse gases, trapping outgoing long wavelength radiation in the atmosphere and warming the Earth. Increased concentrations of these gases are causing global warming.

#154 Conservation of species, recycling sewage and paper

Koala is an endangered animal.

Conservation is the process of looking after the natural environment. Conservation attempts to maintain or increase the range of different species living in an area, known as biodiversity.

#153 Pesticides, herbicides, nuclear fallout and non-biodegradable plastics

DDT spraying. 

Some pesticides are non-biodegradable and stay in the environment for a long time. For example, DDT has been a very effective insecticide, used to kill mosquitoes to reduce the spread of malaria. However, because it does not break down, it enters water systems such as lakes, where it is absorbed into plankton. 

#152 Greenhouse gases and global warming

Some gases in the Earth’s atmosphere stop heat radiating into space from the Earth. This is called the greenhouse effect and the gases involved are called greenhouse gases. They include:methane, CO₂ and water vapour. An increased greenhouse effect can lead to global warming and climate change.

15 Human and Ecosystem pdf

#151 Air pollution by sulfur dioxide (SO2), acid rain

SO₂ released into the air when coal and oil are burned. Power stations burn large amounts of these fossil fuels. SO₂ dissolves in the water vapour in clouds, forming sulphuric acid (H₂SO₄₎. When it rains, the rain is acidic.

#150 Overuse of fertilisers, water pollution by sewage

It is very tempting for farmers to increase the amount of fertilisers applied to crops to try and increase crop yields. However, this can lead to the eutrophication of rivers and lakes and the sequence occurs.  

# 149 Undesirable effects of deforestation

Deforestation is the removal of large areas of forest to provide land for farming and roads, and to provide timber (wood) for building, furniture and fuel. Deforestation has a number of undesirable effects on the environment.

#148 The human influences on the ecosystem

The use of modern technology resulted in increased food production.