9. Environment, Evolution & Energy Transfer Flashcards
Why is the human population rising so quickly?
Mostly due to modern medicine and farming
Why are humans having a greater impact on the Earth than we used to?
1) Increasing population -> Pressure on resources
2) Higher standard of living -> More luxuries -> More raw materials and energy needed
What effect is human waste having on water?
- Sewage and toxic chemicals from industry pollute lakes, rivers and oceans -> Affects plants and animals
- Chemicals used on land can be washed into water -> Eutrophication
What effect is human waste having on land?
- Toxic chemicals used for farming -> Wash into water
- Burying nuclear waste
- Dumping household waste in landfill sites
What effect is human waste having on air?
• Smoke and gases released -> Acid rain
In what ways do humans reduce the amount of land and resources available to plants and animals?
1) Building
2) Farming
3) Dumping waste
4) Quarrying for metal ores
What chemicals are used as mineral fertilisers which can cause eutrophication?
Nitrates and phosphates
When does eutrophication happen?
When fertilisers or sewage is leached into rivers and lakes.
Describe eutrophication.
1) Mineral ions from fertiliser or sewage enter water.
2) Increased concentration of these ions -> Faster growth of algae/plants
3) Water becomes full of plants -> Block light from reaching those lower down -> These can’t photosynthesise -> They die
4) More dead material as food for microorganisms -> Numbers of microorganisms increases
5) Respiration of these depletes oxygen in the water
6) Aerobic organisms die (e.g. fish) die due to reduced oxygen concentration
What two things can cause eutrophication?
- Sewage
* Fertiliser
Why can sewage cause eutrophication?
- It contains lots of phosphates from detergents
* It contains lots of nitrates from urine/faeces
What is deforestation?
The cutting down of forests.
Give two reasons why deforestation happens.
1) To provide timber -> Building material / Fuel
2) To clear land for farming -> Food / Fuel farming
What problems does deforestation in tropical areas lead to?
1) More methane in the atmosphere
2) More CO2 in the atmosphere
3) Less CO2 taken in
4) Less biodiversity
How does deforestation in tropical areas lead to more methane in the atmosphere?
1) Rice is grown in warm, waterlogged conditions -> Ideal for decomposers -> These produce methane
2) Cattle produce methane
How does deforestation in tropical areas lead to more CO2 in the atmosphere?
1) Burning trees releases CO2
2) Microorganisms feeding on dead wood release CO2 in respiration
How does deforestation in tropical areas lead to less CO2 being taken in?
Cutting down trees means less CO2 is removed from the atmosphere in photosynthesis.
How does deforestation in tropical areas lead to less biodiversity?
Cutting down trees destroys habitats for many species, which may become extinct.
What is biodiversity?
The variety of species in a habitat.
What are the problems of reduced biodiversity?
There are many products produced by species which are becoming extinct.
For example, newly discovered plants and animals are great source of food, fibres and medicines.
What are bogs?
Areas of land that are acidic and waterlogged.
What happens to plants that die in a peat bog?
They cannot decompose fully because there is a lack of oxygen. Instead of releasing the carbon inside into the atmosphere, the partly-rotted plants build up to form peat.
What is peat?
A brown substance formed when partly-rotted plants build up on acidic, boggy land.
What are the reasons for destroying peat bogs?
- To use the land as farmland
- The peat can be cut up, dried and used as a fuel
- The peat is also a good compost
What happens when a peat bog is destroyed?
The peat begins to decompose, releasing the carbon stored in the plants as CO2.
How can people stop the destruction of peat bogs?
They can buy peat free compost to reduce the demand for peat.
What is sequestered carbon dioxide?
Carbon dioxide which has been ‘locked up’ in natural stores.
How can carbon dioxide be sequestered?
- Oceans, lakes and ponds
- Green plants -> Stored as carbon compounds
- Peat bogs
How is CO2 removed from the atmosphere by plants?
By photosynthesis.
How does the atmosphere keep the Earth at a warm temperature?
The gases in it act as an insulating layer. They absorb the heat being radiated out by the sun and re-radiate it back to Earth.
What are greenhouse gases?
Gases that prevent heat being radiated off the Earth and out into space.
What are the two main greenhouse gases?
- Carbon dioxide
* Methane
What is global warming?
The process by which the Earth is heating up due to an increases in the amount of greenhouse gases in the atmosphere.
What are some effects of global warming?
1) Sea levels rising -> Flooding of low-lying places
2) Ice caps melting -> Even higher sea levels
3) Changes to weather -> More extreme weather - drought, hurricanes, etc.
4) Changes to distribution of animal and plant species
5) Reduced biodiversity
6) Changes to migration patterns
How could global warming affect distribution of animal and plant species?
- Wider distribution of species that prefer warm conditions
* Smaller distribution of species that prefer cold conditions
Name some ways in which scientists are monitoring climate change.
- Satellites -> Monitor snow and ice cover + Temperature of sea surface
- Recording temperature and speed of ocean currents
- Automatic weather stations -> Atmospheric temperatures
What things must be ensured in order for conclusions to be made about climate change happening?
The area monitored must be:
• Large
• Monitored over a long time period
Why is evidence for climate change considered generally reliable?
Several scientists get the same result using different methods.
What is theory of evolution?
More than 3 billion years ago, life on Earth began as simple organisms from which all the more complex organisms evolved.
How can organisms be classified?
By looking at their similarities and differences, then putting them into groups.