Ecology: Human influences on the environment

Question 1

Sulfur Dioxide
Source:
Effect:

Answer 1

Combustion of fossil fuels that contain sulphur impurities
Fossil fuel combustion
Reacts with oxygen and dissolves in rainwater to produce sulphuric acid, leading to acid rain
Acid rain can damage parts of trees and plants
It can make rives and lakes too acidic, resulting in the death of aquatic organisms
Can also cause leaching of toxic minerals into lakes

Question 2

5 Greenhouse gases

Answer 2

Water vapour
Carbon dioxide
Nitrous oxides
Methane
CFCs

Question 3

Human activities contributing to greenhouse gases

Answer 3

Combustion of fossil fuel - CO2 produced
Methane is produced by cattle

Question 4

Greenhouse effect

Answer 4

The sun emits rays that enter the Earth’s atmosphere
The heat bounces back from the Earth’s surface
Some heat is reflected back out into space
Some heat is absorbed by greenhouse gases and trapped within the Earth’s atmosphere
However, as the levels of greenhouse gases in the atmosphere rise, Earth’s average temp rises beyond normal, causing global warming

Question 5

Consequences of global warming

Answer 5

Rising sea levels
Extreme weather
Change/loss of habitats
Decrease in biodiversity
Increase of migration of species to new places

Question 6

Untreated sewage consequences

Answer 6

Sewage provides a good source of bacteria which increase rapidly
This depletes oxygen dissolved in the water as they respire aerobically
The lack of oxygen causes the death of aquatic organisms -
This is called Eutrophication

Question 7

Eutrophication caused by leached minerals from fertiliser

Answer 7

Fertilisers containing nitrates washed off land by rain, into freshwater ponds or rivers
Algae form algal bloom as nitrate levels rise, and reproduce rapidly
Algae prevent light reaching the plants at the bottom of the pond
Plants cannot photosynthesize and die - decrease in oxygen levels
Algae also die as they run out of nitrates
Bacteria decompose large quantities of dead plants and algae
Bacteria reproduce, increase in number increases aerobic respiration, using up oxygen
Bacteria use up all oxygen in water - water becomes anoxic. Other pond life die

Question 8

Consequences of Deforestation

Answer 8

Extinction/loss of biodiversity
Leaching (minerals not taken up, washed away into bodies of water)
Soil erosion (tree roots gone)
Flooding (reduced water absorption)
Disturbance of the water cycle (reduces water vapour released via transpiration, less cloud formation and rainfall)

Question 9

Soil Erosion

Answer 9

Tree roots help stabilise the soil, preventing it from being eroded by rain
Trees will usually take up nutrients and minerals from the soil through their roots
Without trees, nutrients and minerals will remain unused in the soil, so it will be washed away into rivers and lakes by rain (leaching)