Ecology and the Environment - Human Influences on the Environment

Question 1

what are the consequences of pollution by sulfur dioxide?

Answer 1

• acid rain leaches minerals and nutrients out of the soil, causing plant and tree death
• acid rain damages the waxy layer of leaves
• acid rain acidifies rivers and lakes
• acid rain corrodes metal and limestone in buildings

Question 2

what are the consequences of pollution by carbon monoxide?

Answer 2

• poor oxygen transport
• may cause emphysema
• hindering fetal growth as there’s insufficient oxygen for respiration

Question 3

what are examples of greenhouse gases?

Answer 3

water vapour, carbon dioxide, nitrous oxide, methane and CFCs

Question 4

how do human activities contribute to rising levels of greenhouse gases?

Answer 4

• carbon dioxide is produced during combustion of fossil fuels
• nitrous oxide is produced from fertilisers and cattle in farms
• methane is released from rice paddy fields and cattle
• CFCs are used in aerosol sprays and fridges

Question 5

how does an increase in greenhouse gases result in an enhanced greenhouse effect?

Answer 5

• sun emits short wave radiation which is absorbed and re-emitted at a longer wavelength by the Earth’s surface
• greenhouse gases in the atmosphere absorb and re-radiate the longer wave radiation
• so heat is retained within the atmosphere to increase global temperatures

Question 6

what are the biological consequences of the pollution of water by sewage?

Answer 6

• sewage is rich in minerals and nutrients which provide large amounts of energy for organisms such as decomposers to reproduce
• sewage also causes algal bloom, which blocks sunlight
• lack of sunlight prevents plants from absorbing sunlight via photosynthesis
• decomposers will break down sewage and dead plants via respiration, depleting oxygen in the water

Question 7

what are the biological consequences of eutrophication?

Answer 7

• excessive nutrients from fertilisers in farms are washed into rivers and lakes by rain
• this causes rapid plant growth and an algal bloom
• the algal bloom blocks sunlight, which prevents plants from absorbing sunlight via photosynthesis, resulting in the death of aquatic plants
• oxygen levels in rivers and lakes deplete
• decomposers will break down dead plants via aerobic respiration, depleting oxygen reserves in water