B13 Human influences on ecosystem

Question 1

describe the carbon cycle (6)

Answer 1

• photosynthesis
• respiration
• feeding
• decomposition
• fossilisation
• combustion

Question 2

describe the effects of combustion of fossil fuels

Answer 2

co2 increases o2 decreases

Question 3

list the effects of deforestation (4)

Answer 3

• loss of habitat
• loss of soil
• flooding
• increase of co2 in the atmosphere

Question 4

list the sources of water pollution (4)

Answer 4

• chemical waste
• discarded rubbish
• untreated sewage
• fertiliser

Question 5

describe the process of eutrophication (6)

Answer 5

• fertilizers provide nitrate and other ions when they leak into the water
• it causes the rapid growth of algae on the river surface
• after it dies, increased decomposition
• it increases aerobic respiration
• it reduces oxygen present in the lake
• death of organisms requiring the oxygen in the water