Cycles within Ecosystems and Human Influences on the Environment

Question 1

Give 3 molecules which are cycled through ecosystems

Answer 1

Oxygen, carbon dioxide and water

Question 2

Briefly describe how carbon dioxide is cycled through an ecosystem

Answer 2

• Carbon dioxide is fixed through photosynthesis
• Respiration releases carbon dioxide
• Decomposition releases carbon dioxide
• Combustion releases carbon dioxide

Question 3

Briefly describe how nitrogen is cycle through an ecosystem

Answer 3

• Nitrogen is fixed by lighting, the Haber process and bacteria
• Decomposers break down dead matter into ammonia
• Nitrifying bacteria convert ammonia into nitrites and nitrates
• Denitrifying bacteria release nitrogen back to the atmosphere

Question 4

What detrimental impacts can sulphur dioxide have on the environment?

Answer 4

• Formed when fossil fuels containing impurities are burnt
• Sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources

Question 5

What detrimental impacts can carbon monoxide have on the environment?

Answer 5

• Carbon monoxide is formed from the incomplete combustion of fossil fuels
• Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
• Too much exposure can lead to unconsciousness and death

Question 6

Name 5 greenhouse gasses

Answer 6

• Water vapour
• Carbon dioxide
• Nitrous oxide
• Methane
• CFCs

Question 7

Give 3 human activities that contribute to greenhouse gases

Answer 7

• Burning fossil fuels
• Deforestation
• Large scale livestock farming

Question 8

How do greenhouse gases lead to global warming?

Answer 8

• Greenhouse gases allow heat from the sun to enter the atmosphere
• The gases act as a ‘blanket’ and trap the heat in the atmosphere

Question 9

State 3 negative consequences of global warming

Answer 9

• Sea level rise caused by melting icebergs
• Disrupted farming and agriculture
• Increased spread of diseases in warmer climates

Question 10

Describe how sewage in waterways can affect aquatic life

Answer 10

Microorganisms that decompose sewage will use up the oxygen in the water so that there is not enough oxygen left for respiration for other aquatic organisms

Question 11

What is eutrophication?

Answer 11

An excess of nutrients in a body of water, often due to fertilisers in the water source

Question 12

Why is eutrophication bad for aquatic life?

Answer 12

It causes an ‘algal bloom’ which decreases supplies in the water and degrades the water quality

Question 13

State 5 negative effects of deforestation

Answer 13

• Leaching
• Less COs taken out of the atmosphere from photosynthesis
• Soil erosion
• Habitat disruption
• Disruption of the carbon cycle

Question 14

What is leaching?

Answer 14

• Trees usually take up a lot of nutrients.
• When lots of trees are cut down, these nutrients can leak out into waterways.
• Large quantities of nutrients in waterways can cause problems like agal blooms

Question 15

What is evapotranspiration?

Answer 15

Evapotranspiration is the process involving trees proving lots of water to the atmosphere from the soil through evaporation and transpiration

Question 16

What effect does deforestation have on evapotranspiration?

Answer 16

• Less trees means that there will be less evapotranspiration
• This means that less water will be returned to the atmosphere as quickly
• This causes areas to dry up