Cycles within Ecosystems

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 cycled through an ecosystem

Answer 3

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