4.7.2.2 How materials are cycled

Question 1

How are different materials cycled?

Answer 1

many different materials cycle through the abiotic and biotic components of an ecosystem

Question 2

What is vital for life on Earth?

Answer 2

• the carbon and water cycles
• important for living organisms

Question 3

What happens to all materials in the living world?

Answer 3

all materials in the living world are recycled to provide the building blocks for future organisms

Question 4

What takes place in the carbon cycle?

Answer 4

• CO2 is removed from the air in photosynthesis by green plants and algae - they use the carbon to make carbohydrates, proteins and fats - they are eaten and the carbon moves up the food chain
• then the carbon cycle returns CO2 from organisms to the atmosphere when plants, algae and animals respire which can they be used by plants again in photosynthesis
  
  • decomposers (a group of organisms that break down dead organisms waste) respire while they return mineral ions to the soil
• CO2 is also returned to the atmosphere when wood and fossil fuels are burnt (combustion) as they contain carbon from photosynthesis

Question 5

What takes place in the water cycle?

Answer 5

• the sun’s energy causes water to evaporate from the sea and lakes - forming water vapour
• water vapour is also formed as a result of transpiration in plants
• water vapour rises and then condenses to form clouds
• water is returned to the land by precipitation and this runs into lakes to provide water for plants and animals - this runs into seas and the cycle begins again
• the water cycle provides fresh water for plants and animals on land before draining into the seas
• water is continually evaporated and precipitated

Question 6

What is the role of microorganisms?

Answer 6

return carbon to the atmosphere as carbon dioxide and mineral ions to the soil