Carbon Cycling (4.3)

Question 1

Carbon is released into the atmosphere by:

Answer 1

• Respiration (in particular by decomposers)
• Methane production
• Combustion of fossil fuels and biomass
• Limestone decomposition
• Diffusion

Question 2

Carbon Release: Respiration

Answer 2

Carbon dioxide is produced through respiration and diffuses out of organisms into water or the atmosphere. In particular respiration by decomposers eg. saprophytic bacteria and fungi.

Question 3

Carbon Release: Methane

Answer 3

Methane CH₄ is produced under anaerobic conditions by methanogenic archaeans. Some diffuses into the atmosphere and accumulates in the ground. Methane is also produced in the gut of grass feeding animals eg. livestock and oxidizes to carbon dioxide and water in the atmosphere.

Question 4

Carbon Release: Combustion

Answer 4

The combustion of fossil fuels produces carbon dioxide and water. The combustion of biomass i.e. the burning of trees, produces carbon dioxide, methane and other harmful greenhouse gases.

Question 5

Carbon Release: Limestone Decomposition

Answer 5

Limestone (CaCO₃) decomposition caused by acidic environments or heat.

Question 6

Carbon is removed from the atmosphere by:

Answer 6

• Autotrophs (photosynthesis)

- Diffusion

Question 7

Carbon Removal: Autotrophs

Answer 7

Autotrophs (eg. plants and phytoplankton) convert carbon dioxide into carbohydrates and other carbon compounds through photosynthesis.

Question 8

Carbon Removal: Diffusion

Answer 8

Carbon dioxide diffuses from the atmosphere and/or ocean (bodies of water) to autotrophs.

Question 9

Carbon is stored as/in:

Answer 9

• Fossil Fuels
• Limestone
• Biomass
• In Aquatic Ecosystems
• Peat

Question 10

Carbon Storage: Fossil Fuels

Answer 10

Carbon is stored in fossil fuels. Fossil fuels are partially decomposed organic matter (mainly plants) from past geological eras that has converted into coal and oil/gas accumulating in porous rock. This process is called carbonification

Question 11

Carbon Storage: Limestone

Answer 11

Organisms like coral and Mollusca have bones or shells made of calcium carbonate so can become fossilised in limestone.

Question 12

Carbon Storage: Biomass

Answer 12

Biomass of living things (eg. plants, animals and plankton) have organic compounds containing carbon such as carbohydrates, proteins, fats, calcium carbonate bones and shells and chitin exoskeletons.

Question 13

Carbon Storage: Aquatic Ecosystems

Answer 13

In aquatic ecosystems (eg. oceans and lakes) carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.

Question 14

Carbon Storage: Peat

Answer 14

Peat is formed under wet, acidic and anaerobic conditions from organic matter that has not been fully decomposed by saprotrophs. Peat usually forms as thick deposits in boggy swamps.