4.3 Carbon cycling

Question 1

What process do autotrophs use to convert carbon dioxide into carbohydrates and other carbon compounds?

Answer 1

Autotrophs use the process of photosynthesis to convert carbon dioxide (CO2) into glucose and other complex carbon compounds, utilizing sunlight as an energy source.

Question 2

How is carbon present in aquatic ecosystems?

Answer 2

In aquatic ecosystems, carbon is present as dissolved carbon dioxide (CO2) and hydrogen carbonate ions (HCO3-).

Question 3

How does carbon dioxide diffuse into autotrophs?

Answer 3

Carbon dioxide diffuses from the atmosphere or water into autotrophs, where it is used in the Calvin cycle to make carbohydrates and other complex carbon compounds.

Question 4

How is carbon dioxide produced and expelled by organisms?

Answer 4

Carbon dioxide is produced by cellular respiration as a waste product of metabolism and diffuses out of organisms into water or the atmosphere.

Question 5

How is methane produced and oxidised in the environment?

Answer 5

Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans. It can diffuse into the atmosphere or accumulate in the ground, and is oxidised to carbon dioxide and water in the atmosphere.

Question 6

How does peat form?

Answer 6

Peat forms when organic matter is not fully decomposed due to acidic and/or anaerobic conditions in waterlogged soils.

Question 7

How were coal, oil, and gas formed from organic matter?

Answer 7

Partially decomposed organic matter from past geological eras was converted into coal, or into oil and gas that accumulate in porous rocks, through pressure, heat, and time.

Question 8

What happens during the combustion of biomass and fossilised organic matter?

Answer 8

Carbon dioxide is produced by the combustion of biomass and fossilised organic matter, releasing carbon back into the atmosphere.

Question 9

How do animals like corals and molluscs contribute to the carbon cycle?

Answer 9

Animals such as reef-building corals and molluscs have hard parts composed of calcium carbonate which can become fossilised in limestone, contributing to the geological carbon cycle.

Question 10

What are the key components and processes in the carbon cycle?

Answer 10

Key components include autotrophs, heterotrophs, atmosphere, fossil fuels, and oceans. Processes involve photosynthesis, respiration, combustion, and sedimentation.

Question 11

How are carbon fluxes in the carbon cycle estimated?

Answer 11

Carbon fluxes, representing the movement of carbon between earth’s spheres, are estimated in gigatonnes using data from carbon sinks and sources.

Question 12

How do air monitoring stations contribute to our understanding of the carbon cycle?

Answer 12

Air monitoring stations, like Mauna Loa, measure atmospheric CO2 levels, providing data to analyze annual fluctuations and trends related to seasonal changes and human activities.

Question 13

What process is used by autotrophs to convert carbon dioxide into carbohydrates?

Answer 13

Autotrophs use photosynthesis to convert carbon dioxide (CO2) into carbohydrates and other carbon compounds, utilizing energy from sunlight.

Question 14

What forms of carbon are present in aquatic ecosystems?

Answer 14

In aquatic ecosystems, carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.

Question 15

How does carbon dioxide enter autotrophs?

Answer 15

Carbon dioxide diffuses from the atmosphere or water directly into autotrophs, where it’s used for photosynthesis.

Question 16

How is carbon dioxide produced and released by organisms?

Answer 16

Carbon dioxide is produced by respiration as a metabolic waste product and diffuses out of organisms into the atmosphere or water.

Question 17

How is methane produced in anaerobic conditions?

Answer 17

Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and can diffuse into the atmosphere or accumulate in the ground.

Question 18

What happens to methane in the atmosphere?

Answer 18

Methane is oxidised to carbon dioxide and water in the atmosphere through reactions with hydroxyl radicals.

Question 19

How does peat form?

Answer 19

Peat forms in waterlogged soils where organic matter is not fully decomposed due to acidic and/or anaerobic conditions.

Question 20

How were coal, oil, and gas formed from organic matter?

Answer 20

Partially decomposed organic matter from past geological eras was converted into coal, or into oil and gas, which then accumulated in porous rocks.

Question 21

How is carbon dioxide produced by the combustion process?

Answer 21

Carbon dioxide is produced by the combustion of biomass and fossilised organic matter, adding CO2 to the atmosphere.

Question 22

How do certain animals contribute to carbon cycling through their hard parts?

Answer 22

Reef-building corals and molluscs have hard parts composed of calcium carbonate, which can become fossilised in limestone, contributing to geological carbon stores.

Question 23

What elements are essential to include in a diagram of the carbon cycle?

Answer 23

Essential elements include major carbon reservoirs like the atmosphere, oceans, and forests, and processes like photosynthesis, respiration, combustion, and sedimentation.

Question 24

What unit is used to estimate carbon fluxes in the carbon cycle, and what does it represent?

Answer 24

Carbon fluxes are estimated in gigatonnes (Gt), representing the movement of carbon between reservoirs in the carbon cycle.

Question 25

How do air monitoring stations like Mauna Loa Observatory contribute to understanding the carbon cycle?

Answer 25

They provide continuous, accurate measurements of atmospheric CO2, helping to analyze annual fluctuations and long-term climate trends.