Biogeochemical Cylces

Question 1

What happens during photosynthesis in the carbon cycle?

Answer 1

Photosynthesis captures light using pavement such as chlorophyll converting low energy substances such as carbon dioxide and water into high energy carbohydrates which may be converted into other substances such as proteins and lipids

Question 2

What happens during respiration in the carbon cycle?

Answer 2

Respiration releases the energy that was captured during photosynthesis which is then used to drive metabolic processes aerobic respiration returns carbon dioxide into the atmosphere
- Anaerobic respiration usually returns the carbon into the atmosphere as methane

Question 3

What happens to carbon in food webs of the carbon cycle?

Answer 3

Some of the carbohydrates, proteins and lipids produced by plants are eaten by herbal was which may then be eaten by carnivals these feeding relationships combined to make food webs

Question 4

What is fossilisation in the carbon cycle?

Answer 4

Incomplete decomposition of dead organic matter often under anaerobic conditions can produce substances that form long-term carbon stores such as fossil fuels, some organisms like mollusks corals and plant tonic organisms produce exoskeletons that include calcium carbonate
- This may produce rocks such as limestone which contain most of the carbon of the lithosphere

Question 5

What happens during combustion in the carbon cycle?

Answer 5

The burning of organic materials releases carbon dioxide natural flyers in forest and grassland might be started by lightning

Question 6

How do humans affect the carbon cycle by changing photosynthesis?

Answer 6

• deforestation reduces the movement of carbon from the atmosphere into biomass
• Marine pollution of toxic materials can reduce phytoplankton populations reducing the absorption of dissolved carbon dioxide leading to higher atmospheric carbon dioxide levels
• How do you live on the underside of sea surround Antarctica? Some of the carbon dioxide they absorb sinks to the sea bed in the thesis of crow that eat the Algae if less sea ice is available less CO2 may be removed from the sea

Question 7

How do humans affect the carbon cycle by changing aerobic respiration

Answer 7

Carbon in dead organic matter in the soil is gradually released as CO2 by the aerobic respiration of soil organisms like bacteria and fungi
- Ploughing increases the oxygen supplied to the decomposers living in the soil also aerobic decomposition takes place more rapidly leaving the amount of carbon in the soil reduced and the amount of carbon in the atmosphere increased

Question 8

How are humans affecting the carbon cycle by changing an anaerobic respiration?

Answer 8

With the absence of oxygen respiration by anaerobic organisms releases methane gas
Several anaerobic environments are produced by human activities:
- Rice padi fields
- Landfill sites
- Livestock intestines
- Waterlogged fields
- Marshlands
- peat bogs

Question 9

How are humans affecting the carbon cycle by changing the carbonic acid concentration in the sea?

Answer 9

• dissolve carbon dioxide is in equilibrium with carbonic acid which associates deform hydrogen carbonate and hydrogen ions. If there is an increase in hydrogen ions it will reduce the pH of the water.
• As atmospheric carbon dioxide concentrations rise dissolved carbon dioxide concentrations increase which therefore increases the hydrogen iron concentrations and makes the sea more acidic

Question 10

How are humans affecting the carbon cycle from methane releases from fossil fuels?

Answer 10

Maybe they may be released into the atmosphere during foul fuel extraction

Question 11

How humans affecting the carbon cycle by combustion?

Answer 11

The combustion of fossil fuels and Word releases large amounts of CO2 into the atmosphere

Question 12

How are humans affecting the carbon cycle by biomass movements?

Answer 12

• The addition of compost or mulch to improve soil fertility
• Deforestation and crop harvesting needing to reduce soil organic matter and soil erosion
• The movement of biomes into the sea when sewage is discharged
• Movement of marine biome mass into terrestrial system by fishing or aquaculture

Question 13

How does conservation of biomass carbon stores sustainably manage the carbon cycle?

Answer 13

Habitats such as peat bogs and forests contain huge amounts of carbon, protecting these for exploitation, or managing land-uses change, is necessary to prevent any further carbon dioxide releases

Question 14

How can the use of alternatives to fossil fuels sustainably manage the carbon cycle?

Answer 14

Renewable energy resources and nuclear power produce lower carbon dioxide emissions than fossil fuels

Question 15

How can carbon sequestration sustainably manage the carbon cycle?

Answer 15

Large scale tree planting could remove a lot of CO2 from the atmosphere and slow down or reverse rising CO2 levels
- full grown trees so not have anymore net storage of carbon but so act as a carbon reservoir

Question 17

How can carbon capture and storage (CCS) sustainably manage the carbon cycle?

Answer 17

This involves capturing carbon, usually as CO2, so that is is not released into the atmosphere
Done by pre and post combustion technology as well as storage

Question 18

What is pre-combustion technology?

Answer 18

Changing the fuel used or how it is combusted
- gasification converts a fuel such as coal into gaseous hydrogen and CO2, the CO2 can be removed for storage, then the hydrogen can be distributed for use in vehicles, homes or industry. When burnt the exhaust gases contain water vapour only
- oxy-fuel combustion systems use pure oxygen so that only CO2 and water vapour are produced, water vapour can be removed by cooling the gases so that it condenses, capture of the CO2 is then much easier as it is not mixed with other gases

Question 19

What is post-combustion technology?

Answer 19

CO2 can be removed using several methods:
- dissolving it in a solvent
- high pressure membrane filtration
- adsorption/desorption processes
- cryogenic separation
- graphene adsorption
Can be expensive

Question 20

What is nitrogen ionisation in the nitrogen cycle?

Answer 20

Processes such as lightening and meteor trails provide the energy for atmospheric nitrogen ans oxygen to react and produce oxides of nitrogen

Question 21

What is nitrogen fixation in the nitrogen cycle?

Answer 21

Some microorganisms can chemically reduce nitrogen to ammonia, like free-living bacteria in the soil or they may live symbiotically in the root nodules of legumes

Question 22

How are food chains involved in the nitrogen cycle?

Answer 22

Nitrogen passes between organisms as amino acids and proteins in food

Question 23

What is nitrification in the nitrogen cycle?

Answer 23

Nitrification involves the oxidation of ammonium ions to nitrates, then nitrites by nitrifying bacteria in the soil

Question 24

What is denitrification in the nitrogen cycle?

Answer 24

The chemical reduction of nitrates in soil to nitrogen and nitrogen oxide gases, by denitrifying bacteria in the soil, reduced soil fertility
- normally occurs under anaerobic conditions

Question 25

What is leaching in the nitrogen cycle?

Answer 25

The high solubility of nitrates means they are easily leached out of soils into water bodies where they act as nutrients for aquatic plants and algae

Question 26

What is root absorption in the nitrogen cycle?

Answer 26

Plants assimilate nitrogen soluble ions mainly nitrates but also ammonium ions

Question 27

What is ammonification in the nitrogen cycle?

Answer 27

The amino acid groups in proteins are released as ammonium ions by the action of bacteria, fungi, and detritivores as they decompose dead organic matter

Question 28

How does the Haber process impact the nitrogen cycle?

Answer 28

Produces ammonia from nitrogen and hydrogen using an iron catalyst at high temperatures and pressures - use lots of energy - ammonia may be converted to nitrates

Question 30

How does agriculture impact the nitrogen cycle?

Answer 30

- use of nitrate fertilisers may increase leaching and therefore eutrophication - drainage of fields makes the soil more aerobic, increasing the number of aerobic nitrifying bacteria and reduces the number of anaerobic denitrifying bacteria - soil disturbance by ploughing increases the rate of decomposition of dead organic matter which releases more nitrogen oxides into the atmosphere - leguminous plants such as peas and beans may be grown to increase levels of nitrogen compounds in the soil for crops to absorb

Question 31

How is pollution impacting the nitrogen cycle?

Answer 31

Oxides of nitrogen are released into the atmosphere by combustion processes an may subsequently increase the quantity of nitrates washed into the soil by rain

Question 32

How can control of combustion processes sustainably manage the nitrogen cycle?

Answer 32

Reduction in use of fossil fuels would reduce NOx releases, could be a deliberate choice or caused by the depletion of fossil fuel supplies - adopting principles of Circular Economy would result in the use of more low-temperature manufacturing processes e.g. the use of polymers produced by living organisms rather than high-temperatures processe using fossil fuels

Question 33

How does control of NOx releases sustainably manage the nitrogen cycle?

Answer 33

- reduced using post-combustion processes such as catalytic converters and urea sprays

Question 34

How can management of biological wastes sustainably manage the nitrogen cycle?

Answer 34

- decomposition of biological wastes releases ammonium ions as the amino acids in proteins are de-aminated, enzymes produced by bacteria remove amino groups which dissolve as ammonium ions

Question 35

How can eutrophication sustainably manage the nitrogen cycle?

Answer 35

- bio wastes may be washed into water bodies by runoff or they may deliberately be dumped there, ammonium compounds are converted to nitrites and nitrates which can cause eutrophication in water bodies

Question 36

How can organic fertilisers sustainably manage the nitrogen cycle?

Answer 36

Manure, sewage, and food production wastes may be used as organic fertilisers to increase nutrient and humus levels

Question 37

How can management of soil processes sustainably manage the nitrogen cycle?

Answer 37

Increasing soil nitrate levels: - cultivation of legume crops - crop rotation - minimal use of pesticides that harm soil biota - control of nitrate leaching - not applying fertilisers during rain - use of low solubility fertiliser - use of low-tillage techniques - uncultivated buffer strips left along rivers - minimal use of nitrate fertiliser where leaching into aquifers is likely

Question 38

How is phosphorus absorbed by roots in the phosphorus cycle?

Answer 38

Most plants have a symbiotic relationship with mycorrhizal fungi, which are extensive networks of fungal hyphae in the soil which increases the surface area for phosphate absorption

Question 39

How is phosphorus decomposed in the phosphorus cycle?

Answer 39

Breakdown of phosphorylated proteins in dead organic matter releases phosphates that are often made more soluble by soil microbes so they can be absorbed by plants

Question 40

How is sedimentation involved in the phosphorus cycle?

Answer 40

Phosphorus in organisms that die and become incorporated into sedimentation may no longer be available to other organisms, such as planktonic organisms that die and sink to the ocean floor, reduces the productivity of the surface waters of oceans because phosphorus availability is often a limiting factor

Question 41

How is mountain building and weathering part of the phosphorus cycle?

Answer 41

Process that mobilise phosphorus and make it available to living organisms are often slow, phosphorus in marine sediments may not become available again until continental drift forms new mountains ranges and weathering of rocks releases the phosphates

Question 42

How does mining of phosphate rocks impact the phosphorus cycle?

Answer 42

Most phosphorus is mined as calcium phosphate the treated t p produce ammonium phosphate which is more soluble - large accumulations of bird droppings were mined for the ammonium phosphates they contained, these deposits built up in dry ares such as Peru

Question 43

How does fertiliser use impact the phosphorus cycle?

Answer 43

Use of fertilisers mobilises phosphorus compound into the environment in more soluble forms, increasing crop production but can also contribute to eutrophication

Question 44

How can the phosphate cycle be sustainably managed?

Answer 44

- shortage of phosphates is the limiting factor on crop productivity for large areas of farmland, availability of phosphates is reduced by the removal of biomass during harvesting and loss phosphates with eroded soil, maintaining future supplies of phosphates to compensate for these losses by mining rock phosphates is unsustainable - biological wastes should be used as fertilisers to maintain phosphate nutrient availability - crop breeding programmes are increasing the efficiency of phosphate absorption by crops