Biogeochemical cycles

Question 1

definition of biogeochemical cycle

Answer 1

interlined processes involving living organisms that all materials to be recycled and repeatedly reused (prevents build up of waste)

Question 2

Name the 3 human actions that affect photosynthesis in the carbon cycle + explain

Answer 2

marine pollution = decrease phytoplankton pop. less CO2 absorbed, more C in atmo.
Afforestation = more photo., less C in atmo.
Deforestation = less photo., increase C in atmo.

Question 3

Name the 3 biogeochemical cycles

Answer 3

carbon
nitrogen
phosphorus

Question 4

Name the human action that affects changes to aerobic respiration in the carbon cycle

Answer 4

soil disturbance/ploughing = increase aeration, increase aerobic respiration for organisms, more DOM

Question 5

Drainage of marshes and destruction of peat bogs lead to…

Answer 5

more CH4 being released into atmo. CH4 oxidised to become CO2

Question 6

Name 3 human actions that increase CH4 release

Answer 6

Cattle farming, padi fields, anaerobic respiration in landfill

Question 7

Name 3 knock on effects of climate change on the carbon cycle

Answer 7

melting permafrost = releases CH4, oxidises: CO2
increased temps =
negative feedback: increase rate of photo. decrease carbon
positive feedback: increase decomposition, C released
ocean acidification = more CO2 being dissolved into oceans

Question 8

Ocean acidification is due to…

Answer 8

carbonic acid being created by CO2 being dissolved in the ocean from any human activity that releases CO2 . More H+ ions = more acidic

Question 9

name 5 ways to sustainably manage carbon cycle

Answer 9

• alternative to fossil fuels
• conservation of biomass
• carbon sequestration and CCS
• matching afforestation to deforestation
• increasing soil organic matter (main carbon sink of soil)

Question 10

Name the 2 different pre-combustion tech (CCS)

Answer 10

1. gasification = converts fuel into CO2+H. CO2 removed. H used as fuel
2. Oxy-fuel combustion systems = combustion of fuel in pure O, only H2O vapour and CO2 produced (easier to separate)

Question 11

Post-combustion tech (CCS)

Answer 11

removing CO2 from exhausts through 3 different methods

Question 12

Name the 3 methods of Post-combustion tech (CCS)

Answer 12

1. high pressure CH4 filtration
2. Dissolving CO2 in solvent
3. Cryogenic (low temp) separation

Question 13

Name the 2 different ways carbon can be stored (CCS)

Answer 13

1. normally stored underground i.e. depleted aquifers

2. or used to aid oil recovery (secondary oil recovery)

Question 14

In the Carbon cycle name 2 processes that are aerobic

Answer 14

plants and animals respiring aerobically. Phytoplankton respiring aerobically

Question 15

for the carbon cycle: crop removal _______ the amount of DOM

Answer 15

decreases

Question 16

name at least 2 of the 4 reasons why organisms need nitrogen

Answer 16

to synthesise:

ATP, DNA, Proteins, Chlorophyll

Question 17

what is nitrogen fixation + what carries it out

Answer 17

• taking atmospheric N into the soil
• Produces ammonia
  + done by nitrogen fixing bacteria

Question 18

what is ammonification + what carries it out

Answer 18

• decomposition of DOM
• produces ammonia
  + done by decomposers

Question 19

what is nitrification + what carries it out

Answer 19

• converting ammonia into nitrite then into nitrate
• nitrate absorbed by plants
  + done by nitrifying bacteria

Question 20

what is denitrification + what carries it out

Answer 20

• reducing nitrate into N and NOx gases
• N released back into atmo.
  + done by denitrifying bacteria

Question 21

what is leaching

Answer 21

• nitrates leach (soluble so wash out of soil)
• leads to loss of nutrients
• can act as nutrients for aquatic organisms in water bodies

Question 22

Name the 7 ways humans impact the nitrogen cycle

Answer 22

haber process 
growing legumes 
water logging 
sewage disposal 
combustion processes 
drainage/ploughing 
leaving crop residue after harvest

Question 23

what is the haber process? and how does it impact the N cycle

Answer 23

• industrial process to produce ammonia for agricultural fertilisers
• artificial fixation of atmospheric N to ammonia
• ammonia can be converted to nitrates
  + increases movement of atmo. N to ammonia/nitrate

Question 24

How does growing legumes impact N cycle

Answer 24

• legumes have nitrifying bacteria in their root nodules (increase fixation)
  + increase nitrates in soil

Question 25

How does drainage/ploughing impact N cycle

Answer 25

- aeration of soil - produces aerobic environment so increase in aerobic processes i.e. fixation and nitrification - decreases anaerobic processes: less denitrification (less N going to atmo.)

Question 26

how does sewage disposal impact N cycle

Answer 26

- increase nitrate movements (leaching) into H2O bodies + can cause eutrophication: increase algae, reduced O2 as plants beneath algae die due to blocked sunlight, decomposition occurs (O2 depleted even more), produces dead zones

Question 27

how does combustion processes impact N cycle

Answer 27

``` - N + O = NOx + increase nitrate in soil (when rains) + cause photochemical smogs (NOx reacts with UV): increase risks of respiratory infections i.e. asthma/heart disease + NOx (greenhouse gas) = global warming + NOx toxic and produce acid rain ```

Question 28

how does leaving crop residue impact N cycle

Answer 28

addition of nitrates to soil

Question 29

how does waterlogging impact the N cycle

Answer 29

example: growing rice in padi fields - increase anaerobic conditions + increase denitrification = decrease nitrates in soil

Question 30

Name all of the aerobic processes in the N cycle

Answer 30

fixation ammonification Nitrification

Question 31

Name all the anaerobic processes in the N cycle

Answer 31

denitrification

Question 32

name the 4 methods f counteracting anthropogenic N movements

Answer 32

reduced combustion processes use of natural fixation processes (instead of haber) management of biological waste methods to reduce soil nitrate leaching

Question 33

how does reduced combustion processes counteract N movements

Answer 33

- reduce use of fossil fuels = less NOx release + done by depleting fossil fuel supplies and switching to renewable energy - use of circular economy principles (polymers produced by living organisms with low temps notnigh temps with fossil fuels) - use of catalytic converters

Question 34

how does using natural fixation processes instead of haber counteract N movements

Answer 34

using organic fertilisers, not storing waste near waterways (contamination)

Question 35

methods to reduce nitrate leaching (counteracting N movements)

Answer 35

planting legume crops apply fertilisers when not raining (less leaching) use of low solubility fertilisers i.e. urea 'buffer strips' near waterways prevent leaching

Question 36

Why do organisms need phosphorus?

Answer 36

DNA, RNA, Phospholipids, ATP, Bones

Question 37

Name the 2 differences of the phosphorus cycle compared to N and C cycle

Answer 37

- no phosphorus in atmo. - Phosphates not very soluble in H2O (both make cycle slower compared to C/N cycles)

Question 38

name the 3 impacts humans have on the P cycle

Answer 38

fertiliser use mining of phosphate rocks use of guano deposits

Question 39

how does fertiliser use impact P cycle

Answer 39

- increase crop production - leaching can cause eutrophication - mobilises phosphorus in a more soluble form

Question 40

how does mining of phosphate rocks impact P cycle

Answer 40

- phosphorus mined as calcium phosphate - treated to become ammonium phosphate (more soluble) - used to make fertiliser

Question 41

how do the use of guano deposits impact P cycle

Answer 41

1. plankton absorbs P 2. fish eat plankton 3. birds eat fish 4. bird droppings rich in P (guano) 5. humans collect guano organic fertiliser

Question 42

Name the methods in which the P cycle can be sustainably managed

Answer 42

``` use of organic fertilisers choosing a crop with less need for P Crop rotation Crops which absorb P more efficiently Having suitable conditions for mycorrhizal fungi ```

Question 43

name the method that is sustainable than the use of artificial fertiliser

Answer 43

using organic fertilisers

Question 44

name the 2 methods that make use of the fact that crops need more of one mineral than the other

Answer 44

- choosing crop with less need for P | - crop rotation

Question 45

name the 2 methods that increases phosphate uptake

Answer 45

- crops that absorb P more efficiently | - suitable conditions for mycorrhizal fungi