nutrient cycles

Question 1

`describe the action of microorganisms in the nitrogen cycle

Answer 1

proteins / amino acids / dna converted into ammonium compounds / ammonia by saprobionts
ammonia into nitrites
nitrite into nitrates
by nitrifying bacteria
nitrogen gas to ammonia
by nitrogen fixing bacteria

Question 2

Describe the phosphorus cycle whilst highlighting the role of microorganisms

Answer 2

phosphate ions from phospholipids, DNA and RNA
phosphate ions in oceans and soil
absorbed by plants or sedimentation so phosphate ions in rocks
consumed by animals
excretion so phosphate ions in oceans and soil
excretion and decomposition - phosphate ions from waste and remains
erosion - phosphate ions in ocean and salt
deposition phosphate ions in rock - phosphate ions in oceans and soils

Question 3

Describe the mutualistic relationship of mycorrhizae and plants

Answer 3

Mycorrhizae benefit plants by:
Increasing the total surface area of the plants root
Increasing the absorption of water
Increasing the absorption of mineral ions e.g. phosphates and nitrates

plant benefit mycorrhizae by
Producing organic molecules, sucrose and amino acids, made from photosynthesis that mycorrhizae use to (grow/respire)

Question 4

Suggest reasons for conserving named ecosystem eg woodland.

Answer 4

1. Conserving / protecting habitats and niches;
2. Conserving / protecting species
3. maintains / increases biodiversity
4. Reduces global warming / climate change carbon dioxide removed
5. Source of medicines
6. More tourism

Question 5

nitrification

Answer 5

nitrifying bacteria
ammonia to nitrites
nitrites to nitrates
NH3 -> NO2- -> NO3-

Question 6

denitrification

Answer 6

denitrifying bacteria
nitrates to nitrogen gas (unusable form)
NO3- -> N2
also nitrates to nitrites

Question 7

nitrogen fixation

Answer 7

nitrogen fixation bacteria
nitrogen gas to ammonia

Question 8

decomposition

Answer 8

sabrobionts
nitrogen containing compounds to ammonia

Question 9

what molecules contain nitrogen

Answer 9

proteins , amino acids , ATP , nucleic acids

Question 10

environmental impact of using fertilisers

Answer 10

reduced species variety
environmental issues
leaching

Question 11

eutrophication

Answer 11

-nitrates washed away into water courses and build up
-high conc of ions causes rapid growth of algal bloom
-algae block light and less light penetrates the water - less photosynthesis
-oxygen depletes
-plants under the surface cant photosynthesise and die off
-sapriobionts decompose dead plants using even more o2 so o2 further depletes
-o2 levels reach a point where no life is possible
-fish and other organisms die
-death of the ecosystem

Question 12

advantages and disadvantages of natural and artificial fertilisers

Answer 12

natural
-cheaper and often free for farmers
-mineral and proportions cannot be controlled

artificial
-contain chemicals pf exact proportions
-have greater environmental effects eg leaching