nitrogen cycle

Question 1

saprobiants role in decomposition

Answer 1

Bacteria and fungi that break down organic to inorganic molecules and ions.

Question 2

How do saprobionts feed themselves.

Answer 2

Via extracellular digestion. secrete digestive enzymes and absorb soluble nutrients released.

Question 3

ammonification

Answer 3

decomposition (saprobiants) of nitrogen containing organic compounds from urea and waste products of dead animals/ plants into NH4+ ions.

Question 4

Nitrification

Answer 4

NH4+ ions are converted to N02- (nitrite) then to N03- (nitrate) ions by nitrifying bacteria. The nitrifying bacteria need aerobic conditions (C02) to be able to aerobically respire and oxidise N02- to N03-.

Question 5

Assimilation

Answer 5

Plants take Nitrate ions into root hair cells via active transport - the plant uses these ions to build new nitrogen containing organic molecules.

Question 6

Denitrification

Answer 6

Nitrate ions are converted to nitrogen gas by denitrifying bacteria -> Need anaerobic conditions eg: waterlogged soils.

Question 7

Nitrogen fixing bacteria

Answer 7

live in soil, root nodules of lagoonous plants. Takes nitrogen gas from atmosphere and converts into ammonium ions.

Question 8

mycorrhizae

Answer 8

fungi at roots of plants - grow around root system increasing the SA for absorption of water and mineral ions for plants.

Mutualistic relationship as micorrhizae receives sugars from plant

Question 9

natural fertilisers

Answer 9

organic matter (mature, dead and decaying remains of plants and animals).

Question 10

artificial fertilisers

Answer 10

pure, inorganic ions blended together to give the appropriate balance of mineral ions for a particular crop.

Question 11

leaching

Answer 11

lost of soluble substances (PO43-) from top layer of the soil when water drains through.

Question 12

when is leaching more likely to occur?

Answer 12

if fertiliser is applied just before heavy rainfall - gets washed away as hasn’t been enough time for ions to take in ions from their roots via active transport.

Question 13

eutrophication

Answer 13

Leaching of XS mineral ions from fertilisers into waterways. The increase of mineral ions stimulates rapid growth for algae in pods and rivers. (agal bloom). Rapid growth blocks plants below from reaching sunlight - can’t photosynthesis and die. The bacteria in the pond feed/ decompose dead plant matter and carry out aerobic respiration and therefore oxygen concentration decreases so fish and other organisms die as not enough oxygen available. - decomposition reoccurs causing death of the ecosystem.