Ecology: Nitrogen Cycle, Minerals And Eutrophication Flashcards
Plants and nitrogen
Plants absorb nitrogen in form of nitrates. They then convert into amino acids and then made into protein to help plant grow.
Nitrogen cycle relies on bacteria
Decay
Feeds on dead organisms and waste materials releasing ammonia
Nitrifying
Convert ammonia to nitrates
Denitrifying
Convert nitrates to nitrogen gas
Nitrogen fixing
Convert nitrogen gas into nitrates
Decay, nitrifying and nitrogen fixing
bacteria all require oxygen to function efficiently.
This is why well aerated soils are important to farmer when growing crops
Denitrification
Reduces amount of nitrate in soil. Denitrifying bacteria prefer anaerobic conditions(no oxygen)
Such as those created due to water logging following prolonged periods due to heavy rain
Root hairs cells
All minerals are absorbed from the soil in solution via these roots
Major adaptation in root hair cells
The adaptation is the presence of an extension of the cell that projects outwards from the cell into the soil.
This greatly increases the surface area of the cell improving the rate of water and mineral absorption
Active uptake
The process of absorbing minerals from soil relies on active uptake.
This process moves substances against the concentration gradient.
Active uptake requires energy from respiration. This is why roots must have a sufficient supply of oxygen (glucose)
Nitrates
Growth and development:Needed to make amino acids the building blocks of protein
Deficiency:stunted growth
Calcium
Growth and development: a component of cell walls
Deficiency: no growth at all, new cells can’t form
Magnesium
Growth and development: a compliment of the chlorophyll molecules
Deficiency: leaves appear yellowed
Natural fertilisers advantages
- less soluble than artificial fertiliser so less will be lost by leaching and runoff into waterways
- improves soil quality by adding to the humus content of the soil
Natural fertilisers disadvantages
- difficult to store and spread
- difficult to know the mineral composition exactly
Artificial fertiliser advantages
- easier to stores
- can be applied in a more controlled manner
Artificial fertiliser disadvantage
- soluble so can be easily washed away creating pollution problems
- has to be purchased
Slurry
Faeces and urine from farm animals (usually cattle)
Compost
Food waste (vegetable peelings)
Manure
Animal faeces
Eutrophication
This is where no life exist due to lack of oxygen. It is a common form of water pollution found close to agricultural land.
It often follows a sudden increase in concentration of minerals in water. ( fertiliser runoff due to heavy rain)
Problem with the growth of algae
The presence of minerals lead to increase rate of growth.
These form a blanket like layer on the surface if the after preventing light from reaching plants beneath. These plants eventually die.
The decomposition of these plants uses up (DEPLETES) oxygen in the water and means fish and animals cannot survive in the water.
How to reduce eutrophication
- use natural fertiliser
- apply when dry/don’t use it when heavy rain is forecast
- don’t apply close to river or ditch
- only use when necessary
Other pollutants which has the same effect as fertiliser runoff
Household sewage
Why is eutrophication more common in slow moving water (ponds)
The minerals become more concentrated
