The Nutrient Cycles
0.0 / 5
- Created by: Betsy_2018
- Created on: 31-12-17 17:28
Abstract
- nutrient is taken up by a producer as a simple, inorganic molecule
- producer incorporates the nutrient into complex organic molecules
- producer is eaten
- producers' nutrient is passed on to consumers
- nutrient passes along a food chain
- consumers die
- consumers' molecules are broken down by saprobiontic microorganisms
- saprobiontic organisms release the nutrient in its original form
- the cycle is then complete
- without decomposers, the cycle would back up (the nutrients would remain locked up)
1 of 11
Nitrogen
- 78% of air on Earth
- gas at room temperature
- used for proteins, nucleic acids, amino acids and DNA
- many organisms use it due to its non-reactivity
- obtained by animals by eating plants
- enter plant by active transport in the roots, as nitrate ions (NO3-)
- nitrate ions are very soluble (easily leach through soil)
- ions are replenished by the decomposition of organisms
- there are very few sources of nitrate ions (usually from decomposition)
- nitrate ion concentration can be increased in agriculture by using fertilisers
2 of 11
STEP 1: Nitrogen Fixation
What?
- fixes nitrogen gas (N2) to nitrogen compounds (organic nitrogen)
- ammonia is often produced (NH3)
- ammonia is used for amino acid production
How?
- free-living bacteria
- reduce gasesous nitrogen to NH4+
- produce amino acids
- released from bacteria when they die and decay (into the soil)
- mutualistic nitrogen-fixing bacteria
- live in nodules on the roots of plants
- produce amino acids from gaseous nitrigen, which they give to plants
- plants repay them with carbohydrates
- lightning
- industrially
3 of 11
STEP 2: Ammonification
What?
- production of ammonium ions from nitrogen compounds (ammonia)
- from urea (excess amino acids), proteins, nucleic acids and vitamins from faeces
- ammonium ions are NH4+
How?
- saprobiontic microorganisms
- feed off urine, faeces and dead organisms (nitrogenous compounds)
- release ammonia
- returm nitrogen to a non-living form
- become ammonium ions in the soil
4 of 11
STEP 3: Nitrification
What?
- oxidation of ammonium ions to nitrite ions (NO2-)
- oxidation of nitrite ions to nitrate ions (NO3-)
How?
- free-living nitrifying bacteria
- need well aeriated soil to respire and survive
- obtain their energy from chemical reactions involving inorganic ions
- house oxidation of ammonium ions and nitrite ions
Possibilities?
- taken into plant roots by active transport
- released upon plant/consumer death
- converted back to nitrogen gas
5 of 11
STEP 4: Denitrification
What?
- nitrate ions are converted to nitrogen gas
How?
- anaerobic denitrifying bacteria
- soil becomes waterlogged, causing low O2 levels (air can not aeriate)
- aerobic bacteria decrease
- anaerobic bacteria increase
6 of 11
Phosphorus
- comes from a mineral
- comes mostly as phosphate ions (PO4^3-) in sedimentary
- phosphorylates molecules
- part ATP and DNA, RNA, etc
- in bones and teeth
- red phosphorus
- used in fertilisers, detergents, steel production and matches
- non-toxic
- white phosphorus
- used in flares
- glows in the dark
- burns skin
- poisonous
- no gaseous exchange in its cycle
7 of 11
STEP 1: Sedimentary Rock
- sedimentary rock is always formed in aquatic environments
- oceans and lakes
- sedimentary rock is made up bone fragments, bones, shells, molluscs and plants (coal)
- is 8% of the Earth's crust
- brought to the surface by geological uplifting of rocks
- rock is eroded and dissolved in the soil
8 of 11
STEP 2: Uptake
- plants obtain phosphorus from the soil
- via active transport
- through roots
- animals eat the plants and obtain phosphorus
- use it for ATP, DNA, etc
- primary consumers are eaten by secondary
- along a food chain
9 of 11
STEP 3: Release
- animals die
- animals are decomposed by decomposers
- phosphates are released into water or soil
- remaining phosphates in excreta are released by decomposition
- phosphates are transported down stream
- phosphates are transported to lakes and oceans to form new sedimentary rock
10 of 11
Myocorrhizae
- associations between certain types of fungi and the roots of plants
- a mutualistic relationship
- fungi acts as an extension of the plant's root system
- increases its surface area of the absorption surface for mineral ions
- fungi changes the composition of the soil (makes it spongy)
- holds more water to resist droughts
- holds extra minerals
- insoluble phosphorus requires vast root system, without this aid
- plays a vital role in phosphorus absorption in uncultivated soil
- fungi supplies plants with phosphorus
- fungi receives sugars and amino acids in return
11 of 11
Related discussions on The Student Room
- Advanced Higher Biology Project Ideas »
- TSR Goes Green: Careers in the Environmental Sector »
- Biology a level question - Ecology »
- AQA Biology essay »
- A-level Biology Study Group 2023-2024 »
- Biological sciences choosing universities »
- What is UCL’s Earth Science BSC like? »
- Good Grades And Experience Are Worthless (Nature Jobs, Science, Humanities) »
- Geography NEA »
- Enviromental Science or Conservation and Ecology »
Similar Biology resources:
2.0 / 5 based on 1 rating
0.0 / 5
2.0 / 5 based on 1 rating
0.0 / 5
0.0 / 5
3.0 / 5 based on 1 rating
5.0 / 5 based on 1 rating
Comments
No comments have yet been made