Nutrient Cycles Flashcards
A simple nutrient cycle
The Phosphorus Cycle
Phosphate ions in rocks are released into the soil by __________
Phosphate ions are taken into _________ through the roots. ____________ increase the rate at which the ___________ can be assimilated
Phosphate ions are transferred through the ________ _______
Phosphate ions are lost from animals in _______ products
When plants and animals died, ____________ break down the __________ compounds releasing phosphate ions into the soil for ___________ by plants. These microorganisms also release the _____________ ions from ________ and faeces.
___________ of rocks releases phosphate ions into seas, lakes and ________. These are taken up by aquatic producers such as _______.
Waste products of birds (________) contains a high proportion of phosphate ions. ________ returns a significant amount of phosphate to soils, particularly in coastal areas. _______ can be used as natural _____________.
Phosphate ions in rocks are released into the soil by weathering.
Phosphate ions are taken into plants through the roots. Mycorrhizae increase the rate at which the phosphorus can be assimilated
Phosphate ions are transferred through the Food chain.
Phosphate ions are lost from animals in waste products
When plants and animals died, saprobionts break down the organic compounds releasing phosphate ions into the soil for assimilation by plants. These microorganisms also release the phosphate ions from urine and faeces.
Weathering of rocks releases phosphate ions into seas, lakes and rivers. These are taken up by aquatic producers such as algae.
Waste products of birds (Guano) contains a high proportion of phosphate ions. Guano returns a significant amount of phosphate to soils, particularly in coastal areas. Guano can be used as natural Fertiliser.
Since 1965 there has been a steady rise in the phosphate concentration in the water of Lake Windermere. Scientists have monitored the phosphate concentration and plant biomass over a period of time. The results are shown in the graphs.
(a) Suggest one source of the phosphate in the lake.
(a) Fertilisers / detergents / slurry / manure / sewage / faeces;
Since 1965 there has been a steady rise in the phosphate concentration in the water of Lake Windermere. Scientists have monitored the phosphate concentration and plant biomass over a period of time. The results are shown in the graphs.
(a) Suggest one source of the phosphate in the lake.
(a) Fertilisers / detergents / slurry / manure / sewage / faeces;
(c) From these graphs, a student concluded that changes in phosphate concentration caused changes in plant biomass. Explain why this conclusion may not be valid. (2)
(d) Between 1982 and 1992 the number of fish in the lake decreased. Explain how the change in phosphate concentration may have resulted in this decrease in the fish population. (6)
(c) Have continuous data for phosphate but not for biomass;Effect of named factor explained;
2
(d) 1.Increased phosphate causes increase in plant growth / algal bloom;
2.Plants (cover surface and) block out light so plants (under surface) die;
3.Increase in (aerobic) bacteria / decomposers (which break down plants);
4.Bacteria / decomposers use up oxygen / reduce oxygen conc. in water;
5.In respiration;
6.Plants unable to photosynthesise so less oxygen produced;
Microorganisms
These are an important part of food webs and the ecosystem.
Many are saprobionts
They feed on dead plants and animals, and their waste products
This allows important chemical elements to be recycled
Detritivore
An organism that feeds on detritus or organic waste. E.g. millipedes, woodlice, earthworms.
By consuming dead organic matter they speed up decomposition by increasing the surface area available to the decomposers.
Mycorrhizae
Some fungi form symbiotic relationships with the roots of plants. These relationships are known as Mycorrhizae.
The fungi are made of long thin strands called hyphae. These connect to the plant roots, greatly increasing the surface area of the plant root system. This makes absorption of water and ions e.g. phosphorous from the soil more efficient. The fungi obtain organic compounds e.g. glucose form the plant.
Symbiosis
A symbiotic relationship is when two species live very closely together and one or both species depend on the other for survival.
Symbiotic Relationships
Guano
Waste produced by seabirds is known as guano
Weathering
Nitrogen Fixation
Nitrogen ___ is changed into ____________ ____by _________ __________ bacteria called Rhizobium
Rhizobium are found in the root nodules of leguminous plants e.g. peas, beans, clover
They form a _________relationship
Bacteria provide the plant with N- compounds
Plant provides bacteria with ________________
Nitrogen gas is changed into ammonium ions by nitrogen fixing bacteria called Rhizobium
Rhizobium are found in the root nodules of leguminous plants e.g. peas, beans, clover
They form a mutualistic relationship
Bacteria provide the plant with N- compounds
Plant provides bacteria with carbohydrates
Nitrogen Fixing Bacteria
Rhizobium bacteria are found in _____ ________ of leguminous plants. Other nitrogen fixing bacteria are _________in the soil
Rhizobium bacteria are found in root nodules of leguminous plants. Other nitrogen fixing bacteria are present in the soil
Eutrophication exam style answer
1) Algae blooms block light
2) No photosynthesis, so plants die.
3) Saprobiotic decomposition occurs.
4) Microorganisms respire aerobically (use up oxygen)
5) Less oxygen for fish to respire, therefore they die
6) Increase in anaerobic microorganisms; release hydrogen sulphide/ nitrates/ toxic waste
