Topic 5B - Energy Transfer and Nutrient Cycles Flashcards
Importance of nutrient recycling
Finite resources, recycle to not deplete as plants etc need them for growth and function - this is why organisms decompose to not lock up nutrient
3 nutrient cycles
nitrogen, carbon, phosphorus
see samsung notes for carbon cycle
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In a rainforest, explain how Co2 conc. changes over both the day and at different heights (use photosynth. and respiration).
5 marks
- increase CO2 at night, no photosynthesis & all respiration
- more CO2 released linked w/ resp. at night
- in light more uptake of CO2 and increased rate of photosynthesis compared to resp.
- ground level : less photosyn. and more microbes resp.
exam Q booklet for carbon cycle
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What term to use at a level instead of decomposers
Saprobiont (saprobiotic nutrition), decomposers as they respire -
use carbon compounds from decay in resp.
3 things a saprobiont does.
- important extra note *
- Feed /digest remains of dead, and waste material - breaks them down. Name specific compounds broken down, maybe where they maybe found :
- carbs: breaks glycosodic bonds
- proteins: into amino a., peptide band
- lipid: glycerol & fatty acid, ester - Extracellular digestion, enzymes secreted and food digested externally and absorbed. Humans have internal environment for this.
- Breaks down organic molecules into inorganic ions (no carbon in them)
* Fungi like mycorrhizae do saprobiotic nutrition through decomposing and can make nitrates in decaying matter much more quickly available
Some fungi,mycorrhizae, form a symbiotic (close association) relationship with plant roots.
What type of symbiotic relationship is it? What does each party do?
mutualistic - you can look the rest up.
My corrhizal fungi increase SA of roots using hyphae to ^ uptake of water & mineral ions.
Plant let fungi access phloem and get organic groups like sucrose (less reactive for plants than glucose) from photosynthesis and amino acids - allows resp. to release energy and fungi can grow
what are the lang thin strands that mycorrhizae use to connect to roots called?
hyphae
mycorrizhae
very common relationship between fungi and plant roots
abiotic factors affecting survival of mycorrhizae
Moisture, temp, oxygen availability, photosynthesis levels of plant etc
What human activity kills mycorrhizae?
Pollution, soil erosion, and land use (soil distribution) can kill them
How does mycorrhizae benefit the community
Can make plant grow faster as they receive the nutrients first, and they can transfer organic compounds between plants, and can protect plant from pathogens
How do plants absorb nitrogen?
Where is nitrogen used in plants and animals?
By actively transporting it through roots. It’s used in making DNA (nucleic acids), amino a., proteins like enzymes and antibodies, ATP
Difference between nitrites and nitrates?
Nitrates are formed from nitrites when an oxygen molecule is added.
Difference between ammonia and ammonium ions
Ammonia has one less hydrogen atom so isn’t charged (mentioned please frequently)
Watch recap vids on nitrogen cycle
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Nitrogen cycle on drawn notes
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nitrogen fixation and microbe involved.
Aerobic resp.
Nitrogen - fixing bacteria living free in soil or root nodules (these have air pockets with nitrogen) of leguminous plants.
Nitrogen gas is (oxidised?) converted into ammonia, dissolving in water to make ammonium ions in the soil.
Why would farmers use crop rotation with legumes?
Root nodules w/ nitrogen - fixing bac. fertilise soil w/ ammonium ions…. eventually into nitrates available for plant to absorb by active transport.
Soil in farming is usually infertile due to no crops dying, no decomposing - no nutrients recycled
Ammonification and microbes involved.
Aerobic resp.
Dead biomass and waste / urine allow for the proteins / DNA (nitrogen compounds) in them to be released when decomposed by saprobionts.
Ammonium ions formed.
What can farmers add to soil to replace crops that cannot be
left to decompose?
Fertiliser, natural - manure/ urine, or artificial
Nitrification and microbe involved.
Aerobic resp.
OXIDATION of ammonium ions into nitrites and also then nitrates by nitrifying bacteria.
- farmers want to ensure maximum oxygen in soil for this (see farming techinques)
Which bacteria in the nitrogen cycle aerobically respire and which do anaerobically?
Denitrifying bac, anaerobically.
All other bac aerobic resp.
Denitrification and microbe involved
Only anaerobic resp process!
Denitrifying bacteria thrive in low oxygen soil levels and convert nitrates in the soil back into nitrogen gas.
- farmers don’t want nutrients being converted back into the atmosphere, so they will have methods to ensure aerated soil as much as possible to increase growth.
Benefits of ploughing to farmers
Aerates soil: promotes aerobic bacteria (mention) and limits anaerobic denitrifying.
You dig and mix up soil, may add organic matter
Benefits of crop rotation (normal plants)
Helps increase microbial diversity In soil AND rotating every year or so plants that require different nutrients / bac so soil isn’t stripped of specific ones.
Benefits of crop rotation (legume)
Planting legumes for a period of time = nitrogen fixing bacteria in nodules increases the rate of nutrients replenishing, specifically ammonia > ammonium compounds/ ions…. then nitrites > nitrates, so soil isn’t barren.
- can mix them in with other crops so not all same nutrients / ions absorbed : allows soil ion concentrations to recover AND improve fertility.
Benefits of fallow land to farmers
Where previous dead vegetation allowed to die & decompose (natural process of allowing any plants to grow and die).
Restores nitrogen levels as saprobionts decompose them and carry out ammonification from DNA/ proteins in matter into ammonia and then ammonia compounds / ions.
- allows different levels of ions to accumulate for next year’s crops
Benefits of draining water-logged fields to farmers
Ensures that water levels aren’t limiting the oxygen levels in the soil, so increases O2… link to bacteria
- keeps soil fertile (either due to point above, or nitrates not being dissolved and washed away)
! Ensures less denitrifying bacteria in soil (as waterlogged soil isn’t aerated)… STATE what these bacteria do and how it means less nitrates for plant growth
assimilated
taken in (by plants)
Uncultivated land
Likely to have legumes growing, so high rate of nitrogen fixation and fertile soil
suggest how nitrogen cycle may have been altered by human activity
Fertilisers = more nitrates available to plants
( increased nitrate conc. overall)
What is phosphorus used in animals and plants?
DNA, any nucleic acids, phospholipid bilayer, ATP
main sources of phosphorus in the world?
Rocks and also in oceans when rocks dissolved / weathered
in what form is phosphorus found?
organic phosphate in rocks and when dissolved in ocean, phosphate ions made
How does phosphorus get into the food chain?
When phosphate ions dissolve in water, it’s absorbed by soil and assimilated by plants
Guano
The name for large amours of bird excrement, v. common coastal areas.
It can be used as a natural fertiliser as it contains high conc. of phosphate ions to return the large amounts to the soil
2 ways phosphate ions are returned from organisms to soil
Waste products and decomposition/ death
- via ammonification, saprobionts by extracellular digestion, breakdown DNA / ATP, etc, in the waste
