Topic 1.5 Populations & Ecosystems (Recycling Nutrients) Flashcards
1.5
a) Plants make their food via photosynthesis and all consumers acquire their food by eating producers or other consumers. What are detritivores? Why is the role they play so important to the ecosystem?
b) What is the difference between SAPROTROPHIC organisms and DETRITIVORES?
c) The minerals cycle is between _____ factors of an ecosystem and ______ factors of an ecosystem.
a) Detritivores are organisms who feed on dead or decaying matter - this can be plant & animal remains. They break down the organic matter and recycle the nutrients back into the ecosystem. They return vital nutrients back into the soil. Plants then take up these minerals again.
b) Saprotrophic organisms are not classed as detritivores because they (saprotrophs) digest material differently - they complete extracellular digestion whereby enzymes are secreted onto the material outside the body, the products are then absorbed. Detritivores are animals such as earthworms or millipedes - they consume the organic matter and break it down using a specialised digestive system.
c) The minerals cycle is between the abiotic factors of an ecosystem and the biotic factors of an ecosystem.
a) The CARBON CYCLE. Carbon is a major component of all organic molecules, including carbohydrates, fats and proteins! During the day plant photosynthesis converts CO2 from the air into carbohydrates (glucose for example). What 2 human activities have been the main cause of this rise?
b) The carbon cycle involves 3 major biological processes. Name each… + explain each of the 3…
a) 1. Burning fossil fuels releases CO2 that was previously ‘locked’ up in them, into the atmosphere.
2. Deforestation has removed large quantities of photosynthesising biomass and so less CO2 is being removed from the atmosphere as a result of this
b) 1. Respiration = CO2 is added to the air by the resp. of animals, plants and microorganisms.
2. Photosynthesis = CO2 is drawn in.
3. Decomposition = The production of carbohydrates, proteins and fats contribute to plant growth and subsequently to animal growth through complex food webs! The dead remains of plants and animals are then acted upon by detritivores and saprotrophic organisms who are in the SOIL. This ultimately releases CO2 into the atmosphere.
The cycle continues!
a) In aquatic ecosystems things are different! How does CO2 exist in aquatic environments?
a) IN aquatic organisms, CO2 exists as hydrogencarbonate ions (HCO3-). HCO3- undergoes the same processes as described for terrestrial organisms (remember that terrestrial organisms are those who exist on land).
a) Now we shall assess the human impact on the carbon cycle. Firstly, DEFORESTATION.
Deforestation does WHAT to the CO2 content in the atmosphere? There are 2 forms that cause the problem regarding deforestation. Explain them. Both contribute to climate change!
a) Deforestation INCREASES the CO2 content in the atmosphere. This is because the rate at which CO2 is REMOVED from the atmosphere is reduced by cutting down forests. Remember that CO2 is drawn in for photosynthesis. Less trees means less photosynthesis is occuring which in turn means less CO2 is being used up! Additionally, when trees are burnt or left to decay, they release CO2 back into the atmosphere!
a) Now we shall look at the ‘greenhouse effect’. Why are gases like CO2 called ‘greenhouse gases’? They act like WHAT that traps heat in a greenhouse? List the 6 greenhouse gases…
b) Describe how solar radiation reaches the Earth and how some of it is absorbed and re-radiated to the Earth. Is this all normal - i.e. is this a natural process?
c) Explain what is meant by the ‘enhanced greenhouse effect’.
a) Greenhouse gases in the atmosphere are called this for a reason! This is because they are said to behave like the GLASS in greenhouses. Greenhouse gases include: CO2, CH3 (which has a global warming factor 20x larger than CO2), nitrous oxide, CFCs, ozone layer and water vapour.
b) These gases (CO2, CH3, CFCs, Ozone Layer, Water Vapour & nitrous oxide) allow high-energy, short wavelength solar radiation to enter the Earth’s atmosphere. This radiation has been emitted by the SUN. Much of the high-energy, short wavelength radiation is absorbed by the EARTH itself. This warms up and re-radiates lower energy, LONGER wavelength infra-red radiation. This reaches the outer atmosphere where the wavelengths are ABSORBED by the gases that exist in that region (the greenhouse gases we’ve touched on). These gases then re-radiate them back to the Earth surface which absorbs it all.
Key to remember that all of this is a natural process and without this the Earth wouldn’t be habitable due to the cold temperatures!
c) The ENHANCED greenhouse effect caused by high concentrations of greenhouse gases is called global warming. SO remember this - that it’s due to the HIGH CONC. that’s present in the atmosphere!
a) We are still on ‘global warming’ but we will now look at the list of consequences of global warming. Provide a list and short explanation for the consequences of global warming! There are 9 parts.
a)
1. The polar ice caps melt as a result. This causes flooding of coastal areas.
- Extreme weather conditions - including droughts, hurricanes and cyclones (they all become more FREQUENT).
- Fires are more frequent and are more INTENSE
- Ocean pH. has decreased (i.e. become more acidic) as MORE CO2 dissolves! Remember that hydrogen carbonate ions are acidic - protons are released! This threatens many organisms: fish secrete mucus, protecting their gills but as a result they can’t perform GAS EXCHANGE. Furthermore, the external skeleton of corals is largely calcium carbonate which dissolves in acid!
- As ocean temp. rises, corals lose their colour and they expel algae. This destroys the coral reefs.
- Water availability decreases in tropical areas, leading to the formation and expansion of deserts!
- Evolutionary adaption is slow so, as the climate changes, animals move to more suitable environments. Plants can only move as fast as they are dispersed, and if this is NOT fast enough (i.e the dispersal), they are at risk of extiction. This is NOT good - REMEMBER we animals are dependent on plants which means we too shall eventually become extinct including other animals causing the entire ecosystem to collapse.
- Pests and pathogens may alter their distribution, comprimising the health of plants including crops, humans and animals in general. Concern over northernly spread of mosquitos (who are vectors for diseases such as malaria).
- Crop yields may rise in warmer temperatures allowing more photosynthesis, but extremly high temps, can cause a reduction in crop growth.
a) We shall now look at how humans have caused global warming to impact farming. Agriculture is VERY vunerable to the impacts of climate change and is likely to be affected through changes in __________ and timing and quantitiy of ____. As gloabl warming increases, events, such as droughts and floods, are likely to be more frequent.
a) Agriculture is VERY vunerable to the impacts of climate change and is likely to be affected through changes in temperature and timing and quantity of RAIN.
a) What is the meaning of ‘carbon-footprint’?
a) Carbon footprint - This is the equivalent amount of carbon dioxide generated by an individual, a product or a service in a year. It’s a way of measuring an individual’s contribution to greenhouse gases in the atmosphere.
The NITROGEN cycle.
a) What is the nitrogen cycle? It’s the flow of nitrogen atoms betweenn ______ and ______ nitrogen compounds and atmospheric nitrogen gas in the ecosystem.
b) Living organisms NEED nitrogen in order to do WHAT key thing?
c) Can plants and animal use nitrogen gas?
d) How do plants obtain nitrogen? Formula for a nitrate ion?
e) How is nitrogen passed along the foodchain?
f) How do materials/minerals get returned to the soil? Which organisms are involved in the nitrogen cycle?
The decomposition of plants and animals after their death and of excreted and egested products of animals, releases the minerals BACK into the soil. Bacteria are the key organisms involved in the process of the nitrogen cycle!
DRAW THE CYCLE OUT
a) The nitrogen cycle is the FLOW of nitrogen atoms between organic and inorganic nitrogen compounds and atmospheric nitrogen gas in the ecosystem.
b) They require nitrogen in order to make amino acids (remeber that nitrogen is a key constituent in amino acids!). This allows them to from proteins as a result!
c) NO they cannot use nitrogen in its gaseous state.
d) Plants absorb nitrates thorugh their roots from the soil. Nitrate ion = NO3-
e) Organic nitrogen compounds (e.g amino acids) produced by plants are consumed by primary consumers.
f) The decomposition of plants and animals after their death and of excreted and egested products of animals, releases the minerals BACK into the soil. Bacteria are the key organisms involved in the process of the nitrogen cycle!
We shall now progress onto the HUMAN impact on the nitrogen cycle.
a) What have humans done thus far to crops to meet increasing demand? There are 3 things. Why is it critical that these things are done - think about the population…
b) Human activities can improve the circulation of nitrogen in agricultural soils. We shall go through the various methods. Ploughing fields can improve the circulation of WHAT in agricultural soils (not oxygen). Aerobic organisms, such as free-living nitrogen fixers, enhancing the formation of __________ ____ in the soil. Thus, the formation of nitrites and nitrates is enhanced!
c) Draining the land allows air to enter the soil and so it ________ the _________ CONDITIONS that we DO NOT want (because NO3- turns into N2 due to ______________ operating bacteria like __________ - a denitrifying bacteria). In this way the loss of nitrates is REDUCED.
d) The Harber process converts large amounts of nitrogen into ammonia, WHY? Think about food quality. What are fertilisers?
Artificial nitrogen fixation (e.g. the Harber process converts nitrogen to ammonia, used to make fertilisers, essentially to produce high volumes of good quality food). Fertilisers are largely compounds containing ammonium and/or nitrate ions (ammonium nitrate, and augment the ammonium ions and nitrates produced by nitrogen fixing and nitrifying bacteria, respectively.
a) As the human population increases, there is need to produce INCREASING amounts of food. Plant breeding and genetic modifications make a CONTRIBUTION to this goal, as does the usage of various pestisides. Treating soil and maintaining its structure are also vital for efficient food use of production.
b) Ploughing fields can improve the circulation of NITROGEN in agricultural soils because aerobic organisms such as azobacter enhance the formation of ammonium ions in the soil. They possess the required enzymes to break the N to N triple bond.
c) Draining the land allows air to enter the soil and so it reduces the anerobic CONDITIONS that we DO NOT want (because NO3- turns into N2 due to anaerobically operating bacteria like pseudomonas - a denitrifying bacteria).
d) Artificial nitrogen fixation (e.g. the Harber process converts nitrogen to ammonia, used to make fertilisers, essentially to produce high volumes of good quality food).
Fertilisers are largely compounds containing ammonium and/or nitrate ions (ammonium nitrate, and they (fertilisers) augment the ammonium ions and nitrates produced by nitrogen fixing and nitrifying bacteria, respectively).
Continuing…
a) Large amounts of animal waste are used as ‘brown’ manure, why? What does it do to the soil? What does the manure contain that gets returned to the soils and is good for plant growth…? This improves the soil’s WHAT because of it having more nutrients and water…? This is turn promotes WHAT activity which in turn promotes the mineral supply of the soil?
b)
a) Large amounts of animal waste are used as ‘brown’ manure. The nitrogen and other nutrients the manure contains are essentially growth for the plants. It IMPROVES the soil’s tructure in terms of the soil holding more water and nutrients making it more fertile as a result! This promotes microbial activity, which in turn promotes the mineral supply of the soil!
b)
a) There are 4 main biological processes in the nitrogen cycle. List the 4 out.
a) 1. Ammonification
2. Nitrification
3. Denitrification
4. Nitrogen fixation
a) What is ‘ammonification’? What do detritivores do as well as saprobionts?
b) What do proteases do?
c) What do deaminases do?
a) Ammonification is the processin which ammonium ions are fixed into the soil. Detritivores CONSUME dead organisms and waste products produced by organisms in general. Saprobionts (organisms that complete extracellular digestion in which enymes are secreted onto the material to digest it) such as fungi & bacteria, collectievly called decomposers are also involved too.
b) Proteases break down proteins into their individual amino acid constituents.
c) The broken down amino acids are then handled by deaminase enxymes which remove the N-termianl from the amino acid (the NH2 group).
a) What is ‘nitrification’? The ammonium ions formed from WHAT are converted in the process of ‘nitrification’. What bacterias are involved (give their position in the nitrifiaction process starting from ammonium ions)…? What type of reaction is this?
a) Nitrification is the addition of nitrogen to the soil in the form of nitrites or nitrates. The ammonium ions formed during decomposition are converted, in a process called nitrification. Nitrification is an oxidation reaction.
Nitrosomonas converts ammonium ions into nitrites. Nitrites are converted into nitrates by the bacteria, nitrobacter.
b) In anaerobic conditions the bacteria pseudomonas converts nitrates into N2 molecules which is the process of DEnitrification - i.e. the loss of nitrates from the soil. This is a reduction reaction.
a) WHAT is nitrogen fixation?
b) Why can’t majority of organisms not convert nitrogen themselves directly from the atmosphere?
c) Why can’t plants rely on geological processes to release ammonium ions and nitrates?
a) This is the reduction of nitrogen atoms in nitrogen molecules (N2 molecules) to ammonium ions by prokaryotic organisms (who contain the enzyme required to break the n to n triple bond).
b) Although 79% of the atmosphere contains nitrogen, only a handful of organisms can actually convert it into the desired format. This is because majority of organisms lack the possession of the enzyme needed to break the n to n triple bond.
c) Because these processes are lenghty - they’re SLOW.
a) What bacteria accounts for majority of the biological nitrogen fixation?
b) There are some bacteria who form a WHAT relationship with several angiosperm families. One of them is the bacteria called, WHAT? This bacteria is found in the WHAT of the root of plants found in the WHAT family - LEGUMES.
c) Oxidising conditions impact the rhizobium. WHY? N2 gas goes into the legume root nodule HOW? What colour is the colour of the nodule if leg-haemoglobin is found?
d) What happens to the ammonium ions formed?
a) Azotobacter is a free-living nitrogen-fixing bacterium in the soil and it accounts for most biological nitrogen fixation.
b) There are some bacteria who form a symbiotic relationship with several angiosperm families. One of them is the bacteria called, rhizobium. Rhizobium is found in the root NODULE of plants found in the fabaceae family - LEGUMES
c) Nitrogen gas diffuses into the legume root nodule from the atmosphere and the nitrogenases catalyse the convertion (the rhizobium bacteria possesses). Nitrogen fixation is a reduction reaction, and is poisoned by oxidising conditions. Genes of the host plant code for a type of haemoglobin called leg-haemoglobin which binds oxygen in the nodules protecting the reactions from oxidation as a result.
d)The ammonium ions formed are converted into organic amino acids and then into amino acids.
a) Now, it must be known that the radicle of a legume plant does NOT initially contian the rhizobium bacteria. Describe the process in which both parties meet. How do the nodules then form?
a) The radicle and rhizobum BOTH release chemoattractants. The radicle growns towards the rhizobium cells and the rhizobium cells use their flagella to move towards the radicle. The rhizobium cells invade the CORTEX and the large number produced (rhizobium) from their replication causes root nodules to form.
Human impact on nitrogen-cycle:
a) Slurry is a liquid made from _____ and _____. It’s produced by more intensive livestock-rearing systems, where concrete or slats are used, instead of straw bedding. It is usually stored in a tank or lagoon before usage. How are they applied to soils? Thin about the smell they emit and how this may factor into the choice of method in which the slurry is applied to the soil through spreading on the surface of the soil…
Planting fields of legumes enhances nitrogen fixation. When they die, they’re ploughed back into the soil to make the soil structure more nitrogen rich!
a) Slurry is a liquid made from manure and water. It’s produced by more intensive livestock-rearing systems, where concrete or slats are used, instead of straw bedding. It is usally stored in large tank or lagoons before it’s used.
Slurry is NOT applied to the soil by just spreading it over the soil - this is because of the smell slurry emits. Instead it’s injected into the soil.
Effects of fertilisers on habitats:
a) Upland streams are oligotropic. What does this mean? As water flows over rocks, it dissolves minerals and their concentration increases (mineral concentration). Water enriched with minerals is described as WHAT? When mineral concentration is so high that organisms die, the water is described as WHAT?
b) What is EUTROPHICATION?
a) This means that they have very FEW minerals dissolved in them. As water flows over rocks, it dissolves minerals and their concentration increases (mineral concentration). Water enriched with minerals is described as EUTROPHIC. When the mineral concentration is so high that organisms die, the water is best described as dystrophic.
b) Eutrophication is the process of of ARTIFICALLY increasing the mineral content of the water as a result fo nitrogen containing fertiliser that have leached from agricutrual land nearby…
Nitrate is highly soluble and is readily leached from soil and washed into rivers from surrounding land.
Nitrate can drain through the soil under the pull of gravity causing it to meet with ground water!
Nitrate is a fertilisers and algae respond so the first effect may be an algal BLOOM. The water becomes GREEN as a result of this, and light is unable to penetrate to any depth!
The plants in the deeper regions of the lake cannot photosynthesise effectively and the they die as a result!
The diversity in general of animal species decreases because they rely on plants for food and shelter!
The short lived algae soon die however… They decompose by saprobiontic bacteria and fungi. These are aerobic organisms and therefore use a lot of oxygen creating a biochemical oxygen demand (BOD).
The upper layers of the water that are exposed to the air become DEOXYGENATED causing the death of the surrounding fish population etc…
