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Description
Flashcards by Darcey Griffiths, updated 29 days ago
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Created by Darcey Griffiths
3 months ago
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| Question | Answer |
| Ecology definition | The study of living things and their interactions with each other and their environment. |
| Population definition | An interbreeding group of organisms of the same species occupying a particular habitat |
| Ecosystems definition | A characteristic community of interdependent species interacting with the abiotic components of their habitat. |
| Birth rate definition | The reproductive capacity of a population; the number of new individuals derived from reproduction per unit time |
| Population definition | All the members of one species in an area that can breed with each other. |
| Community definition | All the members of all species in an area. |
| Habitat definition | The place in an ecosystem where an organism lives. |
| Immigration definition | The movement of individuals into a population of the same species |
| Equilibrium species definition | Species that control their population by competition rather than by reproduction and dispersal |
| Ecosystem changes | An ecosystem is not a static component; things change all the time. The source of energy for ecosystems is the sun. In temperate climates, the duration and intensity of sunlight changes over the course of a year, so the energy that flows through the ecosystem is subject to change. |
| Ecosystem changes pt 2 | Nutrient cycles depend on fungi and bacteria, and their population growth is dependent on temperature (amongst other abiotic and biotic factors), so nutrient cycling varies throughout the year- ( cyclic pathway by which nutrients pass-through, in order to be recycled and reutilised. The pathway comprises cells, organisms, community and ecosystem.) |
| Factors controlling population size | Intensity of energy flowing through an ecosystem varies Biological cycles eg nitrogen cycle vary the mineral availability Habitats change over time as succession occurs New species arrive and some are no longer present Climate change alters habitats |
| Ecosystem changes pt 3 population | Community composition can change over time, for example, ponds silt up and land plants become established, this is known as succession. Population sizes change over time. |
| Things affecting population size | The population size is dependent on 4 factors – the reproduction rate, the death rate, immigration and emigration. In a stable population these are balanced and can be expressed as an equation: Reproduction + immigration = death + emigration This is because reproduction and immigration increase the size and death and emigration decrease the size of the population. |
| What determines population size | Birth rate, Immigration= increase pop Death rate or mortality,Emigration= decrease pop When combined effects of birth and immigration exceed death and emigration pop increases |
| Population size- fugitive/ equilibrium | Different strategies for population growth are used by different species, depending on characteristics- there's fugitive and equilibrium species |
| Fugitive | Fugitive species are poor at competition- instead rely on large capacity for reproduction/ dispersal to increase numbers- invade a new environment rapidly |
| Equilibrium species | Control population by competition in a stable habitat- usual pattern of growth is sigmoid- s shaped- curve called one step growth curve |
| Diagram of pop growth | p64 |
| Niche definition | The role of an organism in an ecosystem, generally a feeding role. |
| Biotic | All the living and organic components of an ecosystem. |
| Abiotic | All the non-living parts of an ecosystem. |
| Population size- lag phase | Initially pop doesn't increase - period of slow growth- period of adaptation/ preparation for growth- rehydration and intense metabollic activity, especially enzyme synthesis- in sexually reproducing organisms- lag phase represents time for individuals o reach sexual maturity, find a mate and gestate young |
| Growth curve- what is it | Populations colonizing new environments undergo a characteristic series of stages that can be presented graphically as a growth curve. When writing about animals we tend to use the term birth rate rather than reproduction – careful not to use this for bacteria or fungi. |
| One step growth curve- bacteria | Bacteria in a nutrient broth first go through a lag phase. They are synthesising enzymes and replicating DNA. The numbers of individuals rise slowly. As food availability is high, the growth becomes exponential. Therefore, the cells divide rapidly, reproduction exceeds death rate and the population doubles for each unit of time. This is the log phase.As nutrients start to run out or get depleted, the reproduction and deaths in the population stabilise, this is the stationary phase. Death and reproduction are equal.Eventually the toxins in the broth build up to such an extent that deaths exceed reproduction and the population decreases in the death phase. Death could also be caused by nutrients running out in the broth. |
| But... | However, in less artificial situations other factors play a part- same factors apply but are additional biotic factors eg predation, parasitism/ disease as increased pop density allows infection to spread more rapidly, competition w/ other species for nesting sites and food- also abiotic factors eg temperature, light intensity (eg plants). |
| One step growth curve- animals- lag/ log phase | The lag phase is when the animal first arrives in an area, e.g. when grey squirrels were first introduced to Britain. The population increases slowly at first, there are not many individuals to breed and time is needed for enough individuals to reach sexual maturity. Log/ exponential phase- With plenty of food, the population increases exponentially. |
| One step growth curve- animals-stationary phase | Competition for food, territory and habitats is low; this is the log phase. Eventually the population reaches a maximum, called the carrying capacity- this number depends on resources available eg more food increased carrying capacity- pop= not absolutely constant fluctuates around cc in response to environmental changes |
| One step growth curve- animals-death phase | The factors that slow pop growth at end of log phase become more significant- pop size decreases until death rate is greater than birth rate- graph has negative gradient |
| Environmental resistance and carrying capacity | Predators= usually larger than prey and tend to kill before eating- abundance of prey limits no. predators and no. predators affects no. prey- predator-prey relationship causes both populations to oscillate (back and forth)-- oscillations limited by negative feedback (the effect that change in one part of an ecosystem or social system has on the very same part after passing through a chain of effects in other parts of the system)- |
| Negative feedback example | eg predators cause no. prey to decrease--- lack of prey- predators decrease--- lack of predators prey increases--- more prey predators increase- population numbers at carrying capacity can depend on numbers in other species |
| Calculating pop increase from a graph | When pop increase is very large- eg pop of bacteria in test tube- range of numbers is too great to plot on a linear scale- A log 10 scale is therefore used- each mark on pop size is ten times previous mark- shift log to see what population actually is- growth rate- no. species at certain time- no.species at another time (pop growth)/ time- no.species at both times antilogged to get proper amount |
| other calculations | for less than 1000 in pop: Birth rate: increase in pop/ original pop - to get to percentage- divide to 100- same structure for death rate over 1000- (Number of live births / Total population) * 1,000- will give you per 1000- eg if 4000- times no. by 4 net migration rate-: N = (I - E) / M X 1,000 N = Net migration rate I = Number of immigrants entering the area E = Number of emigrants leaving the area M = Mid-year population |
| Factors that regulate population increase- density dependent | Some environmental factors have more effect on given population if given area is larger- factors affect greater amount of population if pop is denser- called density dependent factors- biotic factors- include disease, parasitism and depletion of food supply |
| Factors that regulate population increase- density independent | Effect of abiotic factors in environment does not depend on population density- effect is same regardless of size of population- usually due to a sudden change in an abiotic factor eg flood/ fire |
| Populations fluctuate in numbers | Balance between birth rate and death rate regulates the size of a population- doesn't stay stay constant- in equilibrium species - usually fluctuations aren't large or erratic- numbers in populations fluctuate around a set point- if population rises above set point density dependent factor increases mortality or reduces breeding to extent that pop declines If pop falls below set pointr- environmental resistance is relieved for a bit- pop rises again |
| look at diagram for negative feedback | p69 lol |
| Abundance and distribution of organisms in a habitat | The study of species abundance and distribution= biogeography- Alfred R Wallace was first to model biogeographic regions- defined 6- when studying birds and other vertebrates- saw mountain ranges marked boundaries of many species' ranges and saw different animals in similar habitats- didn't correspond with prevailing exp that all organisms were created to suit particular environment |
| New habitat | When new habitat is assessed- physical features eg soil type and temp are described first- determine no./ type of plants that live there- also dependent on weather that usually occurs- animals in a habitat depend on plants- so in new habitat- plants described before animals |
| Measuring abundance | Abundance- no. individuals in a species in a given area or volume- can be assessed by: capture, mark, release, kick sampling in a stream and counting aquatic invertebrates |
| Measuring abundance plant species | Using quadrat to calculate the mean number of individuals in several quadrats of known area to find the density eg no./metre^2 Estimating % cover of a plant in which individuals are hard to recognise- estimating % frequency |
| Measuring distribution | Distribution- the area or volume in which an organism is found If habitat is uniform- (organisms are spread out in a fairly regular pattern)- positions of outermost plants= marked on map and area they surround can be measured- small area may indicate species is under threat of extinction- used to assess distribution of threatened plant species- mining companies and road building authorities can be lobbied to protect specific sites |
| measuring distribution pt 2 | If habitat is non uniform- transect is useful for displaying variation in organisms and its correlation with a changing abiotic factor- a transect is line along which abundance is assessed- shows the organisms that lie on a line, at measured intervals A belt transect shows abundance data for given area at measured distances along transect- quadrat placed at each co-ordinate can show- density of chosen species, % frequency of chosen species, % area cover for all species |
| Kite diagram | shows % area cover for species across belt transect- to draw- draw x axis for length and y axis for 5 cover with 50% above and below x axis At each co-ordinate- place data points above and below x axis- each representing half of the % area cover join last two data points with a vertical line join data points above and below the axis |
| Ecosystems | Ecosystem= A characteristic community of independent species interacting with abiotic components of their habitat Community is many specie living and interacting together- interactions of organisms together and non living factors in their environment= ecosystem- biotic and abiotic factors are linked by energy flow and cycling of nutrients |
| Ecosystems can be... | Small- eg human large intestine and community of microorganisms Very large- Seas- some consider earth to be one large ecosystem Temporary- puddle left after rain Lasts millions of years- |
| Ecosystem examples | Ecosystem- Marine Example- Pacific ocean Abiotic features- aquatic- high mineral ion concentration Characteristic organisms- fish, algae,echinoderms Ecosystem- Artic Tundra Example-Canada, Siberia Abiotic features- temp change between -50C and +12C, 15-25 cm rainfall a year, windy Characteristic organisms- low growing plants, reindeer, arctic hare |
| Energy and ecosystems | Energy= no changes happen until energy changes occur- functionings of an ecosystem can be thought as a sequence of energy changes in which energy flows through components of an ecosystem Subject to certain rules- described as laws as thermodynamics |
| Energy and ecosystems pt2 | Many possible energy sources on earth eg geothermal, electrical and chemical Been suggested: energy derived from unequal distributionof protons allowed the non living systems in the cavities of alkaline hydrothermal vents to make the transition into living systems early organisms used energy released by chem reactions to make carbohydrates by chemosynthesis... |
| Continuation of theory | ...The electrons they need to reduce CO2 or methane to sugar are from the oxidation of inorganic molecules eg hydrogen or hydrogen sulphide. Some archea and bacteria still do- but tend to inhabit marginal ecosystems most significant energy source for ecosystems now is light energy radiation from the sun - light energy source for photosynthesis |
| Biotic components of an ecosystem- habitats | A habitat= The place in which an organism lives ecological or environmental area inhabited by a living organism- provides means of survival- food, water, soil, appropriate temp/ PH Not necessarily geographical area- part of 1 organism may be habitat for another eg human duodenum for tapeworms Microhabitat= very small area- differs from its surroundings has the features make it suitable for specific species |
| Biotic components of an ecosystem- Communities | Communities= Interacting populations of 2 or more species in the same habitat at the time -members of a species living and interacting in a habitat forms population- populations interact to form community- |
| Community ecology | community ecology studies interactions of the species related to distribution and abundance and their genotypic and phenotypic differences. Considers food web structure/ predator-prey relationships |
| Biotic components of an ecosystem- biomass transfer | Biomass- The mass of biological material in living or recently living organisms Ultimate source of energy for most ecosystems= sunlight- photosynthetic organisms convert light energy into chemical energy- passes from organism to another through food chain- the study of the flow energy through ecosystem= ecological energetics- energy available to a trophic level contributes to its biomass- Food chains can be thought as transferring biomass |
| Food chains | Producers- green plants, cyanobacteria, some Protoctista- incorporate suns energy into carbohydrates- this is food and so energy source for successive organisms in food chain- trap solar energy and synthesize sugars from inorganic compounds by photosynthesis- |
| Why does only small proportion of energy reach plant as light is incorporated into plants tissues | h |
| Food chains pt2 | herbivores= primary consumers- carnivores= secondary/ tertiary and higher consumers Each of these groups operates at a feeding or trophic level with energy passing to a higher as material is eaten Energy in the food consumed is incorporatedinto molecules of the consumer As energy is passed along the food chainthere's a loss from the food chain at each level- energy flowing through ecosystem reduces- ultimately energy leaves system as heat |
| Decomposition | When producers/ consumers die- energy remains in organic compounds of which they are made- detritivores and decomposers feed as saprobionts- derive energy from dead/ decaying organisms- contribute to recycling of nutrients- |
| Difference- detritivores and decomposers | Detritivores- organisms eg earthworms, woodlice and millipedes- feed on small fragments of organic debris- this is detritus= the remains of dead organisms/ fallen leaves Decomposers - micrrobes such as bacteria and fungi that obtain nutrients from dead organisms and animal waste- complete the process of decomposition stated by detritivores. |
| Food web chains and their length | Food web shows how organisms in a community interact through food they eat-food chain is linear sequence of organisms in a food web producer (1st trophic level)---> primary consumer (2nd trophic)--->secondary consumer (3rd trophic)---> tertiary consumer (4th trophic) |
| Food chain pt 2 | Energy lost at each link along food chain- after 4 or 5 levels not enough energy to support another one - no. links in a chain= limited Actual length depends on interacting factors: - More energy that enters food chain in first trophic level- eg more energy fixed in photosynthesis- longer food chain is-tropical food chains usually longer than arctic ones How efficiently energy is transferred between trophic levels Predator and prey populations fluctuate- affects chain length How large ecosystems is 3 dimensional environments eg aquatic systems have longer food chains than 2 dimensional habitats eg grasslands |
| look at diagram photosynthetice efficiency | p74 |
| Photosynthetic efficiency- maths | Energy flowing from 1 organism to another- in food chain originatees as sunlight- about 60% of light energy that falls on plant may not be absorbed by photosynthetic pigments- could be; wrong wavelength, reflected, transmitted straight through leaf Photosynthetic efficiency= ability of plant to trap light energy PE= (quantity of light energy incorporated into product/ quantity of energy falling on plant ) x 100 wild plants may be low but higher in crop plants - selectively bred for high productivity- PE depends on plants genotype/ environmental factors |
| Primary productivity | Gross Primary productivity- rate of production of chemical energy in organic molecules by photosynthesis in given area, in a given time- kJ m-2y-1 A substantial proportion of gross production= released by respiration of the plant to fuel processes eg protein synthesis Remains= net primary productivity- represents energy in plants biomass= food available to primary consumers or in crops= yeild that can be harvested |
| Primary productivity pt 2 | equation: GPP-respiration= NPP Both GPP and NPP are higher if plants have high PE - unlike crop plants- many plants less productive and not grown in deal conditions- so common figure for GPP is around 0.2- 2% of incident radiation and 0.1-1% for NPP |
| Energy flow through food chains | Primary productivity= rate at which producers convert energy into biomass- secondary productivity is rate at which consumers accumulate energy from assimilated food in biomass in their cells or tissues- secondary production occurs in heterotrophs eg animals, fungi, some bacteria, some protoctista |
| Why is energy lost along food chain | - energy molecules egested- eg cellulose not digested in cows gets excreted- however energy not lost from ecosystem- used by decomposers- carnivore's diet more digested- less energy lost -energy lost as heat following processes fuelled by the energy generated in respiration including muscle contraction - energy remains in molecules in parts of an animal that may not be eaten eg horns, fur and bones |
| Herbivores vs carnivores | herbivores- conversion efficiency of around 10% so only 10% of of plant material digested is incorporated into their biomass- so only part of NPP of whole ecosystem is transferred to primary consumers- also herbivores won't eat all vegetation available to them when grazing- carnivores are more efficient at energy conservation- foodeasily digestedmore easily |
| Fate of energy in consumers | Heat loss from reactions of respiration- P= 30% (ingested energy in consumer), S=60% In excreted and egested waste products-P= 60%, S= 20% Secondary production= P=10%, S=20% |
| Calculating efficiency of enregy transfer | efficiency of energy transfer: (energy incorporated into biomass after transfer/ energy available in biomass before transfer) x 100% eg 1609 kjm-2 in primary consumers ingessted by secondary- 193 kjm-2 transferred to detritivores and 88 kjm-2 transferred to tertiary (88+193/1609)x 100% |
| Ecological pyramids | Ecological pyramid is a diagram that shows a particular feature of each trophic level in an ecosystem- producers are drawn at bottom and succesive trophic levels are above- no. organisms, energy or biomass at each trophic level is represented by bar for each level- known as pryramids of numbers, energy or biomass depending on what's show |
| Ecologocal pyramids- pros and cons | Useful in describing ecosystems + Do not take account of fact some organisms operate at more than one trophic level at same time- eg human is omnivore can eat producers eg plant- primary or secondary eg eating egg from chicken look at diagrams p77 |
| Pyramid of numbers pros and cons | - relatively easy to construct + does not take into account actual size of organisms range of no.s may be so large may be difficult to draw scale pyramid may be inverted if 1 trophic level has more organisms than previous trophic level look at diagram p78 |
| Pyramid of energy | Most accurate way of representing feeding relationships- shows energy transferred from one trophic level to next per unit area or volume, per unit time as you go through food chain- energy lost from ecosystem- so area of bars decreases accordingly energy pyramids never inverted- easy to compare efficiency of energy transfer between trophic levels in different communities |
| Pyramid of biomass pt 1 | Energy = incorporated into macromolecules that make up biomass of an organism- if available energy is greater, more biomass can be supported- so pyramid of biomass is closely related to energy passing through an ecosystem |
| pyramid of biomass judgement | Pyramids of biomass effectively represent energy flow through an ecosystem Difficult to measure accurately eg all plant's roots must be included Don't indicate productivity or amount of energy flowing through ecosystem pyramids may be inverted |
| pyramid of biomass judgement pt 2 | trophic level may seem to contribute more to next trophic level than it actually does as organisms contain structures with mass that will not transfer to next trophic level eg bones/ beaks Species with similar biomass may have different lifespans- direct comparison of total biomass is therefore misleading |
| Inverted pyramid of biomass | In aquatic ecosystem phytoplankton= major producers- lots of energy flows through first trophic level and phytoplankton reproduce very quickly- some are eaten immediately- leaving just enough to maintain pop so their standing crop eg mass of individuals present at given time is lower than biomass of zooplankton which eat them- look at diagram- 78 |
| Community and Succession | Ecosystems are dynamic (constantly changing)- organisms and their environment interacts- so change in environment affects organisms- change in community structure/ species over time= succession- can be over short time eg after natural disaster or over millions of years eg after mass extinction- new species invade- replace existing ones- until a stable community (climax community) is established |
| Succession- general definition | The change in structure and species composition of a community over time- A process by which communities of plants and animals colonise an area and then, over time, are replaced by other, more varied organisms. |
| Primary succession/ climax community | WJEC Definition- The change in structure and species- composition of a community over time in an area that has not previously been compromised- sequence of changes after a new species enters an area that has not previously supported the community- a stable, self perpetuating community that has reached equilibrium with its environment- no further change occurs |
| Primary succession and seral stages | Primary succession changes following introduction of species to an area which has never had a community eg bare rock- sequence of communities with different species and structure= sere- so overall series of changes that happen to community- primary succession is type of sere- seral stages is certain points of development in sere- like snapshot of how community is at different points of development |
| Primary succession stage 1- pioneer species | The first species to colonise a new area in an ecological succession- able to withstand desiccation/ extreme temps and low levels of nutrients- The first species to colonise the new land, often mosses and lichens- wjec states lichens break down rock first and wind blown spores/ seeds cause mosses to grow directly after- Pioneer species can germinate easily- little needs- animals eg ants mites and spiders can survive when there's enough food for them |
| Primary succession stage pt2 | The pioneer species penetrate and break up the rock As the pioneer species die and decompose, primitive soil builds up. |
| Primary succession stage- pt 3 | - wind blown spores- mosses can grow The plants at this early stage of succession are adapted to survive in shallow, nutrient-poor soils. As soil develops grasses and small herbacious plants outcompete mosses become established- dispersed species that make a lot of seed and germinate in direct sunlight are favoured. Mosses and ferns cast shade to stop further growth of lichens.- animals eg nematodes, ants, spiders and mites can survive. |
| Primary succession- stage 4 | Growth of larger plants and the animals which inhabit them will cause further changes in soil and light conditions. Tall grasses allow shade tolerant species to become established- community becomes more complex. |
| Primary succession- stage 5 | As plants and animals die and decay- soil becomes thicker- more minerals- more humus- (the organic component of soil, formed by the decomposition of leaves and other plant material by soil microorganisms.)- soil holds water more efficiently- soil builds deeper rooted plants eg shrubs and small trees outcompete herbaceous plants |
| Primary succession pt 6 | Soil continues to deepen and increase in minerals/ humus- over long time- large trees outcompete shrubs and small trees become well established- grows to form climax community- great species diversity- complex food web- dominated by long lived plants |
| Climatic climax community | Species of climax community can depend on climate- so climax community is also called climatic climax community- animal species is at highest eg invertibrates- slugs, snails, worms and vertebrates- squirrels, foxes , birds, salamanders, frogs but tree canopy limits intensity reaching floor- plant diversity decreases slightly from pre- climax state |
| The climax community is balanced with... | GPP- gross primary productivity and total respiration Energy used from sunlight and released by decomposition Uptake of nutrients from soil/ their return of nutrients by decayed plant/ animal remains New growth and decomposition so quantity of humus is constant |
| Xerosere | sere in very dry environment= xerosere- as xerosere progresses increases are seen in soil thickness and availability of water, humus and minerals biomass biodiversity resistance to invasion of new species stability to disruption by environmental changes |
| Secondary succession | recolonisation of a habitat previously occupied by community but disturbed eg fire/ tree falling- area rapidly gets re-colonised by succession- actual species depends on conditions prior to disturbance eg soil thickness, minerals and humus content- example- seeds, spores and organs of vegitative reproduction (bulbs) may remain in soil and dispersal of plants/ migration of animals will help in recolonisation |
| primary and secondary compare | As soil is already fertile secondary succession will have same sequence as primary succession but a lot faster- more commonly observed and studied due to this- species that grow rabidly= often grasses, other herbaceous plants eg heathers, ferns, birch trees and branches |
| Disclimax | Human interference can affect a succession- may prevent development of climactic climax community- eg shepp grazing- grassland suffers- prevent shrubs and trees from growing farming- removes all except deliberately introduced species Deforestation- removes community of large trees- smaller trees may be replanted. |
| Sometimes disclimax can be good for other species | eg grouse only feed on young shoots- burning can be carried out in some circumstances- pioneer phase is best for giving food and building phase is best for giving shelter/ nesting |
| Factors affecting succession | Immigration- arrival of spores, seeds and animals= vital for succession Competition- all communities- organisms compete for survival- plants compete for light, space water and nutrients, animals compete for food, shelter, space and reproductive partners |
| Types of competition/ how does it affect succession | Intra specific- between individuals of same species- density dependent- as population increases= more competition- so denser population=greater amount of population fails to survive- of value species tend to produce more offspring than necessary- organisms with allelles best suited to environment- better survival |
| Types of competition/ how does it affect succession pt 2 | Inter specific- competition between those of different species- different species- have common needs- but each has its own niche in an ecosystem-role and position species has in environment including interaction with the biotic and abiotic factors of its environment- competition is at all seral stages- in long term 2 species cannot occupy same niche in specific habitat- survival of fittest |
| Gause | Russian scientist- cultured 2 species of paramecium with yeast as food source- grown separately in identical conditions- P. aurelia and P. caudatum both showed 1 step typical growth curves yet when grown together- slower growing P.C died- helped Gause form 'competitive exclusion principle- 2 species can't occupy same niche |
| Facillitation | Association between individuals of different species=symbiosis- range of interdependence between individuals-- association can be long term and interdependence is high or association can be loose- facillitate- enable something to happen- positive interaction- increasingly significant as succession progresses-can provide better resource availability and refuge from physical stress, competition and predation as communities get more complex |
| Mutualism | Interaction between organisms of 2 species from which both benefit- can be high association- eg between fungi and roots of plants in any stage of succession or loose association- eg bird eats insect off deer- gets food while deer is insect free |
| Commensalism | An interaction between two species where one benefits and the other is unaffected is called commensalism. For example, a squirrel finds shelter in an oak tree, which doesn’t gain anything from it. Over time, these relationships can change. For instance, a parasite might evolve to provide a host with a useful molecule, turning the relationship into a commensal one. Similarly, a relationship that was once commensal can become mutualistic, where both species benefit. |
| recycling nutrients | Plants produce food through photosynthesis. Consumers obtain food by eating plants (producers) or other consumers. Detritivores and decomposers break down the remains and waste of these organisms. This process returns minerals to the soil, which plants can then absorb. Unlike energy, which flows in a straight line, minerals cycle between living (biotic) and non-living (abiotic) parts of the ecosystem. |
| Carbon cycle | carbon is main component of all organic molecules including carbs, fats and proteins- during day- plant photosynthesis converts CO2- from air into carbohydrate (glucose)- all organisms return it to CO2 in respiration- atmospheric conc of CO2 has fluctuated somewhat over time but in last |
| What human act causes more CO2 to be released | Burning fossil fuels- releases CO2 that was previously locked up in them Deforestation - removes large amounts of photosynthesising biomass and so less CO2 being removed from atmosphere- |
| Carbon cycle- 3 major processes | respiration- CO2 added to air by respiration of animals, plants and microorganisms Photosynthesis- takes place on so great a scale- that it re-uses- on a daily basis almost as much CO2 that is released into the atmosphere Decomposition- production of carbohydrates, proteins and fats contributes to plant growth and subsequently to animal growth through complex food webs- dead remains of plants and animals are then acted upon by detritivores and saprobionts- release CO2 back into atmosphere |
| Carbon cycle- where is carbon stored | Carbon is stored in various forms: In the atmosphere (as CO2) In sedimentary rocks In fossil fuels like coal, oil, and gas; coal is almost pure carbon In soil and other organic matter In vegetation (e.g. as cellulose) Dissolved in the oceans (as CO2) |
| Carbon cycle photosynthesis | Autotrophs use the energy of sunlight to 'fix' carbon dioxide, turning its carbon into sugars and other organic molecules This removes carbon from the atmosphere The Calvin cycle is where CO2 is fixed, by the enzyme Rubisco, which carboxylates RuBP Terrestrial plants use gaseous CO2 directly from the air Aquatic organisms use CO2 dissolved in water As much CO2 is fixed from ocean microorganisms, as from terrestrial plants |
| Carbon cycle- sedimentation | When plants die and aren’t fully decomposed, their remains can form sediment layers that accumulate over millions of years, trapping carbon in the ground. This sediment can become energy sources like peat and coal. When aquatic organisms die, they create sediments on the sea floor, which can turn into fossil fuels like oil and gas. Shells and calcium-rich parts can form sedimentary rocks like limestone. The remains of life forms over billions of years have shaped the biosphere and continue to be recycled. |
| Carbon cycle - respiration | All life forms respire, including autotrophs Heterotrophs rely on respiration for all their energy needs Respiration puts CO2 into the atmosphere, in the opposite direction to photosynthesis CO2 is released in the Link Reaction and the Krebs Cycle of aerobic respiration Anaerobic respiration also releases CO2 into the atmosphere, via fermentation by yeast, moulds and bacteria |
| Carbon cycle- feeding and decomposition | Feeding Carbon is passed from autotroph to heterotroph during feeding Carbon is also passed from primary consumer to secondary consumer Biomass transfer always includes the transfer of carbon, the main element in biomass Decay & Decomposition Dead plants and animals are fed upon by detritivores and decayed by saprophytes Releasing carbon into the surroundings Supplying carbon to the detritivores Supplying carbon to the saprophytes Waste matter such as faeces and urine is used by decaying saprobionts Such processes can release CO2 back into the air |
| carbon cycle diagram- save my exams | |
| In aquatic ecosystems | Carbon dioxide as HCO3- ions undergoes same process as regular CO2- but is incorporated into calcium carbonate in mollusc shells and arthropod skeletons- sink after animals' death- become components of chalk, limestone and marble- lost from biosphere but geological processes can expose them to the atmosphere they are eroded releasing CO2 back into air- look at diagram-p84 |
| Human impact on carbon cycle | deforestation- rate at which CO2 is released from atmosphere reduced or when trees are cut down they're burned or left to decay- release CO2 into atmosphere- Climate change- changes in global and regional climate patterns eg changes in average temperature, wind patterns and rainfall- rise in atmospheric CO2 and rise of other greenhouse gases is thought to be the cause- burning fossil fuels and deforestation- CO2 is a greenhouse gas absorbs radiation from earth - if accumulated in excess- leads to global warming |
| Greenhouse effect | Greenhouse gases in the atmosphere, like CO2, methane, nitrous oxide, CFCs, ozone, and water vapor, act like glass in a greenhouse. They let high-energy solar radiation pass through to Earth's surface. Most of this energy is absorbed by the Earth, which then re-radiates it as lower-energy infrared radiation. These gases re-radiate this energy, allowing it to be absorbed back by the Earth's surface. This natural process is essential at certain levels to sustain life. |
| Global warming | more greenhouse gases- enhanced greenhouse effect- concern over human effect on increased greenhouse gases- even if greenhouse gases stopped immediately their influence would still have an effect- global processes take time to slow down |
| global warming effects | weather change, polar caps melting/ flooding, more frequent fires, ocean PH decreases as more CO2 dissolves- fish secrete mucus to protect gills but can then not do gas exchange/ coral is mostly calcium carbonate- soluble in acid, ocean temps rise- corals expel mutualistic algae- lose colour and source of carbs- destroys coral reef ecosystems |
| Global warming effects pt2 | , Water availability is decreasing in tropical areas, and animals often migrate instead of adapting slowly. Climate change shifts fishing areas and crop growing zones. Pests and pathogens may change their distribution, threatening the health of plants and animals. There are concerns about malaria from mosquitoes. While warmer temperatures may increase crop yields, excessive heat can harm or kill crops. |
| Global warming and farming-CO2 | CO2 comes from the decomposition of organic matter in the soil. Better farming practices can improve soil quality: Soil Tillage: Leave crop residues on the surface to reduce erosion, improve water use, and add organic matter to the topsoil. Cover Cropping: Use plants like clover to protect and enhance the soil between crops, improving soil structure and adding organic matter. Crop Rotation: Helps reduce pests and prevents mineral depletion in the soil. |
| Global warming and farming-methane | Methane- can be produced by digestive activities of farm animals used in meat or dairy industries- can be solved by- reducing dietary intake of meat and dairy, high sugar grasses oats, rapeseed and maise in cow's diets to reduce methane released |
| Global warming and farming-methane- pt2 | or... Methane is produced by decomposition in wet soils, like rice paddies. To reduce this, use rice varieties that thrive in drier conditions and those that yield more. Adding ammonium sulfate can promote microorganisms that don't produce methane in paddy fields under certain conditions. |
| Global warming and farming-others | Nitric oxide and nitrous oxide can come from waterlogged, low-oxygen soils. Improving drainage can help aerate the soil. Low and fluctuating water supplies, caused by low rainfall and high temperatures, can be addressed by using drought-tolerant crops. Rising sea levels can flood cultivated land with salt water. This can be mitigated by growing salt-tolerant crops. |
| Carbon footprint | Using an item produces greenhouse gases, but making the raw materials, transporting, and disposing of it creates even more. A carbon footprint measures the total CO2 emissions from a person, product, or service in a year. Nitrous oxide is 298 times more potent for global warming than CO2, and methane is 25 times more potent. The impact of other greenhouse gases is expressed as CO2 equivalents. While crops absorb CO2 as they grow, they also have indirect sources of greenhouse gases. |
| Indirect sources of greenhouse gases for plants | Production of farming tools, production of insecticides, herbicides, fungicides, and fertilisers Farm machinery powered by fossil fuels Transport of produce- most crops are shipped hundreds of miles to processing plants before distribution |
| To reduce production of greenhouse gases | Recycle packing materials. Drive less. Use less heating and air conditioning by insulating your home and wearing appropriate clothing. Choose a diet with less animal protein, especially red meat, and reduce consumption of rice due to methane emissions. Avoid foods that are heavily processed, packaged, or transported long distances. Avoid food waste- turn to compost Plant trees in deforested regions |
| Nitrogen cycle | The nitrogen cycle shows how nitrogen is recycled in ecosystems Plants and animals require nitrogen in order to produce proteins and nucleic acids (DNA and RNA) About 78% of the atmosphere is actually nitrogen gas but plants and animals cannot access the nitrogen in this gaseous form Instead, they rely on certain bacteria to convert the nitrogen gas into nitrogen-containing compounds, which can be taken up by plants The nitrogen cycle shows this conversion, as well as how the nitrogen in the nitrogen-containing compounds is then passed between trophic levels or between living organisms and the non-living environment |
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