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OCR 21stC Science B3

OCR 21st Century Science B3

A species is a group of o[]s that can breed together to produce [] offspring organisms--fertile--.
Adaptation of living organisms to their environment, increases the species' chance of [] by making it more likely that individuals will []e to [] survival--survive--reproduce--.
[Recognise, when given data, how an organism has adapted, and explain the advantage] - B4
Living organisms depend on the e[] and other s[]s for their survival environment--species--.
There is com[]ion for re[]es between different s[]s of animals and plants in the same h[] competition--resources--species--habitat--.
[Explain the interdependence of living organisms by using food webs] - [#B4#]
Nearly all animals are ultimately dependent on energy from the [], as []s tend to be at the bottom of the food chain, and they use []t for photosynthesis sun--plants--sunlight--.
Plant's absorb a small percentage of the Sun's e[] for the process of [] energy--photosynthesis--.
Absorbed energy from photosynthesis is stored in the c[]s that make up a plant's c[]s chemicals--cells--.
Energy is transferred between organisms in an ecosystem: (a) when organisms are [] eaten-- (b) when [] organisms and w[] materials are consumed by d[] organisms (d[]ers and d[]res) dead--waste--decay--(decomposers or detritivores)--.
Energy passes out of a food chain at each stage via []t, []te products and un[]n parts, hence heat--waste--uneaten-, hence limiting the [] of food chains length--.
Carbon is passed from the atmosphere, as carbon [], to l[] things, passed from one organism to the next in c[] molecules (e.g. carbohydrates), and returned to the a[] as [] [] dioxide--living--complex--atmosphere--carbon dioxide---. This is known as the [] [] carbon cycle--.
Green plants remove carbon dioxide by [] - the carbon becomes part of c[] m[] such as proteins, fats and carbohydrates in the plants photosynthesis--complex molecules--.
When an animals eats a plant, carbon from the plant becomes part of the f[]s and p[]s (etc.) in the animal fats--proteins(etc.)-- Microorganisms and some animals fed on [] material from animals, and the remains of [] animals and plants; the carbon hence becomes part of the []s and d[]us feeders waste--dead--microorganism--detritus.
|Carbon Cycle|A dead animal may be f[]d, leading later to f[] f[], which we b[], releasing [] [] fossilised--fossil fuels--burn--carbon dioxide--. [B5]The animal would have held carbon in the form of c[] m[]s as well as c[] []; the fossil fuels complex molecules--carbon dioxide--. The fossil fuel coal is formed from dead [] material which would hold [] in some form, while crude oil is formed from dead m[] organisms and is a mixture of h[]s plant--carbon--marine--hydrocarbons--.
Materials from living things decay because they are d[]d by m[]s digested by microorganisms--; this process occurs at a quicker rate in w[], m[] conditions with abundance of []. warm--moist--oxygen.
Plants and animals need nitrogen to make p[]s, but they can't get it d[]ly from the air because, as a gas, nitrogen is fairly un[]ve proteins--directly--unreactive--. Plants are able to take up nitrogen c[]s such as n[]s and a[] salts from the s[] compounds--nitrates--ammonium--soil--.
Making nitrogen compounds (which plants can then take up) from nitrogen in the air is called nitrogen []tion, which can happen in three ways fixation--.
Nitrogen fixation path 1: the energy in l[] s[]s nitrogen molecules into nitrogen a[]s, which react with o[] to form nitrogen []s lightning--splits--atoms--oxygen--oxides--. The Nitrogen oxides are washed to the ground by [], where they form [] in the s[] rain--nitrates--soil--.
Nitrogen fixation path 2: Nitrogen []ing [] can be found in the s[] and the root n[]es of leguminous plants fixing--bacteria--soil--nodules--;-- these fix nitrogen [] into nitrogen []s gas--compounds--.
Nitrogen fixation path 3: The H[] process is used by industry to produce a[] from nitrogen and h[] Haber--ammonia--hydrogen--. Ammonia is used to make nitrogen []s that are used as []er by farmers compounds--fertiliser--.
Nitrogen is recycled through the environment in the processes of: (a)nitrogen []tion to form nitrogen []s including nitrates; (b) conversion of nitrogen compounds to [] in plants and animals fixation--compounds--; protein--; (c)transfer of nitrogen []s through f[] c[]s; (d)e[]tion, d[] and d[] of plants and animals resulting in release of []s into the soil (c) transfer of nitrogen compounds through food chains; (d)excretion, death and decay of plants and animals [e.g. by [] ] resulting in release of nitrates into the soil--; (e) uptake of []s by plants; (f)de[]ion microorganisms--nitrates--;--dentification--.
|Denitrification| In some conditios, denitrifying b[] in the s[] break down n[]s bacteria--soil--nitrates-- and return [] to the [] nitrogen--air--. This is usually in w[]ged so[] and improving d[]ge reduces this effect, making the soil more f[]e waterlogged soil--drainage--fertile--.
Environmental change can be measured using non-[]ing indicators, including n[]e levels, t[] and c[] [] levels living--nitrate--temperature--carbon dioxide--.
Climate and environmental change can be measured using living i[]rs indicators--, such as py[]on and a[]ic r[]er o[]ms pytoplankton--aquatic river organisms--; the d[]ion and a[]nce of pytoplankton change as the temperature of surface water rises distribution--abundance--.
Life on Earth began approximately [] million years ago 3500--.
Life on Earth (including species that are now extince) evolved from very [] l[]ing things simple--living--.
There is v[]ion between individuals of the same species and some of that is []ic and can be passed on to []g variation--genetic--offspring--.
Genetic variation is the result of changes that occur in []s ([ ]ion) genes (mutation)--.
Mutated genes in [] cells may be passed on to offspring and may produce new []cs sex--characteristics--.
The theory of evolution states that evolution happens by n[] []ion. The key points are that: individuals in a species show a wide range of []ion, because of difference in thier []s natural selection--variation--genes--; individuals with characteristics most suited to the e[] are more likely to s[]e and r[]e environment--survive--reproduce--; the genes that allow these individuals to be successful are pased to their [], leading to an [] in the number of individuals displaying the beneficial []ic in posterity offspring--increase--characteristic--.
With selective breeding, we choose the c[]s we want in an animal or plant, then breed together a [] and [] showing some of those c[]s characteristics--male--female--characteristics. From the offspring produced, breed the ones that show the [] the most characteristic--.
Natural selection and selective breeding both produce c[]es in animals and plants changes--; the difference is that natural selection occurs in [], but selective breeding only occurs with [] in[]tion nature--human intervention--.
Individuals that are poorly adapted to thier environment are less likely to s[] and r[] survive--reproduce--. As a result, their genes are [] likely to be passed on less--: given enough time, a species will enventually e[] evolve--.
Variation can be caused by both []s and the [], but it is only variation caused the []er [<--latter/former] that can be inherited genes--environment--former--.
Most evidence for evolution comes from f[] [] fossil record-- - fossils show how much organisms have c[]ed over []e changed--time--. Other evidence comes from analysis of s[]es and d[]es in the [] of organisms similarities--differences--DNA--.
Darwin's theory of evolution was the result of ma ny o[]ions (e.g. about d[]s) and c[]e thought observations(e.g. about dodos)--creative--.
Jean-Baptiste Lamark proposed an alternative theory to Darwin's at the start of the 1[]th century - it suggested the passing on of a[]ed characteristics 19th--acquired--. However, Darwin's theory is a better scientific explanation as it fits with advances in understanding of []cs, and there's no e[] or m[]m for inheritance of acquired characteristics. genetics--evidence--mechanism--.
Organisms are classified into groups according to similarities and differences in []cs including p[] features and []A characteristics--physical [e.g. the skeleton in vertebrates]--DNA--.
Organisms are classified at different levels, arranged in an order progressing from l[] groups containing m[] orgamisms with a small number of characteristics in []n (e.g. k[]) large--many--common--kingdom-- []er groups containing []er organisms with [] characteristics in common (e.g. s[]s smaller--fewer--more--species--.
Classification is applied to not only living, but also []l organisms fossil--.
The classification of living and fossil organisms can help to: a)make sense of the enourmous []y of organisms on Earth diversity-- b)show the e[]y relationships between organisms evolutionary--.
Biodiversity refers to the v[] of life on Earth, including: a)the number of different s[]s (b)the []e of diifferent types of organisms (e.g. plants, animals and microorganisms) (c) the []ic []ion within species variety--species--range--genetic variation--.
Biodiversity is important as it boosts ecosystem p[]y where each species, no matter the size, has an important r[] to play productivity--role--. For example, a larger number of plant pecies means a greater v[]y of crops; greter species diversity ensures better natural s[]ty for all life forms variety--sustainability--. Biodiversity is also important for medicine, as modern researchers are looking more and more towards our n[]l b[]l resources natural biological--.
The rate of extinction of species is []ing increasing--: this may be due to the []ion of habitats and c[]e []e destruction--climate change--.
Maintaining biodiversity to ensure the c[]ion of different species is one of the keys to s[]y conservation--sustainability--.
Sustainabilty (in this case) means meeting the []s of people today without d[]ing the Earth for future generations needs--damaging--.
Large-scale monoculture farming is not s[]ble because it does not maintain b[] sustainable--biodioversity--.
Sustainability can be improved by consideration of m[]ls and e[] used and p[] created materials--energy--pollution--.
It is preferable to decrease the use of some materials, including packaging materials, even when they are biodegradable, because of: a)the e[] used in their p[]ion and tr[] (b)slow de[]tion in o[] deficient landfill sites energy--production--transport--decomposition--oxygen--.
Humans are involved in the recycling of carbon through the environment when they []re respire. Carbon is recycled through the atmosphere through processes including c[]tion, r[]tion, ph[] and de[]tion combustion--respiration--photosynthesis--decomposition--.
Lichens are plants that grow in e[]ed places such as rocks or tree bark; they need to be good at absorbing []r and []ts to grow there exposed--water--nutrients--. In fact, rainwater contains just enough []s to keep them alive; a[] []ts dissolved in rainwater, especially [] []ide, can d[] lichens, and prevent them from []ing nutrients--air pollutants--sulphur dioxide--damage--growing--. This makes lichens natural []rs of air pollution; in places where no lichens are growing, it is often a sign that the air is heavily polluted with [] [] (especially but other pollutants apply) indicators--sulphur dioxide--.
Many []tic in[]tes cannot survive in polluted water thus their presence or absence indicates the extent to which a body of water is []ed aquatic invertebrates--polluted--.
An indicator species that a body of water is clean is m[] l[]/m[] n[] mayfly larva/mayfly nymphs. An indicator species that the level of water pollution is low is f[] s[] freshwater shrimp.
An indicator species that the level of water pollution is high is w[] l[] water louse. An indicator species that the level of water pollution is very high is sl[] sludgeworm.
Sludge worm is an indicator species that the level of water pollution is .[..], while freshwater shrimp is a natural inidicator that the level of water pollution is [...] very high--low--. The water louse is a natural indicator that the level of pollution in a body of water is [...] while the mayfly larva is an indicator species that the water is [...] high--clean--.
A new species may be produced in the process of evolution via the combined effects of []tions, []al changes, [] []tion and []ation mutations--environmental changes--natural selection--isolation--. Isolation contributes to evolution as it s[]s the gene p[]l apart, so no more g[]ic mixing spits-- gene pool-- genetic--; it means that isolated groups may experience different con[]s under which []al [] occurs, and eventually []ve into a different s[] conditions--natural selection--evolve--species--.
A change in the environment may cause a species to become e[]t, for exampe if (a)the environmental conditions change beyond its limits to a[] extinct--adapt-- (b)a new species that is a c[], p[] or d[] orgaism of that species is introduced competitor--predator--disease-- (c)another species (animal, plant or microooganism) in its [] [] becomes extinct food web--.
Created by: Toluo



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