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.... and ..... developed by a process called .... . this takes place over .... of ..... . the Greek scientist Anaxiamander first came up with the idea of ..... in about 520 BC . he said that life origionally started off as a sort slime and over many years developed into other forms of life . over the centuries there have been many ideas as to how this has happened
- plants
- animals
- evolution
- millions
- years
- evolution
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in 1801 Jean-Baptiste .... came up with the theory that .... .... features that had been .... by thier .... . If thie theory were true , a marathon runner would produce children who could also run marathons . Today we can see that this is not true . To run a marathon , people have to train hard , regardless of whether or not thie rparents are atheletes
- Lamarack
- offspring
- inherited
- developed
- parents
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Charles Darwin's theory is know as ..... .... , this theory was oublished in a book in 1859 called the ..... ... ...... , this thoery is now accepted as correct by most people . this thoery says that in any group of organisms , .... .... ..... or ..... might have ..... some features which allow it to ..... ... or ...... .... than the others
- natural selection
- origin of species
- one particular plant
- animal
- inherited
- grow better
- reproduce more
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it was thought that millions of years ago giraffes had short necks and fed on grass . however there was ...... .... in the length of thier necks . when there was little rain and the grass died , any giraffes with longer necks were able to eat leaves on trees . the giraffes that could not reach the leaves .... . only the giraffes with longer necks .... and ..... . this happened many times over millions of years , until today all giraffes have very long necks . the long necked giraffes were .... .... to thier ..... . they were the .... scince they ... best with thier ..... . they were most likely to survive and so this process is called ..... .... the ..... . when this process happens again and again you get ..... . evolution evenmtually produces ... ...
- inherited variation
- died
- survived
- reproduced
- best
- adapted
- environment
- fittest
- fitted
- environment
- survival of the fittest
- evolution
- new species
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what do you understand by the term evolution
it is the slow continual change in characteristics of species over a very long time . All living things on earth have developed from the first simple life forms that arricved 3 billion years ago
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how would lamracks thoery explain why giraffe's neacks got longer
the first giraffes that were unable to get food from the ground beacuse the grass had died stretched to get food , so its neck got longer , the giraffe then passed on the feature of a long neck to its offspring
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in the evolution of giraffes , why did shorter necked animals die
becuase they were unable to reach the food they needed therefor they starved to death
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what is meant by survival of the fittest
these animals are the animlas that were well adapted to thie environment . they were fittest as they best fitted to thier environment . and the phrase is know as survival of the fittest because these fit animals were most likely to survive and pass on the feature that enabled them to be well adapted to thie environment
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explain why these features might help the organism to survive better .
a) a polar bear that had thicker fur than usual
b) an owl that ate fruits as well as small animals
c) a rabbit that was a particuarly fast runner
- a) it will insulate the polar bear
- b) there is more food available that is easier to eat
- c) it will be able to escape predators and catch prey eaiser
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plants also evolve . explain how a tree that is able to grow faster and taller than others around it might produce a whole forest full of fast growing , tall trees
the first fast growing tree that is well adapted to it environment will be able to compete sucessfully , so it is most likely to survive (known as survival of the fittest) . the tree is likely to live long enough to reproduce and pass on these genes that enabled it to be well adapted to its environment . over generations all the trees in the forest will have these succcessful genes
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different animals are adapted and suited to different environments . when Darwin visited the Galapagos Islands he saw that finches with different beaks live on different islands that had different food sources . Individuals with chracteristics most suited to the environment are more likely to survive to breed successfully . the genes which enabled these individuals to survive are then passed on to the next generation
how did the different types of beaks arise in the first place
in each environment there would have been natural selection and survival of the fittest . in each environment at first there will have been a bird that had beaks well adapted to thier environment . these birds would have lived longer and would have been able to breed and pass on these successful genes . over generations all the birds on that island will have had well adapted beaks . however as each environment is different the birds in each environment will have differently adapted beaks . however now they are all likely to be well adapted to thier environment
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name a beacteria that is resitant to a whole range of antibiotics
the bacteria that caused MRSA
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describe evolution by natural selection in 5 stages
- a) there is variation in the individuals of species
- b) some individuals will die before they reproduce
- c) the individuals that survive will be the ones with the best survival characteristics
- d) when these individuals reproduce , they will produce more individuals with the good survival chracterisitics
- e) so there will be more individuals with the good chracteristics in the next generation
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explain what happens to the bacteria when a man is infected with a bacterial pathogen
the beacteria once inside him will reproduce rapidly , therefor there will be lots of bacteria , this will meake him ill . each beacteria will show variation
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what will happen to the bacteria inside a man if he has been given antiiotics for a bacterial pathogen
the natibiotics will kill most of the bacteria especially the weak variation
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what will happen to the beacteria inside a man if he feel better before he has finished the antibiotic course , so he stops taking them
some bacteria will not be killed as the antibitotic has not had long enough to attack and properly kill the more resistant bacteria . this bacteria will create mutant beacteria that is resitant to the antibiotics . these mutant becateria survie and pass on the mutant genes by reproduction .
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list four reasons for extinction
- preditation or competition
- habitat destruction or modification
- overexplotion
- disease
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give an example of how prediation or competion can cuase extinction
3 million years ago , North and South America joined . the species that lived in each continent were very different . when the continents joined some species moved from one continent to the other . after this many species became extinct . some died because other species moved into thier ecosystem and outcompeted them of food and space . others died because new predator species came into thier ecosystem and killed off whole populations of prey species
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explain how habitat destruction or modification can cause species to become extinct
our planet is continually changing , causing habitats to be altered and modified . Natural changes usually occur at a gradual pace . however when changes occur at a fats pace , there is little of no time for the species to adapt to thier modified habitat . Humsn change habitats quickly . For example we cut trees down leaving giving species no warning or time to move to a different habitat , or to adapt to thier habitat without trees meaning a lot of species will die .
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explain mass extinctions caused by natural habitat modification
- mass extinctions can be linked to rapid changes in sea level or temperature . for example about 65 million years ago a meteorite caused mass extinction of dinsoaurs
- volcanoes can also cause mass extinction s, a series of major volcanic erruptions will produce huge clouds of ash and dustb that will block the sunlight and cause a global winter which may kill some plants and animals
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define mass extinction
an event in which a large number of species become extinct during the same period
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explain how overexplotion of animals may lead to extinction
some species are being used at a rate that doesnt allow reproduction to happen quick enough in therfor there are few new species of that animal produced however there are many animals of the species that are killed so teh population of that species decreases
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explain how disease can cause extinction
many wild anaimals arent vaccinated against disease . therefore if a few animals get infected witha deadly disease , there could be an outbreak of this deadly disease and if none of these animals were immune to this disease a whol epopulation could be wiped out
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the theory of evolution states that :
all species of living things that exist today have evolved from simple life forms , which first developed more than 3 billion years ago . therefor organisms have descended from a common ancestor
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an evolutionary tree :
mpas the evolution of different organisms from a common ancestor by studying the similarities and differences of these organisms
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a mutation is :
a spontaneous change in genetic information
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the two type of mutations are
gene mutations and chromosome mutations
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the chances of a mutation occuring is increased by exposure to :
most mutations are harmful , but beneficial mutations can increase and organisms chances or survival
- gamma radiation
- x-rays
- ultraviolet rays
- certian chemicals
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natural selection
due to sexula reproduction , there is variation between members of species
weaker members of species can die from : ..... , ....... .. ... , ........ or .......
the organisms with the best chractreristics are more likely to .... and .... this is known as ...... .... the .... . the genes that enabled them to survive are .... ... the next generation
- disease
- lack of food
- preditation
- competition
- survive
- breed
- survival of the fittest
- passed onto
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extinction means :
that a species that once existed has been completely wiped out
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causes of extinction may be
- climate change
- a new disease
- a new competitor
- a new predator
- the habitat may be destroyed
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