OCR gateway biology B2

module 2 - understanding our eniroment

  • Created by: lucy
  • Created on: 14-05-11 15:11


an ecosystem is all the different organisms living together in a particular environment 

  • a natural ecosystem is one where humans don't control the processes which going on with in it
  • eg: woodlands,lakes,rainforest's,oceans
  • an artificial ecosystem is one where humans deliberately promote the growth of certain living organisms and get rid of other which threaten their well being
  • eg: greenhouses, fish farms,zoos, one crop fields
  • artificial ecosystems have a lower biodiversity
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classification is organising living organisms into grops


the animal kingdom is split into vertabraes and invertabraes. Vertebrae have backbones but inveratbraes do not

the vertabraes are then split into 5 classes

  • FISH- live in water, have scales and gills
  • AMPHIBIANS- exchange gas through their skin, skin is permeable and moist
  • REPTILES- dry scaly skin, adapted to live on land
  • BIRDS- most can fly, feathers,beak
  • MAMMALS- fur/hair covering body, give birth to live young

sometimes newly discovered species dont really fit into any of the categories.These can be living species or fossil ones such as archaeopteryx.

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the binomal speices gives everything a two part name

  • the first part is the genus
  • and the second part refers to the species

things of the same species can breed to produce fertile offspring

  • organisms of the same species can breed to get fertile offspring
  • if you breed two different species you get a hybrid
  • hybrids are infertile which makes them difficult to class as they aren't new species by themselves

unrelated species may have the same species

  • they may have a recent common ancestor so they are closely related
  • they may have adapted to the same enviroment
  • so they're related in environmental and evoulationary terms
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estimating population sizes using a quadrat

  • a quadrat is a square frame enclosing a known area
  • to estimate population size:
  • 1) count all the organisms in 1m quadrant
  • 2) multiply this number by the total area

estimating populataion size using mark-release-capture

to estimate population size

  • 1)capture a sample of the population and mark the animals
  •  2)release them back to the environment  
  •  3)recapture another sample and count how many are marked    
  •  4) no animals in 1st sample x no of animals in 2nd sample /no. of marked animals in second sample
  • the bigger the sample the more accurate it will be
  • the sample may not be representative to the population
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photosynthesis produces glucose and sunlight


6C02 + 6H20 -------> C6H1206+ 602

glucose is converted into other substances

  • glucose is soluble so it can be transported to other places in the plant

1) glucose is used for respiration
2) glucose is converted to lipids and stored in seed
3) glucose is converted to amino acids and makes proteins
4) glucose is turned in cellulose to make cells walls
5) glucose is turned into starch and stored in toors,stems and leaves

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Rate of photosynthesis

there are three factors that control the rate of photosynthesis 

not enough light slows down the rate of photosynthesis- if the light level is raised the rate of photosynthesis will increase, until a certain point

Too little carbon dioxide also slows down photosynthesis- the amount of co2 will only increase the rate of photosynthesis to a certain point after this co2 is no longer the limiting factor 

the temperature has to be just right- as the temperature increase so does the rate of photosynthesis but if the temperature is to high the enzymes will be destroyed so the rate rapidly decreases.

Photosynthesis and respiration are opposite processes 

  • photosynthesis makes glucose and oxygen from carbon dioxide and water
  • respiration makes carbon dioxide and water from glucose and oxygen
  • photosynthesis happens during the day but respiration happens all the time
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interactions between organisms

populations of prey and predator go in cycles

  • if the population of the prey increases then so will the population of the predators 
  • however as the population of predators increase the number of prey will decrease
  • the population of any species is usually limited by the amount of food available

parasites and mutualistic relationships

  • parasites live off a host without giving anything back.This often harms the host which makes it a win-lose situations
  • mutualisms is a relationship where both organisms benefit- so its a win-win relationship
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the polar bear is adapted for cold arctic conditions

  • large size and compact shape keeps surface area to a minimum
  • thick layer of blubber for insulation
  • white fur for camouflage

the camel is adapted to dry desert conditions

  • can store a lot of water without a problem
  • bushy eyelashes to stop sand getting in
  • thick coat which 

the cactus is well adapted for hot dry conditions

  • small surface area to reduce water loss
  • thick waxy layer to reduce water loss
  • sharp spines to stop herbivores eating them

insect pollination have smelling nectar, wind pollination has feathery stigmas

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fossils are the remains of plants and animals 

  • from gradual replacement by minerals
  • from casts and impressions
  • from preservation in places where no decay happens

The fossil record is incomplete 

  • this is because very few dead plants or animals actually turn into fossils and some body parts,like soft tissue, tend to decay away completely
  • there are fossils yet to be discovered that might help to complete the picture
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theories of evouloution

  • only the fittest survive
    • Individuals in a species show a wide range of variation.
    • This variation is because of differences in genes.
    • Individuals with characteristics most suited to the environment are more likely to survive and reproduce.
    • The genes that allowed the individuals to be successful are passed to the offspring in the next generation.

Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed to the next generation. Given enough time, a species will gradually evolve.

  • lamarck thought that if a characteristic was sued a lot in a organisms lifetime the animal would become more developed and it could be passed onto the animals offspring
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Human Impact on the enviroment

human population is increasing 

  • the worlds human population is rising exponentially
  • this rapidly increasing populations puts pressure on the environment
  • the higher standard of living amongst more developed countries demand even more resources   

increasing amounts of pollution are causing...

1) global warming and acid rain- when fossil fuels are burned they cause global warming and sulfur dioxide which causes acid rain                                                  2) ozone depletion- CFC's  which are used in fridges,air conditioning units, and aerosoles break down the ozone layer in the atmosphere which also means we are exposed to more UV light

indicator speices show polloution levels

  • some speices can only survive in highly polluted levels, some spices can only survive in un polluted levels
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Endangered speices

We are endangering many species

human activity is causing a decrease in the population sizes of many speices

  • the fossil fuels we are burning are thought to be causing climate change and plants and animals are unable to adapt fast enough
  • we're destroying habitats so we are damaging thousands of species homes
  • many animals are hunted - some for food, fur coats, jewellery or even for fun
  • humans cause pollution which harms many living things
  • were increasing the competition between species 

there are 5 main ways to protect endangered speices

  • education programme
  • protected habitats
  • legal protection
  • captive breeding
  • creating artificial ecosystems
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Conservation programmes

conservation programes benefit wildlife and humans

  • they protect the human food supply- overfishing has greatly reduced fish stocks in the worlds oceans and conservation programmes mean future generations will have fish to eat
  • reducing the need for chemical pesticides- protecting predators of pests such as ladybirds eating aphids means crops can be grown without using potentially harmful chemical pesticides
  • providing future medicines- many of the medicines we use today come from plants and protecting plants give a greater chance of finding medicines for illnesses such a cancer.
  • cultural aspects- individual species may be important inn a nations or areas cultural heritage ( the bald eagle is being conversed in the USA as it is regarded as a national symbol)
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sustainable developemnt

development has to be sustainable 

as the human population gets bigger

1) we need to produce more food so we'll need more land for farming

2) we use up more energy as we're burning more fossil fuels which will eventually       run out so an alternative energy source needs to be found

3)we're producing more waste and it all needs to be pit somewhere and a lot of its      polluting the earth.

SUSTAINABLE DEVELOPMENT meets the needs of today population without harming the ability of the future generations to meet their own needs.

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