AQA Biology B1b Revision

Summary of subject knowledge for AQA Biology B1b

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Competition in Plants

  • Plants compete for water, nutrients and light
  • Some spread seeds over wide area so they don't compete with each other eg, coconuts can float for miles on ocean currents
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Natural Selection

  • New forms of genes mutate from existin genes
  • Animals with genes best suited to the environment live and reproduce
  • Succesful genes are then passed on to the next generation
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Extinction

Can be caused by

  • Changes the the environment
  • New predators
  • New competitors
  • New diseases
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Theories of Evolution

  • Fossils provide evidence of how much/little organisms have changed
  • Difficult to know how life began - no direct evidence
  • Theory of Evolution = all species alive today and species that are extinct evolved from simple life forms - 3 billion years ago
  • Natural Selection = Evolution
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Sustainable Development

  • looking after the environment and improving your quality of life at the same time
  • using natural resources wisely
  • by; recycling, being energy efficient and using cars less.
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Planning for the future

  • Sampling from differnet areas can be used to estimate population growth
  • Environmentalists believe it is important not to build on sites of special scientific interest, so therefore they need to test the land first.
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Cloning

  • cuttings - taking a small piece of stem of leaf and growing it on in the right conditions to produce a new plant
  • tissue cloning - getting a few cells from a desirable plant to make a big mass of identical cells each which can produce a tiny identical plant
  • Asexual reproduction - reproduction which only involves one parent, there is no joining of gametes and the offspring are genetically identical to the parent
  • Embryo cloning - splitting cells apart from a developing embryo before they become specilised to produce several identical embryos.
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New ways of cloning animals

  • Fusion cell cloning is a form of asexual reproduction
  • Dolly the sheep was created through fusion cell cloning
  • in adult cell cloning, a whole cloned animal can result. The nucleus from a cell from an adult animal is transferred to any empty egg cell from another animal, a small electric shock fuses the cells.
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Adaptation in Animals

  • All living things have adaptations which make them live
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Adaptation in Plants

  • plants lose water all the time by evaporation from their leaves
  • plants which live in dry places have adaptations which help to reduce water loss. These adaptations may often include reduced surface area of the leaves
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Competition in animals

  • Animals compete for water, food, space, mates and breeding sites
  • the most successful ones survive and pass on their genes to the next generation
  • some animals have adaptations which make them good competitors, eg, camoflage, poisons or speed
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The effects of population

  • the population is rapidly increasing as is the standard of living
  • more waste is being produced causing pollution
  • humans reduce the amount of land available
  • raw materials are being used rapidly
  • out activity has changed the balance of nature
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