GCSE Biology

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GCSE Biology
2012-04-30 12:38:21
genetic variation

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  1. one of the biggest advanatges of gentically engineered bacteria is they can
    make exactly the protiens needed andf in very pure form .
  2. what can geenitically enegineered genes be used for
    • to improve growth rates of planst and animals
    • to improve the food value of crops and to reduce the fat levels in meat
    • they are used to produce plants which make their own pesticides
  3. what are the advantages of GM crops
    • they may be genetically engineered so that they are resistant to herbicide meaning a farmer can srpary his weeds without killing his crops
    • GM crops increase the yeild of a crop , making more food
    • people living in LEDC'S often lack nutrients in their diet and GM crops could be conatin the nutrients that are missing
  4. what are the disadvanatges of GM crops
    • the GM crop seeds may be expensive for farmers
    • pollination may mean that if GM crops are nearby weeds the gene for herbicide resistance may be transfered to the weeds
    • we dont know wheter eating GM crops over a long period of time will cause health problems
  5. what are the ethical issues of genetic engineering
    • humans may not have the right to gentically alter nature for their convinience and profits in some peoples opinions
    • vegetarians may find it offensive to put animal genes into plants
  6. most cells in your body have a nucleus . the nucleus conatins
    your genetic material in the form of chromosomes
  7. the human cell contains ..... pairs of .....
    • 23
    • chromosomes
  8. chromosomes carry
    genes . different genes control the devlopment of different characteristics
  9. a gene is a short length of the chromosome which is quite a long length of ......
  10. sexual reproduction involves the
    fusion of of male and fema tle gametes . Because there are two parenst , the offspring contain a mixture of their parents genes
  11. in asexual reproduction there is only :
    one parent . there's no fusion of gametes , no mixing of chromosomes and no genetic variation between parent and offspring , the offspring are genetically identical to the parent - they are clones
  12. how does asexual reproduction work
    • X shaped chromosmes have two identical halfs
    • so each chromosome splits down the middle
    • to form two identical sets of half chromosomes (i.e. two identical sets of DNA strands)
    • a membrane forms around each set
    • and the DNA replicates itself to form two identical cells with complete sets of X shaped chromosomes