Natural selection and genetic modification

• how does natural selection occur

  • a mutation within the species occurs
  • this causes variation in the species
  • the individual that is best adapted to the environment will survive
  • they will then go on to breed
  • meaning they pass on the beneficial genes
• what did Darwin and Wallace do

  they travelled to islands to research about evolution
• how does antibiotic bacteria supports natural selection

  • bacteria reproduces rapidly
  • eventually a mutation will occur during reproduction
  • if a mutated bacterium is resistant to the antibiotics it will survive exposure to antibiotics
  • then it will go on to reproduce
• how can you prove that organisms have evolved from the same organisms

  by comparing similar structure in similar animals - pentadactyl limb
• what is the pentadactyl limb

  many vertebrates have similar bone structure, even though their limbs look different from the outside due to evolution
• what are vertebrates

  animals with backbone
• how to reduce the chance of antibiotic-resistant strains of bacteria

  • restrict use of antibiotics in agriculture
  • avoid prescribing unnecessary antibiotics
  • finish a course of antibiotics
• what is a species

  individuals breed together to produce fertile offspring
• how is Ardi, Luci and Leakeys fossils proof of human evolution

  Ardi 4.4million years ago : long arms, long toes and could walk upright

  Luci 3.2million years ago : walk upright like a human but a relatively small ape-like skull

  Leakeys fossils 1.6 million years ago : much more like a modern human
• Describe the evidence for human evolution based on stone tools

  • 2.6 million years ago : very basic tools - rocks with sharp edge
  • 1.6 million years ago : complex tools - more sophisticated
  • the more complex tool, the more developed the brain of the user
• how do you determine when the stone tool was in use

  • how deep it was buried ( deeper = older)
  • use known dates of other fossil found at that level
  • compare design to other stone tools that are already dated
• what is the Linnaean Classification System based on

  based on their structure and characteristics
• what are the groups in the Linnaean Classification system

  Kingdom

  Phylum

  Class

  Order

  Family

  Genus

  Species
• what is the three domain system based on

  based on genetic analysis
• what are the groups in the three domain system

  Archaea - primitive bacteria

  Bacteria - true bacteria

  Eukaryotes - protists, fungi, plants, animals
• what is selective breeding

  when humans choose animals and crops to breed based on their genetic characteristics
• what are the steps of selective breeding

  1. choose parents who most strongly display the desired characteristic - breed them
  2. from the resultant offspring (children), choose offspring that best displays the desired characteristics - breed them
  3. repeat this over many generations until all the offspring show the desired characteristic
• what are the dangers of selective breeding

  • reduced variation
  • inbreeding - some breeds become particularly susceptible to disease
• what are the uses of selective breeding

  • can improve yield
  • can be used for medical research
• what is tissue culture

  a process which involves growing genetically identical cells in a lab under sterile conditions
• what are the stages of tissue culture

  1. a tissue sample is taken from parent plant
  2. the cells are sterilised
  3. the samples are treated with plant hormones to trigger cell division and growth on an agar plate
  4. a ball of cells called callus forms and more hormones added to cause roots and stems to grow
  5. the clone of parent plant is now planted into soil
• what are the uses of tissue culture

  • medicine : study viruses, grow artificial tissues
  • plants : produce genetically identical plants quickly
• what is genetic engineering

  a process which involves modifying the genome (DNA) of an organism to introduce the desirable characteristic
• what are the steps of genetic engineering

  1. cut the plasmid (from bacteria) with restriction enzyme
  2. cut the gene you want with restriction enzyme
  3. insert gene you want into plasmid with ligase enzyme
  4. sticky ends on two genes are complementary
  5. recombinant plasmid is inserted back into bacteria cell
• what are the advantages of genetic engineering

  • generally show increased yields
  • help provide nutrients usually missing from diets
  • prevents inherited disease
  • improves food production efficiency
• what are the disadvantages of genetic engineering

  • long term health effects unknown
  • considered unethical
• what are the disadvantages of agricultural solutions

  • cost of fertilisers are high so farmers afford less and yields suffer
  • fertilisers can leak into surrounding environment and contaminate water sources
• what are the advantages of using agricultural solutions

  • fertiliser can increase growth rates when minerals are a limiting factor