SB4

• what are selection pressures and some examples of them?

  Things that affect an organism chance of survival and reproduction e.g. predation, competition, and disease
• How does antibiotic resistance provide evidence for evolution?

  it makes the bacteria better adapted to an environment in which antibiotics are present. So antibiotic resistance becomes more common in a population over time
• How do fossils provide evidence for evolution?

  By arranging fossils in date order, gradual changes in an organism are observed. it shows how species have changed over billions of years
• Which two people developed the theory of evolution?

  Charles Darwin and Alfred Russell Wallace
• What was Darwin’s book called and when was it published?

  On the origin of species, 1859
• How has the theory of evolution affected classification?

  if all living organisms have descended from a common ancestor then we’re all related in someway and were classified by how closely related
• How has the theory of evolution affected antibiotic resistance?

  We now understand you must finish the drug course to prevent resistant bacteria spreading and new antibiotics must be made to fight newly evolved resistant bacteria
• How has the theory of evolution affected conservation?

  Genetic diversity helps populations adapt to changing environments leading to conservation projects to protect species
• What are the 4 homo species in order of oldest to youngest?

  homo habilis: (2.5m-1.5m years ago)

  homo erectus: (2m-0.3m years ago)

  homo neanderthalenis: (300,000-25000 years ago)

  homo sapien: (200,000 years ago-present)
• what is stratigraphy and how does it show evidence for evolution?

  The study of rock layers, older rock layers are normally found below younger layers, so tools and fossils in deeper layers are usually older
• How does the pentadactyl limb show evidence for evolution?

  has 5 digits, The similarity in bone structure shows that species with a pentadactyl limb have all evolved from a common ancestor
• What are the 5 kingdoms?

  Animals, plants, fungi, prokaryotes, protists
• What are the 6 groups that kingdoms are subdivided into?

  phylum, class, order, family, genus, species
• What are the 3 domains?

  archea, bacteria, eukarya
• Which scientist came out of the 3 domain classification system?

  Carl Woese
• What did Woese use to discover that some members of the prokaryote kingdom arent as closely related as people thought and should be split into 2 groups?

  RNA sequencing
• What is selective breeding?

  When humans artificially select the plants/animals that are going to breed, so that genes for particular characteristics remain in the population
• How long does the selective breeding process take?

  Over several generations, and the desirable traits get stronger and stronger until eventually all offspring have the characteristic
• Why is selective breeding useful in agriculture?

  Genetic variation mean some cattle have better characteristics producing meat than others. to improve meat yields, farmers could select cows and breed them
• How is selective breeding useful in medical research?

  in investigating reasons behind alcoholism, rats have been bred with a strong/weak preference for alcohol, allowing the differences between them to be studied
• what is the main problem with selective breeding?

  It reduces the gene pool (the number of different alleles) in a population. this is bad because the best animals/plants are always used for breeding
• What is the problem with inbreeding?

  It can cause health problems as there is more of a chance of organisms inheriting harmful genetic defects when the gene pool is limited
• What happens when a new disease appears during selective breeding?

  There isn’t much variation in the population, so there’s less chance of resistant alleles being present. if one stock is killed by disease the others are likely to too
• What is tissue culture?

  Growing cells on an artificial growth medium
• What are the advantages of growing plants through tissue culture?


  Plants grow in this way can be made very quickly, in a very little space, and can be grown all year round
• What are plants could use by tissue culture is also known as?

  Clones, genetically identical organisms
• What are the advantages of clones being produced by tissue culture?

  Lines of clones or with the samr beneficial features, eg pesticide resistance or tasty fruits etc
• What is the 1st stage of tissue culture? (plants)

  Choose the plant you want to clone based on its characteristics
• What is the 2nd stage of tissue culture? (plants)


  Remove several pieces of tissue from the parent plant. you get the best results if tissue is taken from fast growing roots or shoot tips
• What is the 3rd stage of tissue culture? (plants)


  Grow the tissue in a growth medium containing nutrients and growth hormones, this is done under aseptic conditions to prevent growth microbes that may harm the plant
• What is the 4th stage of tissue culture? (plants)


  As the tissue produces shoots and roots, they can be moved to potting compost to carry on growing
• How is animal tissue culture used in medical research?

  It means you can look at the effects of a particular substances or environmental changes on the cells of a single tissue without complications from the whole organism
• What is an example of tissue culture in animals?

  Investigating the effect of glucose on cells in the pancreas, by growing pancreatic cells in culture
• What is the 1st stage of tissue culture? (animal)

  Get a sample of the tissue you want to study
• What is the 2nd stage of tissue culture? (animal)

  The cells in the sample are separated from each other using enzymes
• What is the 3rd stage of tissue culture? (animal)

  They are placed in a culture vessel and bathed in a growth medium, containing all the nutrients that they need, allowing them to grow and multiply
• What is the 4th stage of tissue culture? (animal)

  After several rounds of cell division, the cells can be split up again and placed in separate vessels to encourage further growth
• What is the 5th stage of tissue culture? (animal)

  once the tissue culture has been grown, it can be stored for future use
• What is the purpose of restriction enzymes?

  They recognise specific sequences of DNA and cut the DNA at these points. the pieces of DNA are left with sticky ends where they have been cut
• What is the purpose of ligase enzymes?

  Used to join two pieces of DNA together at their sticky ends