6.2 variation and evolution

• define continuous variation

  numerical data

  can be described using any value
• define discontinuous variation

  usually grouped into named categories

  there are no intermediates, just one group or another
• define intraspecies

  between organisms of the same species
• define interspecies

  between organisms of different species
• define normal distribution

  the similar overall shape of graphs of continuous data
• what are the causes of variation?

  environmental, and inherited (mutations, sexual reproduction)
• define mutation

  when the DNA of an organism is changed. this means they have a new form of that gene
• define genetic engineering

  transferring genetic material (dna) from one organism into a different organism
• define trangenic organism

  an organism that has been genetically modified with DNA from a different species
• define plasmid

  a small, circular piece of DNA found in bacteria, that is extra to their main chromosome
• how did type 1 diabetes used to be treated, and what were the problems this caused?

  pig insulin

  not enough to supply demans

  not perfect (due to side effects)
• what are the advantages of using insulin produced by genetically modified bacteria to treat diabetes?

  much larger quantities

  much purer product

  human rather than pig, so more effective and less side effects
• what is selective breeding?

  speeding up natural selection and evolution, so the desired traits become more common
• what are the disadvantages of selective breeding?

  reduces genetic variations by decreasing the number of allelles

  risk of imbreeding (-> health problems)

  reduces adaptability of a breed if environmental conditions change
• what are the advantages of selective breeding?

  increase frequency of alleles coding for desirable traits

  allows humans to manipulate genetic inheritance to suit their needs
• define evolution

  the process of slow change in libing organisms over a long periods of time as those best suited to surive can breed successfully
• define natural selection

  the process by which evolution takes place

  Organisms produce more offspring than the environment can support only those which are most suited to the environmnet (the fittest) will SURVIVE to breed and pass on their useful alleles/genes
• what are the 3 requirements for natural selection to occur?

  1. natural variation of different characteristics (due to sexual reporduction, and mutations which create new alleles)
  2. over production of offspring
  3. competition for resources
• Explain how natural selection is a mechanism for evolution

  1. overproduction of offspring -> competition
  2. sexual reproduction and/or mutations over many generations creates variety among individuals in population
  3. some of this variety would give the individual an advantage
  4. these individuals with an avdantage are more likely to survive
  5. repeated over successive generations, so species would slowly evolve with characteristics favourable to environment
• Darwin's theory of natual selection compared...

  physical traits
• Darwin studied in ....

  Galapagos islands
• define classification

  organisation of living things into groups according to their similarities
• define species

  a group of organisms with many features in common that can breed successfully to produce fertile offspring
• what are the 6 kingdoms?

  animals, plants, fungi, protista, eubacteria and archaebacteria
• what are the 3 domains?

  eukaryota, bacteria, archaea
• who created the domain system?

  Carl Woese in the 1970s
• what is the main differene between prokaryota and eukaryota?

  prokaryota don't have a nucleus but eukaryota do
• define evolutionary relationship

  how closely related two species are (how long ago the 2 species diverged from a common ancestor)
• define evolutionary tree

  models used to explain the evolutionary links between groups of organisms
• define fossil

  the preserved impressions of organisms often from millions of years ago
• what are the 4 types of fossils?

  rock/mineralised fossils

  amber/resin

  ice fossil

  peat bog
• what is the evidence for the 3 domain system?

  • DNA and genomes. grouped by similar genomes
  • cell division
• Bacteria can evolve quickly because.......

  they reproduce at a fast rate.
• Mutations of bacteria produce...

  new strains
• example of antibiotic?

  penicillin
• the evolution of the bacteria is an example of....

  natural selection
• What are the main steps in the development of resistance?

  1. random mutations occur in the genes of individual bacterial cells
  2. some mutations protect the bacterial cell from the effects of the antibiotic
  3. bacteria without the mutation die or cannot reproduce when the antibiotic is present
  4. resistant bacteria can reproduce with less competition from normal bacterial strains
• name an example of an antibiotic resistant bacteria?

  MRSA
• How to reduce the rate of development of antibiotic resistant strains?

  • doctors should not prescribe antibiotics inappropriately, such as for the treatment of non-serious infections
  • patients should always complete the full course of antibiotics to ensure all bacteria are killed and none do not survive to mutate and form resistant strains
  • the agricultural use of antibiotics should be restricted
• why number of resistant strains has increased?

  misuse of antibiotics