Edexcel B Biology - Topic 3

• Classification is the process of naming organisms into groups based on characteristics.
• Organisms can be put into one of the five kingdoms:

  • Animalia
  • Plantae
  • Fungi
  • Prokaryotes
  • Protoctista
• The Binomial System:

  1. Kingdom.
  2. Phylum.
  3. Class.
  4. Order.
  5. Family.
  6. Genus.
  7. Species.
• The analysis of molecular differences in different organisms to determine the extent of their revolutionary relationship is known as molecular phylogeny.
• The three domains are:

  • Bacteria.
  • Archaea.
  • Eukaryota.
• Gel electrophoresis:

  1. Make wells in agarose jelly.
  2. Put DNA fragments cut with restriction endonuclease enzymes in them.
  3. Dye the DNA with something fluorescent.
  4. Turn on a current.
  5. DNA has a negative charge so it moves towards the anode.
  6. Turn the current off.
  7. Turn the UV light on.
  8. Different bands represent different amino acids.
• The scientific community evaluates data by:

  • Publishing findings in a scientific journal which are presented at scientific conferences.
  • A peer review is then completed.
• Biodiversity is the variety of living organisms in an area.
• Species richness - the number of different species in an area.
• Genetic diversity is a measure of the genetic variation within a particular species.
• Ex-situ conservation:

  • Captive breeding programs.
  • Reintroduction programs.
  • Seed banks.
• In-Situ conservation:

  • Education programs.
  • National Parks and Sites of Specific Interest.
• Anatomical adaptations are physical adaptations.
• Behavioral adaptations are changes in behavior which improves the organisms chance of survival.
• Physiological adaptations are processes involving enzymes/hormones that increase an organisms chances of survival.
• Natural selection is the process in which fitter individuals who are better adapted to the environment are more likely to survive and reproduce and pass on the advantageous alleles to their offspring.
• Natural Selection:

  1. A variety of phenotypes exist within a population due to mutations.
  2. An environmental change occurs and selection pressures change.
  3. Some individuals posses advantageous alleles which give them a selective advantage and allow them to survive.
  4. Alleles are passed onto offspring.
  5. The frequency of alleles in a population changes.
• If two populations become reproductively isolated, new species will be formed. This is due to the accumulation of different genetic information in populations over time due to different environments and selection pressures. This is called speciation.
• Allopatric speciation involves geographical isolation.
• Sympatric speciation involves any other kind of isolation apart from geographical.