evolution and classification

• adaptations: examples of variation that help an organism survive in a particular environment
• species: a group where all organisms can interbreed to produce FERTILE offspring.

  for example, if a horse and a donkey breed, the offspring will not be fertile because they are not in the same species.
• 1. Kingdom
  2. phylum
  3. class
  4. order
  5. family
  6. genus
  7. species
• the 5 kingdoms are plants, animals, fungi, prokaryotes and Protoctista [anything that's not the other 4]
• species: members of a species tend to be more similar to each other than to any other species.
• natural selection occurs when there is competition between different genotypes within a population for limited resources such as food or mates. The best adapted genotype survives and reproduces so its alleles become more common in the next generation.
• natural selection

  some genetic variants have characteristics that are better suited to their environment. this means that this organism has an advantageous phenotype [in this particular environment]. these individuals have a better chance of surviving and reproducing, passing down the genes for this advantageous phenotype.
• evolution: the change of inherited characteristics of a population over time, through the process of natural selection.
• being quick to reproduce means that inherited characteristics are passed onto future generations much more quickly, so the time taken for the population to adapt to its environment is reduced.
• bacteria reproduce around every 20 to 30 minutes, while humans reproduce every few years, after 20 to 30 years of their life.
• the deeper the rock, the older the fossil.
• the kingdoms animals, plants, fungi and protoctists are eukaryotes whereas bacteria is a prokaryote.
• kingdom: animals

  what all animals have in common are they are:

  • multicellular - they have many many cells
  • heterotrophs - they have to get their energy from other sources
  • they reproduce sexually
• kingdom: plants


  • multicellular - made up many cells
  • autotrophs - they get their energy from the sun, through photosynthesis
• kingdom: fungi

  mushrooms and mould are multicellular, while yeast is unicellular. multicellular organisms are made up of hyphae, which form mycelium, the little lines on mushrooms

  fungi cannot photosynthesise, so they are saprotrophs, meaning they feed using saprophytic nutrients.

  process:

  1. fungi secrete digestive enzymes onto food outside of their body
  2. they wait for the enzymes to break down the food
  3. and then absorb all the nutrients.
• kingdom: protoctists


  nearly all protoctists are unicellular, but there is a lot of variety between species.

  most protoctists have nothing to do with humans, but some count as pathogens
• kingdom: bacteria


  • unicellular
  • some species can photosynthesise, most of them feed off other organisms (usually dead).
  • a few can cause disease (e.g. salmonelle)
  • many are healthy