10) Classification and evolution

• Taxonomic system:

  Domain

  Kingdom

  Phylum

  Class

  Order

  Family

  Genum

  Species
• Binomial naming:

  Genus - upper case first letter

  Species - all lower case
• kingdom system:

  Plantae

  Animalia

  Prokaryote

  Protoctists

  Fungi
• Prokaryotae

  • unicellular
  • no nucleus
  • Autotrophic, heterotrophic, or parasitic
• Protocista:

  • unicellular
  • nucleus
  • Autotrophic, heterotrophic, or parasitic
• autotrophic - nutrients acquired by photosynthesis
• heterotrophic - eats other organisms
• parasitic - living as a parasite on another organism
• Fungi:

  • unicellular or multicellular
  • a nucleus
  • cell wall made of chitin
  • no chloroplast or chlorophyll
  • Saprophytic, absorb dissolved organic nutrients from dead matter
  • store food as glycogen
• Plantae:

  • eukaryotic - have a nucleus
  • multicellular
  • contain chlorophyll
  • stores food as starch
  • Autotrophic (photosynthesis)
• Animalia:

  • multicellular
  • nucleus
  • no chloroplasts
  • Heterotrophic
  • food stored as glycogen
• The three domains:

  • Bacteria
  • Archaea
  • Eukarya
• Domain Bacteria:

  • contains kingdom eubacteria
  • Prokaryotic unicellular organisms
• Domain Archaea:

  • Contains the kingdom Archaebacteria only
  • Prokaryotic unicellular organisms.
  • Have histones so gene and protein synthesis is more similar to Eukarya than Bacteria.
  • No peptidogylcan in their cell walls.
  • Different cell membranes that contain fatty acids bound to glycerol by ether linkages.
  • Have a more complex form of RNA polymerase than Bacteria.
• Domain Eukarya:

  • Contains four kingdoms from the five kingdom system: Animalia, Plantae, Fungi, Protoctista.
  • All have nuclei and membrane-bound organelles.
• Phylogeny:

  • based on evolutionary relationships between organisms and their ancestors, classifying species into groups. It reveals how closely related organisms are.
• Advantages of phylogeny:

  • It produces a continuous tree that doesn't force organisms into specific taxonomic groups where they don't quite fit.
  • There is no overlap between the groups produced.
• Theory of evolution by natural selection

  • Darwin and Wallace
  • They suggested that organisms best suited to their environment are more likely to survive, reproduce, and pass on their advantageous characteristics to their offspring.
• Evidence for evolution from the fossil record:

  • Palaeontology, the study of life's history as recorded in fossils, involves examining organisms preserved in rock layers.
  • Simple bacteria and algae fossils are found in the oldest rocks, progressing to more complex vertebrates in newer rocks.
• why the fossil record is incomplete:

  • Many organisms decompose before they can fossilise.
  • Fossilisation is uncommon, and requires specific conditions for an organism to be preserved.
  • Over time, many fossils have been lost due to erosion or geological processes.
  • Many organisms have not yet been discovered.
  • Certain organisms, especially those with soft bodies, are less likely to fossilise, leading to gaps in the record.
• comparative anatomy - examines the anatomical structures of different living species to find similarities and differences.
• Homologous structures - physical features in different species that have a similar underlying structure but may serve different functions. Likely to have evolved from common ancestors. They are evidence of divergent evolution, have common ancestors develop different trait or characteristics o adapt to changing environmental conditions and needs.
• Comparative biochemistry - the study of similarities and differences in proteins and molecules that control life processes.
• Comparative biochemistry:

  • Ribosomal RNA - This molecule is integral to protein synthesis so it changes slowly, making it useful for showing connections between species that diverged long ago.
  • Nuclear, mitochondrial or chloroplast DNA - Species that are more closely related will have more similar DNA sequences.
  • Messenger RNA - Base sequences of mRNA are complementary to DNA so can assess DNA diversity.
  • Amino acid - If they are closely related evolutionarily, two species have more similar amino acid sequences because they are determined by mRNA and DNA.
• adaptation - characteristics that increase an organisms chance of survival and reproduction in its environment
• types of adaptation:

  anatomical - physical features

  behavioural - way an organism acts

  physiological - processes that take place inside an organism
• anatomical adaptations:

  body covering - hair, scale, spines feathers and shells

  camouflage - outer colour allows it to blend in with its environment, making it harder for predators to spot

  teeth - shape and type of teeth relate to its diet. e.g carnivores such as tigers, have sharp canines to kill prey

  mimicry - copying another animals appearance or sounds allows harmless organisms to fool predators into thinking its dangerous
• anatomical example: marram grass

  • commonly found in sand dunes
  • xerophyte
  • curled leaves
  • hairs
  • stomata sunken in pits
  • thick waxy cuticle
• behavioural adaptations:

  survival behaviours - opossum plays dead

  courtship - to attract a mate e.g scorpions perform a dance to attract a partner, to increase chance of reproduction

  seasonal behaviours - enable organisms to cope with changes in environment e.g hibernation and migration

  can be innate or learned
• physiological adaptations:

  poison production - reptiles produce venom to kill its prey and many plants produce poisons in their leaves

  antibiotic production - some bacteria produce antibiotics to kill other species of bacteria in the surrounding area

  water holding - the water holding frog can store water in its body, this allows it to survive in the desert.
• anatomical adaptations provide evidence for convergent evolution

  • convergent evolution takes place when unrelated species begin to share similar traits
  • these similarities evolve because organisms adapt to similar environment
• anatomical adaptations provide evidence for convergent evolution

  examples:

  • marsupial and placental mice - both small, agile climbers that live in dense cover and forage at night
  • flying phalanges and flying squirrel - both are gliders that eat insects and plants. There skin is stretched to provide a large surface area
• marsupial - species in each continent resemble eachother as they have adapted to the niches
• placental - placenta connected to the embryo of its mothers
• interspecific variation - the differences between different species
• instraspecific - the differences between individuals of the same species
• continuous variation - normally quantitative, any feature that can be measured and controlled by both genes and environment

  e.g height, length of leaves
• discontinuous variation - normally qualitative, ant feature that cant be measured controlled by genes

  e.g blood group and eye colour
• antibiotic resistance

  • mrsa has developed resistance to many antibiotics
  • bacteria reproduce very rapidly and so evolve in a short time
  • when they replicate their dna is altered and this results in bacteria dying
  • when the bacteria was exposed the resistance individuals survived and reproduced, passing on their allele