B6 - Life on Earth, Past, Present and Future

• Process of natural selection:

  1. Within any species, there is variation so they are not all the same
  2. The organisms compete for resources but there is not enough to go around
  3. Some individuals have features which better help them so survive
  4. The better suited individuals are more likely to pass on the feature/gene
  5. Most of the next generation have the useful feature
• Natural Selection - The process by which populations evolve over time as a result of differential survival and reproduction of individuals due to differences in phenotype.
• Human Evolution - Over millions of years, humans developed larger brains, smaller jaws with fewer teeth, bipedalism and opposable thumbs. These changes allowed us to hunt, gather and make tools.
• Selective breeding process:

  1. There is variation within a species
  2. Humans select characteristics that benefit them the most
  3. Humans breed the organisms with the desired characteristics
  4. Humans select the offspring with the desired characteristics and breed them repeating the process over many generations
  5. The vast majority of the offspring have the desired characteristic
• Selective breeding - A method used by humans to produce animals or plants with desirable traits through controlled mating.
• Classification - The process of grouping organisms into groups based on similarities and differences.
• Classification:

  A) Eukaryotes

  B) Archaea

  C) Bacteria

  D) Bacteria

  E) Archaea

  F) Protists

  G) Fungi

  
• Charles Darwin - he proposed the theory of evolution by natural selection and made it world-spread.
• Homologous Structures - Similar structures found in different species due to common ancestry.
• Fossils are the remains of organisms from the past that are found in rocks.
• Fossils are proof of evolution of organisms by matching the skeletal and DNA remains with modern animals
• Natural Selection - The process where individuals with advantageous traits are more likely to survive and reproduce than those without such traits.
• Benefits of using fossils as proof of evolution:

  • Can compare living and extinct organisms
  • Can compare fossils throughout time
  • Fossil records tell us when and where organisms lived
• Problems with using fossils as proof of evolution:

  • Some fossils have been lost (eroded)
  • Limited number of fossils or organisms
  • Only hard bodies are fossilised - no soft tissue
• A transitional fossil has features of older and new organism and provides a link in evolution
• The closer two species are genetically, the more recent they diverged from a common ancestor
• Carl linneaus: 1735-1778, developed the binomial (two name) system of naming organisms
• Binomial Nomenclature: A standardized way of giving every known plant and animal its own unique scientific name based on characteristics that distinguish it from other species
• Speciation: the formation of new and distinct species in the course of evolution.
• Process of speciation:

  1. There is variation within a species
  2. The species become split by a physcial or biological barrier so become isolated
  3. Natural selection occurs to both population due to the new, different conditions of the new environment
  4. Overtime, the two populations become so different in phenotype and genotype they cannot breed together so become different species
• Sympatric Speciation: when environmental factors cause reproductive isolation without physical separation
• Allopatric Speciation: when geographical barriers prevent interbreeding between populations leading to speciation
• Habitat loss: destruction of natural habitats through human activities such as deforestation, urbanisation, agriculture etc. This leads to extinction of many species
• Extinction: The process whereby all individuals of a particular species die off
• Pollution: release of toxic substances into an environment that can harm living organisms
• The benefits of biodiversity:

  • Interdependance
  • Range of different resources
  • Less threat of disease wiping out ecosystems
  • Sustains nutrient cycle
  • pollination
  • Draft (working) animals
  • Medicine
  • Fibres (clothing)
  • Fuel
  • Range in diet
• Biodiversity is important because it provides us with a range of products and services which we depend upon for our survival and wellbeing.
• The different levels of protection for biodiversity:

  • Global level - restrictions of CO2 emissions and hunting of animals
  • Environmental level - National parks, green belt areas
  • Species level - Protecting endangered species, breeding programs
  • Genetic level - Seed banks
• Threats to biodiversity -

  • Habitat loss - Deforestation in forests
  • Invasive species - Grey squirrels, Came toads
  • Population growth of humans - Buildings of cities/moterways/roads creating impact on habitats by restricting that area
  • Pollution - Plastic pollution, oil spills, sewage
  • Overexploitation - overfishing/poaching/deforestation which means species cannot reproduce enough so species decrease