biology paper 2 variation and evolution

    Cards (33)

    • How fossils form
      1. Parts of organisms not decaying due to absence of decay conditions
      2. Parts of organisms slowly replaced by minerals during decay
      3. Preserved traces of organisms like footprints or spaces where roots were
    • Fossils
      Remains of organisms from millions of years ago found in rocks
    • Soft-bodied organisms very rarely form fossils
    • Many fossils of early life-forms have been destroyed by changes to rocks in the Earth's crust
    • Scientists cannot be certain how life on earth began due to very few fossils of early forms of life
    • A species is extinct when there are no remaining individuals of that species still alive
    • Species can become extinct due to
      Catastrophic events, environmental changes, competition with new more successful species
    • Extinction can occur due to catastrophic events like an asteroid colliding with the earth
    • Extinction can occur due to environmental changes like changing weather patterns, new diseases, or new predators
    • Extinction can occur if a new more successful species evolves and competes for scarce resources like food or water
    • How bacteria become resistant to antibiotics
      1. Bacteria can reproduce every 30 minutes, allowing for rapid evolution under ideal conditions
      2. Doctors began using antibiotics in the 1940s to treat bacterial diseases
      3. Antibiotics kill bacteria, but certain strains have evolved to be resistant
      4. Mutation can make a bacterium resistant to antibiotics
      5. Antibiotic-resistant bacteria survive and reproduce without competition, leading to the rise of the resistant strain
      6. Resistant strains spread as people are not immune to them and there's no effective treatment
    • Common strain of antibiotic-resistant bacteria
      • Mosa
    • Doctors should not prescribe antibiotics inappropriately, such as for viruses
    • Patients should complete the course of antibiotics to ensure all bacteria are killed and none can survive to form resistant strains
    • We should restrict the use of antibiotics in animals
    • Developing new antibiotics

      Researchers are currently developing new antibiotics, which is time-consuming and expensive
    • New antibiotic-resistant bacteria emerge constantly, making it challenging to combat them
    • There are millions of different species on planet Earth with common characteristics
    • Scientist Carl Linnaeus began to classify species into different categories based on structure and characteristics

      1700s
    • Linnaeus' classification categories
      • Kingdom
      • Phylum
      • Class
      • Order
      • Family
      • Genus
      • Species
    • Linnaeus divided all living organisms into two kingdoms: Animal Kingdom and Plant Kingdom
    • Linnaeus divided each kingdom into smaller categories: Kingdom, Phylum, Class, Order, Family, Genus, Species
    • Mnemonic for Linnaeus' classification system: King Phillip came over for good soup
    • Binomial system: Organisms named by Genus and Species e.g., Equus quagga for a zebra
    • Binomial name for polar bear: Ursus maritimus
    • Classification system based on visible characteristics like body shape or number of toes
    • Advances in biology allow analysis of internal structures and biochemistry like DNA for similarity to other species
    • Three domains in the system
      • Archaea
      • Bacteria
      • Eukaryota
    • Archaea are primitive bacteria often found in extreme conditions
    • True bacteria like those in the human digestive system
    • Eukaryota includes animals, plants, fungi, and protists like amoeba
    • Evolutionary trees show how closely related organisms are and their common ancestors
    • For extinct organisms, scientists use fossils to create evolutionary trees, but fossil records may be incomplete