Evolution

Lesson 1

-Fossils: any evidence of once-living organisms from the distant past.

-Fossil record→ is not complete because not everything turn into fossils.

  • soft-bodied organisms from the distantganisms will be less-likely to be made fossils
  • hard-bodied organisms will more likely be fossils.

-water make the best environment for fossil formations→water brings sediments and minerals.

-Stratigraphy: analysing rock sequences in strata(rock layers). which leads to the Geological Timescale, scientists naming different periods of time.

  • the oldest layer of rocks are the ones that are deep down→the Law of Superposition.
  • the order from oldest to younges: A, B, E, C, D. →E did not went through C.

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  • Different kinds of Fossils
    • Indirect fossils are traces, imprints, or casts(chemicals fill an org and harden into quartz of limestone rock) of an organisms
    • Original fossils are the direct preserved remains of the organism.
    • replacement fossils are fossils that are replaced by the sediments; minerals have slowly replaced the orginal material during decay
    • index fossils are fossils that shows general ages(relative dating) of the rock layers when they occur.
    • Carbon film fossils is an outline of a organisms; it’s found in any rock when organic material is compressed, leaving only a carbon residue or film.

  -some examples of fossils: 1. Ammonite 2. trilobite 3. imprints

  • Fossil Formation

  -fossils form when an organism dies and:

  • it is quickly covered in sediments
  • no other creature can eat it
  • no oxygen or micro-organisms get in to cause decay

  -fossils can form in:

  • river, sea, lake bed.
  • swamps
  • some specials such as amber, tar pits, dry air of deserts, frozen environments
  • fossils form in sedimentary rock. (Igneous and metamorphic rock are subject to heat which destroys any fossil.)
  • fossils are discovered when old sedimentary rock is pushed up from underground through faultss or folds. weathering and erosion expose the fossil.

Lesson 2

  • Learning Objectives

  -define relative dating of fossils

  • define index fossils and outline how they are used in relative dating

  -define absolute dating of fossils

  • describe radioactive dating
    • Relative Dating

  -technique that compares one fossil with another to determine which is older and which is younger.

  -does not determine the actual age of the fossil.

  

  1. Rock layers
  2. fossils are found in sedimentary rocks, which forms layers called Strata.
  3. the Law of Superposition →The deeper the layer, the older the rock and the fossil. Hence, fossils found in deeper layers are older than those in higher layers
  4. fossils in the same layer are the same age

  

  1. Index fossils
  2. Index fossils are used to compare the age of rock layers at different locations
  3. In order to used the index fossil, the organism must:

     1. have lived for a short period of time 2. be found in many locations 3. have been abundant 4. easy to identify

  • examples of index fossils: trilobites, ammonites
    • Absolute Dating

  -any method of determining the actual age of a fossil; many differ ways, the most helpful→radioactive dating

  

  1. Radioactive Dating/Carbon Dating
  2. Rocks contain some radioactive elements that emit radiation and decay into a differ element gradually
  3. the rate of decay is known to scientists
  4. by measuring the proportion of the initial element and final element, scientists can work out the age of a rock

  How?

  • measuring the percentage of carbon 14 and Nitrogen; carbon 14 to nitrogen; C-14 was formed when N-14 was hit by the neutrons produced by the cosmic rays.
  • C-14 and C-12 ratio in an organisms is the same with the ratio in the atmosphere since the organisms is consuming food(palnts rake food from atmosphere, organisms consume plants).
  • but when a organisms is dead, it stop consuming food, the C-14 in its body will begain to decay into N-14.
  • Isotopes: same elements ith differ numbers of neutrons→unstable.
  • Half Life: time taken for 50% of the isotope to decay; Carbon=5730 years.

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-If all known fossils in the world are put into chronological order, we have what is called the Fossil Record.

Lesson 4

  • Evidence of Evolution
    • Biochemistry

    -the study of chemicals that make up living organisms

    -it is notable that all living organisms are made up of sthe same chemicals

    -Proteins→it has same functions in differ organisms.

    -DNA→the sequence of nucleotides * Comparative anatomy

      -the comparison of structures in differ living things, looking for similarities

      -differ living thins with similar structures that suggests a common ancestors.

      -organs have similar function but different structures

      →Pentadactyl limb * humans, monkeys, frogs, lizards, bats, cats and whales all have 5-digits at the end of their forelimbs.

  • Biogeography

    -Alfred Wallace noted that the bird