Biological evolution

  • There were 3 conditions for the origin of life
    ⇒ continuous supply of replicators
    ⇒ copying error during replication
    ⇒ system must have required a continuous supply of free energy.
  • Biological evolution started with the formation of pre/protobionts which are non living structures that led to the formation of first living cells from which the more complex cells have evolved.
  • The 2 prebionts are
    Oparin ⇒ coacervates [aggregation of colloidal particles in liquid phase that consists of carbohydrates, proteins, lipids and nucleic acids surrounded by a non-biological membranes
    Sydney Fox ⇒ Micro spheres [Microscopic membrane bound spheres formed when protenoids are boiled in water and allowed to cool. Protenoids are produced by dehydration synthesis of amino acids at 180°C]
  • Oldest known fossil ⇒ Stromatollites [sheet formed over sedimentary rocks which contained a species of Blue green Algae, called Archaeospheroides barbetonensis].
  • Evolution of modes of Nutrition
    (Photo auto trophs) - Eg. Cyanobacteria
  • As the number of photoautotrophs increased, O2 was released in the sea and atmosphere which is termed as O2 revolution.
  • As O2 accumulated in atmosphere, the UV light changed some of the O2 into Ozone.
    2O2 + O2 → 2O3
  • Origin of Eukaryotes is of two types
    ⇒ Symbiosis [Margulis]
    ⇒ Origin by Invagination
  • Symbiotic origin :
    ⇒ Predator host cell  +  aerobic bacteria  ⇒  Eukaryotic animal cell
                              [Contributing Mitochondria]
    ⇒ Predator host cell + aerobic bacteria + cyanobacteria  ⇒ Eukaryotic plant cell.
                                     [mitochondria]      [chloroplast]
  • Three domains of life [Carl Woese]
    ⇒ Eubacteria
    ⇒ Archae
    ⇒ Eucarya
  • Finally, it is concluded that the life originated from ocean.
    ⇒ Evidences for organic Evolution
  • The study of fossils is called as Palaeontology.
    ⇒ Leonardo da Vinci [The Father of Palaeontology]
    ⇒ George Cuvier [The Founder of modern Palaeontology]
  • The fossils of spores, Pollen grains and other microscopic structures are called micro fossils (or) Palyno fossils.
  • Age of the fossils can be determined by following methods
    ⇒ Clock of the rock method / Radioactive clock
    ⇒ Radioactive carbon method
    ⇒ Potassium - argon method
  • The first geological time scale was developed by Gioranni Avdesina. The history of the earth has been divided into a number of major divisions called eras, which are sub divided into periods. The modern periods are further divided into epochs.
  • The fossil record contains some transitional link forms called missing links [also called as connecting links].
    Eg. Archaeopteryx [connecting link between birds and reptiles]
  • Evolution of Vertebrates :
  • Evolution of horse :
    Eohippus [renamed as Hyracotherium]
    Mesohippus [Intermediate horse]
    Merychippus [ruminating horse]
    Pliohippus [first, one toed horse]
    Equus [modern horse]

Watch this video for the topic from 1:18 to 12:40

Disclaimer: Compete.etutor.co may from time to time provide links to third party Internet sites under their respective fair use policy and it may from time to time provide materials from such third parties on this website. These third party sites and any third party materials are provided for viewers convenience and for non-commercial educational purpose only. Compete does not operate or control in any respect any information, products or services available on these third party sites. Compete.etutor.co makes no representations whatsoever concerning the content of these sites and the fact that compete.etutor.co has provided a link to such sites is NOT an endorsement, authorization, sponsorship, or affiliation by compete.etutor.co with respect to such sites, its services, the products displayed, its owners, or its providers.