GEN BIO 2

• Evolution - study of history of life forms on earth.
• Evolution - orderly change from one form to another
• Which Theory states that the universe orginated about 20 billion years ago by a singular huge explosion?

  Big Bang Theory
• The earth was formed about 4.5 billion years ago
• Is there atmosphere on early earth?

  No
• Wager vapor, CH4 , C02 , and NH3 released from molten mass covered the surface.
• The UV rays from the sun broke up water into H2 and O2
• Oxygen combined with NH3 & CH4 to form water, C02 etc.
• life appeared almost four billion years ago
• THEORIES OF ORIGIN OF LIFE (ABPCC)

  • Theory of Abiogenesis
  • Theory of Biogenesis
  • Theory of Panspermia
  • Theory of Creationism
  • Theory of Chemical Evolution
• What is the other term for Theory of Abiogenesis?

  Theory of Spontaneous Generation
• Theory of Abiogenesis - It states that, life came out of decaying and rotting matter like straw, mud etc.
• Who disporved Abiogenesis theory?

  Louis Pasteur
• Louis Pasteur - He demonstrated that life comes only from pre-existing life.
• Louis Pasteur - He showed that life did not come from killed yeast in a closed pre-sterilized flask. But in an opened flask, life (microbes) appeared.
• Theory of Biogenesis - It states that, life originates from pre-existing life. But it does not explain origin of first life.
• Who proposed the Theory of Biogenesis

  A) Francisco Redi

  B) Spallanzani

  C) Louis Pasteur

  
• Theory of Panspermia - It states that, the units of life (spores) were transferred to different planets including earth.
• What is the other term for theory of panspermia?

  Cosmic Theory
• What is the other term for theory of creationism?

  Theory of Special Creation
• Theory of Creationism - it states that living and non-living was created by some supernatural power (God).
• Who proposed the Theory of Chemical Evolution?

  .

  A) Haldane

  B) Oparin

  
• Theory of Chemical Evolution - It states that, the first form of life was originated from non-living inorganic and organic molecules such as CH4, NH3, H20, sugars, proteins, nucleic acids etc.

  i.e. "Abiogenesis first, but biogenesis

  ever since".
• Who proved the theory of chemical evolution?

  .

  A) Stanley L. Miller

  B) Harold C. Urey

  
• Urey-Miller Experiment - They created a condition like that of primitive earth (i.e. high temperature, volcanic storms, reducing atmosphere with CH

  NH3, H20, H2 etc.). They made electric discharge in a closed flask containing CHV NH 3' H2 and water vapour at 800 deg C. As a result, some amino acids are formed.

  
• THEORIES OF ORIGIN OF LIFE - The first non-cellular forms of life originated 3 billion years ago. They were self replicating metabolic capsule containing macromolecules like proteins, Polysaccharides etc.

  
• EVIDENCES FOR EVOLUTION

  Paleontological evidences

  Morphological and Anatomical evidences

  Biogeographical evidences (Adaptive Radiation)

  Biochemical evidences

  Embryological evidences

  Evidences for evolution by natural selection
• Palaeontology is the study of fossils.
• Fossils are remnants of life forms found in

  rocks (earth crust).
• Fossils are written documents of evolution.
• Palaeontological Evidences - To study phylogeny (evolutionary history or race history). E.g. Horse evolution.

  
• Palaeontological Evidences - To study the connecting link between two groups of organisms. E.g. Archaeopteryx. To study about extinct animals. E.g. Dinosaurs.

  
• Palaeontological Evidences - To study about geological period by analysing fossils in sedimentary rock layers. The study showed that life forms varied over time and certain life forms are

  to certain geological time spans.

  
• Morphological & Anatomical Evidences -Comparative anatomy and morphology shows that different forms of animals have some common structural features.

  (homology & analogy)
• Homologous organs & Homology (phenomenon) - Same Structure, Different function

  
• Analogous organs & Analogy (phenomenon) - Same Function, Different structure

  
• Homology is also seen in heart, brain, plant (Thorns & tendrils of boungainvillea & cucurbita)

  
• The Origin of homologous organs is due to Divergent evolution.
• Divergent evolution is the evolution by which related species become less similar to survive and adapt in different environmental condition.

  
• Analogy is also see in wings of insects and birds, eyes of octopus and human, flipper of penguins and dolphins, kamote and potato, trachea of insets and lungs of vertebrates