EVOLUTION OF PLANTS THROUGH AGES

Transcription

1 EVOLUTION OF PLANTS THROUGH AGES B. Sc. III Botany Dr. (Miss) Kalpana R. Datar Assistant Professor DEPARTMENTOF BOTANY WILLINGDON COLLEGE, SANGLI.

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3 The origin of Earth 1.Ultra dense, ultra small primordial unit exploded about 15 billions years ago-big Bang. 2.Our galaxy Akashganga or Milky Way was formed around 10 billion years ago. 3.A cloud made up of dust and gases whirled through the empty space about 6 billion years ago. 4.Thus about 4.6 billion years ago the solar system was born and also our planet The Earth

4 1.The origin of Earth Ga. 2.The Hadean Earth Ga. 3.The Archean Earth Ga. 4. The Proterozoic Earth my. 5. The Palaeozoic Earth my. 6.The Mesozoic Earth my. 7.The Cenozoic Earth Recent.

5 1.The origin of Earth- 2.The Hadean Earth- 3.The Achaean Earth Ga Ga Ga.

6 Big Bang

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8 Earth Moon

9 Volcano

10 The Hadean Earth Ga. Scientists named the Hadean Eon after the Greek god Hades, who ruled the underworld, because during most of the Hadean period the surface of the Earth must have been like our image of Hell...

11 The Hadean Earth Ga. 1.The three layers of earth- core,mantle and crust. 2.The lithosphere the crystallization of the uppermost part of the mantle. 3. The Palaeo-atmosphere-The gases originally trapped,inside the earth were released to form the earths initial atmosphere Hydrogen,Helium and Argon. 4. A secondary atmosphere Methane, ammonia, water vapour, carbon mono and dioxides, hydrogen sulphide, Nitrogen dioxide, and trace elements such as Helium and Neon.

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14 O 2 and C0 2 level- 1.The level of C0 2 was three times more than the level of CO 2 in the present atmosphere. 1.Absence of ozone layer. 2.The photolysis of water vapour and CO 2. 3.The initial levels of O 2. 4.The co- existence of oxidized iron and reduced Uranium in the oldest rock is the best possible evidence of the presence of higher oxygen in the early atmosphere.

15 The Palaeo-Hydrosphere- 1. As a result of intense devolatilization of the mantle, enormous quantities of water vapour accumulated in the palaeo - atmosphere. 2. The oceans are believed to have reached their present volume 2000 my. ago and since then there has not been much of a change. 3. The early seas were probably more acidic because of dissolved CO The impact of meteorites and comets.

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17 Prebiotic Synthesis- 1.The hypothesis of spontaneous generation of life. 2. The chemical evolution hypothesis. 3. The origin of life near hydrothermal vents. 4. Directed Panspermia theory. 5. The evaporation pond model.

18 1.Molecular hydrogen,co, Ammonia, water, and H 2 S - raw materials for the formation of hydrogen cyanide and Acetaldehyde, which are precursors to amino acids - the building blocks of proteins. 2.Cyanoacetylene,Phophorous nitride and water- Nucleic acids the carriers of genetic information. 3.Formaldehyde, formic acid, cyanamide synthesized sugars and lipids-cell membranes. 4.Then the first biological polymer - RNA and DNA came into existence.

19 The Archean Earth Ga. 1. The plate tectonic movements 2.The absence of ozone layer. 3. The first organism must have floated in the early seas. 4.A mutant photosynthetic sulpher bacteria. 5.Anaerobic chemo-autotrops- the Methanogenic bacteria were probably the first to flourish on the earth, Anaerobic photo-autotrophs. 6.Aerobic photo-autotrophs- Cyanobacteria, Prochlorophytes, Stromatolites

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21 1.The capacity to withstand the oxygenic environment was a major step in the organic evolution. 2.The appearance of Oxygen important for biological Synthesis. 3.The formation of the ozone layer. 4.Isua supracrystal - the first terrestrial rock Yeast like Microfossil. 5.Methanogeneic bacteria- used CO 2 as their immediate source of Carbon by a metabolic process which was independent of light.

22 6. An inter mediate group of organism Amphi-anaerobes evolved. 7.Aerobic photo-autotrophs- -Produced oxygen as a by product of photosynthesis.

23 The Late Archaean 1. Morphological, physiological and behavioural diversification of microorganisms 2. Increase in oxygen concentration (free oxygen). 3. A stable aerobic environment became established.

24 REFERENCES Venkatachala,B.S The earliest biosphere- Past of the terrestrial flora. Geophytology 23(1):01-18 Images C8CyFKpFfnQMAgCmSCi2OZ0mJRXJmGkKNRlKIX6Aedw- 86Dl8MNC6gj91cPrLg_1ya9sNXMDazKioSCcLwLIUqkVdEf3R1UXtqtWzKhIJAwCAKZIKLY4R2GqRz_1PbTlMqEglnSYlFcmYaQhHf78Wg_1rKMbyoSCY1 GUohfoB53EWKox_1MAdxaBKhIJD7zoOXww0LoRaiugbJanbXYqEgmCP3VwsuD_1BH9gzZfkWh5YSoSCZr2w1cwNrMqEc5EHCZBCdRH&tbo=u&sa=X&ved=0ahUKEwiSkOL i09tyahwbui8khfnebxoq9c8ihw&biw=1366&bih=662&dpr=1#imgrc=0ydr7ictx4vg0m: &tbm=isch&sa=x&ved=0ahukewj_3ztrydtyahxmpo8khvpmbpqq_auicygc&biw=1366&bih =662 &rlz=1c1chbd_enin761in761&source=lnms&tbm=isch&sa=x&ved=0ahukewjddaay9tyahujr48khth8djyq_auicygc&biw=1366&bih=662#imgrc=2w9nmzl5o3yf8m:

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26 Continued