29. EVOLUTION
ion is an orderlychange from one form to another.
utionary Biology is the study of evolutionary history of lifeforms.
ORIGIN OF LIFE
&
Bang Theory states that universe originated about 20 5. Theory of chemical evolution: Proposed by Oparin
on years ago by a singular huge cxplosion. Haldane. It states that, the first form of life was originated
molecules such as
carth was formed about 4.5 billion years ag0. from non-living inorganic & organic
acids etc. i.e.
ie was no atmospBhere on carly earth. Water vapour, CH4, CH4, NH3, H)0, sugars, proteins, nucleic
& NH released from molten mass coverod the surface. "Abiogenesis first, but biogenesis ever since".
UV rays from the sun broke up water into H; and O2. Urey-Miller experiment
encombined with NH, & CHato forn water, CO; ctc. Harold Urey & Electrodes
0/0ne layer was formed. As it coolcd, the water vapour Stanley Miller
IN rain to form oceans. To vacuum
experimentally pump
appeared almost four billionyears ago. proved theory of -Spark
CH, discharge
EORES OF ORIGIN OF LIFE chemical NH.
H,O
Gases
ineory of spontaneous generation (Abiogenesis): It evolution. They 11,
+Water out
les that, life came out of decaying and rotting matter created a
Condenser
Sraw, Imud etc. condition like that
-Water in
ouis Pasteur disproved this theory. He demonstrated of primitive earth
Waler droplets
lite comes only from pre-existing life. (i.e. high
showed that life did not come from killed yeast in a temperature, Boiling water
Waler containing
organic compounds
d pre-sterilized flask. But in an opened flask, life volcanic storms, iguid water in trap
erobes) appeared. reducing atmosphere with CH4, NH,, H;0, H2 etc).
genesis:Proposed by Francisco Redi, Spallanzani & They made electric discharge in a closcd flask containing
i ouis Pasteur. It states that, life originates from pre CH4, NH3, HT and water vapour at 800° C. As a result, Some
ting life. But it does not explain origin of first life. amino acids are formed.
smic theory (Theory of Panspermia): It states that, In similar experiments, others observed formation of
units of life (spores) were transferred to different sugars, nitrogen bases, pigment and fats.
nets including earth. First non-cellular forms of life originated 3 billion years ago.
heory of special creation: It states that, living & non They were self-replicating metabolic capsule containing
ing was created by some supernatural power (God). RNA,proteins, Polysaccharides etc.
EVIDENGES FOR EVOLUTION
teontologica! similarity in structure and origin but different functions.
utology is the study of fossils. This phenomenon is called Homology.
s are remnants of life forms found in rocks (earth crust). E.g. Human hand, Whale's flippers, Bat's wing &Cheetah's
sils are written documents of evolution. foot. These forelimbs have different functions but similar
Sgnificance of fossils: anatomical structures such as bones (e.g. humerus. radis.
Instudy phylogeny(evolutionary history or race history). ulna, carpals, metacarpals & phalanges).
". Horse evolution. Homology is also seen in heart. brain etc.
!o study the connecting link between two groups of Homology in plants: Eg. Thorns of Bougar,les
ganisms. E.g. Archaeopteryx. tendrils of Cucurbita
lo study about extinct animnals. E.g. Dinosaurs. The origin of homologous organs l: ¿ Dirpet
study about geological period by analysing fossils in evolution. It is the evolution by :retned peces
lferent sedimentary rock layers. The study showed that become less similar to surie : aT t met
forms varied over time and certain life forms are environmental condition.
F0572 e
stricted to certain geological time spans. - Homology indicates commr
Morphological &AnatomicalL'evidences
5arative anatomy and morphology shows that different These are the orgar.: 2I KIT Tun mr ái
rms of animals have some common structural features. This structure & or:: ATANNL
explaincd as follows: Wings of insecIS . T A
of birds mc r
Homologous organs Eyes of Ocsap a rar m
tlomologous organs are the organs having fundamental from eobrvat trun
ion is an orderlychange from one form to another.
utionary Biology is the study of evolutionary history of lifeforms.
ORIGIN OF LIFE
&
Bang Theory states that universe originated about 20 5. Theory of chemical evolution: Proposed by Oparin
on years ago by a singular huge cxplosion. Haldane. It states that, the first form of life was originated
molecules such as
carth was formed about 4.5 billion years ag0. from non-living inorganic & organic
acids etc. i.e.
ie was no atmospBhere on carly earth. Water vapour, CH4, CH4, NH3, H)0, sugars, proteins, nucleic
& NH released from molten mass coverod the surface. "Abiogenesis first, but biogenesis ever since".
UV rays from the sun broke up water into H; and O2. Urey-Miller experiment
encombined with NH, & CHato forn water, CO; ctc. Harold Urey & Electrodes
0/0ne layer was formed. As it coolcd, the water vapour Stanley Miller
IN rain to form oceans. To vacuum
experimentally pump
appeared almost four billionyears ago. proved theory of -Spark
CH, discharge
EORES OF ORIGIN OF LIFE chemical NH.
H,O
Gases
ineory of spontaneous generation (Abiogenesis): It evolution. They 11,
+Water out
les that, life came out of decaying and rotting matter created a
Condenser
Sraw, Imud etc. condition like that
-Water in
ouis Pasteur disproved this theory. He demonstrated of primitive earth
Waler droplets
lite comes only from pre-existing life. (i.e. high
showed that life did not come from killed yeast in a temperature, Boiling water
Waler containing
organic compounds
d pre-sterilized flask. But in an opened flask, life volcanic storms, iguid water in trap
erobes) appeared. reducing atmosphere with CH4, NH,, H;0, H2 etc).
genesis:Proposed by Francisco Redi, Spallanzani & They made electric discharge in a closcd flask containing
i ouis Pasteur. It states that, life originates from pre CH4, NH3, HT and water vapour at 800° C. As a result, Some
ting life. But it does not explain origin of first life. amino acids are formed.
smic theory (Theory of Panspermia): It states that, In similar experiments, others observed formation of
units of life (spores) were transferred to different sugars, nitrogen bases, pigment and fats.
nets including earth. First non-cellular forms of life originated 3 billion years ago.
heory of special creation: It states that, living & non They were self-replicating metabolic capsule containing
ing was created by some supernatural power (God). RNA,proteins, Polysaccharides etc.
EVIDENGES FOR EVOLUTION
teontologica! similarity in structure and origin but different functions.
utology is the study of fossils. This phenomenon is called Homology.
s are remnants of life forms found in rocks (earth crust). E.g. Human hand, Whale's flippers, Bat's wing &Cheetah's
sils are written documents of evolution. foot. These forelimbs have different functions but similar
Sgnificance of fossils: anatomical structures such as bones (e.g. humerus. radis.
Instudy phylogeny(evolutionary history or race history). ulna, carpals, metacarpals & phalanges).
". Horse evolution. Homology is also seen in heart. brain etc.
!o study the connecting link between two groups of Homology in plants: Eg. Thorns of Bougar,les
ganisms. E.g. Archaeopteryx. tendrils of Cucurbita
lo study about extinct animnals. E.g. Dinosaurs. The origin of homologous organs l: ¿ Dirpet
study about geological period by analysing fossils in evolution. It is the evolution by :retned peces
lferent sedimentary rock layers. The study showed that become less similar to surie : aT t met
forms varied over time and certain life forms are environmental condition.
F0572 e
stricted to certain geological time spans. - Homology indicates commr
Morphological &AnatomicalL'evidences
5arative anatomy and morphology shows that different These are the orgar.: 2I KIT Tun mr ái
rms of animals have some common structural features. This structure & or:: ATANNL
explaincd as follows: Wings of insecIS . T A
of birds mc r
Homologous organs Eyes of Ocsap a rar m
tlomologous organs are the organs having fundamental from eobrvat trun
