The document discusses the origin of the universe, life, and evolution of organisms. It describes two hypotheses for the origin of the universe - the Big Bang theory and Nebular hypothesis. It outlines how life originated from inorganic substances around 3.5 billion years ago, as evidenced by the Miller-Urey experiment. It also discusses homologous organs, analogous organs, vestigial organs, and evidence for evolution such as Archaeopteryx.

1. Facilat
BIOLOGICAL
EVOLUTION
-ANNUJA ANANDARADJE

2. The origin of universe
 The universe is made up of matter and
energy.
 There exists two hypothesis: 1) big bang
2) nebular
 These two explain the origin of the earth.
 Big bang : universe formation by big
explosion.
 Nebular: universe formation by
condensation of gaseous clouds.

3. Big bang theory

4. Nebular hypothesis

5. Origin of life
 Life originated 3.5 billion years ago.
 The first scientific account of origin of life was
given by AL OPARIN in his book ‘ORIGIN OF
LIFE’.
 Primitive atmosphere contained
HYDROGEN,WATER VAPOUR, METHANE ,
AMMONIA. In it o2 and o3 were absent. Thus it
was believed that life originated from
inorganic substances by a series of complex
reactions.

6. Cont.,,
 Hydrogen atoms were the most abundant and
most reactive in the primitive atmosphere.
 First, these combined with all available oxygen
atoms to form water & leaving no free oxygen
atoms.
 Thus primitive atmosphere was ‘REDUCING’
unlike the present ‘OXIDISING’ atmosphere.
 This was supported by MILLER &UREY.

7. MILLER UREY
EXPERIMENT
 A mixture of H2O, hydrogen , ammonia and
methane was recycled through an
apparatus and the organic compounds and
amino acids were obtained.

8. Miller’s experiment

9. Organs and evolution
 Homologous organs
 Analogous organs
 Vestigial organs

10. Homologous organs
 Organs that are similar in basic structure
and origin but dissimilar in function are
called homologous organs.
 Eg : wings of bat, wings of birds, human
hand, front foot of horse,,,
 Homologous organs show divergent
evolution.

11. Homologous organs

12. Analogous organs
 The organs that are similar in function and
shape but dissimilar in origin are called
analogous organs.
 Eg : wings of birds, insects,,,
 Analogous organs show convergent
evolution.

13. Analogous organs

14. Vestigial organs
 These are non-functional organs that were
functional earlier.
 Human body has been described to
possess about 90 vestigial organs.
 Eg: muscles of ear pinnae,
canine teeth,
body hairs,
vermiform appendix,,,

15. Vestigial organs

16. Atavism
 It is the sudden reappearance of ancestral
features.
 (i.e) appearance of thick body hairs ,
canines, extra nipples,,

17. Atavism

18. Evidences from evolutionary link
organism Connecting link
virus Living & non living
euglena Plants & animals.
Peripatus Annelida & arthropoda
Neopilina Annelida & mollusca
Dipnoi ( lung fish ) Pisces & amphibia
Archaeopteryx Reptiles & aves
Protothera Reptiles and mammals

19. Theories of evolution
 Lamarckism : Jean Baptiste Lamarck
 Darwinism : Charles Darwin
 Mutation theory : Hugo de Vries proposed
the theory while working on Oenothera
lamarckiana.

20. Note
 Devonian period : age of fishes
 Mesozoic era : age of reptiles
 Cenozoic era : age of mammals.

21. MCQ
1. Which one of the following is the post-
zygotic isolating mechanism?
a. Behavioral isolation
b. Seasonal isolation
c. Fertilization failure
d. Hybrid sterility

22. The phenomena of genetic drift is
most likely to occur in population
that is
a. Small and inbred
b. Undergoing gene flow
c. Allopatric
d. Large and panmictic

23. In vertebrate evolution, reptiles
were able to move completely on
land due to
a. Their scales
b. The amniotic egg
c. Their increase in size
d. The availability of food

24. In zoos, lions ,tigers mate and produce
viable offspring called tigons and ligers.
Hybrids were never recorded in Asia,
however, where their ranges once
overlapped. Hybrids were probably not
produced because of
a. Behavioral isolation
b. Gametic mortality
c. Hybrid infertility
d. Mechanical isolation.

25. Assume that an animal generates heat at a rate
proportional to its volume and can radiate heat at
a rate proportional to its body surface area/ which
of these animals would be the best at maintaining
its body temperature in a cold climate?
a. Mouse
b. Bear
c. Rabbit
d. Fox.

26. well over 90% of all species ever existed are
extinct today. This shows that,
a. Evolution in inefficient
b. Evolution does not take long term advantage
into account.
c. Evolution in inevitable
d. A very long time has passed since life
began on earth.

27. In allopatric speciation,
a. Populations occupy the same habitat and
there is reduction in gene flow
b. Populations occupy the same habitat and
there is normal gene flow
c. Populations occupy a different habitat
and there is reduction in gene flow
d. Populations occupy a different habitat and
there is normal gene flow.

28. Fossils of marsupial lions were discovered
recently in australia. The fact that such
lions existed points to
a. Convergent evolution
b. Divergent evolution
c. Neutral evolution
d. Reverse evolution

29.  Thank you.