The document discusses the heterotrophic hypothesis for how life arose on early Earth. It proposes that the first life forms were heterotrophic, obtaining nutrients from the environment. These early aggregates developed membranes and the ability to reproduce, becoming the first living cells. Over time, some heterotrophs evolved the ability to perform photosynthesis, becoming the first autotrophs. The theory of evolution is then discussed, along with evidence from geology, anatomy, embryology, cytology, and biochemistry. Modern evolutionary theory incorporates both Darwin's ideas of variation and natural selection, as well as more recent understanding of the sources of genetic variation.

1. The Theory
of Evolution
06/07/12 cott

3. Evolution
• A process of change
through time
06/07/12 cott

4. (I) Heterotroph Hypothesis
• Is one proposed explanation for how
life arose and evolved on primitive
earth
• According to this hypothesis, the first
life forms were heterotrophic and had
to obtain their nutrients from the
environment
06/07/12 cott

5. (A) Primitive Earth
• Based on assumption
2. Earth was very hot.
3. consisted of inorganic substances
4. Many sources of energy including heat,
lightning, solar radiation(x-rays and U.V. rays),
5. The atmosphere: water vapor, hydrogen,
methane gas, and ammonia.
6. As the earth cooled, water condensed in the
atmosphere and rain fell forming seas
described as “hot, thin soup”
06/07/12 cott

6. (B) Synthesis of Organic Compounds
In the seas:
– Chemical reactions formed inorganic
substances
– Inorganic substances bonded make
organic substances: amino acids and
sugar.
06/07/12 cott

7. (C) Nutrition
• Some of the large, complex molecules
formed groupings or clusters called
aggregates.
• Aggregates developed membranes
• Aggregates absorbed organic molecules
• Aggregates carry out first heterotrophic
nutrition.
06/07/12 cott

8. (D) Reproduction
1. In time, as these aggregates became more
complex and highly organized, they
developed the ability to reproduce
2. At the point where the ability to reproduce
had evolved, the aggregates were
considered to be living cells
06/07/12 cott

9. (E) Heterotroph to Autotroph
1. Early heterotrophs carry out fermentation.
2. Fermentation adds carbon dioxide to the
atmosphere
3. Heterotrophs develop the capacity to use
carbon dioxide from the atmosphere to form
organic compounds (photosynthesis)
4. These organisms were the first autotrophs.
06/07/12 cott

10. (F) Anaerobes to Aerobes
1. Photosynthesis adds free oxygen to the
atmosphere.
2. Over time, the capacity to use oxygen in
respiration (aerobic) evolved in both autotrophs
and heterotrophs
3. Present day organisms may be heterotrophic or
autotrophic >>>>>> aerobic or anaerobic.
06/07/12 cott

11. II Theory of Evolution
1. Suggests that existing forms of life
on earth have evolved from earlier
forms over long periods of time
2. Evolution accounts
– differences in structures
– differences in function, and behavior
– changes that occur in populations
06/07/12 cott

12. 06/07/12 cott

13. Evidence of Evolution
• Supports the theory of evolution
• Geologic record
• Comparative Cytology
• Comparative Biochemistry
• Comparative Anatomy
• Comparative Embryology
06/07/12 cott

14. (A) Geologic Record
• Earth’s age: 4.5 to 5 billion years old
(age was determined by radioactive
dating of rocks)
• Fossils- are the remains of traces of
organisms that no longer exist.
Fossils have been preserved in ice,
sedimentary rock, amber, and tar
06/07/12 cott

15. Tyrranosaurus rex
06/07/12 cott

16. (B) Comparative Anatomy
• Evidence supports that
similarities of basic
structures exist between
different organisms
• Homologous structures
are anatomical parts
found in different
organisms in origin and
structure
• The presence of such
homologous structures
suggest that these
organisms have evolved
from a common ancestor cott
06/07/12

17. (B) Comparative Anatomy
Homo sapiens
Paranthropus boisei
06/07/12 cott

18. (C) Comparative Embryology
• A comparison of the
early stages of their
embryonic
development may
show similarities that
suggest a common
ancestor
06/07/12 cott

19. (C) Comparative Embryology
06/07/12 cott

20. (D) Comparative Cytology
1. All living things are made up of cells
2. Cell organelles including the cell
membrane, ribosome's, and
mitochondria are structurally and
functionally similar in most
organisms
06/07/12 cott

21. Mitochondrion DNA and can
replicate
06/07/12 cott

22. 06/07/12 cott

23. (E) Comparative Biochemistry
• All living things contain similar
biochemical compounds
• Examples: structure and function
of DNA, RNA, and proteins
06/07/12 cott

24. (III) Theories of Evolution
• Attempts to explain the similarities
and differences among species.
• Adaptations- features which make a
species better suited to live and
reproduce in its environment.
06/07/12 cott

25. (C) Charles Darwin
06/07/12 cott

26. (C) Darwin’s Ship the HMS Beagle
06/07/12 cott

27. 06/07/12 cott

28. (C) Darwin
• Charles Darwin devised a theory of evolution
based on variation and natural selection as seen
in the Galapagos islands.
• Included in hid theory were five main ideas:
1. Overpopulation
2. Competition
3. Survival of the Fittest
4. Reproduction
5. Speciation
06/07/12 cott

29. 06/07/12 cott

30. 06/07/12 cott

31. 06/07/12 cott

32. Overpopulation
• Within a population, there
are more offspring produced
in each generation than can
possibly survive
06/07/12 cott

33. Competition
• Natural resources: food, water,
and space available to a
population is limited.
• Many organisms with similar
nutritional requirements, there
must be competition between
them for the resources needed to
survive
06/07/12 cott

34. Survival of the Fittest
• Variations among
members of a population
make some of them better
adapted to the
environment than others
• It is generally the best-
adapted individuals that
will survive
• The environment is the
agent of natural selection
determining which
species will survive
06/07/12 cott

35. Reproduction
• Individuals that survive and
then reproduce transmit these
variations to their offspring
06/07/12 cott

36. Speciation
• The development of a new species
occurs as variations or adaptations
accumulate in a population over
many generations
• Ex: caveman  present man
06/07/12 cott

37. What
mechanisms
led to this
speciation?
06/07/12 cott

38. Explain the following: Two islands with similar environments located in
different oceans, are populated by organisms that resemble nearby mainland
organisms more than they resemble each other.
06/07/12 cott

39. (IV) Modern Theories of Evolution
• Includes both Darwin’s ideas of
variation and natural selection
and the current knowledge of the
sources of variations.
06/07/12 cott

40. (A) Sources of Variations
• Segregation and the
recombination of genes during
sexual reproduction
• Gene mutation occurs
spontaneously and at random
06/07/12 cott

41. (B) Natural Selection
• Traits which are beneficial to the
survival of an organism in a
particular environment tend to be
retained and passed on, and
therefore, increase in frequency
within a population.
06/07/12 cott

42. Ex: Insects resistant to insecticides
1. Genetic make-up of some insects make them resistant
to the effects of insecticides
2. Before the widespread use of insecticides, this trait was
of no particular survival value
3. With the increased use of insecticides, this trait
developed a very high survival value
4. Therefore, insects with resistance to insecticides
survived and reproduced much more successfully than
those lacking the trait
5. As a result, the frequency of insecticide resistance has
increased greatly in insect populations
06/07/12 cott

43. (C) Geographic Isolation
• Isolation of a population increases the chances
for speciation (the development of a new
species.)
• Separates a small group of organisms from the
main population with its large gene pool
(inheritable traits).
• Geographic isolation is caused by natural
barriers like mountains, large bodies of water,
and deserts.
06/07/12 cott

44. 06/07/12 cott

45. (D) Reproductive Isolation
• If the isolated population becomes so
different from the main population that
members of the two cannot interbreed and
produce fertile offspring, then they have
become two distinct species
06/07/12 cott

46. (V) Time Frame for Evolution
• There are two different theories proposed
by scientists to address the rate of
evolution:
1. Gradualism- proposes that evolutionary
change is slow, gradual, and continuous
2. Punctuated Equilibrium- proposes that
species have long periods of stability
(several million years) interrupted by
geologically brief periods of significant
change during which a new species may
evolve
06/07/12 cott

47. Punctuated
Gradualism
06/07/12 cott
Equilibrium