3. Evolution
• A process of change
through time
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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
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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”
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6. (B) Synthesis of Organic Compounds
In the seas:
– Chemical reactions formed inorganic
substances
– Inorganic substances bonded make
organic substances: amino acids and
sugar.
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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.
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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
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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.
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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.
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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
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13. Evidence of Evolution
• Supports the theory of evolution
• Geologic record
• Comparative Cytology
• Comparative Biochemistry
• Comparative Anatomy
• Comparative Embryology
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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
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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
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18. (C) Comparative Embryology
• A comparison of the
early stages of their
embryonic
development may
show similarities that
suggest a common
ancestor
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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
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23. (E) Comparative Biochemistry
• All living things contain similar
biochemical compounds
• Examples: structure and function
of DNA, RNA, and proteins
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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.
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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
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32. Overpopulation
• Within a population, there
are more offspring produced
in each generation than can
possibly survive
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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
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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
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35. Reproduction
• Individuals that survive and
then reproduce transmit these
variations to their offspring
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36. Speciation
• The development of a new species
occurs as variations or adaptations
accumulate in a population over
many generations
• Ex: caveman present man
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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.
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40. (A) Sources of Variations
• Segregation and the
recombination of genes during
sexual reproduction
• Gene mutation occurs
spontaneously and at random
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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.
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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
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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.
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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
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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
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