Biology 2 /SL Review Book Topic 5.4: Evolution
Name ________________________
Key facts Topic 5.4: Evolution
1. Evolution is the cumulative change in the heritable characteristics of a population.
2. If we accept not only that species can evolve, but that new species may also arise by evolution from
pre-existing ones, then all of life may be seen as unified by its common origins.
3. The variations that are seen within a species are due to different selection pressures operating in
different parts of the world. However, these variations are not such that a new species may be said
to have formed. Different races are an example of this.
4. Homologous structures amongst different species represent evidence for evolution.
5. Homologous structures are structures that have developed from the same part of a common
ancestor but may have different functions today. They show similarity in structure but, not
necessarily, function.
6. Fossils also represent evidence for evolution. Fossils show similarities and differences to organisms
of the present. However, missing links are not present to show a definite change from the fossil to
the present organism.
7. Another piece of evidence for evolution is that breeds of animals that are reared for human use are
clearly related to wild species and in many cases can still interbreed with them.
8. These domesticated breeds have been developed from wild species by selecting desirable traits, and
breeding from them. This is evidence that evolution can proceed rapidly.
9. Populations tend to produce more offspring than the environment can support. The result of this
will be competition with the best adapted individuals surviving. This is the concept of natural
selection or survival of the fittest. The fact that there is variation within a population due to sexual
reproduction allows one organism to out-compete another.
10. Greater survival and reproductive success of individuals with favorable inherited characteristics may
lead to change in the characteristics of a population.
11. The Galapagos finches, pesticide resistance in bacteria, and coloration of moths all represent
examples of evolution and survival of the fittest.
Additional notes
Complete the following.
47. Outline several lines of evidence for evolution from the fossil record.
48. Give an example of how artificial selection has been used in today’s agricultural industry.
Biology 2 /SL Review Book Topic 5.4: Evolution
Name ________________________
49. Explain a homologous structure as it would occur in whales and humans.
50. What contributions does sexual reproduction provide to the concept of natural selection and
survival of the fittest?
51. What causes competition in the explanation for natural selection?
52. According to evolution by natural selection, what will happen to individuals with characteristics that
are poorly adapted to their environment?
53. How are the characteristics of well-adapted organisms passed on to future organisms?
54. Explain how antibiotic resistance has developed in bacteria.
55. What is the major source of genetic change within bacteria that have developed antibiotic
resistance?