Download Biology TOPIC 15 – Evolution and the evidence for

Solutions to Review Questions
1. There are many examples of organisms that have analogous features. Birds, bats and butterflies all have
wings but none of them share a recent common ancestor. The eye structure of octopi is similar to those of
humans.
2. This is an error. Organisms that are subjected to similar selection pressures may develop similar
characteristics but be unrelated to each other. These continents have been separated for over 200 million
years.
3. Both types of organisms live underground so therefore share similar traits. Their ancestors were
subjected to similar selection pressures.
4. Organisms can develop several different traits that enable them to survive; other organisms evolve to
either take advantage of these adaptations or to counteract them. This means that a variety of changes
will occur in all populations involved in a symbiotic relationship. Each of these changes is likely to be
subjected to selection pressures resulting in divergent evolution.
5. This is considered to be an example of coevolution as the plant has adapted to be pollinated by bats and
the bats would have adapted in such a way that they would be able to pollinate the plant.
6. Punctuated equilibrium would occur in environments where there is little or no change for a long periods
of time and then relatively short periods of time where rapid change occurs e.g. deserts. Gradualism
would occur in environments which are constantly changing at a slow rate.
7. Organism X would not be useful as an index fossil because there are insufficient of them.
8. Lava is very hot and it burns organic material.
9. Transitional fossils are useful as they have some traits that are similar to those of their ancestors and
others that are similar to those of their descendants. This enables a study of the evolution of a specific
species.
10. It is very common for items to be washed into caves and then be covered by sediments. The conditions
that are appropriate for fossilisation include rapid coverage, lack of oxygen and lack of interference by
weather or scavengers. Caves provide all of these conditions.
11. Organisms from this time period were small and soft bodied so there were no hard components to be
preserved. At best a thin film or smear would be preserved.
12. Stratigraphy would be an appropriate relative dating technique and radio carbon dating would be an
appropriate absolute dating technique.
13. Six half-lives have passed so the amount of time that is passed is 700 million times 6 = 4200 million.
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14. The answers are as follows:
i. Layer 6 is the youngest
ii. Layers 1 and 7; Layers 3 and 8; Layers 4 and 9; Layers 5 and 10.
15. Large canine teeth, large thick bones and deep grooves in the bones indicating large muscles.
16. Species A and B are the most closely related. The temperature required to separate the hybrid strand is
the highest indicating the attraction between these strands is the greatest, meaning that these two species
are the most closely related.
17. E, F, C, D.
18. If evolution is plausible then you would expect to find organisms that are closely related to each other in
similar locations unless there are reasons for them not to be, such as species that are highly mobile or an
explainable phenomenon such as continental drift or being moved by humans. The biogeographic
distribution generally follows the expected pattern.
19. The hoary fox.
20. The diagram should look like this.
Shark
Goldfish
House cat
Dolphin
Chimpanzee
Human
21. No. Organisms can develop analogous features as a result of being subjected to similar selection
pressures.
22. Divergent evolution. Each of the structures mentioned is actually a modification of the same basic
structure which means that these structures are homologous. Analogous features appear similar but are
actually structurally different.
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23. Natural selection occurs as a result of the impact of a selection pressure on the phenotype of the
individual. If the structure or organ no longer has a purpose then there will be no selection pressure on
the structure and the result is the structure atrophies over a period of time rather than adapting to
changing conditions.
24. This information indicates that the original ancestor of the whale was an organism with legs that walked
on land.
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