Download 6.1 Evidence of evolution – Questions and answers Q1. Bk Ch6 S6.1

6.1 Evidence of evolution – Questions and answers
Q1.
Bk Ch6 S6.1 Q1
Outline, using a named example, how changes in the physical or chemical conditions in the
environment can lead to changes in a species.
A1.
Bk Ch6 S6.1 A1
Example (peppered moth):
The peppered moth represents an example of how physical change in the environment has led to a
change in a population. In unpolluted forests light-coloured moths have the advantage because they are
camouflaged against the light-coloured bark of the trees. Any dark-coloured moths in the population
would be easy prey for birds. However, in polluted forests close to cities the bark of trees is darker in
colour and the dark-coloured moths have the advantage of camouflage, so the light-coloured moths are
more likely to be eaten. This change in the physical environment has led to an increase in the number
of dark-coloured moths and a decrease in the number of light-coloured moths in the populations that
inhabit these forests.
Q2.
Bk Ch6 S6.1 Q2
Explain how transitional forms of organisms in the fossil record support the theory of evolution.
Outline two animal examples and one plant example.
A2.
Bk Ch6 S6.1 A2
Transitional or intermediate forms of organisms have structural similarities with organisms that
preceded them on Earth as well as with more recent forms. This suggests that one group of organisms
evolved from another or from a common ancestor. For example, Archaeopteryx was a flying dinosaur
that lived during the Jurassic Period. The presence of feathers on Archaeopteryx along with other
characteristics shared by birds and reptiles leads scientists to believe that modern birds evolved from
the reptiles. Crossopterygian fish that lived about 400 million years ago are another example. These
fish could obtain oxygen from the air and had bones in their fins, suggesting that they were mobile on
the land. The existence of this transitional form supports the theory that amphibians evolved from fish
through this line. The now-extinct seed ferns are an example of a transitional form of plants. Although
their general structure resembled modern ferns they produced seeds attached to leaves and along with
other features are now thought to be more closely related to gymnosperms.
Q3.
Bk Ch6 S6.1 Q3
a
b
c
Explain what is meant by biogeography.
Outline how the biogeography of the waratah lends support to the theory of evolution suggested
by Alfred Wallace.
Is the evolution of the waratah an example of divergent or convergent evolution? Explain your
answer.
A3.
Bk Ch6 S6.1 A3
a
b
c
Biogeography is the study of the distribution of living organisms.
According to Alfred Wallace the plants and animals of Asia evolved along separate lines from
those of Australia and New Guinea. His theory is supported by the biogeography of the waratah.
The three different genera of the waratah are distributed in New Guinea and along the eastern
coast of Australia as well as in forests in South America, but none occur in Asia.
Divergent evolution. The presence of a number of closely related genera on landmasses in close
proximity to one another suggests that at some time in history the landmasses were connected and
that the different genera represented today evolved from a common ancestor.
6.1 Evidence for evolution QA
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Q4.
Bk Ch6 S6.1 Q4
Use Figure 6.10 to explain how the embryology of organisms provides important information in our
understanding of evolution.
A4.
Bk Ch6 S6.1 A4
Similarities in the embryology of different organisms can provide important information about the
relationships between the organisms. For example, in the diagram shown, the presence of aortic arches
in sharks, amphibians and humans is quite different in the adult form of each kind of organism.
However, they all show a basic pattern of six pairs of aortic arches in the embryonic stage. Different
numbers of these paired arches are lost during development in each of the different kinds of organisms.
This and other similarities in embryology suggest that these organisms are related by a common
ancestry.
Q5.
Bk Ch6 S6.1 Q5
Study the forelimbs of the vertebrates shown in Figure 6.11. Explain what your observations suggest
about the relationship between the different organisms.
A5.
Bk Ch6 S6.1 A5
The forelimbs of each of the animals shown have five digits in each limb. This comparative anatomy
suggests that the organisms are related to one another and probably shared a common ancestor.
Q6.
Bk Ch6 S6.1 Q6
a
b
Explain how biochemistry is used to analyse evolutionary relationships.
Outline how biochemical studies suggest a relationship between humans and other mammals.
A6.
Bk Ch6 S6.1 A6
a
b
Biochemistry can be used to analyse evolutionary relationships by comparing the degree of
molecular similarity. The greater the degree of similarity of certain molecules between species the
closer the evolutionary relationship.
Analysis of amino acid sequences between humans and other primates reveals a greater degree of
similarity between humans and chimpanzees than between humans and gorillas, gibbons,
monkeys and other mammals. This suggests that humans are more closely related to chimpanzees
than to these other organisms.
Q7.
Bk Ch6 S6.1 Q7
Explain the difference between evolutionary convergence and evolutionary divergence. Use examples
to illustrate your answer.
A7.
Bk Ch6 S6.1 A7
Convergent evolution is the term used to account for the presence of similar adaptations to similar
environmental pressures in unrelated species. For example, the flippers of dolphins and seals are
similar in appearance and function but these organisms are not closely related. The presence of similar
modified limbs is an adaptation to a similar environment. Divergent evolution begins with a single
ancestral species that has been geographically dispersed and the different populations have been subject
to different environmental pressures, resulting in the evolution of different but related species.
Darwin’s finches are an example. Different species of finch inhabit the different islands of the
Galapagos archipelago. The different environmental pressures on the different islands account for the
differences between these closely related species.
6.1 Evidence for evolution QA
Copyright
© Pearson Australia (a division of Pearson Australia Group Pty Ltd)
page 2 of 2