A. How are mutations, adaptation and evolution related?
Support your answer with examples.
Mutation is a change in the genetic sequence (DNA) of an
organism. If a mutation is advantageous it will help the
organism to survive long enough to reproduce. The mutation
then may be passed on to the organisms’ offspring, spreading
the advantageous mutation. When the mutation spreads
throughout a population, the organisms within the population
will be better adapted to their environment. Over time, the
entire species evolves and the advantageous mutation is a
normal part of the species.
Examples:
Giraffes Neck
Opposable Thumbs
B. Compare and Contrast Darwin and Lamarck’s theories on
evolution and adaptation. Support your answer with
examples.
Charles Darwin developed the theory of evolution. His claim
was that all organisms shared a common ancestor and
evolved over time through the process of natural selection.
Darwin believed that these changes happened gradually as a
result of mutations and adaptation. For example, Darwin
believed that there was a mutation that made a giraffe with
a longer neck. That giraffe could eat plants that other giraffes
could not; therefore it survived longer and was able to pass
on those traits to its offspring. Over time mutations
continued and over a long period of time, giraffes gradually
had longer necks. Lamarck believed that organisms evolved
due to use of a specific part of the organism. For example,
according to Lamarck, if a giraffe stretched its neck enough
trying to gather food it would eventually stretch and become
longer.
C. Explain the four steps of natural selection. Determine which
step is the most essential step and support your decision
with evidence.
Natural selection occurs in four steps: overproduction,
genetic variation, struggle to survive and successful
reproduction. Overproduction ensures that each species
makes more offspring than can survive to maturity. Genetic
variation amongst those offspring allows for some members
of the species to have traits that are better suited for survival
than others. The organisms then must struggle to survive
because there are not enough resources for every organism
to reach maturity. The organisms with the better traits will
then survive to successfully reproduce. Successful
reproduction is the most important step in natural section
because if an organism is able to survive to reproduce, it has
traits that are best suited for its environment. It will then
pass those traits to its offspring and keep the species alive.
D. Choose two pieces of evidence that support evolution.
Explain how each piece of evidence helps to validate the
theory.
The fossil record gives scientist an approximate order in which
organisms evolved. It also tells us about organisms that are
extinct.
Radiometric dating helps to show the exact age of fossils. This
also shows how organisms evolved overtime.
Anatomical similarities show that many of the body structures
of animals are very similar. This helps to support that they had
a common ancestor. For example, human arms, cats front legs
and whale fins all have similar bone structure.
Genetic similarities show that the DNA of many organisms are
closely matched. Humans and monkeys share 96% of the same
DNA.
Embryology shows that developing offspring are very similar
between many species. This shows common ancestry. For
example mice and human embryos look very similar.
Vestigial structures are structures that are present in organisms
that are no longer needed for survival. They show that there is
a common ancestry among species. For examples, whales have
hip and leg bones.