Name: _________________ Period: ______ Date: ______________________
Biology 11
Darwin’s Theory of Evolution
1) What did Darwin’s travels reveal to him about the number and variety of
living species?
Darwin discovered that our planet houses a variety of living things. He was
amazed by the sheer volume of species.
2) What is evolution? Why is it referred to as a theory?
Evolution is the process by which modern organisms have descended from
ancient organisms. It is the process of change is a species over time.
A theory is a hypothesis that has been rigorously tested by many
researchers and supported by strong evidence. Evolution is a theory that has
been repeatedly tested, supported by overwhelming evidence, and can be
used to explain natural phenomenon very well.
3) What does “fitness” refer to?
Fitness refers to the physical traits and behaviors that enable organisms to
survive and reproduce in their surrounding environment.
4) How is adaptation related to fitness? Provide an example to illustrate your
answer.
Adaptation is the process that enables organisms to become better suited
to their environment. Those that are well adapted to their environment are
said to be very fit. For instance, the long neck of a giraffe is an adaptation
that enables it to feed on leaves that are too high in trees, for other
grazers to reach. This increases the giraffe’s chances of survival and
reproduction.
5) What is the principal of common decent?
It is the idea that species have descended from common ancestors.
6) What is a fossil? How are fossils formed? In what type of rock do fossils
generally form in?
Fossils are preserved remains of ancient organisms (plants and animals from
the past.) Fossils are formed when organisms die and are buried in
sedimentary rock. A process of gradual replacement may result in the
formation of fossils. During gradual replacement minerals which have been
dissolved in water soak into the remains of the organism. Gradually the
minerals replace the remains, changing them to rock. The minerals harden
and form an exact copy of the organism. Fossil generally form in
sedimentary rock.
7) What is the geological time scale? What principal is the Geological time scale
based on?
The geological time scale is the record of the history of life determined by
the position of layers of rock. The geological time scale is based off the
fossil record. Fossils that are found in the lower layers are considered to
be older than those found in the upper layers.
8) Why does the fossil record not tell us the whole story regarding the
evolution of organisms?
The fossil record does not tell us the whole story regarding the evolution of
organisms because the formation of fossils can be a chancy process. Not all
organisms are fossilized, especially those that are soft bodied. Furthermore
sedimentary rock is only present in certain bodies of water, thus organisms
from the mountains and deserts may never be fossilized.
“For every organism that leaves a proper fossil, many die and vanish without
leaving a trace.”
9) What is radioactive dating? Define what a half-life is.
Radioactive dating is a technique used to determine the actual age of a fossil
on the basis of the amount of radioactive isotopes it contains.
A half-life is the amount of time it takes for half of the isotope to decay.
10) What two ideas from geology were important to Darwin’s thinking?
James Hutton - Evidence supporting the idea that the earth is very old.
Hutton proposed that rocks, mountains, and valleys had been changed
gradually by rain, heat cold and the activity of volcanoes. Because these
processes occur slowly he argued that the earth was much older than a
thousand years.
Charles Lyell - Book: Principles of Geology. Charles Lyell provided evidence
that geographical features can be built up or torn down. He provided
evidence that the land is moving and shifting. His findings led Darwin to
consider that if the Earth changes overtime, then possibly living things did
as well.
11) According to Lamarck, how did organisms acquire traits? What were his
three incorrect assumptions? Explain each assumption.
According to Lamarck organisms acquired traits based on their need to
better themselves and become more fit to their environment. The three
assumptions that Lamarck made are as follows:
1.
Desire to change: Organisms have an inborn desire to better themselves
and become fit for their environment. Example: Ancestors of birds had
a desire to fly. The effort to fly resulted in the evolution of wings
2. Use and Disuse: Change occurred because organisms could alter the shape
of their body by using it in new ways. Example: Organs increase and
decrease in size and change shape in response to an organisms needs
3. Passing on acquired traits: Characteristics acquired over an organisms
life time are passed onto their offspring Example: Weight-lifters having
muscle-bound babies
12) According to Maltus, what factors limited population growth?
According to Malthus food and living spaces are the factors that limit
population growth.
13) What is natural selection? According to Darwin what are the four factors
of natural selection?
Natural Selection means that organisms with the traits best suited to their
environment are more likely to survive and reproduce. The four factors of
natural selection are as follows.
1. Variations are found among individuals of the same species.
2. Variation are passed onto offspring (heredity)
3. Some variations allow members of a population to survive and reproduce
better than others
4. More offspring are produced than survive. Those that survive have
favorable traits.
14) Explain how the Pepper Moth incident during the Industrial Revolution is a
prime example of natural selection in action.
In the beginning of the 19th Century most of the tree trunks in England were
light brown speckled with green. Most peppered moths were mottled light
brown too. However there were always a few dark-colored moths around.
The light colored moths were better suited to their environment for they
could easily hide from predators (birds) by camouflaging themselves against
the light colored trees. However when the industrial revolution came, the
increase in pollution resulted in the trees becoming covered in black soot.
The light colored moths were no longer well suited/adapted to their
surrounding environment and as a result they were easily spotted by
predators. However the black moths were better adapted to their
surrounding environment and therefore were able to survive and reproduce.
Since the black moths were more fit, they increased in frequency.